It is known that tungsten oxide may be reacted with selenium sources to form WSe2 but literature reports include processing steps that involve high temperatures, reducing atmospheres, and/or oxidative pre-treatments of tungsten oxide. In this work, we report a non-vacuum process for the fabrication of compositionally high quality WSe2 thin films via the selenization of tungsten oxide under milder conditions. Tungsten source materials were various hydrated WO3 and WO2.9 compounds that were prepared using chemical solution techniques. Resulting films were selenized using a two-stage heating profile (250 °C for 15 minutes and 550 °C for 30 minutes) under a static argon atmosphere. Effects of the starting tungsten oxide phase on WSe2 formation after single and double selenization cycles were investigated using Raman spectroscopy and X-ray diffraction (XRD). After two selenization cycles, hydrated WO3 was converted to (002)-oriented WSe2 that exhibits well-resolved peaks for E12g and A1g phonon modes. Only a single selenization cycle was required to convert amorphous WO2.9 to WSe2. All selenizations in this work were achieved in non-reducing atmospheres and at lower temperatures and shorter times than any non-laser-assisted processes reported for WO3-to-WSe2 conversions.

Recently, a laboratory-scale method for measuring the rapid energy release from milligram quantities of energetic material has been developed based on the high-temperature plasma chemistry induced by a focused, nanosecond laser pulse. The ensuing exothermic chemical reactions result in an increase in the laser-induced shock wave velocity compared to inert materials. Laser-induced air shock from energetic materials (LASEM) provides a method for estimating the detonation performance of novel organic-based energetic materials prior to scale-up and full detonation testing. Here, the extension of LASEM to non-organic energetic materials is discussed. The laser-induced shock velocities from reactive materials such as Al/PTFE, Al/CuO, Al/Zr alloys, Al/aluminum iodate hexahydrate, and porous silicon composites have been measured; in many cases, the high sensitivity of the samples resulted in propagation of the reaction to the surrounding material, producing significantly higher shock velocities than conventional energetic materials. Methods for compensating for this effect will be discussed. Despite this limitation, the relative comparison of the shock velocities, emission spectra, and combustion behavior of each type of material provides some insight into the mechanisms for increasing the energy release of the material on a fast (μs) and/or slow (ms) timescale.

Ca2-αLaαNb3-βXβO10 nanosheets ((α, β=0-0.14), X= Rh(LaRh), Mn(LaMn), Fe(LaFe), Ni(LaNi)) were synthesized by exfoliation using the surfactant aided sonication method. These nanosheets demonstrated superior photocatalytic activities for water splitting into hydrogen at room temperature. SEM-EDX images and spectra confirmed the morphology and composition of the materials where doped metal precursors inserted into the heterogeneous structure aided the photocatalytic activity.

Human mesenchymal stem cells were reseeded in decellularized human bone subject to a controlled mechanical loading to create a bone-on-chip that was cultured for over 26 months. The cell morphology and their secretome were characterized using immunohistochemistry and in situ immunofluorescence under confocal microscopy. The presence of stem cell derived osteocytes was confirmed at 547 days. Different cell populations were identified. Some cells were connected by long processes and formed a network. Comparison of the MSCs in vitro reorganization and calcium response to in situ mechanical stimulation were compared to MLOY4 cells reseeded on human bone. The bone-on-chip produced an ECM of which the strength was nearly a quarter of native bone after 109 days and that contained calcium minerals at 39 days and type I collagen at 256 days. The cytoplasmic calcium concentration variations seemed to adapt to the expected in vivo mechanical load at the successive stages of cell differentiation in agreement with studies using fluid shear flow stimulation. Some degree of bone-like formation over a long period of time with the formation of a newly formed matrix was observed.

Efficient catalysts for the oxygen evolution reaction (OER) are widely applied in fuel cells and rechargeable lithium air batteries. It is desirable but challenging to achieve comparable activity to that of the noble-metal catalyst with non-precious metal catalyst. Highly active Co3O4 thin film electrodes have been successfully synthesized by a rapid one-step flame combustion synthesis method called Reactive Spray Deposition Technology. X-ray diffraction confirms the absence of any impurity phase with this synthesis process. The detailed morphology of the Co3O4 thin film is investigated with scanning electron microscopy and transmission electron microscopy. Cyclic voltammetry is used to investigate the redox activity of Co3+ to Co4+ which is crucial for the OER performance. The as-prepared Co3O4 catalyst demonstrates promising activity for OER, with an overpotential of 399 mV (at 10 mA cm-2) for OER.

Single-phase monazite-type ceramics are discussed as waste forms for the safe disposal of surplus plutonium or separated minor actinides. To derive a fundamental understanding of the long-term stability of these materials under repository relevant conditions, the dissolution kinetics of synthetic lanthanum monazite (LaPO4) were studied in dynamic dissolution experiments in the temperature range from 50 to 90°C under acidic conditions. The surface area normalised dissolution rates increased with temperature from 3.2·10-5 g m-2 d-1 at 50°C to 1.8·10-4 g m-2 d-1 at 90°C. The apparent activation energy Ea of the dissolution process was determined to be about 44 kJ mol-1, indicating a predominantly surface reaction controlled dissolution process in this temperature range. From thermodynamic considerations it can be inferred that the dissolution of the LaPO4 ceramics is governed by the dissolution of a thin layer of La-rhabdophane (LaPO4 · 0.667H2O) forming at the monazite surface in low temperature aqueous environments.

In our contribution we present and analyze implementation of the resistive switching structures for logic application based on Zadeh fuzzy logic. Resistive switching structures based on HfOx and TaOx were connected in an anti-serial configuration (complementary resistive switch). The complementary resistive switches integrated into logic circuit for Min-Max function implementation were analyzed using quasi-static voltage sweeps. We have shown that the accuracy of the Min/Max function determination depends on the ratio of the high and low resistivity states of the single switches. Determination of the Min/Max values is relevant only above the threshold voltage of the resistive structures. Reproducibility of the Min/Max function constructed from the resistive switching structures is demonstrated.

Materials science is a growing research area in Uruguay. In order to obtain a brief overview of the research done we collected information about research in this field. As a starting point, we searched in the Scopus database for the keywords: affiliation country: “Uruguay” and subject: “Materials Science” (using the “Timbó” platform). We inspected the records and we analyzed them to construct a timeline. The data show that we are in a steady state regime of number of publications that we expect to increase together with the number of students in the area, with the generation of long term policies (grants, funding opportunities), and, if we get involved in a community that promotes this area of interest.

We investigate the origin of satellite features that appear in the high-resolution x-ray absorption spectra measured at the uranium M4 edge in compounds where the uranium atoms are in the U6+ oxidation state. We employ a material-specific Anderson impurity model derived from the electronic structure obtained by the density-functional theory.

Radioactive waste with widely varying characteristics is generated from the operation and maintenance of nuclear reactors, nuclear fuel cycle facilities, research facilities and medical facilities and the through the use of radioisotopes in industrial applications. The waste needs to be treated and conditioned appropriately to provide wasteforms acceptable for safe storage and disposal. Conditioning of radioactive waste is an important step to prepare waste for long-term storage or disposal and includes the following processes:

• ▪ Immobilization which may or may not also provide volume reduction, including

  • a) Low temperature processes and

  • b) Thermal processes;

• ▪ Containerization for

  • a) Transport,

  • b) Storage, and

  • c) Disposal;

• ▪ Overpacking of primary containers

  • a) Prior to disposal and

  • b) In a disposal facility as part of disposal process.

Conditioning consists of operations that produce a waste package suitable for handling, transportation, storage and/or disposal and may be performed for a variety of reasons including standardization of practices and/or wasteforms, technical requirements for waste stability in relation to a repository design or safety case, technical requirements related to waste transportation, societal preferences, regulatory preferences, etc. This paper gives an overview of recent advances in conditioning of low- and intermediate-level radioactive waste.

The paper is based on the new IAEA Handbook “Conditioning of Low- and Intermediate-Level Liquid, Solidified and Solid Waste” which is one of eight IAEA handbooks intended to provide guidance for evaluating and implementing various characterisation and radioactive waste processing and storage technologies before final disposal

Morphological control of energetic materials (EM) is highly desired because ill-defined morphology arising from variations in processing method and supplier make it impossible to reproducibly engineer their physicochemical properties. As the most powerful, non nuclear energetic material to date, 2,4,6,8,10,12-hexanitro -2,4,6,8,10,12-hexaazaisowurtzitane (CL-20) has been the subject of significant interest for improved applications in military grade explosives. Here we report a new method for recrystallization of CL-20 from irregular bulk EMs using a surfactant assisted self-assembly process to produce uniform spherical micron-sized particles. Detailed electron microscopy studies indicate that surfactant plays a critical role in controlling CL-20 morphology. Combined X-ray diffraction and Raman spectroscopy results reveal that the resultant spherical CL-20 particles exhibit an orthorhombic β-phase crystal structure. This material is expected to display enhanced functional reproducibility due to its monodisperse nature as well as decreased shock sensitivity due to their sub-micron particle size.

High-power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers with emission wavelengths of 910 − 980 nm are extensively used in various fiber lasers and amplifiers for both telecom and defense applications. In particular, underseas and satellite communication systems require stringent reliability from these lasers. Since these lasers predominantly fail by catastrophic and sudden degradation due to COD, it is crucial especially for space satellite applications to investigate reliability, failure modes, and degradation mechanisms of these lasers. Catastrophic optical mirror damage (COMD) was known to be the only failure mode until our group reported a new failure mode in MM and SM InGaAs-AlGaAs strained QW lasers in 2009 and 2016, respectively. Our group reported that bulk failure due to catastrophic optical bulk damage (COBD) has become the dominant failure mode of both SM and MM lasers. Since there have been limited reports on COBD compared to COMD, the intent of this paper is to introduce our studies on COBD that have spanned the last decade. We investigated reliability, failure modes, and degradation processes in SM and MM InGaAs-AlGaAs strained QW lasers by performing short-term step-stress tests and long-term accelerated life-tests as well as failure mode analyses using various nondestructive and destructive micro-analytical techniques including electron beam induced current (EBIC), time-resolved electroluminescence (EL), deep level transient spectroscopy (DLTS), focused ion beam (FIB), and high-resolution TEM. EBIC and EL techniques were employed to study dark line defects generated in degraded lasers stressed under different test conditions. Time-resolved EL techniques were employed to study initiation and progressions of dark spots and dark lines in real time as lasers were aged. DLTS techniques were employed to study electron traps in both pristine and degraded lasers. Lastly, FIB and high-resolution TEM were employed to prepare cross sectional and plan view TEM specimens to study DLD areas in post-aged lasers. We also report our current understanding on degradation mechanisms responsible for COBD in both SM and MM lasers.

Dendritic growth during charging period is one of the main barriers for the rechargeablity of conventional batteries. Additionally this phenomenon hinders the utilization of high energy density metal candidates by limiting the safety and allowable operating condition for these devices. We address the role of square wave pulse on the growth dynamics of dendrites in the continuum scale and large time periods by formulating an analytical criterion. Our dimension-free analysis permits the application our results to a variety of electrochemical systems in diverse scales.

The need to improve Education for Sustainable Development (ESD) provision in Greek secondary schools offers opportunities for innovation. This study shows results of applying a more integrated, collaborative and interactive approach, developed by using elements of the Impact of Materials on Society (IMOS) course. The modules and techniques selected for teacher training and classroom implementation are presented and responses from participants are summarised. Positive feedback from the two teacher training activities and two in-class sessions with students demonstrates the potential of this approach. The paper offers evidence that a systems approach to ESD is promising and worthy of further investigation.

Recently, an epoch-making printing technology called “SuPR-NaP (Surface Photo-Reactive Nanometal Printing)” that allows easy, high-speed, and large-area manufacturing of ultrafine silver wiring patterns has been developed. Here we demonstrate low-voltage operation of organic thin-film transistors (OTFTs) composed of printed source/drain electrodes that are produced by the SuPR-NaP technique. We utilize an ultrathin layer of perfluoropolymer, Cytop, that functions not only as a base layer for producing patterned reactive surface in the SuPR-NaP technique but also as an ultrathin gate dielectric layer of OTFTs. By the use of 22 nm-thick Cytop gate dielectric layer, we successfully operate polycrystalline pentacene OTFTs below 2 V with negligible hysteresis. We also observe the improvement of carrier injection by the surface modification of printed silver electrodes. We discuss that the SuPR-NaP technique allows the production of high-capacitance gate dielectric layers as well as high-resolution printed silver electrodes, which provides promising bases for producing practical active-matrix OTFT backplanes.

In situ X-ray absorption near edge structure (XANES) measurements were conducted to elucidate the chemical states of Co and Ni catalysts during single-walled carbon nanotube (SWCNT) growth via chemical vapor deposition (CVD). XANES spectra indicated that both Co and Ni catalysts partially oxidized before heating. It was found that Co catalysts formed carbides during the SWCNT growth. In contrast, Ni catalysts remained metallic state even after the SWCNT growth had begun. These results indicate that during SWCNT growth, carbon atoms dissolve into Co particles, whereas for Ni particles, they diffuse on the surface region. It was concluded that the growth mechanisms of SWCNTs formed by CVD differed for either Co or Ni catalyst.

Understanding the precipitation of brittle hydride phases is crucial in establishing a failure criterion for various zirconium alloy nuclear fuel cladding. Accordingly, it is important to quantify the sensitivity of hydride precipitation to the component microstructure. This experimental investigation focuses on two microstructural characteristics and their role as hydride nucleation sites: The grain size and the alloy chemical composition. Samples of commercially pure zirconium (Zr-702) and Zircaloy-4, each with a wide range of grain sizes, were hydrided to 100 ppm and micrographs of the hydride distribution were optically analyzed for inter-granular and intra-granular precipitate sites. For most grain sizes, it was found that a significantly lower fraction of the precipitated hydrides nucleated at grain boundaries in Zircaloy-4 than in Zr-702, suggesting that a higher SPP content encourages the formation of intra-granular hydrides. Moreover, this effect became more prominent as the grain size increased; large-grain specimens contained a higher fraction of intra-granular hydrides than small-grain specimens of both Zr-702 and Zircaloy-4, highlighting the potency of grain boundaries as nucleation sites and how SPPs can influence the hydride distribution profile.

Zirconium has attracted a lot of attention recently due to its distinctive properties that make it suitable for extensive applications in the nuclear power and chemical industry. Zirconium and its alloys are undergoing long-term development as promising materials for the nuclear industry and power engineering. Recently, advanced Zr-based alloys are aimed for service in more severe operating conditions such as higher burn-up, increased operation temperature, and high-PH operation. In this work we observe the temperature dependence of Zr50Nb50, Zr78Nb22, Zr78Nb19Co3 and Zr50Nb49Sn1. It was observed that ternary additions with small atomic percentages of Co and Sn have significant impact on Zr-Nb alloy; and their elastic properties showed a possible enhancement on high temperature applications and physical strength.

In Northern Tanzania, high levels of fluoride in community drinking water supply is recognized as one of the major public health concern, the problem is further ameliorated by presence Escherichia coli and fecal coliform bacteria in surface water and shallow wells. Efforts to decontaminate the water involve mostly the use of low efficient bone char for fluoride removal without disinfecting the pathogens. To address this problem, a robust adsorbent which is capable of removing fluoride and microbes simultaneously with minimal diverse impact on the treated water is necessary. Here we highlight development of composite material developed from recycling of crustacean biomass waste from sea food industry. Chitosan polymer, isolated from prawns shell was composited with crab shell derived brushite (CaHPO4.2H2O) to form chitosan-hydroxyapatite composite. XRD and FT-IR analysis confirmed transformation of brushite phases into hydroxyapatite and formation hybrid composite. Fluoride adsorption tests were performed in batch mode to evaluate effectiveness. Defluoridation capacity of up to 6.4 mg/g in field water containing fluoride concentration of 5-70 mg/L was achieved. The best performance was observed with fluoride concentration of 10 mg/L and below. Apart from fluoride removal, the composite also reduced color tint and microbes from surface water samples. The pH of the treated water in most samples remained around 6.5-8.5, which is acceptable for drinking water.

The Connecticut (CT) State Colleges and Universities’ College of Technology (COT) and its Regional Center for Next Generation Manufacturing (RCNGM), a National Science Foundation (NSF) Center of Excellence, educate manufacturing technicians with necessary skills as needed by the manufacturing industry. The COT-RCNGM continuously broadens its partnerships with other community colleges, high schools and industry in New England and at the national and international levels to provide support and expertise to both students and educators in advanced manufacturing programs. The COT was founded in 1995 through state legislation to create and implement seamless pathways in engineering and technology. This system-wide collaboration of all twelve CT public community colleges, including seven state-of-the-art Advanced Manufacturing Technology Centers (AMTC) at CT’s community colleges; eight public and private universities; technical high and comprehensive high schools; and representatives from industry, including the CT Business & Industry Association (CBIA) which represents 10,000 companies. The pathways have multiple points of entry and exit for job placement and stackable credentials for degree completion, including national certifications that have increased enrollments and created program stability.

The COT is led by the Site Coordinators Council that meets monthly and consists of faculty and deans from all COT educational partners and representatives from industry and government. The Council identifies and reviews new programs, concentrations, and certificates based on industry needs and creates seamless articulated pathways. Final approval is often completed within three months for immediate implementation, allowing a timely response to workforce needs. The COT-RCNGM partners with CBIA to conduct a biannual survey of manufacturing workforce needs in CT. Educators use the survey to identify curricular needs and support funding proposals for educational programs. Asnuntuck Community College, the original AMTC, was able to use industry data from the survey to help create new programs. The RCNGM partners with other NSF grants and entities such as the National Network for Manufacturing Innovation (NNMI). The COT-RCNGM produced DVDs profiling students who have completed COT programs and work in CT manufacturing companies. The Manufacture Your Future 2.0 and the You Belong: Women in Manufacturing DVDs are distributed nationally to increase knowledge of career opportunities in manufacturing. Finally, the COT-RCNGM organizes the Greater Hartford Mini Maker Faire that brings together community members of all ages and backgrounds to share projects that promote interest in STEM fields. Participation in the Maker Movement led to involvement in a national network of Maker Faire organizers including a meeting at the White House where one organizer from each state was invited to attend and discuss the national impact of Makers.