Mutagenicity assessment of Salacia chinensis by bacterial reverse mutation assay using histidine dependent Salmonella typhimurium tester strains

BACKGROUND AND OBJECTIVE: Genotoxicity analysis is one of the most important non-clinical environmental safety investigations required for pharmaceutical and agrochemical product registration. Any medicinal product must undergo a risk evaluation to determine its mutagenicity and carcinogenicity. MATERIALS AND METHODS: The Ames test is a commonly used in vitro test for determining a test chemical\u27s mutagenic activity. Histidine-dependent Salmonella typhimurium strains with a defective gene that causes the bacteria to synthesis the necessary amino acid histidine for life were tested for mutagenic potential. In order to reveal pro-mutagens and mutagens, the mutagenic potential of both plate integration and pre-incubation techniques was examined in the presence and absence of metabolizing system. Salacia chinensis has been widely used in ayurveda to treat various ailments. However, the information of mutagenicity of Salacia chinensis is scarce as per available literature. RESULTS: The mutagenicity of a Salacia chinensis root extract was investigated utilizing the Ames assay with plate incorporation and pre-incubation protocols using the appropriate Salmonella typhimurium tester strains: TA98, TA100, TA1537, TA1535, and TA102 in the presence and absence of S9. The concentrations used were 0.3123, 0.625, 1.25, 2.5 and 5 mg/plate. The extract of Salacia chinensis root did not show any mutagenic effect in any of the Salmonella typhimurium strains at the concentrations tested in the absence or presence of metabolic activation. CONCLUSION: The root of Salacia chinensis was hence confirmed to be non-mutagenic and at least according to the results of this genotoxicity evaluation can be regarded as being safe for human use

Molecular docking studies of natural compounds of naringin on enzymes involved in the urea cycle pathway in hyperammonemia

Purpose: To investigate the anti-hyperammonemic activity of naringin by molecular docking via in silico studies.Methods: Urea cycle proteins were docked to the natural compound naringin as well as a standard drug, sodium benzoate. Hydrogen bonds and binding energy were obtained using Catalytic Site Atlas and Cast P Finder Software Tool.Results: There were six urea cycle enzymes, including N-acetyl glutamate synthase, carbamoyl phosphate synthase I, ornithine transcarbamylase, argininosuccinate synthase, argininosuccinate lyase and arginase I. On evaluating protein interactions with naringin, which is dynamically  connected to the urea cycle pathway with hyperammonemia, naringin showed more hydrogen bonds and also produced higher binding energy when compared to the standard drug, sodium benzoate.Conclusion: The results of the molecular docking study show that naringin interacts with urea cycle enzymes with more hydrogen bonds and higher bonding energy than the standard drug, sodium benzoate. This supports the hypothesis that naringin can prevent experimental hyperammonemia. Keywords: Naringin, Sodium benzoate, Hyperammonemia, Urea cycle enzymes, In silico studies &nbsp

Evaluation of In-Vitro Antioxidant Activity of Biochanin A

This study was aimed to determine the in vitro antioxidant potential of biochanin A (BCA), an isoflavone phytochemical, by using various free radical scavenging assays. The free radical scavenging activity of BCA was evaluated by various standardized assays such as 1, 1-Diphenyl-2-Picryl Hydrazyl (DPPH●), 2, 2’-Azinobis-3-Ethylbenzothiazoline-6-Sulfonic Acid (ABTS●+), Ferric Reducing Antioxidant Power (FRAP),nitric oxide scavenging activity, reducing ability, hydroxy radical activity, superoxide anion scavenging activity, hydrogen peroxide radical, metal ion chelating activity  and phosphomolybdenum  assay. Four different concentrations of BCA (5, 10, 20, 40, μg/ml) were taken for evaluating the scavenging activity and which were compared with the antioxidant activity of standard ascorbic acid (AA). BCA showed good free radical scavenging activity, which was calculated as IC50. IC50 value of BCA was also comparable to Ascorbic acid (AA).Whereas AA was used as a standard. The scavenging activity of BCA was significantly elevated in a dose dependent manner. The BCA was exhibited a highest scavenging activity than the standard. The results obtained in the present study revealed that the BCA is an excellent free radical scavenger with the activity similar to that of AA. Keywords: Biochanin A, Antioxidant, Free radicals, Nitric oxides and Ascorbic aci

Performance of CFS Beam-to-Beam Bolted Connection Using Clip Angle and Flange Strip: Experimental Investigation

This paper presents an experimental investigation on the strength, load versus deflection, and load versus rotation behavior of cold-formed steel (CFS) beam-to-beam connections using a combination of clip angle and flange strip through the use of bolts and self-drilling screws in the webs and flanges, respectively. A total of 24 tests with four different aspect ratios in the loaded leg and three different aspect ratios in the anchored leg for two different clip angle thickness were carried out under four-point bending to study the strength and different failure modes under flexure. The dimension and number of screws in the flange strip connecting the top flanges of the channels to provide restraint against end lateral displacement and rotation at both ends of connection were kept constant. The results indicate that the end rotation depends on the number of bolts in the clip angle connected to the loaded channel and the thickness of the clip angle. A higher degree of stiffness was exhibited by the three-bolt configuration for both thicknesses of the clip angle. The optimum anchored aspect ratio with regard to the strength was found to be 1.0 and 1.5 for the clip angle thicknesses of 0.8 and 1.5 mm, respectively. Three different failure modes were observed in the clip angle: Local buckling, distortional buckling, and bearing in the bolt hole. The ultimate strength increased up to 70% due to the flange strip connection provided at the top of flanges by the application of self-drilling screws. Comparison of the experimental results with literature study indicates the literature approach is ultraconservative in both serviceability and ultimate state. Based on the test results, a new design method was developed for determining the nominal shear strength with consideration of deformation. The load and resistance factor design (LRFD) resistance factor and allowable strength (ASD) safety factor were found to support the modified design equation

Experimental study on beam-to-column clip angle bolted connection

The effectiveness of the clip angle bolted connection between CFS (Cold-formed steel)beam-to-column under shear is investigated in the present study. A total of thirty-one specimens were tested under four-point bending configuration to study the behavior of beam-to-column clip angle connection using bolts. The parameters considered in the experimental study are clip angle thickness and aspect ratio of the clip angle leg connected to the column. The test results indicate that the aspect ratio (L/B)of the clip angle leg plays a significant role in governing the ultimate strength, stiffness and failure mode of the connection. Two different failure modes were observed namely (i)local buckling failure at an aspect ratio (L/B)less than 0.8 and (ii)distortional buckling failure at an aspect ratio (L/B)greater than 0.8 in the clip angle leg connected to the column. An improved design equation for the clip angle bolted connection is proposed and validated with the previous studies from the literature. The proposed design equations for clip angle bolted connection were conservative compared with experimental test results. In addition, a shift in the anchor point (compact limit)i.e., reduction in the slenderness ratio (λ)is suggested for limiting the shear resistance of clip angle bolted connection. Further, reliability studies were carried out to determine the resistance and safety factors for the connections not listed in Table F1 of AISI S100-12 based on the current study and test results from the literature. The suggested design method will be applicable and conservative for the material yield strength up to 550 MPa

Structural performance on bolted sleeved connections between two CFS channel sections subjected to combined bending and shear

An experimental investigation was carried out to study the behavior of the sleeve connection between two cold-formed steel (CFS) channel sections subjected to combined bending and shear. A total of thirty-nine specimens including three control specimens were tested under three-point bending for different parameters such as three types of the span to section depth ratio, three different sleeve lengths, two sleeve thicknesses and two bolt configurations. Each tested specimen consisted of a pair of channel sections braced together using hot rolled angle sections along the length to ensure lateral stability. The test results indicate two different failure modes; local buckling due to combined bending and shear in the purlin section adjacent to sleeve end, and the other is shearing of the self-drilling screw at the tension zone. The moment resistance of the sleeve connection varied directly with the sleeve length to section depth ratio. The interaction study carried out between the proposed critical sleeve moment and shear capacity of the sleeve specimens is found to be conservative with respect to the AISI interaction equation. The resistance factor for load and resistance factor design (LRFD) method and safety factor for allowable strength design (ASD) method is proposed for the design of sleeve connection by considering it as a flexural member. The design uniformly distributed load (wD) of sleeve specimens having an average sleeve length to section depth ratio of 2.17, 3.51, and 4.85 are found to be 80, 103, and 125% the capacity corresponding to control specimen respectively. The proposed design method is also applicable to the design of continuous channel purlin/girt sections with 150 mm depth for any number of spans subjected to UDL

ASSESSMENT OF RAINFALL VARIABILITY IN GIS ENVIRONMENT

Rainfall being the predominant from of precipitation causing stream flow, especially the flood flow in a majority of rivers in India. In the present study, an attempt has been made to assessment the rainfall variation and monitoring with respect to spatial distribution in Thirumanimuttar River Sub Basin of Cauvery River, South India. To achieve the aim of rainfall variations during Winter (Jan. & Feb.), Summer (Mar. to May), Southwest Monsoon (Jun. to Sep.) and Northeast Monsoon (Oct. to Dec.) were analyzed for a  period of 12 years from 2000 to 2011. These results were taken into platform to prepare the spatial distribution maps. The spatial distribution maps of Southwest- and Northeast monsoon season showed that 1802.78 km2 and 2033.28 km2 of the study area received high rainfall during the respective monsoon seasons. Annual average rainfall spatial distribution map for the years 2000-2011 revealed that 74.43 km2 fell under high rainfall zone in the study area. The results suggest that the model reproduces the number and spatial distribution maps of rainfall extremes with some accuracy, but that mean rainfall and rainfall variability is estimated over dry regions of Thirumanimuttar River Basin, Cauvery River, South India

Experimental study of clip angle bolted connection between two cold-formed steel channels

An experimental investigation was conducted to study the load–deflection relationships, ultimate load and behaviour of beam-to-beam cold-formed steel (CFS) channels connected with clip angles using various connection configurations. In total, 24 specimens were tested to determine the optimum aspect ratio of the clip angle leg in order to improve the connection without significant loss of strength under four-point bending. The parameters studied included the aspect ratio of the attached legs of the clip angle and the thickness of the clip angle. The results showed that a distortional buckling mode of failure occurred in either one leg or both legs of the clip angle depending on the clip angle thickness and the aspect ratio of the anchored leg and the loaded leg connected to the CFS channel. Graphs of rotational stiffness against the percentage of ultimate moment were plotted to determine the ductility of the connection. The experimental results from this work indicate that the design equations from a previous study in the literature are slightly conservative at service load and over conservative at ultimate load

Experimental study on ultimate strength of bolted L shaped sleeve joints between CFS lipped channel sections

This study aims to understand the behavior of bolted L shape sleeve joint connecting two Cold-Formed Steel (CFS) channel sections. A total of thirty-two specimens were experimentally tested under three-point bending. Three different series namely, (A) control specimen with two different span lengths, (B) sleeved specimen with the flange of sleeve connector capping the compression zone, and (C) sleeved specimen with the flange of sleeve connector capping the tension zone were tested. The parameters considered in this study include (i) the span length (Lt), (ii) sleeve length to section depth ratio (β), and (iii) thickness of sleeve connector (LS). The experimental results revealed that the ultimate moment resistance of specimens with a 2.5 mm thick sleeve connector was 19 to 73% higher than 2.0 mm thick sleeve specimens. The moment capacity of series C specimens was about 90–103% of that of the series B specimens. Based on the experimental results, design predictor equations were suggested to determine the moment resistance of sleeve specimens with respect to β. In addition, reliability studies were done for test series B to determine the safety and resistance factors for allowable strength design (ASD) method and load and resistance factor design (LRFD) method respectively. The equivalent and design uniformly distributed load (UDL) was determined based on the combined effect of shear and bending. © 2020 Elsevier Lt

Comparative experimental studies on the web cleat bolted CFS beam-to-column connection

Cold-formed steel (CFS) clip angles/web cleats are widely used as connectors between two CFS members. This study aims to determine the efficiency of a three bolted web cleat over a two-bolted web cleat joint between the beam-column predominantly subjected to a shear load. A total of 26 specimens were studied to investigate the three bolted web cleat configuration by considering two different parameters: (i) thickness of the web cleat (TC) and (ii) the aspect ratio (L/B) of the web cleat leg attached to the column. The experimental results show that the ultimate load increases with a decrease in the aspect ratio of the web cleat leg attached to the column. In addition, the experimental loads of three-bolted configuration were 13 to 95% higher than the corresponding two-bolted configuration. Two types of failure modes were observed: (i) local buckling and (ii) bearing failure of CFS beam under the loading points. The lateral deflection of the column, relative rotation of the connections, and vertical deflection under the loading points were measured and analysed. The nominal shear values calculated from available equations in the past studies are over-conservative when compared to the observed experimental shear values. Hence, a new design equation is suggested for the design of three-bolted web cleat configuration with some specified limits. Besides, reliability studies were performed for the existing and proposed equations for the design of web cleat with three-bolt configuration. © 2020 Elsevier Lt