Search

Microstructural and electrochemical corrosion behaviours of Al40(SiCrFeMnNiCu)60(at %) high entropy alloy (HEA) were studied. The as-cast-alloy formed B2 and Cr5Si3intermetallic phases. The HEA showed active, passive and transpassive behaviour for pH (0–3), and spontaneous passivity for pH (14–11). The HEA showed higher transpassive dissolution at low pH values than alkaline pH values. This has been attributed to minor variation in the passive film composition of the HEA between the acidic and alkaline pH condition as observed using X–ray photoelectron spectroscopy (XPS). Considering the beneficial role of copper and silicon in sulphuric acid in stabilizing the passive film in reducing the critical current density for passivation and also the role of silicon in stabilizing the passive film, they are suggested to be responsible for the improved passivity. In 3.5 wt% NaCl solution, the alloy did not show any kind of passivity. The selective dissolution of the alloy was evident at B2/Cr5Si3interface regions and the Cr5Si3phase showed relatively more resistance to corrosion.

In this work, atomic layer etching (ALE) of Si compounds using H2or N2plasma modification followed by fluorine radical exposure is discussed. It is shown that the H2plasma modification process promotes the selective etching of SiN, SiC, and SiCO versus SiO2. The N2plasma modification, on the other hand, enables the selective etching of SiC and SiCO versus SiN and SiO2. The origin of the etching selectivity between different Si compounds is investigated using a combination of in situSE and FTIR supported by several exsituanalysis techniques. It is shown that the formation of a hydrogen-rich layer after plasma modification is essential to enable the ALE process. The hydrogen-rich layer can be formed due to ion and radicals of the modification plasma (H2plasma modification) or be a result of the reconfiguration of hydrogen that is already present in the film (N2plasma modification). The obtained insights are expected to further enhance the etching selectivity of Si compound ALE processes. Furthermore, it is anticipated that the process can be extended to many other compound materials such as Ti and Hf, as well as enable selective etching between their oxides, carbides, and nitrides.

Multinary earth-abundant chalcogenides, like kesterite, Cu2ZnSnS4(CZTS), have attracted attention in sustainable energy applications like photovoltaics and thermoelectrics. High-energy ball milling provides a facile way for the synthesis of pure cubic CZTS. This sulfide crystallizes in a sphalerite-type structure with complete occupational disorder in the cationic substructure and a considerable amount of stacking faults. Heating of the material leads to the slow and irreversible transition into disordered, tetragonal kesterite, which is associated with a significant decrease in thermoelectric properties. Hence, a deep understanding of the phase transition process and its kinetics is a prerequisite for further crystal engineering. In situX-ray powder diffraction and Raman spectroscopy supported by density functional theory calculations and ab initiomolecular dynamics simulations (AIMD) were employed to gain microstructural insights into the phase transition process. Heating leads to a growth of the crystalline domains, which is associated with a reduction of strain. The domain growth reduces the stabilization of the metastable cubic phase by nanostructuring. This eventually leads to the segregation of tin cations, which corresponds to the beginning of the transition into the tetragonal phase. AIMD simulations indicate that the presence of faulting planes promotes the tin diffusion. As stacking faults appear to be energetically less favorable in the tetragonal disordered form, the stacking fault disorder is reduced upon heating, leading to an additional strain reduction.

Nanoporous anatase with a thin interconnected filmlike morphology has been synthesized in a single step by coupling a nonhydrolytic condensation reaction of a Ti precursor with a hybrid sol−gel combustion reaction. The method combines the advantages of a conventional sol−gel method for the formation of porous structures with the high crystallinity of the products obtained by combustion methods to yield highly crystalline, phase-pure nanoporous anatase. The generation of pores is initiated by the formation of reverse micelles in a polymeric polycondensation product, which expand during heating, leading to larger pores. A reaction scheme involving a complex formation and nonhydrolytic polycondensation reaction with ester elimination leads to the formation of an extended Ti−O−Ti network. The effect of process parameters, such as temperature and relative ratio of cosurfactants, on phase formation has been studied. The possibility of band gap engineering by controlled doping during synthesis and the possibility of attachment of molecular/nanoparticle sensitizers provide opportunities for easy preparation of photoanodes for solar cell applications.

Heterosis and its relation to genetic divergence between the parents was explored in a diallel cross among 8 inbred lines of maize (Zea maysL.) selected from an array of 32 inbreds, derived from 4 genetically and geographically diverse populations, on the basis of genetic distance deduced through Mahalanobis’ D2statistic on 20 diagnostic and agronomic traits. Pooled analysis was carried out for calculating heterosis as the error mean squares at the two locations were homogenous. Heterobelteosis was observed in all the traits under study for many crosses. Among the top ten heterotic hybrids, the highest frequency of crosses were with intermediate genetic distance followed by high genetic divergence between the parents. However, a few crosses with low genetic divergence also fell in the category of top 10 hybrids. It was realized that parents with high per seperformance and intermediate genetic divergence produced highly heterotic as well as high yielding hybrid.

The kinetics of decomposition of limestone was studied using both non-isothermal and isothermal methods. The mechanism and kinetics of thermal decomposition were studied using Arrhenius equation applied to solid state reactions. It was found that in both non-isothermal and isothermal methods limestone seemed to be decomposed via a zero order reaction mechanism. The energy of activation for the non-isothermal and isothermal decompositions of limestone was 157.79 and 181.43 kJ.mol−1respectively. Similarly, In Avalues for non-isothermal and isothermal decomposition were found to be 14.2 and 13.2(s−1) respectively.

Abstract: Mullite was developed by reaction sintering of sillimanite beach sand and calcined alumina. Two varieties of sillimanite beach sand viz. S and Z having different compositions were selected. Synthesis and properties of mullite were very much dependent on the sillimanite beach sand composition. Presence of higher amount of impurities in the Z-variety of sillimanite sand favours the densification by liquid phase formation. Presence of zircon in Z-variety increases the hardness and fracture toughness. Alumina addition improves the mechanical/thermomechanical properties of the samples. Mullite retains the usual orthorhombic habit of sillimanite. Rounded to sub rounded zirconia dispersed within the mullite matrix of the sample ZA is noticed.

Laser Doppler interferometry has been used to determine the strain and piezoelectric response of Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PMN-PT) electrostrictive ceramics as a function of electric fields up to 4 MV m^-1, frequencies between 0.1 Hz and 2.5 kHz and DC bias fields up to 3 MV m^-1. The strain and polarization of PMN-15 with a composition of 0.9PMN-0.1PT and PMN-38 with a composition of 0.85PMN-0.15PT both produced by TRS ceramics, have been measured at room temperature. The strain and polarization responses of PMN-15 ceramics under an electric field up to 4 MV m^-1 have been fitted to a polynomial model. The results suggest that a quadratic dependence of strain on polarization is not valid for large electric fields and that higher-order terms must be included. Our measurements showed that the effective piezoelectric coefficient, d₃₃, of PMN-15 ceramics had a maximum value of 800 pm V^-1 at a bias field of 0.67 MV m^-1 and had little frequency dependence in the frequency range from 1 Hz up to 2.5 kHz. PMN-38 ceramic showed a maximum d₃₃ of 1200 pm V^-1 at a bias field of 0.43 MV m^-1 and the d₃₃ of this material showed a clear frequency dependence from 1 Hz up to 2.5 kHz.

Various piezoelectric, elastic and dielectric constants of typical soft and hard lead zirconate titanate (PZT) ceramics have been determined as a function of applied AC field, DC bias field, pre-stress, temperature and frequency. Our results show significant non-linear effects and many of the effects are caused by extrinsic, or domain related effects. These effects include stress or field induced clamping and unclamping (de-ageing) of domain walls. The time dependence of the piezoelectric response has also been studied and our results provide evidence of thermally activated domain switching in piezoelectric ceramics. The use of Arrhenius type plots has led to the determination of average activation energies in typical PZT ceramics. We have found the activation energy to range between 0.29 and 0.32 eV in Navy Type I PZT ceramics and between 0.62 and 0.80 eV in Navy Type III ceramics.

Abstract: The high spin states in N=80 139Pr have been investigated by in-beam γ-spectroscopic techniques following the reaction 130Te (14N, 5n) reaction at E=75 MeV, using a gamma detector array, consisting of seven 23% compton-suppressed high purity germanium detectors and a multiplicity ball of fourteen bismuth germanate elements. Based on γ-γ coincidence data, the level scheme of 139Pr has been considerably extended up to 7.2 MeV excitation. Tentative spin-parity assignments are done for the newly proposed levels on the basis of the DCO ratios corresponding to strong gates and the available information from the earlier light ion experiments.

Abstract: The nucleus 3065 Zn was studied using the 52Cr(16O, 2pn)65Zn reaction at a beam energy of 65 MeV. The level scheme is extended up to an excitation energy of 10.57 MeV for spin-parity (41/2ħ) with several newly observed transitions placed in it.

Micellar properties of the binary and ternary surfactant combinations of sodium dodecyl benzene sulfonate, polyoxyethylene sorbitan monolaurate, and polyoxyethylene lauryl ether have been investigated in detail by employing tensiometric, fluorometric, and conductometric techniques in aqueous medium. The critical micelle concentrations, counterion binding, interfacial adsorption, energetics of micellization as well as adsorption, micropolarity, aggregation number, composition of the micellar species, and molecular interaction parameters in the mixed micelles have been evaluated. The physicochemical properties of the systems are observed to depend on the solution composition. We have estimated the characteristics of the micellar aggregates such as composition, activity coefficients, critical micelle concentration, and synergism of the binary and ternary surfactant systems following the treatments of Clint, Rubingh, Motomura, et al. and Rubingh and Holland.

Excited states of 63Cu were populated via the 52Cr+10O (65 MeV) reaction using the gamma detector array equipped with charged particle detector array for reaction channel separation. On the basis of γ-γ coincidence relations and angular distribution ratios, a level scheme was constructed up to En=7 MeV and Jπ=23/2(+). The decay scheme deduced was interpreted in terms of shell model calculations, with a restricted basis of the f5/2, p3/2, p1/2, g9/2orbitals outside a 5628Ni core.

Osteopontin (OPN) is a sialic acid-rich, adhesive, extracellular matrix (ECM) protein with Arg-Gly-Asp cell-binding sequence that interacts with several integrins, including alpha(v)beta(3). Since the ECM is a key regulator of mammary gland morphogenesis, and mammary epithelial cells express OPN at elevated levels, we sought to determine whether this protein plays a role in the postnatal mammary gland development. By generating transgenic mice that express OPN antisense-RNA (AS-OPN mice) in the mammary epithelia we achieved suppression of OPN production in this organ. The pregnant AS-OPN mice displayed a lack of mammary alveolar structures, a drastic reduction in the synthesis of beta-casein, whey acidic milk protein, and lactation deficiency. In agreement with these findings, we uncovered that a mammary cell line, NMuMG, which undergoes both structural and functional differentiation on ECM-coated plates, when transfected with an antisense OPN-cDNA construct, failed to undergo such differentiation. Furthermore, the results of gel-invasion assays demonstrated that these cells manifest elevated matrix metalloproteinase (MMP) activity when OPN expression is significantly reduced. The identity of this proteinase as MMP-2 is confirmed by Western blotting, zymography, and inhibition of its activity by a specific inhibitor, TIMP-2. Taken together, our results demonstrate, for the first time, an essential role of OPN in mammary gland differentiation and that the molecular mechanism(s) of its action, at least in part, involves down-regulation of MMP-2.

We have measured the electromechanical properties of the “reversible” electrostrictive ceramic (TRS Ceramics Inc) PMN/PT/La (0.9/0.1/1%) at room temperature, which is slightly above Tmax, the temperature at which the real part of the material's low frequency permittivity has a maximum. Under DC bias fields up to about 0.5 MV/m, the material behaves as a piezoelectric ceramic material with C\infty symmetry. The effective piezoelectric and electromechanical coupling coefficients having a linear dependence on the bias field while the dielectric constant (at constant stress) and elastic constant (at constant field) are found to have a quadratic dependence on the bias field. Under higher bias fields, the piezoelectric and electromechanical coupling coefficients begin to saturate. In order to understand our measurements, we have used Mason's model for electrostriction and we have developed a nonlinear macroscopic model for electromechanical materials based on a Taylor's series expansion of the thermodynamic potentials to third and higher order terms in field and stress. The resonance equations for the DC biased length extensional resonator have been obtained and DC biased resonance techniques are shown to be useful in determining the electrostrictive and other higher order coefficients. The saturation at higher bias fields arises from higher fourth order terms (S∞kE4, with k negative) that result from saturation in the dielectric response.

Presents an overview of the controversy over the publication of `The Satanic Verses,' by Salman Rushdie and the FATWA (death sentence) laid on the author by Ayatollah Khomeini. Portrait of Rushdie; Impact of the book and resulting furor on his life; How the conflict reflects England's struggle to come to terms with its non-European immigrants; Rushdie's plea for compromise from the Muslim community. INSET: A chronology.;Publish and perish, by C.B. & B.M..

Recent advances in fiber optic technology (viz. its promise to provide information-carrying capacity in the Gpbs range over long repeater-free distances) has triggered tremendous activity in the study of unidirectional bus networks (because signal flow in the fiber is unidirectional). A popular network structure that has received significant attention is the Dual-bus Unidirectional Broadcast System (DUBS) network topology. Most of the access mechanism studied on this structure are based on round-robin scheduling (or some variation thereof). However since round-robin schemes suffer a loss of channel capacity because of their inter-round overhead (which can be significant for long high-speed buses), a probabilistic scheduling strategy, called pi-persistent protocol, has recently been proposed and studied for single channel unidirectional bus systems. Our concern here is to apply this probabilistic scheduling strategy to each bus in DUBS, and study the corresponding network performance. In so doing, we allow stations to buffer multiple packets, represent a station's queue size by a Markov chain model, and employ an independence assumption. We find that the average packet delay is bounded and the maximum network throughput approaches two pkt/slot with increasing buffer size. Further, the protocol's performance is insensitive to bus characteristics, and it appears to be a particularly well suited for fiber-optic network application requiring long distances and high bandwidth. Simulation results, which verify the analytical model, are also included.

Genetic markers consisting of 11 blood group and red cell enzyme systems were investigated in 14 endogamous groups of north-west India. Genetic differentiation among the samples as indicated by FST is appreciable, reflecting the ethnic diversity characteristic of this region. Local variation within each state is lower, indicating a geographical component to the total variation. This variation is refined by calculations of genetic distances, which show that the tribals and low-caste groups are closer together but well separated from high-caste Brahmins and other non-tribal middle castes. There is a slight possibility of disruptive selection, but the analyses suggest that the differences in genetic structure in north-west India are more likely to be due to their breeding structure, differential migration and ethnic affiliation.

The effect of parity on placental weight and birth weight is examined through a series of birth records from an Indian population in Calcutta. Placental weight and birth weight increase with parity, the maximum increment occurring between parities 1 and 2. This is compatible with a hypothesis of sensitization of the mother to foetal, paternally derived, antigens.The three common placental alkaline phosphatase enzymic genotypes have no effect on determining foetal development.

Blood specimens from 134 Oraon, a Dravidian-speaking tribe in Bihar, India, have been tested for haptoglobin, transferrin, ceruloplasmin, phosphoglucomutase, lactate dehydrogenase, albumin, and malate dehydrogenase types by starch gel electrophoresis. Low Hp1 and high TfD gene frequencies emerge.

We previously reported the purification and characterization of the polyhedrin promoter-binding protein (PPBP), an unusual DNA-binding protein that interacts with transcriptionally important motifs of the baculovirus polyhedrin gene promoter (S. Burma, B. Mukherjee, A. Jain, S. Habib, and S.E. Hasnain, J. Biol. Chem. (1994) 269, 2750-2757. PPBP also exhibits a sequence-specific single-stranded DNA-binding activity. Gel retardations and competition analyses with double- and single-stranded oligonucleotides indicated that PPBP binds the coding strand and not the noncoding strand of the promoter. This was further confirmed by UV cross-linking and Southwestern blotting experiments. Gel retardations with mutated oligonucleotides indicated that both dsDNA and ssDNA binding involve common AATA-AATAAGTATT motifs. However, ssDNA binding is dependent upon ionic interactions unlike dsDNA binding, which is mainly through nonionic interactions. The affinity of PPBP for the coding strand appears to be higher than that for duplex promoter DNA. Interestingly, the PPBP-coding strand complex has a longer half-life (approximately 60 min) than the PPBP-duplex promoter complex (approximately 15 min). PPBP represents a unique example of an "initiator" promoter-binding protein with dual dsDNA and ssDNA binding activities, and this reconciles very well with the unusual binding characteristics displayed by it. The formation of the PPBP-coding strand complex in vivo may be a crucial step for the exceptionally high and repeated rounds of transcriptional activity of the baculovirus polyhedrin gene promoter.

SummaryA survey was conducted to study the genetic differentiation among 16 tribal groups of Orissa, Madhya Pradesh, and Maharashtra belonging to different ethnic and linguistic affiliations. Sixteen hundred and fifteen blood samples from both sexes were tested for 5 red cell enzyme systems: ACP, ESD, PGD, GLO, LDH, and Hb pattern. Three hundred and nineteen male individuals were tested for G-6-PD enzyme deficiency. The distribution of the enzyme markers and Hb show a range of variation which are more or less within the Indian range. Case of homozygous HbSS were detected in all the tribes except 3 tribes in Orissa. Two cases of LDH Cal-1 homozygote were found in two Dravidian language speaking Orissa tribes. The χ2-values for testing the homogeneity of gene frequencies indicate a non-significant heterogeneity for all alleles in the individual system. Within population diversity seems to be larger than between population diversity. The degree of over all genetic differentiation as measured by GSTvalue is 0.0154±0.0071.

SummaryThree populations (Poliya, Deshi, and Tiyor) of the Koch ethnic group have been studied for the distribution of three serum protein and four red cell enzyme polymorphisms. There was no significant difference in the allelic frequencies of these systems in the three populations of the Koch ethnic group. The overall gene frequencies were as follows: Hp1, 0.21; Gc1F, 0.34; Gc1s, 0.36; Gc2, 0.30; TfC1, 0.66; TfC2, 0.26; TfC3, 0.001; TfD, 0.06; GLO1, 0.21; PGI2, 0.04; AK2, 0.01; PGM1+, 0.80; PGM1−, 0.06; PGM2+, 0.11 and PGM2−, 0.02. The phenotypic distribution at all the loci was at Hardy-Weinberg equilibrium.

Chronic dieldrin administration to rats (5 mg/kg/day) produced pathological changes in liver and kidney tissues. Dieldrin treated rats showed high levels of liver ascorbic acid and increased activities of inorganic pyrophosphatase in brain and glucose-6-phosphatase in liver. The activities of Mg2+-ATPase in liver and acetylcholinesterase in brain were decreased under toxic doses of dieldrin. L-Ascorbic acid supplements in treated animals could partially prevent the pathological alterations, as observed histologically in liver and kidney tissues. Administration of this vitamin could also prevent alterations in some enzyme activities produced by toxic dieldrin doses.

Lipopolysaccharides ofSalmonella typhimuriuminhibit the activity of acetylcholinesterasein vitroin both synaptosomal and erythrocyte membranes. Arrhenius plots show that the transition temperatures of membrane bound acetylcholinesterase are significantly reduced in the presence of lipopolysaccharides, and the activation energies above and below transition temperature have increased with the lowering of transition temperature. These results indicate that an alteration in the fluidity of the phospholipid layer of the membranes, may be responsible for the membrane-specific effect of lipopoly-saccharides on acetylcholinesterase activity.

The standard IEEE procedure for determining the piezoelectric, dielectric, and elastic constants associated with the radial mode resonance of piezoelectric materials treats these constants as real rather than complex quantities. This approach is valid in the case of piezoelectric materials with low losses such as Lead Zirconate Titanate. However new lossy materials, such as ceramic-polymer composites, are becoming important to transducer designers. For such materials the losses can be taken into account by treating the constants as complex quantities. This paper presents a method to determine the complex form of the above constants. These constants are calculated from the experimental values of the first and second series resonance frequencies, the first parallel resonance frequency and appropriate half band frequencies and the low frequency admittance of the material, all of which can be measured on one disk sample. The method has also been used to automate the IEEE procedure for determining the real parts of the material constants.

Glycoprotein biosynthesis was studied with mouse L-cells grown in suspension culture. Glucose-deprived cells incorporated [3H]mannose into ‘high-mannose’ protein-bound oligosaccharides and a few relatively high-molecular-weight lipid-linked oligosaccharides. The latter were retained by DEAE-cellulose and turned over quite slowly during pulse--chase experiments. Increased heterogeneity in size of lipid-linked oligosaccharides developed during prolonged glucose deprivation. Sequential elongation of lipid-linked oligosaccharides was also observed, and conditions that prevented the assembly of the higher lipid-linked oligosaccharides also prevented the formation of the larger protein-bound ‘high-mannose’ oligosaccharides. In parallel experiments, [3H]mannose was incorporated into a total polyribosome fraction, suggesting that mannose residues were transferred co-translationally to nascent protein. Membrane preparations from these cells catalysed the assembly from UDP-N-acetyl-D-[6-3H]glucosamine and GDP-D-[U-14C]mannose of polyisoprenyl diphosphate derivatives whose oligosaccharide moieties were heterogeneous in size. Elongation of the N-acetyl-D-[6-3H]glucosamine-initiated glycolipids with mannose residues produced several higher lipid-linked oligosaccharides similar to those seen during glucose deprivation in vivo. Glucosylation of these mannose-containing oligosaccharides from UDP-D-[6-3H]glucose was restricted to those of a relatively high molecular weight. Protein-bound saccharides formed in vitro were mainly smaller in size than those assembled on the lipid acceptors. These results support the involvement of lipid-linked saccharides in the synthesis of asparagine-linked glycoproteins, but show both in vivo and in vitro that protein-bound ‘high-mannose’ oligosaccharide formation can occur independently of higher lipid-linked oligosaccharide synthesis.

We have measured the in-phase component of the low-frequency ac impedance of the dc current-induced intermediate state in indium-lead alloy wires. The specimens were mounted in a specific configuration that allowed a proper calculation of their dynamic resistances following the theory developed by Gauthier and Rochon, which is based on London's theory of the intermediate state. The theoretical values are considerably larger than our measurements, particularly near the critical current. We have modified the Gauthier-Rochon theory, to a first approximation, to take account of the Baird-Mukherjee model of the intermediate state and we find reasonably good agreement between the modified theoretical values and our observations.

We have measured the in-phase component of the low-frequency ac impedance of the dc current-induced intermediate state in wires of pure and impure type I superconductors. We find that this dynamic resistance of the intermediate state is greater than the normal state resistance of the wire. The linear response theory for the dynamic resistance developed by Gauthier and Rochon provides a reasonable qualitative understanding of our experimental results.

Experimental studies of the kinetics of flux jumps in type II superconducting disks have shown that flux penetration into the specimen can be described by an exponential function of time. We present a phenomenological theory which uses the concepts of flux pinning and flux flow viscosity to derive a function of the same form as that found experimentally. The function can be used to evaluate the average pinning force and the viscosity from experimental data on flux jumps.

Abstract: The baculovirus expression system employingAutagrapha californica nuclear polyhidrosis virus andSpodoptera frugiperda insect cells in culture has proved very popular for high level expression of heterologous genes: In this system, transcription of the foreign gene is usually driven by the hyperactive and temporally regulated polyhedrin gene promoter. Replacement of the polyhedrin gene, which encodes a 29-kDa occlusion protein (non-essential for viral replication), with a gene of interest leads to an occlusion negative phenotype which serves as a visual marker to select for recombinant viruses. Simultaneous expression of multiple genes can also be achieved. The heterologous proteins synthesized in this system are antigenically, immunologically and functionally identical in most respects to their native counterparts. This mini-review will aim at summarizing the potentials and utility of the baculovirus expression vector system and will address some important questions relating to the biology of this system.

We present a technique to measure the piezoelectric strain (charge) coefficient using an optical lever technique. The optical lever consists of a laser source, a levered mirror connected to the sample and a linear CCD array detector (pixel size = 13 μm). A field on the sample creates a displacement due to the piezoelectric effect. The displacement levers the mirror and diverts the laser beam through an angle which is twice the angular displacement of the levered mirror. The peak intensity of the laser beam on the CCD array is monitored as the field on the sample is ramped. The functional relationship between the piezoelectric coefficient and the displacement, as measured by the CCD array, is linear. Therefore, the technique is inherently ideal for studying non-linear effects. The resolution of the optical lever is less than one nanometer. The system can also be used to make highly localized measurements of the absolute displacements of piezoelectric or electrostrictive materials.

We describe a new method for determining the real and imaginary parts of the material constants of piezoelectric resonators. Our method is applicable to any of the common resonator geometries, it is non-iterative and its accuracy is comparable to that of other methods which are currently in use.

The distribution of placental alkaline phosphatase and lactate dehydrogenase types in 635 placentas from various endogamous groups of Maharashtra have been studied by starch gel electrophoresis. In the case of alkaline phosphatase, 6 common phenotypes and 6 rare phenotypes (F2I1, S1S2, S2S3, I1S2, F1S2, F1I2) are encountered. The highest frequency of Pls1 allele (0·7394) and lowest frequency of Pli1 allele (0·0246) have been found in the Nava-Budha. 6 cases of Cal-1 and 5 cases of Cal-2 types of LDH variants have been observed in the total samples, and Muslims possess the highest frequency of Cal-1 types (3·64%). Population groups are compared with respect to Pl alleles.

Phenotype and gene frequencies for four blood group systems (ABO, MN, Rh and P) and haptoglobin among five endogamous groups of Delhi, India, are reported.All the systems are polymorphic in all the population groups. The average heterozygosity per locus is high (in the range 48–52 per cent) for all the groups.The extent of genic variability among the groups in terms of net codon differences per locus has been studied; the heterogeneity within the groups is large as compared to the between-group heterogeneity.There is no definite clustering of the groups with respect to their biological rank.

The four endogamous groups of fishermen living around the city of Puri, located on the eastern coast of India, were studied for blood groups, red cell enzymes and serum proteins (11 loci). Only 1.3% of the total diversity among the groups studied is due to differences between them (G ST = 0.013). The genetic distances between populations were estimated using Edwards and Cavalli-Sforza's method. The pattern of genetic distance reflects the geographical distribution of these groups. In general, these observations support the patterns of variation based on anthropometric and dermatoglyphic variables.

Blood samples from 898 individuals of nine endogamous groups of West Bengal, India were typed for determining the haplotypic structure in the -light chain (Gm) and x-light chain (Km) of immunoglobulin (IgG). The Gm haplotype frequencies detected by Glm (1), Glm (2) and G3m (5) markers suggest that in this eastern state of India there is considerable variation of frequencies of the typical Mongoloid haplotype Gm1,5, which shows a high incidence in Rajbanshi, Rabha, Garo and Lodha groups. On the contrary, this haplotype is probably absent in the high caste groups, Rarhi Brahmin and Vaidya, and is relatively infrequent in Jalia Kaibarta, a scheduled caste of the south-western part of the state. The Km1 allele is also high in frequency among Rajbanshi, Rabha, Garo and Munda in comparison with Rarhi Brahmin and Vaidya, suggesting the former four groups' strong Mongoloid affiliation.This survey signifies that there is considerable variation in the extent of Mongoloid admixture in Bengali populations. Such admixture is not restricted in specific social class either. It further demonstrates that heterogeneity of the genetic structure of Bengali populations do not correspond to the present social ranking on the basis of caste hierarchy.