Importance of conduction electron correlation in a Kondo lattice, Ce₂CoSi₃

Kondo systems are usually described by the interaction of the correlation induced local moments with the highly itinerant conduction electrons. Here, we study the role of electron correlations among conduction electrons in the electronic structure of a Kondo lattice compound, Ce₂CoSi₃, using high resolution photoemission spectroscopy and ab initio band structure calculations, where Co 3d electrons contribute in the conduction band. High energy resolution employed in the measurements helped to reveal the signatures of Ce 4f states derived Kondo resonance features at the Fermi level and the dominance of Co 3d contributions at higher binding energies in the conduction band. The lineshape of the experimental Co 3d band is found to be significantly different from that obtained from the band structure calculations within the local density approximations, LDA. Consideration of electron-electron Coulomb repulsion, U, among Co 3d electrons within the LDA + U method leads to a better representation of experimental results. The signature of an electron correlation induced satellite feature is also observed in the Co 2p core level spectrum. These results clearly demonstrate the importance of the electron correlation among conduction electrons in deriving the microscopic description of such Kondo systems.

Extensive variation and heteroplasmy in size of mitochondrial DNA among geographic populations of Drosophila melanogaster

Size variation and heteroplasmy in mitochondrial DNA (mtDNA) are relatively common in natural populations of Drosophila melanogaster. Of 92 isofemale lines of flies obtained from various geographic regions throughout the world, 75 lines were homoplasmic and showed a total of 12 different mtDNA size classes. The remaining 17 lines were heteroplasmic, each line carrying two different mtDNAs, and, in all but one case, the mtDNAs in these heteroplasmic lines differed in size; a total of nine size classes was represented among them. In cases where one type was predominant within an individual, it was usually the smaller mtDNA. This finding parallels what was observed in homoplasmic lines, in that the smaller mtDNAs were much more common than the larger variants in most populations. The data suggest a high rate of mutational occurrence of mtDNA size variants and some natural selection against them.

Biofiltration of toluene using wood charcoal as the biofilter media

A laboratory scale biofilter inoculated with Pseudomonas putida (MTCC 102) was used for degradation of toluene present in air. Wood charcoal was used as the filter media and a layer of glass beads (6mm) was used for improved air distribution. The biofilter was operated continuously for a period of 5months at four different flow rates - 0.06, 0.12, 0.18, and 0.24m(3)h(-1), with inlet concentration of toluene ranging from 0.04 to 4.5gm(-3). Air having toluene vapor was fed to the biofilter at various loadings ranging from 30.6 to 1104.5gm(-3)h(-1). The removal efficiency was obtained in the range of 70-99.5%. The maximum elimination capacity of 872.5gm(-3)h(-1) was observed at the inlet load of 1104.5gm(-3)h(-1). Wood charcoal was found to an effective biofilter media for toluene biodegradation.

Bio-filtration of trichloroethylene using diazotrophic bacterial community

Biodegradation of TCE was studied in a biofilter packed with wood charcoal and inoculated with diazotrophic bacterial community isolated from local soil. Steady state TCE removal efficiencies higher than 85% were observed up to inlet load of 2.866 g m(-3) h(-1). The maximum elimination capacity of 5.31 g m(-3) h(-1) was observed at an inlet load of more than 7.90 g m(-3) h(-1). The biofilter was sensitive to fluctuations in the process conditions but could easily recover its performance after 10 days shutdown. Almost constant and small pressure drop per unit length and very negligible compaction was observed during the whole experimental period. The molecular analyses such as RT-PCR and gene sequencing revealed the presence of functionally active Azospirillum species in the biofilm.

Ayurvedic processed seeds of nux-vomica: neuropharmacological and chemical evaluation

The effect of detoxification on Strychnos nux-vomica seeds by traditional processing with aloe and ginger juices (B), by frying in cow ghee (C), and by boiling in cow milk (D) was investigated. The ethanolic extracts of these samples were subjected to spontaneous motor activity (SMA), pentobarbitone-induced hypnosis, PTZ induced convulsions, diazepam-assisted protection, and morphine-induced catalepsy. All samples reduced SMA and inhibited catalepsy. The seeds processed in milk (D) showed the lowest strychnine content in the cotyledons, exhibited marked inhibition of PTZ induced convulsions and maximal potentiation of hypnosis, and were the safest (LD(50)).

Toward a 1550 nm InGaAs photoconductive switch for terahertz generation

We report a terahertz (THz) photoconductive switch made from a composite of metal ErAs nanoparticles embedded in In(0.53)Ga(0.47)As and coupled to a square spiral antenna. The THz output power was measured in a 77 K cryostat by using a standard hyperhemisphere-lens package, a Golay cell outside the cryostat, and a quasi-optical filter bank for spot frequency spectral measurements. Results indicate an average output power of approximately 12 microW at 22 V bias using 140 mW of optical pump power from a subpicosecond fiber mode-locked laser. In addition, the THz spectra displayed invariance to bias voltage despite operating near impact ionization.

Biosorption studies of nickel on Parthenium hysterophorous ash

The application of an aquatic weed, Parthenium hysterophorous, has been investigated for the removal of nickel from aqueous solutions. Parthenium hysterophorous, the weed was converted to ash and was used as an adsorbent for the removal of nickel(II) from aqueous solutions at different experimental conditions. The per cent removal of Ni increased from 67.30 to 97.54%, with the nickel(II) concentration decreasing from 477.21 to 67.83 mg L(-1) at 25 degrees C, pH 11.0. The removal was favoured at higher pH, with a maximum removal at pH 11.0. The effects of concentration and temperature are also reported. Batch adsorption kinetics are described by the Lagergren equation. The value of the rate constant of adsorption was found to be 6.82 x 10(-2) min(-1) at 67.83 mg L(-1) and 25 degrees C. The applicability of the Langmuir and Freundlich equations for the present system were tested at different temperatures, viz. 25, 50 and 75 degrees C, and the constants were calculated. Thermodynamic parameters indicate the exothermic nature of nickel(II) adsorption on P. hysterophorous ash. The adsorption capacity was found to be much better than other common adsorbents reported for the removal of nickel(II).

Impact of post-mining subsidence on nitrogen transformation in southern tropical dry deciduous forest, India

The goal of our research was to assess the impact of post-mining land subsidence, caused due to underground coal mining operations, on fine root biomass and root tips count; plant available nutrient status, microbial biomass N (MBN) and N-mineralization rates of a Southern tropical dry deciduous forest of Singareni Coalfields of India. The changes were quantified in all the three (rainy, winter and summer) seasons, in slope and depression microsites of the subsided land and an adjacent undamaged forest microsite. Physico-chemical characteristics were found to be altered after subsidence, showing a positive impact of subsidence on soil moisture, bulk density, water holding capacity, organic carbon content, total N and total P. The increase in all the parameters was found in depression microsites, while in slope microsites, the values were lower. Fine root biomass and root tips count increased in the subsided depression microsites, as demonstrated by increases of 62% and 45%, respectively. Soil nitrate-N and phosphate-P concentrations were also found to be higher in depression microsite, showing an increase of 35.68% and 24.74%, respectively. Depression microsite has also shown the higher MBN value with an increase over control. Net nitrification, net N-mineralization and MBN were increased in depression microsite by 29.77%, 25.72% and 34%, respectively. There was a positive relation of microbial N with organic C, fine root biomass and root tips.

Sarcomatoid squamous cell carcinoma: a long-standing case

Sarcomatoid, or spindle cell squamous cell carcinoma (SCSC), is relatively uncommon, but may be encountered. It poses a challenge in differential diagnosis that includes other spindle cell neoplasms. We present a case where the lesion existed for 20 years and raised the potential of chronicity as a factor in inducing spindle cell morphology. Detailed immunohistochemical features are demonstrated, and discussion of the differential diagnosis is offered. The patient was an 89-year-old African-American female with an exophytic and polypoid mass of the right upper arm measuring 5.5 x 5.5 x 3.0 cm. The mass had been present for the last 20 years, and was gradually and very slowly increasing in size. After refusing surgery several times, she finally agreed to have an excision. The tumor proved to be SCSC.

Production of extracellular exoinulinase from Kluyveromyces marxianus YS-1 using root tubers of Asparagus officinalis

Root tubers of Asparagus officinalis were used as a source of raw inulin for the production of exoinulinase (EC 3.2.1.7) from Kluyveromyces marxianus YS-1. Root extract prepared at 10kg/cm2 pressure for 10min showed maximum inulinase production. Medium components and process parameters were standardized to improve the enzyme production. Inulinase yield of 40.2IU/mL in a medium containing raw inulin (3.5%), beef extract (2%), SDS (0.001%), Mn2+ (2.0mM), Mg2+ (1.5mM), Co2+ (2mM) and pH 6.5 has been obtained under agitation (150rpm) after 60h of incubation at 30 degrees C at shake flask level. After optimization, the enzyme production was 4.8 times more than the basal medium. To test the feasibility of raw inulin from A. officinalis for the production of inulinase, trials were also made in a bioreactor (1.5L). Inulinase activity of 50.2IU/mL was obtained from raw inulin (4.0%) under agitation (200rpm) and aeration (0.75vvm) at 30 degrees C after 60h of fermentation. Inulinase yield in bioreactor was almost six times higher than the basal medium used initially in shake flask.

Angioinvasive pulmonary mucormycosis presenting as multiple bilateral pulmonary nodules in a patient without obvious predisposing factors

Pulmonary mucormycosis is a rare, frequently fatal, fungal infection. It is usually seen in the presence of various immunocompromised states, such as diabetes mellitus, haematological malignancy or renal transplantation. In the absence of underlying predisposing conditions, presentation with infiltrates, consolidation, cavitation and mass lesion have been reported. We describe a 50-year-old man who presented with cough and chest pain for six months. Chest radiograph and computed tomography showed bilateral multiple pulmonary nodules. Surgical lung biopsy revealed angioinvasive mucormycosis. He had complete recovery with amphotericin therapy.

Meningitis and cochlear implantation in Scotland

Meningitis is responsible for a considerable proportion of profoundly deafened children. At the Scottish Cochlear Implant Centre, those attending for cochlear implant assessment with post-meningitic deafness were identified from 1989 to 1999. In those found suitable, findings at surgery were recorded. Meningitis notifications in Scotland from 1988 to 1998 were also studied. Out of 550 patients, 45 were found to have post-meningitic deafness. Of these, 32 were implanted and 12 were rejected. Of those implanted, 10 were affected by cochlear ossification. In five of these patients, a full insertion of a multichannel device was impossible and as a result, auditory rehabilitation was less satisfactory. Meningitis in Scotland appears to have been declining from 1988 to 1998.

Reflective terahertz imaging of porcine skin burns

A reflective pulsed terahertz imaging system based on direct detection was developed and used to obtain high-resolution images of a porcine skin specimen with superficial partial-thickness (second-degree) burns. Images were also obtained of the sample through ten layers of dry medical (cotton) gauze with minimal image degradation. The burned and unburned regions of skin had large differences in terahertz reflectivity, displaying clear delineation [20 dB signal-to-noise ratio (SNR) difference signal] between both regions in the images. The terahertz images also exhibited a "halo" surrounding the burn areas that may correlate to the extent of burn injury. The system operated at a center frequency of 500 GHz with 125 GHz of 3 dB bandwidth and used whiskbroom scanning to generate images with a spatial resolution of 1.5 mm. Each pixel was acquired with a 16 ms integration time, resulting in a 40 dB postdetection SNR. The simplicity and high SNR of the reflective terahertz system are promising steps toward real-time terahertz medical imaging.

Pullulan-hyperproducing color variant strain of Aureobasidium pullulans FB-1 newly isolated from phylloplane of Ficus sp

The studies were carried out for the isolation of efficient pullulan producing strains of Aureobasidium pullulans. Five strains were isolated from phylloplane of different plants. Amongst these, three were producing black pigment melanin, while the remaining two produced pink pigment. These two color variant isolates of A. pullulans were designated as FB-1 and FG-1, and obtained from phylloplane of Ficus benjamina and Ficus glometa, respectively. The parameters employed for the identification of the isolates included morphology, nutritional assimilation patterns and exopolysaccharide (EPS) production. Isolates were compared with standard cultures for EPS production. A. pullulans FB-1 was the best producer of pullulan giving up to 1.9, 1.4 and 1.7 times more pullulan than the control of A. pullulans NCIM 976, NCIM 1048 and NCIM 1049, respectively. The IR spectra of the isolates and standard strains revealed that the polysaccharide was pullulan, but not aubasidan. The study also supported the fact that A. pullulans is a ubiquitous organism and phylloplane being the important niche of the organism.

Optimization of medium and process parameters for the production of inulinase from a newly isolated Kluyveromyces marxianus YS-1

A newly isolated strain of Kluyveromyces marxianus YS-1 was used for the production of extra cellular inulinase in a medium containing inulin, meat extract, CaCl2 and sodium dodecyl sulphate (SDS). Fermentation medium pH 6.5, cultivation temperature 30 degrees C and 5% (v/v) inoculum of 12 h-old culture were optimal for enzyme production (30.8 IU/ml) with a fermentation time of 72 h at shake flask level. Raw inulin (2%, w/v) extracted from dahlia tubers by processing at 15 kg/cm2 for 10 min was optimum for bioreactor studies. Maximum enzyme production (55.4 IU/ml) was obtained at an agitation rate of 200 rpm and aeration of 0.75 vvm in a stirred tank reactor with a fermentation time of 60 h.

Removal of toluene vapour using agro-waste as biofilter media

Biodegradation of toluene vapour was investigated in a laboratory scale biofilter packed with cylindrical pieces of yellow-gram (Cajanus cajan) stalk. Inlet concentrations and volumetric flow rates of toluene were varied from 2.56 to 34.73 g/m3 and 0.18 to 0.24 m3/h, respectively. The steady state was achieved within seven days and the degradation of toluene followed an exponential behaviour with time. Elimination capacity increased and tended towards a constant value but removal efficiency decreased with increase in inlet toluene loading. Depending upon loading rate, the process was either mass transfer or reaction-controlled.

A time-sequence functional analysis of mating behaviour and genital coupling in Drosophila: role of cryptic female choice and male sex-drive in the evolution of male genitalia

Male genitalia in Drosophila exemplify strikingly rapid and divergent evolution, whereas female genitalia are relatively invariable. Whereas precopulatory and post-copulatory sexual selection has been invoked to explain this trend, the functional significance of genital structures during copulation remains obscure. We used time-sequence analysis to study the functional significance of external genitalic structures during the course of copulation, between D. melanogaster and D. simulans. This functional analysis has provided new information that reveals the importance of male-driven copulatory mechanics and strategies in the rapid diversification of genitalia. The posterior process, which is a recently evolved sexual character and present only in males of the melanogaster clade, plays a crucial role in mounting as well as in genital coupling. Whereas there is ample evidence for precopulatory and/or post-copulatory female choice, we show here that during copulation there is little or no physical female choice, consequently, males determine copulation duration. We also found subtle differences in copulatory mechanics between very closely related species. We propose that variation in male usage of novel genitalic structures and shifts in copulatory behaviour have played an important role in the diversification of genitalia in species of the Drosophila subgroup.

Enhanced adaptive evolution of sperm-expressed genes on the mammalian X chromosome

Genes on the mammalian X chromosome may be under unique evolutionary pressure due to their hemizygous expression in males. Since any recessive deleterious mutation would immediately be expressed in males and, therefore, efficiently removed from the population, selective constraint could be more pronounced in X-linked genes. Conversely, if a recessive mutation were beneficial, its immediate exposure to selection would be advantageous, and would facilitate adaptive evolution. We tested for positive selection in a total of 86 genes using a maximum likelihood approach, including 40 sperm-expressed and 46 non-sperm, tissue-specific genes. We find evidence to suggest that X-linkage enhances the effects of positive selection in sperm-expressed genes in terms of the number of codons affected, and report a general trend for positively selected genes to reside on the X chromosome rather than on the autosomes. Our data suggest that hemizygous expression in males makes the X chromosome a preferred location for positively selected sperm genes that do not require postmeiotic transcription.

Performance evaluation of an agro waste based biofilter treating toluene vapours

Biodegradation of toluene vapour was investigated for 162 days in a laboratory scale biofilter packed with maize waste. Inlet concentration of toluene was varied from 2.86 to 5.79 g m(-3) and the volumetric flow rate of toluene loaded air from 0.09 to 0.3 m3 h(-1). The media bed height used in the study was 0.63 m. Plug flow behaviour of the bed was confirmed by RTD experiments. The steady state was achieved in 18 days. Depending upon initial loading rates, removal efficiency ranging from 54.5 to 85.3% and elimination capacity ranging from 43.47 to 174.6 g h(-1) m(-3) were observed during steady state operation. The dynamic behaviour of the biofilter was evident from response to change in process conditions. The stability of the biomass was evident from the fast response of the biofilter to shutdown and restart operations. High value of carbon recovery confirms the effective biodegradation in the biofilter. In the startup period, the pressure drop in the bed increased for some time after that it tended towards a constant value.

Ultrasound crack detection in a simulated human tooth

OBJECTIVE

Currently, diagnosis of cracked teeth generally depends upon the overall clinical assessment, or on exclusion of other clinical possibilities, not primarily on the direct identification of cracks themselves. Owing to its short wavelength in hard tissues and associated high resolution, ultrasound has the potential to allow detection of cracks within tooth structure. However, ultrasound detection of dental cracks has not previously been achieved. The purpose was to determine if an ultrasound imaging system was capable of imaging cracks in simulated tooth structure.

METHODS

A complete ultrasound system including a novel transducer made of PLZT-98, a novel gallium-indium alloy coupling agent, and customized electronic and digital signal processing (DSP) algorithms was developed for the specific application of optimizing crack detection within teeth. A simulated tooth with a known and uniform internal structure and acoustic properties similar to those of natural enamel and dentin was designed to model a human tooth with a crack located in dentin deep to the dentino-enamel junction (DEJ). The distance between the DEJ and a crack of the simulated tooth were calculated.

RESULTS

The system unequivocally distinguished between areas with and without a simulated crack.

CONCLUSION

A unique ultrasound dental crack detection system using a novel transducer; a novel coupling agent; and customized electronic and digital signal processing (DSP) algorithms has been validated in a simulated tooth.

Ultrasound-assisted fabrication of nanoporous CdS films

A new method for fabricating nanoporous CdS films is reported. It involves exposing the CdS solution with ultrasound waves during the process of dip coating. Indium tin oxide (ITO)-coated glass and plastic (commercial transparency) were used as substrates. In each case three different precursors were used for dip coating. The precursors used were CdCl2 and thiourea in one case and CdS nanoparticles prepared by sonochemical and microwave-assisted methods in the other two cases. X-ray diffraction studies performed on these powders show a phase corresponding to cubic CdS. The Field Emission Scanning Electron Microscopy (FE-SEM) images of the films on plastic showed uniform pores with a diameter of 80 nm for all three methods. Optical absorption measurements indicated a blue shift and multiple peaks in the absorption curve. The FE-SEM observations of the films on an ITO/glass substrate indicated a crystalline film with voids. The UV-vis absorption results indicated a blue shift in the absorption with an absorption edge at 435, 380, and 365 nm for CdS films made by solution growth, sonochemical, and microwave routes, respectively. The magnitude of the absorption is dependent on film thickness, and the observed blue shift in the absorption can be explained on the basis of quantum confinement effects.