Phytol Derivatives as Drug Resistance Reversal Agents

Phytol was chemically transformed into fifteen semi‐synthetic derivatives, which were evaluated for their antibacterial and drug resistance reversal potential in combination with nalidixic acid against E. coli strains CA8000 and DH5α. The pivaloyl ( 4 ), 3,4,5‐trimethoxybenzoyl ( 9 ), 2,3‐dichlorobenzoyl ( 10 ), cinnamoyl ( 11 ), and aldehyde ( 14 ) derivatives of phytol ((2E,7R,11R)‐3,7,11,15‐tetramethyl‐2‐hexadecen‐1‐ol) were evaluated by using another antibiotic, tetracycline, against the MDREC‐KG4 clinical isolate of E. coli. Derivative 4 decreased the maximal inhibitory concentration (MIC) of the antibiotics by 16‐fold, while derivatives 9 , 10 , 11 , and 14 reduced MIC values of the antibiotics up to eightfold against the E. coli strains. Derivatives 4 , 9 , 10 , 11 , and 14 inhibited the ATP‐dependent efflux pump; this was also supported by their in silico binding affinity and down‐regulation of the efflux pump gene yojI, which encodes the multidrug ATP‐binding cassette transporter protein. This study supports the possible use of phytol derivatives in the development of cost‐effective antibacterial combinations.     

Synthesis of nano-structured 3C-SiC by carbothermal reduction of silicon bearing gel and carbon soot

Nano-sized 3C-SiC was synthesized using sol-gel method. The silica bearing sol was prepared using fumed silica and alkaline ethylene glycol which on hydrolysis resulted in a gel. The gel was mixed with nano-sized carbon particles (obtained from soot) and heat treated in 1300-1580 °C temperature range. The formation of 3C-SiC began at ~ 1400 °C and at 1580 °C it was observed to be the major phase while small amount of 2H-SiC was also present. The silicon carbide synthesized between 1400 and 1580 °C had particles in 30-50 nm range and crystallite size between 15 and 17 nm.     

Synthetic musk emissions from wastewater aeration basins

Wastewater aeration basins at publicly owned treatment works (POTWs) can be emission sources for gaseous or aerosolized sewage material. In the present study, particle and gas phase emissions of synthetic musks from covered and uncovered aeration basins were measured. Galaxolide (HHCB), tonalide (AHTN), and celestolide (ADBI) were the most abundant, ranging from 6704 to 344,306 ng m⁻³, 45-3816 ng m⁻³, and 2-148 ng m⁻³ in the gas phase with particle phase concentrations 3 orders of magnitude lower. The musk species were not significantly removed from the exhaust air by an odor control system, yielding substantial daily emission fluxes (∼200 g d⁻¹ for HHCB) into the atmosphere. However, simple dispersion modeling showed that the treatment plants are unlikely to be a major contributor to ambient air concentrations of these species. Emission of synthetic musk species during wastewater treatment is a substantial fate process; more than 14% of the influent HHCB is emitted to the atmosphere in a POTW as opposed to the <1% predicted by an octanol-water partition coefficient and fugacity-based US EPA fate model. The substantial atmospheric emission of these compounds is most likely due to active stripping that occurs in the aeration basins by bubbling air through the sludge.     

Estimation of average life for negative exponential distribution

This paper deals with the problem of average life estimation when the life times follow negative exponential distribution. A minimum mean square error estimator belonging to the class of linear combination of complete sufficient statistics has been obtained. The estimator thus obtained requires knowledge of coefficient of variation. The effect of using a guessed value of coefficient of variation on the estimator has also been studied.     

Assessment of carbonic anhydrase activity in blood by alteration in pH

Carbonic anhydrase enzyme activity could be measured by manometeric and colorimetric techniques. A simpler and modified method of carbonic anhydrase enzyme activity assessment in blood is proposed. In the present method differences in pH by hydration of CO2 in absence and presence of carbonic anhydrase inhibitor have been used to measure the carbonic anhydrase activity in the blood.     

Bayes results for classical Pareto distribution via Gibbs sampler,with doubly-censored observations

The paper considers the full Bayes analysis of the Pareto distribution when the observations are doubly censored, and provides sample-based estimates of posterior distributions using Gibbs sampler algorithm. The approach is not only computationally simple but fully explores the low-dimensional posterior surfaces-which otherwise seems difficult. Complexities through censored data always arise in life testing experiments; these complexities are no longer problems with the Gibbs sampler algorithm, unlike the situations with nonsample-based approaches     

Interplay of low and highT c phases in Bi-Sr-Ca-Cu-O superconductor

In the Bi-Sr-Ca-Cu-O system stringent conditions of heat-treatment lead to the formation of a mixture of both the low and highT _c phases and obtaining a single-phase material becomes extremely difficult. This study reports preparation of samples with single superconducting transitions at ∼ 75 K and ∼ 108 K; the compositions of which correspond ton=2,3 in the series Bi₂Sr₂Ca _n−1Cu _n O_{4 + 2n} . X-ray diffraction studies show that the lowerT _c material is a relatively pure phase while the higherT _c phase only co-exists with the lowerT _c phase. The most obvious effect of doping the system with lead is to make the reaction take place faster and thereby increase the volume fraction of the 110K phase.     

Gonadal preservation in a simple testicular cyst

The authors report a case of a simple testicular cyst in a 16-week-old infant. Preoperative ultrasonography helped to diagnose this condition accurately. Gonadal preservation and enucleation of testicular cysts are possible with a careful surgical approach, and orchiectomy is not necessary.     

Analysis and design of a half-bridge parallel resonant converter

A half-bridge parallel resonant converter (PRC) is analyzed in detail for both continuous-conduction-mode and discontinuous-conduction-mode operations to provide more straightforward and easy-to-use design tools. Closed-form solutions are derived for the PRC operating under steady-state conditions. Theoretical results obtained are presented in the form of normalized design graphs. They could be directly utilized in designing a half-bridge PRC, having up to 2:1 input voltage variation. They do not necessitate converting the obtained ratings, depending on the input voltage and load variations, to check the worst case values. A design example of a 500 kHz 150 W offline switching power supply is given for both modes of operation, and it is implemented for experimental verification.<>