Conifer-Derived Metallic Nanoparticles: Green Synthesis and Biological Applications

The use of metallic nanoparticles in engineering and biomedicine disciplines has gained considerable attention. Scientists are exploring new synthesis protocols of these substances considering their small size and lucrative antimicrobial potential. Among the most economical techniques of synthesis of metallic nanoparticles via chemical routes, which includes the use of chemicals as metal reducing agents, is considered to generate nanoparticles possessing toxicity and biological risk. This limitation of chemically synthesized nanoparticles has engendered the exploration for the ecofriendly synthesis process. Biological or green synthesis approaches have emerged as an effective solution to address the limitations of conventionally synthesized nanoparticles. Nanoparticles synthesized via biological entities obtained from plant extracts exhibit superior effect in comparison to chemical methods. Recently, conifer extracts have been found to be effective in synthesizing metallic nanoparticles through a highly regulated process. The current review highlights the importance of conifers and its extracts in synthesis of metallic nanoparticles. It also discusses the different applications of the conifer extract mediated metallic nanoparticles.     

Review of recent advances in anaerobic packed-bed biogas reactors

Biogas digesters have captured many imaginations because they can turn organic wastes from our farms, factories and cities into a valuable source of renewable energy. In addition, the potential of this technology to reduce odors and other environmental concerns of animal feedlots has resulted in much recent interest from researchers and scientists all over the globe.Despite its numerous advantages, the potential of biogas technology could not be fully harnessed or tapped, as certain constraints are also associated with it. Researchers have tried different techniques to enhance gas production. This paper reviews the use of fixed-bed reactors in various fields reported by different researchers using variety of substrates.     

Electrochemical sensors for the determination of Zn ions based on pendant armed macrocyclic ligand

The construction and performance characteristics of polymeric membrane electrodes based on two newly synthesized macrocyclic ligands 6,7:14,15-Bzo₂-10,11-(4-methylbenzene)-[15]-6,8,12,14-tetraene-9,12-N₂-1,5-O₂ (L₁) and 6,7:14,15-Bzo₂-10,11-(4-methylbenzene)-[15]-6,14-diene-9,12-dimethylacrylate-9,12-N₂-1,5-O₂ (L₂) for the quantification of Zn²⁺ ions are described here. Several membranes having different compositions of PVC, plasticizers, ionic additives and ionophores were fabricated and the best response was observed for the membrane having composition L₂:PVC:TBP:NaTPB in the ratio of 4:37:57:2 (w/w; mg). The response characteristics of the membrane based on L₂ were compared with polymeric membrane electrode (PME) as well as with coated graphite electrode (CGE). The electrode exhibits Nernstian slope for Zn²⁺ ions with limits of detection of 3.3 × 10⁻⁷ mol L⁻¹ for PME and 7.9 × 10⁻⁸ mol L⁻¹ for CGE with response time of 12 s and 10 s for PME and CGE respectively. Furthermore, the electrodes generated constant potentials in the pH range of 3.0–8.0 for PME and 2.5–9.0 for CGE. The practical utility of the CGE has been demonstrated by its usage as an indicator electrode in potentiometric titration of EDTA with Zn²⁺ ion solution. The high selectivity of CGE also permits their use in the determination of Zn²⁺ ions in water, biological, milk and tea samples.     

Credibility distribution based R-norm fuzzy information measures in noiseless coding theorems

In the present communication, a parametric R-norm fuzzy entropy of a fuzzy variable and subsequently R-norm fuzzy directed divergence measure of fuzzy variables by taking the credibility distribution measure into account have been proposed along with their proof of validity. Based on the proposed information measures, some new results along with its various properties and the monotonic behavior have been studied in detail. Further, some important results and inequalities related to their corresponding noiseless coding theorems have been well established. Some particular cases related to the proposed fuzzy information measures and fuzzy mean codeword length in terms of existing results have also been discussed. In view the monotonic behavior of the fuzzy mean codeword length, an application to chose the appropriate value of the parameter R to reduce the fuzzy mean codeword length significantly for optimal code has been presented with a possible variability.     

Morphological and Optical Characterization of Sol-Gel Synthesized Ni-Doped ZnO Nanoparticles

Abstract

In this work, Ni-doped ZnO nanoparticles (NPs) were successfully synthesized by sol-gel method. The as-synthesized nanoparticles were characterized to investigate their morphology, structure, purity and optical properties. XRD analysis confirmed the formation of nanoparticles with average particle size of approx. 30?nm. SEM observations show the agglomeration of nanoparticles. The purity of the as-prepared NPs was confirmed by EDX analysis. The defect states were revealed from the photoluminescence (PL) spectra. The overall results obtained indicate that Ni-doped ZnO nanoparticles are promising candidate to fabricate nanoscale optoelectronic devices due to their wide band gap and excellent UV emission properties.     

Anisotropy in impact behavior of Zr-2.5Nb pressure tube alloy

Zr-2.5Nb alloy tubes in cold worked and stress relieved (CWSR) condition serve as pressure boundary for hot coolant in Indian Pressurized Heavy Water Reactor (IPHWR). Due to both microstructural and crystallographic anisotropy, the mechanical properties in general and fracture behavior in particular are anisotropic for this material/component. In this work impact behavior of the pressure tube material was characterized over a range of temperature by impact test using specimens with crack growth direction along axial and transverse directions of the tubes. It has been found that both temperature and orientation have strong influence on the absorbed impact energy.     

Chemical stabilization of gold coated by silver core-shell nanoparticles via electron transfer

Silver nanoparticles are notoriously susceptible to oxidation, yet gold nanoparticles coated in silver exhibit a unique electronic interaction that occurs at the interface of the two metals, leading to enhanced stability properties for the silver shell. In order to probe the phenomenon, the stability of gold nanoparticles coated by silver was studied in the presence of various chloride-containing electrolytes. It was found that a critical silver shell thickness of approximately 1 nm exists that cannot be oxidatively etched from the particle surface: this is in contrast to the observation of complete oxidative etching for monometallic silver nanoparticles. The results are discussed in terms of particle composition, structure and morphology before and after exposing the particles to the electrolytes. Raman analysis of the reporter molecule 3-amino-1,2,4-triazole-5-thiol adsorbed on the particle surface illustrates the feasibility of using gold coated by silver nanoparticle probes in sensing applications that require the presence of high levels of salt. The results provide insight into the manipulation of the electronic and stability properties for gold- and silver-based nanoparticles.     

Design Considerations for High Performance RF Cores Based on Process Variation Study

RF circuits play a vital role in high data rate communication systems. Although at the design stage several considerations are made to ensure that the designed circuit functions as per desired specifications, the effect of process variations on the circuit’s performance is less understood. The parametric variations arising from the various stages of fabrication play a significant role in determining the device characteristics. In this paper, in order to analyze the effect of process variations, we consider a bottom–up approach beginning at the component level for active and passive elements and then move to the circuit level in an RF circuit consisting of both analog and digital components. We take Low Noise Amplifier (LNA) and a Phase Frequency Detector (PFD) which is one of the important building blocks of a Phase Locked Loop (PLL) as case studies for circuit level analysis. In the case of LNA, the performance is analyzed in terms of the S-parameters, gain and Noise Factor on different topologies and for a PFD, an analytical model is developed and the analysis is carried out using the Monte Carlo method to verify the robustness of the circuit elements towards phase noise. Our hierarchical multi-phase analysis technique is shown to provide valuable insights into designing robust RF circuits.