Search results for: micro fabrication

Authors: Hadjer Chellia

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the present study reports on second language use among Algerian international students in the UK. In Algeria, French has an important status among the Algerian verbal repertoires due to colonial reasons. This has triggered many language conflicts and many debates among policy makers in Algeria. In higher education, Algerian English students’ sociolinguistic profile is characterised by the use of French as a sign of prestige. What may leave room for debate is the effect of crossing borders towards the UK as a result of international mobility programmes, a transition which could add more complexity since French, is not so significant as a language in the UK context. In this respect, the micro-objective is to explore the fate of French use among Ph.D. students in the UK as a newly established group vis-à-vis English. To fulfill the purpose of the present inquiry, the research employs multiple approaches in which semi-structured interview is a primary source of data to know participants’ attitudes about French use, targeting both their pre-migratory experience and current one. Web-based questionnaires are set up to access larger population. Focus group sessions are further procedures of scrutiny in this piece of work to explore the actual linguistic behaviours. Preliminary findings from both interviews and questionnaires reveal that students’ current experience, particularly living in the UK, affects their pre-migratory attitudes towards French language and its use. The overall findings are expected to bring manifold contributions to the field of research among which is setting factors that influence language use among newly established émigrés communities. The research is also relevant to international students’ experience of study abroad in terms of language use in the guise of internationalization of higher education, mobility and exchange programmes. It could contribute to the sociolinguistics of the Algerian diaspora: the dispersed residence of non-native communities - not to mention its significance on the Algerian research field abroad.

Keywords: Algerian diaspora, French language, language maintenance, language shift, mobility

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Authors: Ka Ho Yau, Jan Frederick Engels, Kwok Kei Lai, Reinhard Renneberg

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Lateral flow test is a prevalent technology in various sectors such as food, pharmacology and biomedical sciences. Colloidal gold (CG) is widely used as the signalling molecule because of the ease of synthesis, bimolecular conjugation and its red colour due to intrinsic SPRE. However, the production of colloidal gold is costly and requires vigorous conditions. The stability of colloidal gold are easily affected by environmental factors such as pH, high salt content etc. Silica nanoparticles are well known for its ease of production and stability over a wide range of solvents. Using reverse micro-emulsion (w/o), silica nanoparticles with different sizes can be produced precisely by controlling the amount of water. By incorporating different water-soluble dyes, a rainbow colour of the silica nanoparticles could be produced. Conjugation with biomolecules such as antibodies can be achieved after surface modification of the silica nanoparticles with organosilane. The optimum amount of the antibodies to be labelled was determined by Bradford Assay. In this work, we have demonstrated the ability of the dye-doped silica nanoparticles as a signalling molecule in lateral flow test, which showed a semi-quantitative measurement of the analyte. The image was further analysed for the LOD=10 ng of the analyte. The working range and the linear range of the test were from 0 to 2.15μg/mL and from 0 to 1.07 μg/mL (R2=0.988) respectively. The performance of the tests was comparable to those using colloidal gold with the advantages of lower cost, enhanced stability and having a wide spectrum of colours. The positives lines can be imaged by naked eye or by using a mobile phone camera for a better quantification. Further research has been carried out in multicolour detection of different biomarkers simultaneously. The preliminary results were promising as there was little cross-reactivity being observed for an optimized system. This approach provides a platform for multicolour detection for a set of biomarkers that enhances the accuracy of diseases diagnostics.

Keywords: colorimetric detection, immunosensor, paper-based biosensor, silica

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Authors: Xiao-Mei Zhang, Sian-Hong Tseng, Ming-Yen Lu

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Two-dimensional (2D) transition metal dichalcogenides (TMDCs), such as MoS₂, have attracted considerable attention owing to the unique optical and electronic properties related to its 2D ultrathin atomic layer structure. MoS₂ is becoming prevalent in post-silicon digital electronics and in highly efficient optoelectronics due to its extremely low thickness and its tunable band gap (Eg = 1-2 eV). For low-power, high-performance complementary logic applications, both p- and n-type MoS₂ FETs (NFETs and PFETs) must be developed. NFETs with an electron accumulation channel can be obtained using unintentionally doped n-type MoS₂. However, the fabrication of MoS₂ FETs with complementary p-type characteristics is challenging due to the significant difficulty of injecting holes into its inversion channel. Plasma treatments with different species (including CF₄, SF₆, O₂, and CHF₃) have also been found to achieve the desired property modifications of MoS₂. In this work, we demonstrated a p-type multilayer MoS₂ enabled by selective-area doping using CHF₃ plasma treatment. Compared with single layer MoS₂, multilayer MoS₂ can carry a higher drive current due to its lower bandgap and multiple conduction channels. Moreover, it has three times the density of states at its minimum conduction band. Large-area growth of MoS₂ films on 300 nm thick SiO₂/Si substrate is carried out by thermal decomposition of ammonium tetrathiomolybdate, (NH₄)₂MoS₄, in a tube furnace. A two-step annealing process is conducted to synthesize MoS₂ films. For the first step, the temperature is set to 280 °C for 30 min in an N₂ rich environment at 1.8 Torr. This is done to transform (NH₄)₂MoS₄ into MoS₃. To further reduce MoS₃ into MoS₂, the second step of annealing is performed. For the second step, the temperature is set to 750 °C for 30 min in a reducing atmosphere consisting of 90% Ar and 10% H₂ at 1.8 Torr. The grown MoS₂ films are subjected to out-of-plane doping by CHF₃ plasma treatment using a Dry-etching system (ULVAC original NLD-570). The radiofrequency power of this dry-etching system is set to 100 W and the pressure is set to 7.5 mTorr. The final thickness of the treated samples is obtained by etching for 30 s. Back-gated MoS₂ PFETs were presented with an on/off current ratio in the order of 10³ and a field-effect mobility of 65.2 cm²V⁻¹s⁻¹. The MoS₂ PFETs photodetector exhibited ultraviolet (UV) photodetection capability with a rapid response time of 37 ms and exhibited modulation of the generated photocurrent by back-gate voltage. This work suggests the potential application of the mild plasma-doped p-type multilayer MoS₂ in UV photodetectors for environmental monitoring, human health monitoring, and biological analysis.

Keywords: photodetection, p-type doping, multilayers, MoS₂

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Authors: Yatimah Alias, Tilagam Marimuthu, M. R. Mahmoudian, Sharifah Mohamad

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The rapid growth of science and technology in energy and environmental fields has enlightened the substantial importance of the conducting polymer and metal composite materials engineered at nano-scale. In this study, polypyrrole-cobalt composites (PPy-Co Cs) and polypyrrole-nickel oxide composites (PPy-NiO Cs) were prepared by a simple and facile chemical polymerization method with an aqueous solution of pyrrole monomer in the presence of metal salt. These composites then fabricated into non-enzymatic hydrogen peroxide (H2O2) and glucose sensor. The morphology and composition of the composites are characterized by the Field Emission Scanning Electron Microscope, Fourier Transform Infrared Spectrum and X-ray Powder Diffraction. The obtained results were compared with the pure PPy and metal oxide particles. The structural and morphology properties of synthesized composites are different from those of pure PPy and metal oxide particles, which were attributed to the strong interaction between the PPy and the metal particles. Besides, a favorable micro-environment for the electrochemical oxidation of H2O2 and glucose was achieved on the modified glassy carbon electrode (GCE) coated with PPy-Co Cs and PPy-NiO Cs respectively, resulting in an enhanced amperometric response. Both PPy-Co/GCE and PPy-NiO/GCE give high response towards target analyte at optimum condition of 500 μl pyrrole monomer content. Furthermore, the presence of pyrrole monomer greatly increases the sensitivity of the respective modified electrode. The PPy-Co/GCE could detect H2O2 in a linear range of 20 μM to 80 mM with two linear segments (low and high concentration of H2O2) and the detection limit for both ranges is 2.05 μM and 19.64 μM, respectively. Besides, PPy-NiO/GCE exhibited good electrocatalytic behavior towards glucose oxidation in alkaline medium and could detect glucose in linear ranges of 0.01 mM to 0.50 mM and 1 mM to 20 mM with detection limit of 0.33 and 5.77 μM, respectively. The ease of modifying and the long-term stability of this sensor have made it superior to enzymatic sensors, which must kept in a critical environment.

Keywords: metal oxide, composite, non-enzymatic sensor, polypyrrole

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Authors: Sani Ismaila, Shafiu Yau, Abubakar Salisu, Buhari Salisu, Sharifat Balogun, Mustapha Abubakar, Biobaku Khalid, Agaie Bello

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Over the years, Japanese quail egg has been in use in the management of diseases. The objective of this study was to evaluate the analgesic, anti-inflammatory and gastroprotective effects of raw Quail egg (yolk + albumin) in rats. Pain was assessed in rats by recording the latent period and writing reflex, anti-inflammatory effect was determined using both motility and compression test, while the gastro-protective effects were assessed by observing the histology of the stomach after diclofenac-induced gastric ulcers and subsequent treatment with the quail egg, Rats were randomly assigned into 4 groups; Groups I: were the control non-treated (NT), Group II were treated with Tramadol 50 mg/kg/Os (TMD) or Indomethacin (IND) 5mg/kg/Os (positive control for the writhing reflex determination), while group III and IV were treated with 3 and 6g/kg of raw quail egg respectively). Groups treated with quail egg in both doses showed a significant increase in the latent period (p <0 .05) when compared to the control NT, but lower than the group treated with tramadol at 20mins interval (p<0.05). Writing reflexes decrease in groups II, III, and IV compared to the NT group (p < 0.05). While motility increases significantly (p < 0.05) in groups II, compared to I (p<0.05). Control non-treated rats showed a quicker and extensive response to compression using the Vanier calliper on the inflamed paw compared to groups II-IV (p < 0.05). Histological studies of the stomach revealed sloughing of the epithelia, cellular infiltration with micro abscesses in the non-treated, while groups treated concurrently with quail egg showed proliferation of the glandular epithelia and goblet cells, and those treated 30 minutes before diclofenac administration showed proliferation of glands and thickening of the squamous epithelia. This study showed that quail egg has analgesic, anti-inflammatory and gastro-protective potentials and can be used as adjuvant treatment whenever COX-2 enzymes inhibitors are indicated.

Keywords: analgesia, anti-inflammatory, gastroprotective effect, japanese quail egg

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Authors: Wisdom Robert Duruji, Oluwasegun Christopher Akinleye

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This study reports on the impact of different ripening accelerators on the microbial load and proximate composition of plantain (Musa paradisiaca) and Banana (Musa sapientum) during the ripening process, and the nutrition implication for food security. The study comprised of four treatments, namely: Calcium carbide, Irvingia gabonensis fruits, Newbouldia laevis leaves and a control, where no ripening accelerator was applied to the fingers of plantain and banana. The unripe and ripened plantain and banana were subjected to microbial analysis by isolating and enumerating their micro flora using pour plate method; and also, their proximate composition was determined using standard methods. The result indicated that the bacteria count of plantain increased from 3.25 ± 0.33 for unripe to 5.31 ± 0.30 log cfu/g for (treated) ripened, and that of banana increased from 3.69 ± 0.11 for unripe to 5.26 ± 0.21 log cfu/g for ripened. Also, the fungal count of plantain increased from 3.20 ± 0.16 for unripe to 4.88 ± 0.22 log sfu/g for ripened; and that of banana increased from 3.61 ± 0.19 for unripe to 5.43 ± 0.26 for ripened. Ripened plantain fingers without any ripening accelerator (control) had significantly (p < 0.05) higher values of crude protein 3.56 ± 0.06%, crude fat 0.42 ± 0.04%, total ash 2.74 ± 0.15 and carbohydrate 31.10 ± 0.20; but with significantly lower value of moisture 62.14 ± 0.07% when compared with treated plantain. The proximate composition trend of treated and banana fingers control is similar to that of treated and plantain control, except that higher moisture content of 75.11 ± 0.07% and lesser protein, crude fat, total ash and carbohydrate were obtained from treated and ripened banana control when the treatments were compared with that of plantain. The study concluded that plantain is more nutritious (mealy) than a banana; also, the ripening accelerators increased the microbial load and reduced the nutritional status of plantain and banana.

Keywords: food nutrition, calcium carbide, rvingia gabonensis, newbouldia laevis, plantain, banana

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Authors: K. R. Sreenivas, Shaurya Kaushal

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After sunset, under calm & clear-sky nocturnal conditions, the air layer near the surface containing aerosols cools through radiative processes to the upper atmosphere. Due to this cooling, surface air-layer temperature can fall 2-6 degrees C lower than the ground-surface temperature. This unstable convection layer, on the top, is capped by a stable inversion-boundary layer. Radiative divergence, along with the convection within the surface layer, governs the vertical transport of heat and moisture. Micro-physics in this layer have implications for the occurrence and growth of the fog layer. This particular configuration, featuring a convective mixed layer beneath a stably stratified inversion layer, exemplifies a classic case of penetrative convection. In this study, we conduct numerical simulations of the penetrative convection phenomenon within the nocturnal atmospheric surface layer and elucidate its relevance to the dynamics of fog layers. We employ field and laboratory measurements of aerosol number density to model the strength of the radiative cooling. Our analysis encompasses horizontally averaged, vertical profiles of temperature, density, and heat flux. The energetic incursion of the air from the mixed layer into the stable inversion layer across the interface results in entrainment and the growth of the mixed layer, modeling of which is the key focus of our investigation. In our research, we ascertain the appropriate length scale to employ in the Richardson number correlation, which allows us to estimate the entrainment rate and model the growth of the mixed layer. Our analysis of the mixed layer and the entrainment zone reveals a close alignment with previously reported laboratory experiments on penetrative convection. Additionally, we demonstrate how aerosol number density influences the growth or decay of the mixed layer. Furthermore, our study suggests that the presence of fog near the ground surface can induce extensive vertical mixing, a phenomenon observed in field experiments.

Keywords: inversion layer, penetrative convection, radiative cooling, fog occurrence

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Authors: Husam Mohammed Saleh Alziyadi

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The drilling fluid has a significant impact on drilling efficiency. Drilling fluids have several functions which make them most important within the drilling process, such as lubricating and cooling the drill bit, removing cuttings from down of hole, preventing formation damage, suspending drill bit cuttings, , and also removing permeable formation as a result, the flow of fluid into the formation process is delayed. In the oil and gas sector, unconventional shale reserves have been a central player in meeting world energy demands. Oil-based drilling fluids (OBM) are generally favored for drilling shale plays due to negligible chemical interactions. Nevertheless, the industry has been inspired by strict environmental regulations to design water-based drilling fluids (WBM) capable of regulating shale-water interactions to boost their efficiency. However, traditional additives are too large to plug the micro-fractures and nanopores of the shale. Recently, nanotechnology in the oil and gas industries has shown a lot of promise, especially with drilling fluids based on nanoparticles. Nanotechnology has already made a huge contribution to technical developments in the energy sector. In the drilling industry, nanotechnology can make revolutionary changes. Nanotechnology creates nanomaterials with many attractive properties that can play an important role in improving the consistency of mud cake, reducing friction, preventing differential pipe sticking, preserving the stability of the borehole, protecting reservoirs, and improving the recovery of oil and gas. The selection of suitable nanomaterials should be based on the shale formation characteristics intended for drilling. The size, concentration, and stability of the NPs are three more important considerations. The effects of the environment are highly sensitive to these materials, such as changes in ionic strength, temperature, or pH, all of which occur under downhole conditions. This review paper focused on the previous research and recent development of environmentally friendly drilling fluids according to the regulatory environment and cost challenges.

Keywords: nanotechnology, WBM, Drilling Fluid, nanofluids

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Authors: Indujeeva Keerthila Peiris

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The secular view of mindfulness has some connotation to the original meaning of mindfulness mentioned in the Theravada Buddhist texts (Pāli Canon), but there is a substantial difference in the meaning of the two. Secular Mindfulness Based Interventions (MBI) focus on stilling the mind, which may provide short-term benefits and help individuals to deal with physical pain, grief, and distress. However, as with many popular educational innovations, the foundational values of mindfulness strategies have been distorted and subverted in a number of instances in which ‘McMindfulness’ programmes have been implemented with a view to reducing mindfulness mediation as a self-help technique that is easily misappropriated for the exclusive pursuit of corporate objectives, employee pacification, and commercial profit. The intention of this paper is not to critique the misappropriations of mindfulness. Instead, to go back to the root source and bring insights from the Buddhist Pāli Canon and its associated teachings on mindfulness in its own terms. In the Buddha’s discourses, as preserved in the Pāli Canon, there is nothing more significant than the understanding and practice of ‘Satipatthãna’. The Satipatthāna Sutta , the ‘Discourse on the Establishment of Mindfulness,’ opens with a proclamation highlighting both the purpose of this training and its methodology. The right practice of mindfulness is the gateway to understanding the Buddha’s teaching. However, although this concept is widely discussed among the Dhamma practitioners, it is the least understood one of them all. The purpose of this paper is to understand deeper meaning of mindfulness as it was originally intended by the Teacher. The natural state of mind is that it wanders. It wanders into the past, the present, and the future. One’s ability to hold attention to a mind object (emotion, thought, feeling, sensation, sense impression) called ‘concentration’. The intentional concentration process does not lead to wisdom. However, the development of wisdom starts when the mind is calm, concentrated, and unified. The practice of insight contemplation aims at gaining a direct understanding of the real nature of phenomena. According to the Buddha’s teaching, there are three basic facts of all existence: 1) impermanence (anicca in Pāli) ; 2) fabrication (also commonly known as suffering, unsatisfactoriness, sankhara or dukka in Pāli); 3) not-self (insubstantiality or impersonality, annatta in Pāli ). The entire Buddhist doctrine is based on these three facts. The problem is our ignorance covers reality. It is not that a person sees the emptiness of them or that we try to see the emptiness of our experience by conceptually thinking that they are empty. It is an experiential outcome that happens when the cause-and- effect overrides the self-view (sakkaya dhitti), and ignorance is known as ignorance and eradicated once and for all. Therefore, the right view (samma dhitti) is the starting point of the path, not ethical conduct (sila) or samadhi (jhana). In order to develop the right view, we need to first listen to the correct Dhamma and possess Yoniso manasikara (right comprehension) to know the five aggregates as five aggregates.

Keywords: mindfulness, spirituality, buddhism, pali canon

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Authors: Asmaa Hamdy, Israa Nassar, Tarek Aly

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Introduction: Femoral fractures are the most common presentation in the Emergency Department (ED), and they can present as isolated injuries or as part of a polytrauma situation. To provide optimum pain management care to these patients, practitioners must be well prepared and current with utilizing modern evidence-based knowledge and practices. Management of pain associated with fracture femur in the emergency department has a critical role in the satisfaction of patients and preventing further complications. This study aimed to evaluate the analgesic efficacy of ultrasound-guided femoral nerve block compared with intravenous fentanyl in fractures of the femur in patients presented to the Emergency Department. Patients and Methods: Fifty patients with femur fractures were divided into two groups: Group A: In this group (twenty-five patients) were given intravenous fentanyl 2 micro-grams/kg and re-assessed for pain by Visual Analogue Score (VAS). Group B: In this group (twenty-five patients) underwent ultrasonography-guided femoral nerve block and were re-assessed for pain by VAS. Results: VAS score on the movement of the fractured limb between group A and group B at a 10-minute post-intervention period shows P= 0.043, and hence the difference is significant. VAS score on the movement of the fractured limb between group A and group B during a 10-minute post-intervention period showed a significant difference. Seventeen patients in group A had major PID with a percentage of 63% VS 10 patients in group B with a percentage of 37%. conclusion: both femoral nerve block and intravenous fentanyl are effective in relieving pain in patients with femur fractures. But femoral nerve block provides better and more intense analgesia and major pain intensity difference in less time. Moreover, the use of FNB had fewer side effects and more Hemodynamics stability compared to opioids.

Keywords: femur fracture, nerve block, fentanyl, ultrasound guided

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Authors: Sellidj Abdelaziz, Lebaili Soltane

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A cobalt-based alloy type Co-Cr-Ni-WC was deposited by plasma transferred arc projection (PTA) on a stainless steel valve. The alloy is characterized at the equilibrium by a solid solution Co (γ) mainly dendritic, and eutectic carbides M₇C₃ and ηM₆C. At the deposit/substrate interface, this microstructure is modified by the fast cooling mode of the alloy when applied in the liquid state on the relatively cold steel substrate. The structure formed in this case is heterogeneous and metastable phases can occur and evolve over temperature service. Coating properties and reliability are directly related to microstructures formed during deposition. We were interested more particularly in this microstructure formed during the solidification of the deposit in the region of the interface joining the soldered couple and its evolution during cyclic heat treatments at temperatures similar to those of the thermal environment of the valve. The characterization was carried out by SEM-EDS microprobe CAMECA, XRD, and micro hardness profiles. The deposit obtained has a linear and regular appearance that is free of cracks and with little porosity. The morphology of the microstructure represents solidification stages that are relatively fast with a temperature gradient high at the beginning of the interface by forming a plane front solid solution Co (γ). It gradually changes with the decreasing temperature gradient by getting farther from the junction towards the outer limit of the deposit. The matrix takes the forms: cellular, mixed (cells and dendrites) and dendritic. Dendritic growth is done according to primary ramifications in the direction of the heat removal which takes place in the direction perpendicular to the interface, towards the external surface of the deposit, following secondary and tertiary undeveloped arms. The eutectic carbides M₇C₃ and ηM₆C formed are very thin and are located in the intercellular and interdendritic spaces of the solid solution Co (γ).

Keywords: Co-Ni-Cr-W-C alloy, solid deposit, microstructure, carbides, cyclic heat treatment

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Authors: Sanchita Baitalik, Nijhuma Kayal, Omprakash Chakrabarti

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Recently SiC ceramics have been a focus of interest in the field of porous materials due to their unique combination of properties and hence they are considered as an ideal candidate for catalyst supports, thermal insulators, high-temperature structural materials, hot gas particulate separation systems etc. in different industrial processes. Several processing methods are followed for fabrication of porous SiC at low temperatures but all these methods are associated with several disadvantages. Therefore processing of porous SiC ceramics at low temperatures is still challenging. Concerning that of incorporation of secondary bond phase additives by an infiltration technique should result in a homogenous distribution of bond phase in the final ceramics. Present work is aimed to synthesis cordierite (2MgO.2Al2O3.5SiO2) bonded porous SiC ceramics following incorporation of sol-gel bond phase precursor into powder compacts of SiC and heat treating the infiltrated body at 1400 °C. In this paper the primary aim was to study the effect of infiltration of a precursor sol of cordierite into a porous SiC powder compact prepared with pore former of different particle sizes on the porosity, pore size, microstructure and the mechanical properties of the porous SiC ceramics. Cordierite sol was prepared by mixing a solution of magnesium nitrate hexahydrate and aluminium nitrate nonahydrate in 2:4 molar ratio in ethanol another solution containing tetra-ethyl orthosilicate and ethanol in 1:3 molar ratio followed by stirring for several hours. Powders of SiC (α-SiC; d50 =22.5 μm) and 10 wt. % polymer microbead of two sizes 8 and 50µm as the pore former were mixed in a suitable liquid medium, dried and pressed in the form of bars (50×20×16 mm3) at 23 MPa pressure. The well-dried bars were heat treated at 1100° C for 4 h with a hold at 750 °C for 2 h to remove the pore former. Bars were evacuated for 2 hr upto 0.3 mm Hg pressure into a vacuum chamber and infiltrated with cordierite precursor sol. The infiltrated samples were dried and the infiltration process was repeated until the weight gain became constant. Finally the infiltrated samples were sintered at 1400 °C to prepare cordierite bonded porous SiC ceramics. Porous ceramics prepared with 8 and 50 µm sized microbead exhibited lower oxidation degrees of respectively 7.8 and 4.8 % than the sample (23 %) prepared with no microbead. Depending on the size of pore former, the porosity of the final ceramic varied in the range of 36 to 40 vol. % with a variation of flexural strength from 33.7 to 24.6 MPa. XRD analysis showed major crystalline phases of the ceramics as SiC, SiO2 and cordierite. Two forms of cordierite, α-(hexagonal) and µ-(cubic), were detected by the XRD analysis. The SiC particles were observed to be bonded both by cristobalite with fish scale morphology and cordierite with rod shape morphology and thereby formed a porous network. The material and mechanical properties of cordierite bonded porous SiC ceramics are good in agreement to carry out further studies like thermal shock, corrosion resistance etc.

Keywords: cordierite, infiltration technique, porous ceramics, sol-gel

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Authors: Olufunmilayo Folaranmi

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This research was carried out to examine the impact of socio-cultural factors on the management and utilization of solid waste in Ibadan Metropolis. A descriptive survey research design was adopted for the study while a systematic and stratified random sampling technique was used to select 300 respondents which were categorized into high, middle and low-density areas. Four hypothesis were tested using chi-square test on variables of unavailability of waste disposal facilities and waste management, negligence of contractors to liaise with community members, lack of adequate environmental education and waste management and utilization, low level of motivation of sanitation workers with solid wastes management, lack of community full participation with solid waste management and utilization. Results showed that significant effect of waste disposal facilities on solid waste management and utilization (X2 +16.6, P < .05). Also, there is a significant relationship between negligence of the contractors to liaise with community elites with improper disposal (X2 = 87.5, P < .05). The motivation of sanitation workers is significantly related to solid waste management (X2 = 70.4, P < .05). Adequate environmental education and awareness influenced solid waste management. There was also a significant relationship between lack of community participation with waste management disposal and improper waste disposal. Based on the findings from the study it was recommended that the quality of life in urban centers should be improved, social welfare of the populace enhanced and environment should be adequately attended to. Poverty alleviation programmes should be intensified and made to live beyond the life of a particular administration, micro-credit facilities should be available to community members to promote their welfare. Lastly, sustained environmental education programmes for citizens at all levels of education, formal and informal through the use of agencies like Ethical and Attitudinal Reorientation Commission (EARCOM) and the National Orientation Agency (NOA).

Keywords: management, social welfare, socio-cultural factors, solid waste

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Authors: Yu-Wen Huang, Yi-Cheng Chiang

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With urban development, lots of buildings are built around the city. The buildings always affect the urban wind environment. The accelerative situation of wind caused of buildings often makes pedestrians uncomfortable, even causes the accidents and dangers. Factors influencing pedestrian level wind including atmospheric boundary layer, wind direction, wind velocity, planting, building volume, geometric shape of the buildings and adjacent interference effects, etc. Planting has many functions including scraping and slowing urban heat island effect, creating a good visual landscape, increasing urban green area and improve pedestrian level wind. On the other hand, urban square is an important space element supporting the entrance to buildings, city landmarks, and activity collections, etc. The appropriateness of urban square environment usually dominates its success. This research focuses on the effect of tree-planting on the wind environment of urban square. This research studied the square belt of Taichung City Hall. Taichung City Hall is a cuboid building with a large mass opening. The square belt connects the front square, the central opening and the back square. There is often wind draft on the square belt. This phenomenon decreases the activities on the squares. This research applies tree-planting to improve the wind environment and evaluate the effects of two types of planting configuration. The Computational Fluid Dynamics (CFD) simulation analysis and extensive field measurements are applied to explore the improve efficiency of planting configuration on wind environment. This research compares efficiencies of different kinds of planting configuration, including the clustering array configuration and the dispersion, and evaluates the efficiencies by the SET*.

Keywords: micro-climate, wind environment, planting configuration, comfortableness, computational fluid dynamics (CFD)

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Authors: Anželika Teresė

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In order to solve issues in sign language linguistics, address matters pertaining to maintaining high quality of sign language (SL) translation, contribute to dispelling misconceptions about SL and deaf people, and raise awareness and understanding of the deaf community heritage, this presentation discusses literature in Lithuanian Sign Language (LSL) and inherent metaphors that are created by using the phonological parameter –handshape, location, movement, palm orientation and nonmanual features. The study covered in this presentation is twofold, involving both the micro-level analysis of metaphors in terms of phonological parameters as a sub-lexical feature and the macro-level analysis of the poetic context. Cognitive theories underlie research of metaphors in sign language literature in a range of SL. The study follows this practice. The presentation covers the qualitative analysis of 34 pieces of LSL literature. The analysis employs ELAN software widely used in SL research. The target is to examine how specific types of each phonological parameter are used for the creation of metaphors in LSL literature and what metaphors are created. The results of the study show that LSL literature employs a range of metaphors created by using classifier signs and by modifying the established signs. The study also reveals that LSL literature tends to create reference metaphors indicating status and power. As the study shows, LSL poets metaphorically encode status by encoding another meaning in the same sign, which results in creating double metaphors. The metaphor of identity has been determined. Notably, the poetic context has revealed that the latter metaphor can also be identified as a metaphor for life. The study goes on to note that deaf poets create metaphors related to the importance of various phenomena significance of the lyrical subject. Notably, the study has allowed detecting locations, nonmanual features and etc., never mentioned in previous SL research as used for the creation of metaphors.

Keywords: Lithuanian sign language, sign language literature, sign language metaphor, metaphor at the phonological level, cognitive linguistics

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Authors: Kathryn Redmond, Mojdeh Asadollahi Pajouh, Grace Panther, Rick Evans, Stacey Kulesza, Jia Liang

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An on-going focus in engineering education research is on increasing the number of women in engineering. While the number of women participating in engineering project teams has increased over the past five years, the number of women enrolled in engineering colleges remains stagnant. Previous studies have explored why the number of women enrolled in engineering colleges remains small. In doing so, researchers focused primarily on negative experiences women encountered. Instead of looking at negative experiences, which can further deter women from entering the field, the aim of this study is to explore the personal and institutional factors that allow women to succeed and thrive in undergraduate engineering programs. There are two research questions addressed in this paper. The first is: what are the personal traits and characteristics that allow women to thrive in engineering? The other is: what are the institutional policies and culture, as well as micro-level behaviors on project teams, that influence the environment for women to thrive in engineering? Two women studying engineering at an R1 university were interviewed. Each woman was interviewed three times for a total of six interviews. The phenomenographic interviews focused on the lived experiences of the participants to better understand thriving in engineering. The first interview focused on the women’s personal life and background, the second on their learning journey and project team experiences, and the third focused on videos the women took through a method called Photovoice. Interviews were transcribed, and an inductive thematic analysis was conducted. Four themes were identified. Multiple coders were utilized to ensure trustworthiness and increase interrater reliability. Results indicate that thriving women have supportive families, experienced gender biases, and enjoy hands-on engineering and creating a final product. These traits and experiences may help inspire younger women to pursue engineering degrees and can help inform institutions as they make policy changes to support women. Additional women will be recruited from four different universities to further develop a theoretical framework to help inform institutions in how they can support women to thrive in engineering.

Keywords: diversity, inclusion, project teams, women in engineering

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Authors: Marzieh Khezerloo, Lyazid Djenidi

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Owing to wide range of the micro-device applications, the problems of mixing at small scales is of significant interest. Also, because most of the processes produce heat, it is needed to develop and implement strategies for heat removal in these devices. There are many studies which focus on the effect of roughness or suction on heat transfer performance, separately, although it would be useful to take advantage of these two methods to improve heat transfer performance. Unfortunately, there is a gap in this area. The present numerical study is carried to investigate the combined effects of roughness and wall suction on heat transfer performance of a laminar channel flow; suction is applied on the top and back faces of the roughness element, respectively. The study is carried out for different Reynolds numbers, different suction rates, and various locations of suction area on the roughness. The flow is assumed two dimensional, incompressible, laminar, and steady state. The governing Navier-Stokes equations are solved using ANSYS-Fluent 18.2 software. The present results are tested against previous theoretical results. The results show that by adding suction, the local Nusselt number is enhanced in the channel. In addition, it is shown that by applying suction on the bottom section of the roughness back face, one can reduce the thickness of thermal boundary layer, which leads to an increase in local Nusselt number. This indicates that suction is an effective means for improving the heat transfer rate (suction by controls the thickness of thermal boundary layer). It is also shown that the size and intensity of vortical motion behind the roughness element, decreased with an increasing suction rate, which leads to higher local Nusselt number. So, it can be concluded that by using suction, strategically located on the roughness element, one can control both the recirculation region and the heat transfer rate. Further results will be presented at the conference for coefficient of drag and the effect of adding more roughness elements.

Keywords: heat transfer, laminar flow, numerical simulation, roughness, suction

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Authors: E. Nakamachi, S. Tanaka, K. Yamamoto, Y. Morita

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In this study, we developed a three-dimensional (3D) direct current electric field (DCEF) stimulation bio-reactor for axonal outgrowth enhancement to generate the neural network of the central nervous system (CNS). By using our newly developed 3D DCEF stimulation bio-reactor, we cultured the rat pheochromocytoma cells (PC12) and investigated the effects on the axonal extension enhancement and network generation. Firstly, we designed and fabricated a 3D bio-reactor, which can load DCEF stimulation on PC12 cells embedded in the collagen gel as extracellular environment. The connection between the electrolyte and the medium using salt bridges for DCEF stimulation was introduced to avoid the cell death by the toxicity of metal ion. The distance between the salt bridges was adopted as the design variable to optimize a structure for uniform DCEF stimulation, where the finite element (FE) analyses results were used. Uniform DCEF strength and electric flux vector direction in the PC12 cells embedded in collagen gel were examined through measurements of the fabricated 3D bio-reactor chamber. Measurement results of DCEF strength in the bio-reactor showed a good agreement with FE results. In addition, the perfusion system was attached to maintain pH 7.2 ~ 7.6 of the medium because pH change was caused by DCEF stimulation loading. Secondly, we disseminated PC12 cells in collagen gel and carried out 3D culture. Finally, we measured the morphology of PC12 cell bodies and neurites by the multiphoton excitation fluorescence microscope (MPM). The effectiveness of DCEF stimulation to enhance the axonal outgrowth and the neural network generation was investigated. We confirmed that both an increase of mean axonal length and axogenesis rate of PC12, which have been exposed 5 mV/mm for 6 hours a day for 4 days in the bioreactor. We found following conclusions in our study. 1) Design and fabrication of DCEF stimulation bio-reactor capable of 3D culture nerve cell were completed. A uniform electric field strength of average value of 17 mV/mm within the 1.2% error range was confirmed by using FE analyses, after the structure determination through the optimization process. In addition, we attached a perfusion system capable of suppressing the pH change of the culture solution due to DCEF stimulation loading. 2) Evaluation of DCEF stimulation effects on PC12 cell activity was executed. The 3D culture of PC 12 was carried out adopting the embedding culture method using collagen gel as a scaffold for four days under the condition of 5.0 mV/mm and 10mV/mm. There was a significant effect on the enhancement of axonal extension, as 11.3% increase in an average length, and the increase of axogenesis rate. On the other hand, no effects on the orientation of axon against the DCEF flux direction was observed. Further, the network generation was enhanced to connect longer distance between the target neighbor cells by DCEF stimulation.

Keywords: PC12, DCEF stimulation, 3D bio-reactor, axonal extension, neural network generation

Procedia PDF Downloads 184

Authors: Sarmistha Baruah, Akshai Kumar, Nageswara Rao Peela

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The global energy crisis due to the dependence on fossil fuels and its limited reserves as well as environmental pollution are key concerns to the research communities. However, the implementation of alcohol-based fuel cells such as methanol is anticipated as a reliable source of future energy technology due to their high energy density, environment friendliness, ease of storage, transportation, etc. To drive the anodic methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs), an active and long-lasting catalyst is necessary for efficient energy conversion from methanol. Recently, transition metal-zeolite-based materials have been considered versatile catalysts for a variety of industrial and lab-scale processes. Large specific surface area, well-organized micropores, and adjustable acidity/basicity are characteristics of zeolites that make them excellent supports for immobilizing small-sized and highly dispersed metal species. Significant advancement in the production and characterization of well-defined metal clusters encapsulated within zeolite matrix has substantially expanded the library of materials available, and consequently, their catalytic efficacy. In this context, we developed bimetallic Ni-Co catalysts encapsulated within LTA (also known as 4A) zeolite via a method combined with the in-situ encapsulation of metal species using hydrothermal treatment followed by a chemical reduction process. The prepared catalyst was characterized using advanced characterization techniques, such as X-ray diffraction (XRD), field emission transmission electron microscope (FETEM), field emission scanning electron microscope (FESEM), energy dispersive X-ray (EDX), and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activity of the catalyst for MOR was carried out in an alkaline medium at room temperature using techniques such as cyclic voltammetry (CV), and chronoamperometry (CA). The resulting catalyst exhibited better catalytic activity of 12.1 mA cm-2 at 1.12 V vs Ag/AgCl and retained remarkable stability (~77%) even after 1000 cycles CV test for the electro-oxidation of methanol in alkaline media without any significant microstructural changes. The high surface area, better Ni-Co species integration in the zeolite, and the ample amount of surface hydroxyl groups contribute to highly dispersed active sites and quick analyte diffusion, which provide notable MOR kinetics. Thus, this study will open up new possibilities to develop a noble metal-free zeolite-based electrocatalyst due to its simple synthesis steps, large-scale fabrication, improved stability, and efficient activity for DMFC application.

Keywords: alkaline media, bimetallic, encapsulation, methanol oxidation reaction, LTA zeolite.

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Authors: Moetazza M. Alshafei, Ahmed M. Mabrouk, Emtenan M. Hanafi, Manal M. Ramadan, Reda M. S. Korany, Seham S. Kassem, Dina Mostafa Mohammed

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Metabolic syndrome (MeS) is a major health problem with a high incidence of obese individuals worldwide. Increased related morbidity of diabetes, hypertension and fatty liver disease, and complicated cardiovascular disease are inevitable. Boswellia serrata gum (Bos) is a promising traditional medicinal plant; it has several pharmacological properties, including anti-inflammatory, antioxidant, and antilipase activities. Probiotics (Bac) supplements have good benefits on health and MeS, whether it is supplemented in combination with prebiotics or alone. Microencapsulation helps to mask unpalatable taste and odor and deliver active ingredients to targeted organs. Methodology MeS rat model was produced by feeding rats with a high fat, high CHO diet (HFD). Bos was extracted, and both Bos and the probiotic were microencapsulated with a spray drier. Female rats were divided into 5 groups (N8). HFD control, control normal receiving basic diet, HFD treated, from the start of the experiment, either with encapsulated Bos, Bac and Bos or Bac only, all treatments were received for eight weeks (after approval from NRC animal ethical committee). Serum was collected to analyze lipid profile, blood sugar, liver and kidney functions, antioxidants, leptin, and progesterone. Rat's organs and body fat were weighed and collected for histopathology. Statistical analysis was done by use of one way Anova test in the SPSS program. Results showed control of elevated body weight, lipid profile, and glucose levels as well as decrease of body fat index and improvement of histopathology of liver and heart, especially in combination. Conclusion: We concluded that both microencapsulated Bos and probiotics have a controlling effect on MeS parameters.

Keywords: metabolic syndrome, Boswellia serata, probiotic, micro-encapsulation, histopathology, liver steatosis

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Authors: Mohammad Altaf Hossain

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A growing body of literature in urban studies has presented that urban precarity has been a lived experience for low-income groups of people in the cities of the Global South. It does not necessarily mean that cities in the Global North, where advanced capitalist economies exist, avoided the adverse realities of urban precarity. As a multifaceted condition, it creates other associated precariousness in lives -for example, economic deprivation, mental stress, and housing precarity. The interrelations between urbanity and precarity have been ubiquitous regardless of the developed and developing countries. People, mainly manual labourers with low incomes, go through uncertainties in every aspect of life. By analysing qualitative data and embracing structure-agency interaction, this paper intends to present how Bangladeshi migrants experience housing precarity in Dublin. Continued population growth and political economy factors such as labour market inequality, financialisation of the private rental sector, and the impact of cuts to government funding for social housing provision are combined to produce a housing supply crisis, affordability, and access in the city. As a result, low-income people practice informality in securing jobs and housing. The macro-structural components of this analysis include the Irish housing policy, the European labour market, the immigration policy, and the financialised housing market. The micro-structural components of South Asian communities’ experiences include social networks and social class. Access to social networks and practices of informality play a significant role in enabling them to negotiate urban precarity, including housing crises and income insecurity. In some cases, the collective agency of ethnic diaspora communities plays a vital role in negotiating with structural constraints.

Keywords: housing precarity, housing pathways, migration, agency, Dublin

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Authors: Rameh Chauhan

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Tunnel construction in Himalayan rock is a challenging task due to fragile nature of the strata. Tunnel excavation carried out from lower Himalayas to high Himalayas in different metamorphic rock. Therefore application of engineering geology plays a vital role during various stage of the tunneling projects. Engineering geology is defined as application of geology to construction of civil structures through engineering practice. It is applied to the design, construction and performance aspects of engineering structure on the surface or sub-surface like dam, underground and surface power house, cut slopes, tunnels and underground storage cavern for nuclear material. But this paper emphasized mostly on underground structures like big caverns of Power house, desilting chambers, and tunnels of various sizes. Construction of these structures in the fragile rock conditions of Himalayan geology from Western Himalayas to Eastern Himalayas necessitated the application of the engineering geology on the micro-scale base for the stability, performance, and longevity of the civil structures. Number of hydropower projects have been constructed, some of them are under construction and under investigation stage. These projects are located in various parts of Himalayas under various seismic-tectonic zones. Tunneling works are involved in these projects. This paper represents the various engineering geological practices adopted in investigation and construction stage of various projects based on experiences gained during past construction histories in Himalayan geology of young mountains in very fragile geological conditions. Highlighting and sharing of use of these techniques on various platforms will definitely enhance the knowledge for carrying out the construction of various projects for the development of society. Construction of the tunnels, surface, and sub-surface caverns, dams, highway, metro, highway tunnels are all based on engineering geological parameters in combinations with other engineering considerations.

Keywords: cavern-power house, desilting chambers and tunnels, seismic-tectonic-zones, earthquake-prone zones based on intensities

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Authors: Varun A Baheti, Sanjay Kashyap, Kamanio Chattopadhyay, Praveen Kumar, Aloke Paul

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Ni–Sn system finds applications in the microelectronics industry, especially with respect to flip–chip or direct chip, attach technology. Here the region of interest is under bump metallization (UBM), and solder bump (Sn) interface due to the formation of brittle intermetallic phases there. Understanding the growth of these phases at UBM/Sn interface is important, as in many cases it controls the electro–mechanical properties of the product. Cu and Ni are the commonly used UBM materials. Cu is used for good bonding because of fast reaction with solder and Ni often acts as a diffusion barrier layer due to its inherently slower reaction kinetics with Sn–based solders. Investigation on the growth kinetics of phases in Ni–Sn system is reported in this study. Just for simplicity, Sn being major solder constituent is chosen. Ni–Sn electroplated diffusion couples are prepared by electroplating pure Sn on Ni substrate. Bulk diffusion couples prepared by the conventional method are also studied along with Ni–Sn electroplated diffusion couples. Diffusion couples are annealed for 25–1000 h at 50–215°C to study the phase evolutions and growth kinetics of various phases. The interdiffusion zone was analysed using field emission gun equipped scanning electron microscope (FE–SEM) for imaging. Indexing of selected area diffraction (SAD) patterns obtained from transmission electron microscope (TEM) and composition measurements done in electron probe micro−analyser (FE–EPMA) confirms the presence of various product phases grown across the interdiffusion zone. Time-dependent experiments indicate diffusion controlled growth of the product phase. The estimated activation energy in the temperature range 125–215°C for parabolic growth constants (and hence integrated interdiffusion coefficients) of the Ni₃Sn₄ phase shed light on the growth mechanism of the phase; whether its grain boundary controlled or lattice controlled diffusion. The location of the Kirkendall marker plane indicates that the Ni₃Sn₄ phase grows mainly by diffusion of Sn in the binary Ni–Sn system.

Keywords: diffusion, equilibrium phase, metastable phase, the Ni-Sn system

Procedia PDF Downloads 307

Authors: Ghada Ben Hamad, Zohir Younsi, Hassane Naji, Noureddine Lebaz, Naoual Belouaggadia

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This study deals with a bifunctional micro-encapsulated phase change (MCP) material, capric-stearic acid/graphene oxide-TiO2, which has been successfully developed by in situ hydrolysis and polycondensation of tetrabutyl titanate and modification of graphene oxide (GO) on the TiO2 doped shell. The use of graphene and doped TiO2 is a promising approach to provide photocatalytic activity under visible light and improve the microcapsules physicochemical properties. The morphology and chemical structure of the resulting microcapsule samples were determined by using Fourier transform infrared (FT-IR) spectroscopy, scanning electronic microscope (SEM), and X-ray diffractometer (XRD) methods. The ultraviolet, visible spectrophotometer (UV–vis), the differential scanning calorimeter (DSC) and the thermogravimetric analyzer (TGA) were used to investigate the absorption of visible and ultraviolet (UV), the thermal properties, and thermal stabilities of the microcapsules. Note that, the visible light photocatalytic activity was assessed for the toluene and benzene gaseous removal in a suitable test room. The microcapsules exhibit an interesting spherical morphology and an average diameter of 15 to 25 μm. The addition of graphene can enhance the rigidity of the shell and improve the microcapsules thermal reliability. At the same time, the thermal analysis tests showed that the synthesized microcapsules had a high solar thermal energy-storage and better thermal stability. In addition, the capric-stearic acid microcapsules exhibited high solar photocatalytic activity with respect to atmospheric pollutants under natural sunlight. The fatty acid samples obtained with the GO/TiO2 shell showed great potential for applications of solar energy storage, solar photocatalytic degradation of air pollutants and buildings energy conservation.

Keywords: thermal energy storage, microencapsulation, titanium dioxide, photocatalysis, graphene oxide

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Authors: Sue Hershberger Yoder, Jon Yoder

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“The appearance does not hide the essence, it reveals it; it is the essence.”—Jean-Paul Sartre, Being and Nothingness Three decades ago, transarchitect Marcos Novak developed an early form of algorithmic animation he called “liquid architecture.” In that project, digitally floating forms morphed seamlessly in cyberspace without claiming to evolve or improve. Change itself was seen as inevitable. And although some imagistic moments certainly stood out, none was hierarchically privileged over another. That project challenged longstanding assumptions about creativity and artistic genius by posing infinite parametric possibilities as inviting alternatives to traditional notions of stability, originality, and evolution. Through ephemeral processes of printing, milling, and projecting, the exhibition “Liquid Illumination” destabilizes the solid foundations of fashion and architecture. The installation is neither worn nor built in the conventional sense, but—like the sensual art forms of fashion and architecture—it is still radically embodied through the logics and techniques of design. Appearances are everything. Surface pattern and color are no longer understood as minor afterthoughts or vapid carriers of dubious content. Here, they become essential but ever-changing aspects of precisely fabricated images. Fourteen silk “colorways” (a term from the fashion industry) are framed selections from ongoing experiments with intricate pattern and complex color configurations. Whether these images are printed on fabric, milled in foam, or illuminated through projection, they explore and celebrate the untapped potentials of the surficial and superficial. Some components of individual prints appear to float in front of others through stereoscopic superimpositions; some figures appear to melt into others due to subtle changes in hue without corresponding changes in value; and some layers appear to vibrate via moiré effects that emerge from unexpected pattern and color combinations. The liturgical atmosphere of Liquid Illumination is intended to acknowledge that, like the simultaneously sacred and superficial qualities of rose windows and illuminated manuscripts, artistic and religious ideologies are also always malleable. The intellectual provocation of this paper pushes the boundaries of current thinking concerning viable applications for fashion print designs and architectural images—challenging traditional boundaries between fine art and design. The opportunistic installation of digital printing, CNC milling, and video projection mapping in a gallery that is normally reserved for fine art exhibitions raises important questions about cultural/commercial display, mass customization, digital reproduction, and the increasing prominence of surface effects (color, texture, pattern, reflection, saturation, etc.) across a range of artistic practices and design disciplines.

Keywords: fashion, print design, architecture, projection mapping, image, fabrication

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Authors: B. J. Babalola, M. B. Shongwe

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Spark Plasma Sintering technique is a novel processing method that produces limited grain growth and highly dense variety of materials; alloys, superalloys, and carbides just to mention a few. However, initial particle size and spark plasma sintering parameters are factors which influence the grain growth and mechanical properties of sintered materials. Ni-Cr alloys are regarded as the most promising alloys for aerospace turbine blades, owing to the fact that they meet the basic requirements of desirable mechanical strength at high temperatures and good resistance to oxidation. The conventional method of producing this alloy often results in excessive grain growth and porosity levels that are detrimental to its mechanical properties. The effect of sintering temperature was evaluated on the microstructure and mechanical properties of the nanostructured Ni-17Cr alloy. Nickel and chromium powder were milled using high energy ball milling independently for 30 hours, milling speed of 400 revs/min and ball to powder ratio (BPR) of 10:1. The milled powders were mixed in the composition of Nickel having 83 wt % and chromium, 17 wt %. This was sintered at varied temperatures from 800°C, 900°C, 1000°C, 1100°C and 1200°C. The structural characteristics such as porosity, grain size, fracture surface and hardness were analyzed by scan electron microscopy and X-ray diffraction, Archimedes densitometry, micro-hardness tester. The corresponding results indicated an increase in the densification and hardness property of the alloy as the temperature increases. The residual porosity of the alloy reduces with respect to the sintering temperature and in contrast, the grain size was enhanced. The study of the mechanical properties, including hardness, densification shows that optimum properties were obtained for the sintering temperature of 1100°C. The advantages of high sinterability of Ni-17Cr alloy using milled powders and microstructural details were discussed.

Keywords: densification, grain growth, milling, nanostructured materials, sintering temperature

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Authors: Pravin Kumar, Rajendra K. Singh, Prabhakar Singh

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A widespread research work on Mo-based double perovskite systems has been reported as a potential application for electrode materials of solid oxide fuel cells. Mo-based double perovskites studied in form of B-site ordered double perovskite materials, with general formula A₂B′B″O₆ structured by alkaline earth element (A = Sr, Ca, Ba) and heterovalent transition metals (B′ = Fe, Co, Ni, Cr, etc. and B″ = Mo, W, etc.), are raising a significant interest as potential mixed ionic-electronic conductors in the temperature range of 500-800 °C. Such systems reveal higher electrical conductivity, particularly those assigned in form of Sr₂CoMoO₆₋δ (M = Mg, Mn, Fe, Co, Ni, Zn etc.) which were studied in different environments (air/H₂/H₂-Ar/CH₄) at an intermediate temperature. Among them, the Sr₂CoMoO₆₋δ system is a potential candidate as an anode material for solid oxide fuel cells (SOFCs) due to its better electrical conductivity. Therefore, Sr₂CoMoO₆₋δ (SCM) system with La-doped on Sr site has been studied to discover the structural and electrical properties. The double perovskite system Sr₂CoMoO₆₋δ (SCM) and doped system Sr₂-ₓLaₓCoMoO₆₋δ (SLCM, x=0.04) were synthesized by the citrate-nitrate combustion synthesis route. Thermal studies were carried out by thermo-gravimetric analysis. Phase justification was confirmed by powder X-ray diffraction (XRD) as a tetragonal structure with space group I4/m. A minor phase of SrMoO₄ (s.g. I41/a) was identified as a secondary phase using JCPDS card no. 85-0586. Micro-structural investigations revealed the formation of uniform grains. The average grain size of undoped (SCM) and doped (SLCM) compositions was calculated by a linear intercept method and found to be ⁓3.8 μm and 2.7 μm, respectively. The electrical conductivity of SLCM is found higher than SCM in the air within the temperature range of 200-600 °C. SLCM system was also measured in reducing atmosphere (pure H₂) in the temperature range 300-600 °C. SLCM has been showed the higher conductivity in the reducing atmosphere (H₂) than in air and therefore it could be a promising anode material for SOFCs.

Keywords: double perovskite, electrical conductivity, SEM, XRD

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Authors: Shivani Dolas, A. Richa Mishra

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The existence of Courtyards in India can be traced back to ‘Indus valley civilization’ and various layers of history bearing implications like socio-cultural, traditional, religious, climatic, etc., moreover serving as a breathing space in case of historical core areas. Over time, with the overlay of various historic layers within the historic urban cores and the present high density populace, the cores are getting congested day by day. In this case, courtyards may emerge out as an efficient medium to provide quality of life through livable spaces. Presently, with the growing population of the historic town of Gwalior, town in Madhya Pradesh holds remarkable essence of courtyards with its multiple concepts over time. Its scale and function varies from an imposing grand appearance in palatial form, up to functional practices as residential. Its privilege can also be drawn in urban forms, in sharing single space by multiple dwellings and in temples which can be sketched specifically in the region. Moreover, the effectiveness of courtyards has proven balance and control of micro-climate in such composite climate region. The research paper aims to underline the concept of courtyards in case of a mixed use neighborhood, Naya bazar, in Lashkar area of Gwalior, which developed during 19th century, highlighting the need of its preservation. The paper also elaborates its various implications on user-space relationship as in the present context, and growing congestion in the area, user and space relationship is seen lost. The noticeable change in the behavioral context in buildings and users can be noticed with the downfall of courtyards, isolating users with land. Also, a concern has been expressed on negligence of courtyard planning in future development, suggesting recommendations on preserving the courtyard typology as heritage.

Keywords: courtyards, Gwalior, historic settlement, heritage

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Authors: Rima Almalla

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The purpose of the research project in Geography is to evaluate the applicability of urban green infrastructure approach in Finnish climate. The key focus will be on the operation and efficiency of green infrastructure on urban stormwater management. Green infrastructure approach refers to the employment of sufficient green covers as a modern and smart environmental solution to improve the quality of urban environments. Green infrastructure provides a wide variety of micro-scale ecosystem services, such as stormwater runoff management, regulation of extreme air temperatures, reduction of energy consumption, plus a variety of social benefits and human health and wellbeing. However, the cold climate of Finland with seasonal ground frost, snow cover and relatively short growing season bring about questions of whether green infrastructure works as efficiently as expected. To tackle this question, green infrastructure solutions will be studied and analyzed with manifold methods: stakeholder perspectives regarding existing and planned GI solutions will be collected by web based questionnaires, semi structured interviews and group discussions, and analyzed in both qualitative and quantitative methods. Targeted empirical field campaigns will be conducted on selected sites. A systematic literature review with global perspective will support the analyses. The findings will be collected, compiled and analyzed using geographic information systems (GIS). The findings of the research will improve our understanding of the functioning of green infrastructure in the Finnish environment in urban stormwater management, as a landscape element for citizens’ wellbeing, and in climate change mitigation and adaptation. The acquired information will be shared with stakeholders in interactive co-design workshops. As green covers have great demand and potential globally, the conclusions will have relevance in other cool climate regions and may support Finnish business in green infrastructure sector.

Keywords: climate change adaptation, climate change, green infrastructure, stormwater

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Authors: Aleksander Ejsmont, Stefan Wuttke, Joanna Goscianska

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Gaining control over particle shape, size and crystallinity is an ongoing challenge for many materials. Especially metalorganic frameworks (MOFs) are recently widely studied. Besides their remarkable porosity and interesting topologies, morphology has proven to be a significant feature. It can affect the further material application. Thus seeking new approaches that enable MOF morphology modulation is important. MOFs are reticular structures, where building blocks are made up of organic linkers and metallic nodes. The most common strategy of ensuring metal source is using salts, which usually exhibit high solubility and hinder morphology control. However, there has been a growing interest in using metal oxides as structure-directing agents towards MOFs due to their very low solubility and shape preservation. Metal oxides can be treated as a metal reservoir during MOF synthesis. Up to now, reports in which receiving MOFs from metal oxides mostly present ZnO conversion to ZIF-8. However, there are other oxides, for instance, Co₃O₄, which often is overlooked due to their structural stability and insolubility in aqueous solutions. Cobalt-based materials are famed for catalytic activity. Therefore the development of their efficient synthesis is worth attention. In the presented work, an optimized Co₃O₄transition to Co-MOFviaa solvothermal approach was proposed. The starting point of the research was the synthesis of Co₃O₄ flower petals and needles under hydrothermal conditions using different cobalt salts (e.g., cobalt(II) chloride and cobalt(II) nitrate), in the presence of urea, and hexadecyltrimethylammonium bromide (CTAB) surfactant as a capping agent. After receiving cobalt hydroxide, the calcination process was performed at various temperatures (300–500 °C). Then cobalt oxides as a source of cobalt cations were subjected to reaction with trimesic acid in solvothermal environment and temperature of 120 °C leading to Co-MOF fabrication. The solution maintained in the system was a mixture of water, dimethylformamide, and ethanol, with the addition of strong acids (HF and HNO₃). To establish how solvents affect metal oxide conversion, several different solvent ratios were also applied. The materials received were characterized with analytical techniques, including X-ray powder diffraction, energy dispersive spectroscopy,low-temperature nitrogen adsorption/desorption, scanning, and transmission electron microscopy. It was confirmed that the synthetic routes have led to the formation of Co₃O₄ and Co-based MOF varied in shape and size of particles. The diffractograms showed receiving crystalline phase for Co₃O₄, and also for Co-MOF. The Co₃O₄ obtained from nitrates and with using low-temperature calcination resulted in smaller particles. The study indicated that cobalt oxide particles of different size influence the efficiency of conversion and morphology of Co-MOF. The highest conversion was achieved using metal oxides with small crystallites.

Keywords: Co-MOF, solvothermal synthesis, morphology control, core-shell

Procedia PDF Downloads 162