Добірка наукової літератури з теми "Research Subject Categories – INTERDISCIPLINARY RESEARCH AREAS - Materials Engineering"

Purpose The purpose of this paper is to measure the degree of interdisciplinary collaboration in Big Data research based on the co-occurrences of subject categories using Stirling’s diversity index and specialization index. Design/methodology/approach Interdisciplinarity was measured utilizing the descriptive statistics of disciplines, network indicators showing relationships between disciplines and within individual disciplines, interdisciplinary communities, Stirling’s diversity index and specialization index, and a strategic diagram revealing the development status and trends of discipline communities. Findings Comprehensively considering all results, the degree of interdisciplinarity of Big Data research is increasing over time, particularly, after 2013. There is a high level of interdisciplinarity in Big Data research involving a large number of disciplines, but it is unbalanced in distribution. The interdisciplinary collaborations are not intensive on the whole; most disciplines are aggregated into a few distinct communities with computer science, business and economics, mathematics, and biotechnology and applied microbiology as the core. Four major discipline communities in Big Data research represent different directions with different development statuses and trends. Community 1, with computer science as the core, is the most mature and central to the whole interdisciplinary network. Accounting for all network indicators, computer science, engineering, business and economics, social sciences, and mathematics are the most important disciplines in Big Data research. Originality/value This study deepens our understanding of the degree and trend of interdisciplinary collaboration in Big Data research through a longitudinal study and quantitative measures based on two indexes. It has practical implications to study and reveal the interdisciplinary phenomenon and characteristics of related developments of a specific research area, or to conduct comparative studies between different research areas.

Design research topics attract exponentially more attention and consideration among researchers. This study is the first research article that endeavors to analyze selected design research publications using an advanced approach called “text mining”. This approach speculates its results depending on the existence of a research term (i.e., keywords), which can be more robust than other methods/approaches that rely on contextual data or authors’ perspectives. The main aim of this research paper is to expand knowledge and familiarity with design research and explore future research directions by addressing the gaps in the literature; relying on the literature review, it can be stated that the research area in the design domain still not built-up a theory, which can unify the field. In general, text mining with these features allows increased validity and generalization as compared to other approaches in the literature. We used a text mining technique to collect data and analyzed 3553 articles collected in 10 journals using 17,487 keywords. New topics were investigated in the domain of design concepts, which included attracting researchers, practitioners, and journal editorial boards. Such issues as co-innovation, ethical design, social practice design, conceptual thinking, collaborative design, creativity, and generative methods and tools were subject to additional research. On the other hand, researchers pursued topics such as collaborative design, human-centered design, interdisciplinary design, design education, participatory design, design practice, collaborative design, design development, collaboration, design theories, design administration, and service/product design areas. The key categories investigated and reported in this paper helped in determining what fields are flourishing and what fields are eroding.

The article presents an analysis of research on biotechnology over the past 20 years based on the materials of patent and bibliometric databases. The dynamics of publication activity in the category ‘Biotechnology and applied Microbiology’ by years, thematic categories, and countries is revealed. The leading states in various fields are identified. The entry of Russian research into the world scientific space is determined, and priority vectors of domestic developments are noted. The most productive categories of biotechnological research within the country and with international participation are shown. Conclusions are drawn about developing areas of domestic research and areas with negative publication dynamics. Based on the subject matter of articles, the number of publications and citations, a list of Russian organizations for which biotechnology is the main field of activity has been compiled. The authors of the article review patent activity in the field of biotechnology, highlight the most relevant areas of patent activity in medicine, pharmacy, and agriculture. The most significant domestic inventions in recent years are noted. Conclusions are drawn about the high technical level of domestic inventions and their practical significance. The necessity of introducing scientific research into practical developments through the creation of various firms and enterprises on the basis of scientific institutions is indicated.

Purpose: The main objective of the research is to identify a competence gap in "Industry4.0" – the difference between the competencies currently acquired by students at universities with a technical and economic profile, and the competencies desired by companies from the industrial processing sector. Design/methodology/approach: Empirical material was obtained in two studies. The first survey was conducted among 120 companies in the industrial engineering sector, while the second was carried out among over a thousand students and graduates of economic and technical universities. Findings: This work contributes to an in-depth understanding of companies’ needs regarding “Manager 4.0” competencies, and enables the identification of existing educational gaps. Our research results show that there is a competence gap on the labour market in each of the analysed categories of competencies: social, personal, managerial, technical and professional. At the same time, some differences are visible between students of economic and technical universities. The findings of the study suggest the need to redesign student education programs at universities so as to provide interdisciplinary education taking into account key competencies for Industry 4.0. Research limitations/implications: We identified three limitations of our research, resulting both from the size of the research sample of the analyzed comapanies, the possible ambiguity of the respondents' understanding of the examined competences (ambiguity of their interpretations) and their mutual interdependencies, as well as the subjective assessment of the students themselves. Practical and social implications: The study indicated the need for specific employee competencies, the development of which requires interdisciplinary study programmes in areas including production engineering and management. Besieds, the results of our research are particularly important for adapting employee training systems. We assume that the development of new training programs best suited to the needs of the market (need for specific employee competencies) should be done through cooperation between companies in the industrial processing sector and the academic community. Originality/value: The conclusions of the research shed new light on requirements regarding managerial positions in companies from the industrial processing sector, by indicating the need to modify curricula at universities in selected areas of competence. Keywords: Industry 4.0, Manager 4.0, human resources, managerial competencies. Category of the paper: Research paper.

The advent of the miniaturization approach has influenced the research trends in almost all disciplines. Bioengineering is one of the fields benefiting from the new possibilities of microfabrication techniques, especially in cell and tissue culture, disease modeling, and drug discovery. The limitations of existing 2D cell culture techniques, the high time and cost requirements, and the considerable failure rates have led to the idea of 3D cell culture environments capable of providing physiologically relevant tissue functions in vitro. Organ-on-chips are microfluidic devices used in this context as a potential alternative to in vivo animal testing to reduce the cost and time required for drug evaluation. This emerging technology contributes significantly to the development of various research areas, including, but not limited to, tissue engineering and drug discovery. However, it also brings many challenges. Further development of the technology requires interdisciplinary studies as some problems are associated with the materials and their manufacturing techniques. Therefore, in this paper, organ-on-chip technologies are presented, focusing on the design and fabrication requirements. Then, state-of-the-art materials and microfabrication techniques are described in detail to show their advantages and also their limitations. A comparison and identification of gaps for current use and further studies are therefore the subject of the final discussion.

Achieving zero energy consumption in buildings is one of the most effective ways of achieving ‘carbon neutrality’ and contributing to a green and sustainable global development. Currently, BIPV systems are one of the main approaches to achieving zero energy in buildings in many countries. This paper presents the evolution of BIPV systems and predicts their future trends by deriving a base sample of core papers on BIPV systems from 2012 to 2022 from the Web of Science core database and conducting a bibliometric study using CiteSpace scientific visualisation software. To gain a deeper understanding and grasp of the research progress of BIPV systems, research group discovery, research hotspot analysis, and research frontier detection of the relevant literature were conducted. (1) Research groups on the topic were summarised through author coupling network, publication distribution, and country mapping analysis; (2) Research hotspots on the topic were explored through keyword co-occurrence, keyword emergence, and time zone map analysis; (3) Research hotspots on the topic were explored through literature co-citation timeline maps, literature co-citation categories, and literature co-citation clustering analysis to detect the frontiers of research in the field. Finally, we conclude that research trends in BIPV systems are mainly in the areas of heat transfer, thermal performance, renewable energy, solar cell and renewable building materials, and evaluation systems. In the future, BIPV research and applications will move towards interdisciplinary and multinational cooperation, which will maximise the benefits of clean energy conversion in buildings. It will also provide researchers and practitioners with a clearer understanding of BIPV research trends and hotspots, and provide new directions for future research.

Analysis of forensic science practice indicates that object range and number of performed construction and engineering researches are constantly increasing. Considering relevance of this kind of forensic science as for the investigation of criminal proceedings and for other types of legal proceedings, the basic provisions related to the theoretical base formation of forensic construction and engendering examinations in its classification aspect are considered. Currently, the lists of types of forensic examinations and forensic expert area of specializations are valid in Ukraine. According to these lists qualification of a forensic expert is assigned to experts of forensic science institutions the Ministry of Justice of Ukraine, as well as to specialists who do not work in state specialized institutions. These Lists are annexes to the Regulation: On Qualification Commissions and Certification of Forensic Experts approved by the No. 301/5 order of the Ministry of Justice of Ukraine dated 03.03.2015. According to the specified document, as separate types of forensic examinations, forensic construction engineering, forensic land lot evaluation forensic building evaluation, forensic building evaluation and forensic road examination on corresponding types of expert areas of specialization are recorded. The subject of forensic construction engineering examination and land lot evaluation should be considered factual data and circumstances of the case (production) established on the basis of specialized expertise in construction field having evidentiary value for any type of legal proceedings while research on relevant construction objects: real estate, building materials, structures and related technical documentation. Thus, technical content of construction engineering examinations and forensic land lot evaluations involves forensic construction engineering implementation by examining relevant engineering sites analyzing technical documentation within the subject and tasks of the specified categories of examinations by the relevant subject by applying the appropriate system of research methods. These features distinguish them in independent kinds of forensic science.

Tissue spheroids consist of a three-dimensional model of cells which is capable of imitating the complicated composition of healthy and unhealthy human tissue. Due to their unique properties, they can bring innovative solutions to tissue engineering and regenerative medicine, where they can be used as building blocks for the formation of organ and tissue models used in drug experimentation. Considering the rapid transformation of the health industry, it is crucial to assess the research dynamics of this field to support the development of innovative applications. In this research, a scientometric analysis was performed as part of a Competitive Technology Intelligence methodology, to determine the main applications of tissue spheroids. Papers from Scopus and Web of Science published between 2000 and 2019 were organized and analyzed. In total, 868 scientific publications were identified, and four main categories of application were determined. Main subject areas, countries, cities, authors, journals, and institutions were established. In addition, a cluster analysis was performed to determine networks of collaborations between institutions and authors. This article provides insights into the applications of cell aggregates and the research dynamics of this field, which can help in the decision-making process to incorporate emerging and innovative technologies in the health industry.

Structural DNA nanotechnology is a pioneering biotechnology that presents the opportunity to engineer DNA-based hardware that will mediate a profound interface to the nanoscale. To date, an enormous library of shaped 3D DNA nanostructures have been designed and assembled. Moreover, recent research has demonstrated DNA nanostructures that are not only static but can exhibit specific dynamic motion. DNA nanostructures have thus garnered significant research interest as a template for pursuing shape and motion-dependent nanoscale phenomena. Potential applications have been explored in many interdisciplinary areas spanning medicine, biosensing, nanofabrication, plasmonics, single-molecule chemistry, and facilitating biophysical studies. In this review, we begin with a brief overview of general and versatile design techniques for 3D DNA nanostructures as well as some techniques and studies that have focused on improving the stability of DNA nanostructures in diverse environments, which is pivotal for its reliable utilization in downstream applications. Our main focus will be to compile a wide body of existing research on applications of 3D DNA nanostructures that demonstrably rely on the versatility of their mechanical design. Furthermore, we frame reviewed applications into three primary categories, namely encapsulation, surface templating, and nanomechanics, that we propose to be archetypal shape- or motion-related functions of DNA nanostructures found in nanoscience applications. Our intent is to identify core concepts that may define and motivate specific directions of progress in this field as we conclude the review with some perspectives on the future.

When lessons of linguodidactics are organized in a master course within the framework of the pedagogical program «Language Education», the literal understanding of the definition of linguodidactics as a general theory of mastering a foreign language in the learning environment often leads to the fact that undergraduates studying linguodidactics as an academic subject consider only theoretical issues. Understanding the relationship between linguodidactics and methods of teaching foreign languages as a relationship between theory and practice narrows the scope of the subject. As a result, the competencies included in its program are formed fragmentarily, i.e. the objectives of this subject contain only the knowledge of the theory which excludes the practical implementation of linguodidactic skills. The article describes linguodidactic skills and analyzes the experience of solving the stated problem by means of creating a system of practical work of undergraduates in the process of studying linguodidactics. The proposed training course is integrative. It combines fundamental and interdisciplinary areas in linguodidactics, and presupposes a smooth transition from studying the problems of the interaction of linguistic theory with the practice of teaching foreign languages to considering linguodidactic models of mastering a foreign language and forming a multicultural linguistic personality. The possibility of undergraduates’ putting into practice linguodidactic knowledge makes their theoretical reports more profound and instructive due to their examples from the practice of teaching foreign languages that confirm their theoretical propositions. It also stimulates their critical attitude to different teaching materials. The effectiveness of the organization of practical work at the lessons of linguodidactics is also a result of studying the interrelated modules of the subject and passing from a theoretical analysis of the process of mastering a foreign language to creating your own teaching materials on a strictly scientific basis. The research shows that the academic subject «Linguodidactics» has unlimited potential for the scientific organization of the educational and methodical work of future masters of science.

2D material-based nanoelectromechanical systems have emerged as excellent tools for force measurement with extreme sensitivity levels. Most sensing methods with 2D nanoelectromechanical (2D NEMS) systems utilize frequency tuning of the resonant mode in response to external stimuli. However, the interaction of the harsh external stimulus with the delicate 2D NEMS limited these devices’ utility only in the research labs. We propose a fabrication and packaging method for 2D NEMS devices to extend their application outside the research labs. Under the proposed scheme, the 2D NEMS is coupled to the external stimulus through substrate strain. The substrate acts as a protective barrier between the NEMS and the environment. At the same time, the substrate also influences the strain on the 2D NEMS. The external stimulus changes the strain on the substrate and hence on the 2D NEMS device. The strain change on 2D NEMS changes the frequency of vibration modes. 2D materials such as graphene have a high Young’s modulus. High Young’s modulus allows the strain to frequency transductions with high accuracy and sensitivity. We report the most straightforward application of this scheme for pressure sensing with a responsivity of 20Hz/Pa. Using the proposed scheme, we also demonstrate the ability to utilize duffing nonlinear response of the graphene resonator for pressure sensing. The resonant response of the 2D nanoresonators becomes nonlinear, even at very small excitation voltages. The nonlinear response of the 2D nanoresonators shows sharp amplitude jumps at the bifurcation points and hysteresis. We utilize the sharp amplitude jumps to realize the bifurcation amplifier for pressure sensing. While the hysteresis in the frequency response is used to demonstrate basic logic operations such as OR, AND, and XOR with pressure pulse as input and vibration amplitude as output. The external stimulus can also have a dynamic variation that can excite the substrate’s vibration modes. In this case, the frequency tuning of the 2D NEMS is also dynamic as it follows the strain on the substrate. Utilizing this principle, we report the ability of the 2D NEMS to track the dynamic stimulus with a frequency component as high as 40kHz. Characterizing time-varying stimuli is crucial for accelerometers, acoustic sensors, and vibrometers. We demonstrate the use of highly responsive 2D nanoresonators for such dynamic sensing. Since the proposed 2D NEMS package allows external stimulus to couple to the 2D NEMS efficiently, the 2D NEMS is also susceptible to various environmental noise sources. We use the Allan Deviation of the frequency fluctuations to study the performance of these devices against noise. The measurements reveal that the primary cause of the frequency fluctuations of the 2D NEMS is the temperature of the surrounding air. These measurements provide crucial insights into designing a sensor with the required sensitivity, bandwidth and noise isolation. The barrier-substrate design can be changed according to specific applications to achieve the intended transduction. This concept can be extended easily for sensing inertial forces, biological stimuli, and temperature.

Quantitative diffusion analysis in multicomponent metallic systems has been a formidable task historically and despite decades of research, most of the diffusivity estimations were limited to interdiffusion and some intrinsic diffusion coefficients in binary systems and interdiffusion coefficients in a few ternary systems until recently. The experimental complications associated with the need to intersect (n-1) serpentine diffusion paths in the n dimensional space for determining the 〖(n-1)〗^2 interdiffusion coefficients lead to various approaches like average diffusivity, square root diffusivity estimations that approximate a representative value of the diffusivity across a composition range from a single experiment. However, these values are not material constants and do not provide any information about the atomic interactions. This lack of diffusivity data in multicomponent systems has hampered the development of mobility databases essential for various simulations and physico-chemical studies of materials. This work resolves the issues with quantitative multicomponent diffusion analysis via several newly proposed methods that solves the issue of intersecting diffusion paths through the application of special constrained diffusion paths. The equations necessary to apply these methods are derived and their application is discussed mathematically and applied experimentally to the model alloy system, the NiCoFeCr equiatomic multiprincipal element alloy to compare with available radiotracer data measured for this system. The work first employs the pseudo-binary diffusion couple approach that develops a rectilinear diffusion path in the multicomponent space to the NiCoFeCr system to estimate the tracer coefficients from the intrinsic coefficients at the marker plane. The mathematical formulations derived for the same justify its namesake and the obtained tracer coefficients can be used to back calculate the intrinsic and interdiffusion coefficients. The pseudo-ternary method improves on the shortcomings of the pseudo-binary diffusion couple method and enables the estimation of tracer coefficients of three components by crossing two constrained diffusion paths in a 2d plane in addition to the main and cross interdiffusion coefficients. The body diagonal method originally proposed for determination of interdiffusion coefficients is modified here to determine the tracer coefficients of all components using only two diffusion profiles thus reducing the errors associated with crossing (n-1).paths per the original approach. This work then explores the possibilities of crossing dissimilar constrained diffusion paths by crossing pseudo ternaries of different types. Strategically crossing a rectilinear pseudo-binary diffusion path with a serpentine conventional (body diagonal) diffusion path overcomes all the previous drawbacks of pseudo binary, pseudo ternary and body diagonal methods to determine the full set of diffusivities at any desired composition and generalizes the constrained diffusion path approach to any order multicomponent system. The obtained tracer coefficients show a good match with the diffusivities measured in radio tracer experiments. Finally, based on the ideas from the constrained diffusion path experiments in the NiCoFeCr system, a constrained path approach is devised to measure the diffusivities in an Al based NiCoFeCr multiprincipal element alloy system which was not possible earlier due to unavailability of radio isotopes and the complexities of interdiffusion experiments in higher order systems. The obtained tracer diffusivities, show an excellent match with the trends extrapolated from lower order systems. Calculated intrinsic and interdiffusion coefficients demonstrate the importance of vacancy wind effect as well as the issues with using diffusivities having different dependent components to make predictions on diffusion trends among different elements.

Biomedical research aims to gain deeper insights into the mechanisms of human pathophysiology to develop improved therapies and diagnostics. Despite significant advances made in the understanding and treatment of human diseases, many bottlenecks persist in successful clinical translation. Conventional culture techniques and animal models suffer from various limitations that fail to recapitulate human physiology and impede the clinical translation of therapies. Among various human diseases, cardiovascular diseases account for the highest number of deaths worldwide. Similarly, skeletal muscle disorders are the leading contributor to disability across the globe. Given the enormous health burden associated with ailments of cardiac and skeletal muscles, the broad goal of this work was to engineer tissue-mimetic templates for these tissues that can serve as reliable in vitro disease models. Toward this goal, simplified methods were standardized to obtain functionally superior primary cardiomyocytes and skeletal myotubes as a robust source of cells for these models. Alongside this, an unconventional and cost-effective surface coating, keratin, derived from human hair was reported to be effective and found comparable to ECM-derived proteins, fibronectin and gelatin, in supporting primary cardiomyocyte culture. Thereafter, microscale and nanoscale surfaces were designed and utilized for gaining unique insights into the cardiac and skeletal myocytes function in normal as well as the diseased state. Specifically, UV lithography and etching techniques were used to create micro-ridges as an organotypic platform to study cardiac hypertrophy and live calcium currents in cardiomyocytes. It was established that aligned cardiomyocytes showed an enhanced response to hypertrophic cues as compared to the unaligned ones and exhibited unidirectional flow of calcium currents. This approach was further extended to develop a potential antioxidant and anti-hypertrophic cardiac patch using PCL and PCL-gelatin electrospun nanofibers decorated with cerium oxide nanoparticles. The cardiomyocytes grown on ceria decorated PCLG nanofibers showed reduced ROS production in the presence of hydrogen peroxide and rescued hypertrophic response when treated with phenylephrine, a GPCR agonist. Furthermore, screening for a variety of engineered substrates was done to retain skeletal myotubes in culture for longer durations, which often detached on smooth surfaces. A nanofibrous platform was thus optimized and investigated as a disease model for muscle degeneration using western blotting and immunofluorescence techniques. Overall, the study revealed different aspects of culturing skeletal myotubes in comparison to cardiomyocytes. This work highlighted the cell-dependent response to topography even among structurally similar cell types. The developed platforms integrating primary cells and anisotropic substrates allowed to achieve precise cellular architecture and study their function in specific pathophysiological conditions. An improved understanding of alterations in cell function in response topography may lead to the development of laboratory models that better recapitulate the in vivo milieu than conventional culture and thereby improve the translation of devised therapies from bench to bedside.

Over 400 million patients suffer from urinary bladder-associated physiological disorders globally, which often necessitate surgical intervention for a reconstructive procedure. The current gold standard for bladder reconstruction, an autologous graft, is proven not to be an ideal substitute in clinics. Such unmet clinical needs drive the continuous surge for structural and functional substitutes of urinary tissues, including ureters, bladder-wall, and urethra. Against this backdrop, the present dissertation explores a biomaterial-based, functionalised alloplastic platform for urological reconstruction. This strategy for an alloplastic urinary tissue encompasses a biostable, 'off-the-shelf' available therapeutic option that simplifies and shortens surgical treatment. Furthermore, it presents the potential to evade the challenges and complications of autografts and scaffold-based regenerative techniques. Considering the prerequisites of a urological alloplast, the combination of polydimethylsiloxane and thermoplastic polyurethanes (TPU/PDMS) is deemed most advantageous. The synergistic integration of varying contents of PDMS within the molten TPU matrix is realised through a processing methodology of dynamic vulcanisation (DV). The experimental outcomes are evaluated and correlated with different phenomenological models to understand DV induced strengthening of structure. The theoretical predictions, in conjunction with material property characterisation, allow a better understanding of the improved interfacial behaviour and superior performance of the crosslinked polymer system. The in situ compatibilised blends are further investigated for clinically relevant viscoelastic properties to sustain high pressure, large distensions, and surgical handling/manipulation. Moreover, non-exhaustive chemical strategies are harnessed to counter urinary tract infections through the covalent incorporation of polycationic moieties. The new generation alloplasts, endowed with contact killing surfaces, are assessed for their efficacy in pathogenically infected artificial urine. In addition, the adhesion and proliferation of murine fibroblasts on different polymeric compositions to establish their cytocompatibility. Building further upon the knowledge of the antibacterial and antifouling activity of polycationic modifications, layer-by-layer (LbL) assembled multifunctional surface grafting are conceived to sustain long-term stability in a urinary environment, to suppress encrustation and biofilm formation. The performance of the single-step and LbL-grafted blends is benchmarked against the conventional urological alloplasts, using a customised lab-scale bioreactor set-up. Post-six weeks of incubation in the dynamic assembly simulating ureasepositive microbial infection, the contact-active blends exhibited a remarkable ability to resist calcium and magnesium encrustation, while retaining adequate grafting integrity. As high as 4-fold log reduction in the planktonic growth of bacterial strains associated with bladder stones and renal calculi is recorded. In vitro cellular assessment is carried out with human keratinocytes and human embryonic kidney cells to evaluate the cytocompatibility of the surface grafted blends against the medical-grade control polymer. Finally, the optimum LbL grafted formulations are investigated for their performance in a phase-I pre-clinical study utilising human urine samples collected from 129 patients. The newly developed blends meet the clinically desirable attributes and present a strong potential as a stable, contact-active, antiencrustation biomaterial platform for urinary implantation. Summarising, this dissertation contemplates the new-generation, infection and encrustationresistant alloplasts. In pursuit of this vision, multifunctional polymeric biomaterials are designed to sustain desirable performance in a urinary environment. These next-gen biomaterials pave the way for an alloplastic platform that can integrate into clinical practice to improve the quality of modern urological treatment.

The need and demand for continuous high-speed, energy-efficient hardware advancement is undisputed. Traditional computing system with von Neumann architecture leads to high energy consumption and latency due to a huge amount of data transfer between the separated memory unit and the logic unit. In response to this discrepancy, extensive research has been conducted to develop brain-inspired electronic devices that can provide alternate computing platforms needed for implementing hardware neural networks. Artificial synapse, which emulates the dynamics of biological synapses, such as “update” and “memorize,” is one approach toward solid-state implementation of bio-inspired devices. Recently, two-dimensional (2D) van der Waals (vdW) materials have been actively explored for such artificial synapses. The distinctive electronic, optoelectronic, and mechanical properties of two-dimensional (2D) materials make these quite attractive for a wide variety of applications. This thesis explores the electronic and optoelectronic properties of 2D materials for mimicking the synaptic performance of the neuron. Materials of interest include MoS2, which is semiconducting, and α-In2Se3, a ferroelectric semiconducting material, investigated as active elements for synaptic applications. In the first part of the dissertation, we try to understand the working mechanism, i.e., charge trapping and de-trapping in synaptic devices using MoS2 as the channel material in a simple back-gated configuration. To this end, we have used a high-k dielectric (Ta2O5) as the gate oxide, which is expected to reduce the voltage swing and hence the power consumption, which is beneficial when used in neuromorphic networks. The hysteresis in the transfer characteristics of the transistor arising out of the Ta2O5/MoS2 interface and interface trap charges within the oxide are exploited to demonstrate excitatory Post Synaptic current (EPSC) / Inhibitory Post Synaptic current (IPSC), Long Term Potentiation (LTP) / Long Term Depression (LTD), Spike Amplitude Dependent Plasticity (SADP), Spike Timing Dependent Plasticity (STDP) at a relatively lower energy budget. In the second part, we discuss the working mechanism of 2D ferroelectric semiconducting channel material (α-In2Se3) for synaptic applications. Ferroelectric materials have emerged as a promising candidate for enabling synaptic devices as they lead to fast operation, non-destructive readout, low-power, low variations, and high on/off ratios. The partial polarization switching behavior of the ferroelectric material can be exploited to emulate the biological synaptic functions by gradually modulating the channel conductance through an external electrical field. We also explored the continuous weight modulation through partial polarization of the channel displaying an excellent linear weight update trajectory with multiple stable conductance states. In the next part of the dissertation, we discuss artificial neural networks for pattern recognition using the conductance weights obtained from device-level emulation of synaptic dynamics. By updating the synaptic weights with conductance weight values on 18,000 digits, we achieved a successful recognition rate of 93% on the testing data. The introduction of 0.10 variance of noise pixels results in an accuracy of more than 70%, showing the strong fault-tolerant nature of the conductance states. These synaptic functionalities, learning rules, and device-to-subsystem-level simulation results based on α-In2Se3 could facilitate the development of more complex neuromorphic hardware systems based on FeS-FETs. In the last part of the dissertation, we introduce a light-sensing function merged into the artificial synapses to realize an optoelectronic synapse. The optical input signal (λ = 527 nm) is used as a presynaptic signal with various frequencies and strengths to imitate the synaptic functionalities such as short-term memory (STM) and long-term memory (LTM), paired-pulse facilitation (PPF), spike rate-dependent plasticity (SRDP) spike duration-dependent plasticity (SDDP) and memory functions like learning, forgetting, and relearning

The generation and detection of surface acoustic waves (SAWs) using interdigital transducers (IDTs) on a piezoelectric surface have been used to produce many high performance Band Pass Filters. This thesis focuses on the design and simulation of various SAW Band Pass Filters. IDTs can be fabricated on many piezoelectric substrates. The effect of substrate properties – electromechanical coupling coefficient and SAW velocity, on filter frequency response is analyzed. The IDT design properties comprise film thickness ratio, metallization ratio, acoustic aperture, and number of finger pairs. The behavior of electrical equivalent circuit of an IDT that consists of impedance parameters – radiation conductance, radiation susceptance, and capacitance, is simulated and analyzed for different piezoelectric materials. Different IDT designs offer different propagation environment to SAWs. The IDT designs based on electrode spacing – uniform and non-uniform, direction of SAW propagation – bidirectional and unidirectional, acoustic aperture – apodized and unapodized, and electrode configuration – solid electrode and split electrode, are studied. The effect of IDT design on filter performance is assessed. The design of linear phase SAW filter using fourier transform, and effect of truncation on filter specifications – amplitude ripple, side lobe rejection ratio, insertion loss, and transition bandwidth is thoroughly depicted and analyzed. The cosine window function technique is used to improve filter performance. The second order effects – bulk wave interference, diffraction, impedance matching, electromagnetic feedthrough, triple transit interference, and harmonics that corrupt the filter performance are elaborated. The effect of metallization ratio on higher harmonic suppression is studied. Design of advanced SAW band pass filters – comb filters and resulting frequency response is also explored.

Heat conduction plays a key role and is linked to the underneath lattice structure. The heat transfer in soft matter materials like DNA and polymers is seldom understood and is deeply linked to the geometry and functional groups in the molecule. Also, probing thermal conduction in shorter length scales using computations gives us a fundamental understanding of the link between structure and phenomena with respect to heat transfer. DNA satisfies the low thermal conductivity requirements for building molecular thermoelectric devices. This was a motivation for this study. Using this motivation, this thesis investigates the thermal conductivity of B-DNA and other layered materials. The thermal conductivity of B-form double-stranded DNA (dsDNA) of the Drew-Dickerson sequence d(CGCGAATTCGCG) is computed using classical Molecular Dynamics (MD) simulations. In contrast to previous studies, which focus on a simplified 1-dimensional model or a coarse-grained model of DNA to reduce simulation times, full atomistic simulations are employed to understand the thermal conduction in B-DNA. Thermal conductivity at different temperatures from 100 to 400 K are investigated using the Einstein-Green-Kubo equilibrium and Müller-Plathe non-equilibrium formalisms. The thermal conductivity of B-DNA at room temperature is found to be 1.5 W/m·K in equilibrium and 1.225 W/m·K in non-equilibrium approach. In addition, the denaturation regime of B-DNA is obtained from the variation of thermal conductivity with temperature. It agrees with previous works using Peyrard-Bishop-Dauxois (PBD) model at a temperature of around 350 K. The quantum heat capacity (Cvq ) has given the additional clues regarding the Debye and denaturation temperature of 12-bp B-DNA. Also, the effect of changing base-pairs on the thermal conductivity of dsDNA, needed investigation at a molecular level. Hence, four sequences, viz. poly(A), poly(G), poly(CG) and poly(AT) were initially analysed in this work. Firstly, length of these sequences was varied from 4-40 base-pairs (bp) at 300 K and the respective thermal conductivity (κ) was computed. Secondly, the temperature dependent thermal conductivities between 100 K and 400 K were obtained in 50 K steps at 28 bp length. The Müller-Plathe reverse non-equilibrium molecular dynamics (RNEMD) was employed to set a thermal gradient and obtain all thermal conductivities in this work. Moreover, mixed sequences using AT and CG sequences, namely A(CG)nT (n=3-7), ACGC(AT)mGCGT (m=0-5) and ACGC(AT)nAGCGT (n=1-4) were investigated based on the hypothesis that these sequences could be better thermoelectrics. 1-dimensional lattices are said to have diverging thermal conductivities at longer lengths, which violate Fourier law. These follow power law, where κ ∝ Lβ . At longer lengths, the exponent β need to satisfythe condition β > 1/3 for divergent thermal conductivity. We find no such significant Fourier law violation through divergence of thermal conductivities at 80 bp lengths or 40 bp lengths. Also, in the case of second study, the presence of short (m ≤ 2) encapsulated AT sequences within CG sequences show an increasing has given the additional clues regarding the Debye and denaturation temperature of 12-bp B-DNA. Also, the effect of changing base-pairs on the thermal conductivity of dsDNA, needed investigation at a molecular level. Hence, four sequences, viz. poly(A), poly(G), poly(CG) and poly(AT) were initially analysed in this work. Firstly, length of these sequences was varied from 4-40 base-pairs (bp) at 300 K and the respective thermal conductivity (κ) was computed. Secondly, the temperature dependent thermal conductivities between 100 K and 400 K were obtained in 50 K steps at 28 bp length. The Müller-Plathe reverse non-equilibrium molecular dynamics (RNEMD) was employed to set a thermal gradient and obtain all thermal conductivities in this work. Moreover, mixed sequences using AT and CG sequences, namely A ( CG ) n T (n=3-7), ACGC ( AT ) m GCGT (m=0-5) and ACGC ( AT ) n AGCGT (n=1-4) were investigated based on the hypothesis that these sequences could be better thermoelectrics. 1-dimensional lattices are said to have diverging thermal conductivities at longer lengths, which violate Fourier law. These follow power law, where κ ∝ Lβ . At longer lengths, the exponent β need to satisfy the condition β > 13 for divergent thermal conductivity. We find no such significant Fourier law violation through divergence of thermal conductivities at 80 bp lengths or 40 bp lengths. Also, in the case of second study, the presence of short (m ≤ 2) encapsulated AT sequences within CG sequences show an increasing trend. These results are important for engineering DNA based thermal devices. DNA and layered materials are characterized by a stacking periodicity. Whilst in DNA, we have weakly interacting base pair stacking, in layered materials we have Van der Waals interactions . Anharmonicity is strong in both materials. The phonon dispersion of an atomic layer of h-BN and the heat capacity of MAX phase Ti3SiC2 nanolaminates are calculated using ground state density functional theory (DFT) calculations. trend. These results are important for engineering DNA based thermal devices. DNA and layered materials are characterized by a stacking periodicity. Whilst in DNA, we have weakly interacting base pair stacking, in layered materials we have Van der Waals interactions . Anharmonicity is strong in both materials. The phonon dispersion of an atomic layer of h-BN and the heat capacity of MAX phase Ti3SiC2 nanolaminates are calculated using ground state density functional theory (DFT) calculations.
Ministry of Education, Government of India

Search for clean and renewable energy resources has driven recent interest in designing thermoelectric materials that convert the waste heat to useful electricity. High performance thermoelectric materials require excellent electronic transport and favorable thermal transport, simultaneously. Given the interdependence of various transport parameters, it is daunting to achieve desirable performance. We attempt to address some of these challenges using density functional theory in combination with machine-learning based approaches. We first report the decoupling of Seebeck coefficient and electrical conductivity by tuning the distortion parameter of chalcopyrites leading to complete convergence of bands, thereby resulting in unprecedented enhancement of electronic transport properties. A combination of excellent electronic transport and low thermal conductivity in CdGeAs2 results into a high ZT of 1.67 at 1000K. To find a system with low thermal conductivity, we study the oxychalcogenide system AgBiTeO, demonstrating the unique collective rattling motion hosted by chemical bond hierarchy. The favorable electronic and thermal transport properties result in a maximum ZT of 1.99 at 1200K, which is highest among the existing bulk oxide-based thermoelectric materials. Owing to the complexity and resource extensive calculations involved in determining electron relaxation time (τel), we employed machine learning approach to estimate the τel. The machine learning model uses data available for experimental electrical conductivity and a collection of accessible elemental information. This model with a rmse of 0.22, outperforms the deformation potential model, and performs adequately on the unseen data to predict the relaxation time over a wide range of temperatures. Further, we develop an effective descriptor by using chalcopyrite class of compounds, to guide an accelerated screening of materials with desirable degree of anharmonicity. The high-throughput study corroborates the role of a very simple parameter, “phonon band center”. This can be calculated within the harmonic regime, yet having profound impact on the anharmonicity of the compounds. Since, the performance of thermoelectric devices is limited by the quality of the interface, we explore the role of fundamental parameters, such as surface termination of interface, electronegativity difference and lattice mismatch that influence the interface. Optimization of these parameters will have a significant role in preserving the thermoelectric performance of the materials in devices. The results of our study pave way to overcome some of the critical challenges related to thermoelectrics by effectively addressing electronic and thermal transport problems.

The discovery of LiFePO4 cathode for Li-ion battery ushered intensive study on polyanionic high-voltage battery insertion materials. Polyanionic materials offer rich crystal chemistry, robust framework, voltage tunability, and high redox potential based on the inductive effect due to the polyanionic unit [(XO4)mn-, X = S, P, Si, W, Mo, etc.] [1]. Among them, SO4-based polyanionic systems have the advantage of higher redox potential and ease/versatility of low temperature synthesis. In this spirit, I have investigated bisulfate [A2-xM(SO4)2: A= Li, Na, K; x= 0,1] and hydroxysulfate [AMSO4OH: A = Li] type sulfate-based polyanionic frameworks. Few salient features of my thesis work are: (i) Spray drying route was used to discover a metastable monoclinic polymorph of Li2NiII(SO4)2 (s.g. P21/c). As per first principle calculations, it can work as a 5.5 V (vs. Li+/Li) cathode for Li-ion battery coupling both cationic (Ni2+/Ni3+) and anionic (O-) redox activity. The crystal chemistry, phase stability landscape and the ground state magnetic structure (A-type Antiferromagnetic spin ordering) of this novel compound have been examined [2,3]. (ii) Mineralogical exploration and synthetic preparation of naturally found minerals are strategically used to unveil battery electrode materials. Following, saranchinaite Na2Cu(SO4)2 and its hydrated derivative kröhnkite Na2Cu(SO4)2.2H2O bisulfate minerals have been prepared using the facile spray drying synthesis route. The thermodynamic phase stability landscape has been explored along with the structural effects on the Na+ ion mobility. While the presence of Cu makes them unsuitable for insertion ion chemistry, they have been reported as potential conversion type battery electrodes [4]. (iii) The eldfellite NaVIII(SO4)2 (s.g. C2/m) is demonstrated as a versatile novel cathode material for both Li-ion (2.57 V, 80 mAh/g) and Na-ion (2.28 V, 70 mAh/g) battery at current rate of C/20 and based on solid solution reaction mechanism. (iv) Hydrothermally prepared orthorhombic polymorph of FeIIISO4OH (s.g. Pnma) has been examined as a 3.2 V (110 mAh/g, C/20) Li-ion battery cathode. I have further demonstrated the first reversible Na-ion (de)insertion in monoclinic FeIIISO4OH at ~2.9 V based on solid solution reaction mechanism with a discharge capacity of 85 mAh/g (C/100) [5,6]. Overall, this work can be suitably placed in the materials science tetrahedron encompassed by “structure-property-processing-performance”. I will elaborate the above-mentioned sulfate based polyanionic battery insertion materials.
Ministry of Human Resource Development

The past years have seen an increasing interest in high-efficient thermoelectric materials because of their promising application to harvest the widely distributed waste heat. Realizing high-efficient TE materials into actual devices remains a challenge. The suitability of thermoelectric material is judged by a dimensionless parameter called thermoelectric figure-of-merit, zT. The efficiency of a thermoelectric (TE) device depends on material parameters and, to a large extent, on joints/contacts these semiconducting materials form with metallic conductors for completing an electrical circuit. The maximum power output gets significantly reduced due to parasitic losses occurring at these metal-semiconductor junctions because of many interdependent factors. One of the critical factors is the chemical interaction of TE materials with the conducting connectors like Cu, Ag, or Al. The interaction of TE materials with these materials results in intermetallic phases that deteriorate the interface properties, leading to decreased bond strength and, in severe cases, mechanical detachment of the joints. Additionally, since these devices are intended to work at higher ranges of temperatures, unwarranted growth of phases formed during joining or during operation due to atomistic diffusion of elements significantly affects these joints' reliability. A diffusion barrier is inserted between the semiconductor and metal conduct/solder alloys to prevent this interaction. The diffusion barrier, which is in immediate contact with TE material, is called the contact material for that TE. PbTe is a state-of-the-art thermoelectric alloy for power generation in intermediate-temperature range applications (600-900K) whose maximum zT values have already reached 2.2-2.5. This thesis investigates the interaction between PbTe (TE material) and Ni (and its alloys) as contact material by conducting a structural and microstructural study of temperature-dependent phase evolution at diffusion bonded interfaces. The thesis is divided into seven chapters.

The monograph is devoted to the creation of a single complex of scientiJic and practical developments aimed at solving the problems of knowledge operation (such as information or data) by means of their graphic structuring and representation (GSR) in any subject areas of science and practice. In particular, it can be used in information and digital technologies, knowledge engineering, systemic analysis, cognitive science, implementation of interdisciplinary research, etc. Its main purpose is systematization of knowledge, as well as conceptual modeling of complex notions and objects of activity in the logic of problem-oriented approach. The complex is a trinity of theoretical principles, graphic language of conceptual modeling (GLCM) of knowledge, and the GSR technology, implemented using Microsoft Excel, and has no analogues in the given subject area. Its basis is Linkov’s diagonal information graphic knowledge matrix (digmata), being a universal way to extract and structure knowledge from text and other sources, as well as a universal converter of any representation form of knowledge into a uniform graphic form. Simplicity and constructiveness of the complex allow its wide introduction into practice. The monograph is accompanied by a USB Jlash drive containing text and graphic materials. The monograph is intended for the widest range of persons confronted with the above-mentioned problems of science and practice.

This contribution introduces an innovative model of assessment and validity of the formal-dimensional-functional structure for passenger seats in economy class in the Aerospace industry. In fact in this field, the design, ergonomics and engineering determine unpublished cooperation scenarios where roles are inverted, merge and recur repeatedly, in order to establish progress in the different planning and subject areas, having a synergistic and proactive perspective. The research activities have been developed within the framework of there search project “IMM_Interiors with Multifunctional Materials_DAC_Distretto Aerospaziale Campania” (Campania Aerospace District), in which experts from different branches of knowledge such as designers, innovative materials engineers, mechanical engineers, biologists and technical physicists from the Second University of Naples were involved. The use of new methodological dimensions resulted in the identification of common activity protocols, which were used as foundations in the planning stage, interdisciplinary and shared. The aim was to obtain a passenger seat configuration suitable to meet the demands and needs of the greatest number of individuals, according to their specifications and through the integration of innovative technologies and materials. The impact of different cultural factors, the mixture of roles and subjects, the layering of competences and heterogeneous and contradictory operational references have contributed towards a shared narrative where knowledge and experience have established the key principles in the course of evaluation and validity (methodological-designing inclusive). This route has allowed the acquisition of interdisciplinary skills and expertise qualified to obtain tangible results from the identification of methodological and design issues useful to optimize, innovate and streng then the design process. The goal was to make the acquisition of user needs systematic, through investigation and evaluation methods aimed at translating them into a structured format noted on the design process according to the principles of good design. In particular studies and research of prior art patents and thorough investigation literature regarding the state of the art of existing seat configurations and structures were carried out. Feasibility, comfort and reliability of the existing solutions in order to analyse and evaluate each component of ergonomics, human factors (physical ergonomics), user centred design and new human factors (pleasantness of use), where characteristics and specific meanings of quality, understood as a user-seat interaction quality are preferred.DOI: http://dx.doi.org/10.4995/IFDP.2016.3296