Quadrature oscillator using CCCCTAs and grounded capacitors with amplitude controllability

The realisation of two electronically tunable current-mode quadrature oscillators using Current Controlled Current Conveyor Tranconductance Amplifiers (CCCCTAs) and grounded capacitors is presented. The proposed circuits offer the following advantages. The condition of oscillation and the frequency of oscillation can be orthogonally controlled. Availability of electronic control of amplitude of output current is achieved. The oscillators have high outputs impedance which facilitates easy driving an external load without additional current buffers. The proposed circuits are constructed by using two active elements and all grounded capacitors which are attractive for integration and have low active and passive sensitivities. The PSPICE simulation and experimental results are included to show the workability of the proposed circuit.     

The fundamental parameters of chitosan in polymer scaffolds affecting osteoblasts (MC3T3-E1)

The aim of this study was to investigate the degree of deacetylation (DD) and molecular weight (MW) of chitosan within chitosan–collagen scaffolds on mouse osteoblasts (MC3T3-E1). The chitosan–collagen scaffolds were fabricated by freeze-drying technique. The studies on cell attachment and proliferation, alkaline phosphatase (ALP) activity, cell morphology, and mineralized nodule formation by osteoblasts on scaffolds were investigated. No statistically significant difference was found on cell attachment, but the chitosan–collagen scaffolds with low-DD chitosan had a statistically significantly (P < 0.05) higher proliferative effect and ALP activity than those scaffolds with high-DD chitosan, regardless of molecular weight. Scanning electron images demonstrated that MC3T3-E1 cells grew well on all test scaffolds; on the contrary, mineralized nodule formation was not found. In conclusion, the DD of chitosan is a crucial factor for MC3T3-E1 cells and it should be considered in further applications for bone tissue engineering.     

Flexible,lead-free,gamma-shielding materials based on natural rubber/metal oxide composites

Properties such as gamma shielding, cure characteristics, and mechanical properties of natural rubber (NR) system with addition of oxides such as: iron (II, III) oxide (Fe₃O₄), tungsten (III) oxide (W₂O₃), or bismuth (III) oxide (Bi₂O₃) were studied for potential replacement of flexible lead (Pb), and introduced as gamma-shielding materials, to minimize risks caused by Pb. The results showed that increase in the content of oxides such as Fe₃O₄, W₂O₃, or Bi₂O₃ from 0 to 100, 300, and 500 parts/100 parts of rubber by weight (phr) increased the gamma attenuation coefficients, tensile modulus at 100% elongation, and hardness (Shore A), though they reduced the tensile strength and elongation-at-break. The composites also underwent thermal aging tests at 70 °C for 96 h. The results indicated slight reduction in the overall tensile properties. Specifically, for NR composites with 300 or 500 phr of Bi₂O₃, the mass attenuation coefficients (μ _m) of these composites were the highest among other composites and even higher than lead sheets that were measured using the same set-up. The outcome of the results imply great possibilities of replacing hazardous lead-containing gamma-shielding materials with the investigated composites, while still providing safe and efficient gamma-shielding properties for the users.     

Tumor-Promoting Activity and Proteomic Profiling of Cisplatin/Oxaliplatin-Derived DAMPs in Cholangiocarcinoma Cells

Damage-associated molecular patterns (DAMPs) are well recognized as the molecular signature of immunogenic cell death (ICD). The efficacy of drug-induced ICD function may be impacted by the precise ratio between immunostimulatory and immunoinhibitory DAMPs. Tumor-derived DAMPs can activate tumor-expressed TLRs for the promotion of tumor cell motility, invasion, metastatic spread and resistance to chemotherapeutic treatment. Herein, drug-induced DAMPs’ expression and their role in tumor progression are utilized as one crucial point of evaluation regarding chemotherapeutic treatment efficacy in our study. Cisplatin and oxaliplatin, the conventional anticancer chemotherapy drugs, are emphasized as a cause of well-known DAMPs’ release from cholangiocarcinoma (CCA) cells (e.g., HSP family, S100, CRT and HMGB1), whereby they trigger Akt, ERK and Cyclin-D1 to promote tumor activities. These findings strengthen the evidence that DAMPs are not only involved in immunomodulation but also in tumor promotion. Therefore, DAMP molecules should be considered as either targets of cancer treatment or biomarkers to evaluate treatment efficacy and tumor recurrence.     

Novel Recovery of Nano-Structured Ceria (CeO(2)) from Ce(III)-Benzoxazine Dimer Complexes via Thermal Decomposition

N,N-bis(2-hydroxybenzyl)alkylamines, benzoxazine dimers, are the major product produced from benzoxazine monomers on mono-functional phenol by the one step ring opening reaction. Due to the metal responsive property of benzoxazine dimers, in this present work, N,N-bis(5-methyl-2-hydroxybenzyl)methylamine (MMD), N,N-bis (5-ethyl-2-hydroxybenzyl)methylamine (EMD), and N,N-bis(5-methoxy-2-hydroxybenzyl) methyl amine (MeMD), are considered as novel ligands for rare earth metal ion, such as cerium(III) ion. The complex formed when the clear and colorless solutions of cerium nitrate and benzoxazine dimers were mixed, results in a brown colored solution. The metal-ligand ratios determined by the molar ratio and the Job's methods were found to be in a ratio of 1:6. To clarify the evidence of the complex formation mechanism, the interactions among protons in benzoxazine dimers both prior to and after the formation of complexes were determined by means of (1)H-NMR, 2D-NMR and a computational simulation. The single phase ceria (CeO(2)) was successfully prepared by thermal decomposition of the Ce(III)-benzoxazine dimer complexes at 600 °C for 2 h, was then characterized using XRD. In addition, the ceria powder investigated by TEM is spherical with an average diameter of 20 nm.     

Electrolyte materials for solid oxide fuel cells derived from metal complexes: Gadolinia-doped ceria

Gadolinia doped ceria (GDC) powders with different gadolinium contents were successfully prepared by the thermal decomposition of ceria complexes. All the calcined powder samples were found to be ceria-based solid-solutions having a fluorite-type structure. The powders were cold-isostatically pressed and sintered in air at 1500 °C for 5 h to attain a sintered density of about 90% of its theoretical value. The electrical conductivity of the GDC pellets in air was studied as a function of temperature in the 225–700 °C range, by using two-probe electrochemical impedance spectroscopy measurements. The highest total conductivity (σ_600 °C = 0.025 S/cm) was found for the Ce_0.85Gd_0.15O_1.925 composition.     

Mossar: motion segmentation by using splitting and remerging strategies

This paper presents a novel approach for motion segmentation by using strategies of splitting and remerging. The presented approach, Mossar, hybridizes two existing ones to obtain their potential advantages while covering weaknesses: (1) velocity-based, one of the most widely used approaches that has fairly low accuracy but provides computational simplicity and (2) graph-based, a state-of-the-art approach that provides outstanding accuracy, yet bears high computational complexity and a burden in setting of thresholds. An initial set of key frames is generated by a velocity-based splitting process and then fed into a graph-based remerging process for refinement. We present mechanisms that improve key-frames capturing in the velocity-based approach as well as details on how the graph-based approach is modified and later applied to remerging. The proposed approach also allows users to interactively add or reduce the number of key frames to control segmentation hierarchy without the need to change threshold values and re-run segmentation, as usually done in existing approaches. Our experimental results show that the presented hybrid approach, compared to both velocity-based and graph-based, demonstrates superior performance in terms of accuracy and in comparison to graph-based, our approach has not only less complexity but also a lesser number of thresholds, the values of which can be much more simply determined.     

Development of tunable biodegradable polyhydroxyalkanoates microspheres for controlled delivery of tetracycline for treating periodontal disease

This article was aimed at preparation and characterization of drug delivery carriers made from biodegradable polyhydroxyalkanoates (PHAs) for slow release of tetracycline (TC) for periodontal treatment. Four PHA variants; polyhydroxybutyrate (PHB), poly(hydroxybutyrate‐co‐hydroxyvalerate) with 5, 12, and 50% hydroxyvalerate were used to formulate TC‐loaded PHA microspheres by double emulsion‐solvent evaporation method. We also compared the effect of different molecular weight (M_w) of polyvinyl alcohol (PVA) acting as surface stabilizer on particle size, drug loading, encapsulation efficiency, and drug release profile. The TC‐loaded PHA microspheres exhibited microscale and nanoscale spherical morphology under scanning electron microscopy. Among formulations, TC‐loaded PHB:low M_w PVA demonstrated the highest TC loading with slow release behavior. Our results showed that the release rate from PHA microspheres was influenced by both the type of PHA and M_w of PVA stabilizer. Lastly, TC‐loaded PHB microspheres showed efficient killing activity against periodontitis‐causing bacteria, suggesting its potential application for treating periodontal disease. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44128.     

Processing of Kaolinite and Alumina Loaded in Natural Rubber Composite Foams

Composite natural rubber foams were successfully prepared from the vulcanization of natural rubber in a sulfur curing system. The natural rubber matrix phase was added with chlorinated polyethylene, kaolinite, and alumina. The morphology of natural rubber composite foams was altered when a gas was generated at the vulcanization temperature of 150°C to obtain open and closed cell structures. Furthermore, the kaolinite and alumina reinforced the mechanical properties and increased the thermal resistance of the composite foams. The composite foams were light in weight and had good thermal, mechanical, and electrical properties, suitable for energy absorption, thermal insulation, and structural uses.     

A 10.7-MHz fully balanced,high-Q, 87-dB-dynamic-range current-tunable Gm-C bandpass filter

A 10.7-MHz fully balanced, high-Q, wide-dynamic-range current-tunable Gm-C bandpass filter is presented. The technique is relatively simple based on two fully balanced components, i.e. an adder and a low-Q-based bandpass filter. The Q factor is approximately equal to a typically high and constant value of a common-emitter current gain (β) and is, for the first time, independent of variables such as a center frequency. Possible solutions for good stability of the Q factor with temperature are suggested. Not only can the need for additional Q-tunable circuits be greatly reduced, the sensitivity of the Q factor can be greatly improved. Sensitivities of either the Q factor or the center frequency are constant between 1 and −1 and are no longer strongly affected by the Q factor or variables. As a simple example at 10.7 MHz, the paper demonstrates the high-Q factor of 121, the low total output noise of 5.303 μV_rms, the 3rd-order intermodulation-free dynamic range (IMFDR₃) of 74.45 dB and the wide dynamic range of 87.45 dB at 1% IM₃. The center frequency is current tunable over three orders of magnitude. Comparisons to other 10.7-MHz Gm-C approaches are also included.