Inorganic perovskite photodetector with chromium interdigitated electrodes is investigated. The active material is a solution processed CsPbI3 synthesized by one step deposition. The α-phase of this material is unstable at room temperature and it converts to the δ-phase at temperatures below 320°C. The stabilization of the α-phase was conducted in nitrogen environment by adding 5% weight ratio of polyethylene oxide to the equimolar mixture of PbI2 and CsI in dimethyl sulfoxide. The absorbance spectrum of the CsPbI3 with polyethylene oxide showed the emergence of a second peak at ∼ 690 nm related to the α-phase in addition to the peak at 420 nm of the δ phase. The peak in the visible range was also observed in the μ-photoluminescence spectrum at 690 nm. The interdigital structure was prepared by photolithography method to deposit 80 nm of chromium interdigitated electrodes on glass substrate with 10 μm channel width. The detector's on/off ratio and the detectivity were calculated from the current voltage curve under 100 mW/cm2 to be 9.64×103 and 9.2×109 Jones respectively.

Antimicrobial surface coatings function as a contact biocide and are extensively used to prevent the growth and transmission of pathogens on environmental surfaces. Currently, scientists and researchers are intensively working to develop antimicrobial, antiviral coating solutions that would efficiently impede/stop the contagion of COVID-19 via surface contamination. Herein we present a flavonoid-based antimicrobial surface coating fabricated by laser processing that has the potential to eradicate COVID-19 contact transmission. Quercetin-containing coatings showed better resistance to microbial colonization than antibiotic–containing ones.

The dynamic mechanical force transmitted through microenvironments during tissue formation and regeneration continuously impacts the mechanics of cells and thereby regulates gene and protein expression. The mechanical properties are altered during the process of stem cells differentiating into different lineages. At different stages of differentiation, stem cells display different mechanical properties in response to surrounding microenvironments, which depend on the subcellular structures, especially the cytoskeleton and nucleus. The mechanical properties of the cell nucleus affect protein folding and transport as well as the condensation of chromatin, through which the cell fate is regulated. These findings raise the question as to how cell mechanics change during differentiation. In this study, the mechanical properties of human bone marrow mesenchymal stem cells (hBMSCs) were determined during adipogenic and osteogenic differentiation by atomic force microscopy (AFM). The cytoskeletal structure and the modification of histone were investigated using laser confocal microscope and flow cytometry. The mechanical properties of cell nuclei at different stages of cell differentiation were compared. The stiffness of nuclei increased with time as osteogenesis was induced in hBMSCs. The H3K27me3 level increased during osteogenesis and adipogenesis according to flow cytometry analysis. Our results show conclusively that AFM is a facile and effective method to monitor stem cell differentiation. The measurement of cell mechanical properties by AFM improves our understanding on the connection between mechanics and stem cell fate.

MoS2(1-x)Te2x, the alloy of MoS2 and MoTe2 was fabricated with just co-sputtering and the combination of co-sputtering with following thermal treatment in chalcogen ambient. Phase separation, where MoTe2 was segregated rather than S and Te being uniformly distributed, was observed for some samples. From the physical structure evaluation using XRD, it was shown that the samples that was sulfurized after unintentional oxidation during shelf time exhibited no phase separation. It was suggested that oxidation of Mo or amorphous nature of the film at the chalcogenization stage may prevent the phase separation. In addition, some samples were stored in desiccator for stability evaluation. It was revealed that the samples undergo oxidation to different extent depending on the carrier gas used in tellurization. Finally, the bandgap and band structure was evaluated for samples with different Te concentration. The bandgap showed bowing behavior for different Te concentration with the bowing parameter b = -1.21 eV. Combined with the bandgap evaluation, the valence analysis with XPS showed that the band structure shifted according to the Te concentration. The shift in bandgap allows flexible band alignment which is expected to expand the materials applicability.

We continue to investigate the design, synthesis, and characterization of electrically and ionically active conjugated polythiophene copolymers for integrating a variety of biomedical devices with living tissue. This paper will describe some of our most recent results, including the development of several new monomers that can tailor the surface chemistry, adhesion, and biointegration of these materials with neural cells. Our efforts have focused on copolymers of 3,4 ethylenedioxythiophene (EDOT), functionalized variants of EDOT (including EDOT-acid and the trifunctional EPh), and dopamine (DOPA). The resulting PEDOT-based copolymers have electrical, optical, mechanical, and adhesive properties that can be precisely tailored by fine tuning the chemical composition and structure. Here we present results on EDOT-dopamine bifunctional monomers and their corresponding polymers. We discuss the design and synthesis of an EDOT-cholesterol that combines the thiophene with a biological moiety known to exhibit surface-active behaviour. We will also introduce EDOT-aldehyde and EDOT-maleimide monomers and show how they can be used as the starting point for a wide variety of functionalized monomers and polymers.

Fused deposition modelling (FDM) type of 3D printing is widely used for manufacturing complex shaped polymer products. Recently, the metal/polymer composite products can be made by 3D printer using metal/polymer composite filament. Now, we are planning to develop a new manufacturing process of the thermoelectric (TE) elements or modules by combining the FDM-type 3D printing and the degreasing-sintering process. In this work, we focused on the degreasing-sintering process of the mixture of Mg2Si and polylactic acid (PLA) powders. Mg2Si compound powder was synthesized by a liquid-solid phase reaction (LSPR) method. The powder mixtures of Mg2Si, Al and PLA were pressed and heated in a pulse discharge sintering (PDS) chamber under a vacuum in various degreasing conditions. Following the degreasing, the sintering of Mg2Si was carried out in the same PDS chamber at various starting sintering temperatures. Sintered density, Seebeck coefficient and electrical resistivity of the consolidated Mg2Si were measured and the power factor as a TE performance was estimated from the TE properties. The optimum conditions of degreasing-sintering process maximizing the sintered density and the TE performance of Al-doped Mg2Si were investigated. Furthermore, the influences of the additive amount of Al on the sintered density and the TE performance of Mg2Si fabricated via the optimized degreasing-sintering process were investigated.

Titanium is the metal of choice for many implantable devices including dental prostheses, orthopaedic devices and cardiac pacemakers. Titanium and its alloys are favoured for hard tissue replacement because of their high strength to density ratio providing excellent mechanical properties and biocompatible surface characteristics promoting in-vivo passivation due to spontaneous formation of a native protective oxide layer in the presence of an oxidizer. This study focuses on the development of a three-dimensional chemical, mechanical, surface nano-structuring (CMNS) process to induce smoothness or controlled nano-roughness on the bio-implant surfaces, particularly for applications in dental implants. CMNS is an extension of the chemical mechanical polishing (CMP) process. CMP is utilized in microelectronics manufacturing for planarizing the wafer surfaces to enable photolithography and multilayer metallization. In biomaterials applications, the same approach can be utilized to induce controlled surface nanostructure on three-dimensional implantable objects to promote or demote cell attachment. As a synergistic method of nano-structuring on the implant surfaces, CMNS also makes the titanium surface more adaptable for the bio-compatible coatings as well as the cell and tissue growth as demonstrated by the electrochemical and surface wettability evaluations on implants prepared by DI-water machining versus oil based machining.

The oxide films formed on spent fuel claddings are regarded as a potential source of the instantaneous release of radionuclides, such as 14C, after waste disposal. We investigated the instant release fraction using the irradiated oxide exfoliated from a Zircaloy-2 water rod, whose bundle burnup was 53.0 GWd/MTU. We performed a rapid leaching test in a dilute NaOH solution (pH of 12.5) for 10 min in an ultrasonic bath to ensure the release of radionuclides. The activity ratios of the leached amount to the total amount for 14C, 60Co, and 125Sb were extremely low at approximately 10-4 to 10-3, among which the maximum value was 2.65 × 10-3 for 125Sb. These ratios were higher than that predicted from the thermodynamic solubility of ZrO2, i.e., less than 10-6. However, given the low ratios, it is too conservative to regard the inventory of all radionuclides in the Zircaloy oxide as instantaneous release. A small part of the released 14C was found as volatile species.

Neutron scattering is one of the most useful methods of studying the structure of matter, with applications to biomedical, structural, magnetic and energy-related materials. Neutron-scattering instruments are installed around research reactors or accelerator-based neutron sources, and neutron guides are critical components of these facilities. They are neutron-transport optical devices consisting of state-of-the-art mirrors often tens of meters long. Here we demonstrate a novel fabrication method of all-metallic neutron guides and axisymmetric mirrors by electroplating from precision mandrels. The process allows for the fabrication of single-piece all-metal guides of prismatic and axisymmetric shapes. We also demonstrate supermirror guides and axisymmetric focusing supermirrors produced with the same technology. We present the fabrication and tests of the multilayer-coated replicated guides and optic and show that the mandrel is reproduced with high fidelity and reliability. Such supermirror optics will provide game-changing improvements in neutron techniques.

The low-temperature synthesis of bricks prepared from high-siliceous clays by the method of plastic molding of blanks was used. For the preparation of brick blanks, binary and ternary mixtures of high-siliceous clays, black sand, and bottle glass cullet were used. Gray-black low-porosity and high-porosity ceramics was obtained by sintering under conditions of oxygen deficiency. It has been established that to initiate plastic in mixtures containing high-siliceous clay, it is necessary to add montmorillonite/bentonite additives, carry out low-temperature sintering, and introduce low-melting glass additives with a melting point ranging from 750 to 800 °C. The performed investigations have shown that the sintering of mixtures with a total content of iron oxide of about 5 wt% under reducing conditions at Tsint. = 800°C for 8 h leads to the formation of glass ceramics consisting of quartz, feldspars, and a phase. The main sources of the appearance of a dark color is the formation of [Fe3+O4]4- and [Fe3+O6]9- anions in the composition of the glass phase and feldspars. By changing the contents of clay, sand, and glass in sintering, it is possible to obtain two types of ceramic materials: (a) in the form of building bricks and (b) in the form of porous fillers.

The global expansion of nuclear energy will generate increasing quantities of waste with low levels of plutonium or other nuclear materials (NM) potentially subject to International Atomic Energy Agency (IAEA) safeguards. Reducing requirements on retained wastes has the potential to reduce future demands on already strained IAEA resources. We describe an effort to help the IAEA and Member States better estimate projected waste loads and associated safeguards obligations by developing a reporting tool to estimate types and sizes of future waste-storage and -disposal facilities. States can use such information to plan waste facilities, including size and type. The IAEA can use these data for inclusion in multiple agency reports and products for the benefit of Member States.

The grain structure of electrodeposited Cobalt is important to device electrical and reliability performance. This paper describes thermal annealing studies performed on electroplated blanket and pattern Cobalt wafers. A systematic study of Co film properties and effect of various anneal parameters such as temperature, time, hydrogen pressure and thermal cycling was completed. Co film resistivity, purity, grain structure, phase composition and orientation as well as in-feature grain size have been characterized by various analytical methods such as XRD, STEM, SIMS and EBSD. It was observed that electroplated cobalt films with resistivity approaching bulk Cobalt value can be obtained by annealing in the temperature range of 300°C - 350°C which is favorable for hcp Co phase formation.

Nihonium, Nh, is one of the newly synthesized elements. It has a high atomic number of 113, putting it in the same group as thallium, Tl. The properties of this element are largely unknown, and it is of interest to assess its (hypothetical) properties in the solid state. Elements in the same group of the periodic table as Nh are known to form binary and even tertiary compounds that have important semiconductor properties. This also makes studies on Nh attractive. We performed an ab initio computational study of its electronic structure adopting the local density and generalized gradient approximations for the exchange-correlation potential. The energy band diagrams, the total energies per volume of unit cells and density of states of Nh were compared to the known experimental and theoretical properties of elemental Tl , which lies in the same column above Nh in the periodic table. Within the limits of density-functional theory, it was found that solid Nh is expected to be a metal that is most stable in a hexagonal close packing structure.

The macroscale function of multicomponent polymeric materials is dependent on their phase-morphology. Here, we investigate the morphological structure of a multiblock copolymer consisting of poly(L-lactide) and poly(ε-caprolactone) segments (PLLA-PCL), physically cross-linked by stereocomplexation with a low molecular weight poly(D-lactide) oligomer (PDLA). The effects of blend composition and PLLA-PCL molecular structure on the morphology are elucidated by AFM, TEM and SAXS. We identify the formation of a lattice pattern, composed of PLA domains within a PCL matrix, with an average domain spacing d0 = 12 – 19 nm. The size of the PLA domains were found to be proportional to the block length of the PCL segment of the copolymer and inversely proportional to the PDLA content of the blend. Changing the PLLA-PCL / PDLA ratio caused a shift in the melt transition Tm attributed to the PLA stereocomplex crystallites, indicating partial amorphous phase dilution of the PLA and PCL components within the semicrystalline material. By elucidating the phase structure and thermal character of multifunctional PLLA-PCL / PDLA blends, we illustrate how composition affects the internal structure and thermal properties of multicomponent polymeric materials. This study should facilitate the more effective incorporation of a variety of polymeric structural units capable of stimuli responsive phase transitions, where an understanding the phase-morphology of each component will enable the production of multifunctional soft-actuators with enhanced performance.

Cadmium sulfide quantum dots (CdS QDs) are semiconductor nanoparticles having sizes in the order of nanometers. They are materials that have outstanding properties for down conversion applications. These nanostructures have been used in the fabrication of white light emitting diodes (WLEDs) in the last years. However, inhomogeneous deposition of CdS QD conversion materials allows unwanted UV light escape. In addition, low efficiency due to strong self-quenching effect, incompatibility between CdS QD solution/crystal polyester resin matrix and reabsorption are common problems that need to be solved. In this work, we try to address the incompatibility between the CdS QD solution/crystal polyester resin matrix by using a solvent exchange procedure. To block the unwanted UV-light escape, we coated our devices with a mixture of graphene carbon quantum dot (GCQD) solution/crystal polyester resin matrix. The QDs and the WLED prototypes were characterized by absorption and photoluminescence (PL) spectroscopy. The QDs embedded in the matrix shown a good homogeneous dispersion. On the other hand, the mixture shown a rapid solidification. These facts indicate a good compatibility between the CdS QDs and the crystal polyester resin. We also observed a considerable reduction of unwanted near UV-light. White light emission from WLED devices with common crystal polyester resin and low-cost materials has been achieved.

ZnO films grown by ultrasonic spray pyrolysis with different Ga contents in the range of 1.0-6.5 at% on quartz substrates have been studied. The ZnO:Ga films were annealed at 400°C for 4h in a nitrogen flow. Morphology, emission, transmittance, absorbance and electrical resistivity were controlled. It is revealed that with a small content of Ga ≤ 4.0 at%, the ZnO:Ga films maintain a flat morphology, their transmittance increases to 86% together with the increase of the ZnO optical bandgap to 3.28 eV and the intensity enlargement of the near band edge (NBE) emission band A (3.188 eV). Furthermore, the new NBE emission band B (3.072 eV) appears in photoluminescence (PL) spectra at Ga contents ≥ 1.5 at%. Simultaneously, the process of decreasing electrical resistivity becomes saturating. The last effect is attributed to the self-compensation effect in n-type ZnO:Ga films related to the generation of acceptor type complexes (VZn2- - GaZn+). The thermal quenching of the PL intensities of the A and B PL bands is studded at 18-290K, which allows assigning the PL band A to the LO-phonon replica of the free exciton emission and the band B to the emission in donor-acceptor pairs: shallow donors - acceptor complexes (VZn2- - GaZn+). The NBE emission intensity drops and the ZnO optical bandgap demonstrates the shift to a lower energy at Ga doping up to ≤ 6.5 at%. Optimal Ga concentrations have been estimated to produce ZnO:Ga films with flat morphology, high optical transmittance and bright NBE emission.

This paper focuses on describing the integration of ultrananocrystalline diamond (UNCD) coating on pure titanium-based dental implants (DIs) integrated with the surface pre-treatment by chemical-mechanical nano-structuring (CMNS) process. The combination of the UNCD coating with the CMNS metal surface treatment provides a transformational process to produce a new generation of metallic implants. CMNS promotes a uniform and dense titanium oxide interface and UNCD enables higher resistance to chemical-induced corrosion by oral fluids and enhanced bone attachment due to superior bone cell growth on C atoms (element of life in human DNA and cell). The main focus of the presented research is to establish the preliminary studies on the integration of the UNCD coating process on CMNS treated dental implants to promote corrosion resistance and biocompatibility. It is demonstrated that the CMNS process in the presence of an oxidizer (1M to be optimal) induces a tailored interface to promote UNCD coating capability through effective interface passivation leading to uniform surface coverage. The final implant product is observed to have improved corrosion potential and enhanced hydrophobicity indicating better biocompatibility providing the basis for a new generation of superior DIs. The findings can further be extended to the hip, knee, and other orthopedic metallic implants, which require major performance improvements, particularly in reducing or eliminating in-vivo body fluid-induced chemical corrosion.

We demonstrate a methodology for predicting particle removal efficiency of polypropylene-based filters used in personal protective equipment, based on quantification of disorder in the context of methyl group orientation as structural motifs in conjunction with an Ising model. The corresponding Bragg-Williams order parameter is extracted through either Raman spectro-scopy or scanning electron microscopy. Temperature-dependent analysis verifies the presence of an order-disorder transition, and the methodology is applied to published data for multiple samples. The result is a method for predicting the particle removal efficiency of filters used in masks based on a material-level property.

The transport and deposition of uranium under hydrothermal conditions in the Earth’s crust has been a subject of ongoing study but is yet to be completely understood. In addition, there is little known about the fate of nuclear waste, consisting of uranium from spent fuel and other radioactive materials, upon storage in repositories or in nuclear reactor facilities. Because the nuclear waste often comes in contact with aqueous fluids in storage environments, studies of uranyl complexation with chloride and other ligands in aqueous media, to high temperature and pressure conditions, are needed. The primary purpose of this study was to investigate the speciation of aqueous uranyl (VI) chloride complexes, in solutions having a 0.05 M uranyl concentration and [Cl] concentrations ranging from 0.2 M to 6 M, under hydrothermal conditions. The aqueous uranyl chloride complexes in the samples were studied using Raman spectroscopy and the hydrothermal diamond anvil cell (HDAC), at temperatures up to 500 °C and pressures up to ~ 0.5 GPa. The uranyl bond stretching band feature occurring in the ~810 to 870 cm-1 region was fitted using the Voigt peak shape to determine the speciation of the equilibrium uranyl chloride complexes present in the samples. As expected, the n integer value of the UO2Cln+2-n complex species increases with the increase in temperature and chloride concentration, generally trending toward charge neutrality at high temperatures.

This work reports on the use of diatomaceous earth (DE) waste and organic binder derived from Corchorus olitorius, locally known as “Mrenda” in the design of an efficient water filtration membranes. Charcoal powder was incorporated to enhance the porosity of the membrane. The firing was done at temperatures varying from 700.0 °C to 1150.0 °C. The DE waste samples comprised 79.0% silica (by mass) and 11.0% total flux content compared to porter’s clay that had 50.0% silica, 28.8% AL2O3 and 7.0% total flux content. On the other hand, the “Mrenda” binder contained 6.5% total organic matter. The use of the plant-derived binder enhanced the mechanical strength of the greenware by 52.7% and the fired membranes by 152.2%. The fabricated DE waste-based membranes were 15.0% stronger than clay-based ceramic membranes prepared under similar conditions. A sintering temperature of 900.0 °C was optimal in producing porous membranes for filtering of 4.1 liters of water per hour. The pore diameter of the membranes fabricated from DE waste only ranged between 2.0 nm – 99.0 nm. On micro-organisms filtering efficacy, the DE waste-based membranes and those fabricated with 5.0% charcoal were 99.9% and 88.4% effective in the removal of E. coli and Rotavirus respectively.