Prevascularized medical devices can improve cell therapy. Such devices may replace whole organ transplantation with hosting only the necessary therapeutic cells. We have developed a noninvasive optical technology to study the vascularization into such medical devices. In our technique, oxygen partial pressure within a device is monitored by Oxygen Sensitive Tubes (OSTs), comprising oxygen permeable silicone tubing with inner luminal surfaces coated by an oxygen-sensitive porphyrin dye. OSTs were placed within a PDMS device and transplanted into the subcutaneous space of athymic nude mice. An optical probe placed over the skin excites the OSTs with a pulse of light and detects the luminescent lifetime of emitted light, which is uniquely related to oxygen partial pressure. Furthermore, we developed a Dynamic Inhalation Gas Test (DIGT) to determine the oxygen transport rate between the microvasculature and the device. DIGT works by monitoring oxygen partial pressure in a device following a step change in inhaled-gas oxygen content. We report DIGT oxygen dynamics measured intermittently over eight weeks. Our study shows DIGT dynamics are unique to each implant, supporting the important role of the host tissue response in the availability of oxygen over time.

A simple model system towards an impedance-probing strain sensor based on conducting tough hydrogels is demonstrated. A poly(acrylamide) hydrogel, cross-linked with N,N’-methylene-bis(acrylamide) was contacted with carbon fibres for electrical impedance analysis. The conductivity of the salt-containing hydrogel was determined to be 114 ± 10 mS/cm. Upon stretching the hydrogel samples to their fourfold initial length, the impedance response increased according to a power law. This was used to establish a sensing equation for the relation between the resistive component of the impedance signal and the applied mechanical strain under tension. This work contributes to the development of highly stretchable and soft strain sensors for applications in soft robotics.

Polyester-based shape-memory polymer actuators are multifunctional materials providing reversible macroscopic shape shifts as well as hydrolytic degradability. Here, the function-function interdependencies (between shape shifts and degradation behaviour) will determine actuation performance and its life time.

In this work, glycolide units were incorporated in poly(ε-caprolactone) based actuator materials in order to achieve an accelerated hydrolytic degradation and to explore the function-function relationship. Three different oligo[(ε-caprolactone)-co-glycolide] copolymers (OCGs) with similar molecular weights (10.5 ± 0.5 kg∙mol−1) including a glycolide content of 8, 16, and 26 mol% (ratio 1:1:1 wt%) terminated with methacrylated moieties were crosslinked. The obtained actuators provided a broad melting transition in the range from 27 to 44 °C. The hydrolytic degradation of programmed OCG actuators (200% of elongation) resulted in a reduction of sample mass to 51 wt% within 21 days at pH = 7.4 and 40 °C. Degradation results in a decrease of Tm associated to the actuating units and increasing Tm associated to the skeleton forming units. The actuation capability decreased almost linear as function of time. After 11 days of hydrolytic degradation the shape-memory functionality was lost. Accordingly, a fast degradation behaviour as required, e.g., for actuator materials intended as implant material can be realized.

Improved budgeting of heat loads arising from radiogenic heating in high level wastes (HLW) could allow enhanced usage of geological disposal facility space. Separation of high heat generating nuclides from HLW, such as Cs, would simplify management of heat loads. A potential host matrix for Cs-disposal is hollandite. The incorporation of Cs into the hollandite phase is aided by substitution of cations on the B-site of the structure; these ions may include Ni and Zn. Two series of hollandites, Ni-substituted and Zn-substituted, were synthesised via an alkoxide-nitrate route and consolidated by cold uniaxial pressing and sintering or by hot isostatic pressing. Characterisation of the resultant material by X-ray diffraction and scanning electron microscopy found that hollandite was formed for all levels of substitution. Materials produced via HIP were found to be denser indicating lower Cs loss. HIPed Ni hollandites were found to contain fewer secondary phases and it was concluded that they were the most suitable candidates

In this study, optical absorption properties of copper oxide (II) (CuO) nanoleaf structures grown by hot water treatment (HWT) method were investigated by a numerical simulation method and were compared to experimental results. For this purpose, 3D CuO nanoleaves (NLs) were synthesized by HWT, which simply involved immersing a Cu plate or thin film sample in hot deionized (DI) water. For comparison, we prepared a conventional CuO thin film by thermal oxidation of copper film at about 300 °C. Optical transmission and reflection were measured by UV/Vis/NIR (ultraviolet-visible-near-infrared) spectrophotometer, which were used to calculate optical absorptance. Numerical simulation was performed with finite difference time domain (FDTD) simulation software. Reflectance, transmittance, and absorptance of CuO NLs of different roughness (i.e. CuO NLs layer thickness) were calculated through FDTD method and compared with the experimental results. FDTD simulations predict that nanoleaves morphology enhances light absorption by improving diffuse light scattering and light trapping properties which effectively increases the optical path length without using more material as compared to the thin film structure. This can be useful for developing thinner nanostructured optoelectronic devices with low cost and high efficiency.

A catalyst layer of Pt-Sn/C (Pt:Sn 1:1 atomic ratio) was deposited on commercial carbon cloth electrodes by electrophoretic deposition (EPD). The Pt-Sn/C nanocatalyst was synthesized by the polyol method. Three current signals were applied: i) continuous direct current (CDC); ii) positive pulsed current (PPC); and iii) asymmetric alternating current (AAC). The chemical composition analysis showed the effect of the applied signal on species transferred onto the carbon cloth to form the catalyst layers. Evaluation by SEM confirmed the effect of deposition-signal on the morphology of the catalyst layer. The CDC signal formed spherical agglomerates with irregular distribution along with carbon fibers over the electrode, showing some cracks. A cross-cut view of the electrode showed that the catalyst penetrated the carbon cloth. Meanwhile, the PPC signal promoted a better deposition of the catalyst layer over the carbon cloth surface, with a thicker and more homogeneous rough layer than CDC. In contrast, the layer developed by the AAC signal showed a morphology similar to that by CDC, suggesting the formation of a layer with low metal loading. The cross-cut view of the AAC electrode showed the formation of a highly rough layer having large areas with limited contact with the carbon cloth fibers. The electro-catalytic activity of the electrodes for the Ethanol Oxidation Reaction (EOR) was studied in acid media. The CDC electrode showed an enhanced performance for the EOR by delivering the highest current density (272 mA mg-1Pt) with the more negative onset potential (341 mV) relative to the PPC and AAC electrodes.

Residual stress can considerably weaken systems with ceramics-to-metal joints. Herein, we investigate the dependence of bonding strength and residual stress variation of a ceramics-to-metal joint system on the interface wedge angle and bonding temperature condition. First, disparity between large-scale displacement models with varying work-hardening parameters was confirmed using thermal elastoplastic Finite Element Method (FEM) analysis. Each interface wedge shape was set to a plane surface to compare FEM results to experimental results related to the effect of the interface wedge angle on the practical bonding strength. The experimental results were specifically for a system consisting of Si3N4-WC/TiC/TaC bonded to Ni plate. The effects of the wedge angle of the metal side on residual stress near the interface edge were numerically predicted using FEM models. The interface wedge angles for this model, φ1 and φ2, were defined using the configuration angle between the interface and free surfaces of both materials. The numerical results showed that the stress σr on the free surface of the ceramic side was concentrated near the interface edge at which discontinuity in the stress state is generated. Dependence of the residual stress variation on both the wedge angle and temperature conditions can be predicted. It was confirmed that the bonding strength improves with decreasing residual stress in geometrical conditions. Therefore, residual stress appears to be a predominant factor affecting bonding strength. The observed fracture pattern showed that the fracture originated near the interface edges, after which small cracks propagated on the ceramic side. The residual stress is presumed to dominate bonding strength as the fracture occurred near the interface edge of the ceramic side. Results showed that the maximum bonding strength appears at the geometrical condition where the fracture pattern changes to φ2 lower than 90° of joint bonded at 980 °C. Therefore, the optimum interface wedge angle depends on a combination of materials and bonding temperature conditions, because the weak point of the bonded joint system will affect the stiffness balance of both materials and the adhesion power of the bonded interface.

Effective and pH-sensitive electrochemical monitoring of L-tryptophan using noble metal nanocatalysts was evaluated in this study. This work examined the electrocatalytic influence of nanoparticles on the oxidation of amino acids with the variation of pH in working media. Bimetallic nanohybrids of palladium, silver, and gold (e.g., Pd/Ag and Pd/Au nanoparticles) were processed using organofunctionalized alkoxysilanes (3-aminopropyltrimethoxysilane (3-APTMS) and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (EETMOS)) via a sequential reduction pathway. Transmission electron microscopy (TEM) demonstrated the role of the alkoxysilanes in determining the size of the nanoparticles and the distribution of metals in the core-shell configuration. The cluster-like morphology of PdNPs was remodeled to form bimetallic nanomaterials (Pd-AuNPs and Pd-AgNPs) with a core-shell structure. Enhancement in the electrooxidation behavior was shown to depend on the nanomaterial and the pH of the medium. The Pd-AgNPs modified electrode exhibited high sensitivity and selectivity, with characteristic amplification in cathodic peak current at lower oxidation potentials (0.659 V, 0.782 V, and 0.890 V at pH values 4, 7, and 9, respectively) due to its greater stability. Differential pulse voltammetric (DPV) scans were recorded over a wide range of concentrations from 0.1 μM to 1000μM; the Pd-AgNPs modified electrode showed the lowest limit of detection of 0.1μM at pH 4, 0.5 μM at pH 7, and 0.5 μM at pH 9.

Titanium alloys have been successfully used in the energy industry due to their stability at high temperature service, good mechanical properties and corrosion resistance. The near-α Ti-6%Al-1.5%V-1.0%Mo-0.5%Zr-0.1%C alloy, has been successfully used in several parts for geothermal energy generation. Several studies have concluded that the wear behavior of Ti alloys is generally poor; however, the specific tribosystem must be analyzed. This work analyzes the additions of 0.3%Ru, and variations of the V and Mo contents on the wear performance of a Ti alloy. Different combinations of α+β and degrees of microstructural refinement were observed depending on the composition. Wear test were undertaken by using a dry sliding block-on-ring configuration under the ASTM G77 standard. Two different loads (7 and 25 N) were used against a M2 hardened steel ring as a counter face with a hardness of 790 HV. Results showed that for the 7N load, the wear behavior is related to the volume fraction and thickness of the α phase; on the other hand, for the 25N load tests, the wear losses are directly proportional to the bulk hardness of the alloys and the α plate thickness, for this condition, best wear performance was achieved by the alloy 3 which contains 1.0wt%V, 1.8wt% Mo and 0.25wt% Ru. From the experimental results of the present study, it has been found that the wear behavior is directly related to the microstructure, e.g. amount of phases, refinement degree, applied load, and, in a lesser extent to the bulk hardness.

Metronidazole (MNZ) is an antibiotic drug to be carcinogenic and mutagenic. The present work was focused on MNZ degradation using the Fenton process, in batch studies. Five initial concentrations of MNZ (0.5, 5, 10, 15 and 20 mg/L), three Fe (II) concentrations (2.94, 5.88 and 11.66 μM), 29.4 μM H2O2, and three pH (3.5, 5 and 7) were evaluated at a reaction time of 5 min. A statistical factorial design using the program Minitab 18® was used to study the MNZ degradation. The best experimental conditions to degrade MNZ at 100% was 2.94 μM Fe2+ and pH of 3.5. Three kinetic models were used to study the degradation profile of MNZ at 2.94 μM Fe2+ and 29.4 μM H2O2, such as the first-order, the second-order, and BMG kinetic model. The BMG kinetic model was the best model to describe the MNZ degradation by Fenton process. On other hand, the optimal pH for MNZ degradation was 3.5, independently of the molar ratio Fe2+/H2O2 evaluated. At pH 5, degradation efficiencies decreased significantly, while at pH 7 the lowest degradation of MNZ was observed. Finally, the Fenton process showed the potential to degrade metronidazole.

Traditionally, CMOS transistors are for low power, high speed, and high packing density applications. CMOS is also commonly used as power regulating devices, and light sensors (CCD or CMOS image sensors). In this paper, we would like to introduce Photonic CMOS as a light emitting device for optical computing, ASIC, power transistors, and ultra large scale integration (ULSI). A Photonic CMOS Field Effect Transistor is fabricated with a low-resistance laser or LED in the drain region, and multiple photon sensors in the channel / well regions. The MOSFET, laser, and photon sensors are fabricated as one integral transistor. With embedded nonlinear optical films, the Photonic CMOSFETs have the capability of detecting and generating focused laser beams of various frequencies to perform optical computing, signal modulation, polarization, and multiplexing for digital / analog processing and communication.

Microorganisms can be present in common equipment of practice, which spread Healthcare-associated infections (HALs), generating major health issues, not only in the hospital environment but outside as well. Especially in this impending crisis due to SARS CoV-19 virus, disinfection (in general) turns out to be of paramount importance and portable disinfection in particular. The rampant spread of the COVID 19 virus, has pushed thinkers to come up with unique disinfection solutions that can help curb the spread of the virus in other places other than the medical facilities. The article aims to establish a design of a portable ultraviolet c disinfectant device that is based on the core principles of origami- the ancient Japanese art of paper folding. Resorting to origami has helped to make the device ultra-portable, robust and can be easily manufactured in order to be commercially produced as an inexpensive alternative to the cost portable disinfection devices in the market.

The effect of the combined chemical treatment of sisal fibres through the subsequent processes of mercerisation (alkali-treatment), then silane treatment and eventually acid hydrolysis, on sisal fibre were investigated. The effect of the treated fibres on the tensile strength and stiffness, flexural strength and stiffness, compression strength and shear strength of their composites with epoxy resin were also studied. Scanning electron microscopy studies of the surfaces of the treated and untreated fibres showed that the chemical treatment processes enhanced the removal of surface extractives and therefore increased the roughness of the surfaces of the fibres in the range of 20 % - 70 %. This avails an increased reinforcement surface area for interlocking with matrix and is, therefore, expected to enhance adhesion of the two. The treated fibre reinforced composites were observed to have higher values of tensile strength and stiffness, flexural strength and stiffness, compression strength and shear strength than the un-treated fibre reinforced composites. These higher values were attributed to better interfacial bonding due to better mechanical interlocking between the treated fibres and epoxy resin arising from the increased roughness of the treated fibres.

The control over the materials structure is crucial for the modulation of its properties, in order to achieve this control is important to know the formation mechanism of the material as function of parameters used. For this purpose, the effect of temperature (120, 140, 160 and 180 °C) on the hydrothermal synthesis of zinc sulphide is evaluated and a proposal of the sequence of reactions formation of zinc sulphur is presented. ZnS nanostructures with blend-phase were obtained, the temperature increment induces the growth of the nanostructure ranged between .62 and 12.72 nm, furthermore, increase the crystallinity of the ZnS nanostructures. The proposed reactions suggest the formation of a complex of thioacetamide with the Zn+2 and its subsequent decomposition into ZnS.

Antiferroelectrics have been studied for decades, with most research focused on PbZrO3 or related compounds obtained through chemical substitution. Although there are several important antiferroelectrics found in AVO4 (A=Dy, Bi), orthorhombic ABC semiconductors (e.g., MgSrSi) and hydrogen-bonded antiferroelectric materials, experimentally demonstrated antiferroelectrics are far less common. Furthermore, antiferroelectrics have potential applications in energy storage and for strain and force generators. In recent years, hybrid improper ferroelectrics have been intensively studied, along which the hybrid improper antiferroelectric phase was proposed and demonstrated in (001) Ruddlesden−Popper A3B2O7 thin films from first-principles calculations. Later, the hybrid improper antiferroelectric phase was discovered experimentally in several Ruddlesden−Popper perovskites in bulk. Across the hybrid improper ferroelectric-antiferroelectric phase transition, several interesting phenomena were also predicted. In this snapshot review, we describe recent progress in hybrid improper antiferroelectricity.

Investigations of the crystallization of aluminosilicate phases within Hanford nuclear waste glasses typically involve subjecting samples to the canister centerline cooling (CCC) schedule. This cooling schedule is representative of the slowest cooling thermal profile which these glasses will experience after the glass is poured into the high level waste (HLW) container. However, few investigations have observed how the crystallization behavior changes by varying the heat treatment schedule. In the present study, three Hanford HLW glasses are subjected to CCC and isothermal heat treatments (IHT) to better understand the evolution of phases and the chemical partitioning due to temperature schedule. Samples were characterized using electron probe microanalysis, X-ray diffraction, micro X-ray fluorescence, and micro X-ray absorption spectroscopy. From IHT, eucryptite and apatite phases were observed which were not observed during CCC. Spatially-resolved measurements demonstrated that the oxidation state of the iron was similar among glass and crystal, and we suggest a mechanism to describe the compositional fluctuations near the crystal-glass interface which influence crystallization.

Nature is ripe with biological organisms that can interact with its surroundings to continuously morph their surface texture. Many attempts have been made to optimize artificial surfaces depending on operational needs; however, most of these architected materials only focus on enhancing a specific material property or functionality. This study introduces a new class of instability-induced morphable structures, herein referred to as “Active Skins”, which enables on-demand, reversible, surface morphing through buckling-induced feature deployment. By taking advantage of a preconceived auxetic unit cell geometrical design, mechanical instabilities were introduced to facilitate rapid out-of-plane deformations when in-plane strains are applied. Here, these notches were introduced at judiciously chosen locations in an array of unit cells to elicit unique patterns of out-of-plane deformations to pave way for controlling bulk Active Skin behavior. These purposefully designed imperfections were employed for selectively actuating them for applications ranging from camouflage to surface morphing to soft robotic grippers.