Search

The adverse effects of abiotic components of the environment have led to noteworthy increases in drip global agricultural productivity. Among abiotic stresses, heavy metal (HM) stress is an important environmental factor with a significant negative impact on plants and requires serious attention due to its global presence. HMs are mostly found as key chemical components integrated into rock, particularly in industrial and urban areas. Rapid industrial development coupled with urbanization has amplified the accumulation of anthropogenic HMs in the environment. In comparison with organic substances, HMs cannot be decayed by biological interventions and thus remain in the environment for an extended period and subsequently pass through the food chain and subsequently accumulate in the bodies of humans and animals. This review provides a detailed account of the occurrence and behaviour of HMs in the environment, especially in the pedosphere, which affects the soil processes and physiology and biochemistry of plants. However, plants, particularly HM accumulators, are equipped with complex multilevel defense mechanisms to survive HM-induced stress. Here, we attempted to provide an explicit overview of these mechanisms at the cellular and molecular levels. Special emphasis has been given to the potential applications of these HM-tolerant traits in the transgenic development and phytoremediation of HMs, which might shape the future of research in the domains of plant science and agriculture.

The present study describes the potential of gamma rays in enhancing zinc tolerance of Aspergillus niger. Gamma exposed group of A. nigershowed 1.82 times more zinc tolerance than the unirradiated ones. Gamma exposed A. nigergrown in different zinc enriched media, showed increase in growth (expressed in terms of colony forming unit), higher efficiency in zinc uptake and removal, when compared to that of their unirradiated counterparts. The present investigation throws light towards utilizing gamma radiation for formulating more metal-tolerant fungi for bioremediation.

This study explored magnetohydrodynamic (MHD) radiative unsteady free convective hybrid nanofluid flow over an exponentially accelerated vertical plate under the impact of transverse magnetic force with first‐order chemical reaction. The term “hybrid” or “composite” nanofluid refers to a mixture of water‐containing nanoparticles (NPs) of Ag$\rm Ag$and TiO2$\rm TiO_2$that have been dissolved in the base fluid to create the hybrid nanofluid. The crux of the investigation is the attention to two different cases of magnetic force, one being stationary relative to the plate and the other close to the fluid. The Dimensional equations are transformed into dimensionless forms using non‐dimensional quantities. The Laplace Transform technique is used to obtain the closed‐form solutions. Based on those outcomes, the velocity, the temperature, and the concentration distributions of the hybrid nanofluid are evaluated for several sets of values of the physical parameters related to MHD, NP's volume fraction, radiation, porosity, and plate accelerating parameters have been studied through graphs. Furthermore, it is discovered that when the magnetic force is applied to the fluid (L=0)$(L=0)$, the velocity drops with increasing magnetic parameters; nevertheless, the opposite trends occur when the magnetic force is applied to the plate (L=1)$(L=1)$.

Heavy metal pollution is an alarming problem for the ecosystem. Zinc (Zn) is one of the most common heavy metal contaminant in the environment. In recent years different, abatement strategies are being implemented to control metal pollutants, amongst these, bioremediation has gained substantial focus. This paper detailed the Zn uptake and removal efficacies of a Zn tolerant fungal strain, Aspergillus terreus(minimum inhibitory concentration against Zn being 9100 ppm) which was capable of removing 75–35 % Zn from different Zn enriched media. However, the uptake and removal efficacies were found to be decreased with increasing Zn concentrations. FTIR spectra showed involvement of functional groups (present on outer surface of fungal cell wall) in Zn adsorption. Concurrently, Zn decreased the activities of two important metabolic enzymes, CMCase and α-amylase. Scanning electron micrographs clearly demonstrated the structural deformation of fungal hyphae due to Zn exposure. To combat the Zn stress A. terreusupregulated its antioxidative defense system, which is reflected through the significant upregulation of superoxide dismutase and catalase enzyme activities and metal responsive protein (metallothionein) with respect to control.

The fundamental equations of the two dimensional generalized thermoelasticity (L-S model) with one relaxation time parameter in orthotropic elastic slab has been considered under effect of rotation. The normal mode analysis is used to the basic equations of motion and heat conduction equation. Finally, the resulting equations are written in the form of a vector-matrix differential equation which is then solved by the eigenvalue approach. The field variables in the space time domain are obtained numerically. The results corresponding to the cases of conventional thermoelasticity CTE), extended thermoelasticity (ETE) and temperature rate dependent thermoelasticity (TRDTE) are compared by means of graphs.

Controlled fasts can play a valuable role in the diagnosis and management of hypoglycaemia in paediatric clinical practice, but are no substitute for the collecting of appropriate critical samples at the time of hypoglycaemia for metabolic and endocrine studies. Fatty acid oxidation defects, hyperinsulinism and adrenal insufficiency should always be excluded prior to organising controlled fasts. Controlled fasts are safe if conducted in an experienced setting with strict protocols in place. Failure to adhere to protocol can defeat the purpose of the study and can potentially be dangerous. Proper planning in conjunction with the laboratory and close supervision by staff experienced in controlled fasts is crucial to ensure the best quality information is yielded from these procedures.

Complete and incomplete fusion cross-sections for the 9Be+124Snsystem have been measured around the Coulomb barrier energies (ElabC.B=28 MeV) using the on-line gamma ray detection technique. The complete fusion cross-sections of this system have been compared with the two stable projectiles on the same 124Sn target to provide information on the projectile dependence. The brief comparison of the present 9Be+124Sn data with a comprehensive and recent study of the neighbouring system 9Be+144Sm is also given.

Diastereoselective reductive coupling reactions of ω-vinyl tethered cyclic imides are achieved by a preexisting stereocenter at an allylic position. Particularly noteworthy is the effective use of a 1:2 mixture of Ti(O-i-Pr)4 and n-BuLi to afford the N-acylhemiaminal products in good yields.

The folded tandem ion accelerator (FOTIA) facility set up at BARC has become operational. At present, it is used for elemental analysis studies using the Rutherford backscattering technique. The beams of1H, 7Li, 12C, 16O and 19F have been accelerated up to terminal voltages of about 3 MV and are available for experiments. The terminal voltage is stable within ±2 kV. In this paper, present status of the FOTIA and future plans are discussed.

The beam optics of the 6 MV folded tandem ion accelerator, that has recently been commissioned at Bhabha Atomic Research Centre, Mumbai, is presented. Typical beam trajectories for proton and 12C beams under different conditions, are shown. The constraints on the design due to the use of the infrastructure of the Van de Graaff accelerator, which existed earlier, are discussed.

ABSTRACTT-cell-mediated immune effector mechanisms play an important role in the containment of human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) replication after infection. Both vaccination- and infection-induced T-cell responses are dependent on the host major histocompatibility complex classes I and II (MHC-I and MHC-II) antigens. Here we report that both inherent, host-dependent immune responses to SIVmac251infection and vaccination-induced immune responses to viral antigens were able to reduce virus replication and/or CD4+T-cell loss. Both the presence of the MHC-I Mamu-A*01 genotype and vaccination of rhesus macaques with ALVAC-SIV-gag-pol-env(ALVAC-SIV-gpe) contributed to the restriction of SIVmac251replication during primary infection, preservation of CD4+T cells, and delayed disease progression following intrarectal challenge exposure of the animals to SIVmac251 (561). ALVAC-SIV-gpeimmunization induced cytotoxic T-lymphocyte (CTL) responses cumulatively in 67% of the immunized animals. Following viral challenge, a significant secondary virus-specific CD8+T-cell response was observed in the vaccinated macaques. In the same immunized macaques, a decrease in virus load during primary infection (P= 0.0078) and protection from CD4 loss during both acute and chronic phases of infection (P= 0.0099 and P= 0.03, respectively) were observed. A trend for enhanced survival of the vaccinated macaques was also observed. Neither boosting the ALVAC-SIV-gpewith gp120 immunizations nor administering the vaccine by the combination of mucosal and systemic immunization routes increased significantly the protective effect of the ALVAC-SIV-gpevaccine. While assessing the role of MHC-I Mamu-A*01 alone in the restriction of viremia following challenge of nonvaccinated animals with other SIV isolates, we observed that the virus load was not significantly lower in Mamu-A*01-positive macaques following intravenous challenge with either SIVmac251 (561)or SIVSME660. However, a significant delay in CD4+T-cell loss was observed in Mamu-A*01-positive macaques in each group. Of interest, in the case of intravenous or intrarectal challenge with the chimeric SIV/HIV strains SHIV89.6Por SHIVKU2, respectively, MHC-I Mamu-A*01-positive macaques did not significantly restrict primary viremia. The finding of the protective effect of the Mamu-A*01 molecule parallels the protective effect of the B*5701 HLA allele in HIV-1-infected humans and needs to be accounted for in the evaluation of vaccine efficacy against SIV challenge models.

A water-in-oil microemulsion method has been applied for the preparation of silica-coated iron oxide nanoparticles. Three different nonionic surfactants (Triton X-100, Igepal CO-520, and Brij-97) have been used for the preparation of microemulsions, and their effects on the particle size, crystallinity, and the magnetic properties have been studied. The iron oxide nanoparticles are formed by the coprecipitation reaction of ferrous and ferric salts with inorganic bases. A strong base, NaOH, and a comparatively mild base, NH4OH, have been used in each surfactant to observe whether the basicity has some influence on the crystallization process during particle formation. Transmission electron microscopy, X-ray electron diffraction, and superconducting quantum interference device magnetometry have been employed to study both uncoated and silica-coated iron oxide nanoparticles. All these particles show magnetic behavior close to that of superparamagnetic materials. By use of this method, magnetic nanoparticles as small as 1−2 nm and of very uniform size (percentage standard deviation is less than 10%) have been synthesized. A uniform silica coating as thin as 1 nm encapsulating the bare nanoparticles is formed by the base-catalyzed hydrolysis and the polymerization reaction of tetraethyl orthosilicate in microemulsion. All experimental results are also compared with those for particles synthesized in pure water.

Absorption, fluorescence and fluorescence excitation spectra of 2-(2′-N,N-dimethylaminophenyl)-N-methylbenzimidazole (TMAPBI), 2-(2′-N,N-dimethylamino phenyl)benzimidazole (2-DMAPBI) and 2-(2′-N-methylaminophenyl)-N-methyl benzimidazole (2-N(Me)(NMe)DMAPBI), have been studied in different solvents. Absorption spectra and the semi-empirical quantum mechanical calculations establish the presence of two rotamers in each molecule. Besides the short wavelength (SW) fluorescence band, a long wavelength (LW) emission is observed as a tail to the SW emission band in each molecule. Band maxima of both the emissions are red shifted and the fluorescence quantum yield increased with the increase in the polarity and hydrogen bonding nature of the solvents. Single exponential decay observed in the SW emission in non-polar solvents suggests that the equilibrium is established between the two rotamers of each molecule. Biexponential decay in the SW emission in polar solvents indicates that the equilibrium is not established between the two rotamers in the S1state. These results are substantiated by the semi-empirical quantum mechanical calculations. The SW emission is assigned to rotamer I and the tail part of the emission is assigned to rotamer IV.

A new fluorescence-quenched ternary complex, Cu²⁺/DMABN/β-CD, has been synthesized using β-cyclodextrin (β-CD), copper ions (Cu²⁺), and 4-(dimethylamino) benzonitrile (DMABN). The significant quenching of DMABN fluorescence is realized through a photoinduced electron-transfer process between DMABN and Cu²⁺. On the basis of the photochemical properties of the ternary complex, we have proposed a Cu²⁺/DMABN/β-CD complex structure with a 2:2:2 molar ratio. To further investigate the ternary complex and explore its potential applications in bioanalysis, we have adopted a novel strategy to restore the quenched fluorescence of DMABN when the complex interacts with an important neurotransmitter, glutamate. The restoration of DMABN fluorescence in the ternary complex is complete and fast upon glutamate interaction. The new complex synthesis and the restoration of the quenched fluorescence processes enable a better understanding of cyclodextrin-based chemistry and also the exploration of novel bioanalysis techniques for neurotransmitters and amino acids. GABA and NMDA have also been used to interact with the ternary complex to restore its fluorescence. Different binding capabilities with the complex show that there are significant differences in binding affinity with different ligand molecules. The new complex and the restoration process will be further explored for bioassays for amino acids and neurotransmitters.

It is shown that the analysis of fusion barrier distributions is not always an unambiguous test or a ‘fingerprint’ of the structure information of the colliding nuclei. Examples are presented with same fusion barrier distributions for nuclei having different structures. The fusion excitation functions for 16O+208Pb, using the coupled reaction channel (CRC) method and correct structure information, have been analysed. The barrier distributions derived from these excitation functions including many of the significant channels are featureless, although these channels have considerable effects on the fusion excitation function. However, a simultaneous analysis of the fusion, elastic and quasi-elastic channels would fix the structure and the reaction unambiguously.

An excited-state intramolecular proton-transfer process has been studied in 2-(2‘-acetamidophenyl)benzimidazole in different solvents using steady-state and time-resolved fluorescence spectroscopy. Semiempirical quantum mechanical calculations have also been carried out. Dual fluorescence (normal and tautomer fluorescence) is observed in all the solvents. On the basis of the fluorescence excitation spectra recorded at different wavelengths and the lifetime data, it is concluded that the normal fluorescence originates from the rotamer trans-II in aprotic solvents and the rotamers trans-II and trans-IV in protic solvents. The tautomer emission originates from the tautomer trans-III in aprotic solvents and tautomers trans-III and trans-III‘ in protic solvents. The presence of an adjacent acetyl group increases the acidity of the N−H (amide proton) bond present in the phenyl ring. This leads to the faster rate of proton transfer in the S1 state. As a result of this, the quantum yield of the tautomer band increases noticeably. With the increase of excitation wavelengths, the ratio of tautomer to normal emission increases in all the solvents. Semiempirical quantum mechanical calculations have shown that the rotamer trans-I is more stable than the rotamer trans-II in the ground state, both under isolated conditions and when dipolar solvation energy is included. Under isolated conditions the activation energy for the interconversion of rotamers is 2.9 kJ mol^-1 in the ground state and 69.2 kJ mol^-1 in the first excited singlet state.

Clinical tests were performed with pollen grains of Datura metel and Cocos nucifera. Both were found to be allergenically potent. The same pollen types were exposed to various concentrations of common gaseous pollutants, namely, SO2 and NOx in a glass chamber for 24, 48 and 72 hours. The gross protein and electrophoretic behaviour of the crude proteins of the pollen grains changed markedly with increase of time and concentration of the relevant gases. Moreover, airborne particulates including those of biological origin were collected from various urban areas of the metropolitan city of Calcutta. The relative distribution of bioparticulates thus collected were quantitatively examined. It is suspected that the natural biopollutants altered their allergenic potentiality with the exposure to various gaseous and chemical pollutants which normally occur in the environment.

An extensive survey of the indoor airborne fungal flora of various working environments was carried out in the Calcutta metropolis for three years (June 1980 to July 1983). Nineteen fungal forms from nine genera were trapped by using Rotorod sampler and exposure culture plate method, then isolated and identified. Spores of Aspergillus were found to occur in highest frequency in all indoor environments, followed by Helminthosporium, Alternaria, Curvularia, Penicillium, Rhizopus, Cladosponum and Candida. The relative concentration of Aspergillus was maximum during the post-monsoon period and minimum during the winter season. All the trapped fungal forms have been proved to be pathogenic and also allergenically potent.

The avalanches in the Abelian sandpile model have a compact structure and consist of shells. The different shells consist solely of sites that have toppled a fixed number of times. For the outermost shell the number is one and increases successively by one from an outer shell to the next inner shell. In this paper, we determine the size-distribution exponents of various categories of sites: sites that have toppled at least once, at least twice, at least thrice, only once and only twice. A particular subclass of avalanches is identified which have no shell structure and consist solely of sites which have toppled only once. The size distribution exponent of this type of clusters is determined.

A rotationally constrained forest fire model is studied on square and triangular lattices of size 400×400. The critical probabilitypc for onset of fire propagation is determined. The scaling relationsM~tdr, Rg~tv andM~Rgdf are analysed at fire propagation probabilityp=pc whereM is the number of burnt trees,Rg the radius of gyration anddf the fractal dimension of the cluster of burnt trees at timet. Numerical estimates ofdt, v anddf have been obtained.