Fragment angular momenta in low and medium energy fission of242Pu

Independent isomeric yield ratios of¹²⁸Sb were determined radiochemically in the thermal neutron induced fission of²⁴¹Pu and 34 MeV alpha particle induced fission of²³⁸U, both involving the same compound nucleus (²⁴²Pu). Fragment angular momenta estimated from the measured isomer ratios using the statistical model analysis showed significantly larger fragment angular momenta in the medium energy fissioning system compared to the low energy fissioning system. This has been attributed to the effect of higher excitation energy and angular momentum in the entrance channel leading to increased fragment temperature, moments of inertia and angular velocity. An attempt was made to calculate the fragment angular momentum in the medium energy fission using the Fermi gas model for the fissioning nucleus, taking into account the multichance fission, saddle shapes of the fissioning nuclei and the angular velocity components of the fissioning nuclei both along and orthogonal to the fission axis. The calculated angular momenta agree well with the experimental results.     

Anti-inflammatory chromone alkaloids and glycoside from Dysoxylum binectariferum

Herein we report isolation of a new chromone alkaloid chrotacumine K (12) from fruits and a chromone glycoside schumaniofioside A (13) from leaves of Dysoxylum binectariferum Hook f. Schumaniofioside A is reported for the first time from Meliaceae family. Other known alkaloids isolated include rohitukine (1) and chrotacumine E (6). The structure of new alkaloid 12 was elucidated on the basis of extensive 1D and 2D NMR analysis, synthesis and chemical hydrolysis. Chemically, chrotacumine K (12) is a 3′-O-acetyl rohitukine which on chemical or enzymatic hydrolysis produces rohitukine. The new alkaloid 12 is also present in seeds and stem-barks of this plant. The glycoside schumaniofioside A (13) is present only in leaves, and in abundance (～1% w/w of dried leaves). The isolated compounds and extracts were evaluated for in vitro effect on the proinflammatory cytokines (TNF-α and IL-6) in human monocytic THP-1 cells. The alkaloid 12 displayed potent inhibition (57%) of TNF-α at 0.3 µM, and was non-toxic to THP-1 cells up to 40 µM, indicating its excellent therapeutic window. Furthermore, a nitrobenzoyl ester analog 15e showed better inhibition of IL-6 than parent natural product chrotacumine K.     

Sedimentation analysis of organic–inorganic hybrid colloids

Hybrid organic–inorganic latex particles are synthesized to combine the beneficial properties of the constituents which thus lead to synergistic improvement in the properties. The properties of hybrid particles are dependent on the successful hybridization process, thus controlling or tuning of such processes by effective characterization is immensely important. Analytical ultracentrifugation provides these characterization possibilities owing to its high statistical capability and ability to characterize multiple parameters. The use of different detection methodologies can help in generating valuable information on the overall size and density distributions of the particles. Apart from that, it is also possible to quantify the presence of any free polymer and inorganic particles in the hybrid latex which would affect the properties of hybrid latexes. By following the densities of the pure and hybrid particles, it is also possible to quantify the amounts of the constituent phases in the hybrid particles. The density gradients generated in preparative ultracentrifugation also provide additional possibilities for the characterization of the hybrid particles which have densities higher than the measurable range in the analytical ultracentrifuge. Evolution of hybrid particles can also be studied as a function of time. It also provides advantage of separation of the various fractions for further characterization.     

Effect of phenyl group on the structure and formation of transitional alumina from Al (OPh)<Subscript>3</Subscript>

The structure of freshly prepared Al(OPh)₃, its decomposition product, the hydrolyzed products and their structural evolution were investigated employing ²⁷Al MAS NMR spectroscopy, PXRD, TGA/DTA/DSC/FTIR techniques. In the ²⁷Al MAS NMR spectrum of the aluminium phenoxide, three signals with the chemical shift at 3.78, 21 and 45 ppm were observed. The chemical shift at 3.78 and 45 ppm revealed the presence of four and sixfold coordinated aluminum. The signal at 21 ppm corresponded to fivefold coordinated aluminium. When the aluminium phenoxide was directly decomposed in air at 600 °C, it resulted in amorphous product as evidenced from the PXRD pattern. The observed signals with chemical shifts at 10.1, 42, 73.6 ppm in the ²⁷Al MAS NMR spectrum indicated the presence of 6, 5 and 4 coordination for the aluminium atoms suggesting disordered transitional γ-alumina to be the product. The hydrolysis studies of Al(OPh)₃ with excess of water at 70 °C yielded bohemite (γ-AlOOH). The alumina obtained after dehydration at 600 °C was X-ray amorphous. The dehydrated product at 600 °C showed the presence of four and six coordinated aluminium atoms in the ²⁷Al MAS NMR spectrum confirming it to be ordered γ-Al₂O₃. Crystalline γ-Al₂O₃ was obtained on further heating at 800 °C.     

Effect of Additives on the Activity of Tannase from <Emphasis Type="Italic">Aspergillus awamori</Emphasis> MTCC9299

Tannase from Aspergillus awamori MTCC 9299 was purified using ammonium sulfate precipitation followed by ion-exchange chromatography. A purification fold of 19.5 with 13.5% yield was obtained. Temperature of 30 °C and pH of 5.5 were found optimum for tannase activity. The effects of metals and organic solvents on the activity of tannase were also studied. Metal ions Mg⁺², Mn⁺², Ca⁺², Na⁺, and K ⁺ stimulated the tannase activity, while Cu⁺², Fe⁺³, and Co⁺² acted as inhibitors of the enzyme. The addition of organic solvents like acetic acid, isoamylalcohol, chloroform, isopropyl alcohol, and ethanol completely inhibited the enzyme activity. However, butanol and benzene increased the enzyme activity.     

Complementary and Comparative Study on Hypoglycemic and Antihyperglycemic Activity of Various Extracts of Eugenia jambolana Seed, Momordica charantia Fruits, Gymnema sylvestre, and Trigonella foenum graecum Seeds in Rats

In present study, we investigated hypoglycemic and antihyperglycemic potential of five extracts (water, ethanol, methanol, hexane, and chloroform) of four plants (i.e., seeds of Eugenia jambolana, fruits of Momordica charantia, leaves of Gymnema sylvestre, and seeds of Trigonella foenum graecum) alone and/or in combination with glimepiride in rats. Ethanol extract of E. jambolana, water extract of M. charantia, ethanol extract of G. sylvestre, and water extract of T. graecum exhibited highest hypoglycemic and antihyperglycemic activity (most active) in rats among all the extracts, while hexane extracts exhibited least activities. Most active extracts were further studied to dose-dependent (200, 100, and 50 mg/kg body weight (bw)) hypoglycemic and antihyperglycemic effects alone and in combination with glimepiride (20, 10, and 5 mg/kg bw). The combination of most active extracts (200 mg/kg bw) and lower dose of glimepiride (5 mg/kg bw) showed safer and potent hypoglycemic as well as antihyperglycemic activities without creating severe hypoglycemia in normal rats, while higher doses (200 mg/kg bw of most active extracts, and 10 and 20 mg/kg bw of glimepiride) were generated lethal hypoglycemia in normal rats. From this study, it may be concluded that the ethanol extract of E. jambolana seeds, water extract of M. charantia fruits, ethanol extract of G. sylvestre leaves, and water extract of T. graecum seeds have higher hypoglycemic and antihyperglycemic potential and may use as complementary medicine to treat the diabetic population by significantly reducing dose of standard drugs.     

Recovery and pre-concentration of americium (III) from dilute acid solutions using an emulsion liquid membrane containing di-2-ethylhexyl phosphoric acid (D2EHPA) as extractant

Radiochemical results of U isotopes (²³⁴U, ²³⁵U and ²³⁸U) and their activity ratios are reported for well waters as local sources of drinking waters collected from the ten settlements around the Semipalatinsk Nuclear Test Site (SNTS), Kazakhstan. The results show that ²³⁸U varies widely from 3.6 to 356 mBq/L (0.3–28.7 μg/L), with a factor of about 100. The ²³⁸U concentrations in some water samples from Dolon, Tailan, Sarzhal and Karaul settlements are comparable to or higher than the World Health Organization’s restrictive proposed guideline of 15 μg (U)/L. The ²³⁴U/²³⁸U activity ratios in the measured water samples are higher than 1, and vary between 1.1 and 7.9, being mostly from 1.5 to 3. The measured ²³⁵U/²³⁸U activity ratios are around 0.046, indicating that U in these well waters is of natural origin. It is probable that the elevated concentration of ²³⁸U found in some settlements around the SNTS is not due to the close-in fallout from nuclear explosions at the SNTS, but rather to the intensive weathering of rocks including U there. The calculated effective doses to adults resulting from consumption of the investigated waters are in the range 1.0–18.7 μSv/y. Those doses are lower than WHO and IAEA reference value (100 μSv/y) for drinking water.     

Spectral beam combining of 2 μm Tm fiber laser systems

Output beams from three independently frequency-stabilized thulium master-oscillator power-amplifier fiber laser systems were spectrally combined using a plane-ruled metal diffraction grating. Two laser channels were frequency-stabilized with guided mode resonance filters and the third was stabilized using a plane-ruled metal diffraction grating. The systems had output wavelengths between 1984 and 2015 nm, each with a spectral width of 100-450 pm and output powers between 40-120 W. The combined beam had powers up to 49 W and was 32% efficient with respect to the launched pump power.     

Quantum fluid dynamics based current-density functional study of a helium atom in a strong time-dependent magnetic field

Evolution of the helium atom in a strong time-dependent (TD) magnetic field (B) of strength up to 10¹¹ G is investigated through a quantum fluid dynamics (QFD) based current-density functional theory (CDFT). The TD-QFD-CDFT computations are performed through numerical solution of a single generalized nonlinear Schr?dinger equation employing vector exchange-correlation potentials and scalar exchange-correlation density functionals that depend both on the electronic charge-density and the current-density. The results are compared with that obtained from a B-TD-QFD-DFT approach (based on conventional TD-DFT) under similar numerical constraints but employing only scalar exchange-correlation potential dependent on electronic charge-density only. The B-TD-QFD-DFT approach, at a particular TD magnetic field-strength, yields electronic charge- and current-densities as well as exchange-correlation potential resembling with that obtained from the time-independent studies involving static (time-independent) magnetic fields. However, TD-QFD-CDFT electronic charge- and current-densities along with the exchange-correlation potential and energy differ significantly from that obtained using B-TD-QFD-DFT approach, particularly at field-strengths >10⁹ G, representing dynamical effects of a TD field. The work concludes that when a helium atom is subjected to a strong TD magnetic field of order >10⁹ G, the conventional TD-DFT based approach differs “dynamically” from the CDFT based approach under similar computational constraints.     

Experimental investigation on the flow instability behavior of a multi-channel boiling natural circulation loop at low-pressures

Natural circulation as a mode of heat removal is being considered as a prominent passive feature in the innovative nuclear reactor designs, particularly in boiling-water-reactors, due to its simplicity and economy. However, boiling natural circulation system poses many challenges to designer due to occurrence of various kinds of instabilities such as excursive instability, density wave oscillations, flow pattern transition instability, geysering and metastable states in parallel channels. This problem assumes greater significance particularly at low-pressures i.e. during startup, where there is great difference in the properties of two phases. In light of this, a parallel channel loop has been designed and installed that has a geometrical resemblance to the pressure-tube-type boiling-water-reactor, to investigate into the behavior of boiling natural circulation. The loop comprises of four identical parallel channels connected between two common plenums i.e. steam drum and header. The recirculation path is provided by a single downcomer connected between steam drum and header. Experiments have been conducted over a wide range of power and pressures (1–10 bar). Two distinct unstable zones are observed with respect to power i.e. corresponding to low power (Type-I) and high power (Type-II) with a stable zone at intermediate powers. The nature of oscillations in terms of their amplitude and frequency and their evolution for Type-I and Type-II instabilities are studied with respect to the effect of heater power and pressure. This paper discusses the evolution of unstable and stable behavior along with the nature of flow oscillation in the channels and the effect of pressure on it.