In this communication, we report our efforts to develop amorphous silicon carbide (a-SiC) thin film photoelectrodes integrated with Si solar cells to form a monolithic, hybrid photovoltaic (PV)/a-SiC device capable of water splitting using sunlight as the only energy source. The main photoelectrochemical (PEC) properties of both the a-SiC photoelectrode and complete hybrid device fabricated by the plasma enhanced chemical vapor deposition (PECVD) technique at low temperature (≤ 200°C) are discussed. The surface modification with metal nanoparticles, which is critical to PEC performances of the hybrid device, is also described. We show that, with the an a-SiC photoelectrode of p-i-n configuration and a high performance silicon heterojunction solar cell as driver, the photocurrent of the hybrid PV/a-SiC device has reached ∼5 mA/cm2. Additionally, the durability of such device has reached ∼800 hours in acidic electrolyte. Finally, we describe a roadmap for achieving the solar-to-hydrogen efficiency of >10% by optimizing the device configuration.

A series of Ce3+ doped Ca8La2(PO4)6O2 phosphors with tunable emission were successfully synthesized by traditional solid state reaction. The crystal structure and photoluminescence properties were studied through X-ray diffraction, photoluminescence excitation and emission spectra. The results indicated that Ca8La2(PO4)6O2:Ce3+ exhibited color-tunable emission due to the 5d-4f transitions of Ce3+ ions under different wavelength excitation. The optimal doping content of Ce3+ ions in Ca8La2(PO4)6O2 was found to be 5 mol%. The site-selective photoluminescence property and the reason for red-shift of the emission band along with Ce3+ content and the excitation wavelength were also studied in detail.

This study demonstrates the potential application of glass particles doped with Zn+2 (GZn) as antimicrobial additives and atoxic of the HDPE and LLDPE polymers. Toxicity tests indicated the absence of toxicity in human cells. Microbiological tests proved the antimicrobial effect of GZn pure compound and of the additives polymeric compounds (HDPE/GZn and LLDPE/GZn). Have also indicated that with percentages of GZn higher than 2.00 wt% and a time of 4 hours the bactericidal performance is excellent and equal for both polymeric compounds.

We theoretically and experimentally investigate a novel modulation concept on silicon (Si) based on the combination of quantum confinement and plasmon enhancement effects. We experimentally study the suitability of Ge/SiGe quantum wells (QWs) on Si as the active material for a plasmon-enhanced optical modulator. We demonstrate that in QW structures absorption and modulation of light with transverse magnetic (TM) polarization are greatly enhanced due to favorable selection rules. Later, we theoretically study the plasmon propagation at the metal-Ge/SiGe QW interface. We design a novel Ge/SiGe QW structure that allows maximized overlap between the plasmonic mode and the underlying Ge/SiGe QWs.

In order to analyze the C-14 inventory and leaching rate for safety evaluation of transuranic waste disposal, it is necessary to establish an analytical method that can measure C-14 with sufficient precision [1]. Oxidative decomposition of organic compounds containing C-14 is carried out to absorb carbon dioxide (CO2) in an alkaline solution, which is mixed with a liquid scintillation cocktail, and the amount C-14 is quantified by measuring a beta ray spectrum with a liquid scintillation counter. It has been difficult to completely decompose carbon compounds in a sample, even to CO2, by using conventional oxidizing agents. In the work described here, we improved the method of oxidative decomposition used to completely decompose carbon compounds using peroxydisulfuric acid (K2S2O8). When C-14 in the form of CO2 was absorbed in a sodium hydroxide (NaOH) aqueous solution, only 80% of the actually used quantity was detected. Total organic carbon measurements showed that the entire quantity of CO2 was absorbed by NaOH. When NaOH aqueous solution was used, it was found that only the analytical value was 80%. The entire quantity of the actually used carbon could be measured by absorbing the CO2 in Carbo-Sorb®. An anion form and a neutral molecule exist in the organic compound released from activated metals. In order to identify organic compounds efficiently, fractionation into an anion and a neutral molecule and separation by high performance liquid chromatography (HPLC) are necessary. Here, we propose the combined use of an ion exchange resin and HPLC as an improved technique for identification of the chemical species.

The double-network (DN) hydrogel concept developed by J.P. Gong and Y. Osada builds upon interpenetrating networks by combining brittle and ductile components to have significantly enhanced fracture properties. The generality of the DN effect was tested by creating biopolymer-based hydrogels of methacrylated chondroitin sulfate (MCS) and polyacrylamide (PAAm) and extended upon creating DNs of MCS and poly(N,N dimethyl acrylamide) (PDMAAm), verifying that DNs were not limited to the original combination of poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS)/polyacrylamide (PAAm). Further, the mechanical properties were varied by changing the monomer concentrations, cross-linker concentrations and the addition of cross-linking groups through copolymerizations of MCS and poly(ethylene glycol) diacrylate (PEGDA). Overall, this work demonstrates that a broad range of mechanical properties achievable through DN effect under tension and compression, generally independent of the swelling degree, which is fundamentally different behavior than possible with single networks.

The sub-threshold electron transport properties of amorphous (a-) germanium telluride (GeTe) phase change material (PCM) ultra-thin films are investigated by using ab initio molecular dynamics, density function theory, and Green’s function simulations. The simulation results reproduce the trends in measured electron transport properties, e.g. current-voltage curve, intra-bandgap donor-like and acceptor-like defect states, and p-type conductivity. The underlying physical mechanism of electron transport in ultra-scaled a-PCM is unraveled. We find that, though the current-voltage curve of the ultra-scaled a-PCM resembles that of the bulk a-PCM, their physical origins are different. Unlike the electron transport in bulk a-PCM, which is governed by the Poole-Frenkel effect, the electron transport in ultra-scaled a-PCM is largely dominated by tunneling transport via intra-bandgap donor-like and acceptor-like defect states.

This work demonstrates wafer bonding using initiated chemical vapor deposition (iCVD) poly(glycidylmethacrylate) (PGMA) thin films, and studies the impact of surface treatment to manipulate adhesion energy between polymer film and silicon substrate. Substrates were modified with organosilanes or nitrogen plasma prior to iCVD and bonding. Adhesion was characterized by measuring critical energy release rate (Gc) using a 4-point bend technique. Results demonstrate a correlation between substrate surface energy and polymer-substrate adhesion energy where, depending on the functional group, close to an order of magnitude variation in adhesion energy was observed. These results point to minimal covalent interaction between polymer and substrate for these samples. Exposing the bonded wafers to a thermal anneal step led to an improved grafting of PGMA to substrate. For grafted films, the sample failure mode shifted from adhesive to cohesive, with drastic increase in Gc. These findings demonstrate that the adhesion energy and failure mode of iCVD-PGMA bonded wafers can be manipulated through surface functionalization and thermal treatment, which enable both temporary and permanent chip-bonding applications using iCVD polymer films as adhesives.

Thiolate-gold nanoclusters exhibit unique optical, magnetic and chiral properties, which are attractive for novel applications in nanotechnology. A fundamental challenge facing these nanomaterials is being able to study and understand their physical properties in various experimental conditions. To overcome this, extended X-ray absorption fine structure (EXAFS) spectroscopy can be employed to probe the Au local structure of thiolate-gold nanoclusters in a variety of conditions, providing valuable structural information from multiple bonding environments (i.e. metal-metal and metal-ligand interactions). This study discusses a methodology for conducting a multishell EXAFS fitting analysis that can be implemented for thiolate-gold nanocluster systems. Specifically, experimental and simulated EXAFS data for Au36(SR)24 nanoclusters are examined with a total of 5 scattering paths fitted to the experimental data.

A microcantliever based crack healing experiment is described and utilized in order to study the capillary nucleation rate for typical MEMS surfaces. An advanced test chamber that allows exquisite environmental control is also described and used in this study. Crack healing experiments prove to be a viable experimental technique to investigate the dynamics of capillary nucleation. The effective capillary nucleation time for the multi-asperity surface of microcantilever samples appears to increase logarithmically with adhesion energy.

Hydrogen atom H (≡ proton + electron) transfer (HAT), is the most common reaction that involves the transfer of two elementary particles, a proton and an electron. Antioxidant, proton-coupled electron transfer (PCET) reactions involve also the transfer of two elementary particles, a proton and an electron. These constitute the fundamental step in a wide range of processes, chemical energy technologies, which rely on e–/H+ transfer from combustion and aerobic oxidations, to enzymatic catalysis and the destructive effects of reactive oxygen species in vivo. Here we describe a novel phenomenon, plasmonically-enhanced PCET, using nanothin silica-coated plasmonic Ag nanoparticles, functionalized with gallic acid, a natural antioxidant molecule, that is able to perform PCET. These nanoparticles can transfer rapidly electrons and protons to stable radicals. The kinetics and yield of these PCET reactions can be enhanced by plasmonic resonance modes excited by low-power, near-Infrared (785nm) laser irradiation. The demonstration that these plasmonic nanoparticles can enhance the HAT rates for both electrons and protons expands the traditional view of interfacial PCET. The occurrence of interfacial plasmon-enhancement of PCET brings together so far unrelated domains of nanoplasmonics, electron/proton translocation with significant impact on a variety of applications and most notably in theranostics.

The increasing use of polymeric reinforcements in concrete structures requires either the development of a new design theory or the adaptation of current designs considering the engineering properties of this type of materials. In this work a method for calculating the deflections of reinforced concrete elements is proposed, which can be used in predicting the flexural behavior of longitudinally reinforced concrete with PET strips in amounts up to 1%. The model theory assumes that concrete has a tensile load capacity different to zero, characterized by a uniaxial tensile stress-strain diagram. A series of tests were conducted to corroborate the validity of the suggested method, showing that the theory also correctly predicts the creep deformation post-cracking. The deflection results of reinforced concrete with recycled PET strips are presented. The tests are carried out by a simple beam with center-point loading, using three different amounts of reinforcement and comparing the experimental results with the theoretical results of the proposed model.

Our research is focused on the engineering of novel, highly sensitive and miniaturized hybrid materials from carbon nanotubes (CNTs) and DNA molecules for applications in biosensors and medical devices. These hybrid sensors allow for a high degree of miniaturization, a key factor in the design of lightweight components while maintaining the advantages of in-situ and real-time analysis capabilities. In the first phase of the sensor design process, we investigated the structural and electrical properties of the supramolecular complexes made of amide-functionalized CNTs and double-stranded DNA. The solubilization properties of the hybrid nanotubes in aqueous solutions with different concentrations of DNA were studied, and an optimal ratio of nanotubes and biomolecules to achieve a good level of dispersion was found. Complexes formed in aqueous solution from CNTs and DNA are highly stable and maintain their properties up to one month from preparation. The morphology of the CNT-DNA composites was investigated at the nanoscale level using atomic force microscopy (AFM) and electron microscopy (SEM). Results from these experiments show the strong affinity between the surface of the amide-functionalized CNTs and the DNA strands. Further, the CNT-DNA films were investigated by atomic force microscopy in the PeakForce TUNA mode to assess the suitability of this technique in determining the local conductive properties of the hybrid films.

Liposomal drug delivery products have been already commercialized in tumor therapeutics, which can realize passive tumor targeting via enhanced permeability and retention (EPR) effect resulting from the leaky tumor vasculature. To control drug release out of the liposomes, thermo-sensitive liposomes (TSLs) have been developed so that an abrupt exposure of highly concentrated drugs to tumor tissues was enabled by locally treated thermal stimuli. As interests upon TSL have increased along with ongoing clinical trials, some types of TSLs with different physical properties in pharmacokinetics and the mechanism of drug release have been formulated. However, there are few protocols established with a desirable heat source to maximize the efficacy of different TSLs as treating tumors. In this study, we examined different protocols for the most effective application of different TSLs to tumor therapy. First, we examined if enhancing the accumulation of TSLs within tumor tissues prior to bursting drugs out of TSLs could lead to increasing anti-tumor efficacy. Second, we compared the efficiency of two different heat sources on the use of TSL, a warm water bath (42°C) and high intensity focused ultrasound (HIFU). Our study suggests that the specified protocol be setup for TSLs with different physical properties to optimally function in tumor therapies.

Ho2O3-TiO2 based metal-insulator-metal capacitors were grown by ALD, using Ho(thd)3, Ti(OCH(CH3)2)4 and ozone as precursors. The thicknesses of the films were in the range of 7.7 to 25 nm. Some of the films were post-deposited annealed in order to study the treatment effects. The capacitors were electrically characterized. Leakage current decreases as the amount of holmium increased in the films. Resistive switching behavior was obtained in the samples where the leakage current was low. This effect was also observed in Ho2O3 films, where no titanium was present in the films.

The High Throughput Experimentation (HTE) project of the Joint Center for Artificial Photosynthesis (JCAP, http://solarfuelshub.org/) performs accelerated discovery of new earth-abundant photoabsorbers and electrocatalysts. Through collaboration within the DOE solar fuels hub and with the broader research community, the new materials will be utilized in devices that efficiently convert solar energy, water and carbon dioxide into transportation fuels. JCAP-HTE builds high-throughput pipelines for the synthesis, screening and characterization of photoelectrochemical materials. In addition to a summary of these pipelines, we will describe several new screening instruments for high throughput (photo-)electrochemical measurements. These instruments are not only optimized for screening against solar fuels requirements, but also provide new tools for the broader combinatorial materials science community. We will also describe the high throughput discovery, follow-on verification, and device implementation of a new quaternary metal oxide catalyst. This rapid technology development from discovery to device implementation is a hallmark of the multi-faceted JCAP research effort.

It is well known that exposure to ultraviolet (UV) light can result in various physical and psychological diseases. Therefore, there is a strong demand for a reliable sensor to monitor UV exposure levels in the physiologically relevant intensity ranges of mW/cm2. Here, we demonstrate a UV sensor based on a silica whispering gallery mode microresonator. This UV sensor works over physiologically relevant intensity ranges with linear performance both in the forward and backward operating directions, with very high signal-to-noise ratio that can be utilized in monitoring the UV exposure for various applications.

In this report we present results comparing lateral MOSFET properties of devices fabricated on Si-face (0001) and A-face (11-20) 4H-SiC, with nitric oxide passivation anneals. We observe a field-effect mobility of 33 cm2/V.s on p-type 5×1015 doped Si-face. These devices have a peak field-effect mobility which increases with temperature, indicative of a channel mobility limited by coulomb scattering. On 1×1016 p-type A-face SiC, the peak channel mobility is observed to be 80 cm2/V.s, with a negative temperature dependence, indicating that phonon-scattering effects dominate, with a much lower density of shallow acceptor traps. This > 2x higher channel mobility would result in a substantial decrease in on-resistance, hence lower power losses, for 4H-SiC power MOSFETs with voltage ratings below 2 kV. However, MOS C-V and gate leakage measurements indicate very different oxide and interface quality on each SiC face. For example, the Fowler-Nordheim (FN) conduction-band (CB) barrier height for electron tunneling at the SiO2/SiC interface is 2.8 eV on Si-face SiC, while it is 2.5 eV or less on A-face SiC. For the valence-band side, the effective FN barrier height at the valence-band (VB) side of only 1.6 eV on A-face SiC, while the VB barrier height is about 3.1 eV on Si-face SiC. Moreover, C-V of the MOS gate on A-face indicates the presence of a high-density of deep hole traps. It is apparent that oxides on alternative crystal faces, very promising in terms of channel mobility, require further study for complete understanding and control of the interface properties.