Search results for: chemical segregation

Authors: Amitkumar Barot, Vijaykumar Sinha

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There is growing interest in the development of new materials based on recycled polymers from plastic waste, and also in the field of lubricants much effort has been spent on substitution of petro-based raw materials by natural-based renewable ones. This is due to the facts of depleting fossil fuels and due to strict environmental laws. In relevance to this, new technique for the formulation of grease that combines the chemical recycling of poly (ethylene terephthalate) PET with the use of castor oil (CO) has been developed. Comparison to diols used in chemical recycling of PET, castor oil is renewable, easily available, environmentally friendly, economically cheaper and hence sustainability indeed. The process parameters like CO concentration and temperature were altered, and further, the influences of the process parameters have been studied in order to establish technically and commercially viable process. Further thereby formed depolymerized product find an application as base oil in the formulation of grease. A depolymerized product has been characterized by various chemical and instrumental methods, while formulated greases have been evaluated for its tribological properties. The grease formulated using this new environmentally friendly approach presents applicative properties similar, and in some cases superior, compared to those of a commercial grease obtained from non-renewable resources.

Keywords: castor oil, grease formulation, recycling, sustainability

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Authors: Geminne Manzano, Porfirio Aliño, Clairecynth Yu, Lilibeth Salvador-Reyes, Viviene Santiago

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Many marine benthic organisms produce secondary metabolites that serve as ecological roles to different biological and environmental factors. The secondary metabolites found in these organisms like algae, sponges, tunicates and worms exhibit variation at different scales. Understanding the chemical variation can be essential in deriving the evolutionary and ecological function of the secondary metabolites that may explain their patterns. Ecological surveys were performed on two collection sites representing from two Philippine marine biogeographic regions – in Oriental Mindoro located on the West Philippine Sea (WPS) and in Zamboanga del Sur located at Celebes Sea (CS), where a total of 39 Xestospongia sp. sponges were collected using SCUBA. The sponge samples were transported to the laboratory for taxonomic identification and chemical analysis. Biological and environmental factors were investigated to determine their relation to the abundance and distribution patterns and its spatial variability of their secondary metabolite production. Extracts were subjected to thin-layer chromatography and anti-proliferative assays to confirm the presence of Renieramycin-M and to test its cytotoxicity. The blue sponges were found to be more abundant on the WPS than in CS. Both the benthic community and the fish community in Oriental Mindoro, WPS and Zamboanga del Sur, CS sites are characterized by high species diversity and abundance and a very high biomass category. Environmental factors like depth and monsoonal exposure were also compared showing that wave exposure and depth are associated with the abundance and distribution of the sponges. Renieramycin-M presence using the TLC profiles between the sponge extracts from WPS and from CS showed differences in the Reniermycin-M presence and the presence of other functional groups were observed between the two sites. In terms of bioactivity, different responses were also exhibited by the sponge extracts coming from the different region. Different responses were also noted on its bioactivity depending on the cell lines tested. Exploring the influence of ecological parameters on the chemical variation can provide deeper chemical ecological insights in the knowledge and their potential varied applications at different scales. The results of this study provide further impetus in pursuing studies into patterns and processes of the chemical diversity of the Philippine blue sponge, Xestospongia sp. and the chemical ecological significance of the coral triangle.

Keywords: chemical ecology, porifera, renieramycin-m, spatial variability, Xestospongia sp.

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Authors: Alazar G. Ejigu

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Cities have traditionally been designed for and by men. Despite positive changes in this regard, contemporary cities appear to offer limited options and experiences to women in their everyday life. There are differences regarding the quality of space. Distressed or disadvantaged areas often have less access to urban qualities, such as services, parks, and public places, than more privileged ones. The most attractive meeting-places are located centrally, whereas many suburban areas lack these elements. By focusing on young women living in multi-ethnic working-class suburban areas in Stockholm - a group generally ignored and disadvantaged; the study aims to examine various forms of inequality or equality in three selected neighborhoods. Spatial data was collected through walk-along with the young girls, inventory of the places, and geodata made available by Statistics Sweden (SCB). The combined data was analyzed with the help of Geographic Information Systems (GIS). In line with Crenshaw - one of the forerunners of intersectional thinking – the project departs from the idea that if we address the needs of those who are disadvantaged and restructure urban space accordingly, then others will benefit too. Thus, working our way towards a more equal city.

Keywords: GIS, segregation, gender equality, urban planning

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Authors: Enayat Enayati, Reza Behtash

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The purpose of the H2 removal system is to reduce a content of hydrogen and other combustibles in the CO2 feed owing to avoid developing a possible explosive condition in the synthesis. In order to reduce the possibility of forming an explosive gas mixture in the synthesis as much as possible, the hydrogen percent in the fresh CO2, will be removed in hydrogen converter. Therefore the partly compressed CO2/Air mixture is led through Hydrogen converter (Reactor) where the H2, present in the CO2, is reduced by catalytic combustion to values less than 50 ppm (vol). According the following exothermic chemical reaction: 2H2 + O2 → 2H2O + Heat. The catalyst in hydrogen converter consist of platinum on a aluminum oxide carrier. Low catalyst activity maybe due to catalyst poisoning. This will result in an increase of the hydrogen content in the CO2 to the synthesis. It is advised to shut down the plant when the outlet of hydrogen converter increased above 100 ppm, to prevent undesirable gas composition in the plant. Replacement of catalyst will be time exhausting and costly so as to prevent this, we increase the inlet temperature of hydrogen converter according to following Arrhenius' equation: K=K0e (-E_a/RT) K is rate constant of a chemical reaction where K0 is the pre-exponential factor, E_a is the activation energy, and R is the universal gas constant. Increment of inlet temperature of hydrogen converter caused to increase the rate constant of chemical reaction and so declining the amount of hydrogen from 125 ppm to 70 ppm.

Keywords: catalyst, converter, poisoning, temperature

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Authors: El Alia Boularas, H. Bekkar, H. Larachi, H. Rezk-kallah

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Introduction: Notwithstanding cosmetics are used in life every day, these products are not all innocuous and harmless, as they may contain ingredients responsible for allergic reactions and, possibly, for other health problems. Additionally, environmental pollution should be taken into account. Thus, it is time to investigate what is ‘hidden behind beauty’. Aims: 1.To investigate prevalence of 13 chemical ingredients in cosmetics being object of concern, which the Algerians use regularly. 2.To know the profile of questioned consumers and describe their opinion on cosmetics. Methods: The survey was carried out in year 2013 over a period of 3 months, among Algerian Internet users having an e-mail address or a Facebook account.The study investigated 13 chemical agents showing health and environmental problems, selected after analysis of the recent studies published on the subject, the lists of national and international regulatory references on chemical hazards, and querying the database Skin Deep presented by the Environmental Working Group. Results: 300 people distributed all over the Algerian territory participated in the survey, providing information about 731 cosmetics; 86% aged from 20 to 39 years, with a sex ratio=0,27. A percentage of 43% of the analyzed cosmetics contained at least one of the 13 toxic ingredients. The targeted ingredient that has been most frequently reported was ‘perfume’ followed by parabens and PEG.85% of the participants declared that cosmetics ‘can contain toxic substances’, 27% asserted that they verify regularly the list of ingredients when they buy cosmetics, 61% said that they try to avoid the toxic ingredients, among whom 24 % were more vigilant on the presence of parabens, 95% were in favour of the strengthening of the Algerian laws on cosmetics. Conclusion: The results of the survey provide the indication of a widespread presence of toxic chemical ingredients in personal care products that Algerians use daily.

Keywords: Algerians consumers, cosmetics, survey, toxic ingredients

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Authors: Xin Wu, Yongfeng Zhao, Qingxiang Meng

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In China, quite low proportion of crop residues were used as feedstuff because of its poor palatability and low digestibility. Steam explosion is a physical and chemical feed processing technology which has great potential to improve sapidity and digestibility of crop residues. To investigate the effect of the steam explosion on chemical compositions and efficient energy values, crop residues (rice straw, wheat straw and maize stover) were processed by steam explosion (steam temperature 120-230°C, steam pressure 2-26kg/cm², 40min). Steam-exploded crop residues were regarded as treatment groups and untreated ones as control groups, nutritive compositions were analyzed and effective energy values were calculated by prediction model in INRA (1988, 2010) for both groups. Results indicated that the interaction between treatment and variety has a significant effect on chemical compositions of crop residues. Steam explosion treatment of crop residues decreased neutral detergent fiber (NDF) significantly (P < 0.01), and compared with untreated material, NDF content of rice straw, wheat straw, and maize stover lowered 21.46%, 32.11%, 28.34% respectively. Acid detergent lignin (ADL) of crop residues increased significantly after the steam explosion (P < 0.05). The content of crude protein (CP), ether extract (EE) and Ash increased significantly after steam explosion (P < 0.05). Moreover, predicted effective energy values of each steam-exploded residue were higher than that of untreated ones. The digestible energy (DE), metabolizable energy (ME), net energy for maintenance (NEm) and net energy for gain (NEg)of steam-exploded rice straw were 3.06, 2.48, 1.48and 0.29 MJ/kg respectively and increased 46.21%, 46.25%, 49.56% and 110.92% compared with untreated ones(P < 0.05). Correspondingly, the energy values of steam-exploded wheat straw were 2.18, 1.76, 1.03 and 0.15 MJ/kg, which were 261.78%, 261.29%, 274.59% and 1014.69% greater than that of wheat straw (P < 0.05). The above predicted energy values of steam exploded maize stover were 5.28, 4.30, 2.67 and 0.82 MJ/kg and raised 109.58%, 107.71%, 122.57% and 332.64% compared with the raw material(P < 0.05). In conclusion, steam explosion treatment could significantly decrease NDF content, increase ADL, CP, EE, Ash content and effective energy values of crop residues. The effect of steam explosion was much more obvious for wheat straw than the other two kinds of residues under the same condition.

Keywords: chemical compositions, crop residues, efficient energy values, steam explosion

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Authors: Yusser Olguín, Diego Benavente, Fernando Dorta, Nicole Orellana, Cristian Acevedo

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One of the greatest challenges of tissue engineering is the generation of materials in which the highest possible number of conditions can be incorporated to stimulate the proliferation and differentiation of cells, which will be transformed together with the material into new functional tissue. In this sense, considering the properties of microfluidics and its relationship with cellular micro-environments, the possibility of controlling flow patterns and the ability to design diverse patterns in the chips, a microfluidic cell culture system can be established as a means for the evaluation of the effect of different parameters in a controlled and precise manner. Specifically in relation to the study and development of alternatives in peripheral nervous tissue engineering, it is necessary to consider different physical and chemical neurotrophic stimuli that promote cell growth and differentiation. Chemical stimuli include certain vitamins, glucocorticoids, gangliosides, and growth factors, while physical stimuli include topological stimuli, mechanical forces of the cellular environment and electrical stimulation. In this context, the present investigation shows the results of cell stimulation in a microbioreactor using electrical and chemical stimuli, where the differentiation of PC12 cells as a neuronal model is evidenced by neurite expression, dependent on the stimuli and their combination. The results were analysed with a multi-factor statistical approach, showing several relationships and dependencies between different parameters. Chip design, operating parameters and concentrations of neurotrophic chemical factors were found to be preponderant, based on the characteristics of the electrical stimuli.

Keywords: microfluidics, nerve tissue engineering, microbioreactor, electrical stimuli

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Authors: S. Stankov, H. Fidan, N. Petkova, M. Stoyanova, Tz. Radoukova, A. Stoyanova

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The aim of this study was to evaluate the chemical composition of ripe Juniperus excelsa M. Bieb. galbuli (female cones) collected from "Izgoraloto Gyune" Reserve in Krichim, Bulgaria. The moisture (36.88%), abs. weight 693.96 g/1000 pcs., and the ash content (10.57%) of ripe galbuli were determined. Lipid fraction (9.12%), cellulose (13.54%), protein (13.64%), and total carbohydrates (31.20%) were evaluated in the ripe galbuli. It was found that the ripe galbuli contained glucose (4.00%) and fructose (4.25%), but disaccharide sucrose was not identified. The main macro elements presented in the sample were K (8390.00 mg/kg), Ca (4596.00 g/kg), Mg (837.72 mg/kg), followed by Na (7.69 mg/kg); while the detected microelements consisted of Zn (8.51 mg/kg), Cu (4.66 mg/kg), Mn (3.65 mg/kg), Fe (3.26 mg/kg), Cr (3.00 mg/kg), Cd (< 0.1 mg/kg), and Pb (0.01 mg/kg).

Keywords: chemical composition, Juniperus excelsa M. Bieb, minerals, ripe galbuli

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Authors: Z. Zaman Asam, M. Ajmal, R. Saeed, H. Miraj, M. Muhammad Ahtisham, B. Hameed, A. -Sattar Nizami

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In Pakistan, environmental degradation and consequent human health deterioration has rapidly accelerated in the past decade due to solid waste mismanagement. As the situation worsens with time, establishment of proper waste management practices is urgently needed especially in semi urban and rural areas of Pakistan. This study uses a concept of Waste Bank, which involves a transfer station for collection of sorted waste fractions and its delivery to the targeted market such as recycling industries, biogas plants, composting facilities etc. The management efficiency and effectiveness of Waste Bank depend strongly on the proficient sorting and collection of solid waste fractions at household level. However, the social attitude towards such a solution in semi urban/rural areas of Pakistan demands certain prerequisites to make it workable. Considering these factors the objectives of this study are to: [A] Obtain reliable data about quantity and characteristics of generated waste to define feasibility of business and design factors, such as required storage area, retention time, transportation frequency of the system etc. [B] Analyze the effects of various social factors on waste generation to foresee future projections. [C] Quantify the improvement in waste sorting efficiency after awareness campaign. We selected Gujrat city of Central Punjab province of Pakistan as it is semi urban adjoined by rural areas. A total of 60 houses (20 from each of the three selected colonies), belonging to different social status were selected. Awareness sessions about waste segregation were given through brochures and individual lectures in each selected household. Sampling of waste, that households had attempted to sort, was then carried out in the three colored bags that were provided as part of the awareness campaign. Finally, refined waste sorting, weighing of various fractions and measurement of dry mass was performed in environmental laboratory using standard methods. It was calculated that sorting efficiency of waste improved from 0 to 52% as a result of the awareness campaign. The generation of waste (dry mass basis) on average from one household was 460 kg/year whereas per capita generation was 68 kg/year. Extrapolating these values for Gujrat Tehsil, the total waste generation per year is calculated to be 101921 tons dry mass (DM). Characteristics found in waste were (i) organic decomposable (29.2%, 29710 tons/year DM), (ii) recyclables (37.0%, 37726 tons/year DM) that included plastic, paper, metal and glass, and (iii) trash (33.8%, 34485 tons/year DM) that mainly comprised of polythene bags, medicine packaging, pampers and wrappers. Waste generation was more in colonies with comparatively higher income and better living standards. In future, data collection for all four seasons and improvements due to expansion of awareness campaign to educational institutes will be quantified. This waste management system can potentially fulfill vital sustainable development goals (e.g. clean water and sanitation), reduce the need to harvest fresh resources from the ecosystem, create business and job opportunities and consequently solve one of the most pressing environmental issues of the country.

Keywords: integrated solid waste management, waste segregation, waste bank, community development

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Authors: Tsige Reda

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Essential oil of Thymus vulgaris was extracted by means of hydro-distillation. This study was done to investigate the chemical composition, antibacterial and antioxidant activities. The chemical composition of the essential oils was determined using gas chromatography coupled to mass spectroscopy (GC-MS). Using disc diffusion assay the antibacterial activity was assessed on one Gram-positive bacteria and one Gram-negative bacteria. The percentage oil yield of the essential oil was found to be 0.97 ± 0.08% (w/w) with yellow color. The physicochemical constants of the oil were also noted. The phytochemical screening of the plant extract revealed the presence of tannins, saponins, phenol, flavonoids, terpenoids, steroids and alkaloids. A total of 18 chemical constituents were identified by Gas Chromatography-Mass Spectroscopy analysis representing 100% of the total essential oil of Thymus vulgaris, with thymol (31.977%), o-cymene (29.992%), and carvacrol (14.541%). Previous studies have revealed that the thymol, o-cymen and carvacrol components of Thymus vulgaris are responsible for their biological activities. Thymus vulgaris have been used traditionally to treat a wide variety of infections. Based on the extensive use and lack of scientific evidence, a study was embarked upon to determine its bioactivity. The essential oil of Thymus vulgaris leaves exhibited higher activity towards the Gram-positive bacteria (Staphylococcus aurous) than the Gram-negative bacteria (Escherichia coli) and also has good antioxidant activity, and can be used medicinal and therapeutic applications. This activity may be due to the high amount of thymol, o-cymen and carvacrol.

Keywords: hydro-distillation, Thymus vulgaris, essential oil composition, phytochemical screening, physicochemical constants, antioxidant activity, antibacterial activity

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Authors: A. O. Adenaiya, S. F. Curling, O. Y. Ogunsanwo, G . A. Ormondroyd

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Treatment of wood with chemicals in order to prolong its service life may prove difficult in some refractory wood species. This impermeability in wood is usually due to biochemical changes which occur during heartwood formation. Bioincision, which is a short-term, controlled microbial decomposition of wood, is one of the promising approaches capable of improving the amenability of refractory wood to chemical treatments. Gmelina Arborea, a mainstay timber species in Nigeria, has impermeable heartwood due to the excessive tyloses which occlude its vessels. Therefore, the chemical uptake and penetration in Gmelina arborea heartwood bioincised with Inonotus dryophilus fungus was investigated. Five mature Gmelina Arborea trees were harvested at the Departmental plantation in Ajibode, Ibadan, Nigeria and a bolt of 300 cm was obtained from the basal portion of each tree. The heartwood portion of the bolts was extracted and converted into dimensions 20 mm x 20 mm x 60 mm and subsequently conditioned (200C at 65% Relative Humidity). Twenty wood samples each were bioincised with the white-rot fungus Inonotus dryophilus (ID, 999) for 3, 5, 7 and 9 weeks using standard procedure, while a set of sterile control samples were prepared. Ten of each bioincised and control sample were pressure-treated with 5% tanalith preservative, while the other ten of each bioincised and control samples were pressure-treated with a liquid dye for easy traceability of the chemical in the wood, both using a full cell treatment process. The bioincised and control samples were evaluated for their Weight Loss before chemical treatment (WL, %), Preservative Absorption (PA, Kg/m3), Preservative Retention (PR, Kg/m3), Axial Absorption (AA, Kg/m3), Lateral Absorption (LA, Kg/m3), Axial Penetration Depth (APD, mm), Radial Penetration Depth (RPD, mm), and Tangential Penetration Depth (TPD, mm). The data obtained were analyzed using ANOVA at α0.05. Results show that the weight loss was least in the samples bioincised for three weeks (0.09%) and highest after 7 weeks of bioincision (0.48%). The samples bioincised for 3 weeks had the least PA (106.72 Kg/m3) and PR (5.87 Kg/m3), while the highest PA (134.9 Kg/m3) and PR were observed after 7 weeks of bioincision (7.42 Kg/m3). The AA ranged from 27.28 Kg/m3 (3 weeks) to 67.05 Kg/m3 (5 weeks), while the LA was least after 5 weeks of incubation (28.1 Kg/m3) and highest after 9 weeks (71.74 Kg/m3). Significantly lower APD was observed in control samples (6.97 mm) than in the samples bioincised after 9weeks (19.22 mm). The RPD increased from 0.08 mm (control samples) to 3.48 mm (5 weeks), while TPD ranged from 0.38 mm (control samples) to 0.63 mm (9 weeks), implying that liquid flow in the wood was predominantly through the axial pathway. Bioincising G. arborea heartwood with I. dryophilus fungus for 9 weeks is capable of enhancing chemical uptake and deeper penetration of chemicals in the wood through the degradation of the occluding vessel tyloses, which is accompanied by a minimal degradation of the polymeric wood constituents.

Keywords: Bioincision, chemical uptake, penetration depth, refractory wood, tyloses

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Authors: N. Ouslimani, M. T. Abadlia

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Environment protection is a precondition for sustained growth and a better quality of life for all people on earth. Aqueous industrial effluents are the main sources of pollution. Among the compounds of these effluents, dyes are particularly resistant to discoloration by conventional methods, and discharges present many problems that must be supported. The scientific literature shows that synthetic organic dyes are compounds used in many industrial sectors. They are found in the chemical, car, paper industry and particularly the textile industry, where all the lines and grades of the chemical family are represented. The affinity between the fibers and dyes vary depending on the chemical structure of dyes and the type of materials to which they are applied. It is not uncommon to find that during the dyeing operation from 15 to 20 % of sulfur dyes, and sometimes up to 40 % of the reactants are discharged with the effluent. This study was conducted for the purpose of fading basics dyes from wastewater using as adsorbent fiber waste material. This technique presents an interesting alternative to usual treatment, as it allows the recovery of waste fibers, which can find uses as raw material for the manufacture of cleaning products or in other sectors In this study the results obtained by fading fiber waste are encouraging, given the rate of color removal which is about 90%.This method also helps to decrease BOD and suspended solids MES in an effective way.

Keywords: adsorption, dyes, fiber, valorization, wastewater

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Authors: Yayan Harry Yadi, L. Meily Kurniawidjaja

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Work activities for MMH (Manual Material Handling) in the storage of liquid catalyst raw material workstations in chemical industries identify high-risk MSDs (Musculoskeletal Disorders). Their work is often performed frequently requires an awkward body posture, twisting, bending because of physical space limited, cold, slippery, and limited tools for transfer container and weighing the liquid chemistry of the catalyst into the container. This study aims to develop an ergonomic work system design on the transfer and weighing process of liquid catalyst raw materials at the storage warehouse. A triangulation method through an interview, observation, and detail study team with assessing the level of risk work posture and complaints. Work postures were analyzed using the RULA method, through the support of CATIA software. The study concludes that ergonomic design can make reduce 3 levels of risk scores awkward posture. CATIA Software simulation provided a comprehensive solution for a better posture of manual material handling at task weigh. An addition of manual material handling tools such as adjustable conveyors, trolley and modification tools semi-mechanical weighing with techniques based on rule ergonomic design can reduce the hazard of chemical fluid spills.

Keywords: ergonomic design, MSDs, CATIA software, RULA, chemical industry

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Authors: Neeraj Kumar Verma

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Lanthanum hydroxide and manganese oxide nanocomposite are synthesized by chemical routes. Physical characterization is done by TEM to look at the size and dispersion of the nanoparticles in the composite. Chemical characterization is done by X-ray diffraction technique and FTIR to ascertain the attachment of the functionalities and bond stretching. Further thermal analysis is done by thermogravimetric analysis to find the tendency of the thermal decomposition in the elevated temperature range of 0-1000°C. Proper analysis and correlation of the various results obtained suggested the controlled growth of crystalline without agglomeration and good stability in the various temperature ranges of the composite.

Keywords: nanoparticles, XRD, TEM, lanthanum hydroxide, manganese oxide

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Authors: Carles Martinez-Almoyna Gual, Jiwon Choi

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Urban communities face risks of disintegration and segregation as a consequence of globalised migration processes towards urban environments. Linking social and cultural components with environmental and economic dimensions becomes the goal of all the disciplines that aim to shape more sustainable urban environments. Solutions require interdisciplinary approaches and the use of a complex array of tools. One of these tools is the implementation of urban farming, which provides a wide range of advantages for creating more inclusive spaces and integrated communities. Since food is strongly related to the values and identities of any cultural group, it can be used as a medium to promote social inclusion in the context of urban multicultural societies. By bringing people together into specific urban sites, food production can be integrated into multifunctional spaces while addressing social, economic and ecological goals. The goal of this research is to assess different approaches to urban agriculture by analysing three existing community gardens located in Newtown, a suburb of Wellington, New Zealand. As a context for developing research, Newtown offers different approaches to urban farming and is really valuable for observing current trends of socialization in diverse and multicultural societies. All three spaces are located on public land owned by Wellington City Council and confined to a small, complex and progressively denser urban area. The developed analysis was focused on social, cultural and physical dimensions, combining community engagement with different techniques of spatial assessment. At the same time, a detailed investigation of each community garden was conducted with comparative analysis methodologies. This multidirectional setting of the analysis was established for extracting from the case studies both specific and typological knowledge. Each site was analysed and categorised under three broad themes: people, space and food. The analysis revealed that all three case studies had really different spatial settings, different approaches to food production and varying profiles of supportive communities. The main differences identified were demographics, values, objectives, internal organization, appropriation, and perception of the space. The community gardens were approached as case studies for developing design research. Following participatory design processes with the different communities, the knowledge gained from the analysis was used for proposing changes in the physical environment. The end goal of the design research was to improve the capacity of the spaces to facilitate social inclusiveness. In order to generate tangible changes, a range of small, strategic and feasible spatial interventions was explored. The smallness of the proposed interventions facilitates implementation by reducing time frames, technical resources, funding needs, and legal processes, working within the community´s own realm. These small interventions are expected to be implemented over time as part of an ongoing collaboration between the different communities, the university, and the local council. The applied research methodology showcases the capacity of universities to develop civic engagement by working with real communities that have concrete needs and face overall threats of disintegration and segregation.

Keywords: community gardening, landscape architecture, participatory design, placemaking, social inclusion

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Authors: M. Saidi, I. Djefour, F. Ait Medjber, A. Melouane, A. Gacem

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The objective of this research is to study the physical and mechanical properties and durability of self-compacting mortars prepared by substituting a part of cement up to a percentage of 30% pozzolan according to different Blaine specific surface area (SSB1=7000 cm²/g and SSB=9000 cm²/g)). Order to evaluate durability, mortars were subjected to chemical attacks in various aggressive environments, a solution of a mixture of nitric acid and ammonium nitrate (HNO₃ + NH₄NO₃) and a magnesium sulfate salt solution (MgSO₄)) with a concentration of 10%, for a period of one month. This study is complemented by a comparative study of the durability of mortars elaborated with sulphate resistant cement (SRC). The results show that these mortars develop long-term, mechanical and chemical resistance better than mortars based Portland cement with 5% gypsum (CEM 1) and SRC. We found that the mass losses are lowest in mortars elaborated with pozzolanic cement (30% substitution with SSB₂) in both of chemical attack solutions (3.28% in the solution acid and 1.16% in the salt solution) and the compressive strength gains of 14.68% and 8.5% respectively in the two media. This is due to the action of pozzolan which fixes portlandite to form hydrated calcium silicate (CSH) from the hydration of tricalcic silicate (C₃S).

Keywords: aggressive environments, durability, mechanical strengths, pozzolanic cement, self-compacting mortar

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Authors: Y. Sunita Rani, Y. Hari Krishna, M. V. Ramana Murthy, K. Sudhaker Reddy

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This article studied effects of radiation and chemical reaction on MHD casson fluoid flow past a Permeable Stretching Sheet in a Porous Medium. Suitable transformations are considered to transform the governing partial differential equations as ordinary ones and then solved by the numerical procedures like Runge- Kutta – Fehlberg shooting technique method. The effects of various governing parameters, on the velocity, temperature and concentration are displayed through graphs and discussed numerically.

Keywords: MHD, Casson fluid, porous medium, permeable stretching sheet

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Authors: Catalina Iticescu, Lucian P. Georgescu, Mihaela Timofti, Gabriel Murariu

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Since the accumulation of large quantities of sewage sludge is producing serious environmental problems, numerous environmental specialists are looking for solutions to solve this problem. The sewage sludge obtained by treatment of municipal wastewater may be used as fertiliser on agricultural soils because such sludge contains large amounts of nitrogen, phosphorus and organic matter. In many countries, sewage sludge is used instead of chemical fertilizers in agriculture, this being the most feasible method to reduce the increasingly larger quantities of sludge. The use of sewage sludge on agricultural soils is allowed only with a strict monitoring of their physical and chemical parameters, because heavy metals exist in varying amounts in sewage sludge. Exceeding maximum permitted quantities of harmful substances may lead to pollution of agricultural soil and may cause their removal aside because the plants may take up the heavy metals existing in soil and these metals will most probably be found in humans and animals through food. The sewage sludge analyzed for the present paper was extracted from the Wastewater Treatment Station (WWTP) Galati, Romania. The physico-chemical parameters determined were: pH (upH), total organic carbon (TOC) (mg L⁻¹), N-total (mg L⁻¹), P-total (mg L⁻¹), N-NH₄ (mg L⁻¹), N-NO₂ (mg L⁻¹), N-NO₃ (mg L⁻¹), Fe-total (mg L⁻¹), Cr-total (mg L⁻¹), Cu (mg L⁻¹), Zn (mg L⁻¹), Cd (mg L⁻¹), Pb (mg L⁻¹), Ni (mg L⁻¹). The determination methods were electrometrical (pH, C, TSD) - with a portable HI 9828 HANNA electrodes committed multiparameter and spectrophotometric - with a Spectroquant NOVA 60 - Merck spectrophotometer and with specific Merck parameter kits. The tests made pointed out the fact that the sludge analysed is low heavy metal falling within the legal limits, the quantities of metals measured being much lower than the maximum allowed. The results of the tests made to determine the content of nutrients in the sewage sludge have shown that the existing nutrients may be used to increase the fertility of agricultural soils. Other tests were carried out on lands where sewage sludge was applied in order to establish the maximum quantity of sludge that may be used so as not to constitute a source of pollution. The tests were made on three plots: a first batch with no mud and no chemical fertilizers applied, a second batch on which only sewage sludge was applied, and a third batch on which small amounts of chemical fertilizers were applied in addition to sewage sludge. The results showed that the production increases when the soil is treated with sludge and small amounts of chemical fertilizers. Based on the results of the present research, a fertilization plan has been suggested. This plan should be reconsidered each year based on the crops planned, the yields proposed, the agrochemical indications, the sludge analysis, etc.

Keywords: agricultural use, crops, physico–chemical parameters, sewage sludge

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Authors: Doufoungognon C. Kone

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Global change, in particular pollution and global warming, threatens ecosystems and the biodiversity they harbor. Due to pollutants exposure, organisms might modify their thermal niches in order to track the thermal conditions limiting the negative impacts of chemical stressors depending on their mode of action. This study tests the influence of different pollutants, copper, salt, and chloramphenicol, on the thermal preferences of the ciliate Tetrahymena thermophila. Six genotypes were exposed to a gradient of concentrations ranging from 0 to 500mg/L for copper, 0 to 300 mg/l for chloramphenicol, and 0 to 12g/l for salt in synthetic media at eight temperatures ranging from 11 to 39° C. The measured fitness proxies are the maximum growth rate and the 50% growth inhibitory concentration (IC50). The results show that the majority of genotypes are more resistant to chloramphenicol in temperatures below their thermal optimum without pollutants, while they better tolerate other salt and copper in temperatures above their thermal optimum. In addition, generalists reduce their niche width while specialists widen it in chloramphenicol. Overall, results suggest that global warming would have a particularly deleterious effect in the case of chemical pollution. This pollution would induce the full disruption of the thermal habitats.

Keywords: ciliate, thermal niche, growth rate, toxicity, multiple stressors

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Authors: Rabia Waseem, Low Kah Hin, Najihah Mohamed Hashim

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The variability in the chemical components of the Syzygium species essential oils has been evaluated. The leaves of Syzygium species have been collected from Perak, Malaysia. The essential oils extracted by using the conventional Hydro-distillation extraction procedure and analyzed by using Gas chromatography System attached with Mass Spectrometry (GCMS). Twenty-seven constituents were found in Syzygium species in which the major constituents include: α-Pinene (3.94%), α-Thujene (2.16%), α-Terpineol (2.95%), g-Elemene (2.89%) and D-Limonene (14.59%). The aim of this study was the comparison between the evaluated data and existing literature to fortify the major variability through statistical analysis.

Keywords: chemotaxonomy, cluster analysis, essential oil, medicinal plants, statistical analysis

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Authors: Gondrexon, Gonon, Mendil-Jakani, Mareau

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Proton Exchange Membrane Fuel Cells (PEMFCs) seems to be a promising device used for converting hydrogen into electricity. PEMFC is made of a Membrane Electrode Assembly (MEA) composed of a Proton Exchange Membrane (PEM) sandwiched by two catalytic layers. Nowadays, specific performances are targeted in order to ensure the long-term expansion of this technology. Current polymers used (perfluorinated as Nafion®) are unsuitable (loss of mechanical properties) for the high-temperature range. To overcome this issue, sulfonated polyaromatic polymers appear to be a good alternative since it has very good thermomechanical properties. However, their proton conductivity and chemical stability (oxidative resistance to H2O2 formed during fuel cell (FC) operating) are very low. In our team, we patented an original concept of hybrid membranes able to fulfill the specific requirements for PEMFC. This idea is based on the improvement of commercialized polymer membrane via an easy and processable stabilization thanks to sol-gel (SG) chemistry with judicious embeded chemical functions. This strategy is thus breaking up with traditional approaches (design of new copolymers, use of inorganic charges/additives). In 2020, we presented the elaboration and functional properties of a 1st generation of hybrid membranes with promising performances and durability. The latter was made by self-condensing a SG phase with 3(mercaptopropyl)trimethoxysilane (MPTMS) inside a commercial sPEEK host membrane. The successful in-situ condensation reactions of the MPTMS was demonstrated by measures of mass uptakes, FTIR spectroscopy (presence of C-Haliphatics) and solid state NMR 29Si (T2 & T3 signals of self-condensation products). The ability of the SG phase to prevent the oxidative degradation of the sPEEK phase (thanks to thiol chemical functions) was then proved with H2O2 accelerating tests and FC operating tests. A 2nd generation made of thiourea functionalized SG precursors (named HTU & TTU) was made after. By analysing in depth the morphologies of these different hybrids by direct space analysis (AFM/SEM/TEM) and reciprocal space analysis (SANS/SAXS/WAXS), we highlighted that both SG phase morphology and its localisation into the host has a huge impact on the PEM functional properties observed. This relationship is also dependent on the chemical function embedded. The hybrids obtained have shown very good chemical resistance during aging test (exposed to H2O2) compared to the commercial sPEEK. But the chemical function used is considered as “sacrificial” and cannot react indefinitely with H2O2. Thus, we are now working on a 3rd generation made of both sacrificial/regenerative chemical functions which are expected to inhibit the chemical aging of sPEEK more efficiently. With this work, we are confident to reach a predictive approach of the key parameters governing the final properties.

Keywords: fuel cells, ionomers, membranes, sPEEK, chemical stability

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Authors: Fabienne Baraud, Lydia Leleyter, Sandra Poree, Melanie Lemoine

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SEDIBRIC (valorization de SEDIments en BRIQues et tuiles) is a French project that aims to replace a part of natural clays with dredged sediments in the preparation of fired bricks in order to propose an alternative solution for the management of harbor dredged sediments. The feasibility of such re-use is explored from a technical, economic, and environmental point of view. The present study focuses on the potential environmental impact of various chemical elements (Al, Ca, Cd, Co, Cr, Cu, Fe, Ni, Mg, Mn, Pb, Ti, and Zn) that are initially present in the dredged sediments. The total content (after acid digestion) and the environmental availability (estimated by single extractions with various extractants) of these elements are determined in the raw sediments and in the obtained fired bricks. The possible influence of some steps of the manufacturing process (sediment pre-treatment, firing) is also explored. The first results show that the pre-treatment step, which uses tap water to desalinate the raw sediment, does not influence the environmental availability of the studied elements. However, the firing process, performed at 900°C, can affect the amount of some elements detected in the bricks, as well as their environmental availability. We note that for Cr, or Ni, the HCl or EDTA availability was increased in the brick (compared to the availability in the raw sediment). For Cd, Cu, Pb, and Zn, the HCl and EDTA availability was reduced in the bricks, meaning that these elements were stabilized within the bricks.

Keywords: bricks, chemical extraction, metals, sediment

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Authors: Pei Li, Chunyi Zhi

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Conversion-type lithium-ion batteries show great potential as high-energy-density, low-cost and sustainable alternatives to current transition-metal-based intercalation cells. Li-Cl₂/Li⁻I₂ conversion batteries, based on anionic redox reactions of Cl⁻/Cl⁰ or I⁻/I⁰, are highly attractive due to their superior voltage and capacity. However, a redox-active and reversible chlorine cathode has not been developed in organic electrolytes. And thermodynamic instability and shuttling issues of iodine cathodes have plagued the active iodine loading, capacity retention and cyclability. By reversible chemical bonds, we develop reversible chlorine redox reactions in organic electrolytes with interhalogen bonds between I and Cl for Li-I₂ batteries and develop a highly thermally stable I/I₃--bonded organic salts with iodine content up to 80% as cathode materials for the rechargeable Li-I₂ batteries. The demonstration of reversible chemical bonds enabled rechargeable Li-halogen batteries opens a new avenue to develop halogen compound cathodes.

Keywords: conversion-type, chlorine, halogen cathode, high energy density, iodine, interhalogen bond, lithium-ion batteries

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Authors: Jie Li, Nick Manning

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The mass rural-urban migrants in China associated with the urbanization processes bear significant implications on public health, which is an important yet under-researched area. Urban social and built environment, such as noise, air pollution, high population density, and social segregation, has the potential to contribute to mental illness. In China, rural-urban migrants are also faced with institutional discrimination tied to the hukou (household registration) system, through which they are denied of full citizenship to basic social welfare and services, which may elevate the stress of urban living and exacerbate the risks to mental illness. This paper aims to link the sociospatial exclusion, everyday life experiences and its mental health consequences on rural to urban migrants living in the mega-city of Shanghai. More specifically, it asks what the daily experience of being a migrant in Shanghai is actually like, particularly regarding sources of stress from housing, displacement, service accessibility, and cultural conflict, and whether these stresses affect mental health? Secondary data from literature review on migration, urban studies, and epidemiology research, as well as primary data from preliminary field trip observations and interviews are used in the analysis.

Keywords: migration, urbanisation, mental health, China

Procedia PDF Downloads 375

Authors: Tuji Jemal Ahmed

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Fresh produce is an essential component of a healthy diet. However, it can also be a potential source of pathogenic microorganisms that can cause foodborne illnesses. Traditional disinfection methods, such as washing with water and chlorine, have limitations and may not effectively remove or inactivate all microorganisms. This has led to the development of alternative/new methods of fresh produce disinfection, including physical and chemical methods. In this paper, we explore the physical and chemical new methods of fresh produce disinfection, their advantages and disadvantages, and their suitability for different types of produce. Physical methods of disinfection, such as ultraviolet (UV) radiation and high-pressure processing (HPP), are crucial in ensuring the microbiological safety of fresh produce. UV radiation uses short-wavelength UV-C light to damage the DNA and RNA of microorganisms, and HPP applies high levels of pressure to fresh produce to reduce the microbial load. These physical methods are highly effective in killing a wide range of microorganisms, including bacteria, viruses, and fungi. However, they may not penetrate deep enough into the product to kill all microorganisms and can alter the sensory characteristics of the product. Chemical methods of disinfection, such as acidic electrolyzed water (AEW), ozone, and peroxyacetic acid (PAA), are also important in ensuring the microbiological safety of fresh produce. AEW uses a low concentration of hypochlorous acid and a high concentration of hydrogen ions to inactivate microorganisms, ozone uses ozone gas to damage the cell membranes and DNA of microorganisms, and PAA uses a combination of hydrogen peroxide and acetic acid to inactivate microorganisms. These chemical methods are highly effective in killing a wide range of microorganisms, but they may cause discoloration or changes in the texture and flavor of some products and may require specialized equipment and trained personnel to produce and apply. In conclusion, the selection of the most suitable method of fresh produce disinfection should take into consideration the type of product, the level of microbial contamination, the effectiveness of the method in reducing the microbial load, and any potential negative impacts on the sensory characteristics, nutritional composition, and safety of the produce.

Keywords: fresh produce, pathogenic microorganisms, foodborne illnesses, disinfection methods

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Authors: F. Laatar, S. Ktifa, H. Ezzaouia

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Plasma Enhanced Chemical Vapor Deposition (PECVD) method is used to deposit hydrogenated nanocrystalline silicon films (nc-Si: H) on Porous Anodic Alumina Films (PAF) on glass substrate at different deposition duration. Influence of the deposition time on the physical properties of nc-Si: H grown on PAF was investigated through an extensive correlation between micro-structural and optical properties of these films. In this paper, we present an extensive study of the morphological, structural and optical properties of these films by Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD) techniques and a UV-Vis-NIR spectrometer. It was found that the changes in DT can modify the films thickness, the surface roughness and eventually improve the optical properties of the composite. Optical properties (optical thicknesses, refractive indexes (n), absorption coefficients (α), extinction coefficients (k), and the values of the optical transitions EG) of this kind of samples were obtained using the data of the transmittance T and reflectance R spectra’s recorded by the UV–Vis–NIR spectrometer. We used Cauchy and Wemple–DiDomenico models for the analysis of the dispersion of the refractive index and the determination of the optical properties of these films.

Keywords: hydragenated nanocrystalline silicon, plasma processing chemical vapor deposition, X-ray diffraction, optical properties

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Authors: P. Zakikhani, R. Zahari, M. T. H. Sultan, D. L. Majid

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Natural plant fibres reinforced polymeric composite materials have been used in many fields of our lives to save the environment. Especially, bamboo fibres due to its environmental sustainability, mechanical properties, and recyclability have been utilized as reinforced polymer matrix composite in construction industries. In this review study bamboo structure and three different methods such as mechanical, chemical and combination of mechanical and chemical to extract fibres from bamboo are summarized. Each extraction method has been done base on the application of bamboo. In addition Bamboo fibre is compared with glass fibre from various aspects and in some parts it has advantages over the glass fibre.

Keywords: bamboo fibres, natural fibres, bio composite, mechanical extraction, glass fibres

Procedia PDF Downloads 491

Authors: A. A. Abaker Omer, H. B. Mohamed Balh, W. Liu, A. Abas, J. Yu, S. Li, W. Ma, W. El Kolaly, Y. Y. Ahmed Abuker

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We have discovered an important technical solution that could make new approaches in the processing of wet silicon etching, especially in the production of photovoltaic cells. During its inferior light-trapping and structural properties, the inverted pyramid structure outperforms the conventional pyramid textures and black silicone. The traditional pyramid textures and black silicon can only be accomplished with more advanced lithography, laser processing, etc. Importantly, our data demonstrate the feasibility of an inverted pyramidal structure of silicon via one-step Cu-catalyzed chemical etching (CCCE) in Cu (NO₃)₂/HF/H₂O₂/H₂O solutions. The effects of etching time and reaction temperature on surface geometry and light trapping were systematically investigated. The conclusion shows that the inverted pyramid structure has ultra-low reflectivity of ~4.2% in the wavelength of 300~1000 nm; introduce of Cu particles can significantly accelerate the dissolution of the silicon wafer. The etching and the inverted pyramid structure formation mechanism are discussed. Inverted pyramid structure with outstanding anti-reflectivity includes useful applications throughout the manufacture of semi-conductive industry-compatible solar cells, and can have significant impacts on industry colleagues and populations.

Keywords: Cu-catalyzed chemical etching, inverted pyramid nanostructured, reflection, solar cells

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Authors: G. Singh, H.Schuster, U. Füssel

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The stability of electric arc and durability of electrode tip used in Tungsten Inert Gas (TIG) welding demand a metallurgical study about the chemical transport mechanism of emitter oxide particles in tungsten electrode during its real welding conditions. The tungsten electrodes doped with emitter oxides of rare earth oxides such as La₂O₃, Th₂O₃, Y₂O₃, CeO₂ and ZrO₂ feature a comparatively lower work function than tungsten and thus have superior emission characteristics due to lesser surface temperature of the cathode. The local change in concentration of these emitter particles in tungsten electrode due to high temperature diffusion (chemical transport) can change its functional properties like electrode temperature, work function, electron emission, and stability of the electrode tip shape. The resulting increment in tip surface temperature results in the electrode material loss. It was also observed that the tungsten recrystallizes to large grains at high temperature. When the shape of grain boundaries are granular in shape, the intergranular diffusion of oxide emitter particles takes more time to reach the electrode surface. In the experimental work, the microstructure of the used electrode's tip surface will be studied by scanning electron microscope and reflective X-ray technique in order to gauge the extent of the diffusion and chemical reaction of emitter particles. Besides, a simulated model is proposed to explain the effect of oxide particles diffusion on the electrode’s microstructure, electron emission characteristics, and electrode tip erosion. This model suggests metallurgical modifications in tungsten electrode to enhance its erosion resistance.

Keywords: rare-earth emitter particles, temperature-dependent diffusion, TIG welding, Tungsten electrode

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Authors: Zineb Ouahdi

Abstract:

Spirocyclic compound derivatives, with their unique heterocyclic motifs, serve as a continual source of inspiration in the pursuit of developing potential therapeutic agents. These compounds are diverse in their chemical structures; some have fully saturated skeletons, while others are partially unsaturated. Nevertheless, these compounds share a characteristic feature with natural products - the presence of at least one heteroatom in one of their rings. The inclusion of a C = O dipolarophile in pyridazinones imparts an exciting aspect for 1,3-dipolar cycloaddition reactions, the focal point of our study. Our research has involved a detailed theoretical investigation of the reaction between ethyl (Z)-2-bromo-2-(2-(p-tolyl)hydrazono)acetate and 6-methyl-4,5-dihydropyridazine-3(2H)-one. This has been accomplished using the DFT/B3LYP/6-31g(d,p) method, intending to illuminate the chemical pathway of this reaction. The chemical reactivity theories we used for this purpose included FMO, TS, and local and global indices derived from conceptual DFT. The theoretical framework outlined in this study allowed us to propose a reaction mechanism for cycloaddition reactions. It also enabled the identification of the potential activities of the analyzed compounds (P1, P2, P3, P4, P5, and P6) against the major protease of the coronavirus disease (COVID-19). This was achieved using various computational tools, including AutoDock Tools, Autodock Vina, Autodock 4, and PYRX.

Keywords: MEDT, pyridazin, cycloaddition, FMO, DFT, docking

Procedia PDF Downloads 103