Transient dynamic distributed strain sensing using photonic crystal waveguides.

This paper presents a new type of one-dimensional photonic crystal (PC) waveguide sensor and a technique for prediction of transient strain response accurately. The PC waveguide is integrated on a silicon substrate. We investigate the effect of non-uniform strain localization on the optical signal and use that information to capture the transient strain. Wavelength shift due to distributed strain field is modeled by incorporating the mechanically deformed geometry and photo-acoustic coupling through Pockels effect in a finite element formulation. We demonstrate the advantages of using our proposed method, where multiple spectral peak shift is used instead of single peak shift in order to improve sensing output accuracy and also to estimate the sensor parameter regressively, where the signal's bandwidth is limited. The maximum sensitivity of the waveguide sensor in terms of wavelength shift is estimated to be 0.36 pm/µstrain in single-peak-based sensing, whereas the proposed adaptive multispectral estimation scheme shows an enhanced sensitivity of 4.029 pm/µstrain.

Electrochemical nonenzymatic sensing of glucose using advanced nanomaterials.

An overview (with 376 refs.) is given here on the current state of methods for electrochemical sensing of glucose based on the use of advanced nanomaterials. An introduction into the field covers aspects of enzyme based sensing versus nonenzymatic sensing using nanomaterials. The next chapter cover the most commonly used nanomaterials for use in such sensors, with sections on uses of noble metals, transition metals, metal oxides, metal hydroxides, and metal sulfides, on bimetallic nanoparticles and alloys, and on other composites. A further section treats electrodes based on the use of carbon nanomaterials (with subsections on carbon nanotubes, on graphene, graphene oxide and carbon dots, and on other carbonaceous nanomaterials. The mechanisms for electro-catalysis are also discussed, and several Tables are given where the performance of sensors is being compared. Finally, the review addresses merits and limitations (such as the frequent need for working in strongly etching alkaline solutions and the need for diluting samples because sensors often have analytical ranges that are far below the glucose levels found in blood). We also address market/technology gaps in comparison to commercially available enzymatic sensors. Graphical Abstract Schematic representation of electrochemical nonenzymatic glucose sensing on the nanomaterials modified electrodes. At an applied potential, the nanomaterial-modified electrodes exhibit excellent electrocatalytic activity for direct oxidation of glucose oxidation.

Zoledronic acid in combination with alfacalcidol has additive effects on trabecular microarchitecture and mechanical properties in osteopenic ovariectomized rats.

BACKGROUND: We conducted the present study to investigate the therapeutic effects of the antiresorptive agent zoledronic acid (ZOL), alone and in combination with alfacalcidol (ALF), in a rat model of postmenopausal osteoporosis. METHODS: Female Wistar rats were ovariectomized (OVX) or sham-operated at 3 months of age. Twelve weeks post surgery, rats were randomized into six groups: (1) sham + vehicle, (2) OVX + vehicle, (3) OVX + ZOL (100 µg/kg, i.v. single dose), (4) OVX + ZOL (50 µg/kg, i.v. single dose), (5) OVX + ALF (0.5 µg/kg, oral gauge daily) and (6) OVX + ZOL (50 µg/kg, i.v. single dose) + ALF (0.5 µg/kg, oral gauge daily) for 12 weeks. After treatment, we evaluated the mechanical properties of the lumbar vertebra and femoral mid-shaft. Femurs were also tested for bone density, porosity and trabecular micro-architecture. Biochemical markers in serum and urine were also determined. RESULTS: With respect to improvement in the mechanical strength of the lumbar spine and the femoral mid-shaft, the combination treatment of ZOL and ALF was more effective than each administered as a monotherapy. Moreover, combination therapy using ZOL and ALF preserved the trabecular micro-architecture and cortical bone porosity. Furthermore, the combination treatment of ZOL and ALF corrected the decrease in serum calcium and increase in serum alkaline phosphatase and the tartarate-resistant acid phosphatase level better than single-drug therapy using ZOL or ALF in OVX rats. In addition, the combination treatment of ZOL and ALF corrected the increase in urine calcium, phosphorous and creatinine levels better than single-drug therapy using ZOL or ALF in OVX rats. CONCLUSIONS: These data suggest that the combination treatment of ZOL and ALF has a therapeutic advantage over each monotherapy for the treatment of osteoporosis.

Understanding the Heterointerfaces in Perovskite Solar Cells via Hole Selective Layer Surface Functionalization.

Interfaces in perovskite solar cells (PSCs) play a pivotal role in determining device performance by influencing charge transport and recombination. Understanding the physical processes at these interfaces is essential for achieving high-power conversion efficiency in PSCs. Particularly, the interfaces involving oxide-based transport layers are susceptible to defects like dangling bonds, excess oxygen, or oxygen deficiency. To address this issue, the surface of NiOx is passivated using octadecylphosphonic acid (ODPA), resulting in improved charge transport across the perovskite hole transport layer (HTL) interface. This surface treatment has led to the development of hysteresis-free devices with an impressive ≈13% increase in power conversion efficiency. Computational studies have explored the halide perovskite architecture of ODPA-treated HTL/Perovskite, aiming to unlock superior photovoltaic performance. The ODPA surface functionalization has demonstrated enhanced device performance, characterized by superior charge exchange capacity. Moreover, higher band-to-band recombination in photoluminescence and electroluminescence indicates presence of lower mid-gap energy states, thereby increasing the effective photogenerated carrier density. These findings are expected to promote the utilization of various phosphonic acid-based self-assembly monolayers for surface passivation of oxide-based transport layers in perovskite solar cells. Ultimately, this research contributes to the realization of efficient halide PSCs by harnessing the favorable architecture of NiOx interfaces.

Ionic Diffusion and Drug Release Behavior of Core-Shell-Functionalized Alginate-Chitosan-Based Hydrogel.

This paper reports the core-shell structure effects in calcium alginate (CaALG) microbeads due to the threshold water level for phase transition and correlates these properties with respect to pH and electrical conductivity. Further, in this study, we used a novel microfluidic device for drug release testing to study the programmed release of risedronate (RIS-anti-osteoporotic drug) encapsulated in pH-responsive CaALG-chitosan (CHT) microbeads. Our microfluidic device contains a single straight microchannel containing a steplike barrier design used to restrict the mobility of the microbeads at the sample detection zone. For optical and fluorescence microscopy, single fluorescently labeled CaALG-CHT microbead containing RIS was placed in the sample detection zone by flowing through the inlet port with ultrapure water. The RIS release behavior from the microbeads at different pH (2.1, 4, 6.8, and 7.4) conditions was determined by using a spectrophotometer connected to the outlet port of the device. Results of our first study showed that the decrease in the concentration of CaCl2 increases the swelling rate in CaALG microbeads. Maximum swelling was achieved with the lowest molar concentration of CaCl2 used for fabrication of CaALG microbeads. Further, electrical current-voltage characteristic shows the nature of ionic mobility with respect to varying levels of pH indicating electrokinetic forces developed in the CaALG microbeads. By using a microfluidic device for drug release testing, we demonstrated that a sustained release delivery system for RIS can be prepared by coating with pH-sensitive and biodegradable CaALG-CHT. The CaALG-CHT microbeads used for encapsulating RIS are resistant to the acidic environment of the stomach. This may improve the therapeutic effectiveness and reduce the gastric adverse effects associated with RIS by preventing its decomposition in the acidic condition of stomach. The newly developed microfluidic device for drug release testing may find applications in screening novel drugs and delivery systems.

Moldable biomimetic nanoscale optoelectronic platforms for simultaneous enhancement in optical absorption and charge transport.

Nano-scale patterns such as those found on the exterior surface of the eyes of certain nocturnal insects have far-reaching implications in terms of optoelectronic device design. The advantage of using these patterns for optoelectronic enhancement in photovoltaic light harvesting has been less explored due to the lack of suitable engineered materials to easily fabricate such nanostructures. Here, an attempt is made to realize these complex patterns using a self-assembly based molding process on hitherto unexplored robust structural epoxies with excellent repeatability and scalability to a larger area. The incorporation of these patterns in the substrate shows nearly a 50% broadband drop in the specular reflectance of the nanostructured substrate. Furthermore, it is demonstrated that by tweaking the bio-inspired patterns on the interior side of a light harvesting device, it is possible to obtain a broadband improvement in the external quantum efficiency in the spectral window between 350 and 650 nm leading to a significant improvement of up to 49% in the photocurrent density in the structured devices. From our experiment and simulations, it is observed that this enhancement stems from a combination of two effects: first, a broadband drop in the specular reflectance exceeding 70%, arising from trapped surface plasmon-polariton modes, and second, an improved charge separation in the structured device arising due to perturbed built-in electric fields. Furthermore, the simulations which take into account the interfacial nano-scale morphology show that for absorbers with low carrier mobilities, a significant improvement in the photocurrent and in the fill factor is simultaneously possible. Overall, this work demonstrates a combination of tweaked bio-mimetic design and the use of unconventional robust structural materials as nanostructured optoelectronic substrates. This effort can bridge the gap between naturally evolved designs and practical optoelectronics to enhance the performance.

Optimization of a Diaphragm for a Micro-Shock Tube-Based Drug Delivery Method.

This paper presents the design optimization of diaphragms for a micro-shock tube-based drug delivery device. The function of the diaphragm is to impart the required velocity and direction to the loosely held drug particles on the diaphragm through van der Waals interaction. The finite element model-based studies involved diaphragms made up of copper, brass and aluminium. The study of the influence of material and geometric parameters serves as a vital tool in optimizing the magnitude and direction of velocity distribution on the diaphragm surface. Experiments carried out using a micro-shock tube validate the final deformed shape of the diaphragms determined from the finite element simulation. The diaphragm yields a maximum velocity of 335 m/s for which the maximum deviation of the velocity vector is 0.62°. Drug particles that travel to the destination target tissue are simulated using the estimated velocity distribution and angular deviation. Further, a theoretical model of penetration helps in the prediction of the drug particle penetration in the skin tissue like a target, which is found to be 0.126 mm. The design and calibration procedure of a micro-shock tube device to alter drug particle penetration considering the skin thickness and property are presented.

Development, in vitro and in vivo characterization of zoledronic acid functionalized hydroxyapatite nanoparticle based formulation for treatment of osteoporosis in animal model.

We investigated the potential of using novel zoledronic acid (ZOL)-hydroxyapatite (HA) nanoparticle based drug formulation in a rat model of postmenopausal osteoporosis. By a classical adsorption method, nanoparticles of HA loaded with ZOL (HNLZ) drug formulation with a size range of 100-130nm were prepared. 56 female Wistar rats were ovariectomized (OVX) or sham-operated at 3months of age. Twelve weeks post surgery, rats were randomized into seven groups and treated with various doses of HNLZ (100, 50 and 25µg/kg, intravenous single dose), ZOL (100µg/kg, intravenous single dose) and HA nanoparticle (100µg/kg, intravenous single dose). Untreated OVX and sham OVX served as controls. After three months treatment period, we evaluated the mechanical properties of the lumbar vertebra and femoral mid-shaft. Femurs were also tested for trabecular microarchitecture. Sensitive biochemical markers of bone formation and bone resorption in serum were also determined. With respect to improvement in the mechanical strength of the lumbar spine and the femoral mid-shaft, the therapy with HNLZ drug formulation was more effective than ZOL therapy in OVX rats. Moreover, HNLZ drug therapy preserved the trabecular microarchitecture better than ZOL therapy in OVX rats. Furthermore, the HNLZ drug formulation corrected increase in serum levels of bone-specific alkaline phosphatase, procollagen type I N-terminal propeptide, osteocalcin, tartrate-resistant acid phosphatase 5b and C-telopeptide of type 1 collagen better than ZOL therapy in OVX rats. The results strongly suggest that HNLZ novel drug formulation appears to be more effective approach for treating severe osteoporosis in humans.

Effect of combined treatment with zoledronic acid and propranolol on mechanical strength in an rat model of disuse osteoporosis.

OBJECTIVES: A model that uses right hind-limb unloading of rats is used to study the consequences of skeletal unloading during various conditions like space flights and prolonged bed rest in elderly. This study was aimed to investigate the additive effects of antiresorptive agent zoledronic acid (ZOL), alone and in combination with propranolol (PRO) in a rat model of disuse osteoporosis. METHODS: In the present study, 3-month-old male Wistar rats had their right hind-limb immobilized (RHLI) for 10 weeks to induce osteopenia, then were randomized into four groups: 1- RHLI positive control, 2- RHLI plus ZOL (50 µg/kg, i.v. single dose), 3- RHLI plus PRO (0.1mg/kg, s.c. 5 days per week), 4- RHLI plus PRO (0.1mg/kg, s.c. 5 days per week) plus ZOL (50 µg/kg, i.v. single dose) for another 10 weeks. One group of non-immobilized rats was used as negative control. At the end of treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and bone dry and ash weight. RESULTS: With respect to improvement in the mechanical strength of the femoral mid-shaft, the combination treatment with ZOL plus PRO was more effective than ZOL or PRO monotherapy. Moreover, combination therapy using ZOL plus PRO was more effective in improving dry bone weight and preserved the cortical bone porosity better than monotherapy using ZOL or PRO in right hind-limb immobilized rats. CONCLUSIONS: These data suggest that this combined treatment with ZOL plus PRO should be recommended for the treatment of disuse osteoporosis.

Morphogenesis and mechanostabilization of complex natural and 3D printed shapes.

The natural selection and the evolutionary optimization of complex shapes in nature are closely related to their functions. Mechanostabilization of shape of biological structure via morphogenesis has several beautiful examples. With the help of simple mechanics-based modeling and experiments, we show an important causality between natural shape selection as evolutionary outcome and the mechanostabilization of seashells. The effect of biological growth on the mechanostabilization process is identified with examples of two natural shapes of seashells, one having a diametrically converging localization of stresses and the other having a helicoidally concentric localization of stresses. We demonstrate how the evolved shape enables predictable protection of soft body parts of the species. The effect of bioavailability of natural material is found to be a secondary factor compared to shape selectivity, where material microstructure only acts as a constraint to evolutionary optimization. This is confirmed by comparing the mechanostabilization behavior of three-dimensionally printed synthetic polymer structural shapes with that of natural seashells consisting of ceramic and protein. This study also highlights interesting possibilities in achieving a new design of structures made of ordinary materials which have bio-inspired optimization objectives.

Efeitos da terapia combinada com ácido zoledrônico e propranolol na resistência mecânica em um modelo de rato com osteoporose por desuso / Effect of combined treatment with zoledronic acid and propranolol on mechanical strength in an rat model of disuse osteoporosis

Resumo Objetivos: Investigar os efeitos aditivos do agente antirreabsorção ácido zoledrônico (ZOL), isolado e em combinação ao propranolol (PRO), em um modelo de rato com osteoporose por desuso. Métodos: Usou-se um modelo de pata traseira direita de rato privada de descarga de peso para estudar as consequências da falta de descarga de peso sobre o esqueleto durante várias condições, como missões espaciais e repouso prolongado no leito em idosos. Ratos Wistar machos de três meses de idade foram submetidos à imobilização da pata traseira direita (IPTD) por 10 semanas para induzir à osteopenia; em seguida, foram divididos aleatoriamente em quatro grupos: 1 – IPTD para controle positivo; 2 – IPTD mais ZOL (50 μg/kg, dose única intravenosa); 3 – IPTD mais PRO (0,1 mg/kg, via subcutânea, cinco dias na semana); 4 – IPTD mais PRO (0,1 mg/kg, via subcutânea, cinco dias na semana) mais ZOL (50 μg/kg, dose única intravenosa) por outras 10 semanas. Um grupo de ratos não imobilizados foi usado como controle negativo. No fim do tratamento, os fêmures foram removidos e testaram-se a porosidade do osso e suas propriedades mecânicas, além do peso seco e das cinzas do osso. Resultados: No que diz respeito à melhoria da resistência mecânica da diáfise femoral média, a terapia combinada com ZOL mais PRO foi mais eficaz do que a monoterapia com ZOL ou PRO. Além disso, a terapia combinada com ZOL mais PRO foi mais eficaz na melhoria do peso seco do osso e preservou melhor a porosidade do osso cortical do que a monoterapia com ZOL ou PRO em ratos submetidos à imobilização da pata traseira direita. Conclusões: Esses dados sugerem que a terapia combinada com ZOL mais PRO deve ser recomendada para o tratamento da osteoporose por desuso.

Abstract Objectives: A model that uses right hind-limb unloading of rats is used to study the consequences of skeletal unloading during various conditions like space flights and prolonged bed rest in elderly. This study was aimed to investigate the additive effects of antiresorptive agent zoledronic acid (ZOL), alone and in combination with propranolol (PRO) in a rat model of disuse osteoporosis. Methods: In the present study, 3-month-old male Wistar rats had their right hind-limb immobilized (RHLI) for 10 weeks to induce osteopenia, then were randomized into four groups: (1) RHLI positive control, (2) RHLI plus ZOL (50 μg/kg, i.v. single dose), (3) RHLI plus PRO (0.1 mg/kg, s.c. 5 days per week), (4) RHLI plus PRO (0.1 mg/kg, s.c. 5 days per week) plus ZOL (50 μg/kg, i.v. single dose) for another 10 weeks. One group of non-immobilized rats was used as negative control. At the end of treatment, the femurs were removed and tested for bone porosity, bone mechanical properties, and bone dry and ash weight. Results: With respect to improvement in the mechanical strength of the femoral mid-shaft, the combination treatment with ZOL plus PRO was more effective than ZOL or PRO monotherapy. Moreover, combination therapy using ZOL plus PRO was more effective in improving dry bone weight and preserved the cortical bone porosity better than monotherapy using ZOL or PRO in RHLI rats. Conclusions: These data suggest that this combined treatment with ZOL plus PRO should be recommended for the treatment of disuse osteoporosis.