File Name: environmental studies by kaushik and kaushik chatterjee.zip
Surface modification of metallic biomedical implants are often performed using chemical or mechanical methods in order to make them more bio-active or resistant against surface-induced phenomena such as wear, corrosion or corrosion fatigue. The hardness of the surface was found to increase up to a certain duration of SMAT, due to increased degree of deformation on the surface.
It seems that you're in Germany. We have a dedicated site for Germany. The text demonstrates how candidate stochastic optimization techniques like Particle swarm optimization PSO , harmony search HS algorithms, covariance matrix adaptation CMA etc.
E-mail: sbose iisc. E-mail: agarwalvipul84 gmail. Molybdenum disulfide MoS 2 , with its unique optical and electrical properties, has been explored for a variety of applications in the recent past. Still, its capabilities in point-of-use heavy metal ion removal remain to be explored. Herein, for the first time using a facile approach, we fabricated three-dimensional 3D MoS 2 foam from exfoliated single to few-layered MoS 2 sheets for the selective exclusion of heavy metals and stringent bactericidal response.
This foam was able to exclude Moreover, the foam exhibits selective toxicity towards bacterial cells while showing no observable toxicity towards mammalian cells.
The foam can be recycled and reused for at least five cycles under accelerated conditions and thus can be used for a promising non-cytotoxic, facile, and environmentally benign process for inline water remediation to remove heavy metal ions from the feed and as a potential antibacterial agent. There are many approaches for faster reclamation of heavy metals like chemical precipitation, ion exchange, adsorption, membrane filtration, and electrochemical technologies.
These membranes have suffered from significant limitations such as: i introduction of friction against moving water compromising the structural integrity of the membrane over time; ii sensitivity towards changing pH; and iii probable hydration of the surface functional groups on GO leading to increases in the interlayer spacing and therefore, reduction in membrane selectivity to ions.
MoS 2 has been envisioned to circumvent the limitations associated with GO-based membranes. Unlike GO, MoS 2 nanosheets lack surface functional groups making them inert to hydraulic resistance and swelling which could potentially lead to higher water flux.
Further, research on the use of MoS 2 2D sheets in the form of stacked membranes for water filtration has just started emerging. It has been limited to desalination of particular species like sodium etc. However, in this study, the removal of Pb ions could only be achieved by surface adsorbing these 2D nanosheets on alumina or silica substrates.
There has been no theoretical or experimental report demonstrating the applicability of 3D MoS 2 architectures in toxic heavy metal removal. Attempts towards the fabrication of 3D MoS 2 structures have been reported in some reports using metal or carbon-based materials for electro-catalytic or energy applications only.
This novel material can be deployed for reversible adsorption and desorption of toxic metal ions from water and to yield harsh bactericidal response to fecal coliforms.
Our system, unlike other present adsorbents, can be re-used with ease, and exhibits selective bacterial toxicity with no observable toxicity towards somatic cells. Taken together, this foam can be the next generation point of use system for quick water decontamination.
To exploit the versatility of the exfoliated sheets, hierarchical 3D MoS 2 foam was obtained by lyophilization of the colloidal dispersion of BSA exfoliated MoS 2 nanosheets refer to Scheme 1. Fourier transform infrared spectroscopy FTIR was performed on the protein exfoliated foam and compared with that of the bulk MoS 2 to preliminarily characterize the presence of BSA Fig.
The foam exhibited a 3D interconnected open network structure mediated by a low level of restacking of the nanosheets, which was expected from the lyophilization step Fig. To ascertain the level of restacking, XRD was carried out on the fabricated foam.
In Fig. Notably, the foam retained the unique optical properties which are otherwise considered exclusive to the exfoliated single to few-layered MoS 2 nanosheets. The blue shift observed in the PL emission spectra can be attributed to the stress introduced in the system by the disordered stacking of the nanosheets upon lyophilization.
The average rejection by bulk MoS 2 for feed concentrations of 5 ppm, 10 ppm, 20 ppm, and 50 ppm were The average rejection by the bulk MoS 2 control refer to Fig. The permeation of water and other ionic molecules through nonporous materials like MoS 2 is generally facilitated via a interlayer d -spacing channels. The low level of re-stacking of the exfoliated nanosheets upon lyophilization with reduced d -spacing protein stitched the adjacent MoS 2 sheets generated interconnected pores, which provided the nano-channels for water permeation and trapped the metal ions illustrated in Scheme 2.
Herein, the critical factor that contributed towards quick removal of heavy metal impurities was size based sieving due to reduced d -spacing. The water, as well as heavy metal ions, was channelized through the slits as well as the interplanar spaces. Since the ions are more prominent in size, they are excluded at the interplanar space rather than ending up in the permeate resulting in enhanced removal of heavy metals. It can be seen that the ions are entrapped in the foam architecture.
These agglomerates were packed and rearranged randomly, and thus act as flow barriers to water molecules as well as metal ions. Although the water molecules as well as metal ions experience a resistive path while flowing through the material but, since the agglomerates are not broken, some ions elute through the least resistive path i. It can be seen that even after passing the accelerated feed of 20 ppm through the system, the efficiency of heavy metal recovery was not compromised.
It can be seen that the foam retained its properties even after cyclic re-dispersion and lyophilization. The control for these tests was bulk MoS 2. In the presence of interfering ions, there was a marginal reduction in efficiency in arsenic and lead removal.
However, the As III removal was recorded to be It is important to note that all the studies are based on graphene as the base 2D material, and there is no reported work on either MoS 2 or MoS 2 based foams for remediating toxic lead and arsenic-based contaminants.
Further, the reported efficiencies of lead and arsenic in this work are considerably superior to the existing literature reports. The efficacy of the 3D foam to remediate bacterial contamination was demonstrated herein using E.
It can be seen from Fig. The mechanism of bacterial reduction by the exfoliated MoS 2 sheets is mediated through the generation of reactive oxygen species, 22,54,55 and by scissoring effects.
In contrast, for the bulk MoS 2, only The rate of increase in the ROS level obtained correlated well with the time dependent reduction in bacterial cell viability, which indicates that the sharp edges of the nanosheets in the foam would have potentially induced intracellular membrane stress before scissoring the bacterial cells thereby causing cell death. One of the key challenges in the fabrication of membrane filters or any other filtration material is their impact on the biological and ecological environments.
Such exposure was predominantly mediated by leaching of the material either through the compromised structural integrity with time or hydraulic rupture.
Furthermore, it is important to elucidate whether the toxicity of the fabricated foam is selective and limited only to microbial cells. To this end, we evaluated the in vitro cytotoxicity of the re-dispersed foam in immortalized mouse lymphoid endothelial SVEC cells.
No change was observed in the growth and viability of the SVEC cells at any of the concentrations studied. Moreover, fluorescence imaging of the cells revealed no change in the cell morphology, highlighting the biocompatibility of the nanosheets Fig.
Herein, we addressed this issue by using MoS 2 which is resistant to swelling due to lack of any surface functional groups. The exfoliated sheets were lyophilized to obtain a 3D MoS 2 foam. These foams were then used as a point of use adsorbent to remediate arsenic and lead-based heavy metal contaminants. Not only were the foams effective at an accelerated concentration up to 50 ppm, but the foams were also easily re-useable and were effective in the presence of interfering ions as well.
Further, these foams were effective in remediating pathogenic bacteria E. Received 28th November , Accepted 5th May Scheme 1 Formation of 3D foam from few layers of MoS 2 nano-platelets using lyophilization. Scheme 2 Flow path for water and ions in bulk MoS 2 and exfoliated foam.
It seems that you're in Germany. We have a dedicated site for Germany. Applied Environmental Biotechnology: Present Scenario and Future Trends is designed to serve as a reference book for students and researchers working in the area of applied environmental science.
The system can't perform the operation now. Try again later. Citations per year. Duplicate citations.
History of the department : The two year post graduate course in the Environmental Science Department commenced in the year with a current intake capacity of 16 students.
Comparative study of keratin extraction from human hair. Kaushik Chatterjee. It presents various applications of environmental studies that involve the use of living organisms, Editors: Kaushik, Garima Ed. Free Preview. Written by a. Chatterjee, T. Reorienting environment policy in India towards a local area-based development and management paradigm.
Просто все привезти. Абсолютно. Ничего не упустив.
Затем он его уничтожит, и Цифровая крепость навсегда исчезнет из Интернета. - Действуй своим маячком очень осторожно, - сказал Стратмор. - Если Северная Дакота заподозрит, что мы его ищем, он начнет паниковать и исчезнет вместе с паролем, так что никакая штурмовая группа до него не доберется. - Все произойдет, как булавочный укол, - заверила его Сьюзан.
Он держит нас в заложниках. Внезапно она встала. В голосе ее прозвучала удивительная решимость: - Мы должны установить с ним контакт.
Однако выстрелов не последовало. Мотоцикл каким-то чудом перевалил через гребень склона, и перед Беккером предстал центр города. Городские огни сияли, как звезды в ночном небе. Он направил мотоцикл через кустарник и, спрыгнув на нем с бордюрного камня, оказался на асфальте. Веспа внезапно взбодрилась.
Она хорошо знала, что процессор перебирает тридцать миллионов паролей в секунду - сто миллиардов в час. Если ТРАНСТЕКСТ до сих пор не дал ответа, значит, пароль насчитывает не менее десяти миллиардов знаков. Полнейшее безумие. - Это невозможно! - воскликнула она. - Вы проверили сигналы ошибки.
Глаза Клушара расширились.
Ничего не трогайте. Ничего не читайте. - Энсей Танкадо… родился в январе… - Пожалуйста, - вежливо сказал Беккер. - Положите на место.
Я преподаватель, а не тайный агент, черт возьми. И тут же он понял, почему все-таки Стратмор не послал в Севилью профессионала. Беккер встал и бесцельно побрел по калле Делисиас, раздумывая на ходу, что бы предпринять.
Это просто бессмысленный набор букв… Слова застряли у него в горле, глаза расширились.
Your email address will not be published. Required fields are marked *