Search results for: structure and morphology
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 8663

Search results for: structure and morphology

5603 Hybrid Capture Resolves the Phylogeny of the Pantropically Distributed Zanthoxylum (Rutaceae) and Reveals an Old World Origin

Authors: Lee Ping Ang, Salvatore Tomasello, Jun Wen, Marc S. Appelhans

Abstract:

With about 225 species, Zanthoxylum L. is the second most species rich genus in Rutaceae. It is the only genus with a pantropical distribution. Economically, it is used in several Asian countries as traditional medicine and spice. In the past Zanthoxylum was divided into two genera, the temperate Zanthoxylum sensu strictu (s.s.) and the (sub)tropical Fagara, due to the large differences in flower morphology: heterochlamydeous in Fagara and homochlamydeous in Zanthoxylum s.s.. This genus is much under studied and previous phylogenetic studies using Sanger sequencing did not resolve the relationships sufficiently. In this study, we use Hybrid Capture with a specially designed bait set for Zanthoxylum to sequence 347 putatively single-copy genes. The taxon sampling has been largely improved as compared to previous studies and the preliminary results will be based on 371 specimens representing 133 species from all continents and major island groups. Our preliminary results reveal similar tree topology as the previous studies while providing more details to the backbone of the phylogeny. The phylogenetic tree consists of four main clades: A) African/Malagasy clade, B) Z. asiaticum clade - a clade consisting widespread species occurring in (sub)tropical Asia and Africa as well as Madagascar, C) Asian/Pacific clade and D) American clade, which also includes the temperate Asian species. The merging of Fagara and Zanthoxylum is supported by our results and the homochlamydeous flowers of Zanthoxylum s.s. are likely derived from heterochlamydeous flowers. Several of the morphologically defined sections within Zanthoxylum are not monophyletic. The study dissemination will (1) introduce the framework of this project; (2) present preliminary results and (3) the ongoing progress of the study.

Keywords: Zanthoxylum, phylogenomic, hybrid capture, pantropical

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5602 Structural, Vibrational, Magnetic, and Electronic Properties of La₂MMnO₆ Double Perovskites with M = Ni, Co, and Zn

Authors: Hamza Ouachtouk, Amine Harbi, Said Azerblou, Youssef Naimi, El Mostafa Tace

Abstract:

This study delves into the structural, vibrational, magnetic, and electronic properties of La₂MMnO₆ double perovskites, where M denotes Ni, Co, and Zn. Recognized for their versatile ionic configurations within the A and B sub-lattices, double perovskite oxides have attracted considerable interest due to their extensive array of physical properties, which include multiferroic behavior, colossal magnetoresistance, and ferroelectric/piezoelectric functionalities. These materials are pivotal for energy-related technologies like solid oxide fuel cells and water-splitting catalysis, attributed to their superior oxygen ion transport and storage capabilities. This research places particular emphasis on La₂NiMnO₆ and La₂CoMnO₆, known for their distinct magnetic, electric, and multiferroic properties, and extends the investigation to La₂ZnMnO₆, synthesized via high-temperature solid-state chemistry. This addition aims to ascertain the impact of zinc substitution on these properties. Structural analysis through X-ray diffraction has confirmed a monoclinic structure within the P2₁/n space group. Comprehensive vibrational studies utilizing infrared and Raman spectroscopy, alongside additional XRD assessments, provide a detailed examination of the dynamic and electronic behaviors of these compounds. The results underscore the significant role of chemical composition in modulating their functional properties. Comparatively, this study highlights that zinc substitution notably alters the electronic and magnetic responses, which could enhance the applicability of these materials in advanced energy technologies. This expanded analysis not only reinforces our understanding of La₂MMnO₆'s physical characteristics but also highlights its potential applications in the next generation of energy solutions.

Keywords: double perovskites, structural analysis, vibrational spectroscopy, magnetic properties, electronic properties, high-temperature solid-state chemistry, La₂MMnO₆, monoclinic structure, x-ray diffraction

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5601 Interpretable Deep Learning Models for Medical Condition Identification

Authors: Dongping Fang, Lian Duan, Xiaojing Yuan, Mike Xu, Allyn Klunder, Kevin Tan, Suiting Cao, Yeqing Ji

Abstract:

Accurate prediction of a medical condition with straight clinical evidence is a long-sought topic in the medical management and health insurance field. Although great progress has been made with machine learning algorithms, the medical community is still, to a certain degree, suspicious about the model's accuracy and interpretability. This paper presents an innovative hierarchical attention deep learning model to achieve good prediction and clear interpretability that can be easily understood by medical professionals. This deep learning model uses a hierarchical attention structure that matches naturally with the medical history data structure and reflects the member’s encounter (date of service) sequence. The model attention structure consists of 3 levels: (1) attention on the medical code types (diagnosis codes, procedure codes, lab test results, and prescription drugs), (2) attention on the sequential medical encounters within a type, (3) attention on the medical codes within an encounter and type. This model is applied to predict the occurrence of stage 3 chronic kidney disease (CKD3), using three years’ medical history of Medicare Advantage (MA) members from a top health insurance company. The model takes members’ medical events, both claims and electronic medical record (EMR) data, as input, makes a prediction of CKD3 and calculates the contribution from individual events to the predicted outcome. The model outcome can be easily explained with the clinical evidence identified by the model algorithm. Here are examples: Member A had 36 medical encounters in the past three years: multiple office visits, lab tests and medications. The model predicts member A has a high risk of CKD3 with the following well-contributed clinical events - multiple high ‘Creatinine in Serum or Plasma’ tests and multiple low kidneys functioning ‘Glomerular filtration rate’ tests. Among the abnormal lab tests, more recent results contributed more to the prediction. The model also indicates regular office visits, no abnormal findings of medical examinations, and taking proper medications decreased the CKD3 risk. Member B had 104 medical encounters in the past 3 years and was predicted to have a low risk of CKD3, because the model didn’t identify diagnoses, procedures, or medications related to kidney disease, and many lab test results, including ‘Glomerular filtration rate’ were within the normal range. The model accurately predicts members A and B and provides interpretable clinical evidence that is validated by clinicians. Without extra effort, the interpretation is generated directly from the model and presented together with the occurrence date. Our model uses the medical data in its most raw format without any further data aggregation, transformation, or mapping. This greatly simplifies the data preparation process, mitigates the chance for error and eliminates post-modeling work needed for traditional model explanation. To our knowledge, this is the first paper on an interpretable deep-learning model using a 3-level attention structure, sourcing both EMR and claim data, including all 4 types of medical data, on the entire Medicare population of a big insurance company, and more importantly, directly generating model interpretation to support user decision. In the future, we plan to enrich the model input by adding patients’ demographics and information from free-texted physician notes.

Keywords: deep learning, interpretability, attention, big data, medical conditions

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5600 Modified Silicates as Dissolved Oxygen Sensors in Water: Structural and Optical Properties

Authors: Andile Mkhohlakali, Tien-Chien Jen, James Tshilongo, Happy Mabowa

Abstract:

Among different parameters, oxygen is one of the most important analytes of interest, dissolved oxygen (DO) concentration is very crucial and significant for various areas of physical, chemical, and environmental monitoring. Herein we report oxygen-sensitive luminophores -based lanthanum(III) trifluoromethanesulfonate), [La]³⁺ was encapsulated into SiO₂-based xerogel matrix. The nanosensor is composed of organically modified silica nanoparticles, doped with the luminescent oxygen–sensitive lanthanum(III) trifluoromethanesulfonate complex. The precursor materials used for sensing film were triethyl ethoxy silane (TEOS) and (3-Mercaptopropyltriethoxysilane) (MPTMS- TEOS) used for SiO2-baed matrices. Brunauer–Emmett–Teller (BET), and BJH indicate that the SiO₂ transformed from microporous to mesoporous upon the addition of La³⁺ luminophore with increased surface area (SBET). The typical amorphous SiO₂ based xerogels were revealed with X-Ray diffraction (XRD) and Selected Area Electron Diffraction (SAED) analysis. Scanning electron microscope- (SEM) and transmission electron microscope (TEM) showed the porous morphology and reduced particle for SiO₂ and La-SiO₂ xerogels respectively. The existence of elements, siloxane networks, and thermal stability of xerogel was confirmed by energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), and Thermographic analysis (TGA). UV-Vis spectroscopy and photoluminescence (PL) have been used to characterize the optical properties of xerogels. La-SiO₂ demonstrates promising characteristic features of an active sensing film for dissolved oxygen in the water. Keywords: Sol-gel, ORMOSILs, encapsulation, Luminophores quenching, O₂-sensing

Keywords: sol-gel, ORMOSILs, luminophores quenching, O₂-sensing

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5599 Assessment of the Impact of Family Care Team in the District Health System of Regional Health, Thailand

Authors: Nithra Kitreerawutiwong, Sunsanee Mekrungrongwong, Artitaya Wongwonsin, Chakkraphan Phetphoom, Buaploy Phromjang

Abstract:

Background: Thailand has implemented a district health system based on the concept of primary health care. Since 2014, Family Care Team (FCT) was launched to improve the quality of care through a multidisciplinary team include not only the health sector but also social sector work together. FCT classified into 3 levels: district, sub-district, and community. This system now consists of 66,353 teams, including 3,890 teams at district level, 12,237 teams at the sub-district level, and 50,326 teams at the community level. There is a report regarding assessment the situation and perception on FCT, however, relatively few examined the operationality of this policy. This study aimed to explore the perception of district manager on the process of the implementation of FCT policy and the factors associating to implement FCT in the district health system. Methods/Results: Forty in-depth interviews were performed: 5 of primary care manager at the provincial medical health office, 5 of community hospital director, 5 of district administrative health office, 10 of sub-district health promoting hospital, and 10 of local organization. Semi-structure interview guidelines were used in the discussions. The data was analyzed by thematic analysis. This policy was formulated based on the demographic change and epidemiology transition to serve a long term care for elderly. Facilitator factors are social capital in district health systems such as family health leader and multidisciplinary team. Barrier factors are communication to the frontline provider and local organization. The output of this policy in relation to the structure of FCT is well-defined. Unanticipated effects include training of FCT in community level. Conclusion: Early feedback from healthcare manager is valuable information for the improvement of FCT to function optimally. Moreover, in the long term, health outcome need to be evaluated.

Keywords: family care team, district health system, primary care, qualitative study

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5598 Use of Geometrical Relationship in the Ancient Vihara Housing Reclining Buddha Remains of Thailand's Kamphaeng Phet World Heritage Site

Authors: Vacharee Svamivastu

Abstract:

This research investigates the application of geometrical relationship to the ancient religious assembly hall (Vihara) housing a reclining Buddha statue of Thailand's Kamphaeng Phet Historical Park. The study utilizes the archaeological and wooden roof structure remains of the Vihara as the prima facie evidence, supplemented with evidence from other active archaeological sites with architectural kinship as well as Buddhist ideology. At present, the wooden roofs of the Vihara fell prey to the elements and there remain only the base, columns and enclosing walls. Unlike typical Viharas whose floor plan are of rectangular shape, the floor plan of the Vihara housing the reclining Buddha is of square configuration of 25x25m. Further observation has revealed the utilization of large laterite boulders as the principal construction material of the assembly hall (Vihara) columns. The laterite columns are of square shape (1x1m) and various heights (H), ranging from 3.50m to 5.50m. The erection of the Vihara required a total of 36 laterite columns. The pattern of columns arrangement is of two rows of inner columns, two rows of outer columns and two rows of verandah columns. The space between pairs of the verandah columns was stacked with laterite blocks of varying sizes to form the Vihara walls with small openings for ventilation. Upon applying the geometrical relationship-grid system to the Vihara, the results reveal that the placement of the columns was deliberately and masterfully undertaken such that the center of the square-shaped Vihara is conspicuously spacious so as to accommodate the sacred reclining Buddha statue. The elegance of the Vihara demonstrates the ingenious application of geometrical relationship to transforming a space into a structure (i.e. Vihara) of architectural and religious significance.

Keywords: geometrical relationship, the religious assembly hall, Vihara, Kamphaeng Phet School of Master Builder

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5597 The Contribution of Corpora to the Investigation of Cross-Linguistic Equivalence in Phraseology: A Contrastive Analysis of Russian and Italian Idioms

Authors: Federica Floridi

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The long tradition of contrastive idiom research has essentially been focusing on three domains: the comparison of structural types of idioms (e.g. verbal idioms, idioms with noun-phrase structure, etc.), the description of idioms belonging to the same thematic groups (Sachgruppen), the identification of different types of cross-linguistic equivalents (i.e. full equivalents, partial equivalents, phraseological parallels, non-equivalents). The diastratic, diachronic and diatopic aspects of the compared idioms, as well as their syntactic, pragmatic and semantic properties, have been rather ignored. Corpora (both monolingual and parallel) give the opportunity to investigate the actual use of correlating idioms in authentic texts of L1 and L2. Adopting the corpus-based approach, it is possible to draw attention to the frequency of occurrence of idioms, their syntactic embedding, their potential syntactic transformations (e.g., nominalization, passivization, relativization, etc.), their combinatorial possibilities, the variations of their lexical structure, their connotations in terms of stylistic markedness or register. This paper aims to present the results of a contrastive analysis of Russian and Italian idioms referring to the concepts of ‘beginning’ and ‘end’, that has been carried out by using the Russian National Corpus and the ‘La Repubblica’ corpus. Beyond the digital corpora, bilingual dictionaries, like Skvorcova - Majzel’, Dobrovol’skaja, Kovalev, Čerdanceva, as well as monolingual resources, have been consulted. The study has shown that many of the idioms that have been traditionally indicated as cross-linguistic equivalents on bilingual dictionaries cannot be considered correspondents. The findings demonstrate that even those idioms, that are formally identical in Russian and Italian and are presumably derived from the same source (e.g., conceptual metaphor, Bible, classical mythology, World literature), exhibit differences regarding usage. The ultimate purpose of this article is to highlight that it is necessary to review and improve the existing bilingual dictionaries considering the empirical data collected in corpora. The materials gathered in this research can contribute to this sense.

Keywords: corpora, cross-linguistic equivalence, idioms, Italian, Russian

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5596 Concrete Mixes for Sustainability

Authors: Kristyna Hrabova, Sabina Hüblova, Tomas Vymazal

Abstract:

Structural design of concrete structure has the result in qualities of structural safety and serviceability, together with durability, robustness, sustainability and resilience. A sustainable approach is at the heart of the research agenda around the world, and the Fibrillation Commission is also working on a new model code 2020. Now it is clear that the effects of mechanical, environmental load and even social coherence need to be reflected and included in the designing and evaluating structures. This study aimed to present the methodology for the sustainability assessment of various concrete mixtures.

Keywords: concrete, cement, sustainability, Model Code 2020

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5595 Personnel Selection Based on Step-Wise Weight Assessment Ratio Analysis and Multi-Objective Optimization on the Basis of Ratio Analysis Methods

Authors: Emre Ipekci Cetin, Ebru Tarcan Icigen

Abstract:

Personnel selection process is considered as one of the most important and most difficult issues in human resources management. At the stage of personnel selection, the applicants are handled according to certain criteria, the candidates are dealt with, and efforts are made to select the most appropriate candidate. However, this process can be more complicated in terms of the managers who will carry out the staff selection process. Candidates should be evaluated according to different criteria such as work experience, education, foreign language level etc. It is crucial that a rational selection process is carried out by considering all the criteria in an integrated structure. In this study, the problem of choosing the front office manager of a 5 star accommodation enterprise operating in Antalya is addressed by using multi-criteria decision-making methods. In this context, SWARA (Step-wise weight assessment ratio analysis) and MOORA (Multi-Objective Optimization on the basis of ratio analysis) methods, which have relatively few applications when compared with other methods, have been used together. Firstly SWARA method was used to calculate the weights of the criteria and subcriteria that were determined by the business. After the weights of the criteria were obtained, the MOORA method was used to rank the candidates using the ratio system and the reference point approach. Recruitment processes differ from sector to sector, from operation to operation. There are a number of criteria that must be taken into consideration by businesses in accordance with the structure of each sector. It is of utmost importance that all candidates are evaluated objectively in the framework of these criteria, after these criteria have been carefully selected in the selection of suitable candidates for employment. In the study, staff selection process was handled by using SWARA and MOORA methods together.

Keywords: accommodation establishments, human resource management, multi-objective optimization on the basis of ratio analysis, multi-criteria decision making, step-wise weight assessment ratio analysis

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5594 The Structural Alteration of DNA Native Structure of Staphylococcus aureus Bacteria by Designed Quinoxaline Small Molecules Result in Their Antibacterial Properties

Authors: Jeet Chakraborty, Sanjay Dutta

Abstract:

Antibiotic resistance by bacteria has proved to be a severe threat to mankind in recent times, and this fortifies an urgency to design and develop potent antibacterial small molecules/compounds with nonconventional mechanisms than the conventional ones. DNA carries the genetic signature of any organism, and bacteria maintain their genomic DNA inside the cell in a well-regulated compact form with the help of various nucleoid associated proteins like HU, HNS, etc. These proteins control various fundamental processes like gene expression, replication, etc., inside the cell. Alteration of the native DNA structure of bacteria can lead to severe consequences in cellular processes inside the bacterial cell that ultimately result in the death of the organism. The change in the global DNA structure by small molecules initiates a plethora of cellular responses that have not been very well investigated. Echinomycin and Triostin-A are biologically active Quinoxaline small molecules that typically consist of a quinoxaline chromophore attached with an octadepsipeptide ring. They bind to double-stranded DNA in a sequence-specific way and have high activity against a wide variety of bacteria, mainly against Gram-positive ones. To date, few synthetic quinoxaline scaffolds were synthesized, displaying antibacterial potential against a broad scale of pathogenic bacteria. QNOs (Quinoxaline N-oxides) are known to target DNA and instigate reactive oxygen species (ROS) production in bacteria, thereby exhibiting antibacterial properties. The divergent role of Quinoxaline small molecules in medicinal research qualifies them for the evaluation of their antimicrobial properties as a potential candidate. The previous study from our lab has given new insights on a 6-nitroquinoxaline derivative 1d as an intercalator of DNA, which induces conformational changes in DNA upon binding.7 The binding event observed was dependent on the presence of a crucial benzyl substituent on the quinoxaline moiety. This was associated with a large induced CD (ICD) appearing in a sigmoidal pattern upon the interaction of 1d with dsDNA. The induction of DNA superstructures by 1d at high Drug:DNA ratios was observed that ultimately led to DNA condensation. Eviction of invitro-assembled nucleosome upon treatment with a high dose of 1d was also observed. In this work, monoquinoxaline derivatives of 1d were synthesized by various modifications of the 1d scaffold. The set of synthesized 6-nitroquinoxaline derivatives along with 1d were all subjected to antibacterial evaluation across five different bacteria species. Among the compound set, 3a displayed potent antibacterial activity against Staphylococcus aureus bacteria. 3a was further subjected to various biophysical studies to check whether the DNA structural alteration potential was still intact. The biological response of S. aureus cells upon treatment with 3a was studied using various cell biology processes, which led to the conclusion that 3d can initiate DNA damage in the S. aureus cells. Finally, the potential of 3a in disrupting preformed S.aureus and S.epidermidis biofilms was also studied.

Keywords: DNA structural change, antibacterial, intercalator, DNA superstructures, biofilms

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5593 Lexical Semantic Analysis to Support Ontology Modeling of Maintenance Activities– Case Study of Offshore Riser Integrity

Authors: Vahid Ebrahimipour

Abstract:

Word representation and context meaning of text-based documents play an essential role in knowledge modeling. Business procedures written in natural language are meant to store technical and engineering information, management decision and operation experience during the production system life cycle. Context meaning representation is highly dependent upon word sense, lexical relativity, and sematic features of the argument. This paper proposes a method for lexical semantic analysis and context meaning representation of maintenance activity in a mass production system. Our approach constructs a straightforward lexical semantic approach to analyze facilitates semantic and syntactic features of context structure of maintenance report to facilitate translation, interpretation, and conversion of human-readable interpretation into computer-readable representation and understandable with less heterogeneity and ambiguity. The methodology will enable users to obtain a representation format that maximizes shareability and accessibility for multi-purpose usage. It provides a contextualized structure to obtain a generic context model that can be utilized during the system life cycle. At first, it employs a co-occurrence-based clustering framework to recognize a group of highly frequent contextual features that correspond to a maintenance report text. Then the keywords are identified for syntactic and semantic extraction analysis. The analysis exercises causality-driven logic of keywords’ senses to divulge the structural and meaning dependency relationships between the words in a context. The output is a word contextualized representation of maintenance activity accommodating computer-based representation and inference using OWL/RDF.

Keywords: lexical semantic analysis, metadata modeling, contextual meaning extraction, ontology modeling, knowledge representation

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5592 The Inverse Problem in the Process of Heat and Moisture Transfer in Multilayer Walling

Authors: Bolatbek Rysbaiuly, Nazerke Rysbayeva, Aigerim Rysbayeva

Abstract:

Relevance: Energy saving elevated to public policy in almost all developed countries. One of the areas for energy efficiency is improving and tightening design standards. In the tie with the state standards, make high demands for thermal protection of buildings. Constructive arrangement of layers should ensure normal operation in which the humidity of materials of construction should not exceed a certain level. Elevated levels of moisture in the walls can be attributed to a defective condition, as moisture significantly reduces the physical, mechanical and thermal properties of materials. Absence at the design stage of modeling the processes occurring in the construction and predict the behavior of structures during their work in the real world leads to an increase in heat loss and premature aging structures. Method: To solve this problem, widely used method of mathematical modeling of heat and mass transfer in materials. The mathematical modeling of heat and mass transfer are taken into the equation interconnected layer [1]. In winter, the thermal and hydraulic conductivity characteristics of the materials are nonlinear and depends on the temperature and moisture in the material. In this case, the experimental method of determining the coefficient of the freezing or thawing of the material becomes much more difficult. Therefore, in this paper we propose an approximate method for calculating the thermal conductivity and moisture permeability characteristics of freezing or thawing material. Questions. Following the development of methods for solving the inverse problem of mathematical modeling allows us to answer questions that are closely related to the rational design of fences: Where the zone of condensation in the body of the multi-layer fencing; How and where to apply insulation rationally his place; Any constructive activities necessary to provide for the removal of moisture from the structure; What should be the temperature and humidity conditions for the normal operation of the premises enclosing structure; What is the longevity of the structure in terms of its components frost materials. Tasks: The proposed mathematical model to solve the following problems: To assess the condition of the thermo-physical designed structures at different operating conditions and select appropriate material layers; Calculate the temperature field in a structurally complex multilayer structures; When measuring temperature and moisture in the characteristic points to determine the thermal characteristics of the materials constituting the surveyed construction; Laboratory testing to significantly reduce test time, and eliminates the climatic chamber and expensive instrumentation experiments and research; Allows you to simulate real-life situations that arise in multilayer enclosing structures associated with freezing, thawing, drying and cooling of any layer of the building material.

Keywords: energy saving, inverse problem, heat transfer, multilayer walling

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5591 Optimization, Characterization and Stability of Trachyspermum copticum Essential Oil Loaded in Niosome Nanocarriers

Authors: Mohadese Hashemi, Elham Akhoundi Kharanaghi, Fatemeh Haghiralsadat, Mojgan Yazdani, Omid Javani, Mahboobe Sharafodini, Davood Rajabi

Abstract:

Niosomes are non-ionic surfactant vesicles in aqueous media resulting in closed bilayer structures that can be used as carriers of hydrophilic and hydrophobic compounds. The use of niosomes for encapsulation of essential oils (EOs) is an attractive new approach to overcome their physicochemical stability concerns include sensibility to oxygen, light, temperature, and volatility, and their reduced bioavailability which is due to low solubility in water. EOs are unstable and fragile volatile compounds which have strong interest in pharmaceutical due to their medicinal properties such as antiviral, anti-inflammatory, antifungal, and antioxidant activities without side effects. Trachyspermum copticum (ajwain) is an annual aromatic plant with important medicinal properties that grows widely around Mediterranean region and south-west Asian countries. The major components of the ajwain oil were reported as thymol, γ-terpinene, p-cymene, and carvacrol which provide antimicrobial and antioxidant activity. The aim of this work was to formulate ajwain essential oil-loaded niosomes to improve water solubility of natural product and evaluate its physico-chemical features and stability. Ajwain oil was obtained through steam distillation using a clevenger-type apparatus and GC/MS was applied to identify the main components of the essential oil. Niosomes were prepared by using thin film hydration method and nanoparticles were characterized for particle size, dispersity index, zeta potential, encapsulation efficiency, in vitro release, and morphology.

Keywords: trachyspermum copticum, ajwain, niosome, essential oil, encapsulation

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5590 Electrophoretic Deposition of p-Type Bi2Te3 for Thermoelectric Applications

Authors: Tahereh Talebi, Reza Ghomashchi, Pejman Talemi, Sima Aminorroaya

Abstract:

Electrophoretic deposition (EPD) of p-type Bi2Te3 material has been accomplished, and a high quality crack-free thick film has been achieved for thermoelectric (TE) applications. TE generators (TEG) can convert waste heat into electricity, which can potentially solve global warming problems. However, TEG is expensive due to the high cost of materials, as well as the complex and expensive manufacturing process. EPD is a simple and cost-effective method which has been used recently for advanced applications. In EPD, when a DC electric field is applied to the charged powder particles suspended in a suspension, they are attracted and deposited on the substrate with the opposite charge. In this study, it has been shown that it is possible to prepare a TE film using the EPD method and potentially achieve high TE properties at low cost. The relationship between the deposition weight and the EPD-related process parameters, such as applied voltage and time, has been investigated and a linear dependence has been observed, which is in good agreement with the theoretical principles of EPD. A stable EPD suspension of p-type Bi2Te3 was prepared in a mixture of acetone-ethanol with triethanolamine as a stabilizer. To achieve a high quality homogenous film on a copper substrate, the optimum voltage and time of the EPD process was investigated. The morphology and microstructures of the green deposited films have been investigated using a scanning electron microscope (SEM). The green Bi2Te3 films have shown good adhesion to the substrate. In summary, this study has shown that not only EPD of p-type Bi2Te3 material is possible, but its thick film is of high quality for TE applications.

Keywords: electrical conductivity, electrophoretic deposition, mechanical property, p-type Bi2Te3, Seebeck coefficient, thermoelectric materials, thick films

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5589 Enhanced Ripening Behaviour of Manganese Doped Cadmium Selenide Quantum Dots (Mn-doped CdSe QDs)

Authors: N. A. Hamizi, M. R. Johan, Y. H. Hor, A. N. Sabri, Y. Y. A. Yong

Abstract:

In this research, Mn-doped CdSe QDs is synthesized by using paraffin liquid as the reacting solvent and oleic acid as the ligands for Cd in order to produce Mn-doped CdSe QDs in zinc-blende crystal structure. Characterization studies for synthesized Mn-doped CdSe QDs are carried out using UV-visible and photoluminescence spectroscopy. The absorption wavelengths in UV-vis test and emission wavelengths in PL test were increase with the increases in the ripening temperature and time respectively.

Keywords: semiconductor, chemical synthesis, optical properties, ripening

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5588 Analysis of Adipose Tissue-Derived Mesenchymal Stem Cells under Atherosclerosis Microenvironment

Authors: Do Khanh Vy, Vuong Cat Khanh, Osamu Ohneda

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During atherosclerosis (AS) progression, perivascular adipose tissue-derived mesenchymal stem cells (PVAT-MSCs) are exposed to the hypoxic environment due to the oxygenic deprivation which might influence the adipose tissue-derived mesenchymal stem cells (AT-MSCs) function. Additionally, it has been reported that the angiogenic ability of subcutaneous AT-MSCs (SAT-MSCs) was impaired in the AS patients. However, up to now, the effects of AS on the characteristics and function of PVAT-MSCs have not been clarified yet. In the present study, we analyzed the AS microenvironment effects on the characteristics and function of AT-MSCs. We found that there was no significant difference in cellular morphology and differentiation ability between SAT-MSCs and PVAT-MSCs in AS patients. However, the proliferation of AS-derived PVAT-MSCs was less than those of AS-derived SAT-MSCs. Importantly, the migration of AS-derived PVAT-MSCs was faster than AS-derived SAT-MSCs. Of note, AS-derived PVAT-MSCs showed the upregulation of SDF1, which is related to the homing, and VEGF, which is related to the angiogenesis compared to those of AS-derived SAT-MSCs. Consistent with these results, AS-derived PVAT-MSCs showed the higher ability to recruit EPCs and ECs than AS-derived SAT-MSCs. In addition, EPCs and ECs which cultured in the presence of AS-derived PVAT-MSC conditioned medium showed the higher angiogenic function of the tube formation compared to those cultured in AS-derived SAT-MSC conditioned medium. This result suggests that the higher paracrine effects of AS-derived PVAT-MSCs support the angiogenic function of the target cells. Our data showed the different characteristics and functions of AT-MSCs derived from different sources of tissues. Under the AS microenvironment, it seems that the characteristics and functions of PVAT-MSCs might reflect the progression of AS. Further study will be necessary to clarify the mechanism in the future.

Keywords: atherosclerosis, mesenchymal stem cells, perivascular adipose tissue, subcutaneous adipose tissue

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5587 Phase Composition Analysis of Ternary Alloy Materials for Gas Turbine Applications

Authors: Mayandi Ramanathan

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Gas turbine blades see the most aggressive thermal stress conditions within the engine, due to high Turbine Entry Temperatures in the range of 1500 to 1600°C. The blades rotate at very high rotation rates and remove a significant amount of thermal power from the gas stream. At high temperatures, the major component failure mechanism is a creep. During its service over time under high thermal loads, the blade will deform, lengthen and rupture. High strength and stiffness in the longitudinal direction up to elevated service temperatures are certainly the most needed properties of turbine blades and gas turbine components. The proposed advanced Ti alloy material needs a process that provides a strategic orientation of metallic ordering, uniformity in composition and high metallic strength. The chemical composition of the proposed Ti alloy material (25% Ta/(Al+Ta) ratio), unlike Ti-47Al-2Cr-2Nb, has less excess Al that could limit the service life of turbine blades. Properties and performance of Ti-47Al-2Cr-2Nb and Ti-6Al-4V materials will be compared with that of the proposed Ti alloy material to generalize the performance metrics of various gas turbine components. This paper will involve the summary of the effects of additive manufacturing and heat treatment process conditions on the changes in the phase composition, grain structure, lattice structure of the material, tensile strength, creep strain rate, thermal expansion coefficient and fracture toughness at different temperatures. Based on these results, additive manufacturing and heat treatment process conditions will be optimized to fabricate turbine blade with Ti-43Al matrix alloyed with an optimized amount of refractory Ta metal. Improvement in service temperature of the turbine blades and corrosion resistance dependence on the coercivity of the alloy material will be reported. A correlation of phase composition and creep strain rate will also be discussed.

Keywords: high temperature materials, aerospace, specific strength, creep strain, phase composition

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5586 Engineering Photodynamic with Radioactive Therapeutic Systems for Sustainable Molecular Polarity: Autopoiesis Systems

Authors: Moustafa Osman Mohammed

Abstract:

This paper introduces Luhmann’s autopoietic social systems starting with the original concept of autopoiesis by biologists and scientists, including the modification of general systems based on socialized medicine. A specific type of autopoietic system is explained in the three existing groups of the ecological phenomena: interaction, social and medical sciences. This hypothesis model, nevertheless, has a nonlinear interaction with its natural environment ‘interactional cycle’ for the exchange of photon energy with molecular without any changes in topology. The external forces in the systems environment might be concomitant with the natural fluctuations’ influence (e.g. radioactive radiation, electromagnetic waves). The cantilever sensor deploys insights to the future chip processor for prevention of social metabolic systems. Thus, the circuits with resonant electric and optical properties are prototyped on board as an intra–chip inter–chip transmission for producing electromagnetic energy approximately ranges from 1.7 mA at 3.3 V to service the detection in locomotion with the least significant power losses. Nowadays, therapeutic systems are assimilated materials from embryonic stem cells to aggregate multiple functions of the vessels nature de-cellular structure for replenishment. While, the interior actuators deploy base-pair complementarity of nucleotides for the symmetric arrangement in particular bacterial nanonetworks of the sequence cycle creating double-stranded DNA strings. The DNA strands must be sequenced, assembled, and decoded in order to reconstruct the original source reliably. The design of exterior actuators have the ability in sensing different variations in the corresponding patterns regarding beat-to-beat heart rate variability (HRV) for spatial autocorrelation of molecular communication, which consists of human electromagnetic, piezoelectric, electrostatic and electrothermal energy to monitor and transfer the dynamic changes of all the cantilevers simultaneously in real-time workspace with high precision. A prototype-enabled dynamic energy sensor has been investigated in the laboratory for inclusion of nanoscale devices in the architecture with a fuzzy logic control for detection of thermal and electrostatic changes with optoelectronic devices to interpret uncertainty associated with signal interference. Ultimately, the controversial aspect of molecular frictional properties is adjusted to each other and forms its unique spatial structure modules for providing the environment mutual contribution in the investigation of mass temperature changes due to pathogenic archival architecture of clusters.

Keywords: autopoiesis, nanoparticles, quantum photonics, portable energy, photonic structure, photodynamic therapeutic system

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5585 Study on the Wave Dissipation Performance of Double-Cylinder and Double-Plate Floating Breakwater

Authors: Liu Bijin

Abstract:

Floating breakwaters have several advantages, including being environmentally friendly, easy to construct, and cost-effective regardless of water depth. They have a broad range of applications in coastal engineering. However, they face significant challenges due to the unstable effect of wave dissipation, structural vulnerability, and high mooring system requirements. This paper investigates the wave dissipation performance of a floating breakwater structure. The structure consists of double cylinders, double vertical plates, and horizontal connecting plates. The investigation is carried out using physical model tests and numerical simulation methods based on STAR-CCM+. This paper discusses the impact of wave elements, relative vertical plate heights, and relative horizontal connecting plate widths on the wave dissipation performance of the double-cylinder, double-plate floating breakwater (DCDPFB). The study also analyses the changes in local vorticity and velocity fields around the DCDPFB to determine the optimal structural dimensions. The study found that the relative width of the horizontal connecting plate, the relative height of the vertical plate, and the size of the semi-cylinder are the key factors affecting the wave dissipation performance of the DCDPFB. The transmittance coefficient is minimally affected by the wave height and the depth of water entry. The local vortex and velocity field formed around the DCDPFB are important factors for dissipating wave energy. The test section of the DCDPFB, constructed according to the relative optimal structural dimensions, showed good wave dissipation performance during offshore prototype tests. The test section of DCDPFB, constructed with optimal structural dimensions, exhibits excellent wave dissipation performance in offshore prototype tests.

Keywords: floating breakwater, wave dissipation performance, transmittance coefficient, model test

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5584 Influence of Irregularities in Plan and Elevation

Authors: Houmame Benbouali

Abstract:

Some architectural conditions required some shapes often lead to an irregular distribution of masses, rigidities and resistances. The main object of the present study consists in estimating the influence of the irregularity both in plan and in elevation which presenting some structures on the dynamic characteristics and his influence on the behavior of this structures. To do this, it is necessary to apply both dynamic methods proposed by the RPA99 (spectral modal method and method of analysis by accelerogram) on certain similar prototypes and to analyze the parameters measuring the answer of these structures and to proceed to a comparison of the results.

Keywords: irregularity, seismic, response, structure, ductility

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5583 On q-Non-extensive Statistics with Non-Tsallisian Entropy

Authors: Petr Jizba, Jan Korbel

Abstract:

We combine an axiomatics of Rényi with the q-deformed version of Khinchin axioms to obtain a measure of information (i.e., entropy) which accounts both for systems with embedded self-similarity and non-extensivity. We show that the entropy thus obtained is uniquely solved in terms of a one-parameter family of information measures. The ensuing maximal-entropy distribution is phrased in terms of a special function known as the Lambert W-function. We analyze the corresponding ‘high’ and ‘low-temperature’ asymptotics and reveal a non-trivial structure of the parameter space.

Keywords: multifractals, Rényi information entropy, THC entropy, MaxEnt, heavy-tailed distributions

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5582 Contrasting Infrastructure Sharing and Resource Substitution Synergies Business Models

Authors: Robin Molinier

Abstract:

Industrial symbiosis (I.S) rely on two modes of cooperation that are infrastructure sharing and resource substitution to obtain economic and environmental benefits. The former consists in the intensification of use of an asset while the latter is based on the use of waste, fatal energy (and utilities) as alternatives to standard inputs. Both modes, in fact, rely on the shift from a business-as-usual functioning towards an alternative production system structure so that in a business point of view the distinction is not clear. In order to investigate the way those cooperation modes can be distinguished, we consider the stakeholders' interplay in the business model structure regarding their resources and requirements. For infrastructure sharing (following economic engineering literature) the cost function of capacity induces economies of scale so that demand pooling reduces global expanses. Grassroot investment sizing decision and the ex-post pricing strongly depends on the design optimization phase for capacity sizing whereas ex-post operational cost sharing minimizing budgets are less dependent upon production rates. Value is then mainly design driven. For resource substitution, synergies value stems from availability and is at risk regarding both supplier and user load profiles and market prices of the standard input. Baseline input purchasing cost reduction is thus more driven by the operational phase of the symbiosis and must be analyzed within the whole sourcing policy (including diversification strategies and expensive back-up replacement). Moreover, while resource substitution involves a chain of intermediate processors to match quality requirements, the infrastructure model relies on a single operator whose competencies allow to produce non-rival goods. Transaction costs appear higher in resource substitution synergies due to the high level of customization which induces asset specificity, and non-homogeneity following transaction costs economics arguments.

Keywords: business model, capacity, sourcing, synergies

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5581 Revitalization of the Chinese Residential at Lasem, Indonesia

Authors: Nurtati Soewarno, Dian Duhita

Abstract:

The existence of civilization from the past is recognized by the left objects such as monuments, buildings or even a town. The relics were designed and made well, using the good quality material so it could persist a long period of time. At this moment, those relics are cultural heritage that must be preserved and the authenticity maintained. Indonesia, a country consist of various tribes with many cultural heritages, one of them is the city of Lasem. Lasem city lies in the northern part of Central Java since the Majapahit kingdom era (13th century) poses as a busy harbor city and a trading center. Lasem is one of the residences of Chinese immigrants in Java, seen by the domination of Chinese architectural building styles. The residential was built since the 15th century and the building has the courtyard which is different from other China’s building in another part of Java. This city loses ground since the trade activity experience difficulties during the Japanese colonial era and continues after the Indonesian independence time. Many Chinese people left Lasem city and let the buildings empty not maintained. This paper will present the result of observation to Chinese architectural style buildings in Lasem city which still hold out until this moment. Using typo morphology method, the case study is chosen based on the transformation type. The occurring transformation is parallel with adaptive reuse concept as an effort to revitalize the existence of the buildings. With this concept, it is expected that the buildings could be re functioned and the glory of the foretime Lasem city could be experienced again. Intervention from the local government is expected, issuing regulations, hoping the new building functions won’t ruin the cultural heritage but instead beautifies it.

Keywords: adaptive re-use, brown field area, building transformation, Lasem city

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5580 Development of Site-Specific Colonic Drug Delivery System (Nanoparticles) of Chitosan Coated with pH Sensitive Polymer for the Management of Colonic Inflammation

Authors: Pooja Mongia Raj, Rakesh Raj, Alpana Ram

Abstract:

Background: The use of multiparticulate drug delivery systems in preference to single unit dosage forms for colon targeting purposes dates back to 1985 when Hardy and co-workers showed that multiparticulate systems enabled the drug to reach the colon quickly and were retained in the ascending colon for a relatively long period of time. Methods: Site-specific colonic drug delivery system (nanoparticles) of 5-ASA were prepared and coated with pH sensitive polymer. Chitosan nanoparticles (CTNP) bearing 5-Amino salicylic acid (5-ASA) were prepared, by ionotropic gelation method. Nanoparticulate dosage form consisting of a hydrophobic core enteric coated with pH-dependent polymer Eudragit S-100 by solvent evaporation method, for the effective delivery of drug to the colon for treatment of ulcerative colitis. Results: The mean diameter of CTNP and ECTNP formulations were 159 and 661 nm, respectively. Also optimum value of polydispersity index was found to be 0.249 [count rate (kcps) was 251.2] and 0.170 [count rate (kcps) was 173.9] was obtained for both the formulations respectively. Conclusion: CTNP and Eudragit chitosan nanoparticles (ECTNP) was characterized for shape and surface morphology by scanning electron microscopy (SEM) appeared to be spherical in shape. The in vitro drug release was investigated using USP dissolution test apparatus in different simulated GIT fluids showed promising release. In vivo experiments are in further proceeding for fruitful results.

Keywords: colon targeting, nanoparticles, polymer, 5-amino salicylic acid, edragit

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5579 Influence of the Induction Program on Novice Teacher Retention In One Specialized School in Nur-Sultan

Authors: Almagul Nurgaliyeva

Abstract:

The phenomenon of novice teacher attrition is an urgent issue. The effective mechanisms to increase the retention rate of novice teachers relate to the nature and level of support provided at an employing site. This study considered novice teacher retention as a motivation-based process, which is based on a variety of support activities employed to satisfy novice teachers’ needs at an early career stage. The purpose of the study was to examine novice teachers’ perceptions of the effectiveness of the induction program and other support structure(s) at a secondary school in Nur-Sultan. The study was guided by Abraham Maslow’s (1943) theory of motivation. Maslow’s hierarchy of needs was used as a theoretical framework to identify the novice teachers’ primary needs and the extent to which the induction programs and other support mechanisms provided by the school administrators fulfill those needs. One school supervisor and eight novice teachers (four current and four former novice teachers) with a maximum of four years of teaching experience took part in the study. To investigate the perspectives and experiences of the participants, an online semi-structured interview was utilized. The responses were collected and analyzed. The study revealed four major challenges: educational, personal-psychological, sociological, and structural which are seen as the main constraints during the adaptation period. Four induction activities, as emerged from the data, are being carried out by the school to address novice teachers’ challenges: socialization activities, mentoring programs, professional development, and administrative support. These activities meet novice teachers’ needs and confront the challenges they face. Sufficient and adequate support structures provided to novice teachers during their first years of working experience is essential, as they may influence their decision to remain in the teaching profession, thereby reducing the attrition rate. The study provides recommendations for policymakers and school administrators about the structure and the content of induction program activities.

Keywords: beginning teacher induction, induction programme, orientation programmes, adaptation challenges, novice teacher retention

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5578 Dynamic Wind Effects in Tall Buildings: A Comparative Study of Synthetic Wind and Brazilian Wind Standard

Authors: Byl Farney Cunha Junior

Abstract:

In this work the dynamic three-dimensional analysis of a 47-story building located in Goiania city when subjected to wind loads generated using both the Wind Brazilian code, NBR6123 (ABNT, 1988) and the Synthetic-Wind method is realized. To model the frames three different methodologies are used: the shear building model and both bi and three-dimensional finite element models. To start the analysis, a plane frame is initially studied to validate the shear building model and, in order to compare the results of natural frequencies and displacements at the top of the structure the same plane frame was modeled using the finite element method through the SAP2000 V10 software. The same steps were applied to an idealized 20-story spacial frame that helps in the presentation of the stiffness correction process applied to columns. Based on these models the two methods used to generate the Wind loads are presented: a discrete model proposed in the Wind Brazilian code, NBR6123 (ABNT, 1988) and the Synthetic-Wind method. The method uses the Davenport spectrum which is divided into a variety of frequencies to generate the temporal series of loads. Finally, the 47- story building was analyzed using both the three-dimensional finite element method through the SAP2000 V10 software and the shear building model. The models were loaded with Wind load generated by the Wind code NBR6123 (ABNT, 1988) and by the Synthetic-Wind method considering different wind directions. The displacements and internal forces in columns and beams were compared and a comparative study considering a situation of a full elevated reservoir is realized. As can be observed the displacements obtained by the SAP2000 V10 model are greater when loaded with NBR6123 (ABNT, 1988) wind load related to the permanent phase of the structure’s response.

Keywords: finite element method, synthetic wind, tall buildings, shear building

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5577 Advantages of Utilizing Post-Tensioned Stress Ribbon Systems in Long Span Roofs

Authors: Samih Ahmed, Guayente Minchot, Fritz King, Mikael Hallgren

Abstract:

The stress ribbon system has numerous advantages that include but are not limited to increasing overall stiffness, control deflections, and reduction of materials consumption, which in turn, reduces the load and the cost. Nevertheless, its use is usually limited to bridges, in particular, pedestrian bridges; this can be attributed to the insufficient space that buildings' usually have for end supports, and/or back- stayed cables, that can accommodate the expected high pull-out forces occurring at the cables' ends. In this work, the roof of Västerås Travel Center, which will become one of the longest cable suspended roofs in the world, was chosen as a case study. The aim was to investigate the optimal technique to model the post-tensioned stress ribbon system for the roof structure using the FEM software SAP2000 and to assess any possible reduction in the pull-out forces, deflections, and concrete stresses. Subsequently, a conventional cable suspended roof was simulated using SAP2000, and compared to the post-tension stress ribbon system in order to examine the potential of the latter. Moreover, the effects of temperature loads and support movements on the final design loads were examined. Based on the study, a few practical recommendations concerning the construction method and the iterative design process, required to meet the architectural geometrical demands, are stated by the authors. The results showed that the post-tensioned stress ribbon system reduces the concrete stresses, overall deflections, and more importantly, reduces the pull-out forces and the vertical reactions at both ends by up to 16% and 11%, respectively, which substantially reduces the design forces for the support structures. The magnitude of these reductions was found to be highly correlated to the applied prestressing force, making the size of the prestressing force a key factor in the design.

Keywords: cable suspended, post-tension, roof structure, SAP2000, stress ribbon

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5576 Characterization of Biogenic Silver Nanoparticles by Salvadora persica Leaves Extract and its Application Against Some MDR Pathogens E. Coli and S. Aureus

Authors: Mudawi M. Nour

Abstract:

Background: Now a days, the multidisciplinary scientific research conception in the field of nanotechnology has witnessed development with regard to the numerous applications and synthesis of nanomaterials. Objective: The current investigation has been conducted with the main focus on the green synthesis of silver nanoparticles from the leaves of Salvadora persica and its antibacterial activity against MDR pathogens E. coli and S. aureus. Methodology: Silver nanoparticles (AgNPs) were prepared after addition of aqueous extract of Salvadora persica leaves. The UV-Vis spectrophotometer, Transmission Electron Microscopy (TEM), zeta potential and Scanning Electron Microscopy (SEM) were employed to detect the particle size and morphology, besides Fourier transform infra-red spectrometer (FTIR) analysis was performed to determine the capping and stabilizing agents in the extract. Antibacterial assay for the biogenic AgNPs was conducted against E. coli and S. aureus. Results: Color change of the mixture from yellow to dark brown is the first indication to AgNPs formation. Furthermore, 420 nm was the peak value for UV-Vis spectroscopy absorption of the mixture. Besides, TEM and SEM micrographs showed wide variability in the diameter of smaller NPs aggregated together with spherical shapes, and zeta sizer showed about 153.3 nm as an average size of nanoparticles. Microbial suppression was noticed for the tested microorganisms. Furthermore, with the help of FTIR analysis, the biomolecules that act as capping and stabilizing agents of AgNPs are proteins and phenols present in the plant extract. Conclusion: Salvadora persica leaves extract act as a reducing and stabilizing agent for the synthesis of AgNPs, keeping its ability to suppress the MDR pathogen.

Keywords: green synthesis, FTIR, MDR pathogen, salvadora persica

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5575 Effects of Tillage and Poultry Manure on Soil Properties and Yam Performance on Alfisol in Southwest Nigeria

Authors: Adeleye Ebenezer Omotayo

Abstract:

The main effects of tillage, poultry manure and interaction effects of tillage-poultry manure combinations on soil characteristics and yam yield were investigated in a factorial experiment involving four tillage techniques namely (ploughing (p), ploughing plus harrowing (PH), manual ridging (MR), manual heaping (MH) and poultry manure at two levels 0 t ha-1 and 10 t ha-1 arranged in split-plot design. Data obtained were subjected to analysis of variance using Statistical Analysis System (SAS) Institute Package. Soil moisture content, bulk density and total porosity were significantly (p>0.05) influenced by soil tillage techniques. Manually heaped and ridged plots had the lowest soil bulk density, moisture content and highest total porosity. The soil total N, exchangeable Mg, k, base saturation and CEC were better enhanced in manually tilled plots. Soil nutrients status declined at the end of the second cropping for all the tillage techniques in the order PH>P>MH>MR. Yam tuber yields were better enhanced in manually tilled plots than mechanically tilled plots. Poultry manure application reduced soil bulk density, temperature, increased total porosity and soil moisture content. It also improved soil organic matter, total N, available P, exchangeable Mg, Ca, K and lowered exchange acidity. It also increased yam tuber yield significantly. Tillage techniques plots amended with poultry manure enhanced yam tuber yield relative to tillage techniques plots without poultry manure application. It is concluded that yam production on alfisol in Southwest Nigeria requires loose soil structure for tuber development and that the use of poultry manure in combination with tillage is recommended as it will ensure stability of soil structure, improve soil organic matter status, nutrient availability and high yam tuber yield. Also, it will help to reduce the possible deleterious effects of tillage on soil properties and yam performance.

Keywords: ploughing, poultry manure, yam, yield

Procedia PDF Downloads 254
5574 Hydrodynamics of Undulating Ribbon-fin and Its Application in Bionic Underwater Robot

Authors: Zhang Jun, Zhai Shucheng, Bai Yaqiang, Zhang Guoping

Abstract:

The Gymnarchus Niioticus fish(GNF) cruises generally with high efficiency by undulating ribbon-fin propulsion while keeping its body for straight line. The swing amplitude of GNF fins is usually in 60° to 90°, and in normal state the amplitude is close to 90°, only in the control of hovering or swimming at very low speed, the amplitude is smaller (about 60°). It provides inspiration for underwater robot design. In the paper, the unsteady flow of undulating ribbon-fin propulsion is numerical simulated by the dynamic grid technique including spring-based smoothing model and local grid remeshing to adapt to the fin surface significantly deforming, and the swing amplitude of fin ray reaches 850. The numerical simulation method is validated by thrust experiments. The spatial vortex structure and its evolution with phase angle is analyzed. The propulsion mechanism is investigated by comprehensive analysis of the hydrodynamics, vortex structure, and pressure distribution on the fin surface. The numerical results indicates that there are mainly three kinds of vortexes, i.e. streamwise vortex, crescent vortex and toroidal vortex. The intensity of streamwise vortex is the strongest among all kinds of vortexes. Streamwise vortexes and crescent vortexes all alternately distribute on the two sides of mid-sagittal plane. Inside the crescent vortexes is high-speed flow, while outside is low-speed flow. The crescent vortexes mainly induce high-speed axial jet, which produces the primary thrust. This is hydrodynamic mechanism undulating ribbon-fin propulsion. The streamwise vortexes mainly induce the vertical jet, which generates the primary heave force. The effect on hydrodynamics of main geometry and movement parameters including wave length, amplitude and advanced coefficients is investigated. A bionic underwater robot with bilateral undulating ribbon-fins is designed, and its navigation performance and maneuverability are measured.

Keywords: bionic propulsion, mobile robot, underwater robot, undulating ribbon-fins

Procedia PDF Downloads 267