Purification,characterization and production optimization of a vibriocin produced by mangrove associated vibrio parahaemolyticus

Objective:To identify a potential bacterium which produces antimicrobial peptide(vibriocin),and its purification,characterization and production optimization.The bacteria subjected in the study were isolated from a highly competitive ecological niche of mangrove ecosystem.Methods:The bacterium was characterized by phenotype besides 16S rRNA gene sequence analysis.The antibacterial activity was recognised by using agar well diffusion method.The vibriocin was purified using ammonium sulphate precipitation,butanol extraction,gel filtration chromatography,ion-exchange chromatography and subsequently,by HPLC.Molecular weight of the substance identified in SDS-PAGE.Production optimization performed according to Taguchi's mathematical model using 6 different nutritional parameters as variables.Results:The objective bacterium was identified as Vibrio parahaemolyticm.The vibriocin showed 18 KDa of molecular mass with mono peptide in nature and highest activity against pathogenic Vibrio harveyi.The peptide act stable in a wide range of pH,temperature.UV radiation,solvents and chemicals utilized.An overall^20%of vibriocin production was improved,and was noticed that NaCl and agitation speed played a vital role in secretion of vibriocin.Conclusion:The vibriocin identified here would he an effective alternative for chemically synthesized drugs for the management of Vibrio infections in mariculture industry.

Ambient noise during rough weather and cyclones in the shallow Bay of Bengal

This paper presents ambient noise analysis during rough weather, using time series measurements from an automated noise measurement system in the shallow southwest Bay of Bengal during October–November 2010. The period witnessed low-pressure events including depressions and cyclones, with JAL cyclone passing close to the measurement site. The time series noise level shows a shift in mid-October, after which deep depressions and cyclones formed, with an average increase of 5–10 dB in the lower band and 2–3 dB in the higher band of frequencies. Furthermore, correlation between noise level and wave height(data from wave rider buoy deployed at the site) for sea state scale 3 and above shows good correlation with an increase in noise level with increase in wave height, the effect being most pronounced at 0.5 kHz. The noise captured during JAL was analysed to identify the spectrum components due to convective precipitation and heavy wind/wave activity and shows anomalously high levels during the crossing of the cyclone. Rain noise spectra from the rain bands associated with the wall of the cyclone are reported. This has been correlated with radar refl ectivity measurements to ascertain the presence of rain, and discriminate between convective and stratiform types. Also, vertical directionality pattern of ambient noise during JAL showed clearly distinct surface contributions. On the whole, knowledge of ambient noise fields during high sea states and precipitation is useful in optimizing SONAR performance. The findings at the study site have been compared with measurements from other shallow water locations during rough weather.

A Note on the Derivation of Wave Action Balance Equation in Frequency Space

In this paper the wave action balance equation in terms of frequency-direction spectrum is derived. A theoretical formulation is presented to generate an invariant frequency space to replace the varying wavenumber space through a Jacobian transformation in the wave action balance equation. The physical properties of the Jacobian incorporating the effects of water depths are discussed. The results provide a theoretical basis of wave action balance equations and ensure that the wave balance equations used in the SWAN or other numerical models are correct. It should be noted that the Jacobian is omitted in the wave action balance equations which are identical to a conventional action balance equation.

Simplified Design Procedure of Monopile Foundation for Offshore Wind Turbine in Gujarat, India

任何东西(近海风汽轮机) 当前被看作可更新的精力的可靠来源。为首都的 20%-25% 的任何东西支持结构报道花费了为近海风安装。包含风汽轮机结构的初步的尺寸的评价的可行性前研究需要为到达工程的商业生存能力的起始的花费被表现。论文的主要目的是为商业生存能力并且基础堆积的近似缩放获得初步的配置。设计方程和诺模图被建议因为 monopile 的快初步的设计成立了 Gujarat 近海的定位的风汽轮机。参量的研究在由改变水深度和沙的性质的空 monopile 的各种各样的配置上是带外面的。基础的非线性的静态的分析被执行考虑空气动力学的力量和水动力学力量为各种各样结构并且土壤参数。风汽轮机的基础设计基于 API (美国石油研究所) 标准。为在装载状况的极端下面的 monopile 支持结构的简化设计方法论基于 multivariable 被介绍线性回归分析。为回归分析的输入变量是水动力学数据，沙的内部磨擦的角度，和输出变量是长度和 monopile 的外部直径。这简化方法论是适用的在风力量公园预先学习。

Coral Reef Recovery Status in South Andaman Islands after the Bleaching Event 2010

The Andaman and Nicobar Islands are one of the Union Territories of India, located in the eastern part of the Bay of Bengal. In 2010 summer, the increment in sea surface water temperature (up to 34℃) resulted in the bleaching of about 74% to 77% of corals in the South Andaman. During this event, coral species such as Acropora cerealis, A. humilis, Montipora sp., Favia pallida, Diploastrea sp., Goniopora sp. Fungia concinna, Gardineroseries sp., Porites sp., Favites abdita and Lobophyllia robusta were severely affected. This study is to assess the recovery status of the reef ecosystem by estimating the percentage of Live Coral cover, Bleached coral cover, Dead coral with algae, Rubble, Sandy flat, Algal assemblage and other associated organisms. The sedimentation rate (mg cm-2 d-1) and coral coverage (%) were assessed during this study period. The average sedimentation rate was ranged between 0.27 and 0.89 mg cm-2 d-1 . The observed post bleaching recovery of coral cover was 21.1% at Port Blair Bay and 13.29% at Havelock Island. The mortality rate of coral cover due to this bleaching was estimated as 2.05% at Port Blair Bay and 9.82% at Havelock Island. Once the sea water temperature resumed back to the normal condition, most of the corals were found recovered.

Computational Study on Micro Shock Tube Flows with Gradual Diaphragm Rupture Process

Gas flows through micro shock tubes are widely used in many engineering applications such as micro engines, particle delivery devices etc. Recently, few studies have been carried out to explore the shock wave excursions through micro shock tubes at very low Reynolds number and at rarefied gas condition. But these studies assumed centered shock and expansion waves, which are generally produced by instantaneous diaphragm rupture process. But in real scenario, the diaphragm ruptures with a finite rupture time and this phenomenon will significantly alter the shock wave propagation characteristics. In the present research, numerical simulations have been carried out on a two dimensional micro shock tube model to simulate the effect of finite diaphragm rupture process on the wave characteristics. The rarefaction effect was simulated using Maxwell’s slip wall equations. The results show that shock wave attenuates rapidly in micro shock tubes compared to conventional macro shock tubes. Finite diaphragm rupture causes the formation of non-centered shock wave at some distance ahead of the diaphragm. The shock propagation distance is also drastically reduced by the rupture effects.

Output Prediction of Helical Microfiber Temperature Sensors in Cycling Measurement by Deep Learning

The inconsistent response curve of delicate micro/nanofiber(MNF)sensors during cycling measurement is one of the main factors which greatly limit their practical application.In this paper,we proposed a temperature sensor based on the copper rod-supported helical microfiber(HMF).The HMF sensors exhibited different light intensity-temperature response relationships in single-cycle measurements.Two neural networks,the deep belief network(DBN)and the backpropagation neural network(BPNN),were employed respectively to predict the temperature of the HMF sensor in different sensing processes.The input variables of the network were the sensor geometric parameters(the microfiber diameter,wrapped length,coiled turns,and helical angle)and the output optical intensity under different working processes.The root mean square error(RMSE)and Pearson correlation coefficient(R)were used to evaluate the predictive ability of the networks.The DBN with two restricted Boltzmann machines(RBMs)provided the best temperature prediction results(RMSE and R of the heating process are 0.9705℃and 0.9969,while the values of RMSE and R of the cooling process are 0.7866℃and 0.9977,respectively).The prediction results obtained by the optimal BPNN(five hidden layers,10 neurons in each layer,RMSE=1.1266℃,R=0.9957)were slightly inferior to those obtained by the DBN.The neural network could accurately and reliably predict the response of the HMF sensor in cycling operation,which provided the possibility for the flexible application of the complex MNF sensor in a wide sensing range.

Studies on biodiversity and bioprospecting of active mud volcano associated bacteria and actinobacteria from Baratang,Andaman Islands,India

A total of 79 bacteria and 101 actinobacteria strains were isolated from the sediment samples of the different points of Baratang mud volcano viz.,point of the eruption(M),middle of the volcano(MD),and the dried part of the mud volcano(E).Based on the biochemical and molecular characterization,the isolates were categorized under the phyla Proteobacteria,Firmicutes and Proteobacteria included representatives of Classes Alphaproteobacteria,Gammaproteobacteria and Deltaproteobacteria of 29 genera with 38 distinct ribotypes.Thirty-eight bacterial strains from four different regions of mud volcano revealed excellent activity for indole-3-acetic acid(IAA)production.Excellent antagonistic property,plant growth promoting properties such as IAA production,phosphate,potassium and zinc solubilization were identified in Bacillus megaterium NIOT_MV 31 strain of 38 studied isolates.In this study,we investigated the optimization of IAA production by B.megaterium NIOT_MV 31 and its formulation as a plant growth promoter to improve economic and agricultural development.Maximum IAA yield was achieved using optimal conditions(42.63 mg/mL)in the presence of optimized tryptophan after 4 days of incubation.Twofold increase in the plant growth parameters were observed to that of control plants.Optimization of culture conditions resulted in a fourfold increase in IAA production by B.megaterium NIOT_MV 31 cells.The results clearly demonstrated that,B.megaterium NIOT_MV 31 holds great potential as a source for IAA production and may be useful for commercial applications.

Non-linear buckling analysis of imperfect thin spherical pressure hull for manned submersible

Thin spherical pressure hulls are used as a human occupancy in deep water applications.DNV and other standards specify the imperfection allowed for pressure hulls.Numerical analyses are carried out to find the buckling pressure for both perfect and imperfect thin spherical pressure hulls,considering the geometric and material non-linearities.It is observed that there is a huge variation in the elastic and inelastic buckling pressure in perfect spherical pressure hulls.Moreover,if the manufacturing imperfections are considered in the inelastic numerical analysis,still there is a reduction in the buckling pressure.Design criteria,for deep water pressure hulls,is that both buckling pressure and yield pressure must be greater than the design pressure.In the elastic analysis,if t/D>0.006 buckling pressure is always greater than the yield pressure whereas in the inelastic analysis,the buckling pressure is falling below the yield pressure for all t/D ratios.Hence,inelastic numerical analysis with manufacturing imperfection has to considered in the design of deep water spherical pressure hulls of manned submersibles.

Circular cylinder wakes and their control under the influence of oscillatory flows: A numerical study

Understanding and control of wake vortices past a circular cylinder is a cardinal problem of interest to ocean engineering.The wake formation and vortex shedding behind a variety of ocean structures such as spars,are subjected to fatigue failure limiting their life span.The additional influences due to ocean waves and currents further exacerbate these effects.In the present study,flow past an isolated circu-lar cylindrical structure subjected to an oscillatory upstream are numerically investigated.These studies involve high resolution simulations over the low Reynolds number range(100-200).Although the prac-tical range of interest is in high Reynolds number range of 103-105,the flow physics and a number of qualitative and quantitative aspects are similar to the low Reynolds number flows.In the high Reynolds number range,statistical averaging tools in conjunction with suitable closure models would be neces-sary.The control of wake vortices is achieved with the aid of two small rotors located in the aft of the main cylinder.A control algorithm was coupled to determine the quantum of actuation to the rotating elements.Although control of wake vortices was observed for harmonic in-let forcing,residual vortical structures were found to persist at higher amplitudes of oscillation.To study the efficacy of this control,numerical simulations were further extended,when the circular cylinder was flexibly mounted.The con-trol of flow induced vibrations was observed to be reasonably effective in controlling the wake generated behind the main cylinder due to oscillatory upstream.

An approach to operational risk modeling and estimation of safety levels for deep water work class remotely operated vehicle-A case study with reference to ROSUB 6000

This paper presents a quantitative approach to operational risk modeling and estimation of safety integrity levels,required for the deep water electric work class remotely operated vehicle with reference to ROSUB6000 developed by the National Institute of Ocean Technology,India.ROSUB6000 is used for carrying out bathymetric surveys,gas hydrate surveys,poly-metallic nodule exploration,salvage operations,and meeting emergency response situations.The system is expected to be in operation for a period of 300 h per year,and has to be extremely safe and reliable.Methods and models for the quantitative assessment of operational safety and estimation of safety integrity levels for ROV are seldom available in the deep water intervention industry.The safety instrumented functions implemented in the ROV should be able to meet the SIL requirements of specific mission.This study indicates that the required safety factors are implemented into the design of the state-of-the-art ROV ROSUB 6000,considering IEC 61508/61511 recommendations on Health,Safety and Environment and it is found that the system is able to meet the required SIL for seven identified functions.This paper gives the design and safety engineers in the ROV industry,an overview of the numerical operational risk assessment methods and safety-centered ROV engineering.

Fault-tolerant design approach for reliable offshore multi-megawatt variable frequency converters

Inverters play a key role in realizing reliable multi-megawatt power electronic converters used in offshore applications,as their failure leads to production losses and impairs safety.The performance of high power handing semiconductor devices with high speed control capabilities and redundant configurations helps in realizing a fault-tolerant design.This paper describes the reliability modeling done for an industry standard,3-level neutral point clamped multi-megawatt inverter,the significance of semiconductor redundancy in reducing inverter failure rates,and proposes methods for achieving static and dynamic redundancy in series connected press pack type insulated gate bipolar transistors(IGBT).It is identified that,with the multi megawatt inverter having 3+2 IGBT in each half leg with dynamic redundancy incorporated,it is possible to reduce the failure rate of the inverter from 53.8%to 15%in 5 years of continuous operation.The simulation results indicate that with dynamic redundancy,it is possible to force an untriggered press pack IGBT to short circuit in<1 s,when operated with a pulse width modulation frequency of 1 kHz.