Showing papers by "North Eastern Hill University published in 2000"
TL;DR: Cyanobacteria are an ancient, morphologically diverse group of prokaryotes with an oxygenic photosynthesis as discussed by the authors, and some of them even possess the ability to fix N2.
Abstract: Summary 449
I. INTRODUCTION 450
II. THE PARTNERS 451
1. Cyanobionts and their role 451
2. Hosts and their role 453
3. Location of cyanobionts in their hosts 455
III. INITIATION AND DEVELOPMENT OF SYMBIOSES 458
1. Initiation of symbioses 458
2. Geosiphon pyriforme 458
3. Cyanolichens 459
4. Liverworts and hornworts 460
5. Azolla 460
6. Cycads 461
7. Gunnera 461
IV. THE SYMBIOSES 462
1. Geographical distribution and ecological significance 462
2. Benefits to the partners 462
(a) Benefits to the cyanobionts 462
(b) Benefits to the hosts 463
3. Duration and stability 463
4. Mode of transmission and perpetuation 463
5. Recognition between the partners 464
6. Specificity and diversity 464
7. Symbiosis-related genes 465
8. Modifications of the cyanobiont 466
(a) Growth and morphology 466
(b) Photosynthesis and carbon metabolism 467
(c) Glutamine synthetase 467
(d) Heterocysts 469
(e) N2fixation 470
9. Nutrient exchange 471
(a) Carbon 471
(b) Nitrogen 472
V. EVOLUTIONARY ASPECTS 472
VI. ARTIFICIAL SYMBIOSES 474
VII. FUTURE OUTLOOK AND PERSPECTIVES 475
1. Cryptic symbioses 476
2. Developmental profile of symbiotic tissues 476
3. Sensing and signalling 476
4. Genetic aspects 476
5. Physiological and biochemical aspects of nutrient exchange 477
6. Microaerobiosis 477
7. Potential applications 477
Acknowledgements 477
References 477
Cyanobacteria are an ancient, morphologically diverse group of prokaryotes with an oxygenic photosynthesis. Many cyanobacteria also possess the ability to fix N2. Although well suited to an independent existence in nature, some cyanobacteria occur in symbiosis with a wide range of hosts (protists, animals and plants). Among plants, such symbioses have independently evolved in phylogenetically diverse genera belonging to the algae, fungi, bryophytes, pteridophytes, gymnosperms and angiosperms. These are N2-fixing symbioses involving heterocystous cyanobacteria, particularly Nostoc, as cyanobionts (cyanobacterial partners). A given host species associates with only a particular cyanobiont genus but such specificity does not extend to the strain level. The cyanobiont is located under a microaerobic environment in a variety of host organs and tissues (bladder, thalli and cephalodia in fungi; cavities in gametophytes of hornworts and liverworts or fronds of the Azolla sporophyte; coralloid roots in cycads; stem glands in Gunnera). Except for fungi, the hosts form these structures ahead of the cyanobiont infection. The symbiosis lasts for one generation except in Azolla and diatoms, in which it is perpetuated from generation to generation. Within each generation, multiple fresh infections occur as new symbiotic tissues and organs develop. The symbioses are stable over a wide range of environmental conditions, and sensing–signalling between partners ensures their synchronized growth and development. The cyanobiont population is kept constant in relation to the host biomass through controlled initiation and infection, nutrient supply and cell division. In most cases, the partners have remained facultative, with the cyanobiont residing extracellularly in the host. However, in the water-fern Azolla and the freshwater diatom Rhopalodia the association is obligate. The cyanobionts occur intracellularly in diatoms, the fungus Geosiphon and the angiosperm Gunner a. Close cell–cell contact and the development of special structures ensure efficient nutrient exchange between the partners. The mobile nutrients are normal products of the donor cells, although their production is increased in symbiosis. Establishment of cyanobacterial–plant symbioses differs from chloroplast evolution. In these symbioses, the cyanobiont undergoes structural–functional changes suited to its role as provider of fixed N rather than fixed C, and the level of intimacy is far less than that of an organelle. This review provides an updated account of cyanobacterial–plant symbioses, particularly concerning developments during the past 10 yr. Various aspects of these symbioses such as initiation and development, symbiont diversity, recognition and signalling, structural–functional modifications, integration, and nutrient exchange are reviewed and discussed, as are evolutionary aspects and the potential uses of cyanobacterial–plant symbioses. Finally we outline areas that require special attention for future research. Not only will these provide information of academic interest but they will also help to improve the use of Azolla as green manure, to enable us to establish artificial N2-fixing associations with cereals such as rice, and to allow the manipulation of free-living cyanobacteria for photobiological ammonia or hydrogen production or for use as biofertilizers.
333 citations
01 May 2000-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the authors investigated the potential for improvements in conductivity properties of polymers after 2 MeV electron and 62 MeV proton irradiation and found that the shift in optical absorption edges as observed by UV-VIS spectra of the irradiated polymers has been correlated to the optical band-gap using Tauc's expression.
Abstract: Ion beam treatment studies have been carried out to investigate the potential for improvements in conductivity properties of the polymers Polytetrafluroethylene (PTFE), Polyimide (PI), Polyethyleneterepthalate (PET) and Polypropylene (PP), after 2 MeV electron and 62 MeV proton irradiation. The shift in optical absorption edges as observed by UV–VIS spectra of the irradiated polymers has been correlated to the optical band-gap using Tauc’s expression. A decrease in the optical band-gap has been observed in irradiated PP and PTFE, but no considerable change was found for the optical band-gaps of PET and PI. Further AC conductivity measurements confirmed an increase in conductivity in electron irradiated PP.
170 citations
TL;DR: In this paper, the authors derived new analytic formulas and obtained substantially different numerical predictions for the running masses of quarks and charged leptons at higher scales in the SM, 2HDM and MSSM.
Abstract: Including contributions of scale-dependent vacuum expectation values, we derive new analytic formulas and obtain substantially different numerical predictions for the running masses of quarks and charged-leptons at higher scales in the SM, 2HDM and MSSM. These formulas exhibit significantly different behaviours with respect to their dependence on gauge and Yukawa couplings than those derived earlier. At one-loop level the masses of the first two generations are found to be independent of Yukawa couplings of the third generation in all the three effective theories in the small mixing limit. Analytic formulas are also obtained for running $\tan\beta(\mu)$ in 2HDM and MSSM. Other numerical analyses include study of the third generation masses at high scales as functions of low-energy values of $\tan\beta$ and SUSY scale $M_S=M_Z-10^4$ GeV.
74 citations
TL;DR: A model independent criterion is provided which would guarantee a large flavor mixing of two quasidegenerate Majorana neutrino at the low scale, irrespective of the mixing at the high scale, and it is claimed that for a similar condition to be implementable for the three generation case, the CP parity of one of the neutrinos needs to be opposite to that of the others.
Abstract: We provide a model independent criterion which would guarantee a large flavor mixing of two quasidegenerate Majorana neutrinos at the low scale, irrespective of the mixing at the high scale. We also show that such a situation is realizable for a phenomenologically interesting range of parameters of the weak scale theory. We further claim that for a similar condition to be implementable for the three generation case, the CP parity of one of the neutrinos needs to be opposite to that of the others.
71 citations
TL;DR: An efficient method for the synthesis of biologically important 2,3-functionalized imidazo[1,2-a]pyridines has been described via an unprecedented CuCl2-induced oxidative ring closure of novel R-oxoketene N,S, N,O, and N,N-acetal intermediates, which can be prepared with large structural variations from various aminoheterocycles, thus broadening the scope of this methodology.
Abstract: ion of hydrogen via cation radical intermediate 14 may give resonance stabilized aminyl radical 15 which undergoes facile intramolecular addition to the enamine double bond followed by abstraction of a hydrogen radical or proton to give the final product. Alternatively, electron transfer from nitrogen to Cu(II) ion may take place in the coordination sphere of initially formed copper complex of type 17 to give metal-complexed aminyl radical intermediate 1828 which on subsequent intramolecular cyclization may afford imidazo[1,2-a]pyridines (Scheme 6). Cuprous and cupric salts in the presence of oxygen and pyridine or amines are known to act as useful oxidizing systems for cleavage of hydrazides,29 bishydrazone,30 o-phenylenediamine,31 and for dimerization of aromatic amines.32 We are further exploring the mechanism of this novel oxidative cyclization with CuCl2 and its application for construction of other fused heterocycles. In summary, an efficient method for the synthesis of biologically important 2,3-functionalized imidazo[1,2-a]pyridines has been described via an unprecedented CuCl2-induced oxidative ring closure of novel R-oxoketene N,S-, N,O-, and N,N-acetal intermediates. The methodology allows regiospecific introduction of alkylthio, alkoxy, primary, and secondary amino group in the 2-position of imidazopyridine ring. These functionalities can be further elaborated to construct novel fused heterocyclic ring systems. The other advantages include mild reaction conditions and easy accessibility of N,S-, N,O-, and N,Nacetals, which can be prepared with large structural variations from various aminoheterocycles, thus broadening the scope of this methodology for the synthesis of diverse class of bridgehead nitrogen heterocycles. Experimental Section General. n-Butyllithium (2.5 M in hexane) was purchased from Aldrich Chemical Co. Cu(II)Cl2 (AR grade, moisture free) and BF3‚Et2O were purchased from E-Merck India. Benzene (AR grade) was purchased from Glaxo and used directly. Tetrahydrofuran (THF) was distilled twice over sodium/benzophenone and stored on sodium wire before use. Unless otherwise stated all reagents were purchased from local commercial sources and used without purification. All the R-oxoketene N,S(2a-f) and N,N(3a-d) acetals were prepared according to our reported26 procedure by reacting 2-(lithioamino)pyridine with corresponding R-oxoketenedithioacetals. 1-(4-Methylphenyl)-3,3-bis-(2-pyridylamino)prop-2-en-1one (3b): light yellow crystals; mp 102-103 °C; 1H NMR (400 MHz, CDCl3) δ 2.35 (s, 3H), 6.79-6.82 (m, 1H), 6.88-6.93 (m, 2H), 7.01 (d, 1H, J ) 8.0 Hz), 7.17 (s, 1H), 7.20 (d, 2H, J ) 8.4 Hz), 7.50-7.58 (m, 2H), 7.85 (d, 2H, J ) 8.4 Hz), 8.12-8.13 (m, 1H), 8.38-8.40 (m, 1H), 12.98 (brs, 1H), 14.59 (brs, 1H); 13C NMR (CDCl3) δ 21.0, 80.4, 113.5, 114.8, 117.0, 118.2, 126.6, 128.5, 137.3, 137.6, 138.1, 140.4, 145.4, 148.0, 151.9, 154.1, 155.4, 180.6; IR (KBr) 3450, 1640, 1600, 1585, 1545 cm-1; MS m/z (%) 330 (M+, 56). Anal. Calcd for C20H18N4O: C, 72.71; H, 5.49; N, 16.96. Found: C, 72.96; H, 5.28; N, 16. 85. 1-(4-Chlorophenyl)-3,3-bis-(2-pyridylamino)prop-2-en-1one (3c): yellow crystals; mp 111-112 °C; 1H NMR (400 MHz, CDCl3) δ 6.95-6.98 (m, 1H), 7.01-7.06 (m, 2H), 7.13 (s, 1H), 7.14 (d, 1H, J ) 8.2 Hz), 7.38 (d, 2H, J ) 8.4 Hz), 7.66-7.73 (m, 2H), 7.85 (d, 2H, J ) 8.0 Hz), 8.25 (d, 1H, J ) 4.8 Hz), 8.48 (d, 1H, J ) 4.4 Hz), 13.12 (brs, 1H), 14.54 (brs, 1H); 13C NMR (CDCl3) δ 80.7, 114.3, 115.6, 117.7, 119.0, 128.4, 136.5, 137.9, 138.8, 139.2, 145.9, 148.6, 152.2, 154.6, 156.4, 185.8; IR (KBr) 3400, 1655, 1610, 1580, 1540 cm-1; MS m/z (%) 350 (M+, 60). Anal. Calcd for C19H15ClN4O: C, 65.05; H, 4.31, N, 15.97. Found: C, 65.25; H, 4.21; N, 15.67. General Procedure for the Preparation of N,O-Acetals (4c,d). To a stirred solution of methanolic sodium methoxide (prepared from 0.46 g of Na metal in 15 mL of dry methanol, 15 mmol) was added the respective N,S-acetal (10 mmol) dissolved in 15 mL of dry methanol, and the reaction mixture was stirred at room temperature for 10 min, followed by refluxing for 2 h. It was cooled to room temperature, quenched with saturated NH4Cl solution, and extracted with chloroform. The combined extracts were washed with water, dried (Na2SO4), and evaporated to give the crude N,O-acetals, which were purified by column chromatrography over silica gel using hexane/ethyl acetate (9:1) as eluent. 1-(4-Chlorophenyl)-3-methoxy-3-(2-pyridylamino)prop2-en-1-one (4c): light yellow crystals; mp 137-138 °C; 1H NMR (400 MHz, CDCl3) δ 3.90 (s, 3H), 5.60 (s, 1H), 6.90 (m,1H), 7.40 (d, 2H, J ) 9.0 Hz), 7.50-7.75 (m, 2H), 7.95 (d, 2H, J ) 9.0 Hz), 8.35 (dd, 1H, J ) 6.9, 1.8 Hz), 14.56 (brs, 1H); 13C NMR (CDCl3) δ 46.5, 90.6, 114.5, 118.5, 128.5, 128.6, 137.3, 138.0, 138.4, 146.0, 152.2, 166.6, 184.5; IR (KBr) 3417, 1617, 1589, 1213; MS m/z (%): 288 (M+, 80); Anal. Calcd for C15H13ClN2O2: C, 62.39; H, 4.53; N, 9.70. Found: C, 62.45; H, 4.42; N 9.61. (28) (a) Esker, J. L.; Newcomb, M. Adv. Heterocycl. Chem. 1993, 58, 1. (b) Falles, A. G.; Bniuza, I. M. Tetrahedron 1997, 53, 17543-17594 and references therein. (c) Baslable, J. W.; Hobson, J. D.; Ridell, W. D. J. Chem. Soc., Perkin Trans. 1 1972, 2205. (d) Broka, C. A.; Eng, K. K. J. Org. Chem. 1986, 51, 5043. (29) Tsuji, J.; Nagashima, T.; Qui, N. T.; Takayanagi, H. Tetrahedron 1980, 36, 1311-1315. (30) Tsuji, J.; Takahashi, H.; Kajimoto, T. Tetrahedron Lett. 1973, 4573-4574. (31) (a) Tsuji, J.; Takayanagi, H.; Toshida, Y. Chem. Lett. 1976, 147148. (b) Kajimoto, T.; Takahashi, H.; Tsuji, J. J. Org. Chem. 1976, 41, 1389-1393. (32) (a) Kajimoto, T.; Takahashi, H.; Tsuji, J. Bull. Chem. Soc. Jpn. 1982, 55, 3673. (b) Jackisch, J.; Legler, J.; Kauffmann, T. Chem. Ber. 1982, 115, 659. Scheme 5 Scheme 6 Notes J. Org. Chem., Vol. 65, No. 5, 200
59 citations
TL;DR: In this paper, the N-methyl quaternary salt (NMS) was used as transfer reagent for the synthesis of dithiocarbamates, symmetrical and unsymmetrical mono-, di-and tri-substituted thioureas in high yields under mild and simple nonhazardous reaction conditions.
56 citations
TL;DR: In this paper, the neutrino mixing pattern with the large mixing required for the atmospheric neutrinos problem and the small mixing angle MSW solver was shown to be optimal.
44 citations
TL;DR: Owing to these physiological adaptive strategies related to amino acid metabolism along with the presence of a functional and regulatory urea cycle, it is believed that this catfish is able to survive in very high ambient ammonia or in the air and in the mud during habitat drying.
Abstract: The changes in the free amino acid (FAA) levels, the rate of efflux of FAAs from the perfused liver, and the activity of some enzymes related to amino acid metabolism such as glutamate dehydrogenase (GDH, both reductive amination and oxidative deamination), glutamine synthetase (GS), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were studied in the liver of a freshwater air-breathing teleost, the walking catfish, Clarias batrachus, perfused with 5 and 10 mM NH(4)Cl. The level of the various non-essential FAAs increased significantly, with a total increase of about 150%, which was accompanied by a significant increase of both ammonia and urea-N in the perfused liver both with 5 and 10 mM NH(4)Cl. The rate of efflux of these non-essential FAAs from the perfused liver also increased significantly with a total increase of about 115% and 160% at 5 and 10 mM NH(4)Cl, respectively. The activity of the mentioned amino acid metabolism-related enzymes in the perfused liver also got stimulated, except for GDH in the ammonia forming direction and ALT, under a higher ammonia load. The activity (both tissue and specific) of GDH in the glutamate forming direction increased maximally, followed by AST and GS in a decreasing order. Owing to these physiological adaptive strategies related to amino acid metabolism along with the presence of a functional and regulatory urea cycle (reported earlier), it is believed that this catfish is able to survive in very high ambient ammonia or in the air or in the mud during habitat drying.
43 citations
TL;DR: It is suggested that the cisplatin-induced biochemical changes in mitochondria involving mitochondrial protein, glutathione, and succinate dehydrogenase could be the important potent cellular sites contributing to toxicity/cytotoxicity after cisPlatin treatment.
Abstract: Cisplatin treatment of tumor-bearing mice resulted a significant decrease of protein in the tissues studied (liver, kidney, and Dalton lymphoma) and also in their mitochondrial fractions. As compared to respective tissues, the protein decrease was noted to be more conspicuous in their mitochondrial fractions. Similarly, mitochondrial glutathione also decreased significantly in the tissues. However, succinate dehydrogenase activity was selectively decreased in the kidney and Dalton lymphoma cells, whereas in liver it remained almost unchanged. An increase in serum urea concentration and kidney mitochondrial lipid peroxidation was also observed after cisplatin treatment. It is suggested that the cisplatin-induced biochemical changes in mitochondria involving mitochondrial protein, glutathione, and succinate dehydrogenase could be the important potent cellular sites contributing to toxicity/cytotoxicity after cisplatin treatment.
41 citations
TL;DR: In all the four tree species, biomass of both fine- and coarse-roots followed a unimodal growth curve by showing a gradual increase from spring (pre-rainy) season to autumn (post rainy) season, which may be advantageous for sequential or spatially separated agroforestry systems.
Abstract: An understanding of the rooting pattern of tree species used in agroforestry systems is essential for the development and management of systems involving them. Seasonal variation, depth wise and lateral distribution of biomass in roots of different diameter classes and their annual production were studied using sequential core sampling. The investigations were carried out in four tree species under ‘tree only’ and ‘tree+crop’ situations at ICAR Research Farm, Barapani (Meghalya), India. The tree species were mandarin (Citrus reticulata), alder (Alnus nepalensis), cherry (Prunus cerasoides) and albizia (Paraserianthes falcataria). The contribution of fine roots to the total root biomass ranged from 87% in albizia to 77% in mandarin. The bulk of the fine roots (38% to 47%) in the four tree species was concentrated in the upper 10 cm soil layer, but the coarse roots were concentrated in 10–20 cm soil depth in alder (46%) and albizia (51%) and at 0–10 cm in cherry (41%) and mandarin (48%). In all the four tree species, biomass of both fine- and coarse-roots followed a unimodal growth curve by showing a gradual increase from spring (pre-rainy) season to autumn (post rainy) season. Biomass to necromass ratio varied between 2 to 3 in the four tree species. The maximum (3.2) ratio was observed during spring and the minimum (2) in the rainy season. In alder and albizia, the fine roots were distributed only up to 1 m distance from the tree trunk but in the other two species they were found at a distance up to 1.5 m from the tree trunk. The annual fine root production varied from 3.6 Mg ha−1 to 6.2 Mg ha−1 and total production from 4.2 to 8.4 Mg ha−1 in albizia to mandarin, respectively. Cherry and mandarin had a large number of woody roots in the surface layers which pose physical hindrance during soil working and intercultural operations under agroforestry. But the high biomass of roots of these two species may be advantageous for sequential or spatially separated agroforestry systems. However, alder and albizia have the most desirable rooting characteristics for agroforestry systems.
31 citations
TL;DR: In this article, the authors consider the zero-temperature single-spin-flip dynamics of the random-field Ising model on a Bethe lattice in the presence of an external field h and derive the exact self-consistent equations to determine the distribution Prob(s) of avalanche sizes s as the external field increases from −∞ to ∞.
Abstract: We consider the zero-temperature single-spin-flip dynamics of the random-field Ising model on a Bethe lattice in the presence of an external field h. We derive the exact self-consistent equations to determine the distribution Prob(s) of avalanche sizes s as the external field increases from −∞ to ∞. We solve these equations explicitly for a rectangular distribution of the random fields for a linear chain and the Bethe lattice of coordination number z=3, and show that in these cases, Prob(s) decreases exponentially with s for large s for all h on the hysteresis loop. We find that for z≥4 and for small disorder, the magnetization shows a first-order discontinuity for several continuous and unimodal distributions of the random fields. The avalanche distribution Prob(s) varies as s−3/2 for large s near the discontinuity.
TL;DR: Various purine analogs such as inosine, purine, α-adenosine and adenine showed variable inhibitions on the activity of ADA, and the purified enzyme was more stable in the alkaline pH.
Abstract: Adenosine deaminase (ADA) was isolated from small intestine of mice and purified to utmost homogeneity. SDS-PAGE of purified ADA gave a molecular weight of 41 kDa. Western blot analyses gave a single reactive band at 41 kDa and the other band was an associated ADA binding protein. The purified enzyme was more stable in the alkaline pH. The optimum pH and the pI values were about 7.0 and 4.96, respectively. Km values of the small intestinal ADA for adenosine and 2′-deoxyadenosine were 23 and 16μM, respectively. Purine riboside was a competitive inhibitor with Ki of 5 μM, whereas 2′-3′-o-isopropylidene adenosine acted as an uncompetitive inhibitor (Ki 66 μM). Activity of ADA was inhibited by the presence of theophylline (-40%), caffeine (-30%), and L-cysteine (-50%). Significantly, Hg2+ (100 μM) inhibited 98% of the initial ADA activity. In addition, various purine analogs such as inosine, purine, α-adenosine and adenine showed variable inhibitions on the activity of ADA. Relative ADA activity towards 3′-deoxyadenosine and 6-chloropurine riboside was lower by 30% and 40%, respectively. However, the activity towards 2′-o-methyl adenosine was higher (30%) compared to the activity obtained using adenosine.
TL;DR: In this article, a new Na+ ion conducting composite polymer electrolytes comprising of polyethylene oxide (PEO)-NaClO4 and PEO-NaI complexes dispersed with SnO2 are reported.
Abstract: New Na+ ion conducting composite polymer electrolytes comprising of polyethylene oxide (PEO)-NaClO4 and PEO-NaI complexes dispersed with SnO2 are reported. The results of the studies based on optical microscopy, X-ray diffraction (XRD), differential scanning calorimetry (DSC), Fourier transform infra-red (FTIR) spectroscopy, impedance analysis and mechanical testing are presented and discussed. The electrical conductivity of ≈5·10−5 S·cm−1 at 40 °C was achieved for the dispersion of ≈10 wt.% of SnO2 in both systems. The composition dependence of the conductivity has been well correlated with the variation in glass transition temperature and degree of crystallinity. A substantial enhancement in the mechanical properties of the composite films was observed at the cost of slight decrease in the conductivity at higher concentration of SnO2. The temperature dependence of the conductivity follows apparently the Arrhenius type thermally activated process below and above the melting temperature of PEO. The conductivity of the materials has been found to be strongly humidity dependent. The materials are shown to be ionic with tion>0.9. The electrochemical stability of the materials has been observed to be up to ≈3.2 V for (PEO)25NaClO4+x% SnO2 and is limited to ≈1.9 V for (PEO)25NaI+x% SnO2.
TL;DR: Minor hysteresis loops within the main loop are obtained exactly in the one-dimensional ferromagnetic random-field Ising model at zero temperature.
Abstract: Minor hysteresis loops within the main loop are obtained exactly in the one-dimensional ferromagnetic random-field Ising model at zero temperature. Numerical simulations of the model show excellent agreement with the exact results.
TL;DR: Spectroscopically investigated interactions of three 5-(aryl)azoquinolin-8-ol derivatives, which could be used as potent chelate forming agents, with bovine serum albumin (BSA), and demonstrated that the azo group nitrogen adjacent to the phenyl ring probably participated in the formation of a BSA-CPAQ complex.
TL;DR: In this article, a mixed electrolyte model has been used to compute the micellization parameters, viz., critical micelle concentration, aggregation number, and counterion binding constant, from the conductance data.
Abstract: Electrical conductances of solutions of sodium dodecyl sulfate (SDS) and cetylpyridinium chloride (CPC) in acetamide melt were measured at 89 °C as a function of concentration. The dependence of molal conductance of SDS and CPC on concentration has been compared with that of normal electrolytes in acetamide melt. Both SDS and CPC are found to micellize in acetamide melt. A mixed electrolyte model has been used to compute the micellization parameters, viz., critical micelle concentration, aggregation number, and counterion binding constant, from the conductance data. Surface potentials of the micelles were computed by solving the nonlinearized Poisson−Boltzmann equation. The free energy terms for micellization were also evaluated.
TL;DR: The time dependence of the uptake of NaOH/LiOH etchant in pristine polycarbonate (PC) and in PC irradiated with 3 GeV Pb ions has been examined in this paper.
Journal Article•
TL;DR: The findings suggest that in C. batrachus MIT and DIT may be more important than T3 and T4 at low temperature, endogenous thyroid hormones are involved indirectly in energy metabolism even during winter/at low temperature and testicular hormones are actively involved in the respiration.
Abstract: In vivo and in vitro effects of thyroidal hormones (MIT, DIT, T3, T4), propyl thiouracil (PTU), testosterone and cyproterone acetate were studied on the rate of tissue (liver, muscle, kidney and brain) respiration of adult male C. batrachus during winter and summer/rainy seasons. Monoiodotyrosine (MIT) and diiodothyrosine (DIT) increased the respiratory rate in a dose-dependent and temperature-independent manner. Triiodothyronine (T3) and thyroxine (T4) stimulated tissue respiration during summer/rainy months but not during winter. PTU decreased tissue respiration during summer/rainy season and also at simulated low temperature. Testosterone invariably stimulated the rate of respiration of the tissues, while in vivo treatment with cyproterone acetate significantly decreased the metabolic rate of all the tissues. The findings suggest that in C. batrachus MIT and DIT may be more important than T3 and T4 at low temperature, endogenous thyroid hormones are involved indirectly in energy metabolism even during winter/at low temperature and testicular hormones are actively involved in the respiration.
TL;DR: In this paper, the modification in particle track etching response of polyallyl diglycol carbonate (PADC) due to impact of 2 MeV electrons was investigated.
Abstract: In the present work, attempts have been made to investigate the modification in particle track etching response of polyallyl diglycol carbonate (PADC) due to impact of 2 MeV electrons. PADC samples pre-irradiated to 1, 10, 20, 40, 60, 80 and 100 Mrad doses of 2 MeV electrons were further exposed to 140 MeV28 Si beam and dose-dependent track registration properties of PADC have been studied. Etch-rate values of the PADC irradiated to 100 Mrad dose electron was found to increase by nearly 4 times that of pristine PADC. The electron irradiation has promoted chain scissioning in PADC, thereby converting the polymer into an easily etchable polymer. Moreover, the etching response and the detection efficiency were found to improve by electron irradiation. Scanning electron microscopy of etched samples further revealed the surface damage in these irradiated PADCs.
TL;DR: In this article, the simultaneous formation of mono-and dication radicals during the photo-oxidation of free-base tetraphenylporphin by selective laser excitations using resonance Raman and optical absorption techniques was reported.
TL;DR: The effects of scale dependent vacuum expectation values (VEVs) on the running masses of quarks and leptons in non-SUSY gauge theories have been considered by a number of authors as mentioned in this paper.
Abstract: The effects of the scale dependent vacuum expectation values (VEVs) on the running masses of quarks and leptons in non-SUSY gauge theories have been considered by a number of authors. Here we use RGEs of the VEVs, and the gauge and Yukawa couplings in the MSSM to analytically derive new one loop formulas for the running masses above the SUSY breaking scale. Some of the masses exhibit a substantially different behaviour with respect to their dependence on the gauge and Yukawa couplings when compared with earlier formulas in the MSSM derived ignoring RGEs of VEVs. In particular, the masses of the first two generations are found to be independent of the Yukawa couplings of the third generation in the small mixing limit. New numerical estimates at the two loop level are also presented.
TL;DR: In this article, the optical energy gap of a specially prepared zinc phosphate glass (ZnP) was studied as a function of gamma dose and the optical absorption spectra in the wavelength region of 200-800 nm were recorded for pristine ZnP glass sample and a number of samples exposed to different γ -doses in the range 10 0 -10 6 ǫ.
TL;DR: In this article, self-associative hydrogen-bonded pairs arising from a substituted pyrrole, a substituted imidazole, substituted iminidazoles, substituted Pyridines, pyrimidines and pyrazines are studied using the semi-empirical PM3 SCF-MO method.
Abstract: Self-associative hydrogen-bonded pairs arising from a substituted pyrrole, a substituted imidazole, substituted pyridines, pyrimidines and pyrazines are studied using the semiempirical PM3 SCF-MO method. The search for a set of self-associative base-pairs mimicking the characteristics and functionality of DNA bases led to the identification of three imidazole pairs as possible candidates. Pairs with oxygen rather than fluorine as the electronegative atom are in general more stable.
TL;DR: Using higher-derivative gravitational action in (4+D)-dimensional space-time, Lagrangian density of riccion is obtained with the quartic self-interacting potential as mentioned in this paper.
Abstract: Using higher-derivative gravitational action in (4+D)-dimensional space–time, Lagrangian density of riccion is obtained with the quartic self-interacting potential. It is found that after compactification to four-dimensional space–time the resulting theory for riccions is one-loop multiplicatively renormalizable. Renormalization group equations are solved and its solutions yield many interesting results such as (i) dependence of extra dimensions on the energy mass scale showing that these dimensions increase with the increasing mass scale, (ii) phase transition at 1.76×1016 GeV and (iii) dependence of gravitational and other coupling constants on energy scale. Results also suggest that space–time above 1.76×1016 GeV should be fractal.
Journal Article•
TL;DR: A novel protein from plants that can be utilised for various therapeutical treatments ranging from cancers, AIDS and other viral diseases of present times is witnessed.
Abstract: Ribosome inactivating proteins (RIPs) are a group of naturally occurring plant proteins with a RNA-N-glycosidases activity which depurinate rRNA at a specific universally conserved position (i.e. cleavage of N-glycosidic bond of a specific adenine of 28S rRNA). These proteins are found in different parts of plants, in concentrations ranging from a few micrograms to several hundred mg per 100 g of plant tissues. RIPs exist in two forms, type 1 having a single polypeptide chain with a molecular mass of approximately 30 kDa possessing N-glycosidase activity; and type 2 with two or four polypeptide chains having a molecular mass of approximately 60 kDa and approximately 120 kDa respectively showing lectin activity along with N-glycosidase moiety. Such biomolecules causing cytotoxicity are being exploited for designing immunotoxins/hormonotoxins using heterobifunctional conjugates. These carrier conjugates with the RIPs can influence cellular trafficking and inhibition of protein synthesis. We are witnessing a novel protein from plants that can be utilised for various therapeutical treatments ranging from cancers, AIDS and other viral diseases of present times.
TL;DR: Findings reveal tissue- and age- specific variations in the level of GR that is not influenced under diabetic conditions, however, the activation of hepatic GR is reduced during STZ-induced diabetes that might play a role in controlling glucose homeostasis in diabetic animals.
Journal Article•
TL;DR: Results of the analysis show that the socio-economic background variables influence the use of libraries and information centres of scientists and technologists in Bangladesh.
Abstract: Scientists and technologists are major users of libraries and information centres. This paper studies their usage pattern by considering the influence of their background variables, namely, age, gender, qualifications and status. The study sample population consists of 246 scientists and technologists from two major scientific and technical research institutes in Bangladesh. One-way analysis of variance (ANOVA) statistical test was used to test the hypotheses and the results of the analysis show that the socio-economic background variables influence the use of libraries and information centres.
TL;DR: In this paper, the neutrino mixing pattern with the large mixing required for the atmospheric neutrinos problem and the small mixing angle MSW solution for the solar neutrer problem can be naturally generated through radiative magnification, even though all the mixing angles at the seesaw scale may be small.
Abstract: We show that the neutrino mixing pattern with the large mixing required for the atmospheric neutrino problem and the small mixing angle MSW solution for the solar neutrino problem can be naturally generated through radiative magnification, even though all the mixing angles at the seesaw scale may be small. This can account for the neutrino anomalies as well as the CHOOZ constraints in the context of quark-lepton unified theories, where the quark and lepton mixing angles are expected to be similar in magnitude at the high scale. We also indicate the 4$
u$ mixing scenarios for which this mechanism of radiative magnification can provide a natural explanation.
TL;DR: The title compound, C14H12N2O4 as discussed by the authors, shows an E conformation about the diazenyl N atoms, and the crystal structure features layers of mol-ecules with the primary connection between the layers afforded by carboxyl-ic acid dimer motifs.
Abstract: The title compound, C14H12N2O4, shows an E conformation about the diazenyl N atoms. The crystal structure features layers of molecules with the primary connection between the layers afforded by carboxylic acid dimer motifs; no evidence for extensive π–π stacking between the layers was found.
TL;DR: In this article, the Mathieu potential is used to define the crystal potential from which the initial state wavefunction for the surface state is derived, which is used for photoemission calculations in the case of free electron metals like Al and Be.