On-Board Oxygen Generation Using High Performance Molecular Sieve

The majority of high performance combat aircrafts presently being operated by Indian air Force are fitted with conventional oxygen systems in which a replenishable store of oxygen is carried, most often as liquid oxygen and the flow of gas to each crew member is controlled by an individual pressure demand regulator in which the oxygen is diluted with cabin air to provide breathing gas.Moreover, in-flight refueling capability of present generation fighter aircraft has made it possible to fly for long durations (6 to 8 hours). In such case, the oxygen source becomes one of the limiting factors. In order to meet this requirement, a large supply of Gaseous Oxygen (GASOX) or Liquid Oxygen (LOX) have proven to be a costly affair and the Onboard Oxygen Generating System (OBOGS) has become a very convenient and attractive proposal. The OBOGS employs molecular sieves to adsorb nitrogen from engine bleed air using pressure swing adsorption (PSA) technique, wherein two molecular sieve beds are continuously cycled between steps of pressurization (adsorption) and depressurization (desorption) to generate oxygen enriched breathing gas for aircrew. This paper describes the design of OBOGS using high performance Lithium based Low Silica X-type (Li-LSX) molecular sieves and its performance characteristics. It consists of two Zeolite beds filled with Li-LSX material which adsorbs nitrogen fromengine bleed air tapped from Environmental Control System pipe line. The two beds are cycled by a 5/2 way solenoid valve. The input air is supplied to the solenoid valve through a coalescent filter to reduce moisture from it and a pressure regulator is fitted at the upstream of solenoid valve to regulate the system pressure. The experimental setup for evaluation of OBOGS is also discussed. The OBOGS, presented in this paper, meets all the performance requirements as specified in MIL-C-85521 (AS).

(5,7-Dimethyl-2-oxo-2H-chromen-4-yl)methyl diethyl­dithio­carbamate

In the title compound, C17H21NO2S2, the coumarin ring system is nearly planar, with a maximum deviation of 0.080 (2) Å from the mean plane. An intra­molecular C—H⋯S hydrogen bond occurs. The crystal structure features C—H⋯S hydrogen bonds and weak π–π inter­actions with a centroid–centroid distance of 3.679 (1) Å

(5,7-Dimethyl-2-oxo-2H-chromen-4-yl)methyl pyrrolidine-1-carbodithio­ate

In the title compound, C17H19NO2S2, the 2H-chromene ring system is almost planar, with a maximum deviation of 0.044 (2) Å, and the pyrrolidine ring adopts an envelope conformation. The dihedral angle between the 2H-chromene system and the planar part of the pyrrolidine ring is 83.65 (8)°. A weak intra­molecular C—H⋯S hydrogen bond occurs. The crystal structure features C—H⋯O hydrogen bonds and π–π inter­actions, with a centroid–centroid distance of 3.5728 (16) Å

Optimization of process parameters of cryogenic treatment on Al/Al2O3 MMCs by Taguchi method for tensile strength

Engineering materials are given different types of treatment to impart desired properties to the materials to make them suitable for the intended application. The conventional method is heat treatment. It is being followed by many centuries but the treatment of materials below the room temperature is altogether a new concept to enhance the material properties. When the materials are subjected to deep freezing up to -1960C the change in the morphology results in the stability of microstructure & dimensions. Many researchers have proved the usefulness of cryogenic treatment on ferrous materials. But a very little amount of work has been found in the area of nonferrous materials. Taguchi approach was applied to optimize the process parameters of cryogenic treatment on Al6061-Al2O3 MMCs. The results were experimentally validated. It is found that, the Taguchi approach can be used as an effective tool in optimizing the process variables to minimise the laborious effort in conduction of experiments

(6-Meth­oxy-2-oxo-2H-chromen-4-yl)methyl pyrrolidine-1-carbodithio­ate

In the title compound, C16H17NO3S2, the 2H-chromene ring is close to being planar [maximum deviation = 0.034 (2) Å] and the pyrrolidine ring is twisted about the C—C bond opposite the N atom. The dihedral angle between the ring-system planes is 75.24 (16)° and an intra­molecular C—H⋯S inter­action occurs. In the crystal, mol­ecules are linked by C—H⋯O hydrogen bonds and the packing also exhibits π–π inter­actions, with a distance of 3.6106 (13) Å between the centroids of the benzene rings of neighbouring mol­ecules

Modern Genomic Tools for Pigeonpea Improvement: Status and Prospects

Pigeonpea owing to its ability to sustain harsh environment and limited input/water requirement remains an excellent remunerative crop in the face of increasing climatic adversities. With nearly 70% share in global pigeonpea production, India is the leading pigeonpea producing country. Since the mid-1900s, constant research efforts directed to improve yield and resistance levels of pigeonpea have resulted in the development and deployment of several commercially accepted cultivars in India, accommodating into diverse agro-climatic zones. However, the crop productivity needs incremental improvements in order to meet the growing nutritional demands, especially in developing countries like India where pigeonpea forms a dominant part of vegetarian diet. Empowering crop improvement strategies with genomic tool kit is imperative to attain the project gains in crop yield. In the context, adoption of next-generation sequencing (NGS) technology has helped establish a wide range of genomic resources to support pigeonpea breeding, and the existing molecular tool kit includes genome-wide genetic markers, transcriptome/genome assemblies, and candidate genes/QTLs for target traits. Similarly, availability of whole mitochondrial genome sequence and derived DNA markers is immensely relevant in order to furthering the understanding of cytoplasmic male sterility (CMS) system and hybrid breeding. This chapter covers the progress of developing modern genomic resources in pigeonpea and highlights their vital role in designing future crop breeding schemes

(6-Methoxy-2-oxo-2H-chromen-4-yl)methyl morpholine-4-carbodithioate

In the title compound, C16H17NO4S2, the 2H-chromene ring system is nearly planar, with a maximum deviation of 0.070 (1) Å, and the morpholine ring adopts a chair conformation; the bond-angle sum for its N atom is 357.9°. The dihedral angle between the the 2H-chromene ring and the best plane through the morpholine ring is 89.09 (6)°. An intramolecular C—H...S hydrogen bond occurs. In the crystal, C—H...O hydrogen bonds generate R22(8) rings and π–π interactions occur between fused benzene rings of the chromene system [shortest centroid–centroid distance = 3.5487 (8) Å]

N-(6-Chloro-1-methyl-1H-imidazo4,5-cpyridin-4-yl)benzenesulfonamide

The asymmetric unit of the title compound, C13H 11ClN4O2S, contains two molecules (A and B), in which the dihedral angles between the 1H-imidazo4,5-cpyridine system and terminal phenyl ring are 80.83(10) and 62.34(1)°. In the crystal, A-B dimers are linked by pairs of N-H..N hydrogen bonds, which generate R 2 2(10) loops. The dimers are linked by C-H..O and C-H..Cl interactions, generating a three-dimensional network. Aromatic �-� stacking interactions shortest centroid-centroid distance = 3.5211(12)à are also observed

1,1',1'',1'''-(Oxydi­methane­tri­yl)tetra­kis­(4-fluoro­benzene)

In the title compound, C26H18F4O 2, the dihedral angles between pairs of benzene rings linked to the same C atom are 80.55(8) and 79.11(7)°. The crystal packing features C-H..� interactions and shows stacking when viewed along the c axis