Frequent switching of resistive memory cell may lead to a local accumulation of Joules heat in the device. Since the ReRAM cells are arranged in crossbar arrays with the two electrodes running perpendicular to each other, the heat generated in one device spreads via common electrode metal lines to the neighboring cells causing their performance degradation. Also cells that do not share any of the two electrodes (e.g. the diagonal array cells) with the hot device may also degrade provided the intermediate cells are set to an on-state establishing thus a continuous thermal conduction path between the heated and the probed device. It is found that the heat conduction along the active Cu electrode is more pronounced than that along the inert Pt electrode. Devices with Rh inert electrode performed better than those with Pt electrode due to better heat conductivity properties of Rh vs Pt. The heat dissipation is also found worse for a heated device with narrow and thin lines causing, however less degradation of more distant neighbor cells than for wide and thick metal lines. Finally, there is a trade-off between dissipating the heat quickly form the heated device to increase its maximum switching cycles and the heat exposure of the neighboring devices.

This research evidences the impact of Materials Science and Engineering Clubs as an outreach effort to expand the education and training required for a competitive Nanotechnology workforce beyond traditional STEM areas. An engineering perception questionnaire was implemented as a pre-test/post-test to track student perceptions and goals throughout the academic year to identify trends amongst gender and school level groups. Findings (107 students) show a perceived increase in student knowledge and interest for different fields of study, based on pre/post-test responses, with differences amongst gender and school level groups (middle school and high school). Also, significant differences in students’ aspirations for higher education degree were found among school level and gender. Results show that over 20% of participants increased their aspirations to higher education degrees and their interests in pursuing STEM degrees at end of the academic year. Specific findings on engineering perceptions and perceived level of knowledge and interest in science, engineering, materials, and nanotechnology as a result of club participation and student’s educational aspirations, expectations and future study plans are discussed along with implications for future STEM education.

Amorphous alloy Fe68.5Co5Nb3Cu1Si15.5B7 was obtained by melt spinning. Samples cut from the foil were annealed at 450, 550, 650 and 750 °C in a vacuum furnace. 57Fe Mӧssbauer spectroscopy was used to identify the crystalline phases formed and the orientation of the magnetic moments based on the refined values of the hyperfine parameters. The spectra of the samples annealed at 550, 650 and 750 °C were indicative of nanocrystallization, with the magnetic moments reoriented out-of-plane for the last sample. This behavior is in contradistinction to that of the Co-rich system, which was totally crystallized at these annealing temperatures. Our results show that small Co additions can lead to the formation of nanostructures over a whole range of annealing temperatures. A new series of Mӧssbauer spectra was obtained by recording simultaneously the intensity transmitted by a superposition of the sample with the stainless steel etalon, based on the dual absorber method previously introduced by us. The values of the recoilless fraction could be derived from the relative spectral areas. The f factor maintained values close to 0.7 for all samples measured, but dropped to 0.37 for the sample annealed at 750 °C. This behavior could be related to the presence of elastic stresses in the system, which caused the out-of-plane reorientation of the magnetic moment directions.

The photostability of two glycine molecules has been investigated using quantum mechanical methods i.e. at CASSCF/NEVPT2 level theory. It is found that the molecule in water shows vast photostability as a comparison to vacuum. The energies are calculated around HOMO and LUMO orbital. The NEVPT2 computed energies are reasonably matched with experimental results. The study shows that the molecule returns from higher electronically excited states to ground state through CI and AC crossings and these crossings provide a minimum energy path along derivative coupling and gradient differences vector.

This work reports by the first time a method to control the geometry of Ga2O3 films nanocrystallites at 350 °C. The formation of controlled shaped nano-crystallites of γ-Ga2O3 from amorphous Ga2O3 films grown by RF-Sputtering at room temperature driven by nano-layers of group IB metals (Cu, Ag or Au) is studied. The reported results can be explained by the role of subsurface metal nano-layers and the non-equilibrium nature of the sputtering processes. To study the effects on the surface structure and their optical properties arrays of amorphous-Ga2O3/IB-metal/amorphous-Ga2O3 were annealed in dry N2 atmosphere at 350 °C by 50, 100 and 150 min. The experimental results can be explained by the evolution of the amorphous character of the films amorphous films towards the nanocrystalline γ-Ga2O3 phase driven by the metal nano-layer seed nature. As the annealing time was increased the transition from amorphous-Ga2O3 to the nanocrystalline γ-Ga2O3 phase was detected by X-ray diffraction analysis. The transition to the nanocrystalline γ-Ga2O3 is demonstrated by the formation of octahedral, triangle and ball shape nanocrystallites with sizes of ∼5 to 50 nm according to FE-SEM analysis. The influence of the metal nano-layer is clearly seen by the shift of the plasmon frequency resonance produced by the Ga2O3/IB-metal/Ga2O3 arrays in the region from 400 to 600 nm caused by the modification of the interface Ga2O3/IB-metal produced by the applied annealing stages.

Perfect absorbers have many application in different fields including photovoltaic, antireflective coatings, defence, energy harvesting and emissivity control. Here, we have designed and fabricated a near perfect optical broadband absorber, having absorption capacity of more than 99% from 300 to 2000 nm wavelength range. Textured Silicon wafer is used as base layer to fabricate multilayered optically graded assembly, while carbon nano tubes layer is used as a top layer for impedance matching. Subsequent layers are selected as per increasing refractive index values and varying micro/nano features for efficient light trapping. Moreover, multilayered assembly shows contact angle of more than 160° with roll-off angle of less than 5° which shows that it is not only a near perfect absorber but also a self-cleaning superhydrophobic surface. Conclusively, the properties of multilayered optically graded assembly imparts attractive applications of this superabsorber in the field of photovoltaic.

Thin CdTe photovoltaic device efficiencies show significant improvement with the incorporation of a CdSeTe alloy layer deposited between a MgZnO emitter and CdTe absorber. CdTe and CdSeTe/CdTe devices fabricated by close-space sublimation with a total absorber thickness of 1.5 µm are studied using microscopy measurements and show minimal diffusion of Se into the CdTe. Current loss analysis shows that the CdSeTe layer is the primary absorber in the CdSeTe/CdTe structure, and fill factor loss analysis shows that ideality-factor reduction is the dominant mechanism of fill factor loss. Improvement in the CdSeTe/CdTe absorber quality compared to CdTe is also reflected in spectral and time-resolved photoluminescence measurements. Current density vs. voltage measurements show an increase in current density of up to 2 mA/cm2 with the addition of CdSeTe due to a band gap shift from 1.5 to 1.42 eV for CdTe and CdSeTe/CdTe absorbers respectively. Voltage deficit is lower with the incorporation of the CdSeTe layer, corroborated by improved electroluminescence intensity. The addition of CdSeTe into CdTe device structures has increased device efficiencies from 14.7% to 15.6% for absorbers with a total thickness less than two microns.

In recent decades, increasing research interest has shifted from traditional rigid skeleton robotics to flexible, shape-programmable, environmentally adaptive and stimuli-responsive “soft robotics”. Within this discipline, soft-robots capable of untethered and/or remote-controlled operation are of particular interest given their utility for actuation in complex situations with larger range of mobility and higher degrees of freedom. The use of new materials and the development of advanced fabrication techniques enable better performance and expand the utility of such soft actuators, moving them towards real-world applications. This review outlines some recent advances in untethered soft robotics and actuators to illustrate the promise of these applications at the interface of material science and device engineering.

Present work reports the growth of Strontium Barium Niobate (Sr0.75 Ba0.25 Nb2 O6, SBN 75)thin films using Pulsed laser deposition (PLD) technique for possible realization of electrically tunable modulators. Structural and optical properties of grown SBN75 thin film were investigated indicating the growth of high quality polycrystalline and optically transparent. Prism coupling technique was further utilized for coupling the incident laser light λ = 633 nm with the grown SBN75 thin film. The guided EM radiation could be further coupled with the electric field for the realization of EO modulator.

In light of growing demand and pollution versus a finite amount of resources, electronic waste recycling is a way towards material circularity. New recycling technologies not only face technical difficulties but also need to overcome challenges of feasibility in both economic and environmental aspects. An assessment regarding environmental impacts and economic factors at the early development stages of such technologies is necessary to ensure a successful establishment. A batch lab-scale process using bioleaching to win indium from electronic waste was drafted using recent research in the field. Life Cycle Assessment (LCA) was used to determine the environmental impacts in four different categories at the lowest Technology Readiness Level (TRL). The findings were then compared to two existing chemical leaching processes to put them in perspective. Results show that the electricity consumption is the major contribution to environmental impacts. The assumed bioleaching process has a higher environmental impact than the two chemical processes due to its high duration and resulting high electricity consumption. However, the research has also proven, that an LCA during the conceptual phase has a high uncertainty due to lack of data and knowledge about the process.

We synthesized precision oligomers of thiophene with cationic and hydrophobic side chains to mimic the charge, hydrophobicity, and molecular size of antibacterial host defense peptides (HDPs). In this study, the source of cationic charge was a guanidinium salt moiety intended to reflect the structure of arginine-rich HDPs. Due to the pi-conjugated oligo(thiophene) backbone structure, these compounds absorb visible light in aqueous solution and react with dissolved oxygen to produce highly biocidal reactive oxygen species (ROS). Thus, the compounds exert bactericidal activity in the dark with dramatically enhanced potency upon visible light illumination. We find that guanylation of primary amine groups enhanced the activity of the oligomers in the dark but also mitigated their light-induced activity enhancement. In addition, we also quantified their toxicity to mammalian cell membranes using a hemolysis assay with red blood cells, in the light and dark conditions.

This paper addresses the chemical synthesis and characterization of a composite formed by Li2O-Al2O3-Al3Fe-Al3Fe5O12/PCL which were obtained by the process of reduction of ferric chloride (FeCl3) with lithium aluminum hydride (LiAlH4) in an open atmosphere. The goal of the development of this hybrid material was to perform a superparamagnetic material with several potential applications. The results of the characterizations by scanning electron microscopy (SEM) and vibrating sample magnetometer showed a Li2O-Al2O3-Al3Fe-Al3Fe5O12 “desert rose stone”-like morphology 3D hierarchical powders formation when particles were sintered at 850 °C. Homogeneous nanometric particles after calcination at 1100 °C were observed. X-ray diffraction analysis were performed to determine their composition. Subsequently, the superparamagnetic powders were added by dispersion in a polycaprolactone (PCL) matrix, and then, were evaluated by SEM for the observation of their morphologies. The composite material presented a polymer network with an opened structure, a well dispersion of the oxides particles into the interstices with irregular topography and reliefs.

Bismuth ferrite (BiFeO3) and La-, Nd- and Gd-substituted bismuth ferrite of the Bi1-xLaxFeO3, Bi1-xNdxFeO3, and Bi1-xGdxFeO3 types with the atomic part of the substitution element x equal up to 0.20 were synthesized by the solid-state reaction method using powders of oxides Bi2O3, Fe2O3, and La2O3, or Nd2O3, or Gd2O3 of pure grade quality and investigated using X-ray diffraction analysis. The magnetization was measured in the magnetic field up to 6.5⋅106 A/m at 5 and 300 K. It was found that the total substitution up to 0.20 atomic part of Bi by La, Nd, and Gd leads to the paramagnetic behavior of the doped bismuth ferrite at low temperatures in a wide range of magnetic field. Strong nonlinear dependence of magnetization on the magnetic field was detected and a ferromagnetic-like dependence of magnetization was observed for small magnetic fields. This can be explained by the exchange interaction between doping magnetic ions, as well as by the exchange interaction of these ions with ions of iron. The enhancement of magnetic properties with the increase of the content of the substitution is monotone and is more pronounced for the Bi1-xGdxFeO3 ceramics.

Particular attention has been recently devoted to the development of biohybrid photoconverters based on the bacterial Reaction Center (RC) of Rhodobacter sphaeroides. This highly efficient photoenzyme has a conversion yield close to unit that makes it extremely appealing in the field of artificial photosynthesis. Isolated RCs suffer of a limited absorption cross-section in the visible spectral region that limits their applicative employment. Here we report the synthesis of two heptamethine cyanine molecules, whose photophysical properties make them potentially suitable as light harvesting antennas for the RC.

The heat transfer properties of the organic molecular crystal α-RDX were studied using three phonon scattering based thermal conductivity models. It was found that the widely used Peierls-Boltzmann model for thermal transport in crystalline materials breaks down for α-RDX. We show this breakdown is due to a large degree of anharmonicity that leads to a dominance of diffusive-like carriers. Despite being developed for disordered systems, the Allen-Feldman theory for thermal conductivity actually gives the best description of thermal transport. This is likely because diffusive carriers contribute to over 95% of the thermal conductivity in α-RDX. The dominance of diffusive carriers is larger than previously observed in other fully ordered crystalline systems. These results indicate that van der Waals bonded organic crystalline solids conduct heat in a manner more akin to amorphous materials than simple atomic crystals.

Sn2Nb2O7 and SnNb2O6 are promising candidates for wide-gap p-type conducting oxides with high mobility, because their valence-band maximum are composed of Sn 5s orbital with large spatial spreading and isotropic nature. Though hole carriers were generated by Sn4+ substitutional defects on Nb5+ site (Sn’Nb) in the substructure of Nb2O6 octahedra in both tin niobates, the generation efficiency of hole carriers in SnNb2O6 was larger than that of Sn2Nb2O7. From the variation in bond length of Nb-O in the Nb2O6 octahedra calculated by Rietveld analysis, the difference in carrier generation efficiency of two tin niobates was examined. The bond length of Nb-O in p-type Sn2Nb2O7 with large amounts of Sn’Nb was smaller than that of n-type Sn2Nb2O7 with small amounts of Sn’Nb. The holes generated by Sn’Nb were considered to be captured by the negative charge of oxygen anions consisting of the Nb2O6 octahedra, resulting in low carrier generation efficiency. In SnNb2O6 showing higher efficiency, Nb-O was 8.6 % larger than that of p-type Sn2Nb2O7. It is considered that the large Nb-O bond length provide the preferred environment for the generation of positive holes, resulting in the higher carrier generation efficiency.

The recent discovery of ferroelectric behavior in doped hafnia-based dielectrics, attributed to a non-centrosymmetric orthorhombic phase, has potential for use in attractive applications such as negative differential capacitance field-effect-transistors (NCFET) and ferroelectric random access memory devices (FeRAM). Alloying with similar oxides like ZrO2, doping with specific elements such as Si, novel processing methods, encapsulation and annealing schemes are also some of the techniques that are being explored to target structural modifications and stabilization of the non-centrosymmetric phase. In this study, we utilized synchrotron-based x-ray diffraction in the grazing incidence in plane geometry (GIIXRD) to determine the crystalline phases in hafnia-zirconia (HZO) compositional alloys deposited by atomic layer deposition (ALD). Here we compare and contrast the structural phases and ferroelectric properties of mechanically confined HZO films in metal-insulator-metal (MIM) and metal-insulator-semiconductor (MIS) structures. Both MIM and MIS structures reveals a host of reflections due to non-monoclinic phases in the d-spacing region between 1.75Å to 4Å. The non-monoclinic phases are believed to consist of tetragonal and orthorhombic phases. Compared to the MIS structures a suppression of the monoclinic phase in MIM structures with 50% zirconia or less was observed. The correlation of the electrical properties with the structural analysis obtained by GIIXRD highlights the importance of understanding the effects of the underlying substrate (metal vs. Si) for different target applications.

In this work, we report evidences of the improvement of X-ray attenuation efficiency by the addition of a very small amount of Graphene Oxide (GO) in polymer-based nanocomposite. Poly(vinylidene fluoride) (PVDF) homopolymer and barium sulfate (BaSO4) nanoparticles were mixed. PVDF/BaSO4 nanocomposite was found to attenuate 9.14% of a 20 kV X-ray beam. The addition of only 4.0 wt % of GO nanosheets to the nanocomposite improved this X-Ray attenuation efficiency to 24.56%. The respective linear attenuation coefficients (μ) were 39.9 cm-1 and 54.4 cm-1, respectively. The X-ray attenuation gradually decreases until 6.71% and 17.62%, respectively, for the X-ray beam with higher energy (100 kV). Fourier transform infrared data revealed that, due to the lack of the bending vibration modes of CF2 molecule at 656 cm-1, 688 cm-1, 723 cm-1, 776 cm-1and 796 cm-1, characteristics of the γ-crystalline phase of PVDF, the nanocomposites casted from solution are mostly in the β-ferroelectric phase of PVDF, besides the γ-paraelectric phase. SEM micrographs were used to evaluate the dispersion state of graphene sheets and the BaSO4 nanoparticles into the polymeric matrix. UV-Vis spectrometry and Differential Scanning Calorimetry (DSC) were also performed in order to complement the structural analysis. The results confirm that the addition of graphene sheets in PVDF polymer-based nanocomposites enhances the X-ray shielding efficiency. The phenomenon is discussed in terms of the reported anomalous negative thermal expansion coefficient of graphene sheets

Liquid phase analysis dominates the field of blood diagnostics and requires drawing blood volumes of several ml for each test. To achieve acceptable accuracy, each single liquid blood test requires ∼7 mL per blood sample, and repeated blood tests are often needed. Frequent testing ca result in Hospital Acquired Anemia for infants, chronically ill, and critically ill patients. Blood testing methods that can be utilized with small amounts of blood are a critical need to save lives. Theranos claimed to have developed novel methods requiring only a few nL of blood. However, Theranos’ techniques led to errors that exceeded beyond the medically acceptable threshold of 10%. This work investigates solid state blood analysis using low volumes of several µL. The most common blood tests used as first line for diagnostics and monitoring patients’ status, always include blood electrolytes, iron, and in some cases, heavy metals.

The present work investigates the formation of rapidly solidified Homogeneous Thin Solid Films (HTSFs) formed from blood drops, in order to make them suitable for solid state analysis in vacuo and in air. The solidification of ∼5 micro-liter (µL)-sized blood droplets into HTSFs is studied with two goals: achieve reproducible HTSFs optimized for producing accurate analysis, and successfully measure the potential accuracy of measurements made on HTSFs for blood electrolytes Na, K, Mg, Ca, and Cl and heavy metals such as Fe.

The blood volumes selected for this work are in the µL range, one thousandth volumes drawn for current liquid phase analysis. Balanced Saline Solution (BSS) is used as an initial liquid for testing solidification uniformity and a potential calibration material. Next, canine and human blood are studied on two types of HemaDropTM coatings for solidification: super-hydrophilic and hyper-hydrophilic. HTSF formation from BSS and blood drops are compared on both coated and uncoated surfaces.

Three solid state analytical methods are investigated in parallel to probe composition at different depths and test each for reproducibility and accuracy: Ion Beam Analysis (IBA), X-ray Fluorescence (XRF), and X-ray Photoelectron Spectroscopy (XPS). The results show that using solid films of blood yields composition, which can be reproducibly measured by IBA, XPS and XRF to varying degrees. XPS’s depth of analysis, limited to ∼5 nm, probes a small fraction of the HTSF, but provides insights into the range of thickness for homogeneous compositions in HTSFs. Statistical and error analysis help establish whether measurements taken in sets of three typically used in lab fall below the medically accepted error threshold (<10%) for each technique and element detected. Measurements are repeated and taken at various locations and on different HTSFs to establish reproducibility. XRF is of particular interest, because it is fast, accurate, portable and can be conducted in air, making it ideal for areas with limited resources.

The present work aims to explore the tribological behavior of the laser texturing process with different patterns on a Co based alloy using a pulsed Nd: YAG laser. Different parameters such as peak power, speed and spot diameter of the laser were explored for the experimental setting. The microstructural analysis was performed using scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and nanoindentation tests. The influence of the different textured patterns of the tribological performance tested with a pin-on-disc tribometer under lubricated sliding condition was evaluated. The results showed that typical interdendritic structures in the as-cast CoCr alloy condition were refined due to the heat input and fast cooling rate during the laser treatment. The refined microstructure showed less volumetric loss resulting in a increment of wear resistance and a better tribological performance than as-cast alloy. The correlation among laser parameters, microstructural effect and their influence in wear resistance is discussed.