A New Methodology for Recognition of Milling Features from STEP File

In recent years, various researchers have come up with different ways and means to integrate CAD and CAM. Automatic feature recognition (AFR) from a CAD solid model for down stream applications like process planning and NC program, greatly contribute to the level of integration. When generating G&M codes from CAD DXF file, it leads to the loss of geometric information and the user is to edit and fills the details of the lost data. STEP is an international standard for geometric and non geometric data transfer between CAD, CAE and CAM and it replaces the IGES and DXF. For that reason this paper proposes an automatic feature recognition methodology to develop a feature recognition system using STEP file. The proposed methodology is developed for 3D prismatic parts that are modeled any CAD software having STEP output file format. A JAVA program is used to implement the geometric data extraction algorithm, which has been developed for extracting the geometric information from the STEP file. A feature recognition algorithm is used to recognize the different features of the part such as slot, pocket etc based on geometric reasoning approach by taking B-rep data base as input. The authors present an example to demonstrate the application of the proposed methodology

Synthesis and Characterization of PLA/Luffa Cylindrica Composite Films

In recent days, natural fibers have been replaced with synthetic fibers as an alternative material for the reinforcement in the polymer composites due to their renewability and sustainability. The aim of the present work is to study the performance of using natural fiber powder in the preparation of composite films. The fiber powder used in the present study is extracted from the Luffa cylindrica plant. Fourier Transform Infrared (FTIR) spectrum is utilized for the identification of functional groups in the fabricated composite film. Scanning Electron Microscopy (SEM) analysis is carried out to observe the bonding between matrix and reinforcement in the composite films. Thermal degradation behaviour of the composite film is also studied by the Thermo-gravimetric Analysis (TGA). From the studies, it was observed that the natural fiber reinforced composite film were able to withstand higher temperatures. The fabricated composites films can be effectively used for different applications where there is a necessity of bio polymers

Response of cardamom (Elettaria cardamomum Maton) seedlings to vesicular arbuscular mycorrhizal fungi

The growth response of cardamom (Elettaria cardamomum) seedlings (cv, Malabar) to 13 different vesicular arbuscular mycorrhizal fungi was tested under mat house conditions at Bangalore, India, In general, seedlings inoulated with the fungi grew taller, had more number of leaves and tillers, increased seedling biomass and uptake of nutrients compared to control seedlings, Among the various mycorrhizal fungi tested, seedlings inoculated with Gigaspora margarita and Glomus monosporum exhibited significantly higher growth with increased uptake of nutrients, &nbsp

Response of cardamom (Elettaria cardamomum Maton) seedlings to vesicular arbuscular mycorrhizal fungi

The growth response of cardamom (Elettaria cardamomum) seedlings (cv, Malabar) to 13 different vesicular arbuscular mycorrhizal fungi was tested under mat house conditions at Bangalore, India, In general, seedlings inoulated with the fungi grew taller, had more number of leaves and tillers, increased seedling biomass and uptake of nutrients compared to control seedlings, Among the various mycorrhizal fungi tested, seedlings inoculated with Gigaspora margarita and Glomus monosporum exhibited significantly higher growth with increased uptake of nutrients, &nbsp

High quality factor 1-D Er 3+ -activated dielectric microcavity fabricated by RF-sputtering

Rare earth-activated 1-D photonic crystals were fabricated by RF-sputtering technique. The cavity is constituted by an Er3+-doped SiO2 active layer inserted between two Bragg reflectors consisting of ten pairs of SiO2/TiO2 layers. Scanning electron microscopy is employed to put in evidence the quality of the sample, the homogeneities of the layers thickness and the good adhesion among them. Near infrared transmittance and variable angle reflectance spectra confirm the presence of a stop band from 1500 nm to 2000 nm with a cavity resonance centered at 1749 nm at 0° and a quality factor of 890. The influence of the cavity on the 4I13/2 -> 4I15/2 emission band of Er3+ ion is also demonstrated

Tryptophan fluorescence quenching as a binding assay to monitor protein conformation changes in the membrane of intact mitochondria

Intrinsic protein fluorescence is due to aromatic amino acids, mainly tryptophan, which can be selectively measured by exciting at 295 nm. Changes in emission spectra of tryptophan are due to the protein conformational transitions, subunit association, ligand binding or denaturation, which affect the local environment surrounding the indole ring. In this study, tryptophan fluorescence was monitored in intact mitochondria at 333 nm following excitation at 295 nm in presence of insecticides using spectrofluorometer. Methyl-parathion, carbofuran, and endosulfan induced Trp fluorescence quenching and release of cytochrome c when incubated with the mitochondria, except fenvalarate. Mechanism of insecticide-induced mitochondrial toxicity for the tested insecticides has been discussed. Reduction in the intensity of tryptophan emission spectra of mitochondrial membrane proteins in presence of an increasing concentration of a ligand can be used to study the interaction of insecticides/drugs with the intact mitochondria. Furthermore, this assay can be readily adapted for studying protein–ligand interactions in intact mitochondria and in other cell organelles extending its implications for pesticide and pharma industry and in drug discovery

A thiazolo[5,4-: D] thiazole-bridged porphyrin organic framework as a promising nonlinear optical material

Porphyrin-based porous organic frameworks are an important group of materials gaining interest due to their structural diversity and distinct opto-electronic properties. However, these materials are seldom explored for nonlinear optical (NLO) applications. In this work, we investigate a thiazolo[5,4-d]thiazole-bridged porous, porphyrin framework (Por-TzTz-POF) with promising NLO properties. The planar TzTz moiety coupled with integrated porphyrin units enables efficient π-conjugation and charge distribution in the Por-TzTz-POF resulting in a high nonlinear absorption coefficient (β = 1100 cm GW-1) with figure of merit (FoM) σ1/σ0 = 5571, in contrast to analogous molecules and material counterparts e.g. metal-organic frameworks (MOFs; β = ∼0.3-0.5 cm GW-1), molecular porphyrins (β = ∼100-400 cm GW-1), graphene (β = 900 cm GW-1), and covalent organic frameworks (Por-COF-HH; β = 1040 cm GW-1 and FoM = 3534). This journal is © The Royal Society of Chemistry

Monitoring biosafety of pharmaceutical drugs, insecticides, and other bioactive molecules to mitochondria

Mitochondria are large cell organelles in plant and animal cells. They convert chemical energy from food in the cell to usable energy using oxygen. This process is called oxidative phosphorylation, which takes place inside the mitochondria. Reactions of Krebs cycle produce a chemical, NADH (Nicotinamide Adenine Dinucleotide, reduced form), which is then used by enzymes present in the inner mitochondrial membrane to generate energy rich adenosine triphosphate (ATP) molecules. These molecules are utilized by the cells whenever energy is required. Therefore, mitochondria are also referred as power houses of the cell. Mitochondria are abundantly present in muscle and brain cells, and sperms to supply ATPs during demand for energy. Monitoring biosafety of pharmaceutical drugs, insecticides, and other bioactive molecules to mitochondria is necessary because some of them interact with the mitochondrial membrane or membrane proteins, thereby affecting the energy levels of cells or even induces mitochondrial-dependent apoptosis (programmed cell death)

Elimination of Gut Microbes with Antibiotics Confers Resistance to Bacillus thuringiensis Toxin Proteins in Helicoverpa armigera (Hubner)

Helicoverpa armigera is one of the most important pests worldwide. Transgenic crops with toxin genes from Bacillus thuringiensis (Bt) have been deployed on a large scale to control this pest. The insecticidal activity of Bt is probably influenced by the insect midgut microbes, which vary across crop hosts and locations. Therefore, we examined the role of gut microbes in pathogenicity of Bt toxins in the H. armigera. Antibiotic cocktail was used for the complete elimination of the H. armigera gut microbes. Activated Cry1Ac, Bt formulation, and transgenic cotton resulted in larval weight loss and increase in mortality, but pretreatment of larvae with antibiotic cocktail significantly decreased larval mortality and increased the larval weight gain. Activated Cry1Ac and Bt formulation inhibited the activity of proteases in midgut of H. armigera larvae but showed no such effect in the larvae pretreated with antibiotic cocktail. Five protease bands in activated Cry1Ac and two in Bt formulation-treated larvae were inhibited but no such effect in the larvae pretreated with antibiotic cocktail. Cry1Ac protein was detected in Bt/Cry1Ac protoxin-fed larval gut extract in the absence of antibiotic cocktail, but fewer in larvae pretreated with antibiotic cocktail. The activity of antioxidant enzymes and aminopeptidases increased in larvae fed on Bt toxin, but there was no significant increase in antioxidant enzymes in larvae reared on toxin protein in combination with antibiotic cocktail. The results suggest that gut microbes exercise a significant influence on the toxicity of Cry1Ac and Bt formulation in H. armigera larvae. The implications of these results have been discussed in relation to development of insect resistance to Bt transgenic crops deployed for pest management

Influence of bacillus thuringiensis toxins on the development and midgut proteases in different larval instars of helicoverpa armigera

Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) is one of the most important pest worldwide. Bacillus thuringiensis (Bt) toxins have used as a biopesticide or deployed in transgenic plants for controlling this pest. We examined the biological activity of Cry1Ac, Cry1Ab and Bt formulation in different larval instars of H. armigera with respect to larval development and proteolytic activity to pinpoint the most susceptible instar, and the insect response to ingestion of Bt toxins. In the presence of Bt toxins, the larval mortality and weight loss increased in a dose-dependent manner, and the maximum effect was observed in neonates. Active Cry1Ac toxin resulted in greater mortality and weight loss in all the larval instars. Total protease, trypsin and chymotrypsin activities declined in the presence of Bt toxins as compared to the untreated control in all the larval instars. Ten protease isozymes were observed in the untreated control larvae in second, third and fourth instars. Maximum protease isozymes inhibition was observed in Bt toxin fed neonates. Inhibition of protease activity increased with the concentration of Bt toxins. In presence of Bt toxins, aminopeptidase activity increased from II to IV instar and alkaline phosphatase activity decreased from II to III and then increased in IV instar. The pathogenicity of Bt was greater in early larval instars of H. armigera than the later instars, suggesting that application of Bt formulation or deployment of Bt toxins in transgenic plants should be directed against the early larval instars