Anisotropic nanomaterials: structure, growth, assembly, and functions

Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications

Safety and Efficacy of Spinal Anaesthesia in Percutaneous Nephrolithotomy

Introduction: Renal stone is one of the common entities occurring in our population. There are different treatment modalities of stones; out of those percutaneous nephrolithotomy is one of the most popular and effective for the renal and upper tract stones. This study is based to compare the safety and efficacy of spinal anaesthesia and general anaesthesia in PCNL. Methods: In a randomized prospective study 60 patients were divided in two groups; group 1 (n=30) underwent PCNL in general anaesthesia and group 2 (n=30) underwent PCNL in spinal anaesthesia in prone position with the conventional technique. Demographic, operative data, post operative complications, patients’ satisfaction rate and follow up complications were recorded and analyzed between two groups. Results: Mean age in group 1 was 39.10±12.45years and 36.10±14.18 in group 2 (P=0.100). Mean stone size in group 1 was 3.75±1.27cm and 3.23±1.36cm in group 2 (P=0.129).Similarly the operative time was 89.10 ± 49.38 min and 62.53±35.91 min in group 1 and group 2 respectively (P=0.042). There was no significant difference between the complications regarding the anaesthesia. Post operative nausea and vomiting were significantly higher in group 1 and headache in group 2 (p=<0.001). Overall patient satisfaction rate was higher in group 2 then in group 1 (p=0.01). Hospital stay in group 1 was 5.27±1.87 days and 4.53±1.88 days in group 2 (p = 0.07). Stone success rate was similar in each group (p =0.50). Conclusions: Spinal anaesthesia is a safe and effective method in performing PCNL. 
 Keywords: general anaesthesia; percutaneous nephrolithotomy; spinal anaesthesia. | PubMe

Electronic and magnetic properties of iridium-based novel Heusler alloys

Half-metallicity and magnetism including exchange splitting are the most significant physical parameters to predict and design a candidate material for spintronic applications. We report here an ab-initio investigation on chemical formation and dynamical stability along with electronic structure and magnetic properties of Ir2Cr (Si, Ge) and IrRhCr (Si, Ge) Heusler alloys. The negative formation and cohesive energies with positive phonon dispersions confirm the stabilities of these alloys. Electronic structure calculations reveal that Ir2Cr (Si, Ge) and IrRhCrSi alloys are half-metallic ferromagnets with unprecedented exchange splitting. In addition, IrRhCrGe also shows semi-metallic nature. All of these materials follow Slater Pauling rule with large magnetic moments and 100% spin-polarization. With Cr bearing the majority of the local magnetic moment and exchange splitting, a ferromagnetic state is more stable than a nonmagnetic state. The electronic charge distribution and population analysis confirm mixed ionic and covalent bonding. The magnetocrystalline anisotropy energy, with the easy magnetization along the [1 1 1] direction, is significantly high in Ir2CrGe. Elastic constants such as shear (G), bulk (B), Young’s moduli, and Poisson’s ratio indicate that the IrRhCrSi and IrRhCrGe alloys are mechanically stable, and Ir2CrSi and Ir2CrGe are mechanically unstable. The Pugh’s (B/G) and Poisson’s ratios confirm that the stable alloys are ductile.This is a manuscript of an article published as Paudel, Ramesh, K. C. Santosh, Sudeep Adhikari, JingChuan Zhu, Sohail Ahmad, Gopi Chandra Kaphle, and Durga Paudyal. "Electronic and magnetic properties of iridium-based novel Heusler alloys." Journal of Magnetism and Magnetic Materials 555 (2022): 169405. DOI: 10.1016/j.jmmm.2022.169405. Copyright 2022 Elsevier B.V. Posted with permission. DOE Contract Number(s): AC02-07CH11358; ACI-1548562; AC02-05CH11231; RGP2/139/43

Distribution of MecA and Erm Genes among Methicillin-resistant Staphylococcus Aureus with Inducible Resistance to Clindamycin

Background: The emergence of Methicillin-resistant Staphylococcus aureus and its ability to confer cross-resistance to macrolide-lincosamide-streptogramin B has complicated the treatment against it. Gene-based studies among phenotypic methicillin-resistant isolates with inducible resistance to clindamycin are less available in Nepal. This work was undertaken to detect the mecA and erm genes among such phenotypes isolated from clinical samples. Methods: S. aureus isolated from different clinical samples was identified by standard microbiological procedures (Gram-staining, colony morphology, and different biochemical tests). Methicillin-resistant and inducible resistant to clindamycin phenotypes were detected by using cefoxitin disc (30 µg) and a double disk diffusion test according to the Clinical and Laboratory Standards Institute guidelines and mecA and erm genes were detected by polymerase chain reaction. Results: Among 120 S. aureus isolates, 51.67% (n=62) were MRSA, and the prevalence of inducibly-resistant, constitutively-resistant and Macrolide-Streptogramin phenotypes were 15.83% (n=19), 28.33% (n=34) and 15.83% (n=19) respectively. While 35.84% (n=43) of isolates showed sensitivity to both antibiotics, erythromycin and clindamycin. Out of 14 inducibly-resistant phenotypes, 57.14% (n=8) were found carrying ermC and 28.57% (n=4) phenotypes contained both ermA and ermC. All phenotypes were positive for the mecA gene. Conclusions: Macrolides-Lincosamide-Streptogramin B resistance was predominant among methicillin-resistant S. aureus. While all isolates with inducible clindamycin resistance harbored mecA gene, most of them also harbored ermC gene. The higher prevalence of inducible-resistant to clindamycin indicated the need for rational use of antimicrobial agents. Keywords: Erm gene; iMLSB resistance; mecA; methicillin-resistance; MRS

Production, Characterization, and Industrial Application of Pectinase Enzyme Isolated from Fungal Strains

Pectinases are the group of enzymes that catalyze the degradation of pectic substances. It has wide applications in food industries for the production and clarification of wines and juices. The aim of this study was to isolate, screen and characterize pectinase from fungi isolated from various soil samples and evaluate its application in juice clarification. Fungal strains were isolated and screened primarily using 1% citruspectin incorporated potato dextrose agar (PDA) and secondarily using pectinase screening agar medium (PSAM) for pectinolytic organisms. The enzyme was produced by submerged state fermentation and assayed using the dinitro salicylic acid (DNS) method. From 20 different soil samples, 55 fungal isolates were screened primarily and, among them, only 14 isolates were subjected for secondary screening. Out of 14, only four strains showed the highest pectinolytic activity. Among four strains, Aspergillus spp. Gm showed the highest enzyme production at a 48-h incubation period, 1% substrate concentration, and 30 °C temperature. The thermal stability assessment resulted that the activity of pectinase enzyme declines by 50% within 10 min of heating at 60 °C. The optimum temperature, pH, and substrate concentration for the activity of enzyme was 30 °C (75.4 U/mL), 5.8 (72.3 U/mL), and 0.5% (112.0 U/mL), respectively. Furthermore, the yield of the orange juice, the total soluble solid (TSS), and clarity (% transmittance) was increased as the concentration of the pectinase increased, indicating its potential use in juice processing. Overall, the strain Aspergillus spp. Gm was identified as a potent strain for pectinase production in commercial scale

Mosquito-borne arboviruses of African origin: review of key viruses and vectors

Abstract Key aspects of 36 mosquito-borne arboviruses indigenous to Africa are summarized, including lesser or poorly-known viruses which, like Zika, may have the potential to escape current sylvatic cycling to achieve greater geographical distribution and medical importance. Major vectors are indicated as well as reservoir hosts, where known. A series of current and future risk factors is addressed. It is apparent that Africa has been the source of most of the major mosquito-borne viruses of medical importance that currently constitute serious global public health threats, but that there are several other viruses with potential for international challenge. The conclusion reached is that increased human population growth in decades ahead coupled with increased international travel and trade is likely to sustain and increase the threat of further geographical spread of current and new arboviral disease