High strain rate properties of polymer matrix composites

The vast differences in strength, ultimate strain and modulus during high strain rate (HSR) deformation of materials have been a very long-standing subject of engineering interest. This thesis deals with characterization of mechanical properties of two composite materials, balanced angle-ply graphite epoxy laminates (fibrous composite) and syntactic foams (particulate composite). The focus of this study is to compare the mechanical properties of these composite materials at high strain rates and quasi-static conditions and to find out the effects of failure modes on HSR mechanical properties of these materials. Split Hopkinson Pressure Bar (SHPB) apparatus is used for the HSR testing of balanced angle-ply IM7/8551-7 graphite/epoxy laminates and syntactic foams at varying strain rates, ranging from 500 s-1 to 1700 s-1. Graphite/epoxy laminates with seven different fiber orientations including longitudinal and transverse are used in this study. Syntactic foams of four different densities are used in order to observe the density effect on the HSR properties. The aspect ratio (L/D) of all the specimens is kept equal to one. Failed specimens are consequently observed under optical and scanning electron microscope in order to understand the fracture modes of these materials. The results of the tests on both materials demonstrate considerable increase in peak strength and the elastic modulus under HSR. It is also observed that the failure strain values vary considerably with increasing strain rate. Fiber orientation, in case of balanced angle-ply graphite epoxy laminates and density in case of syntactic foams are found to influence the HSR mechanical properties and strain rate sensitivity of peak stress. Delamination caused by edge effects is the prominent mechanism of failure for graphite/epoxy specimens whereas vertical cracking through cenospheres is recognized to be the dominant mode of failure for syntactic foam specimens under HSR testing conditions. These results are essential for conducting realistic numerical simulations for safe design of structures

Water-dispersible nanoparticles via interdigitation of sodium dodecylsulphate molecules in octadecylamine-capped gold nanoparticles at a liquid-liquid interface

This paper describes the formation of water-dispersible gold nano-particles capped with a bilayer of sodium dodecylsulphate (SDS) and octadecylamine (ODA) molecules. Vigorous shaking of abiphasic mixture consisting of ODA-capped gold nanoparticles in chloroform and SDS in water results in the rapid phase transfer of ODA-capped gold nanoparticles from the organic to the aqueous phase, the latter acquiring a pink, foam-like appearance in the process. Drying of the coloured aqueous phase results in the formation of a highly stable, reddish powder of gold nanoparticles that may be readily redispersed in water. The water-dispersible gold nanoparticles have been investigated by UV-Vis spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). These studies indicate the presence of interdigitated bilayers consisting of an ODA primary monolayer directly coordinated to the gold nanoparticle surface and a secondary monolayer of SDS, this secondary monolayer providing sufficient hydrophilicity to facilitate gold nanoparticle transfer into water and rendering them water-dispersible

Neonatal tooth with bilateral cleft lip and palate: A case report with review of literature

Natal and neonatal teeth are present in the oral cavity at birth and during the first 30 days of life, respectively. Management of such teeth is a treatment challenge. The incidence of such natal and neonatal teeth is reported to be 1 in every 1125-30,000 births, respectively. Cleft lip and palate (CLP) is a common dentofacial congenital anomaly of the oral cavity and may be present unilaterally or bilaterally. The occurrence of association of such teeth with unilateral and bilateral CLP cases is reported to be 2% and 10%, respectively. The presence of natal/neonatal teeth in the cleft area complicates the child’s health only in few cases. There is a paucity of information in the literature regarding the simultaneous occurrence of neonatal teeth in bilateral CLP cases. The present paper reported the management of a neonatal tooth present in association with complete bilateral CLP in a 12-day-old male child with review of literature

The effect of riluzole alone and in combination with sodium valproate on pentylenetetrazole induced seizures in swiss-albino rats

Background: Riluzole- a glutamate antagonist is known to enhance antiepileptic effects of various other antiepileptic drugs. The present study was undertaken to evaluate anticonvulsant effect of riluzole alone and in combination with sodium valproate on pentylenetetrazole (Metrazol) induced seizures in swiss-albino rats.Methods: Pentylenetetrazole (PTZ) 50 mg/kg intraperitonially (ip) was used to induce seizure in swiss- albino rats. Anticonvulsant effect of riluzole (at 5 mg/kg and 10 mg/kg) and sodium valproate (at 75 mg/kg, 150 mg/kg and 300 mg/kg) was studied on PTZ induced seizures in albino rats. Also effect of riluzole (10mg/kg) in combination with sodium valproate (75 mg/kg, 150 mg/kg and 300 mg/kg) was studied.  Parameters such as time of onset of first clonic convulsion in seconds, frequency of clonic convulsion in 60 minute and total duration of entire convulsion in minutes were studied. For statistical analysis unpaired t test was used.Results: At 5 mg/kg and 10 mg/kg doses riluzole per se was not found to produce any significant effect in PTZ induced seizures (P>0.05). Sodium valproate at 300 mg/kg dose was found to produce significant antiepileptic effect (P0.05). Interestingly significant antiepileptic effect was noted with combination of riluzole (at 10 mg/kg) with sodium valproate at 150 mg/kg and 300 mg/kg dose (P<0.001).Conclusions: Riluzole alone was not found to produce any significant protective effect against PTZ induced seizures in albino rats. However riluzole (10 mg/kg) was found to enhance the antiepileptic activity of sodium valproate

Role Based Secure Data Access Control for Cost Optimized Cloud Storage Using Data Fragmentation While Maintaining Data Confidentiality

The paper proposes a role-based secure data access control framework for cost-optimized cloud storage, addressing the challenge of maintaining data security, privacy, integrity, and availability at lower cost. The proposed framework incorporates a secure authenticity scheme to protect data during storage or transfer over the cloud. The framework leverages storage cost optimization by compressing high-resolution images and fragmenting them into multiple encrypted chunks using the owner's private key. The proposed approach offers two layers of security, ensuring that only authorized users can decrypt and reconstruct data into its original format. The implementation results depicts that the proposed scheme outperforms existing systems in various aspects, making it a reliable solution for cloud service providers to enhance data security while reducing storage costs

KvLQT1 and KCNE1 K+ channel gene polymorphisms in long QT syndrome

Long QT Syndrome (LQTS), a disorder of the cardiac repolarization process with prolongation of the QT interval (QTc &#8805;0.46 seconds), is an ion-channelopathy. Mutations in either KCNQ1 or KCNE1 genes are susceptible to LQTS. Hence, screening of KCNQ1 and KCNE1 genes is taken up to evaluate the genetic correlation of these genes in Long QT patients of Indian origin. A total of 33 Long QT Syndrome patients and 100 healthy subjects were enrolled for the present study. PCR-SSCP protocol was utilised for screening of KCNQ1 and KCNE1 genes followed by In-silico and statistical analysis. The clinical profile of the Long QT syndrome patients in our study revealed a higher percentage of females with the mean age also being higher in females when compared to males. The two variations (S546S and IVS13+36A&#62;G) in KCNQ1 and the S38G polymorphism in KCNE1 gene were identified and their association with Long QT syndrome is being reported for the first time in Indian population. S546S is located in the KCNQ1 C terminus close to this domain and IVS13+36A&#62;G is located in the intronic region in close proximity to the coding region for C-terminal domain; these may therefore affect the functional protein through non-assembly. S38G leads to a substitution of serine to glycine at 38th amino acid position (S38G) in the transmembrane domain of KCNE1. Our study reports compound heterozygosity/genetic compound ofS546S and IVS13+36A&#62;G of KCNQ1 gene. Haplotype frequencies and linkage disequilibrium analysis revealed a significant association between the three biomarkers. Compound heterozygosity of the polymorphisms influence downstream signalling and KCNQ1-KCNE1 interactions