Assessment of the toughness of fibre-reinforced concrete using the R-curve approach

The fracture response of brittle materials like concrete can be characterised using modified linear elastic fracture mechanics models, such as the rising resistance curve (R-curve). In this study, the R-curve, determined by utilising the experimental response in the notched beam test with mode I fracture, is proposed as a measure of the toughness of fibre-reinforced concretes (FRCs). The unambiguity of the R-curve obtained is assessed by comparing the predicted flexural response of specimens of different geometries with experimental data. The variation in the R-curves with the dosage of steel and polymer fibres is also discussed.     

Locked nucleic acids and intercalating nucleic acids in the design of easily denaturing nucleic acids: thermal stability studies

Intercalating nucleic acids (INA(R)s) with insertions of (R)-1-O-(1-pyrenylmethyl)glycerol were hybridized with locked nucleic acids (LNAs). INA/LNA duplexes were found to be less stable than the corresponding DNA/LNA duplexes when the INA monomer was inserted as a bulge close to the LNA monomers in the opposite strand. This property was used to make "quenched" complements that possess LNA in hairpins and in duplexes and are consequently more accessible for targeting native DNA. The duplex between a fully modified 13-mer LNA sequence and a complementary INA with six pyrene residues inserted after every second base as a bulge was found to be very unstable (Tm=30.1 degrees C) in comparison with the unmodified double-stranded DNA (Tm=48.7 degrees C) and the corresponding duplexes of LNA/DNA (Tm=81.6 degrees C) and INA/DNA (Tm=66.4 degrees C). A thermal melting experiment of a mixture of an LNA hairpin, with five LNA nucleotides in the stem, and its complementary DNA sequence gave a transition with an extremely low increase in optical density (hyperchromicity). When two INA monomers were inserted into the stem of the LNA hairpin, the same experiment resulted in a significant hyperchromicity comparable with the one obtained for the corresponding DNA/DNA duplex.     

Analysis of direct immobilized recombinant protein G on a gold surface

For the immobilization of IgG, various techniques such as chemical linker, thiolated protein G methods, and fragmentation of antibodies have been reported [Y.M. Bae, B.K. Oh, W. Lee, W.H. Lee, J.W. Choi, Biosensors Bioelectron. 21 (2005) 103; W. Lee, B.K. Oh, W.H. Lee, J.W. Choi, Colloids Surf. B-Biointerfaces, 40 (2005) 143; A.A. Karyakin, G.V. Presnova, M.Y. Rubtsova, A.M. Egorov, Anal. Chem. 72 (2000) 3805]. Here, we modified the immunoglobulin Fc-binding B-domain of protein G to contain two cysteine residues at its C-terminus by a genetic engineering technique. The resulting recombinant protein, RPGcys, retained IgG-binding activity in the same manner as native protein G. RPGcys was immobilized on a gold surface by strong affinity between thiol of cysteine and gold. The orientations of both IgG layers immobilized on the base recombinant protein Gs were analyzed by fluorescence microscope, atomic force microscope (AFM), and surface plasmon resonance (SPR). Our data revealed that IgG-binding activity of RPGcys on gold surface significantly increased in comparison to wild type of protein G (RPGwild), which was physically adsorbed due to absence of cysteine residue. Immobilization of highly oriented antibodies based on cysteine-modified protein G could be useful for the fabrication of immunosensor systems.     

Influence of Syzygium cumini leaves extract on morphological,thermal, mechanical,and antimicrobial properties of PVA and PVA/chitosan blend films

In the present work, poly(vinyl alcohol)/Syzygium cumini leaves extract (PSN) and poly(vinyl alcohol)/chitosan/S. cumini leaves extract blend films were prepared by solution casting technique. The films were characterized by using scanning electron microscopy, atomic force microscopy, X‐ray diffraction study, Fourier transform infrared spectroscopy, thermogravimetric analysis, and universal testing machine. The results indicated that the appreciable physical interaction at lower concentrations of S. cumini leaves extract in the PVA and PVA/chitosan films contribute to the smooth uniform morphology, increased the degree of crystallinity, degradation temperature, and improved mechanical properties. Further, films were analyzed with water contact angle analyzer which illustrates that blend films were hydrophilic (PSN‐1) and hydrophobic (PCS‐1) in nature. However, blend films were also subjected to the antimicrobial study, which revealed that inclusion of S. cumini leaves extracts significantly enhanced the antibacterial activity in the PVA and PVA/chitosan film. With all of these results, fabricated blends can find potential applications in packaging material to extend the shelf life of foodstuffs. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46188.     

Biocompatible tumor micro-environment responsive CS-g-PNIPAAm co-polymeric nanoparticles for targeted Oxaliplatin delivery

The objective of the research study was to develop and characterize a biodegradable, thermo and pH dual responsive Oxaliplatin-loaded chitosan-graft-poly-N-isopropylacrylamide (CS-g-PNIPAAm) co-polymeric nanoparticles as a tumor-targeting drug delivery system. CS-g-PNIPAAm co-polymers were synthesized, characterized and optimized its thermo and pH responsive properties for tumor microenvironment conditions. Optimized co-polymer could be efficiently loaded with Oxaliplatin in nanoparticle form, evaluated for their morphology (TEM), particle size, zeta potential, loading efficiency and drug content. In vitro drug release study at tumor microenvironment and physiological pH and temperature conditions. The in vitro drug release was optimal at above lower critical solution temperature (LCST) and tumor microenvironment pH when compared to physiological pH & temperature. MTT assay and fluorescence microscopic study showed that drug release and cell uptake was significantly enhanced in tumor microenvironment. In conclusion, the obtained nanoparticles appeared to be of great promise in tumor targeted drug delivery of oxaliplatin.     

The stability of bovine parvovirus and its possible use as an indicator for the persistence of enteric viruses

Bovine parvovirus 1 (Haden virus) gives with grown in 0–24 h secondary cultures of calf kidney a pronounced CPE. The virus is very thermoresistant, it takes e.g. at 60°C 6 h to decrease the titer of infectivity 1 log unit.When seeded in liquid manure the virus becomes inactivated at a rate of around 6–8 days for 1 log unit under aerobic conditions at 5–20°C. The inactivation under anaerobic conditions is very temperature dependent: at 5°C it takes about 200 days to decrease the titer 1 log unit, but at 20°C a rate of inactivation of 20 days per log unit of virus was found.It is suggested that the bovine parvoviruses may be useful as indicators in connection with evaluations of the importance of viral bovine faecal pollution. For evaluations of treatment efficiencies it is suggested that these parvoviruses may also be used as indicators for human enteric viruses like the virus of infectious hepatitis.     

Platinum group elements in the environment and their health risk

Accumulation of platinum group elements (PGEs) in the environment has been increased over the time. Catalytic converters of modern vehicles are considered to be the main sources of PGE pollution, since the correlation is between the Pt:Rh ratios in various environmental compartments and in converter units. The present literature survey shows that the concentration of these metals has increased significantly in the last decades in diverse environmental matrices; like airborne particulate matter, soil, roadside dust and vegetation, river, coastal and oceanic environment. Generally, PGEs are referred to behave in an inert manner and to be immobile. However, there is an evidence of spread and bioaccumulation of these elements in the environment. Platinum content of road dusts can be soluble, consequently, it enters the waters, sediments, soil and finally, the food chain. The effect of chronic occupational exposure to Pt compounds is well-documented, and certain Pt species are known to exhibit allergenic potential. However, the toxicity of biologically available anthropogenic Pt is not clear. Hence, there is a need to study the effect on human health of long-term chronic exposure to low levels of Pt compounds.     

Optimal Design of Pressurized Irrigation Subunit

A linear programming (LP) model is presented for optimal design of the pressurized irrigation system subunit. The objective function of the LP is to minimize the equivalent annual fixed cost of pipe network of the irrigation system and its annual operating energy cost. The hydraulic characteristics in the irrigation subunit are ensured by using the length, energy conservation, and pressure head constraints. The input data are the system layout, segment-wise cost and hydraulic gradients in all the alternative pipe diameters, and energy cost per unit head of pumping water through the pipeline network. The output data are: segment-wise lengths of different diameters, operating inlet pressure head, and equivalent annual cost of the pipeline network. The explicit optimal design is demonstrated with design examples on lateral and submain or manifold of pressurized irrigation systems. The effect of the equations for friction head loss calculation on optimization procedure is investigated through the design example for microirrigation manifold. The performance evaluation of the proposed model in comparison with the analytical methods, graphical methods, numerical solutions, and dynamic programming optimization model reveals the good performance of the proposed model. The verification of operating inlet pressure head obtained by the proposed model with accurate numerical step-by-step method suggested that it is mostly accurate.     

Formation of oligosaccharides in skim milk fermented with mixed dahi cultures, Lactococcus lactis ssp diacetylactis and probiotic strains of lactobacilli

Milk fermented with mixed dahi cultures NCDC167, Lactococcus lactis ssp diacetylactis NCDC60 and two probiotic strains; Lactobacillus acidophilus NCDC14 and Lb. casei NCDC19 were evaluated after fermentation (14 h) and during 8 d storage at 7 degrees C. The beta-galactosidase activity was found to increase after fermentation leading to the hydrolysis of lactose and production of glucose, galactose and oligosaccharides; that subsequently decreased during storage. The viable counts of lactococci and lactobacilli decreased during storage yet remained >106 cfu/ml after storage. The results of present study indicate that all the selected cultures have ability to produce oligosaccharides (prebiotics) due to transgalactosidal and lactose hydrolysis activities of beta-galactosidase. The cultures developed an active synbiotic formula by maintaining sufficient probiotic viable counts to exert health benefits to the consumers.