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Molecular spintronics devices (MSDs) attempt to harness molecules’ quantum state, size, and configurable attributes for application in computer devices—a quest that began more than 70 years ago. In the vast number of theoretical studies and limited experimental attempts, MSDs have been found to be suitable for application in memory devices and futuristic quantum computers. MSDs have recently also exhibited intriguing spin photovoltaic-like phenomena, signaling their potential application in cost-effective and novel solar cell technologies. The molecular spintronics field’s major challenge is the lack of mass-fabrication methods producing robust magnetic molecule connections with magnetic electrodes of different anisotropies. Another main challenge is the limitations of conventional theoretical methods for understanding experimental results and designing new devices. Magnetic tunnel junction-based molecular spintronics devices (MTJMSDs) are designed by covalently connecting paramagnetic molecules across an insulating tunneling barrier. The insulating tunneling barrier serves as a mechanical spacer between two ferromagnetic (FM) electrodes of tailorable magnetic anisotropies to allow molecules to undergo many intriguing phenomena. Our experimental studies showed that the paramagnetic molecules could produce strong antiferromagnetic coupling between two FM electrodes, leading to a dramatic large-scale impact on the magnetic electrode itself. Recently, we showed that the Monte Carlo Simulation (MCS) was effective in providing plausible insights into the observation of unusual magnetic domains based on the role of single easy-axis magnetic anisotropy. Here, we experimentally show that the response of a paramagnetic molecule is dramatically different when connected to FM electrodes of different easy-axis anisotropies. Motivated by our experimental studies, here, we report on an MCS study investigating the impact of the simultaneous presence of two easy-axis anisotropies on MTJMSD equilibrium properties. In-plane easy-axis anisotropy produced multiple magnetic phases of opposite spins. The multiple magnetic phases vanished at higher thermal energy, but the MTJMSD still maintained a higher magnetic moment because of anisotropy. The out-of-plane easy-axis anisotropy caused a dominant magnetic phase in the FM electrode rather than multiple magnetic phases. The simultaneous application of equal-magnitude in-plane and out-of-plane easy-axis anisotropies on the same electrode negated the anisotropy effect. Our experimental and MCS study provides insights for designing and understanding new spintronics-based devices.

Aspiring graduate students in science and technology generally lack formal training in understanding human behavior and traits that can adversely impact their ability to perform and innovate at the highest level. Positive intelligence (PI) and Transactional Analysis are two practical methods in human psychology that millions of people have tested for self-growth. The author previously published the application of PI for enhancing engineering students (Tyagi, P., Positive Intelligence Education for Unleashing Student Potential. ASME 2019 International Mechanical Engineering Congress and Exposition 2019, Volume 5: Engineering Education, V005T07A009). This paper focuses on training graduate students about the popular and practical transactional analysis science and assessing their competence in utilizing this knowledge to decipher their own and other people’s. Transactional analysis was taught to students via Student presentation-based effective teaching (SPET) methodology developed by the author. Under this approach, graduate students enrolled in the MECH 500 Class were provided a set of questions to answer by self-reading of the recommended textbook “I am Okay You are Okay by Thomas Harris”. Each student individually answered the assignment questions and then worked in the group to prepare a group presentation for the in-class discussion. Three group discussions were conducted to present different views about the four types of transactions and underlying human traits. Before transactional analysis training, students were also trained in Positive intelligence psychology tools for a similar objective. After the discussion, students were surveyed about the depth of their understanding. Students also reflected their views on the utility of transactional analysis with respect to positive intelligence. More than 75% of students mention that they gain high competency in understanding, defining, and utilizing transactional analysis. This study presents insights for positively impacting graduate students’ mindsets as they pursue an unpredicted course of research that can sometimes become very challenging.

Existing additive manufacturing (AM) technologies produce metal components with a rough surface that generally display fatigue characteristics, leading to component failure and undesirable friction coefficients to the printed part. Small cracks formed at regions of high surface roughness in rough surfaces act as a stress raiser or crack nucleation site. Hence, as-produced parts’ direct use is limited and introduces a challenge related to smoothening the surface. The present study explores the application of electroless nickel deposition. It examines the surface finishing techniques such as Chempolishing (CP) and Electropolishing (EP) for post-processing on additively manufactured stainless-steel samples. Previous studies have demonstrated that CP offers a major advantage in providing consistent, smooth surfaces, regardless of the component size or geometry. Surface smoothness is increased, and surface roughness is decreased to the sub-micrometer range via EP. The study also investigates nickel deposition on EP, CP, and as-built AM components, utilizing electroless nickel solutions. Alloys are exposed to an electroless nickel plating process in order to enhance the hardness and surface resistance of produced components to the hostile environment. The medium-phosphorus (6–9% P), and high-phosphorus (10–13% P) was used. The Ni deposition experiments were optimized using the L9 Taguchi design of experiments (DOE), which involve the prosperous content in the solution, surface preparation, plane orientation of the sample geometry, and Nickel strike exposition time. The pre- and post-processed surface of the AM parts is being investigated by the KEYENCE Digital Microscope VHX-7000. This work is in progress concerning the complete Scratch analysis and Design of Experiment (DOE) analysis using the Qualitek-4 software.

Engineering Research Innovation Commercialization (ERIC) seeks to translate products or services from the research laboratory to the marketplace or the end-user for societal benefit. Research indicates that universities have distinctive capabilities that allow them to play an important role in the process of research innovation commercialization. Historically Black Colleges and Universities (HBCUs), though originally established mainly as teaching and blue-collar trade institutions to educate African Americans, have been gradually commercializing several research innovations through patenting. However, this is significantly lower compared to that of their counterparts (specifically, Predominately White Institutions – PWIs). This according to available research is mainly because HBCUs have been traditionally under-served and under-resourced. Currently several programs such as the National Science Foundation (NSF) I-Corps and National Science Foundation Center of Research Excellence in Science and Technology (NSF-CREST) Center for Nanotechnology Research and Education (CNRE)) are being implemented by HBCUs to promote the commercialization of research innovations by training innovators about commercializing innovations. However, little research has been done to assess the level of awareness of engineering undergraduate students at an HBCU about the commercialization of engineering research innovations. This pilot study, therefore, seeks to investigate the level of awareness of engineering undergraduate students at an HBCU about engineering research innovation commercialization. The authors of this study have conducted a similar study that focused only on engineering graduate students in an HBCU. To achieve the purpose of this study, we developed a survey that adopts both binary and ordinal scales of question and administered it to 30 engineering undergraduate students in an ABET-accredited HBCU. After collation and analysis, the results indicate a low level of awareness of engineering research innovation commercialization by engineering undergraduate students at this University. Though at a pilot stage (to be validated by a larger study in different HBCUs), the study recommends that HBCUs initiate new or strengthen ongoing innovation commercialization training programs by including it in undergraduate engineering first-year courses such as “Introduction to Engineering” and related courses to help students become more aware of the opportunities in engineering research innovation commercialization processes.

Previous research has indicated the importance of effective communication in globalization as individuals from different countries, languages, cultural inclinations, and other background variations need to understand one another and express themselves to work effectively together. Our ability to interact with others productively during our adulthood has been linked to what happened in our early childhood. Of particular importance to effective interaction is the study by Dr. Eric Berne, a psychologist, who developed the term Transactional Analysis (TA) in the 1950 and the 60s. Transactional analysis is defined by the International Transactional Analysis Association as a theory of personality and a systematic psychotherapy for personal growth and personal change. Dr. Berne postulated that adulthood reactions to situations are largely determined by the treatment received from main caregivers during early childhood (that is birth to 5 years). As part of his theory of personality, he identified three ego-states known as Parent (P), Adult (A), and Child (C). Over the years, Dr. Berne’s theory has been applied in varied fields such as counseling, psychotherapy, organizational development, and education, and various studies have assessed its effectiveness in a wide variety of contexts. However, little research has been done to develop engineering students’ potential for effective communication to promote the globalization of engineering, after being taught TA using Student Presentation Based Effective Teaching (SPET). This study seeks to promote the globalization of engineering by developing students’ potential for productive communication using Transactional Analysis. To achieve this, we developed a Transactional Analysis Tool to evaluate the communication traits of engineering students taught TA through SPET in the MECH 500 Research Experience and Technical Communication (RETC) course and that of a control group, who were not taught TA. The results indicate engineering students introduced to TA, have a high level of self-awareness to effectively communicate globally when compared with that of the control group. We believe that to promote the globalization of engineering, it is important that engineering students’ productive communication competencies are developed through concepts such as TA and Positive Intelligence, by including these in universities’ engineering curricula.

Additively Manufactured (AM) components' surface finishing is crucial in adopting them for intended applications in challenging environments involving fatigue, corrosion, high temperature, and nuclear radiation. In our prior research, chempolishing(C) was utilized as an electroless etching process that uniformly smoothens complex AM components' accessible interior and exterior surfaces(Tyagi et al., Additive Manufacturing, Vol.25 pp.32). A wide range of electropolishing(E) has been demonstrated for AM surface finishing. However, electropolishing can impact a surface that can be juxtaposed to counter electrode and can a very smooth surface to sub-micrometer level roughness. However, a knowledge gap exists about the impact of applying both approaches on the same surface one after another and what new advantages may arise because of combining two methods. This paper uses dual-stage liquid-based surface finishing strategies produced by alternating the chempolishing(C) and electropolishing(E) steps. Two dual-stage surface finishing approaches, i.e., chempolishing followed by electropolishing(CE) and electropolishing followed by chempolishing (EC), were performed on the 316 stainless AM steel component. Impacts of EC and CE approaches were compared with single-stage C and E surface finishing approaches. An optical microscope and mechanical profilometer were utilized to investigate the wide range of surface roughness parameters. CE and EC produced Ra ~ 1.4 µm and ~ 1.6 µm, respectively. Surface roughness on CE and EC treated AM samples was lower than those individually treated by C and E approaches. Scanning electron microscopy provided further insights into the microstructural difference between CE and EC treated AM samples. This paper reports a liquid contact angle study on CE and EC treated AM samples to provide insights into the relative difference in surface energy that is crucial for making coatings on AM parts. A spectroscopic reflectance study was also employed to register the difference in physical properties of AM components treated with CE, and EC approaches. This study reveals industrially practicable interior and exterior surface finishing approaches for complex AM metal components that require minimum tooling and real-time process monitoring.

To rescue the future from the global energy crisis and to ensure it with clean and economical hydrogen energy, it is an urgency to develop an efficient OER catalyst, which intensely sluggish the kinetic process of hydrogen production. Herein, we have precisely synthesized an efficient, stable, earth-abundant metal-based NiFe2O4/rGO hybrid OER electrocatalysts by a simple solvothermal method. The measurements including XRD, FTIR, XPS, EDS, SEM, and TEM revealed the prominent structural integrity of catalyst with crystal-layered structure. The rich oxidation chemistry of transition metals and substantially active carbon substrate allows tuning of their electronic properties concerning their concentration, composition, and morphology. The effect of different Ni wt.% (0%, 2%, 4%, and 6%) on the morphology of hybrid as well as on electrochemical performance investigated. The protocols like overpotential required to achieve a current density of 10 mA/cm2, Tafel slope, ECSA, RF, EIS, stability was utilized to examine the overall abilities of electrocatalyst in alkaline 1 M KOH solution. The optimized NiFe2O4/rGO hybrid with 2 wt % Ni exhibited the excellent OER performance, which delivers a current density of 10 mA/cm2 at an overpotential of only 302 mV with a small Tafel slope of 63 mV/dec. The high activity of the catalyst is attributed to the synergistic effect of the crystal-layered structure as well as rapid mass-charge transfer. Such, rational design concept of anchoring non-precious metal on carbon in a controlled manner, offering splendid flexibility to tailor electrochemical OER performance. The optimized variations in metal concentration and morphologies, providing a promising route to develop a cost-effective catalyst for advanced energy conversion applications.

Paramagnetic single-molecule magnets (SMMs) interacting with the ferromagnetic electrodes of a magnetic tunnel junction (MTJ) produce a new system. The properties and future scope of new systems differ dramatically from the properties of isolated molecules and ferromagnets. However, it is unknown how far deep in the ferromagnetic electrode the impact of the paramagnetic molecule and ferromagnet interactions can travel for various levels of molecular spin states. Our prior experimental studies showed two types of paramagnetic SMMs, the hexanuclear Mn6 and octanuclear Fe–Ni molecular complexes, covalently bonded to ferromagnets produced unprecedented strong antiferromagnetic coupling between two ferromagnets at room temperature leading to a number of intriguing observations (P. Tyagi, et al., Org. Electron., 2019, 64, 188–194. P. Tyagi, et al., RSC Adv., 2020, 10, (22), 13006–13015). This paper reports a Monte Carlo Simulations (MCS) study focusing on the impact of the molecular spin state on a cross junction shaped MTJ based molecular spintronics device (MTJMSD). Our MCS study focused on the Heisenberg model of MTJMSD and investigated the impact of various molecular coupling strengths, thermal energy, and molecular spin states. To gauge the impact of the molecular spin state on the region of ferromagnetic electrodes, we examined the spatial distribution of molecule-ferromagnet correlated phases. Our MCS study shows that under a strong coupling regime, the molecular spin state should be ∼30% of the ferromagnetic electrode's atomic spins to create long-range correlated phases.

This study investigates the application of electroless nickel deposition on additively manufactured stainless steel samples. Current additive manufacturing (AM) technologies produce metal components with a rough surface. Rough surfaces generally exhibit fatigue characteristics, increasing the probability of initiating a crack or fracture to the printed part. For this reason, the direct use of as-produced parts in a finished product cannot be actualized, which presents a challenge. Post-processing of the AM parts is therefore required to smoothen the surface. This study analyzes chempolish (CP) and electropolish (EP) surface finishing techniques for post-processing AM stainless steel components CP has a great advantage in creating uniform, smooth surfaces regardless of size or part geometry EP creates an extremely smooth surface, which reduces the surface roughness to the sub-micrometer level. In this study, we also investigate nickel deposition on EP, CP, and as-built AM components using electroless nickel solutions. Electroless nickel plating is a method of alloy treatment designed to increase manufactured component’s hardness and surface resistance to the unrelenting environment. The electroless nickel plating process is more straightforward than its counterpart electroplating. We use low-phosphorus (2–5% P), medium-phosphorus (6–9% P), and high-phosphorus (10–13% P). These Ni deposition experiments were optimized using the L9 Taguchi design of experiments (TDOE), which compromises the prosperous content in the solution, surface finish, plane of the geometry, and bath temperature. The pre- and post-processed surface of the AM parts was characterized by KEYENCE Digital MicroscopeVHX-7000 and Phenom XL Desktop SEM. The experimental results show that electroless nickel deposition produces uniform Ni coating on the additively manufactured components up to 20 μm per hour. Mechanical properties of as-built and Ni coated AM samples were analyzed by applying a standard 10 N scratch test. Nickel coated AM samples were up to two times scratch resistant compared to the as-built samples. This study suggests electroless nickel plating is a robust viable option for surface hardening and finishing AM components for various applications and operating conditions.

National Science Foundation funding was obtained to nucleate nanotechnology curriculum and start a senior-level nanotechnology course cross-listed in the Mechanical Engineering and Electrical Engineering department. The key components are implementation of lectures integrated with hands-on laboratory experience, research seminar and evaluation. Laboratory projects of nanofabrication include metal-oxide-semiconductor capacitor and nano-structured solar cell for undergraduate and graduate students respectively. The assessment of course materials and master’s understanding was evaluated by surveys and direct observations of student performance. In spring 2020, statistical data from survey demonstrated that graduate students responded overall high rate for all of the course materials and undergraduate students gave high rate for majority of course materials except thermal evaporation fabrication project. A significant standard deviation for rating of thermal evaporation fabrication process indicated that practical engineering projects are challenging for some undergraduate students.

The hydrogen-based economy is gaining momentum with the advent of fuel cell electric cars and other systems. Hence hydrogen production becomes critically important to meet a supply demand in the near future. One of the cheapest hydrogen generation sources can be solar energy and seawater or water in the lakes and rivers. One can utilize solar energy to provide electricity or energy for the photocatalytic process to split water into hydrogen and oxygen. Under electrolysis, electricity is supplied to provide the energy required for water splitting converting hydrogen ions into hydrogen gas from the aqueous medium. There is a strong need to create innovative electrodes for hydrogen generation that are economical in production and highly efficient. To address this issue, we focused on designing electrodes for photocatalytic electrolysis for hydrogen generation. We used 3D printing to produce different electrodes with various surface features to provide optimum surface area and used electroless nickel to coat the surface of the 3D printed metal components. It is noteworthy that nickel is a promising metal to produce hydrogen economically. We used the Taguchi Design of Experiment approach to optimize the nickel coating on the 3D printed metal electrodes. We used cyclic voltammetry to quantify the volume of H2 produced by the nickel-coated 3D printed electrodes.

Historically Black Colleges and Universities (HBCUs) innovators lag behind their non-HBCU counterparts in the commercialization of innovations as they were originally set up as teaching and blue-collar trade institutions. There exists a strong need for education and training to bridge this gap by promoting the commercialization of innovations in HBCUs and thus transform next-generation HBCU innovators into entrepreneurs. HBCUs are promoting entrepreneurial education and mindset via changes in engineering education programs and curriculums. Several federally funded programs like the National Science Foundation (NSF) Center of Research Excellence in Science and Technology (CREST) Center for Nanotechnology Research Excellence (CNRE) are promoting innovation and intellectual property generation at HBCUs. NSF I-Corps Program supports the education and training of innovators about the commercialization of mature or patented innovations at HBCUs. The NSF I-Corps Introduction to Customer Discovery explores strategies in identifying key customer segments through extensive customer interviews, which is a fundamental step in the commercialization process. This paper discusses our educational experience in the customer discovery process for Pumpless Solar Thermal Air Heater (Patent Number 10775058). To learn about prospective customers’ attitudes and perceptions of the innovation, we conducted 30 interviews with potential customers (end users). Our innovation is focused on providing portable, cost-effective, healthy, and environmentally friendly space heating solutions. We tested several hypotheses about the value proposition of our innovation during interviews to explore the market segments for potential commercialization. During the Customer Discovery process, we came to know about new issues such as health issues caused by the dry air in winter. We also learned that mitigation of problems due to the current heating system required a humidifier to reduce health issues that added additional cost. Based on our interviews our innovation is suitable for customers needing: (i) Heating source mitigating health issues, (ii) add-on technology to reduce their heating bills. Our next step is to pursue market segments for our innovation. We plan to utilize the current experience of commercialization of intellectual property to develop training modules for the MECH 302 Undergraduate Research Experience and MECH 500 Research Methods and Technical Communication courses offered under the mechanical engineering program at the University of the District of Columbia (UDC).

Inorganic crystalline silicon solar cells account for more than 90% of the market despite a recent surge in research efforts to develop new architectures and materials such as organics and perovskites. The reason why most commercial solar cells are using crystalline silicon as the absorber layer include long-term stability, the abundance of silicone, relatively low manufacturing costs, ability for doping by other elements, and native oxide passivation layer. However, the indirect band gap nature of crystalline silicon makes it a poor light emitter, limiting its solar conversion efficiency. For instance, compared to the extraordinary high light absorption coefficient of perovskites, silicon requires 1000 times more material to absorb the same amount of sunlight. In order to reduce the cost per watt and improve watt per gram utilization of future generations of solar cells, reducing the active absorber thickness is a key design requirement. This is where novel two-dimensional (2d) materials like graphene, MoS2 come into play because they could lead to thinner, lightweight and flexible solar cells. In this chapter, we aim to follow up on the most important and novel developments that have been recently reported on solar cells. Section-2 is devoted to the properties, synthesis techniques of different 2d materials like graphene, TMDs, and perovskites. In the next section-3, various types of photovoltaic cells, 2d Schottky, 2d homojunction, and 2d heterojunction have been described. Systematic development to enhance the PCE with recent techniques has been discussed in section-4. Also, 2d Ruddlesden-Popper perovskite explained briefly. New developments in the field of the solar cell via upconversion and downconversion processes are illustrated and described in section-5. The next section is dedicated to the recent developments and challenges in the fabrication of 2d photovoltaic cells, additionally with various applications. Finally, we will also address future directions yet to be explored for enhancing the performance of solar cells.

Magnetic tunnel junction-based molecular spintronics device (MTJMSD) may enable novel magnetic metamaterials by chemically bonding magnetic molecules and ferromagnets (FM) with a vast range of magnetic anisotropy. MTJMSD have experimentally shown intriguing microscopic phenomenon such as the development of highly contrasting magnetic phases on a ferromagnetic electrode at room temperature. This paper focuses on Monte Carlo Simulations (MCS) on MTJMSD to understand the potential mechanism and explore fundamental knowledge about the impact of magnetic anisotropy. The selection of MCS is based on our prior study showing the potential of MCS in explaining experimental results (Tyagi et al. in Nanotechnology 26:305602, 2015). In this paper, MCS is carried out on the 3D Heisenberg model of cross-junction-shaped MTJMSDs. Our research represents the experimentally studied cross-junction-shaped MTJMSD where paramagnetic molecules are covalently bonded between two FM electrodes along the exposed side edges of the magnetic tunnel junction (MTJ). We have studied atomistic MTJMSDs properties by simulating a wide range of easy-axis anisotropy for the case of experimentally observed predominant molecule-induced strong antiferromagnetic coupling. Our study focused on understanding the effect of anisotropy of the FM electrodes on the overall MTJMSDs at various temperatures. This study shows that the multiple domains of opposite spins start to appear on an FM electrode as the easy-axis anisotropy increases. Interestingly, MCS results resembled the experimentally observed highly contrasted magnetic zones on the ferromagnetic electrodes of MTJMSD. The magnetic phases with starkly different spins were observed around the molecular junction on the FM electrode with high anisotropy.

A device architecture utilizing a single-molecule magnet (SMM) as a device element between two ferromagnetic electrodes may open vast opportunities to create novel molecular spintronics devices. Here, we report a method of connecting an SMM to the ferromagnetic electrodes. We utilized a nickel (Ni)–AlOx–Ni magnetic tunnel junction (MTJ) with the exposed side edges as a test bed. In the present work, we utilized an SMM with a hexanuclear [Mn6(μ3-O)2(H2N-sao)6(6-atha)2(EtOH)6] [H2N-saoH = salicylamidoxime, 6-atha = 6-acetylthiohexanoate] complex that is attached to alkane tethers terminated with thiols. These Mn-based molecules were electrochemically bonded between the two Ni electrodes of an exposed-edge tunnel junction, which was produced by the lift-off method. The SMM-treated MTJ exhibited current enhancement and transitory current suppression at room temperature. Monte Carlo simulation was utilized to understand the transport properties of our molecular spintronics device.

The efficiency of a Si-HIT (heterojunction with intrinsic thin layer) solar cell based on a graphene/MoS2 heterostructure has been optimized by varying the various parameters of graphene (Gr) as a transparent conducting electrode (TCE) and n-type molybdenum disulfide (n-MoS2) as an emitter layer. The photovoltaic performance of a graphene/n-MoS2/a-Si:H/p-cSi/Au single facial HIT solar cell has been studied using AFORS-HET v2.5 simulation software. A maximum output efficiency of 25.61% has been achieved. The obtained results were compared with the results from a commercially available a-Si:H layer and p-cSi wafer after simulation. Moreover, the dependence of the cell performance on changes in the TCE and the back contact materials has also been studied. Finally, it has been demonstrated that the graphene layer and n-MoS2 layer could act as a TCE and an efficient emitter layer, respectively, in a n-MoS2/p-cSi based HIT solar cell.

Improving surface finishing is the critical step in the application of an additively manufactured (AM) component in high fatigue and corrosion-sensitive fields. This paper provides insights into surface properties of electropolished AM component made up of 316 stainless steel with > 6% carbon. We performed surface analysis with profilometer, scanning electron microscope, and AFM to investigate the electropolished and unpolished AM components. The first major discovery of the present work is that our optical profilometry study provided an estimate of the amount of material to be removed to achieve a shiny and smooth surface on 316 stainless steel AM part. One needs to remove more than 200 μm thick layer from the surface to make a mirror-smooth surface. Such estimation can enable researchers to incorporate requisite tolerance during the design stage itself. The second important finding of our work is that ultrasmooth microstructure on the AM surface appeared when preferential material removal occurred along the boundary of the hexagonal microscopic features. Additionally, our optical profilometry studies provided an analysis of several roughness parameters on the electropolished surface. Electropolishing was effective in reducing the surface roughness below ~ 0.1 μm RMS over microscopic regions. Observation of sub-μm RMS roughness was consistently observed with the optical profilometer, SEM, and AFM. SEM study revealed a significant change in the microstructure of the electropolished samples in a medium and highly smooth state. We also conducted a water contact angle study and spectroscopic reflectance study on electropolished and unpolished AM component surfaces. Our study revealed that electropolishing is a highly promising route for improving the surface finishing of AM components.

The hysteresis loop investigations of different size magnetic tunnel junction molecular spintronics devices (MTJMSD) have been done by Monte Carlo simulation (MCS). We employed a continuous MCS algorithm to investigate single-molecule magnet SMM's spin state's impact as a function of molecular exchange coupling strength. The applied magnetic fields were ramped at a variety of ranges of increments, unfolding physics behind the magnetization nature of each MTJMSD. The magnetic moment changes with applied magnetic fields exhibit the characteristics of devices being studied. The MTJMSDs were studied for ferromagnetic and antiferromagnetic exchange couplings. The magnetic moment saturation, retentivity, coercivity, and permeability are studied.

Striking advancement of science over the last few decades has doubled the need of having faster and more efficient electronic devices. Magnetic tunnel junction-based molecular spintronic devices (MTJMSDs) are potential platforms for futuristic computers and may significantly reduce power consumption and enhance processing speed [1], [2]. Using transport properties of electrons, MTJMSD creates conductive molecular channels between two FM electrodes (FMEs). In our previous work, we investigated the effect of several factors on MTJMSDs' magnetic properties through Monte Carlo Simulation (MCS). Our results showed that i) Molecule-FMEs' coupling strength and nature ii) FMEs' length and thickness and iii) thermal energy have determinative effect on MTJMSD magnetic behavior [3]. For our initial comprehension, we constrained our earlier studies to just electrons' transport properties via molecular channels. In this research we took one step further towards realization of MTJMSD magnetic properties and investigated the effect of spin fluctuation (SF) as well. Here, we report the result of an extreme case where molecules made a strong antiFM coupling with one electrode and a strong FM coupling with another one at room temperature (KT=0.1 of the Curie temperature) for a fixed device size. Our preliminary results show that MTJMSD's need more iteration counts to attain equilibrium state in the presence of SFs. According to our MCS results, 16 molecules can induce antiFM coupling between FMEs in both with and without SF cases. However, the spatial orientation of M is noisier in the presence of SF despite doing 500 million simulation counts. The correlation results agree with spatial orientation of electrodes and molecules' magnetic moment. Based on our observation, there is a strong negative/antiferromagnetic correlation between FMEs when there is no SF. However, there are multiple pockets of average to high negative correlation between FMEs and molecules while applying SF effect. To complement our study and gain a better understanding of the role of SF on MTJMSD's magnetic properties, we will also investigate time evolution of energy, magnetic susceptibility and coupling energy required for transition from low to high magnetization.

This project explores the impacts that temperature and various geometries have on head loss in a heat exchanger intended to be used as a component of a pumpless solar thermal heater. The heat exchanger component of the pumpless solar thermal heater is a vertical pipe configuration with one inlet pipe through which water flows downward to a well. There are a number of outlet pipes through which water flows upward from the well. The outlet pipes contain a number of conical features at some angle that act as fins to increase heat transfer. The entire heat exchanger is assumed to be submersed in a shell at constant temperature. A Python program was developed using the NTU method to calculate the temperature variation from the inlet to the outlet of the heat exchanger across a varied set of geometry parameters, including: number of outlet pipes, outlet pipe diameter, number of conical features, and angle of conical features. The impact of the temperature variation was accounted for in the head loss calculation within the Python program. For a set of head loss values, an optimized set of geometry parameters was found to maximize the outlet temperature.

Harnessing the exotic properties of molecular level nanostructures to produce novel sensors, metamaterials, and futuristic computer devices can be technologically transformative. In addition, connecting the molecular nanostructures to ferromagnetic electrodes bring the unprecedented opportunity of making spin property based molecular devices. We have demonstrated that magnetic tunnel junction based molecular spintronics device (MTJMSD) approach to address numerous technological hurdles that have been inhibiting this field for decades (P. Tyagi, J. Mater. Chem., Vol. 21, 4733). MTJMSD approach is based on producing a capacitor like a testbed where two metal electrodes are separated by an ultrathin insulator and subsequently bridging the molecule nanostructure across the insulator to transform a capacitor into a molecular device. Our prior work showed that MTJMSDs produced extremely intriguing phenomenon such as room temperature current suppression by six orders, spin photovoltaic effect, and evolution of new forms of magnetic metamaterials arising due to the interaction of the magnetic a molecule with two ferromagnetic thin films. However, making robust and reproducible electrical connections with exotic molecules with ferromagnetic electrodes is full of challenges and requires attention to MTJMSD structural stability. This paper focuses on MTJMSD stability by describing the overall fabrication protocol and the associated potential threat to reliability. MTJMSD is based on microfabrication methods such as (a) photolithography for patterning the ferromagnetic electrodes, (b) sputtering of metallic thin films and insulator, and (c) at the end electrochemical process for bridging the molecules between two ferromagnetic films separated by ∼ 2nm insulating gap. For the successful MTJMSD fabrication, the selection of ferromagnetic metal electrodes and thickness was found to be a deterministic factor in designing the photolithography, thin film deposition strategy, and molecular bridging process. We mainly used isotropic NiFe soft magnetic material and anisotropic Cobalt (Co) with significant magnetic hardness. We found Co was susceptible to chemical etching when directly exposed to photoresist developer and aged molecular solution. However, NiFe was very stable against the chemicals we used in the MTJMSD fabrication. As compared to NiFe, the Co films with > 10nm thickness were susceptible to mechanical stress-induced nanoscale deformities. However, cobalt was essential to produce (a) low leakage current before transforming the capacitor from the magnetic tunnel junction into molecular devices and (b) tailoring the magnetic properties of the ferromagnetic electrodes. This paper describes our overall MTJMSD fabrication scheme and process optimization to overcome various challenges to produce stable and reliable MTJMSDs. We also discuss the role of mechanical stresses arising during the sputtering of the ultrathin insulator and how to overcome that challenge by optimizing the insulator growth process. This paper will benefit researchers striving to make nanoscale spintronics devices for solving grand challenges in developing advanced sensors, magnetic metamaterials, and computer devices.

Student presentation based effective teaching (SPET) approach was designed to engage students with different mindsets and academic preparation levels meaningfully and meet several ABET student learning outcomes. SPET method requires that students prepare themselves by guided self-study before coming to the class and make presentations to teach the whole class by (a) presenting complex concepts and systems appealingly and engagingly, and most importantly (b) serving as the discussion platform for the instructor to emphasize on complex concepts from multiple angles during different presentations. In class, SPET presentations address the conceptual questions that are assigned 1–2 weeks before the presentation day. However, the SPET approach becomes impractical for large class sizes because (i) during one class period all the students can not present, (ii) many students do not make their sincere efforts. This paper focuses on the second modification of SPET to make it practical for large classes. The method reported in this paper was tested on MECH 462 Design of Energy System Course. Unlike the first modified approach, all the students were expected to submit the response to the preassigned questions before coming to the class. In class, SPET group presentations were prepared by the group of 3–6 students, who prepared themselves by doing SPET conceptual questions individually. Students communicated with each other to make a cohesive presentation for ∼30 min. In two classes per week, we covered 5–6 group presentations to do enough discussions and repetition of the core concepts for a more in-depth understanding of the content. During the presentation, each student was evaluated for (a) their depth of understanding, (b) understanding other parts of the presentation covered by other teammates, and (c) quality of presentation and content. The student who appeared unprepared in the class group presentation were provided direct feedback and resources to address concerning areas. SPET approach was applied in the online mode during the campus shut down due to COVID-19. SPET was immensely effective and helped to complete the course learning outcomes without interruptions. SPET could be customized for the online version without any additional preparation on the instructor part.

The surface roughness of as produced additively manufactured (AM) components is very high and may lead to component failure and undesirable coefficients of friction. In rough surfaces, small cracks form at regions of high surface roughness acting as a stress raiser or crack nucleation sites. Likewise, rough surfaces impact both static and kinetic friction that can impede desired motion and oppose desired mechanical forces. For using these components in many applications, it is necessary to reduce surface deviations drastically during postprocessing. For parts with complex geometries and enormous internal surface areas, this reduction presents a complex engineering problem. We have explored chempolishing (C) and electropolishing (E) to reduce the external and internal surface roughness of stainless-steel components in our previous studies. Chempolishing is an electroless etching process that can uniformly smoothen the accessible surfaces of complex AM components. Electropolishing can produce an extremely smooth surface to sub-micrometer level roughness. Our prior work showed that chempolishing and electropolishing produced very distinct surface microstructures. It is quite possible that in future surface finishing, chempolishing and electropolishing may be applied on the same AM component to reduce the surface roughness of complex AM components. The resulting microstructure after the sequential application of chempolishing and electropolishing may be quite different as compared to that of after chempolishing or electropolishing alone. Here, we report the application of altering the sequence of chempolishing and electropolishing to reduce the external and internal surface roughness of 316 steel components. It is unknown what will be the impact of manipulating the sequence of electropolishing and chemical polishing on surface roughness and microstructure of AM materials. This paper focuses on the post-process sequencing of chempolishing, followed by electropolishing (CE) and vice versa (EC). We found chempolishing followed by electropolishing reduced internal surface roughness by as much as 12 micrometers. Whereas the electropolishing followed by chempolishing reduced external surface roughness by an average of ∼15 micrometers. The structure and properties of the surface finished pieces were examined using: Scanning Electron Microscopy (SEM), Surface Profilometry, and Water Contact Angle Measurement. SEM provided direct insight that CE and EC process produced significantly different microstructures from each other and also from chempolished and electropolished processes. Water contact angle measurements performed on CE, and EC treated AM samples showed that surface energy was quite different. Hence, CE and EC are expected to perform quite differently under a corrosive environment and also yield various adhesion quality for the protective coatings. Confirmation of structural changes provided in this experiment shed light on the capabilities of postprocessing improvements we can make to materials performance.

Positive intelligence (PI) training can produce a transformative impact on college students. PI, a branch of human psychology, provides a tool to identify significant compulsive habits that can inhibit students’ learning potential and ability to understand others. This paper discusses the two training methods adopted for teaching graduate and undergraduate students. It is considered that including such training is fundamentally crucial for developing 21st century STEM workforce with a well-rounded personality. However, PI training may consume a significant class time allocated for covering course contents under the degree-specific curriculums. Starting a new course may increase the credit overload beyond the approved BS and graduate credits. This paper discusses introducing different modules in the existing classes to foster PI training. The PI training method for undergraduate students focuses on self-education via online videos and freely available content and self-assessment tests. Undergraduate students were given a set of questions to guide them about the important PI topics and to pay attention while self-learning the PI elements. The PI assignment starts with the familiarization of the Maslow hierarchy of needs governing the motivation behind human actions. This assignment mainly focuses on understanding the “sage” mode in which a human tends to utilize his/her latent and earned skills towards the attainment of goals and living life purposefully. The PI assignment had several questions on self-sabotaging “saboteurs” and judging traits that almost everyone develops as a survival mechanism while facing emotional and physical survival challenges for an extended period. During class discussion, students were exposed to their hidden/invisible saboteurs which could be easily triggered by unrealistic mental threats and thus compromise their learning function and performance. Students were asked to take free online self-assessment saboteur test to find the numerical values of their traits and do self-evaluation and plan to counteract the effect of self-sabotaging habits. PI training fulfills ABET student learning outcomes focusing on developing their life-long learning skills. This paper mainly discusses the PI training for graduate students under the mechanical engineering department. PI training is one of the first and essential modules in the mandatory MECH 500 Research Methods and Technical Communication course. Graduate students enrolled in this course are first introduced to the importance of PI and its potential impact in developing self-efficacy. After the initial introduction, graduate students are asked to do the following (a) Complete the abovementioned assignment given to the undergraduate student, (b) prepare a presentation on PI by including their insights for class discussion. After the PI training, students were asked to reflect on their competence in PI and the ability to apply it. In the survey and direct feedback, students expressed the value and appreciation for the PI training. Students also expressed the need to provide this training to large masses for developing an emotionally mature society of parents, teachers, and students, producing creative, innovative, and emphatic civilization.

In recent years innovation in carbon based materials have encouraged both researchers as well as industrialists to develop materials/composites with improved tribological properties. Researchers have been fascinated to develop diamond like carbon (DLC) or carbon nanotubes (CNTs) reinforced coatings to their good corrosion resistance, excellent wear resistance, good adhesion strength, and self -lubricious nature. The present review article is mainly focused on various techniques employed in order to process DLC/CNTs coatings as well as provide a summary of DLC/CNTs deposition on different substrates. The present study includes major types, properties and tribological behavior of carbon based materials and mechanisms involved in coating deposition. The study also discusses that deposition of DLC/CNTs coatings on the substrate materials enhances the wear, corrosion and mechanical properties of the substrate.

Molecular bridges covalently bonded to two ferromagnetic electrodes can transform ferromagnetic materials and produce intriguing spin transport characteristics. Previously, we theoretically and experimentally studied the impact of paramagnetic molecules on the magnetic properties of the magnetic tunnel junctions (Tyagi et al. Nanotechnology, Vol.26, p.305602, 2015). In this follow up paper we have investigated the impact of previously demonstrated molecule induced strong coupling on the spin transport. To study molecular coupling effect experimentally we attached paramagnetic molecules between two ferromagnetic electrodes of a magnetic tunnel junction along the exposed side edges. The strong molecule coupling between two ferromagnetic electrodes caused the drastic changes in transport properties of the magnetic tunnel junction testbed. Molecular transport channels along the tunnel junction edges decreased the tunneling current as compared to the leakage current of the bare tunnel junction at room temperature. The current magnitude on the paramagnetic molecule treated magnetic tunnel junction tended to settle in the suppressed state at room temperature.

As-produced laser-sintered metal additively manufactured components possess a high roughness and unsuitable surface texture that may lead to several forms of crack generation under static and dynamic loading. This problem is even more severe for additively manufactured (AM) components with intricate geometries involving a large internal surface area. Here, we report the application of the chemical polishing method to improve the surface finish of 316 steel components. After chemical polishing, the AM component surface became dull gray to bright lustrous and surface morphology improved remarkably. As a distinctive advantage, chemical polishing effectively reduces the roughness of the internal and external surfaces of the AM component. The Ra roughness parameter changed from ~ 5 to ~ 0.4 um for the outer surface. However, for the inner surface of the AM component, where abrasive blasting or shot pinning was unable to remove loose metal powder, the Ra surface roughness reduced from ~ 15 to ~ 0.4 um. Our SEM study showed that chemical polishing produced the surface texture covered with ~ 0.3-μm-wide sub-microscopic convex hull-shaped regions. During chemical polishing, material removal preferably occurred from the interior regions of the ubiquitous sub-microscopic regions. The roughness measurement conducted with SEM on a ~ 20-μm scan length chemical polished sample was Ra 0.37 μm. Roughness study in SEM was in close agreement with the roughness measurement performed with optical profilometer over several millimeter-long scan lengths resulting in a ~ 0.4-μm Ra. These studies suggested that chemical polishing produced uniform surface reduction over a large area.

In the present work, multi-walled carbon nanotubes (MWCNTs), bamboo charcoal (BC) and activated carbon (AC) have been synthesized via thermal CVD technique by adopting fixed catalyst route and by simple pyrolysis, respectively. A two-terminal device has been fabricated using either MWCNTs, BC or AC as sensing material which was kept between the two terminals. This fabricated device was used for alcohol sensing at room temperature. In order to determine the sensitivity and detection limit, one droplet (∼10 μL) of alcohol (CH3OH, C2H5OH and IPA) as well as IPA/water mixture was drop casted on the sensing material and the variation of resistance with respect to time has been monitored. The plausible explanation of detection has also been proposed taking into account the carriers tunneling between two disordered regions which was being wetted by alcohol molecules. We envision that the fabricated device might be a cost effective solution for the detection of pure as well as dilute isopropyl alcohol.

In present work, wall-to-wall joining of two parallel multiwalled carbon nanotubes (MWCNTs) has been successfully demonstrated using electron beam inside high resolution transmission electron microscope. The used MWCNTs have been grown using cobaltocene and benzene as catalyst and carbon precursor, respectively via thermal CVD technique. We have proposed that in present case, irradiation induced joining is achieved if adequate balance between sputtered carbon atoms from the outer walls of MWCNTs and generation as well as migration of defects along the tube axis is obtained. Casimir effect is not found to play dominating role in the joining process. The proposed method can potentially be used for developing wall-to-wall interconnection between MWCNTs using electron beam.

Here we demonstrate that by using sugarcane bagasse as a carbon precursor, highly crystalline diamond films possessing H3 [N-V-N] and [Si-V]− optical centers can be grown on Si (100) substrates using a simple thermal chemical vapor deposition (thermal-CVD) system at atmospheric pressure and reduced temperature (~900 °C). In this process, the rich chemistry of effluent gas species produced during the pyrolysis of sugarcane bagasse is found to play a vital role. Diamond films have also been characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM), micro-Raman, and photoluminescence (PL) spectrometer. Presence of nitrogen and silicon related defect was probed by PL and H3, i.e. [N-V-N] at 505 nm and [Si-V]− at 736 nm optical centers have been confirmed. The other observed peaks at 445.7 nm, 468 nm, and 884 nm are assigned to nitrogen-containing defects.

In this article, a structure of heterojunction solar cell configured as Ti (front contact)/p-phosphorene/n-cSi/Ag (back contact) has been simulated by using AFOSR-HET v2.5 software. Here, electronic nature of phosphorene layer which is anisotropic along armchair and zigzag directions has been considered as 3D in nature instead of 2D. After optimizing the parameters of p-type single layer phosphorene and n-type crystalline silicon (n-cSi) maximum power conversion efficiency 15.51% and 14.06% has been achieved for armchair and zigzag phosphorene, respectively. The temperature dependence of the cell performance has been studied and maximum efficiency has been found at 300 K for both armchair and zigzag phosphorene layer. Further, we have studied the effect of metal contact on the cell performance. We have also simulated the solar cell taking experimentally available parameters of n-cSi and efficiencies of 13.29% and 14.06% are found in cases of the armchair and zigzag phosphorene layers, respectively. Finally, we have demonstrated that multilayer p-type phosphorene layer could act as an effective transparent conducting electrode in the silicon heterojunction solar cell.

Magnetic tunnel junction can produce highly configurable molecular spintronics devices. This paper highlights a rather subtle attribute of magnetic tunnel junction fabrication that can lead to the very pronounced impact on magnetic properties of molecular spintronics device. We conducted magnetic studies to observe the effect of depositing ~5 nm Tantalum (Ta) on the top of a magnetic tunnel junction. We investigated the effect of Ta by using characterization techniques like ferromagnetic resonance, magnetometry, and polarized neutron reflectometry. Bridging paramagnetic molecules between the two ferromagnetic electrodes of magnetic tunnel junctions with and without Ta top layer produced the very different magnetic response.