Effect of Ferroelectric Nanopowder on Electrical and Acoustical Properties of Cholesteric Liquid Crystal

Ferroelectric nano-materials are very sensitive to several external stimuli and have attracted great deal of attention due to their property of improving various properties such as photoluminescence, higher polarization, fast response time, low operating voltage and improved conductivity. For enhancing the physical properties, a proper selection of nano-materials for liquid crystals depends upon various factors such as size, shape, preparation methods, surfactant concentration and amount of doping materials. In the present study an attempt is made to study  electrical and acoustical properties of cholesteric liquid crystal after dispersing ferroelectric nano-powder of Barium Titanate (BaTiO3). In addition with this particle size and surface area of pure and nono-particle dispersed liquid crystal were also measured. Our investigation shows increase in Rao’s constant or molar sound velocity, which indicates increase in molecular density indicating a close packing of the material. The measurement of dielectric relaxation at different frequencies gives information about the dynamics of polar groups and molecular motion

AUTOMOTIVE SEAT DESIGN CONSIDERATIONS THROUGH COMPARATIVE STUDY OF ANTI WHIPLASH INJURY CRITERIA

Although whiplash injuries can occur in any kind of crash, an occupant's chances of sustaining this type of injury are greatest in rear-end collisions. When a vehicle is struck from behind, typically several things occur in quick succession to an occupant of that vehicle. An objective for this research paper is to compare the relation between the anti whiplash criteria, their effectiveness & possibility of verifying the defined performance limits by various consumer rating groups, insurance agencies, and regulatory authorities. This research paper describes work done by different OEMs worldwide on Whiplash injuries. It focuses on methodologies, test requirements; instrumentation and setup defined in protocol by different groups on passive safety i.e. GTR7, EuroNCAP, IIHS and RCAR. This research was carried with methodology / process specified in GTR 7 i.e. use of dynamic sled testing and static measurements by R point and H point methods using HPM with HRMD and other different protocols. Lastly we observed significant contribution of seat backset parameter to whiplash injuries in dynamic sled test. Means higher the backset more is relative head rotation v/s torso leading to whiplash injuries. Seat system design parameters such as R / H point, Seating Torso angle and Head restraint profile, seat geometry govern Backset dimension

Silica nanofibrous membranes for the separation of heterogeneous azeotropes

Nanofibrous materials produced through electrospinning are characterized by a high porosity, large specific surface area, and high pore interconnectivity and, therefore, show potential for, e.g., separation and filtration. The development of more inert nanofibers with higher thermal and chemical resistance extends the application field to high-end purification. Silica nanofibrous membranes produced by direct electrospinning of a sol-gel solution without a sacrificing carrier, starting from tetraethoxysilane, meet these challenging requirements. After electrospinning the membrane is highly hydrophobic. Storage under dry conditions preserves this property. Oppositely, a superhydrophilic membrane is obtained by storage under high humidity (month scale). This switch is caused by the reaction of ethoxy groups, present due to incomplete hydrolysis of the precursor, with moisture in the air, resulting in an increased amount of silanol groups. This transition can be accelerated to hour scale by applying a heat treatment, with the additional increase in cross-linking density for temperatures above 400 degrees C, enabling applications that make use of hydrophobic and hydrophilic membranes by tuning the functionalization. It is showcased that upon designing the water repellent or absorbing nature of the silica material, fast gravity-driven membrane separation of heterogeneous azeotropes can be achieved

Effect of aging on silica aerogel properties

Silica aerogels’ unique physical and chemical properties make them fascinating materials for a wide variety of applications. In addition to hydrophobization by silylation, aging is very important in the synthesis of silica aerogel by ambient pressure drying. Here we systematically study the effect of aging on the physico-chemical properties of silica aerogel with emphasis on ambient dried materials. Silica gels were aged for different times and at different temperatures in their gelation liquid (without solvent exchange), hydrophobized in hexamethyldisiloxane and subsequently dried either at ambient pressure or from supercritical CO2. Dynamic oscillatory rheological measurements demonstrate that aging reinforces the alcogels, particularly at high strain. The specific surface area decreases with increasing aging time and temperature as a consequence of Ostwald ripening processes during aging. With increasing aging time and temperature, the linear shrinkage and bulk density decrease and the pore size and pore volume increase for the ambient dried gels, but remain nearly constant for supercritically dried gels. Small-Angle X-ray scattering does not detect significant structural changes at length scales smaller than about hundred nanometers, but hints at systematic variations at larger length scales. The findings of this study highlight the importance of aging to increase the ability of the gel particle network to withstand irreversible pore collapse during ambient pressure drying

Vertical Distribution of Aerosols during Deep-Convective Event in the Himalaya Using WRF-Chem Model at Convection Permitting Scale

The Himalayan region is facing frequent cloud bursts and flood events during the summer monsoon season. The Kedarnath flooding of 2013 was one of the most devastating recent events, which claimed thousands of human lives, heavy infrastructure, and economic losses. Previous research reported that the combination of fast-moving monsoon, pre-existing westerlies, and orographic uplifting were the major reasons for the observed cloud burst over Kedarnath. Our study illustrates the vertical distribution of aerosols during this event and its possible role using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) simulations. Model performance evaluation shows that simulations can capture the spatial and temporal patterns of observed precipitation during this event. Model simulation at 25 km and 4 km horizontal grid resolution, without any changes in physical parameterization, shows a very minimal difference in precipitation. Simulation at convection-permitting scale shows detailed information related to parcel motion compared to coarser resolution. This indicates that the parameterization at different resolutions needs to be further examined for a better outcome. The modeled result shows changes of up to 20–50% in the rainfall over the area near Kedarnath due to the presence of aerosols. Simulation at both resolutions shows the significant vertical transport of natural (increases by 50%+) and anthropogenic aerosols (increases by 200%+) during the convective event, which leads to significant changes in cloud properties, rain concentration, and ice concentration in the presence of these aerosols. Simulations can detect changes in important instability indices such as convective available potential energy (CAPE), convective inhibition energy (CIN), vorticity, etc., near Kedarnath due to aerosol–radiation feedback

A randomized control trial comparing outcome after stented and nonstented Anderson-Hynes dismembered pyeloplasty

Aim: The aim of the study was to compare the efficacy and postoperative complications of stented and nonstented open pediatric dismembered pyeloplasty for ureteropelvic junction (UPJ) obstruction. Settings and Design: A balanced, parallel group, prospective randomized controlled trial comparing stented and nonstented Anderson-Hynes Dismembered Pyeloplasty. Subjects and Methods: It included 42 children who required Anderson-Hynes dismembered pyeloplasty for UPJ obstruction (UPJO). Patients were randomized into stented (double “J” [DJ] stent) and nonstented pyeloplasty groups. The intraoperative and postoperative course was compared. Both groups were analyzed for problems such as dysuria, frequency, pain, hematuria and urinary tract infection, and postoperative renal status. Statistical Analysis: Mann–Whitney U-test, Fisher's exact test, Student's t-tests, and Chi-squared test were used. Results: Surgical duration was significantly shorter for the nonstented group as compared to the stented group (60.4 ± 6.49 min vs. 78.9 ± 8.17 min). The intraoperative negotiation of DJ stent was troublesome in 21.7% patients belonging to the stented group. The hospital stay was comparable in both groups (4.67 ± 1.9 vs. 4.28 ± 0.67 days). Patients in stented group had experienced dysuria, loin pain, lower abdominal spasmodic pain, and frequency significantly higher than nonstented group. However, the other problems such as fever, hematuria, and urinary tract infections were more common in stented group, but the difference was not statistically significant. There was no difference in resolution of hydronephrosis in both groups. Conclusions: There is no statistically significant difference in resolution of hydronephrosis following nonstented or stented dismembered pyeloplasty in children with UPJO. However, the patient is more symptomatic due to stent in the postoperative period