Antimicrobial activity of silver nanoparticles, which were synthesized by tri-sodium citrate assisted chemical approach, was evaluated. Chemical approach used for the synthesis of silver ...nanoparticles it was based on diminishment of silver nitrate in nearness of trisodium citrate without using any other capping and stabilizing agents. During the synthesis, four samples of silver nanoparticles were collected for comparative studies. The presence of silver nanoparticles was affirmed by analyzing the sample with X-ray diffraction, transmission electron microscopy, dynamic light scattering and ultra violet visible spectroscopy. Antimicrobial activity of some silver nanoparticle samples against two bacterial strains including Bacillus subtilis (which is Gram positive bacteria), Escherichia coli (which is Gram negative bacteria) and two fungal (yeast) strains namely Saccharomyce scerevisiae, and Candida albicans was determined. The silver nanoparticles showed the most significant inhibition activity against bacterial strains (Escherichia coli and Saccharomyces cerevisiae) in comparison to that activity towards fungal strains.
•Synthesis of silver nanoparticles (AgNPs) of different size by advanced chemical approach was applied.•Phases of pure Ag were observed by UV-Vis spectroscopy, XRD and TEM-SAD.•Antimicrobial activity of AgNPs against several bacterial and several fungal strains was determined.•Highest sensitivity towards AgNPs was observed for Escherichia coli, Saccharomyces cerevesiae and Candida albicans.
This study investigates the effect of a brazing thermal cycle on the microstructure and mechanical properties of Fe–Cr–Mn–Ni–C stainless steel using microstructural examination, X-ray diffraction, ...ferrite content, hardness, impact, and tensile testing. Stainless steel was exposed to a high-temperature brazing thermal cycle of 1180 °C for 20 min, followed by different cooling practices, including furnace, air, and water quenching. The microstructure of the as-received steel mainly comprised austenite, ferrite, sigma phase, and carbides. Air and furnace cooling resulted in the formation of a sigma phase by decomposition of the ferrite phase. The amount of sigma phase varied depending on the cooling rate, which in turn influenced the mechanical properties. Water-quenched specimens were free from the sigma phase, while furnace-cooled specimens had a sigma phase of 9%. In other conditions, the sigma phase was in the range of 2.5–4%. Furnace-cooled specimens with higher sigma phase exhibited lower tensile ductility and impact strength compared to other conditions due to the brittle nature of the sigma phase. Re-solution treatment of furnace-cooled specimens at 1050 °C reduced the sigma phase and restored the mechanical properties.
In the field of communication, Mobile Ad-hoc networks (MANET) have become popular and widely used. However, there are many security challenges in communication through these networks due to the ...presence of malicious nodes. The aim of this article is to present a novel adaptive threshold trust based approach for isolating malicious nodes to establish secure routing between source and destination. Many existing cryptography methods are complex and do not properly address the elimination of malicious nodes. Several trust-dependent mechanisms have been proposed that supplement old traditional cryptography- related security schemes. But it is observed that most of these trust based approaches are using direct trust and comparing with static trust threshold. This article proposes a novel method, secured trust with adaptive threshold (STAT) that uses the Adaptive threshold technique (APTT) combined along with secure trust based approach (STBA) to evaluate the node trustworthiness for efficient routing. Secure trust for a node is calculated based upon three tier observations that includes direct, neighbor, self-historical to enrich the trust factor and adaptive trust threshold is determined based upon network parameters dynamically. Node’s secure trust is compared with adaptive trust threshold computed to isolate the malicious nodes from routing. The proposed method is compared with two cases where routing is performed without any trust calculation and routing with trust calculation and compared with static trust threshold approach. Results show significant performance of the proposed work in terms of metrics like packet delivery ratio, delay, throughput, false positive detection ratio and packet drop ratio. The proposed method STAT effectively isolates the malicious nodes and establishes secure routing.
A conserved hypothetical protein, Sll1130, is a novel transcription factor that regulates the expression of major heat-responsive genes in Synechocystis sp. PCC6803. Synechocystis exhibited an ...increased thermotolerance due to disruption of sll1130. Δsll1130 cells recovered much faster than wild-type cells after they were subjected to heat shock (50°C) for 30 min followed by recovery at 34°C for 48 h. In Δsll1130 cultures, 70% of the cells were viable compared with the wild-type culture in which only 30% of the cells were viable. DNA microarray analysis revealed that in Δsll1130, expression of the heat-responsive genes such as htpG, hspA, isiA, isiB and several hypothetical genes were up-regulated. Sll1130 binds to a conserved inverted-repeat (GGCGATCGCC) located in the upstream region of the above genes. In addition, both the transcript and protein levels of sll1130 were immediately down-regulated upon shift of wild-type cells from 34 to 42°C. Collectively the results of the present study suggest that Sll1130 is a heat-responsive transcriptional regulator that represses the expression of certain heat-inducible genes at optimum growth temperatures. Upon heat shock, a quick drop in the Sll1130 levels leads to de-repression of the heat-shock genes and subsequent thermal acclimation. On the basis of the findings of the present study, we present a model which describes the heat-shock response involving Sll1130.
Background: Human height is a classic polygenic trait and currently available data explains only 10% of the phenotypic variation in height. Almost 60%-80% of the children coming to pediatric and ...endocrinology outpatient department for the evaluation of short stature are still labeled as idiopathic. Objectives: The aim of this study is to identify various chromosomal alterations causing idiopathic short stature (ISS) and short stature with dysmorphic features not pertaining to known genetic syndromes. Materials and Methods: After exclusion of all nutritional, systemic, endocrine, and syndromic causes of short stature, 19 patients with height <2 standard deviation scores were subjected to chromosomal microarray (CMA) study using Affymetrix CytoScan 750K array and CMA Scanner 3000 platform. Results: We identified total 61 copy-number variant (CNV) and polymorphs (33 gains, 11 loss, and 17 gain-mosaics) not described as normal variants in database of genomic variations. We identified SHOX haploinsufficiency as a cause of short stature in two patients, whereas one patient was gain-mosaic for SHOX. All three had normal conventional karyotype. One of these patients also had deletion of PAX3, which could be the cause of both short stature and associated mild intellectual impairment in this patient. We also found a long noncoding RNA, namely, KIAA0125 and a pseudogene ADAM6 in 18 out of our 19 patients which might have a regulatory role. Conclusion: This study shows that CMA is a very promising tool for the identification of pathogenic CNVs in patients with ISS. It can also help to identify novel genes controlling height and can open up new insight into pathophysiologic mechanisms underlying ISS, and thus may help to unfold new therapeutic targets for treatment of this condition. The association of CNV having genes for long noncoding RNAs, such as KIAA0125 and pseudogene such as ADAM6 with ISS suggest that they may play a role in controlling the expression of height-related genes and it needs further investigations.
Mobile Ad Hoc Networks, also known as MANETs are the part of networks which utilizes the technologies like Internet of Things. Internet is filled with known as well as unknown sources which are still ...considered as a challenge. Considering the security challenges in the topology, infrastructure and bandwidth of these networks the below secure trust approach is proposed. Among all the existing and proposed approaches to provide the security to these networks seemed lengthy and complex. The study here focuses on the trust factor of the nodes to simulate the challenge of providing the secure transmission. The challenge is approached through calculations from the simulations based on node distribution and its trustworthiness. In order to evaluate the performance of the proposed secure trust mechanism, three scenarios are considered here. Routing between source ad destination without any trust calculation, routing with only direct trust factor and routing with proposed secure trust calculation from the node’s distributions. The goal of proposed method in this paper is about the secure routing for transmission by simulating the important factor Node trustworthiness using new trust mechanism proposed i.e. secure trust. The metrics from the simulations shows the efficient performance of the proposed method.
Field and petrographic studies are carried out to characterize the interactions of mafic and felsic magmas from Pithora region of the northeastern part of the Bastar Craton. The MMEs, syn-plutonic ...mafic dykes, cuspate contacts, magmatic flow textures, mingling and hybridization suggest the coeval emplacement of end member magmas. Petrographic evidences such as disequilibrium assemblages, resorption textures, quartz ocelli, rapakivi and poikilitic textures suggest magma mingling and mixing phenomena. Such features of mingling and mixing of the felsic and mafic magma manifest the magma chamber processes. Introduction of mafic magmas into the felsic magmas before initiation of crystallization of the latter, results in hybrid magmas under the influence of thermal and chemical exchange. The mechanical exchange occurs between the coexisting magmas due to viscosity contrast, if the mafic magma enters slightly later into the magma chamber, then the felsic magma starts to crystallize. Blobs of mafic magma form as MMEs in the felsic magma and they scatter throughout the pluton due to convection. At a later stage, if mafic magma enters the system after partial crystallization of felsic phase, mechanical interaction between the magmas leads to the formation of fragmented dyke or syn-plutonic mafic dyke. All these features are well-documented in the study area. Field and petrographic evidences suggest that the textural variations from Pithora region of Bastar Craton are the outcome of magma mingling, mixing and hybridization processes.
X-ray crystallographic studies of methylene linked Ferrocene-bis(thymine/uracil) conjugates Fc(T:T)M and Fc(U:U)M reveal base dependent 2-D supramolecular assemblies generated via wobble self-pairing ...for bis-thymine and reverse wobble self-pairing for bis-uracil conjugates, differing in architecture from the corresponding butylene spacer linked conjugates
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