A phenomological model is described here to study the effect of size, shape and phonon scattering on the thermal conductivity of nanostructures. Using the classical model proposed by Guisbiers
et al
...(
Phys. Chem. Chem. Phys.
12
, 7203 (
2010
),
J. Phys. Chem. C
112
, 4097 (
2008
)) in terms of the melting temperature of nanostructures, the expression for variation of thermal conductivity is obtained in terms of shape and size parameter. An additional term is included in the expression of thermal conductivity to consider the impact of phonon scattering due to the surface roughness with a decrease in size. The expression of thermal conductivity is obtained for spherical nanosolids, nanowires and nanofilms. The thermal conductivity is found to decrease in nanostructures in comparison with the counterpart bulk material. The values of thermal conductivity obtained from the present model are found to be close to the available experimental data for different values of roughness parameter which verifies the suitability of the model.
Although the unprecedented efforts the world has been taking to control the spread of the human coronavirus disease (COVID‐19) and its causative aetiology severe acute respiratory syndrome ...coronavirus 2 (SARS‐CoV‐2), the number of confirmed cases has been increasing drastically. Therefore, there is an urgent need for devising more efficient preventive measures, to limit the spread of the infection until an effective treatment or vaccine is available. The preventive measures depend mainly on the understanding of the transmission routes of this virus, its environmental stability, and its persistence on common touch surfaces. Due to the very limited knowledge about SARS‐CoV‐2, we can speculate its stability in the light of previous studies conducted on other human and animal coronaviruses. In this review, we present the available data on the stability of coronaviruses (CoVs), including SARS‐CoV‐2, from previous reports to help understand its environmental survival. According to available data, possible airborne transmission of SARS‐CoV‐2 has been suggested. SARS‐CoV‐2 and other human and animal CoVs have remarkably short persistence on copper, latex and surfaces with low porosity as compared to other surfaces like stainless steel, plastics, glass and highly porous fabrics. It has also been reported that SARS‐CoV‐2 is associated with diarrhoea and that it is shed in the faeces of COVID‐19 patients. Some CoVs show persistence in human excrement, sewage and waters for a few days. These findings suggest a possible risk of faecal–oral, foodborne and waterborne transmission of SARS‐CoV‐2 in developing countries that often use sewage‐polluted waters in irrigation and have poor water treatment systems. CoVs survive longer in the environment at lower temperatures and lower relative humidity. It has been suggested that large numbers of COVID‐19 cases are associated with cold and dry climates in temperate regions of the world and that seasonality of the virus spread is suspected.
A phenomenological model based on thermodynamical variables is used to analyze the optical properties of nanomaterials. The expression of cohesive energy given by Qi and Wang model is extended to ...study the variation of the energy band gap, vibrational frequency, and static dielectric constant with size for nanoparticles, nanowires, and nanofilms. The energy bandgap is observed to increase in nanostructures with a reduction in size while the reduction in the vibrational frequency of nanostructures is found with a decrease in size from model calculations. The dielectric constant is also found decreasing with the size reduction of the nanostructure to the nanoscale. As the number of surface atoms changes with change in the shape of the nanomaterial, the shape effect on optical properties is also studied. The size and shape effect are found prominent in nanostructures up to the size limit of approximately 30 nm; however, the effect of size and shape becomes less significant as the size is more than 30 nm. The model predictions are consistent with the available experimental and simulated trend which supports the validity of the model theory.
Five mock theta functions of S. Ramanujan are combinatorially interpreted by means of certain associated lattice path functions and antihook differences. These results provide new combinatorial ...interpretations of five Ramanujan mock theta functions. By using a bijection between the associated lattice path functions and the (
n
+
t
)-color partitions and then between the associated lattice path functions and the weighted lattice path functions, we extend the works by Agarwal and Agarwal and Rana to five new 3-way combinatorial identities. These results are further extended to 4-way combinatorial identities by using a bijection between the (
n
+
t
)-color partitions and the partitions with certain antihook differences. These interesting results present elegant combinatorial links between Ramanujan’s mock theta functions, (
n
+
t
)-color partitions, weighted lattice paths, associated lattice paths, and antihook differences.
Summary Background Surface contamination has been implicated in the transmission of certain viruses, and surface disinfection can be an effective measure to interrupt the spread of these agents. Aim ...To evaluate the in-vitro efficacy of hydrogen peroxide vapour (HPV), a vapour-phase disinfection method, for the inactivation of a number of structurally distinct viruses of importance in the healthcare, veterinary and public sectors. The viruses studied were: feline calicivirus (FCV, a norovirus surrogate); human adenovirus type 1; transmissible gastroenteritis coronavirus of pigs (TGEV, a severe acute respiratory syndrome coronavirus SARS-CoV surrogate); avian influenza virus (AIV); and swine influenza virus (SwIV). Methods The viruses were dried on stainless steel discs in 20- or 40-μL aliquots and exposed to HPV produced by a Clarus L generator (Bioquell, Horsham, PA, USA) in a 0.2-m3 environmental chamber. Three vaporized volumes of hydrogen peroxide were tested in triplicate for each virus: 25, 27 and 33 mL. Findings No viable viruses were identified after HPV exposure at any of the vaporized volumes tested. HPV was virucidal (>4-log reduction) against FCV, adenovirus, TGEV and AIV at the lowest vaporized volume tested (25 mL). For SwIV, due to low virus titre on the control discs, >3.8-log reduction was shown for the 25-mL vaporized volume and >4-log reduction was shown for the 27-mL and 33-mL vaporized volumes. Conclusion HPV was virucidal for structurally distinct viruses dried on surfaces, suggesting that HPV can be considered for the disinfection of virus-contaminated surfaces.
Carotid webs may cause recurrent ischemic stroke. We describe the prevalence, demographics, clinical presentation, imaging features, histopathology, and stroke risk associated with this ...under-recognized lesion.
A carotid web was defined on CTA as a thin intraluminal filling defect along the posterior wall of the carotid bulb just beyond the carotid bifurcation on oblique sagittal section CTA that was seen as a septum on axial CTA. Using a prospective case series from April 2013 to April 2014, we describe the demographics, spectrum of imaging features on CTA, and histopathology of these carotid webs. From a retrospective analysis of patients at our center from May 2012 to April 2013 who had a baseline head and neck CTA followed by a brain MR imaging within 1-2 days of the CTA, we determine the period prevalence of carotid webs and the prevalence of ipsilateral stroke on imaging.
In the prospective series, the mean age was 50 years (range, 41-55 years); 5/7 patients were women. Recurrent stroke was seen in 5/7 (71.4%) patients with the carotid web; time to recurrence ranged from 1 to 97 months. Histopathology suggested a high probability of fibromuscular dysplasia. In the retrospective series, carotid webs were seen in 7/576 patients for a hospital-based-period prevalence of 1.2% (95% CI, 0.4%-2.5%). Two of these 7 patients had acute stroke in the vascular territory of the carotid web.
A carotid web may contribute to recurrent ischemic stroke in patients with no other determined stroke mechanism. Intimal variant fibromuscular dysplasia is the pathologic diagnosis in most cases. The prevalence of carotid web is low, while the optimal management strategy remains unknown.
In this work, citric acid (CA) modified starch/gelatin composite films were prepared by mixing modified starch and gelatin in different proportions (1:0, 1:1, 1:4, 4:1 and 0:1). Blending of ...chemically modified starch with food grade CA and gelatin as second polymers were studied as a new and novel approach for fabrication of eco-friendly composite films with excellent packaging properties. Taking considerations of improvement in functional properties of the films, a series of starch films were derived using CA–starch and gelatin using solution casting approach. Influence of CA (0.5%, 1%, 3%, 5% and 7% w/w of total starch) on functional properties (moisture content, solubility, swelling index, moisture migration rate, moisture absorption, opacity and mechanical properties) were studied. FTIR and SEM analysis were utilized to characterize the interaction between the starch chains and surface morphology of films. Findings revealed that functional properties (aqueous solubility, swelling index, and moisture barrier properties) significantly (
p <
0.05) improved as CA content increased. Composite films with CA–starch/gelatin of the ratio (4:1) revealed excellent functional properties. FTIR spectra illustrated strong interaction between the starch chains in the starch films. SEM analysis showed that gelatin exhibited good compatibility in the composite films. Therefore obtained composite films possessed a homogenious, dense and compact networks. In conclusion, CA and gelatin made better starch film properties and broadened the potential applications in the food packaging.
Newcastle disease (ND), caused by Newcastle disease virus (NDV), is a contagious disease that affects a variety of domestic and wild avian species. Though ND is vaccine-preventable, it is a ...persistent threat to poultry industry across the globe. The disease represents a leading cause of morbidity and mortality in chickens. To better understand the epidemiology of NDV among commercial and backyard chickens of Odisha, where chicken farming is being prioritized to assist with poverty alleviation, a cross-sectional study was conducted in two distinct seasons during 2018. Choanal swabs (n = 1361) from live birds (commercial layers, broilers, and backyard chicken) and tracheal tissues from dead birds (n = 10) were collected and tested by real-time reverse transcription polymerase chain reaction (RT-PCR) for the presence of matrix (M) and fusion (F) genes of NDV. Risk factors at the flock and individual bird levels (health status, ND vaccination status, geographical zone, management system, and housing) were assessed using multivariable logistic regression analyses. Of the 1371 samples tested, 160 were positive for M gene amplification indicating an overall apparent prevalence of 11.7% (95% CI 10.1-13.5%). Circulation of virulent NDV strains was also evident with apparent prevalence of 8.1% (13/160; 95% CI: 4.8-13.4%). In addition, commercial birds had significantly higher odds (75%) of being infected with NDV as compared to backyard poultry (p = 0.01). This study helps fill a knowledge gap in the prevalence and distribution of NDV in apparently healthy birds in eastern India, and provides a framework for future longitudinal research of NDV risk and mitigation in targeted geographies-a step forward for effective control of ND in Odisha.
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