Transverse Crack Initiation and Propagation in Unidirectional Composites with Manufacturing Defects

The objective of the current work is to study damage initiation and propagation in unidirectional fiber-reinforced polymeric composites under transverse loading. In the study conducted, a systematic analysis is carried out to analyze the effects of manufacturing induced defects such as random distribution of fibers and presence of voids in matrix on the damage initiation in unidirectional composites under transverse tension. As illustration, this study focuses on the resin infusion manufacturing process and the defects hence formed. Upon infusing resin, the initial fiber configuration undergoes perturbation and results in a random distribution with regions of resin rich areas and fiber clusters. In addition, micro voids (between the fibers in a bundle) and macro voids (between fiber bundles) are usually formed from the manufacturing process. Effort is laid on quantifying the effect of manufacturing defects to the failure events. Representative Volume Elements (RVEs) are constructed to capture essential features of the composite microstructure that determine the local stress fields and hence damage initiation followed by further events of damage. Stress analysis of the RVEs is conducted using Abaqus FEA software. A novel methodology is put forward to generate random distributions of fibers that would simulate different levels of perturbations of the fibers from initial (dry bundle) positions during the manufacturing process resulting in different configurations of fiber clusters. An embedded RVE approach has been adopted in a finite element model to calculate the stress fields to avoid artificial effects of the RVE boundary. Damage initiation is then monitored using a previously proposed energy based criterion for cavitation induced fiber/matrix debonding in polymers. The first event of failure is determined by the energy based criterion. This work also throws light on the significance of energy based failure initiation in polymeric composites. The local stress field determines the first failure event out of the two competing mechanisms- dilatation driven and distortional driven. Subsequent events of damage in the form of crack formation by coalescence of the debond cracks is also analyzed by the energy based approach. The cavitation based damage initiates in the matrix region close to the fiber matrix interface and results in debond formation. These debonds coalesce to form cracks of different length based on the number of fibers debonding. The energy released during the crack growth is monitored for increasing crack length and the criticality is compared to homogeneous case at different crack lengths. The strains at cracking are monitored for varying radial mobility. The effect of non-uniformity in fiber distribution is gauged by comparing the total J Integral of the RVEs with homogeneous and matrix medium. Ongoing and future work is aimed at studying ply cracking process to its full extent and its consequence on crack deflection into inter-ply regions leading to delamination

Study of Surface Morphology and Microstructure of Electrodeposited Polycrystalline Cu Films

The applications of polycrystalline films range from interconnects in the electronics and semiconductor industry to solar cells and as corrosion protection. Despite their significance, factors that determine their microstructure and morphology remain largely unsolved. The surface and microstructure of electrodeposited polycrystalline Cu films were investigated. This involves looking at the later growth stages of Cu films using different surface and bulk characterization techniques. The surface evolution of an electrodeposited Cu film was imaged in real-time using a Highspeed Atomic Force Microscope (HS-AFM). This provides details about how the film structure coarsens with time. The high-resolution video showed accelerated local grain growth and grain overgrowth at different locations of the film. A combination of both of these mechanisms could drive structural coarsening. The microstructure could play a role in inducing faster growth in certain grains. How the local and large-scale roughness varies with film thickness is studied by scaling analysis. As a complement to scaling analysis, variation in the local slope with thickness is calculated using slope analysis. Rapid growth was observed in the regions where the HS-AFM tip was scanning. The removal of oxygen adlayer from the surface by the tip could promote faster growth in these regions. Pulsed electrodeposition produced Cu films with hexagonal structures. They are known to be twinned which is a desirable feature in applications that require superior mechanical and electrical properties. The effect of electrode potential on grain size was studied. Using a watershed segmentation algorithm, the grain area was calculated from the AFM images. The grain area showed an increasing trend with increasing overpotential. Slope analysis on the ’hexagons’ and the complete films electrodeposited at higher potential revealed higher slopes and distinct slope distribution. Cross-sectional Focused Ion Beam (FIB) milling confirmed that horizontal twins are present in the pulse-deposited Cu films. The hexagonal pyramids with twins could be produced by one of the two mechanisms, stress relaxation during the ’OFF’ period of pulsing or driven by screw dislocation. We attribute the origin of the hexagons to spiralling screw dislocations. A template matching algorithm was developed to try and correlate the surface and microstructural data of a Cu film grown on a microelectrode. It involved matching the AFM and Electron Back Scatter Diffraction (EBSD) data on the later FIB milled sample, thus relating surface topography to crystallographic orientation. The crystallographic orientation of the edge of the microelectrode and its centre showed different orientations, switching from (111) to (110). Twinning was investigated at the edge and the centre of the microelectrode revealing the presence of stacking fault twins in both of these regions

A COMPREHENSIVE UNDERSTANDING OF MAJJAVAHA SROTODUSHTI NIDANA

The concept of Srotas has explained diligently by our Acharyas to understand the functioning of our body. Charaka brings out the terms like Sira, Dhamani, Srotas under one heading and defines these are the structures which are Avakashayukta and carry the bodily elements and if they are intact and functioning properly, the body will be free from diseases. Hence we can say Srotas is a broad term which is essential for transportation of vital elements of the body. Srotas are innumerable in number as there are innumerable number of Bhava in the body and the concept of Srotomaya Purusha is told. The things which are carried through the Srotas will undergo transformation as it reaches its destination. Srotas are classified for our basic understanding into Bahya (Sthula) and Abhyantara (Sukshma). While explaining the Abhyantara srotas, Charaka has enumerated Majjavahasrotas, its Dushti nidana and Lakshana. Susrutha on the other hand has not included Majjavaha srotas and he has not described a structure to carry Majja in the body, rather he believed Majja is the entity present inside the Asthi. Majja is always proved to be controversial as the term Masthishka Majja/Mastulunga is a coined term along. This paper will explain about the conceptual understanding of Majjavaha Srotodushti Nidana and a precise understanding of Majja and Mastulunga.

ASSESSMENT OF ANTIOXIDANT POTENTIAL AND ANTIGENOTOXICITY ANALYSIS THROUGH HYDROGEN PEROXIDE-INDUCED OXIDATIVE STRESS IN TERMINALIA PANICULATA ROTH

Objective: The present study is mainly focused on the antigenotoxicity and antioxidant potential of the fruit extract of an important dye yielding plant Terminalia paniculata Roth. Methods: Genoprotective activity of the fruit extract was studied by Allium cepa root tip assay. Three modes of treatment were used to perform the antigenotoxicity, that is, pre-treatment, post-treatment, and simultaneous treatment. For the study of antioxidant potential, four different assays were performed. Results: Antigenotoxicity studies revealed the protective role of the extract in chromosomal aberrations induced by 2% hydrogen peroxide (H2O2) on A. cepa root tip meristem. The fruit extract showed a significant modulatory effect by means of an inhibition percentage and also it showed a characteristic reversing of chromosomal aberrations induced by H2O2. While in the case of antioxidant activity, the plant extract showed an appreciable antioxidant potential. Four different assays were used to determine the antioxidant potential of T. paniculata. Of these 2,2-diphenyl-1-picryl-hydrazyl-hydrate radical scavenging activity revealed almost equal effect to that of the standard. Conclusions: In the present investigation, it has been found that the important dye yielding plant T. paniculata has a significant role in various commercial industries such as food, cosmetics, clothes, and pharmaceutics due to its efficient protective role

From PeV to TeV: Astrophysical Neutrinos with Contained Vertices in 10 years of IceCube Data

The IceCube Neutrino Observatory is a cubic-kilometer Cherenkov detector at the South Pole, designed to study neutrinos of astrophysical origin. We present an analysis of the Medium Energy Starting Events (MESE) sample, a veto-based event selection that selects neutrinos and efficiently rejects a background of cosmic ray-induced muons This is an extension of the High Energy Starting Event (HESE) analysis, which established the existence of high-energy neutrinos of astrophysical origin. The HESE sample is consistent with a single power law spectrum with best-fit index $2.87^{+0.20}_{-0.19}$, which is softer than complementary IceCube measurements of the astrophysical neutrino spectrum. While HESE is sensitive to neutrinos above 60 TeV, MESE improves the sensitivity to lower energies, down to 1 TeV. In this analysis we use an improved understanding of atmospheric backgrounds in the astrophysical neutrino sample via more accurate modeling of the detector self-veto. A previous measurement with a 2-year MESE dataset had indicated the presence of a possible 30 TeV excess. With 10 years of data, we have a larger sample size to investigate this excess. We will use this event selection to measure the cosmic neutrino energy spectrum over a wide energy range. The flavor ratio of astrophysical neutrinos will also be discussed.Comment: Presented at the 38th International Cosmic Ray Conference (ICRC2023). See arXiv:2307.13047 for all IceCube contribution

DETERMINATION OF ENERGY CONTENT, PHYTOCHEMICAL CONSTITUENTS AND ANTIOXIDANT ACTIVITY OF POTENTIAL WILD EDIBLE LEGUME; CANAVALIA ROSEA (SW.) DC. FROM NORTHERN KERALA

Objective: Major objective of this study is to determine the calorific value and antioxidant activity of Canavaliarosea. Methods: Petroleum ether extract of the seeds were tested qualitatively for twelve components. Calorific value in kJ/100g seed flour was determined based on the results of the proximate analysis. Enzymatic and non-enzymatic antioxidants were analyzed by standard procedures using UV-Visible Spectrophotometer. Results: C. roseais a perennial creeper with roughly circular compound leaves. Flowers are brightly pink-purple, in racemes. It is having large fruits up to 8-12 cm, with brown dormant seeds inside. Seeds were collected from banks of ‘Kabani’ River (Panamaram) and from various tribal hamlets in Wayanad district, Kerela. Preliminary phytochemical screening reveals the presence of eight compounds such as, tannins,saponins, flavonoids, cardiac glycosides, terpenoids, phenols, coumarins and phlobatannins. The analysis of nutritive value of seed has a higher value of crude protein (48.71 %) and crude carbohydrate (34.07). The calorific value of seed material was 1529.9kJ/100g seed flour. Enzymatic antioxidants superoxide dismutase (38.134 u/mg fw) and catalase (19.051 u/mg dw) then non-enzymatic antioxidants poly phenols (12.81 u/mg dw) and ascorbic acid (10.301 u/mg fw) were tested. All those tests show significant levels of antioxidants in the sample. Conclusion: Hence, the present study providing details about the place of collection, ethnobotanical information, energy content and antioxidant activity of Canavaliarosea

Modulating Thin Film Transistor Characteristics by Texturing the Gate Metal.

The development of reliable, high performance integrated circuits based on thin film transistors (TFTs) is of interest for the development of flexible electronic circuits. In this work we illustrate the modulation of TFT transconductance via the texturing of the gate metal created by the addition of a conductive pattern on top of a planar gate. Texturing results in the semiconductor-insulator interface acquiring a non-planar geometry with local variations in the radius of curvature. This influences various TFT parameters such as the subthreshold slope, gate voltage at the onset of conduction, contact resistance and gate capacitance. Specific studies are performed on textures based on periodic striations oriented along different directions. Textured TFTs showed upto ±40% variation in transconductance depending on the texture orientation as compared to conventional planar gate TFTs. Analytical models are developed and compared with experiments. Gain boosting in common source amplifiers based on textured TFTs as compared to conventional TFTs is demonstrated

Dynamic analysis of serum Ca-125 levels during neoadjuvant chemotherapy in patients with advanced epithelial ovarian cancer: a retrospective study

Background: Assessment of CA-125 kinetics was commonly used as a tool for tumor response to chemotherapy in ovarian cancer patients. The study aimed to determine any logarithmic/linear relationship between pre-chemotherapy and pre-operative CA-125 levels in ovarian cancer.Methods: Total 52 patients who underwent neoadjuvant chemotherapy (NACT) followed by interval cytoreductive surgery were included. CA-125 levels before starting chemotherapy, during chemotherapy and the preoperative value, with the date of measurement recorded. Cox’s proportional hazards regression was used to evaluate univariate and independent multivariable association with the effect of clinical, pathological and CA-125 kinetic parameters on outcome endpoints.  Results: The study couldn’t establish any relationship in logarithmic fall of CA-125 values among ovarian cancers as a result of neo-adjuvant chemotherapy. The disease-free survival among the patients was 12.2 months.Conclusions: There is an inverse relationship between serum CA-125 levels and survival in ovarian cancer. NACT resulted in adequate fall of CA-125 levels in most of the patients, but the rate of fall was not predictive of prognosis

Ayurvedic Management of Ardita - A Case Report

Ardita is a condition that developes due to excessive aggravation of Vata and causes distortion of face. Facial palsy the paralysis of facial nerve also affects the movement of facial muscles and shows similar symptoms. So we can almost correlate these diseases. Allopathic management of facial palsy includes the use of steroids and some anti-inflammatory drugs only, with a chance of recurrence and side effects. Present study reveals that Ardita can be managed successfully with ayurvedic treatments with lesser chance of recurrence and without any side effects