Synthesis of NaP zeolite at room temperature and short crystallization time by sonochemical method

NaP zeolite nano crystals were synthesized by sonochemical method at room temperature with crystallization time of 3 h. For comparison, to insure the effect of sonochemical method, the hydrothermal method at conventional synthesis condition, with same initial sol composition was studied. NaP zeolites are directly formed by ultrasonic treatment without the application of autogenous pressure and also hydrothermal treatment. The effect of ultrasonic energy and irradiation time showed that with increasing sonication energy, the crystallinity of the powders decreased but phase purity remain unchanged. The synthesized powders were characterized by XRD, IR, DTA TGA, FESEM, and TEM analysis. FESEM images revealed that 50 nm zeolite crystals were formed at room temperature by using sonochemical method. However, agglomerated particles having cactus/cabbage like structure was obtained by sonochemical method followed by hydrothermal treatment. In sonochemical process, formation of cavitation and the collapsing of bubbles produced huge energy which is sufficient for crystallization of zeolite compared to that supplied by hydrothermal process for conventional synthesis. With increasing irradiation energy and time, the crystallinity of the synthesized zeolite samples increased slightly.     

Microwave‐Assisted Copper‐Catalyzed Oxidative Cyclization of Acrylamides with Non‐Activated Ketones

An operationally simple and efficient microwave‐assisted protocol for the oxidative cyclization of acrylamide derivatives with non‐activated ketones to generate 3,3‐disubstituted oxindoles is described. The reaction proceeds by a copper‐catalyzed tandem radical addition/cyclization strategy and tolerates a series of functional groups with moderate to excellent yields.     

Molecular fine structure and transition dipole moment of NO2 using an external cavity quantum cascade laser

Rotational vibrational fine structure and transition dipole moment of NO₂ is measured using Doppler free saturation spectroscopy with an external grating cavity quantum cascade laser (QCL). The QCL wavelength is calibrated using a 310 cm long internally coupled Fabry–Perot interferometer. We obtain a frequency splitting of 139.68 ± 0.06 MHz (0.0047 cm⁻¹) between the spin doublets (17) of 000 → 001 transition of NO₂. The resolution of the QCL based saturation spectrometer is limited by the QCL linewidth of 3.99 MHz ( 0.00013 cm⁻¹) deduced from the half width of the Lamb dips. The Lamb dip spectroscopy is utilized to obtain a vibrational dipole moment of 0.37 Debye for the (17) transitions.     

Effects of periodic masker interruption on the intelligibility of interrupted speech

When listeners hear a target signal in the presence of competing sounds, they are quite good at extracting information at instances when the local signal-to-noise ratio of the target is most favorable. Previous research suggests that listeners can easily understand a periodically interrupted target when it is interleaved with noise. It is not clear if this ability extends to the case where an interrupted target is alternated with a speech masker rather than noise. This study examined speech intelligibility in the presence of noise or speech maskers, which were either continuous or interrupted at one of six rates between 4 and 128 Hz. Results indicated that with noise maskers, listeners performed significantly better with interrupted, rather than continuous maskers. With speech maskers, however, performance was better in continuous, rather than interrupted masker conditions. Presumably the listeners used continuity as a cue to distinguish the continuous masker from the interrupted target. Intelligibility in the interrupted masker condition was improved by introducing a pitch difference between the target and speech masker. These results highlight the role that target-masker differences in continuity and pitch play in the segregation of competing speech signals.     

Synthesis and biological activity of N-substituted-3-chloro-2-azetidinones

2-Aminobenzothiazole-6-carboxylic acid (1), on condensation with chloroacetyl chloride yielded 2-(2-chloroacetylamino)benzothiazole-6-carboxylic acid (2), which on amination with hydrazine hydrate yielded in turn 2-(2-hydrazinoacetylamino)benzo-thiazole-6-carboxylic acid (3). Compound 3, on condensation with various aromatic aldehydes afforded a series of 2-{2-[N'-(arylidene)hydrazino]acetylamino}benzothiazole-6-carboxylic acids 4a-h, which upon dehydrative annulation in the presence of chloroacetyl chloride and triethylamine yielded 2-{2-[3-chloro-2-(aryl)-4-oxoazetidin-1-ylamino]-acetylamino}benzothiazole-6-carboxylic acids 5a-h. The synthesized compounds 4a-h and 5a-h were screened for their antibacterial activity against four microorganisms: Staphylococcus aureus (Gram positive), Bacillus subtilis (Gram positive), Psuedomonas aeruginosa (Gram negative) and Escherichia coli (Gram negative). They were found to exhibit good to moderate antibacterial activity. The antifungal activity of these compounds were also tested against three different fungal species. None of them were active against the species tested.     

HPTLC Densitometric Quantification of Hydrolyzable Tannins from Triphala churna

JPC – Journal of Planar Chromatography – Modern TLC - A simple high-performance thin-layer chromatographic (HPTLC) method has been established for simultaneous quantification of...     

Synthesis of Novel Aryloxy Propanoyl Thiadiazoles as Potential Antihypertensive Agents

2‐Amino‐5‐aryl/alkyl‐1,3,4‐thiadiazoles 3a‐e were synthesized from aliphatic and aromatic acids and thiosemicarbazide. These 2‐amino‐5‐aryl/alkyl‐1,3,4‐thiadiazoles 3a‐e were condensed with 2‐(naphthalenyloxymethyl) oxirane 4a‐b to prepare some naphthalenyloxy‐propanol amine derivatives 5a‐j . These compounds were synthesized as potential antihypertensive agents.     

Evaluating hydrogen-bond propensity,hydrogen-bond coordination and hydrogen-bond energy as tools for predicting the outcome of attempted co-crystallisations

ABSTRACT

Two different structure-informatics based methods and one approach based on hydrogen-bond interaction energies were evaluated for their abilities to predict the experimental outcomes of attempted co-crystallisations between two known drug molecules, Nevirapine and Diclofenac, and a series of potential co-formers. The hydrogen-bond propensity (HBP) tool gave the correct result in 26 out of 30 cases, whereas a hydrogen-bond coordination (HBC) method predicted the correct outcome in 22 out of 30 cases. Finally, calculated hydrogen-bond energies (HBE) using a simple electrostatic model, gave the correct result in 23 out of 30 experiments. In those cases, where the crystal structure of a co-crystal of either Nevirapine or Diclofenac was known, we also examined how well the three methods predicted which primary hydrogen-bond interactions were present in the crystal structure. HBP correctly predicted 6 out of 6 cases, HBC could not predict any of the synthon formations correctly, and HBE successfully predicted 1 out of 6 cases.     

Oxidation of benzyl alcohol by Cr<Superscript>VI</Superscript> supported on Ambersep 900 (O<Superscript>−</Superscript>H) – a kinetic and mechanistic investigation

The oxidation of benzyl alcohol was found to proceed through ester formation. In a slow step the ester decomposes and produces chromium(IV). Chromium(IV) formed in a slow step, oxidizes another molecule of benzyl alcohol because our oxidant was supported on polymeric material and generates a free radical in a fast step. The free radical subsequently reacts with another oxidant site in a polymeric reagent in a fast step and forms chromium(V). In a last step the intermediate chromium(V) reacts with benzyl alcohol to produce benzaldehyde. The mechanism was predicted and activation parameters were also determined.     

Stearate as a green corrosion inhibitor of magnesium alloy ZE41 in sulfate medium

The efficiency of stearate as a corrosion inhibitor for magnesium alloy ZE41 has been studied in sodium sulfate medium, employing electrochemical techniques like potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results of polarization study imply that stearate functions as a mixed-type corrosion inhibitor with a predominant anodic control. The adsorption of stearate on alloy surface is found to obey the Langmuir adsorption isotherm. The proposed inhibition mechanism involved adsorption of stearate onto metal surface, followed by precipitation of magnesium stearate within the microdefects of Mg(OH)₂ surface film which enhanced the barrier effect of an otherwise porous partially protective film.