Surface modification via wet chemical etching of single-crystalline silicon for photovoltaic application

The potential of solar cells have not been fully tapped due to the lack of energy conversion efficiency. There are three important mechanisms in producing high efficiency cells to harvest solar energy; reduction of light reflectance, enhancement of light trapping in the cell and increment of light absorption. The current work represent studies conducted in surface modification of single-crystalline silicon solar cells using wet chemical etching techniques. Two etching types are applied; alkaline etching (KOH:IPA:DI) and acidic etching (HF:HNO₃:DI). The alkaline solution resulted in anisotropic profile that leads to the formation of inverted pyramids. While acidic solution formed circular craters along the front surface of silicon wafer. This surface modification will leads to the reduction of light reflectance via texturizing the surface and thereby increases the short circuit current and conversion rate of the solar cells.     

Microwave assisted alkali-catalyzed transesterification of Pongamia pinnata seed oil for biodiesel production

In this study, microwave assisted transesterification of Pongamia pinnata seed oil was carried out for the production of biodiesel. The experiments were carried out using methanol and two alkali catalysts i.e., sodium hydroxide (NaOH) and potassium hydroxide (KOH). The experiments were carried out at 6:1 alcohol/oil molar ratio and 60 °C reaction temperature. The effect of catalyst concentration and reaction time on the yield and quality of biodiesel was studied. The result of the study suggested that 0.5% sodium hydroxide and 1.0% potassium hydroxide catalyst concentration were optimum for biodiesel production from P. pinnata oil under microwave heating. There was a significant reduction in reaction time for microwave induced transesterification as compared to conventional heating.     

Biofiltration of isopropyl alcohol by a trickle-bed air biofilter

The performance of trickle-bed air biofilter (TBAB) for the removal of isopropyl alcohol (IPA) was evaluated in concentrations varying from 100 to 500 ppmv and at empty-bed residence time (EBRT) varying from 20 to 90 s. Nearly complete IPA removal could be achieved for influent carbon loading between 6 and 88 g/m^3·h. The TBAB appears efficient for controlling IPA emission under low-to-high carbon loading conditions. Carbon recoveries of 95-99% were achieved demonstrating the accuracy of results. Applicable operating conditions of TBAB for controlling IPA emission were suggested.     

Isopropanol biodegradation by immobilized Paracoccus denitrificans in a three-phase fluidized bed reactor

A three-phase bed bioreactor including a mix of immobilized microbes was used to degrade isopropanol (IPA). The immobilization method was studied and cells immobilized with calcium alginate, polyvinyl alcohol, activated carbon, and SiO₂ were demonstrated to be the best immobilization method for the degradation of 90% of 2?g/L IPA in just 4 days, 1 day earlier than with free cells. Acetone was monitored as an indicator of microbial IPA utilization as the major intermediate of aerobic IPA biodegradation. The bioreactor was operated at hydraulic retention time (HRT) values of 32, 24, 16, 12, and 10?hr, which correspond to membrane fluxes of 0.03, 0.04, 0.06, 0.08, and 0.10?L/m²/hr, respectively. The chemical oxygen demand (COD) removal efficiencies were maintained at 98.0, 97.8, 89.1, 80.6, and 71.1% at a HRT of 32, 24, 16, 12, and 10?hr, respectively, while the IPA degradations were 98.6, 98.3, 90.3, 81.6, and 73.3%, respectively. With a comprehensive consideration of COD removal and economy, the optimal HRT was 24?hr. The results demonstrate the potential of immobilized mixed bacterial consortium in a three-phase fluidized bed reactor system for the aerobic treatment of wastewater containing IPA.     

Use of Mycological, nested PCR, and Real-time PCR Methods on BAL Fluids for Detection of Aspergillus fumigatus and A. flavus in Solid Organ Transplant Recipients

Invasive aspergillosis continues to be a significant cause of morbidity and mortality in solid organ transplant (SOT) recipients. A reliable and early diagnostic method is needed to improve survival. In this study, four methods direct microscopy, culture, nested PCR on internal transcribed spacer region, and TaqMan real-time PCR targeted β-tubulin gene were examined for the detection of Aspergillus fumigatus and A. flavus in sixty-four bronchoalveolar lavage (BAL) fluids that were obtained from SOT recipients. Direct examination with 20 % KOH (potassium hydroxide) and culture on mycological media were also performed. Of the 64 samples, seven (10.9 %) were positive in direct examination (five with septate hyphae and two with aseptate hyphae), and 15 (23 %) had positive culture including five A. flavus, four A. niger, two Penicillium spp., two Rhizopus spp., one Fusarium spp. and one mixed A. flavus/A. niger. Twenty five (39 %) samples had positive nested PCR with A. flavus and 6 (9.4 %) with A. fumigatus-specific primers. Only eight (12.5 %) had positive real-time PCR for A. flavus and nine (14 %) for A. fumigatus. The incidence of aspergillosis in these patients included proven invasive pulmonary aspergillosis (IPA) in two (3 %), probable IPA in 14 (22 %), possible IPA in 38 (59 %), and not IPA in 10 (16 %). A. flavus was the most common cause of pulmonary aspergillosis (PA) in the study. The results suggest that because nested PCR is too sensitive it may increase the number of false-positive results and is not recommended for BAL samples for diagnosis of PA. Although further studies with significant number of proved positive/negative standard BAL samples are necessary for better evaluation, the novel multiplex real-time PCR developed in the study could be promising as a valid diagnostic method for IPA.     

Harmful algal blooms mitigation using clay/soil/sand modified with xanthan and calcium hydroxide

A method was studied for marine harmful algal blooms (HABs) mitigation using clay, soil, or sand modified with xanthan and calcium hydroxide. Results showed that xanthan could trap and wrap Amphidinium carterae cells via bridging and netting interactions due to its superior salt compatibility in seawater. The maximum cell removal efficiency was 55% when xanthan was used alone. The removal effect of xanthan was enhanced by the addition of appropriate calcium hydroxide that decreased the repulsive interaction between anionic xanthan and negatively charged algal cells. Three kinds of minerals (clays, soils, and sands) were ineffective in removing algal cells before treatment. When xanthan and calcium hydroxide were used together as modifiers, the removal efficiency increased to 83–89% within 30?min using 300?mg?L^?1 clays, soils, or sands modified with 20?mg?L^?1 xanthan and 100?mg?L^?1 calcium hydroxide. After several hours, 95–98% cell removal was achieved and there was no significant difference in the removal efficiencies among clays, soils, and sands after being modified with xanthan and calcium hydroxide. Thus, the method would provide an alternative modification approach to suppress and mitigate HABs using local soils/sands and polymers in marine systems.     

Action comparée de la 6-furfurylaminopurine et de la 6-(γ, γ-dimethylallylainino)purine sur la croissance, l'activité peroxydasique, la teneur en chlorophylles et en caroténoïdes

Comparative Effects of 6-Furfurylaminopurine and 6-(γ, γ-Dimethylallylamino) purine on Growth, Peroxidase, Chlorophyll and Carotenoid Content. — 6-Furfurylaminopurine (FAP) and 6-(γ, γ-dimethylallylamino) purine (IPA) both inhibit root growth and cause an increase in peroxidase activity. When used at 10^?8 and 10^?8M, IPA stimulates elongation of the coleoptile test, at 10^?4M both FAP and IPA provoke an inhibition. FAP and IPA maintain a high level in chlorophylls and carotenoids in floating leaves discs. In all these experiments, IPA has thus a higher effect than FAP.     

Liquid scintillation counting of aqueous solutions of potassium salts in a Triton X-100/toluene scintillant

The use of a toluene/Triton X-100 scintillant for counting ¹⁴C in aqueous solutions of potassium salts including potassium hydroxide has been investigated. Suitable conditions for the counting of CO₂ entrapped in potassium hydroxide are described. Quench correction by automatic external standard channels ratio procedures has been found to be of value with optimised conditions of counting.     

Control by calcium of protein discharge and membrane permeability to potassium in the rat lacrimal gland

Discharge of protein from slices of rat exorbital lacrimal gland was stimulated by 10^?5 M carbachol. This response was blocked by 10^?4 M atropine or by the omission of extracellular calcium. In the latter case, secretion could be restored by the reintroduction of calcium to the medium. Carbachol (10^?5 M) also stimulated the release of ⁸⁶Rb (a marker for potassium) from the slices. This effect was completely blocked by 10^?4 M atropine. The initial transient release of ⁸⁶Rb was only partially inhibited by Ca removal, but the later sustained phase of release was completely blocked. As with protein secretion, this effect of Ca removal could be reversed by re-introduction of Ca to the medium. It is concluded that activation of cholinergic receptors in the lacrimal gland stimulates protein discharge and increases potassium permeability by mechanisms utilizing extracellular calcium ions.     

Efficacy of the Ryu nonstaining KOH technique for rapidly determining gram reactions of food-borne and waterborne bacteria and yeasts.

A simple and rapid (< 60 s) nonstaining technique with 3% potassium hydroxide to determine Gram reactions was tested with 495 food-borne and waterborne bacteria and yeasts. In KOH, suspensions of gram-negative bacteria become viscous and string out. Gram-positive bacteria are not affected. There was 100% correlation between the KOH string test results and gram-positive and gram-negative strains.     

Elasto-Capillary Folding Using Stop-Programmable Hinges Fabricated by 3D Micro-Machining

We show elasto-capillary folding of silicon nitride objects with accurate folding angles between flaps of (70.6 ± 0.1)° and demonstrate the feasibility of such accurate micro-assembly with a final folding angle of 90°. The folding angle is defined by stop-programmable hinges that are fabricated starting from silicon molds employing accurate three-dimensional corner lithography. This nano-patterning method exploits the conformal deposition and the subsequent timed isotropic etching of a thin film in a 3D shaped silicon template. The technique leaves a residue of the thin film in sharp concave corners which can be used as an inversion mask in subsequent steps. Hinges designed to stop the folding at 70.6° were fabricated batchwise by machining the V-grooves obtained by KOH etching in (110) silicon wafers; 90° stop-programmable hinges were obtained starting from silicon molds obtained by dry etching on (100) wafers. The presented technique has potential to achieve any folding angle and opens a new route towards creating structures with increased complexity, which will ultimately lead to a novel method for device fabrication.     

Composition of cell wall preparations of rice bran and germ

Cell walls of petrol-defatted non-waxy IR32 rice bran and germ were prepared by protein removal with 0.5% SDS—0.6% β-mercaptoethanol, heating the residue to 80°, and destarching with Bacillus licheniformis α-amylase. A waxy rice, IR29, had a similar cell wall composition as IR32. Principal wall sugars were arabinose, xylose, and glucose. The 0.5 M sodium or potassium hydroxide and 8 M urea preferentially extracted arabinose-, xylose- and uronic acid-rich polysaccharides but 6 M sodium hydroxide—0.81 M boric acid extracted mannose-rich polysaccharides. DEAE-cellulose BO₃^3? chromatography of the 0.5 M sodium hydroxide extracts gave fractions of similar arabinose— xylose ratios. Proteins in the cell wall preparations had only 0.4–1.6% hydroxyproline, and were bound mainly to polysaccharides, based on disc gel electrophoresis. The preparations were autofluorescent in UV and rich in phenols, mainly ferulic acid. The cell wall preparations and their 8 M urea fractions had a softening effect on defatted waxy starch aqueous gel at 0.2–2% of the starch.     

Biodegradation of Isopropanol by a Solvent-Tolerant Paracoccus denitrificans Strain

The biodegradation of high concentration isopropanol (2-propanol, IPA) at 16 g/L was investigated by a solvent-tolerant strain of bacteria identified as Paracoccus denitrificans for the first time by 16S rDNA gene sequencing. The strain P. denitrificans GH3 was able to utilize the high concentration of IPA as the sole carbon source within a minimal salts medium with a cell density of 1.5 × 10⁸ cells/mL. The optimal conditions were found as follows: initial pH 7.0, incubation temperature 30°C, with IPA concentration 8 g/L. Under the optimal conditions, strain GH3 utilized 90.3% of IPA in 7 days. Acetone, the major intermediate of aerobic IPA biodegradation, was also monitored as an indicator of microbial IPA utilization. Both IPA and acetone were completely removed from the medium following 216 hr and 240 hr, respectively. The growth of strain GH3 on IPA as a sole carbon and energy source was well described by the Andrews model with a maximum growth rate (μ _max ) = 0.0277/hr, a saturation constant (K _S ) = 0.7333 g/L, and an inhibition concentration (Ki) = 8.9887 g/L. Paracoccus denitrificans GH3 is considered to be well used in degrading IPA in wastewater.     

An enzyme-linked immunosorbent assay to detect alkali-soluble spore surface antigens of strains of Nosema bombycis (Microspora: Nosematidae)

Spore surface antigens of strains of Nosema bombycis were extracted with alkaline solutions and used in an indirect enzyme-linked immunosorbent assay. Treatment of N. bombycis spores with 0.1 n potassium carbonate or potassium hydroxide solution at 27°C for 30 min was sufficient for the extraction of the antigens. Usually, 10⁸ spores of N. bombycis liberated ca. 30 μg spore surface proteins. The indirect enzyme-linked immunosorbent assay detected as little as 60 ng of spore surface proteins (ca. 2000 spore-equivalent antigen). The alkali-soluble spore surface antigens of N. bombycis contained a specific antigen and were stable under storage at −20°C for more than 1 year. The serological assay separated the Nosema isolates pathogenic to the silkworm into three groups.     

Effect of exogenous acetylcholine on potassium currents in the frog motor nerve ending during acetylcholinesterase inhibition

The effect of exogenous acetylcholine (ACh) on potassium currents in the motor nerve ending (NE) has been studied in neuromuscular preparations of the frog cutaneous-sternal muscle by extracellular recording of evoked electrical potentials from the NE. The investigation was performed during inhibition of acetylcholinesterase (AChE) activity by specific inhibitors and AChE removal from the synaptic cleft by collagenase. After AChE inhibition by either armine or proserine, or after treatment of the preparation with collagenase, no effect of exogenous ACh in concentrations of 1·10^–4–6·^–4 mole/liter was observed, in contrast to results from preparations with intact AChE. However, under the same conditions, as in the case of active AChE, ACh in concentrations of 7·10^–4–2·10^–3 mole/liter inhibited Ca-activated potassium current of the NE membrane. Experiments with dipyroxim, a synaptic AChE reactivator, have shown that the ACh effect on the potential-dependent potassium current is mediated by specific AChE. The role of AChE is discussed in respect to its significance for realization of the ACh action on potential-dependent potassium current in NE.Translated from Neirofiziologiya, Vol. 25, No. 2, pp. 146–149, March–April, 1993.     

Pollen size in Carex: The effect of different chemical treatments and mounting media

Pollen size and pollen aperture size for ten species of the genus Carex L., native to Estonia, have been measured using light microscopy. The species selected represent different sections of the genus, a range of habitats and different chromosome numbers. The effects of two basic chemical treatments, two mounting media and the effect of chemically induced dehydration with tertiary butyl alcohol (TBA) on the size of pollen grains were then recorded.

In general pollen size and pollen aperture size of the species examined is highly variable at both intraspecific and interspecific levels. Carex hirta has notably larger pollen grains than any of the other species investigated and, although correlations between size and chromosome number in the species examined are limited, it also has the highest chromosome number. Statistically significant size differences resulted from variations in chemical treatment, mounting media and tertiary butyl alcohol (TBA) induced dehydration. Acetolysed pollen grains are larger than potassium hydroxide (KOH) treated pollen grains. Pollen grains dehydrated after chemical treatment with TBA are larger than pollen grains not dehydrated. Pollen grains mounted in silicon oil are smaller than grains mounted in glycerine. But considering the great size variation of Carex pollen grains, the size changes caused by preparation procedures fall within the size variation range of the species examined.

All the samples contained a high number of deformed pollen grains and pollen grains with hardly distinguishable or no lateral apertures.     

Physiology and ecologic relevance of salt secretion by the salt gland of Glaux maritima L.

Summary The effects of salinity in the root medium, time, and relative humidity on the salt secretion of Glaux maritima were investigated. Both in the greenhouse and in the field increasing salinity stimulated sodium and chloride secretion, whereas the essential elements potassium, calcium, and magnesium remained at low secretion levels, which might be interpreted as efficient mineral economy. The low secretion level of potassium is remarkable, because growing on a nutrient solution containing 6 mM potassium, the concentration of the plant sap increases to 150 mM K⁺ and the secreted quantity amounts to only 2 m mol l^-1 plant sap 24 h^-1.Attempts were made to establish the secretion rate. The maximum secretion rate calculated may be 80 pEq NaCl cm^-2 s^-1, but for long periods (days) the secretion rate will be lower. Measurement of salt secretion unavoidably leads to removal of secreted salt. Salt was removed by rinsing with distilled water, which artificially accelerates the secretion process or parts of it by diffusion of salt from the cuticle cavity or secretory cells. At increasing salinities the amount of secreted ions showed a fivefold increase, whereas the osmotic potential of the plant sap was raised only twofold, indicating the importance of secretion as a rapid regulation mechanism with regard to the salt economy.     

Two-step biodiesel production from Calophyllum inophyllum oil: Optimization of modified β-zeolite catalyzed pre-treatment

In this study, a two-step process was developed to produce biodiesel from Calophyllum inophyllum oil. Pre-treatment with phosphoric acid modified β-zeolite in acid catalyzed esterification process preceded by transesterification which was done using conventional alkali catalyst potassium hydroxide (KOH). The objective of this study is to investigate the relationship between the reaction temperatures, reaction time and methanol to oil molar ratio in the pre-treatment step. Central Composite Design (CCD) and Response Surface Methodology (RSM) were utilized to determine the best operating condition for the pre-treatment step. Biodiesel produced by this process was tested for its fuel properties.     

Modifying and Fine Controlling of Silver Nanoparticle Nucleation Sites and SERS Performance by Double Silicon Etching Process

Different forms of modified and well-controlled plasmonic silver nanoparticles (AgNPs) were synthesized by silver ion reduction process of porous silicon (PS). Fine control of PS surface morphology was accomplished by employing two etching processes: light-induced etching (LIE) and photo electrochemical etching (PECE). The idea was to prepare excellent and reproducible surface-enhanced Raman scattering (SERS) substrates with high enhancement performance. PS surface modification was employed to create efficient and nearly uniformly distributed AgNP hotspot regions with very high specific surface areas. Reproducibility deviation of no more than 5% and enhancement factor of 1.2 × 10¹⁴ were obtained by SERS measurements at very low, rhodamine 6G (R6G) dye, concentration 10^?15 M. The PS morphology SERS substrate was well discussed and analyzed using field emission scanning electron microscopy (FE-SEM), X-ray diffraction spectroscopy (XRD), and Raman measurements.     

Profile of Dermatophytic and Other Fungal Infections in Jaipur

The common cause of skin infections are dermatophytes and opportunistic fungi. Aim of present study is to find predominant etiological agent of dermatophytoses and to isolate various fungal agents from clinical samples of patients with different mycoses and Clinical samples from 260 patients were subjected to potassium hydroxide (KOH) examination and culture isolation; causative agents were identified macroscopically and microscopically. One hundred sixty three (62.7%) were found to be positive by KOH examination while 132 (50.8%) were culture positive. Dermatophytes were isolated in 90/140 (64.3%) specimens. Trichophyton rubrum (75.5%) was the commonest isolate among the patients suffering from dermatophytoses. Candida spp. and Malassezia furfur were isolated from patient suffering from candidiasis and pityriasis versicolor.