IN VITRO STUDY ON RELEASE OF BIOACTIVE ANTIMICROBIAL COMPOUNDS FROM DAIRY PRODUCTS BY CERTAIN PROMISING PROBIOTIC LACTOBACILLUS STRAINS

Objective: The antimicrobial activity and Probiotic properties of Lactobacillus species were evaluated. The antimicrobial compound of potent antimicrobial probiotic Lactobacillus was purified by column chromatography and its nature and stability were determined.Methods: This investigation was performed with few Lactobacillus strains of ATCC and MTCC along with certain strains isolated from different dairy sources. They were evaluated for their probiotics properties (acid tolerance, bile tolerance, bile salt hydrolase activity, cell autoaggregation, cell surface hydrophobicity and haemolytic behaviour). Agar well diffusion method was used to screen their potency to release bioactive compound against several pathogens. This potent antimicrobial compound was purified by chromatography as well as its molecular mass was estimated by following SDS-PAGE. Finally, the stability of the compound was determined against various ranges of temperature and pH.Results: Among all Lactobacillus strains, R1 was found to be a potent probiotic strain as well as cell free supernatant (CFS) of R1 showed more strong antagonistic effect against most of the pathogens. Carbohydrate fermentation and physiological characterization of strain R1 matched with Lactobacillus fermentum as per Bergey's manual of systematic bacteriology. The molecular mass of the purified fraction was estimated at approximately 25 kDa and could be stable after heat treatment of 100 °C for 30 min and pH range of 4.5-7.0Conclusion: R1 showed highest antimicrobial activity while it has been found as Lactobacillus fermentum. It is due to the release of a bioactive compound having a molecular mass of 25 kDa.Â

Surface stress in metals induced by organic monolayer films

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Environment-assisted fracture, my friend: The cutting of gummy metals

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Areca Palm Sheath: A Plant-Based Material Alternative to Plastics for Foodware Products

The proliferation of single-use plastics in the foodware and packaging sector has stimulated interest in sustainable material substitutes that can be processed efficiently and which possess sufficient structural integrity. Herein, we study the structure, mechanical response and diffusion properties of leaf-sheath from a representative palm species—Areca catechu—widely cultivated in the Indian sub-continent and Southeast Asia. The study of this material system, and the specific attributes, are motivated by the use of this material in foodware applications. Foodware such as plates and bowls can be produced from the areca sheath, directly, in a single step, by stretch forming analogous to sheet metals. The material is eco-friendly, biodegrading in ~100 days. Formability and water diffusion are two key attributes of relevance for foodware, since the former attribute determines the shape change capability of the material and range of producible shapes; and the latter, foodware product (structural) integrity and life. We characterize the morphology (external structure) and anatomy (internal structure) of the sheath using imaging techniques and composition analysis. The sheath is shown to resemble a composite material, with structural characteristics intermediate between those of the palm leaf and stem. By measuring the mechanical response of the sheath to various types of 1D and 2D loading (e.g., uniaxial tension and compression, biaxial stretching, rolling), and hydration conditions, we show that the sheath material has high stretch-formability, especially when hydrated. This formability is similar to that of the most ductile sheet metals. The formability is shown to be further enhanced by addition ofsmall quantities of NaOH (~5%) during hydration. Local deformation measurements in biaxial stretching, based on analysis of distortion of grid-markers inscribed onto sheath samples, have enabled characterization of strain-field anisotropy and mode of failure in the sheath. By consolidating the mechanical test results, we present a forming limit diagram for the leaf-sheath. The structural integrity and life of foodware products produced from the leaf-sheath are directly determined by diffusion of liquids (e.g., water, oils) through the sheath wall thickness. Water and oils are important constituents of semi-solid and solid foods. Diffusion of water is also important for designing the hydration cycle to enhance formability. The diffusion of water through the sheath material process is studied using mass gain measurements and in situimaging of water transport. We determine the diffusion coefficient for water, which is critical for estimating product life. The diffusion coefficient for the matrix is shown to be one order of magnitude greater than for the fiber. We vary salt concentration in the water by controlled additions of NaCl and note a non-monotonic dependence of the diffusion on concentration. By subjecting the leaf-sheath to a short-time (~ 3 minutes) thermal treatment (~ 800 C), a hydrophobic wax layer can be made to secrete onto the leaf surface. This wax coating is found to significantly reduce the water diffusion, enabling the sheath foodware life to be increased. Lastly, we argue, that since the leaf-sheath is a “waste product” of the palm, it has negligible embodied energy (4 to 5 orders of magnitude smaller) compared to paper and plastics based foodware. We discuss the implications of the results for single-step forming of high-aspect ratio products and structures from the palm sheath, methods to reduce diffusion of liquids and improve foodware product life, and some directions for future research into mechanical behavior of plant leaf materials from a forming perspective

EVALUATION OF PROBIOTIC AND ANTIMICROBIAL PROPERTIES OF LACTOBACILLUS STRAINS ISOLATED FROM DAIRY PRODUCTS

Objective: Evaluation of antimicrobial efficacy of probiotic Lactobacillus strains isolated from dairy products.Methods: The study used yogurt sample prepared from raw buffalo milk to isolate Lactobacillus strains by following pour plate technique. All isolated Lactobacillus strains were systematically screened for their probiotic attributes. Here, functional criteria studies for successful probiotics mainly included survival ability of the strains. The capability of the selected Lactobacillus isolates to inhibit the growth of several pathogens was evaluated by the well diffusion method. Based on phenotypic characteristics, biochemical tests and of 16S rDNA sequence analysis, the potent probiotic strain was identified. Further study was emphasized on its optimum parameters required for its growth. Again, its activity was characterized with respect to pH, NaCl and thermal stability along with susceptibility to enzymes. Results: A preliminary subtractive screening based on antimicrobial potency and probiotic properties revealed the maximum effectiveness of Lactobacillus DM 69 among all and it was identified as Lactobacillus plantarum. The inhibitory substance obtained from DM 69 was relatively heat stable and active under acidic conditions. No susceptibility was found in the presence of α-amylase, lipase and lysozyme.Conclusion: Excellent probiotic and an antimicrobial strain was isolated from buffalo milk and can be formulated and developed as a good nutraceutical food supplement

High temperature indentation based property measurements of IN-617

Inconel 617 (IN-617) mainly contains nickel (Ni), chromium (Cr), cobalt (Co) and molybdenum (Mo). IN-617 is widely used in applications that require high temperature operation due to its high temperature stability and strength as well as its strong resistance to oxidation and carburization. The current work focuses on the measurement of temperature dependent mechanical properties of IN-617 from room temperature (around 25 °C) up to 800 °C. The properties measured are reduced modulus, elastic modulus, hardness, indentation creep rate, indentation creep exponent, and thermal activation volume. The indentation size effect is analyzed as a function of temperature. Using a combination of optical microscopy and scanning electron microscopy (SEM) imaging, the effect of precipitate distribution and oxidation on the measured properties is found to be negligible beyond a critical indentation depth. The mean hardness value ranged from 3.1 GPa at room temperature to 1.6 GPa at 800 °C. A relation between indentation depth and hardness as a function of temperature change was used to extract strain gradient plasticity associated length scales with values changing from 1.0 μm at room temperature to 1.8 μm at 400 °C and to 1.6 μm at 800 °C

Diagnostic accuracy of Leucine-rich α-2 glycoprotein (LRG) as a urinary biomarker in pediatric appendicitis: a prospective observational pilot study from Eastern India

Abstract Background Recently, several serum and urinary biomarkers have been investigated for diagnosis of acute appendicitis. Urinary biomarkers seem to be advantageous in children as it is non-invasive, painless, and easy to perform. Leucine-rich α-2-glycoprotein (LRG) is regarded as a reliable urinary biomarker for the diagnosis of pediatric appendicitis. A prospective observational pilot study was conducted in children presenting with abdominal pain. Assessment of pediatric appendicitis score (PAS), routine blood tests, and measurements of urinary LRG was done. The present study aimed to evaluate the diagnostic accuracy of urine LRG in appendicitis in Indian children and to assess the concentration of urine LRG at which it will guide the management. Results LRG had a receiver operating characteristic (ROC) area under the curve (AUC) of 0.586 (95% CI 0.407–0.766). There was no specific cut-off identified using Youden’s index. ROC analysis of the PAS score resulted in an AUC of 0.821 (95% CI 0.691–0.952). Using Youden’s index, the cut-off for PAS scoring was identified as 6.5 with the sensitivity of 80%, the specificity of 76.2%, positive predictive value 76.19%, negative predictive value as 80%, and diagnostic accuracy of 78%. Conclusions LRG could not show better diagnostic performance compared to routine blood tests and PAS scores. There was no specific cut-off value at which it will differentiate mesenteric adenitis and acute appendicitis and guide their management. With 78% diagnostic accuracy, PAS score (> 6) is still a better tool for the diagnosis of acute appendicitis. Trial registration Clinical Trials Registry Government of India,  CTRI/2018/01/011182 , Registered on: 08 Jan 2018