Two-dimensional layered materials, materials with weak out-of-plane van der Waals bonding and strong in-plane covalent bonding, have attracted special attention in recent years since the isolation and characterization of monolayer graphite, the graphene. The electrical bandgap in Transition Metal Di-Chalcogenides (TMDCs), non-existent in graphene, make them a good alternative family of materials for novel electronic and optoelectronic applications. 2H- MoS2, one of the most stable TMDCs, has been extensively studied, including the synthesis methods, and its potential applications in photodetection. The chemical vapor deposition (CVD) synthesis method has increased its potential over the years. The advantages of this method are scalability compared to micromechanical exfoliation, common process used in research laboratories, and the maintenance of the quality and intrinsic properties of the material compared to the liquid exfoliation methods. In this work, we synthesized high quality pristine 2H-MoS2 via atmospheric pressure chemical vapor deposition (APCVD) by vapor phase reaction of MoO3 and S powder precursors. The samples were characterized via Raman and photoluminescence (PL) spectroscopy and compared to mechanically exfoliated MoS2 crystal by measuring the full-width half maxima (FWHM) of monolayer and few-layer mesoscopic flakes. In addition, the CVD synthesized single and few-layered MoS2 domains were transferred to different substrates using a high yield process, including a flexible substrate, preserving the quality of the material. Finally, and mechanically exfoliated MoS2 two-terminal photodetector was designed, fabricated, and measured. Demonstrating thus the capability of heterostructure fabrication and the quality of our synthesis and device fabrication process.

Adoption of Materials Science and Engineering (MSE) into the pre-college classroom is an ideal strategy for addressing Next Generation Science Standards (NGSS), specifically the Science and Engineering Practices. MSE offers core science and engineering topics that can be incorporated into existing Science, Technology, Engineering, and Mathematic (STEM) curricula through teaching modules. Using MSE as a teaching vehicle, the Center for Research on Interface Structures and Phenomena (CRISP) conducted a series of small-scale studies of its teacher professional development workshops and a student summer program, along with related teaching modules, in an effort to measure the contribution MSE has on students and K-12 STEM educators. Based on participant survey feedback, CRISP found improvement in students’ MSE knowledge, interests, and career goals. For teachers, in addition to improving their MSE knowledge, they also increased their comfort and confidence in teaching MSE concepts in their classroom. These results provide evidence for the use of MSE modules as productive teaching tools for NGSS Science and Engineering Practices, as well as producing workforce-competitive STEM students.

This paper presents a parametric study to investigate the effect of relevant design variables on mechanochemical reaction and mechanical properties of a mechanophore-embedded thermoset polymer matrix. Mechanophores emit fluorescence when a specific covalent bond breaks due to external stress, and thus have attracted immense research interest as a damage sensor. Recently, a mechanophore named dimeric 9-anthracene carboxylic acid (Di-AC) was synthesized successfully and incorporated into epoxy-based thermoset polymer matrix to detect damage precursor. However, there is significant potential in modeling the complex mechanochemistry associated with the Di-AC to obtain a better understanding of this mechanophore and its interaction with the host thermoset material. In this study, a hybrid MD simulation methodology is employed to explore this complex mechanochemistry along with the investigation of the effect of design parameters on the mechanophore performance. The hybrid MD simulation method enables the simulation of Di-AC synthesis, epoxy curing, and mechanical loading test; therefore, the experimental process performed can be emulated accurately. Previously, the hybrid MD method showed the capability of capturing experimentally observed phenomena such as early signal detection and yield strength variation between neat epoxy system and epoxy with 5 wt% Di-AC thermoset polymer. In this paper, the effect of curing temperature on mechanophore activation and mechanical properties is investigated. A series of temperatures are used in the curing simulation, which are experimentally achievable. Results show that curing temperature below glass transition temperature maintains early signal detection and yield strength decreases when the curing temperature increases above the glass transition temperature. Good correlation is observed with experimental results.

Micro-scale energy storage devices are of great importance to the advancement of low maintenance, high power electronics. They can easily be used in applications that extract energy from mechanical, solar, thermal and thermoelectric sources. Several of these devices have achieved mean areal capacitance of 1.5 mF cm-2 and maximal energy and power densities of 6.6 mJ cm-2 and 44.9 mW cm-2, respectively. It has been demonstrated that a smaller interspace enhances the performance. Currently, these types of devices are only made possible by using several micro-fabrication steps and techniques that are cost prohibitive and limit the larger scale manufacturability. We present a simple but highly scalable and cost effective method in fabricating high power interdigitated micro energy storage devices using binder-free carbon nanotubes membranes and laser irradiation to obtain interspaces on the order of 75 μm. The binder-free electrode devices show higher power density and an improved frequency response, compared to what has been reported in the literature. Additionally, we observed significant reduction in cell resistance leading to enhancement in cell capacitance, and consequently, an increase in energy density.

Bimetallic nanoparticles are of special interest for their potential applications to fuel cells, among the bimetallic systems, AuPd bimetallic nanoparticles have received great interest as they can be widely used as effective catalysts for various electrochemical reactions. Monodisperse AgPd alloy nanoparticles were synthesized by polyol method using silver nitrate and potassium tetrachloropalladate(II) in ethylene glycol as the reducing agent at 160 °C. Structural, compositional and electrochemical characterizations of synthesized bimetallic nanoparticles were investigated. High-angle annular dark field scanning/transmission electron microscopy (HAADF-STEM) images and parallel beam X-ray diffraction (XRD) of the bimetallic nanoparticles were obtained. XRD and the contrast of the HAADF-STEM images show that the bimetallic nanoparticles have an alloy structure. Cyclic voltammetry was carried out in order to confirm the electrochemical responses of the AgPd/C electrocatalysts for methanol oxidation. Thanks to the narrow size distribution of the AgPd alloy bimetallic nanoparticles (9.15 nm) the supported AgPd/C electrocatalysts have high catalytic activity toward methanol electro-oxidation.

Accurate analysis of microliter blood samples can improve patient care during medical testing and forensics. Patients can suffer from anemia due to the larger volume required for blood tests, 7 milliliters per vial. Attempts at analysis of nanoliter blood samples by Theranos have systematic errors > 10%, higher than medically acceptable thresholds. Our research aims to analyze composition of microliters of blood. This research investigates accuracy of analyzing blood via HemaDrop™, a patented technique to create a Homogenous Thin Solid Film (HTSF) on super-hydrophilic and hyper-hydrophilic surfaces with 5 microliter droplets of blood. To investigate HemaDrop™’s accuracy, Ion Beam Analysis (IBA) is conducted on dried blood spots (DBS) and HTSFs from congealed blood drops on HemaDrop™-treated samples. HTSFs are observed via optical microscopy to compare uniformity, precipitation, and phase separation. DBSs and HTSFs are compared via optical microscopy for canine blood and human blood. After drying uncoated samples, canine and human blood DBSs exhibit cratering, phase separation, and lack of uniformity. Conversely, HTSFs are uniform, exhibiting no cratering and little phase separation. Next, IBA demonstrates that HTSFs of canine and human blood solidified on super-hydrophilic and hyper-hydrophilic coatings yield spectra where species and electrolytes can be identified, unlike on DBSs. The damage curve method enables extracting accurate blood composition for elements, accounting for IBA damage. Relative error in blood elemental composition is within the 10% medical threshold. While both produced films within the 10% threshold, hyper-hydrophilic coatings eliminated phase separation from serum observed in HTSFs on super-hydrophilic coatings. HemaDrop™ provides consistent measurements independent of sample, showing HTSFs from µL blood drops are uniform, reproducible, and free of phase separation. Thus, HemaDrop™ allows for analysis in vacuum from congealed blood drops and expands the range of techniques to identify elements and molecules.

Pure and Nb-doped zirconium germanate materials of composition K2-xZr1-xNbxGe3O9.H2O where x = 0, 0.1, 0.2 and 0.3 with the structure of the natural mineral umbite have been prepared in high yield using hydrothermal synthesis methods. The parent material displays virtually no ion exchange of the K+ for Cs+ but the doped materials show rapidly enhanced exchange with replacement of ca. 70% of the K+ by Cs+ for the 30% doped material. Rietveld analysis of the powder X-ray diffraction data is consistent with no change in the unit cell parameters or K+ bonding prior to the exchange, hence we propose the improved property is due to the creation of cation defect sites within the pores of the material that facilities greater cation mobility and leads to exchange.

Medical products comprised of devices and drugs have been known as a combination product. The biodegradable collagen (Col) sponges impregnated with recombinant human bone morphogenetic protein can make bone formation hasten. It is expected further features by a combination of various growth factors and artificial bone materials. The binding properties of such factors to Col and hydroxyapatite (HAp) have not been elucidate to achieve a controlled release. In this study, we investigated artificial periosteum-like membranes made from tilapia fish Col and HAp composites as a drug carrying support. The Col-HAp composites with three different compositions in weight ratio of 2:8, 5:5 and 8:2 were made and crosslinked by irradiation of gamma-ray in wet condition. The tensile strengths of the membranes in wet or dry were depended on the compositions; however the strengths of the membranes in wet were apparently weaker at 1/10 or less than those in dry at a maximum 90 MPa. The adsorption ability of proteins, bovine serum albumin (BSA) or lysozyme (LSZ), on the membranes exhibited different tendency; the membranes including higher weight ratio of HAp adsorbed BSA rather than LSZ. These results indicated that the artificial Col-HAp membranes would be the suitable materials for biomedical device as combination products.

A good understanding of the spent fuel matrix (UO2) behavior under predisposal activities conditions is required for the proper performance assessment of a final repository. Hence, the oxidation evolution of UO2 under dry interim storage conditions, as a main predisposal action within the Spanish strategy, needs to be addressed. For this aim, in this work a detailed in situ Raman spectroscopy study of the surface oxidation of a UO2.00 disk heated in the presence of synthetic air at 573 K is presented. The spectra analysis required two previous studies. In the first one, UO2+x powder samples with controlled degree of non-stoichiometry were identified by thermogravimetric analysis and subsequently characterized by Raman spectroscopy. The equations obtained from this study enable estimating the oxidation degree of any UO2+x sample (for x < 0.20) at atmospheric conditions. The second one was performed in order to use these equations for the in situ experiments (at 573 K), since the shift of the bands due to temperature needs to be taken into account. Thus, the behavior of the Raman spectra as a function of temperature was analyzed and a correction term thereafter introduced in the initial equations.

Here, we investigate the effect of divalent metal (Zn2+, Cd2+ and Hg2+) on the structural and optoelectronic properties of methylammonium lead iodide perovskite materials prepared by the two-step deposition process. The incorporation of Cd2+ significantly improved the grain size, crystallinity, and charge carrier lifetime of CH3NH3PbI3. The inclusion of Hg2+ and Zn2+ improved the grain size compare to the control sample but adversely affected the optoelectronic properties of perovskite films. The Hg- and Zn-based impurities were formed on the surface of the films, which increased the charge trap density and lead to high non-radiative recombination rate. Time resolved photoluminescence measurements indicated that the Cd and Zn point defects do not create deep-level trap states, but the Zn-modified film showed a low lifetime due to morphology changes in the film and particle segregation on the surface.

Unusual raw materials are used to produce Tibetan black pottery in Puma township of Derge County, Sichuan Province, China. Carbonaceous, calcareous pyrite-rich illitic lakebed clay is mixed in equal proportions with a ferruginous talc-chlorite steatite. A two-stage firing process results in a dark, lustrous surface. The large amount of talc imparts many useful functional qualities to this pottery; most significant are the low thermal expansion and good thermal conduction properties of talc that make these ceramics highly suitable for heating and cooking in this high mountain region. Although used in some modern ceramics, and even in modern stoves, talc is an unusual ingredient in non-industrialized ceramics. Procurement and preparation of this resource adds to the production time but its properties and performance make talc an excellent choice for the well-being and comfort of local Tibetan households.

In this study, a multiblock copolymer containing oligo(3-methyl-morpholine-2,5-dione) (oMMD) and oligo(3-sec-butyl-morpholine-2,5-dione) (oBMD) building blocks obtained by ring-opening polymerization (ROP) of the corresponding monomers, was synthesized in a polyaddition reaction using an aliphatic diisocyanate. The multiblock copolymer (pBMD-MMD) provided a molecular weight of 40,000 g·mol−1, determined by gel permeation chromatography (GPC). Incorporation of both oligodepsipeptide segments in multiblock copolymers was confirmed by 1H NMR and Matrix Assisted Laser Desorption/Ionization Time Of Flight Mass Spectroscopy (MALDI-TOF MS) analysis. pBMD-MMD showed two separated glass transition temperatures (61 °C and 74 °C) indicating a microphase separation. Furthermore, a broad glass transition was observed by DMTA, which can be attributed to strong physical interaction i.e. by H-bonds formed between amide, ester, and urethane groups of the investigated copolymers. The obtained multiblock copolymer is supposed to own the capability to exhibit strong physical interactions.

Advanced high-strength steels as Twinning Induced Plasticity (TWIP) steels have been developed using microalloying elements and subsequent thermo-mechanical processing techniques. Moreover, under hot-working conditions, these steels undergo significant microstructural changes as a result of preferred crystallographic orientation (texture) of grains. In order to evaluate this behavior, one non-microalloyed and other single Nb-microalloyed TWIP steels were melted in an induction furnace and cast into metal and sand molds. Samples with austenitic grain sizes between 400 and 2000 µm were deformed at 800 °C and strained at a constant strain rate of 10-3 s-1, and deformation state was examined by means of electron backscatter diffraction (EBSD) technique near to the fracture tip. It was found that non-microalloyed TWIP steel solidified in both metal and sand mold exhibits dynamically recrystallized grains. On the other hand, Nb microaddition has a strong influence in TWIP steel retarding the onset of recrystallization kinetics, showing low angle sub-structured grains. Furthermore, it was possible identifying the crystallographic orientation of grains using the inverse pole figures (IPF) and the orientation distribution function (ODF). Weak cube {001}<100> recrystallization and E{111}<110> γ-fiber deformation textures components were detected.

Nanofibrous mats of poly ε-caprolactone (PCL) were fabricated by electrospinning. The nanofiber structures were investigated and characterized by scanning electron microscope, differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis, static water-contact-angle analysis and mechanical properties. The results showed that the nanofibrous PCL is an ideal biopolymer for cell adhesion, owing to its biocompatibility, biodegradability, structural stability and mechanical properties. Differential scanning calorimetry results showed that the fibrous structure of PCL does not alter its crystallinity. Studies of the mechanical properties, wettability and degradability showed that the structure of the electrospun PCL improved the tensile modulus, tensile strength, wettability and biodegradability of the nanotemplates. To evaluate the nanofibrous structure of PCL on cell adhesion, osteoblasts cells were seeded on these templates. The results showed that both adhesion and proliferation of the cells is viable on these electrospun PCL membranes. Thus electrospinning is a relatively inexpensive and scalable manufacturing technique for submicron to nanometer diameter fibers, which can be of interest in the commodity industry.

In sheet metal forming, rapid cooling of austenitized steel and CRP (cushion-ram pulsation) results in an optimized formability. An analysis is conducted regarding the influence of a stepwise deep drawing process of manganese-boron steel 22MnB5, using an oscillating ram-cushion motion at simultaneous cooling. The stops occurring in stepwise forming provide sufficient time for softening and recovery of forming properties. The microstructure can be adjusted by controlled cooling. In order to examine the newly developed process in more detail, FE simulation is applied. Thus, relevant process and material parameters can be determined. The considered values are required for profound experiments using the forming simulator BAEHR DIL 805 A/D. The softening behavior at defined forming temperatures due to CRP are examined. The experimental results of softening at distinctive temperatures provide a basis for the combined processes of stepwise hot sheet metal forming and simultaneous cooling.

Ceramic tools were made in lowland Mesopotamia from about 4500 to 2750 B.C.E. At first hammers, adzes, axes and sickles were made. By about 3300-3100 B.C.E., only sickles were made. We reverse engineered the technology to show that local, salty montmorillonite clay and quartz sand were formed into a composite blade and handle from a biconical coil and fired to 1120-1170°C based on analysis of refiring tests. At 1200°C the montmorillonite clay transforms to glass, so the firing range was right on the edge of slumping the ceramic into a useless mass. To prevent plastic deformation of the clay about 25-33 vol% of quartz sand was added. The extensive glassy matrix phase enabled the best blades to be resharpened by pressure flaking. The compositions, phase assemblage, firing temperature range, material limits on processing, and properties have been characterized for 15 sickle samples from Nippur using Xeroradiography, SEM-EDS, EPMA, and analysis of refiring tests. Strength and hardness tests and toughness calculations were conducted on replicate test tiles made using clay from Pit M at Nippur, Iraq, and sand.

Based on finds of small groups of well-fused sickles that were overfired and melted together and our experiments that demonstrated the difficulty of controlling peak temperature range and firing time for the somewhat variable raw material, the sickles probably were fired in small groups, of perhaps 10-15, in small arched, tunnel kilns that achieved high temperatures by facing somewhat predictable oncoming wind flows that provided natural draft. No evidence of workshops has been located, but, based on the archaeological finds at Nippur and our analyses, we propose that sickle-making may have been practiced as a local, seasonal, popular technology with tools being made by farmers or part-time specialists who fired in small, temporary tunnel kilns in fields or near settlements during the dependable seasonal winds. This research investigated the sickles as a well-engineered, but risk-prone ceramic manufacture that fulfilled an important a societal need, agricultural success. The technological choices of craftsmen were narrowed by raw material constraints, risk-taking, practice and workmanship to achieve desired properties and performance characteristics.

Recently, organometal halide perovskite solar cells have passed the threshold of 20 % power conversion efficiency (PCE). While such PCE values of perovskite solar cells are already competitive to those of other photovoltaic technologies, processing of large-area devices is still a challenge. Most of the devices reported in literature are prepared by small-scale solution-based processing techniques (e.g. spin-coating). Perovskite solar cells processed by vacuum thermal evaporation (VTE), which show uniform layers and achieve higher PCE and better reproducibility, have also been presented. Regarding the co-evaporation of the perovskite constituents, this technology suffers from large differences in the thermodynamic characteristics of the two species. While the organic components evaporate instantaneously at room temperature at pressures in the range of 10−6 hPa, significantly higher temperatures are needed for reasonable deposition rates of the metal halide compound. In addition, hybrid vapor phase deposition techniques have been developed employing a carrier gas to deposit the organic compound on the previously solution-processed metal halide compound. Generally, vapor phase processes have proven to be a desirable choice for industrial large-area production. In this work, we present a setup for the direct chemical vapor phase deposition (CVD) of methylammonium lead iodide (MAPbI3) employing nitrogen as carrier gas. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements are carried out to investigate the crystal quality and structural properties of the resulting perovskite. By optimizing the deposition parameters, we have produced perovskite films with a deposition rate of 30 nm/h which are comparable to those fabricated by solution processing. Furthermore, the developed CVD process can be easily scaled up to higher deposition rates and larger substrates sizes, thus rendering this technique a promising candidate for manufacturing large-area devices. Moreover, CVD of perovskite solar cells can overcome most of the limitations of liquid processing, e.g. the need for appropriate and orthogonal solvents.

Al3Nb is known as a high oxidation resistant material, while it is quite brittle. As the fracture toughness of Al3Nb single crystal and its dependence on the composition are not obtained, the micro-sized fracture testing proposed by Suzuki et al. was performed. Al3Nb single crystal micron-order size cantilevers with a chevron-notch were fabricated in a grain of two-phase polycrystalline alloys by using FIB (Focused Ion Beam). From the load-displacement curves during the bending by a nanoindenter, the average value of fracture toughness of Nb-rich Al3Nb is evaluated to be 2.90 MPam1/2, while the fracture toughness of Al-rich Al3Nb is also evaluated to be 2.82 MPam1/2. From this result, the fracture toughness of Al3Nb is less dependent on its Al/Nb ratio. Furthermore the fracture toughness of Al3 (Nb, V) was evaluated to be 2.82 MPam1/2.The fracture toughness of Al3Nb is seemingly insensitive to V addition.