Early Bone Healing on Hydroxyapatite-Coated and Chemically-Modified Hydrophilic Implant Surfaces in an Ovine Model

Implant topography affects early peri-implant bone healing by changing the osteoconduction rate in the surrounding biological environment. Implant surfaces have been designed to promote faster and stronger bone formation for rapid and stable prosthesis loading. Early peri-implant bone healing has been observed with a sandblasted, acid-etched implant that was chemically modified to be hydrophilic (cmSLA). The present study investigates whether early peri-implant bone healing extends to a rough surface implant with a high crystalline hydroxyapatite surface (TSV MP-1 HA). Three implants were randomly placed in porous trabecular bone within both medial femoral condyles of 10 sheep. Early peri-implant bone stability was measured at 3- and 6-weeks healing time following implant insertion. Results indicated a similar implant stability quotient between the implants at insertion and over time. The significant increase over time of reverse torque values with respect to insertion torque (p < 0.001) did not differ between the implants. However, the bone-to-implant contact of TSV MP-1 HA was significantly higher than that of cmSLA implants at 6 weeks (p < 0.01). These data validate previous findings of a hydrophilic implant surface and extend the observation of early osseointegration to a rough surface implant in porous trabecular bone.     

One-Step Synthesis of Zirconia and Magnetite Nanocomposite Immobilized Chitosan for Micro-Solid-Phase Extraction of Organophosphorous Pesticides from Juice and Water Samples Prior to Gas Chromatography/Mass Spectroscopy

In this research, a magnetic sorbent was prepared by immobilizing zirconia and magnetite (Fe₃O₄) nanoparticles in chitosan, which is characterized and used as an effective nanosorbent in magnetic dispersive micro-solid-phase extraction (MDMSPE) of organophosphorous pesticides (OPPs) from juice and water samples prior to gas chromatography-mass detection (GC-MS). The properties and morphology of synthesized sorbent were characterized by scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM), and differential scanning calorimetric (DSC) analysis. The main experimental parameters including pH level, extraction time, sorbent mass, salt concentration, and desorption conditions were investigated and optimized to maximize extraction efficiency. Under optimized conditions, the calibration curves were obtained in the concentration range of 0.1–500 ng mL^?1 with correlation coefficients between 0.9993 and 0.9999. The limits of detection (signal-to-noise ratio (S/N) = 3) and limits of quantification (S/N = 10) of the method ranged from 0.031 to 0.034 ng mL^?1 and 0.105–0.112 ng mL^?1, respectively. The intra-day and inter-day RSDs were 2.2–5.7 and 2.5–7.5%, respectively. The method was successfully applied to the analysis of OPPs in fruit juices (apple, peach, and cherry) and water (mineral, tap, and river) real samples, with recoveries in the range of 86.0–106.0% for the spiked juice and water samples. The results showed that with combination of high selectivity of zirconia and magnetic property of magnetite as well as immobilizing ability of chitosan, the fabricated sorbent exhibited exceptional extraction ability toward the OPPs.     

Triple‐faced polypropylene: Fire retardant,thermally stable,and antioxidative

A halogen‐free nitrogen‐rich additive was used to make polypropylene (PP) prepared for three different missions: fire retardancy, thermal stability, and antioxidative properties. The prepared additive was composed of a cyclodextrin, a nanohydroxyapatite, and a poly[[6‐[(1,1,3,3,‐tetramethylbutyl)amino]‐1,3,5‐triazine‐2,4‐diyl][(2,2,6,6‐tetramethyl‐4‐piperidinyl)imino]‐1,6‐hexanediyl[2,2,6,6‐tetramethyl‐4‐piperidinyl)imino] (SABO®STAB) integrated into a unique molecule, namely, BSDH. Fire retardancy performance of BSDH in PP was compared with that of 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) commercially available additive in terms of cone calorimeter results. Thermal stabilities of PP/BSDH and PP/DOPO composites were compared by changes observed in pyrolysis activation energy values measured in thermogravimetric analysis under nitrogen atmosphere at various heating rates. Flame retardancy of PP/BSDH composite was reflected in a drop in the peak of Heat Release Rate by ca. 31% with respect to neat PP. Very interestingly, the results show that BSDH additive retarded thermal oxidation of PP macromolecular chains when compared with DOPO commercially available flame retardant, as signaled by a rise in oxidation induction time value as well as an increased early‐stage activation energy needed for thermal decomposition of PP in the presence of BSDH. J. VINYL ADDIT. TECHNOL., 25:366–376, 2019. © 2019 Society of Plastics Engineers     

Analytical modeling of trilayer graphene nanoribbon Schottky-barrier FET for high-speed switching applications

Recent development of trilayer graphene nanoribbon Schottky-barrier field-effect transistors (FETs) will be governed by transistor electrostatics and quantum effects that impose scaling limits like those of Si metal-oxide-semiconductor field-effect transistors. The current–voltage characteristic of a Schottky-barrier FET has been studied as a function of physical parameters such as effective mass, graphene nanoribbon length, gate insulator thickness, and electrical parameters such as Schottky barrier height and applied bias voltage. In this paper, the scaling behaviors of a Schottky-barrier FET using trilayer graphene nanoribbon are studied and analytically modeled. A novel analytical method is also presented for describing a switch in a Schottky-contact double-gate trilayer graphene nanoribbon FET. In the proposed model, different stacking arrangements of trilayer graphene nanoribbon are assumed as metal and semiconductor contacts to form a Schottky transistor. Based on this assumption, an analytical model and numerical solution of the junction current–voltage are presented in which the applied bias voltage and channel length dependence characteristics are highlighted. The model is then compared with other types of transistors. The developed model can assist in comprehending experiments involving graphene nanoribbon Schottky-barrier FETs. It is demonstrated that the proposed structure exhibits negligible short-channel effects, an improved on-current, realistic threshold voltage, and opposite subthreshold slope and meets the International Technology Roadmap for Semiconductors near-term guidelines. Finally, the results showed that there is a fast transient between on-off states. In other words, the suggested model can be used as a high-speed switch where the value of subthreshold slope is small and thus leads to less power consumption.     

Design of efficient photocatalytic processes for the production of hydrogen from biomass derived substrates

The photoreforming of glucose has been studied over TiO₂ photocatalyst with different photoreactors, focusing on the effect of the reaction conditions: temperature, pressure, catalyst and substrate concentration. The effect of pressure was particularly significant, decreasing hydrogen evolution rate, but improving the conversion of the substrate. Furthermore, pressure moderately higher than ambient allowed to operate at high temperature (80 °C), boosting hydrogen productivity. Most experiments were carried out on glucose photoreforming, but, for the first time, the photoconversion of levulinic acid was investigated, as an interesting product of biomass hydrolysis under harsh conditions. Levulinic acid led to the production of ethane and ethylene in gas phase, interpreted according to a preliminary hypothesis of the photoconversion mechanism. High hydrogen productivity was achieved, in most cases higher than the literature benchmark.     

Multimodal Label-Free Monitoring of Adipogenic Stem Cell Differentiation Using Endogenous Optical Biomarkers

Stem cell-based therapies carry significant promise for treating human diseases. However, clinical translation of stem cell transplants for effective treatment requires precise non-destructive evaluation of the purity of stem cells with high sensitivity (<0.001% of the number of cells). Here, a novel methodology using hyperspectral imaging (HSI) combined with spectral angle mapping-based machine learning analysis is reported to distinguish differentiating human adipose-derived stem cells (hASCs) from control stem cells. The spectral signature of adipogenesis generated by the HSI method enables identifying differentiated cells at single-cell resolution. The label-free HSI method is compared with the standard techniques such as Oil Red O staining, fluorescence microscopy, and qPCR that are routinely used to evaluate adipogenic differentiation of hASCs. HSI is successfully used to assess the abundance of adipocytes derived from transplanted cells in a transgenic mice model. Further, Raman microscopy and multiphoton-based metabolic imaging is performed to provide complementary information for the functional imaging of the hASCs. Finally, the HSI method is validated using matrix-assisted laser desorption/ionization-mass spectrometry imaging of the stem cells. The study presented here demonstrates that multimodal imaging methods enable label-free identification of stem cell differentiation with high spatial and chemical resolution.     

Process Intensification by Exploiting Diluted 2nd Generation Bio-ethanol in the Low-Temperature Steam Reforming Process

Second generation bioethanol, obtained by the fermentation of lignocellulosic biomass, which is not competitive with the food and feed field, is one of the most interesting promising biofuels, already available in semi-commercial amount. Steam reforming of bioethanol has been used here for sustainable hydrogen and syngas production. Differently purified second generation bioethanol feeds, directly supplied by an industrial plant, for the steam reforming process, assessing the influence of impurities and catalyst formulation. Ni/La₂O₃, Ni/ZrO₂ and Ni/CaO–ZrO₂ prepared by Flame Spray Pyrolysis were used as catalysts. Catalytic performance at high and low temperature was evaluated in order to investigate a broad range of temperature, which is one of the most critical condition in term of catalyst activity and deactivation, besides energy saving. The possible effect of impurities contained in less purified feedstocks is also discussed. Stable performance up to 100 h-on-stream was attained even under stressing reaction conditions.