An uncommon yet highly symmetric crystal form of a Mn-based heteropolytungstate (Mn-HPT), Mn7(MnW12O42(OH)4)·8H2O, has been synthesized by a unique solvothermal method at 180 °C for 6 h. The nature ...of the solvent (water/ethanol = 50/50 by volume) and the presence of citric acid were the key reasons for the formation of the Mn-HPT phase and its hollow spherical morphology under the said experimental conditions. Combined powder X-ray diffraction analysis and field emission scanning electron miroscopy (FESEM) analysis reveals that the structure (cubic, space group Im3) consisted of MnW12O4210– polyanion with Mn in a central 12-coordinated cavity, which cross-linked three dimensionally with other MnO6 octahedra, to form the characteristic rhombododecahedron shaped particles of size ∼150 nm. Each polyanion was made of six pair of face shared WO6 dimers (W2O9) with mean W···W separation of 2.98 Å. The WO6 octahedrons were tilted to an O–W–O angle of 99.1° with four different types of W–O bonds. The structure was further characterized by thermogravimetric (TG), infrared (IR), Raman, and X-ray photoelectron spectroscopy (XPS) study. UV–vis diffuse reflectance spectroscopy (DRS) analysis suggests that the material essentially was an indirect band gap semiconductor with E g = 2.33 and 2.93 eV corresponding to the transitions from two different sets of nonbonding HOMO (O 2p) to the π* LUMO (W 5d). Room temperature photoluminescence (PL) analysis further delineates the HOMO–LUMO transition in the blue (412 nm) to green (525 nm) region with characteristic mean decay lifetime ∼8 ns.
Cloud radar reflectivity profiles can be an important measurement
for the investigation of cloud vertical structure (CVS). However, extracting
intended meteorological cloud content from the ...measurement often demands an
effective technique or algorithm that can reduce error and observational
uncertainties in the recorded data. In this work, a technique is proposed to
identify and separate cloud and non-hydrometeor echoes using the radar
Doppler spectral moments profile measurements. The point and volume
target-based theoretical radar sensitivity curves are used for removing the
receiver noise floor and identified radar echoes are scrutinized according
to the signal decorrelation period. Here, it is hypothesized that cloud
echoes are observed to be temporally more coherent and homogenous and have a
longer correlation period than biota. That can be checked statistically
using ∼ 4 s sliding mean and standard deviation value of
reflectivity profiles. The above step helps in screen out clouds critically
by filtering out the biota. The final important step strives for the
retrieval of cloud height. The proposed algorithm potentially identifies
cloud height solely through the systematic characterization of Z variability
using the local atmospheric vertical structure knowledge besides to the
theoretical, statistical and echo tracing tools. Thus, characterization of
high-resolution cloud radar reflectivity profile measurements has been done
with the theoretical echo sensitivity curves and observed echo statistics
for the true cloud height tracking (TEST). TEST showed superior performance in
screening out clouds and filtering out isolated insects. TEST constrained with
polarimetric measurements was found to be more promising under high-density biota
whereas TEST combined with linear depolarization ratio and spectral width perform potentially to
filter out biota within the highly turbulent shallow cumulus clouds in the
convective boundary layer (CBL). This TEST technique is promisingly simple
in realization but powerful in performance due to the flexibility in
constraining, identifying and filtering out the biota and screening out the
true cloud content, especially the CBL clouds. Therefore, the TEST algorithm is superior for screening out the low-level clouds that are strongly linked to the
rainmaking mechanism associated with the Indian Summer Monsoon region's
CVS.
•Ka-band radar polarimetric signatures of Melting region were investigated in WG.•Radar reflectivity is corrected for different attenuations to improve data quality.•Characterization of seeder-feeder ...mechanism in the WG.
During the Indian summer monsoon, high temporal and spatial resolution observations from Ka-band dual-polarization radar deployed in the Western Ghats (WG), India are utilized to investigate the vertical structure of the stratiform precipitating system. First, the radar reflectivity (Z) measurements are corrected for rain attenuation, based on the relationship between specific attenuation (A) and Z. The disdrometer dataset is used to calculate the expected value of A at Ka-band for a given Z using microwave scattering simulation. The radar data are also corrected for wet radome transmission loss, gaseous, and melting layer (ML) attenuation. Within the ML, a change in Z and other radar polarimetric variables suggest hydrometeors phase change. In addition to Z, polarimetric measurements such as differential reflectivity (ZDR), linear depolarization ratio (LDR), and copolar correlation coefficient between horizontal and vertical channel (ρHV) are used to determine the ML height. Ka-band polarimetric radar signatures near the ML are characterized by a low ρHV (∼0.93), high Z (∼25–30 dBZ), ZDR (∼3 dB), and LDR (∼ −15 dB) values. In the stratiform precipitation region, well-defined fall streaks are observed above ML, which descends through 0 °C isotherm into the rain region. When the fall streaks are present above the ML, Z increases below the ML, indicating a seeder-feeder mechanism. Because there is little observational evidence concerning the vertical distribution of stratiform clouds over the Indian subcontinent, the current study may help to understand stratiform clouds and the ice processes that occur within them.
Crystallization of manganese (Mn2+) and tungstate (WO4 2–) ions in the presence of citric acid under different water/ethanol mixtures has been systematically investigated under solvothermal ...conditions. A unique phase transition between two polymorphic phases, formulated as MnWO4, manganese tungstate, and Mn8W12O42(OH)4·8H2O, manganese heteropolytungstate (Mn-HPT), was observed along with a striking morphological alteration from rigid to hollow microsphere. The effective coordination of citrate ion to tungstate (tungstate–citrate 1:1 complex) in aqueous solution before the hydrothermal treatment drives the system to nucleate the less symmetric, monoclinic (space group: P2/c) MnWO4 phase, which is the thermodynamically preferred polymorph. However, formation of the tungstate–citrate complex can be tuned by changing the dielectric constant of the solvent or by decreasing the citric acid to tungstate molar ratio. Results show that both conditions assist in the formation of the kinetically stable, more symmetric, cubic Mn-HPT (space group: Im3̅) phase at the same reaction temperature and time. The formation of the Mn-HPT phase is mediated by a kinetically advantageous crystallization process from an amorphous precursor, while later on it gradually converted into more stable MnWO4 phase according to “Ostwald rule of successive phase transformation”. Optimum reaction conditions for the synthesis and plausible growth mechanisms of both microspheres were proposed on the basis of solvent, reaction time, temperature, and the presence of citric acid. Magnetic properties of both samples were investigated in order to illuminate the nature of magnetic interaction within the crystal lattice.
Background: For successful management of acute appendicitis, early diagnosis and intervention is needed. Incorrect diagnosis may allow significantly increased morbidity and mortality. Several studies ...across the globe shows that Modified Alvarado Scoring System (MASS) does not need high end instrument and can be done in emergency situation for accessing acute appendicitis and reducing the chances of unnecessary surgery. To access the efficacy of MASS for diagnosis of acute appendicitis in remote areas with primary health care facilities, present study was done at Siliguri of Darjeeling district of West Bengal which was 580 km distant from state capital (Kolkata).Methods: A cross sectional study over a period of 16 months was conducted among the patients admitted at North Bengal Medical College and Hospital suspected to have acute appendicitis. The diagnosis was confirmed by histopathological examination. Written consent was obtained from the patients before commencement of the study. MASS was applied to the patients and the results were compared with histopathological findings. Appropriate statistical analysis has been done by SPSS (version 16.0).Results: A total of 75 patients (44 males and 31 females) were considered. The sensitivity and specificity of MASS in this study were 75.86% (71.43% for males and 80% for females) and 82.61% (80% for males and 87.5% for females) respectively. Study revealed statistically significant (p<0.000) association between Histopathological report and MASS.Conclusions: To reduce the chances of negative appendectomy and for better diagnosis of appendicitis, MASS may be more useful at primary health care centres those are located in remote areas as it was very simple, easy and cost effective.
Exposing cells to excess metal concentrations well beyond the cellular quota is a powerful tool for understanding the molecular mechanisms of metal homeostasis. Such improved understanding may enable ...bioengineering of organisms with improved nutrition and bioremediation capacity. We report here that Chlamydomonas reinhardtii can accumulate manganese (Mn) in proportion to extracellular supply, up to 30-fold greater than its typical quota and with remarkable tolerance. As visualized by X-ray fluorescence microscopy and nanoscale secondary ion MS (nanoSIMS), Mn largely co-localizes with phosphorus (P) and calcium (Ca), consistent with the Mn-accumulating site being an acidic vacuole, known as the acidocalcisome. Vacuolar Mn stores are accessible reserves that can be mobilized in Mn-deficient conditions to support algal growth. We noted that Mn accumulation depends on cellular polyphosphate (polyP) content, indicated by 1) a consistent failure of C. reinhardtii vtc1 mutant strains, which are deficient in polyphosphate synthesis, to accumulate Mn and 2) a drastic reduction of the Mn storage capacity in P-deficient cells. Rather surprisingly, X-ray absorption spectroscopy, EPR, and electron nuclear double resonance revealed that only little Mn2+ is stably complexed with polyP, indicating that polyP is not the final Mn ligand. We propose that polyPs are a critical component of Mn accumulation in Chlamydomonas by driving Mn relocation from the cytosol to acidocalcisomes. Within these structures, polyP may, in turn, escort vacuolar Mn to a number of storage ligands, including phosphate and phytate, and other, yet unidentified, compounds.
Football is, arguably, the most globalized sport in the world. Since the official date of its foundation, back in 1863, it has spread around the planet, reaching almost every country. Over time, ...Football roots grew so attached to society that it is a valid indicator to understand how the social order responds to general crises. In 1911 in the IFA Shield tournament when Mohun Bagan defeated the British side, East Yorkshire Regiment, and took home the shield. This was Indian football's 'Lagaan' moment. Even during the period between 1950 and 1962 is often considered to be the 'Golden Era' of Indian football, so much so that India was often referred to as the 'Brazil of Asia'. But where are we now? The latest FIFA rankings places India at the 105th position. We are a country of 1.3 billion people failing to produce a well-built set of players, who can challenge European, South American, or even our South Asian counterparts consistently. So, it certainly begs the question: Where are we going wrong?
•Image texture analysis is used to characterize micrographs and fractographs.•Fractal analysis, GLCM and RLS analysis have been carried out.•Systematic variation of texture descriptors with ageing ...temperature.•Correlation of texture descriptors vis-à-vis mechanical properties.•The concept of automatic characterization with machine vision has been highlighted.
Texture analyses methods incorporating fractal analysis using box-counting, grey level co-occurrence matrix (GLCM) technique and run length statistical (RLS) analysis technique have been carried out to automatically characterize micrographs and fractographs of Cu-strengthened high-strength low alloy (HSLA) steel. The selected steel has been solution treated and water quenched followed by ageing at different temperatures. Tensile tests have been carried out for water quenched and aged specimens. Microstructural and fractographic analyses are made using scanning electron microscope. Ten texture features from the three texture analyses methods are extracted to correlate with the observed mechanical properties. The obtained image texture features of both micrographs and fractographs have been compared with the estimated mechanical properties. The results obtained from the investigation reveal that there is a systematic correlation of the mechanical properties and image texture features with ageing temperatures.
Abstract The Delirium Motor Subtype Scale (DMSS) was developed by discerning the best differentiating motor activity symptoms from the Delirium Motor Checklist (DMC), a compilation of psychomotor ...symptoms from other subjective scales. To broaden its validation we replicated the original work done in a palliative care population in a psychiatric referral population. 100 consecutive C/L Psychiatry referrals with DSM-IV delirium in an Indian general hospital were assessed with the Delirium Rating Scale-Revised-98 (DRS-R98) and DMC and compared to 60 nondelirious hospitalized controls. Disturbances of motor activity were almost invariably present in patients with delirium and at a much higher frequency than in nondelirious control subjects. Principal components analysis identified 5-factors for the DMC where Factor 1 explained 37.3% of the variance and correlated significantly with DRS-R98 motor items. Items loading at >0.65 were selected for the replication scale if they also either correlated significantly with DRS-R98 motor items or were significantly more frequent in delirious patients vs. controls. The resultant scale comprised 12 items (five hyperactive and seven hypoactive) and was similar to the original DMSS. Combining motor items from the original DMSS and replicated version produced a 13-item amended DMSS that may have broader generalizability than the original DMSS.
Nanocrystalline tantalum carbide (TaC) particles of average size ~15 nm dispersed in silica matrix, have been synthesized by the carbothermal reduction of Ta
2
O
5
over a range of temperature ...1,100–1,360 °C in Ar atmosphere. Investigation of the stability diagram of carbon saturated Ta–O–N system suggests that the TaC phase can be successfully synthesized within the SiO
2
matrix when the partial pressure of O
2
and N
2
are restricted to approximately lower than 1.25 and 0.0001 atm. respectively. Two different synthesis routes are investigated in the present study which differ fundamentally in the order of addition of the precursors, tetraethyl orthosilicate (TEOS) and tantalum isopropoxide (Ta-iso). Rietveld refinement analyses of the powder X-ray diffraction data are carried out for the quantitative estimation of the two phases in the samples. The yield of TaC increases from 18 to 52 % when both TEOS and Ta-iso are added simultaneously to the water compared to the process where TEOS is added first to the water followed by the delayed addition of Ta-iso. Samples are further characterized by field emission scanning electron microscopy and high resolution transmission electron microscopy.
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