Atom-bond-connectivity index of certain graphs

The ABC index is one of the most applicable topological graph indices and several properties of it has been studied already due to its extensive chemical applications. Several variants of it have also been defined and used for several reasons. In this paper, we calculate the atom-bond connectivity index of some derived graphs such as double graphs, subdivision graphs and complements of some standard graphs.Publisher's Versio

Diversification of sorghum male-sterile lines at ICRISAT

Wor l d sorghum product ion was approximately 54 million t from 44 million ha in 1995.Developing countries account for roughly 9 0% of t h e area and 70% of product ion. In Asia about 15 million t ar e produced annually from about 14.1 million ha (FAO 1996) .Sorghum i s grown in a wide range of environments,and encounters various biotic and abiotic stresses such as drought , low temperatures , Al + 3 toxicity, Striga, stemborer , shootfly, head bug, midge, grain mold, downy mildew, anthracnose, leaf blight , and rust . Breeding for resistance to these stresses stabilizes yield levels and is a relatively inexpensive way t o protect t h e crop from t h e major yield constraints. With the discovery of cytoplasmic-nuclear male-sterility (Stephens and Holland 1954),hybrids became popular with farmers in USA, China, India, Austral ia, and Thai land. In recent years, the r e has been increasing international collaboration on sorghum research. ICRISAT aims t o develop high-yielding and diversified, broad-based genetic materials (gene pools, varieties, and seed parents) wi t h resistance to various stresses, and thus better serve the needs of collaborators and partners. This paper summarizes ICRISAT' s efforts in diversifying and improving male-sterile lines through a trait - based breeding approach

Polymorphism of (Z)-3-Bromopropenoic acid: a high and low Z' pair

Two polymorphic forms of (Z)-3-Bromopropenoic acid are reported. Form I (monoclinic, P21/c) with Z' = 1 is obtained from a range of solvents while Form II (monoclinic, P21/n) with Z' = 4 can be prepared only from either benzene or toluene. Both forms are isolated at room temperature. The molecules in both polymorphs interact with one another through similar dominant hydrogen bonding motifs; however, the packing arrangement differs in the prevalence of weaker hydrogen bonds in the metastable Form II. Analysis of this high and low Z′ polymorphic pair using differential scanning calorimetry, grinding and slurry experiments, coupled with lattice energy calculations suggests that the low Z′ form I is the most stable under ambient conditions. 2D fingerprint plots derived from Hirshfeld surfaces highlight the more extensive hydrogen bonding in Form II while Form I is more densely packed. This polymorphic pair mat be a candidate for the role of solution pre-aggregation in the formation of high Z′ forms

Studies on an Ejector-Absorption Refrigeration Cycle with New Working Fluid Pairs

Abstract The Ejector-Absorption Refrigeration System (EARS) c ombines the advantages of conventional absorption system and ejector refrigeration system. This paper makes a comparative study of EARS operating on new working fluid pairs such as R124-DMAC, R134a-DMAC and R32-DMAC. Results show that R124-DMAC and R134a-DMAC give good performance at low values of generator and evaporator temperatures. R32-DMAC has drawbacks such as high generator pressures and high circulation ratios. Since R124 is a HCFC and has to be phased out in the near future, R134a-DMAC may be the preferred working pair for low heat source temperature applications. Key words: absorption cycle, ejector cycle, new working fluids. Introduction Heat operated cooling systems are attractive when thermal energy is available freely or at low cost, and high-grade electrical energy is expensive. Both absorption and ejector refrigeration systems are heat powered. From the energy and environmental points of view, considerable scope exists for employing new working fluids in these systems. Conventional fluids being used in vapour absorption refrigeration systems (VARS) namely, water-LiBr and NH 3 -water, have certain drawbacks and limitations in terms of physical characteristics and operating temperatures. In order to overcome these, many new working fluid pairs for VARS based on HFCs and HCFCs have been suggested Theoretical analysis The analysis is carried out for steady state operation of the EARS shown schematically i

Polymorphism and Phase Transformation Behavior of Solid Forms of 4-Amino-3,5-dinitrobenzamide

We report the preparation, analysis, and phase transformation behavior of polymorphs and the hydrate of 4-amino-3,5-dinitrobenzamide. The compound crystallizes in four different polymorphic forms, Form I (monoclinic, P2(1)/n), Form II (orthorhombic, Pbca), Form III (monoclinic, P2(1)/c), and Form IV (monoclinic, P2(1)/c). Interestingly, a hydrate (triclinic, P (1) over bar) of the compound is also discovered during the systematic identification of the polymorphs. Analysis of the polymorphs has been investigated using hot stage microscopy, differential scanning calorimetry, in situ variable-temperature powder X-ray diffraction, and single-crystal X-ray diffraction. On heating, all of the solid forms convert into Form I irreversibly, and on further heating, melting is observed. In situ single-crystal X-ray diffraction studies revealed that Form II transforms to Form I above 175 degrees C via single-crystal-to-single-crystal transformation. The hydrate, on heating, undergoes a double phase transition, first to Form III upon losing water in a single-crystal-to-single-crystal fashion and then to a more stable polymorph Form I on further heating. Thermal analysis leads to the conclusion that Form II appears to be the most stable phase at ambient conditions, whereas Form I is more stable at higher temperature

Phenazine and 10H-phenothiazine cocrystal stabilized by N-H···N and C-H···S hydrogen bonds

A 1:1 co-crystal of phenazine and phenothiazine was prepared. The crystal structure was determined by using a single crystal X-ray crystallography technique. Analysis of the crystal revealed that the molecular complex crystallizes in monoclinic P21/n space group, C12H8N2·C12H9NS, a = 9.068(2) Å, b = 8.872(2) Å, c = 23.935(4) Å, β = 92.16(4)°, V = 1924.1(6) Å3, Z = 4, T = 293(2) K, μ(MoKα) = 0.182 mm-1, Dcalc = 1.310 g/cm3, 8057 reflections measured (3.4° ≤ 2Θ ≤ 46.54°), 2751 unique (Rint = 0.0559, Rsigma = 0.0618) which were used in all calculations. The final R1 was 0.0548 (>2sigma(I)) and wR2 was 0.1029 (all data). The molecules recognize each other through N-H···N and C-H···N hydrogen bonds, thus producing a tetramer unit. These units further interact with one another via C-H···S hydrogen bonds

Polymorphism and Phase Transformation Behavior of Solid Forms of 4‑Amino-3,5-dinitrobenzamide

We report the preparation, analysis, and phase transformation behavior of polymorphs and the hydrate of 4-amino-3,5-dinitrobenzamide. The compound crystallizes in four different polymorphic forms, Form I (monoclinic, <i>P</i>2₁/<i>n</i>), Form II (orthorhombic, <i>Pbca</i>), Form III (monoclinic, <i>P</i>2₁/<i>c</i>), and Form IV (monoclinic, <i>P</i>2₁/<i>c</i>). Interestingly, a hydrate (triclinic, <i>P</i>1̅) of the compound is also discovered during the systematic identification of the polymorphs. Analysis of the polymorphs has been investigated using hot stage microscopy, differential scanning calorimetry, in situ variable-temperature powder X-ray diffraction, and single-crystal X-ray diffraction. On heating, all of the solid forms convert into Form I irreversibly, and on further heating, melting is observed. In situ single-crystal X-ray diffraction studies revealed that Form II transforms to Form I above 175 °C via single-crystal-to-single-crystal transformation. The hydrate, on heating, undergoes a double phase transition, first to Form III upon losing water in a single-crystal-to-single-crystal fashion and then to a more stable polymorph Form I on further heating. Thermal analysis leads to the conclusion that Form II appears to be the most stable phase at ambient conditions, whereas Form I is more stable at higher temperature

Metal Complexes of 2,2′-Bipyridine-4,4′-diamine as Metallo-Tectons for Hydrogen Bonded Networks

Transition metal complexes of the ligand 2,2′-bipyridine-4,4′-diamine (bpy4da) form three-dimensional (3D) hydrogen bonding networks with the [M­(bpy4da)₃]²⁺ species, a hydrogen donor metallo-tecton with carboxylate counteranions as hydrogen bond acceptors within the complexes [[Ni­(bpy4da)₃]·(Hbpc)­(bpc)_0.5(dmf)_<i>n</i>, [Ni­(bpy4da)₃].(bpc)­(dmf)_<i>n</i>, and [Ni­(bpy4da)₃]·(Htma)·4­(dmf) where H₂bpc = biphenyl-4,4′-dicarboxylic acid, H₃tma = trimesic acid, and dmf = dimethylformamide. Terephthalate, on the other hand, bridges between Cu­(II) centers in complexes [Cu₂(bpy4da)₄(tpa)]·2­(NO₃)·5­(dmf) and [Cu₂(bpy4da)₄(tpa)]·2­(NO₃)·4.5­(dmf)·(H₂O) (where H₂tpa = terephthalic acid) whose structures both feature different 3D hydrogen bonded networks. The crystal structures of hydrated [Cd­(bpy4da)₃]·2Cl and [Co­(bpy4da)₂(NO₃)]₂·2­(NO₃)·4.5­(dmf) are also reported

Metal Complexes of 2,2′-Bipyridine-4,4′-diamine as Metallo-Tectons for Hydrogen Bonded Networks

Transition metal complexes of the ligand 2,2′-bipyridine-4,4′-diamine (bpy4da) form three-dimensional (3D) hydrogen bonding networks with the [M­(bpy4da)₃]²⁺ species, a hydrogen donor metallo-tecton with carboxylate counteranions as hydrogen bond acceptors within the complexes [[Ni­(bpy4da)₃]·(Hbpc)­(bpc)_0.5(dmf)_<i>n</i>, [Ni­(bpy4da)₃].(bpc)­(dmf)_<i>n</i>, and [Ni­(bpy4da)₃]·(Htma)·4­(dmf) where H₂bpc = biphenyl-4,4′-dicarboxylic acid, H₃tma = trimesic acid, and dmf = dimethylformamide. Terephthalate, on the other hand, bridges between Cu­(II) centers in complexes [Cu₂(bpy4da)₄(tpa)]·2­(NO₃)·5­(dmf) and [Cu₂(bpy4da)₄(tpa)]·2­(NO₃)·4.5­(dmf)·(H₂O) (where H₂tpa = terephthalic acid) whose structures both feature different 3D hydrogen bonded networks. The crystal structures of hydrated [Cd­(bpy4da)₃]·2Cl and [Co­(bpy4da)₂(NO₃)]₂·2­(NO₃)·4.5­(dmf) are also reported