X-ray structure analysis of 3-chloro-7-hydroxy-4- methyl-chroman-2-one

The title compound crystallizes in the monoclinic space group P21/c, with unit cell parameters a=7.7203(3), b=14.0481(4), c=8.9066(3) Å, â=112.858(5)º, V= 890.11(5) Å3 and Z = 4. The structure has been solved by direct methods and the final R-factor is 0.0433 for 2832 unique reflections. The molecule, as such, is planar and the planarity is confirmed by the magnitude of dihedral angles between the two rings. Extensive Hydrogen-bonding has been observed and chlorine atom is responsible for the formation of trifurcated hydrogen-bond. Trifurcated hydrogen-bond plays a significant role in the design and synthesis of molecules having drug implications

Replication of mixing achieved in large co-rotating screw extruder using a novel laboratory 10-100g minimixer

YesWhen compounding polymers with additives to develop materials at specifications (colouring plastics is the simplest example), the difficulties is in getting the formulation right the first time. Also, when developing completely new materials such as in nanotechnology applications, there is a need to do the initial trials safely and with as small quantities as possible to enable a wide range of experimentation. Wiith traditional applications, often the initial compounding formulation is done using small single or twin screw extruders but with machines that have a fair output to instruct the large scale operation. This step is costly in material wastage and time but more importantly it often does not provide the right formulation which in turn results in bigger wastage cost at the industrial scale before the right formulation is eventually obtained. With the very new material formulations, any reduction in cost of development is always essential. With these aims in mind, we have developed a new minimixer capable of handling tiny quantities of order 10-100g but the minimixer is capable of reproducing the very high mixing conditions experienced in large machines. This invention provides a new opportunity to develop new products quickly, safely and cheaply. The application is not restricted to polymers and can be extended to other soft materials. It has also other spin-offs as a research tool for studying mixing and developing new, more efficient, mixing flows. In this paper we explain the principle of operation we have engineered to produce such intense mixing. Basically, the device is based on combining two opposing flows: a single screw extruder circulation flow with a twin screw extruder mixing flow. The mixing is carried out as a batch but on its completion, the single screw extruder flow is reversed and becomes co-current with the twin extruder flow to enable the discharging of the batch through a die. In the paper we present mixing data obtained with various polymer-additive combinations tested in the minimixer under various conditions of screw speeds, mixing times and temperatures and at the larger scale to underpin the operation of this novel mixer. The quality of mixing of the extrudate was measured using a variety of methods depending on applications: using image analysis of microtome sections of the extrudate or of blown film samples produced from the formulations or measuring electrical properties

Analysis of some antiretroviral drugs in bulk, pharmaceutical formulations and biological fluid

Not availabl

Routing Unmanned Vehicles in GPS-Denied Environments

Most of the routing algorithms for unmanned vehicles, that arise in data gathering and monitoring applications in the literature, rely on the Global Positioning System (GPS) information for localization. However, disruption of GPS signals either intentionally or unintentionally could potentially render these algorithms not applicable. In this article, we present a novel method to address this difficulty by combining methods from cooperative localization and routing. In particular, the article formulates a fundamental combinatorial optimization problem to plan routes for an unmanned vehicle in a GPS-restricted environment while enabling localization for the vehicle. We also develop algorithms to compute optimal paths for the vehicle using the proposed formulation. Extensive simulation results are also presented to corroborate the effectiveness and performance of the proposed formulation and algorithms.Comment: Publised in International Conference on Umanned Aerial System

Prestressed concrete penstock design for water hammer

Thesis (Civ. E.)--Massachusetts Institute of Technology, Dept. of Civil and Sanitary Engineering, 1953.Includes bibliographical references (leaf 38).by Rajnikant Jayachand Kumbhani.Civ.E

Cognitive Rehab Solutions: A computer-assisted cognitive training program

The purpose of this project is to offer a functionally comprehensive application, Cognitive Rehab Solutions (CRS), that is designed for neuropsychologists to deliver restorative cognitive training in areas of attention and memory of persons with brain impairment

Accident Tolerant Fuels Claddings and the Evolution of their Surface Characteristics under Critical Heat Flux

Enhanced Accident Tolerant Fuels (ATFs) systems for light water reactors require higher temperature oxidation resistance in steam environments than the current UO2 – zirconium fuel system. Investigating the ATF materials’ surface properties is needed as they have evidenced to affect the Critical Heat Flux (CHF), which is an important parameter of the thermal-hydraulic performance required to provide safety margins. In this dissertation, the surface properties of FeCrAl alloys (APMT and C26M), Zircaloy-2, Zircaloy-4, and Cr-coating on Zircaloy-4 substrates produced by Physical Vapor Deposition (PVD) and Cold Spray (CS) were investigated according to their chemistry, topography, and wettability. The static contact angle changed from 75º for as-received Zircaloy-4 substrates to almost 20º after the Cr coating deposition. However, a hydrophobic recovery was noticed with environmental surface aging, which was explained by correlating the surface chemistry with surface energy. The surface chemistry of the coated samples and both FeCrAl alloys after CHF was studied thoroughly to understand their evolution at the early stage when subjected to CHF testing. The in-depth surface chemistry analysis evidenced the formation of various oxides that elucidate the rapid response of ATF cladding toward accident scenarios. The evolution of the materials’ surface chemistry also led to a noticeable increase in their wettability, with a slight increase in roughness. The investigation of the materials’ mechanical properties indicated an increase in hardness by 10-15% and an increase in their yield strength, as evidenced by the microindentation and ring compression tests conducted before and after CHF testing

An investigation of the effects of an impact on some of the mechanical properties of aluminum alloy 2014-T6

Static and impact tests were conducted on an Aluminum alloy 2014-T6 specimen. The purpose of this research was to determine the effects of an impact load on some of the mechanical properties of aluminum. The cross section of the specimen measured 4.438 in. by 3.850 in. and it was 12 in. long. It was equipped with a total of four electric resistance gages connected in two pairs. One pair measured longitudinal strain while the other measured transverse strain. Both gages in each pair were mounted on the opposite sides to cancel the bending effect. In the static tests, load was applied with a 300,000 lb. hydraulic testing machine. The longitudinal and transverse strains were read off a Budd strain indicator and recorded against the load. The specimen was then placed in a load frame with a load cell underneath the specimen and a floating head sitting flush on the top. A 2 in. diameter hardened steel ball was welded on the floating head. The ball served as a striking surface for a 107 lb. hammer dropping from a known height. The hammer was guided by two wires, tensioned vertically. An impact load was produced as the hammer, falling freely, struck the floating head of the load frame which contained the specimen. The load was transmitted to the specimen and then to the load cell --Abstract, page ii