916 research outputs found
The Enantioselective Organocatalytic 1,4-Addition of Electron-Rich Benzenes to α,β-Unsaturated Aldehydes
The first enantioselective organocatalytic alkylation of electron-rich benzene rings with α,β-unsaturated aldehydes has been accomplished. The use of iminium catalysis has provided a new strategy for the enantioselective construction of benzylic stereogenicity, an important chiral synthon for natural product and medicinal agent synthesis. The (2S,5S)-5-benzyl-2-tert-butylimidazolidinone amine catalyst has been found to mediate the conjugate addition of a wide variety of substituted and unsubstituted anilines to unsaturated aldehydes. A diverse spectrum of aldehyde substrates can also be accommodated in this new organocatalytic transformation. While catalyst quantities of 10 mol % were generally employed in this study, successful alkylations conducted with catalyst loadings as low as 1 mol % are described
R&D results on a CsI-TTGEM based photodetector
The very high momentum particle identification detector proposed for the
ALICE upgrade is a focusing RICH using a C4F10 gaseous radiator. For the
detection of Cherenkov photons, one of the options currently under
investigation is to use a CsI coated Triple-Thick-GEM (CsI-TTGEM) with metallic
or resistive electrodes. We will present results from the laboratory studies as
well as preliminary results of beam tests of a RICH detector prototype
consisting of a CaF2 radiator coupled to a 10x10 cm2 CsI-TTGEM equipped with a
pad readout and GASSIPLEX-based front-end electronics. With such a prototype
the detection of Cherenkov photons simultaneously with minimum ionizing
particles has been achieved for the first time in a stable operation mode
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Characterization of fluid flow in a microchannel with a flow disturbing step
This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.The flow around a flow-disturbing step in a rectangular microchannel is studied by measuring the
wall shear rate along the channel, using the electrodiffusion technique and by determining the velocity field
using the -PIV method. A parametric study based on the Design of Experiments (DOE) and the Response
Surface Methodology (RSM) was then performed, and the effect of key design parameters on the flow characteristics
was numerically investigated using CFD simulations. The computational results are in excellent agreement
with the corresponding experimental ones. The CFD simulations cover both the laminar and the turbulent
flow regime. It was revealed that in both flow regimes the step height has a major influence on the recirculation
length. However, the Reynolds number (Re) value affects the recirculation length only in the laminar region,
while the step length seems to have no significant effect compared to the Re and the step height. Finally, new
correlations are proposed predicting the length of the bottom recirculation zone with reasonable accuracy and
can be used as rough guidelines for the design of microdevices
Effect of Bio-degradation and Non Degradable Substances in Environment
Non-Biodegradable substances produce the greenhouse gasses, methane and carbon dioxide. Growing plants and trees on top of a landfill, a process known as ‘Phyto capping\u27, could reduce the production and release of these gasses. In certain parts of the world, it remains the most economical and simplest method of waste disposal. Biodegradation of organic matter in a landfill site occurs most rapidly when water comes into contact with the buried waste. An important step in the drive is to remove environmentally harmful materials from waste streams and drinking water. A synthetic clay known as swelling mica has the ability to separate ions of radium, a radioactive metal, from the water. The finding could have implications for radioactive and hazardous waste disposal, particularly in the cleanup of mill tailings left over from the processing of uranium for the nation\u27s nuclear industry. The tailings contain radium and heavy metals
Introduction About Child Health Status in India
Child health is a multifaceted problem which is directly linked to a large extent to mother’s health conditions, safe delivery conditions, socio-economic conditions of the family and the health care system. Over the time, the nation has implemented a number of child-centric programs, the poor health status of women and children in terms of high mortality and morbidity was another health priority in this country. Health facilities like hospitals and health centers were established for providing Maternal and Child Healthcare through antenatal, intra-natal and postnatal services. In addition, a number of special programs and schemes like immunization against vaccine-preventable diseases, nutrition interventions like iron and folic acid distribution and vitamin A supplementation, diarrheal disease control through Oral Rehydration Therapy (ORT), Acute Respiratory Infection (ARI) control program etc. were implemented over the past. In order to, ensure maximum benefit from these programs and to provide services in an integrated manner to these vulnerable groups strong monitoring system required
CFD Modelling of Hydrodynamics and Heat Transfer in Channels of a PHE
Plate Heat Exchangers (PHEs) are one of the most efficient types of contemporary heat exchangers with intensified heat transfer. They are commonly used in process industries due to their compactness, lower weight and cost, smaller space for installation and servicing compared to conventional shell-and-tube heat exchangers. Heat transfer in PHEs takes place in channels of complex geometry formed by corrugated plates placed abutting. The flow in such channels can be very complicated due to breakup and reattachment of the boundary layer, secondary flows and the small hydraulic diameter of the flow passages. The aim of this work is to compare a well-established and validated CFD code both with results obtained from an experimental PHE model using a corrugated plate commonly used in industrial applications and with existing correlations. The results show that CFD simulation can predict heat transfer rate and fluid flow behaviour in a range of Re numbers (8,900 to 27,650), with discrepancies up to 1 % and 6 % in terms of outlet temperature and pressure drop respectively. Modelling of the flow inside a single corrugation also allows for computation of the wall shear stress distribution which can be very useful in PHE applications where fouling is of particular importance
Impact of Medical Education Trend in Community Development
Problem-based learning has been described as one of the most significant developments in medical education. The trend of medical education plays a vital role in determining the success of universal health coverage in India. The motto of health education is community-based training, where students are placed in the community and learn by delivering the care using the existing health services
Thermophysical, Acoustical, Spectral and DFT Study of Intermolecular Interactions of Terpinolene with Cresols.
Abstract Densities and speed of sound were measured experimentally for binary mixtures of terpinolene with cresols (o-cresol, m-cresol, p-cresol) at three different temperatures 303.15, 308.15 and 313.15K at atmospheric pressure. From primary physical properties, some secondary properties like molar volume , excess molar volume , partial molar volume , excess partial molar volume , apparent molar volume , deviation in speed of sound , isentropic compressibility , deviation in isentropic compressibility , acoustical impedance , deviation in acoustical impedances , intermolecular free length , partial molar isentropic compression , excess partial molar isentropic compression and apparent molar isentropic compression were calculated. Infinite dilution apparent molar volume , infinite dilution apparent molar isentropic compression , empirical parameters , and , of the Redlich-Rosenberg-Mayer equation with the limiting apparent molar expansibility were also calculated. Some theoretical speed of sound calculating relations such as Nomoto relation , Ideal mixture relation , Junji relation and Free length theory relation were also calculated with their standard deviation . All the calculated values of excess/deviation properties were fitted with the fourth order Redlich-Kister polynomial equation and their standard deviation values were also calculated. FT-IR spectral analysis of binary mixtures at 4:1, 1:1 and 1:4 composition ratios were carried out at 298.15K. Computational calculations such as optimization of pure and binary mixtures in gas phase, bond length, Mulliken charges, theoretical vibrational frequencies and NBO calculations on basis of the DFT (Density Function Theory) were also carried out. The results were discussed in term of presence of intermolecular interactions, types, strength and behavior with change of temperatures and cresol components in binary mixtures
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