Electrical stimulation of the paralyzed orbicularis oculi in rabbit.

Dysfunction of the seventh cranial nerve often results in facial paralysis and loss of the ability to blink the eye, which can lead to corneal scarring, diminished vision, and potential loss of the eye. This study investigated the potential of electrical stimulation of the orbicularis oculi muscle as a means of restoring blink function. An animal model of orbicularis paralysis was created by sectioning the seventh cranial nerve in rabbit. Twenty paralyzed and five normal rabbits were acutely implanted with a subcutaneous stimulating electrode near the margin of the upper eyelid. Biphasic current controlled stimulation pulses were delivered between implanted contacts at the medial and lateral edges of the eyelid. Strength-duration curves for lid twitch threshold were generated, and quantitative measurements of lid closure were made for systematically varied parameters including pulse amplitude, pulse width, number of pulses delivered, and duration of paralysis prior to stimulation. Normal rabbits achieved a greater degree of lid closure due to electrical stimulation than rabbits that had been surgically paralyzed. Of rabbits that had been paralyzed, those demonstrating evidence of at least partial reinnervation achieved a greater degree of lid closure than those demonstrating persistent denervation. Trains of 10 ms biphasic pulses delivered at 50 Hz were found to be the most effective means of eliciting lid closure for the range of parameters tested.     

Evidence that L-sucrose is resistant to hydrolysis catalyzed by jejunal brush border enzymes

The sucrase-isomaltase complex of the intestinal brush border membrane (BBM) catalyzes the hydrolysis of sucrose. The stereospecificity of this enzyme, however, is not known. To investigate this, BBM of hamster jejunum was incubated with D-sucrose or L-sucrose, and the reaction mixture was analyzed using a gas-liquid chromatograph. It was found that D-sucrose was hydrolyzed to its monomers, but L-sucrose remained unhydrolyzed. It is concluded that the sucrase-isomaltase of intestinal BBM of hamster jejunum does not hydrolyze L-sucrose and therefore this enzyme is stereospecific.     

Study on the fatty acid composition during germination of peanuts treated with growth regulators

The fatty acid metabolism during germination of a special variety of peanuts treated with growth regulators, viz., GA, AA, Suc, Sul, MH and DW have been studied in sterile media for 1, 3, 6, 10, 14 and 18 days. No marked variation in the oil content of the control and the treated seeds is found during the initial period of germination. Initial growth is explained on the basis of energy supplied by the FFA and carbohydrates (as they are found decreasing during the 24 hr of germination). Practically no accumulation of FFA is observed throughout the complete period of germination. The mode of utilization of neutral oil with the period of germination is correlated with growth. The varied effect of growth regulators on the fat metabolism is explained assuming their various effects on mitochondria, the enzyme center, and on the process of photosynthesis. Active metabolism is marked from the sixth day of germination for both treated and control seeds. From the beginning of germination, interconversion of fatty acids is marked. Metabolism of fatty acids during germination is reported with the preferential utilization of 18:2 acid.     

Comparison of titanium silicide and carbide reinforced in situ synthesized TiAl composites and their mechanical properties

This study explored a synthesizing route involving in situ development of reinforcements of titanium silicides in a series of TiAl-based matrices. The main features of this processing route are: (1) Incorporating a small quantity of mechanically alloyed Ti–Al–Si and Ti–Al–Si–C powders, referred to as precursors, into Ti–Al–X (X stands for Cr, Mn, Nb, or their combination) powder mixtures that act as matrices; and (2) Hot isostatic pressing (HIPing) of the cold compacted mixture at a temperature of 1100 °C for 4 h. A series of composites based on different Ti–Al–X matrix were synthesized. The structural evolution in these composites was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The mechanical properties and compression tests at room and elevated temperatures (600 °C and 800 °C) have been investigated. In addition, the influence of alloying elements in the matrix has been evaluated from their stress–strain responses.     

Clay induced thermoplastic crystals in thermoset matrix: Thermal,Dynamic mechanical,and morphological analysis of clay/nylon‐6‐epoxy nanocomposites

A novel procedure to synthesize in situ clay/nylon‐6 composite suspension was explored via anionic solution polymerization. The suspension was efficiently blended with water‐based epoxy resin using mechanical stirrer at room temperature. Hence, a 3‐component coating system was obtained consisting of nano‐clay, nylon‐6 and epoxy resin. Large number of coatings and films were prepared with variation in clay and nylon‐6 loading. Concentration of clay was found to have profound effect on crystallinity of nylon‐6, thereby affecting the overall properties of clay/nylon/epoxy composite. All the films were characterized for thermal and dynamic mechanical behavior using differential scanning calorimeter (DSC) and dynamic mechanical analysis (DMA). Lower amount of clay was found to increase the crystallinity of nylon‐6 which in turn increased the plasticization of epoxy resin indicated by reduction in T_g. A multiphase morphology with distinct amorphous and crystalline zones was observed under scanning electron microscopy (SEM). A remarkable symmetrical morphology with branched dendritic crystal structure was observed for few of the clay/nylon/epoxy system. POLYM. COMPOS., 37:2206–2217, 2016. © 2015 Society of Plastics Engineers     

Micropolar couple stress thermofluidics and entropy in Forchheimer channel

This paper presents an analysis of the entropy generated in thermofluidic configuration involving micropolar couple stress fluid flow inside a Forchheimer channel. The channel is composed of a porous medium trapped between two parallel permeable plates separated by distance H through which the fluid can be sucked out/injected in. One of the plate bears a constant temperature and other is subjected to a uniform heat flux. A Cartesian coordinate system is chosen to model the flow configuration. The nondimensional nonlinear governing equations are solved by the differential transform method and Runge–Kutta–Fehlberg method to ascertain the accuracy of the results. Both the methods do match to the order of 10⁻⁶ for the quantities velocity, microrotation, and temperature. These quantities and their gradients are required to the compute entropy generation number. The effects of the parameters on entropy generation and Bejan number are discussed through various plots.     

Self-healing of tightly focused scalar and vector Bessel-Gauss beams at the focal plane

The property of self-healing at the focal plane for both scalar and vector Bessel-Gauss (BG) beams is investigated in the tight focusing condition. For the BG beam, which is partially obstructed at the pupil plane, the spatial intensity distribution at the focal plane is well recovered. Furthermore, recovery of not only intensity but also polarization distribution is observed for an obstructed vector BG beam. This self-healing effect for both the intensity and polarization components is recognized even when the half of the beam is obstructed by a semicircular obstacle. The effect of the size of the obstacle on recovery of polarization and intensity distribution is studied. The role of the beam size at the pupil plane is also discussed.     

The inhibitory effect of angiotensin II on stimulus-induced release of cAMP is augmented in the genetically hypertensive rat kidney

In the present study, with isolated perfused kidneys, we evaluated whether angiotensin II (Ang II) inhibits stimulus-induced release of adenosine 3',5'-cyclic monophosphate (cAMP) and whether this effect is augmented in spontaneously hypertensive rats (SHR). The basal release of cAMP (in venous effluent) in the presence of captopril (1 mumol/l) and a phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (10 mumol/l), was significantly (P < .05) higher in the SHR (n = 20) than in Wistar-Kyoto (WKY) kidneys (n = 18) although perfusion pressures were not significantly different in the two strains. Isoproterenol infusions (ISO; 0.3, 1 and 3 mumol/l) significantly and similarly increased cAMP release in both WKY (n = 5; P < .01) and SHR (n = 6; P < .01) kidneys. A time-related attenuation of the cAMP response to ISO in both strains was observed in these experiments. In control experiments, Ang II (3 and 10 ng/min), by itself, did not significantly alter basal cAMP release in either strain but raised perfusion pressure in both SHR and WKY kidneys. In a separate set of experiments, Ang II significantly (3 ng/min: P < .05; 10 ng/min: P < .01) inhibited ISO-induced increases in release of cAMP from SHR kidneys (n = 8), whereas cAMP release in response to ISO in WKY kidneys (n = 8) was not affected by Ang II (3 and 10 ng/min). In the same experiments, ISO produced small but significant decreases in perfusion pressure in WKY (P < .01) but not in SHR. These data clearly and directly demonstrate that ISO-induced increases in cAMP in the renal vasculature are similar in SHR and WKY rats; however, Ang II exerts a much greater negative influence on the ISO-induced increases in cAMP levels in the renal vasculature of SHR. The augmented inhibition of stimulus-induced cAMP release may be associated with an increased renovascular responsiveness to Ang II in SHR.     

Volume variation of Gruneisen parameters offcc transition metals

The volume variation of the Gruneisen parameters of tenfcc transition metals, up to 40% compression, has been studied on the basis of a model approach proposed by Antonovet al. The results are reasonably good for six metals except for Rh, Ag, Au and Ni when compared with available experimental and other theoretical values. The model requires an appropriate modification for Rh, Ag, Au and Ni.