Protein kinase C in platelets of depressed patients

Though described in 1769, the etiology of Zenker's diverticulum remains unclear. Various primary esophageal motor disorders have been proposed, but no consistent manometric pattern or anatomic etiology has been uniformly recognized. An association with clinical neurologic disease at our institution prompted a review of 12 cases of Zenker's diverticulum in patients over 60 years of age, treated in the last 8 years. Nine patients (75%) underwent cricopharyngeus myotomy and diverticulectomy, with uniformly good results. Ten patients (83%) had an associated neurologic disorder, substantiated by cranial CT or MRI, in most cases. A wide range of neurologic problems were identified, but a strong trend toward brainstem or basilar lesions was present. As expected, the etiology of the neurologic abnormality in most patients in this group was cerebrovascular disease, but two patients had peripheral neuropathies. We suggest that the etiology of Zenker's diverticulum in the elderly may be neurologic in origin. Esophageal motor disorders, including incomplete upper esophageal sphincter opening and increased hypopharyngeal pressures, which may result in Zenker's diverticulum, may be a manifestation of central or peripheral neurologic disease in the elderly.     

Accelerated weathering properties of compatibilized composites made from recycled HDPE and nonmetallic printed circuit board waste

The main aim of this work is to examine the influence of the contents of nonmetallic printed circuit board (PCB) waste component on the photodegradation of recycled high‐density polyethylene (rHDPE) composites. The properties tested were chemical changes, flexural properties, color stability, water absorption, leaching properties, and crystallinity changes of the composites after exposure to 2,000 h of accelerated weathering. Surface degradation for composites with nonmetallic PCB was less compared to unfilled rHDPE mainly because glass fibers covered almost the whole surface of specimens, acting as a protective layer, thus, slowing down the photodegradation reaction. Incorporation of compatibilizer in rHDPE/PCB composites had played an important role in resisting degradation due to UV exposure. All the composite samples became lighter in the early stages of weathering exposure; however, compatibilized composites showed less lightening and reduction on strength and modulus. Carbonyl index increases with exposure time indicating that the oxidation reaction continuously occurred during the aging process. Incorporation of compatibilizer had successfully reduced the water absorption uptake by the composites and effectively delayed some degradation properties of weathering. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43110.     

Microstructure and mechanical properties of mechanically alloyed and spark plasma sintered amorphous–nanocrystalline Al65Cu20Ti15 intermetallic matrix composite reinforced with TiO2 nanoparticles

Multiphase Al₆₅Cu₂₀Ti₁₅ intermetallic alloy matrix composite, dispersed with 10 wt.% of TiO₂ nanoparticles, has been processed by mechanical alloying, followed by spark plasma sintering under pressure in the temperature range of 623–873 K. Differential scanning calorimetry and X-ray diffraction suggest that equilibrium crystalline phases evolve from the amorphous or intermediate crystalline phases. Transmission electron microscopy shows that the composite sintered at 873 K has partially amorphous microstructure, with dispersion of equilibrium, crystalline, intermetallic precipitates of Al₅CuTi₂, Al₃Ti, and Al₂Cu of 25–50 nm size, besides the TiO₂. The composite sintered at 873 K exhibits little porosity, hardness of 5.6 GPa, indentation fracture toughness in the range of 3.1–4.2 MPa√m, and compressive strength of 1.1 GPa. Indentation crack deflection by TiO₂ particle aggregates causes increase in fracture resistance with crack length, and suggests R-curve type behaviour. The study provides guidelines for processing high strength amorphous–nanocrystalline intermetallic composites based on the Al–Cu–Ti ternary system.     

Effect of strontium doping on structural and dielectric behaviour of barium titanate nanoceramics

ABSTRACT

Barium strontium titanate (Ba_(1?x)Sr_xTiO₃ where, x?=?0.0, 0.2, 0.3, 0.4 and 0.5) nanoparticles have been successfully synthesised by sol–gel method and characterised thoroughly. With the increase in Sr concentration (x?>?0.3), the symmetry of the crystal structure changed from tetragonal to cubic phase. The dielectric behaviour of the ceramic nanoparticles was evaluated using impedance analyser with an operating frequency of 1?Hz to 1?MHz. A very high dielectric constant 4915 was obtained for Ba_0.7Sr_0.3TiO₃ at 1?Hz frequency with low dielectric loss of 1.91, which showed very good value than the one previously reported. The density of the material was found to be >98% of theoretical density. Dielectric constants were measured by varying the temperature from 35 to 150°C and the Curie temperatures were also evaluated. The small amount of Sr doping was beneficial for obtaining high dielectric constant material which can be used in various electronic applications.     

Wavelength dependent laser-induced etching of Cr-O doped GaAs: Morphology studies by SEM and AFM

The laser induced etching of semi-insulating GaAs 〈100〉 is carried out to create porous structure under super- and sub-bandgap photon illumination (h v). The etching mechanism is different for these separate illuminations where defect states play the key role in making distinction between these two processes. Separate models are proposed for both the cases to explain the etching efficiency. It is observed that under sub-bandgap photon illumination the etching process starts vigorously through the mediation of intermediate defect states. The defect states initiate the pits formation and subsequently pore propagation occurs due to asymmetric electric field in the pore. Formation of GaAs nanostructures is observed using scanning electron (SEM) and atomic force microscopy (AFM).     

Preparation of diamond like carbon thin film on stainless steel and its SEM characterization

We report the formation of a very smooth, continuous and homogeneous diamond-like carbon DLC thin coating over a bare stainless steel surface without the need for a thin Si/Cr/Ni/Mo/W/TiN/TiC interfacial layer. As confirmed by the field-emission scanning electron microscopy, good adhesion is achieved as characterized by (i) the formation of a smooth, continuous film with no pores, (ii) a significant reduction of oxygen in the interfacial layer, and (iii) the development of rich carbon content at the top surface. Thickness measurements by cross-sectional secondary-emission microscopy showed that the DLC coating is essentially a 2-dimensional material.     

Genotoxicity of silver nanoparticles in Allium cepa

Potential health and environmental effects of nanoparticles need to be thoroughly assessed before their widespread commercialization. Though there are few studies on cytotoxicity of nanoparticles on mammalian and human cell lines, there are hardly any reports on genotoxic and cytotoxic behavior of nanoparticles in plant cells. This study aims to investigate cytotoxic and genotoxic impacts of silver nanoparticles using root tip cells of Allium cepa as an indicator organism. A.cepa root tip cells were treated with four different concentrations (25, 20, 75, and 100 ppm) of engineered silver nanoparticles (below 100 nm size) dispersion, to study endpoints like mitotic index, distribution of cells in mitotic phases, different types of chromosomal aberrations, disturbed metaphase, sticky chromosome, cell wall disintegration, and breaks. For each concentration five sets of microscopic observations were carried out. No chromosomal aberration was observed in the control (untreated onion root tips) and the mitotic index (MI) value was 60.3%. With increasing concentration of the nanoparticles decrease in the mitotic index was noticed (60.30% to 27.62%). The different cytological effects including the chromosomal aberrations were studied in detail for the treated cells as well as control. We infer from this study that silver nanoparticles could penetrate plant system and may impair stages of cell division causing chromatin bridge, stickiness, disturbed metaphase, multiple chromosomal breaks and cell disintegration. The findings also suggest that plants as an important component of the ecosystems need to be included when evaluating the overall toxicological impact of the nanoparticles in the environment.