Polishing slurries used in chemical-mechanical planarization (CMP) of copper typically include a complexing agent and an oxidizer. Our present work investigates the effectiveness of citric acid as a ...complexing agent for Cu with H2O2 employed as an oxidizer. We show that the rate of copper removal from Cu increases when both citric acid and H2O2 are used in acidic solutions (pH 4.0) and decreases drastically in alkaline solutions (pH 8.0), as well as in citric acid without any H2O2 in the slurry. We investigate the underlying surface reactions of these effects by using Fourier transform electrochemical impedance spectroscopy (FTEIS) in combination with potentiodynamic measurements. We analyze the relative roles of citric acid, H2O2, and solution pH in Cu removal, and develop a reaction scheme describing the surface chemistry of Cu in this system. The results presented here also demonstrate how FTEIS can be used for quantitative investigation of surface reactions in complex CMP systems.
Ab initio calculations are performed on the electronic, structural, elastic and optical properties of the cubic per- ovskite KCdF3. Tile Kohn Sham equations are solved by applying the full potential ...linearized augmented plane wave （FP-LAPW） method. The exchange correlation effects are included through the local density approximation （LDA ）, generalized gradient approximation （GGA） and modified Becke-Johnson （mBJ） exchange potential The calculated lattice constant is in good agreement with the experimental result. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young＇s modulus and Poisson＇s ratio are calculated. KCdF3 is ductile and elastically anisotropic. The calculations of the electronic band structure, density of states （DOS） and charge density show that this compound has an indirect energy band gap （M-F） with a mixed ionic and covalent bonding. The contribution of the different bands is analyzed from the total and partial density of states curves. Optical response of the dielectric functions, optical reflectivity, absorption coefficient, real part of optical conductivity, refractive index, extinction coefficient and electron energy loss, are presented for the energy range of O-40eV. The compound KCdF3 can be used for high-frequency optical and optoelectronic devices.
Probiotics are microorganisms which when administered in adequate amounts confer health benefits to the host. A leading pharmaceutical company producing
Bacillus coagulans
as a probiotic was facing ...the problem of recurring phage attacks. Two mutants viz. B. co PIII and B. co MIII that were isolated as phage resistant mutants after UV irradiation and MMS treatment of phage sensitive
B. coagulans
parental culture were characterized at functional and molecular level and were noted to have undergone interesting genetic changes. The non-specific genetic alterations induced by mutagenesis can also lead to alterations in cell performance. Hence, in the current study the parental strain and the two mutants were selected for shake flask optimization. Plackett–Burman design was used to select the significant culture variables affecting biomass production. Evolutionary operation method was applied for further optimization. The study showed wide variations in the nutritional requirements of phage resistant mutants, post exposure to mutagens. An increment of 150, 134 and 152 % was observed in the biomass productions of
B. coagulans
(parental type) and mutants B.co PIII and B.co MIII respectively, compared to the yield from one-factor-at-a-time technique. Using Logistic and modified Leudeking–Piret equations, biomass accumulation and substrate utilization efficiency of the bioprocess were determined. The experimental data was in agreement with the results predicted by statistical analysis and modelling. The developed model may be useful for controlling the growth and substrate consumption kinetics in large scale fermentation using
B. coagulans
.
Chemical-mechanical polishing (CMP) of copper was conducted in two acidic (pH 1.3 and 3.8) slurries and one alkaline pH (10∼12) slurry with alumina particles as the abrasives. In acidic media with ...0.1 M Fe(NO
3)
3 as a copper etchant and
1H-benzotriazole (BTA) as an inhibitor, copper polish rate increases linearly with solids concentration in the polishing slurry. The polish rate increased linearly with increasing downward pressure and rotational speed with all of the above slurries. However, the Preston equation does not represent the polish rate data. Inclusion of an additional velocity term, representing the greater dependence of removal rate on the velocity and a constant, representing the purely chemical reactivity of the slurry which is, in general, higher than the static dip rate in the Preston equation, provided a more satisfactory representation of the data. The effect of the concentration of various slurry chemicals on the added constant term was investigated using a bench-top Struers DAP-V polisher. As expected, addition of BTA significantly reduces the value of this constant. Also some data on polish selectivity and the effect of alumina morphology are presented.
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IJS, IMTLJ, KILJ, KISLJ, NUK, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Recombinant protein purification is facilitated using high expression systems which produce larger quantities of streptokinase protein as inclusion bodies. As the accumulation of active streptokinase ...is toxic to the host cells, we have optimized the conditions to achieve large amounts of streptokinase in the form of inclusion bodies. The solubility and yield of pure protein are highly dependent on various combinations of chemical additives, ionic and non-ionic detergents and salts, with solubilizing agents followed by refolding of denatured protein into active form. As the extraction of the purified streptokinase from inclusion bodies requires denaturation and a subsequent refolding step, careful balancing steps were needed to develop under different controlled conditions. Here the purified fragments of refolded proteins were screened to select the conditions that yield the active streptokinase having native conformation. The maximum specific activity of the purified streptokinase was achieved by these methods. The refolded recombinant streptokinase was analyzed by RP-HPLC showing a purity of 99%. Size exclusion chromatography profile shows that there are minimal aggregates in the active streptokinase protein and the percentage of renaturation is around 99%.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In the present study, activated flyash -- a low-cost adsorbent, is used as for Cr(VI) removal from aqueous solutions. Flyash is activated by giving heat treatment and with the use of concentrated ...sulfuric acid (98% w/w). Batch adsorption experiments are carried out to investigate the effect of influencing process parameters such as initial pH, change in pH during adsorption, contact time, adsorbent amount, and initial Cr(VI) concentration. The maximum adsorption of Cr(VI) on activated flyash is found at an initial pH value of 1. The value of pH increases with increase in adsorption of Cr(VI). The equilibrium data for adsorption of Cr(VI) on activated flyash is tested with different adsorption isotherm models such as Langmuir, Freundlich, Redlich-Peterson, Koble-Corrigan, Tempkin, Dubinin-Radushkevich and generalized isotherm models. The Koble-Corrigon isotherm model is found to be the most suitable one for Cr(VI) adsorption using activated flyash. The maximum adsorption capacity obtained is 21.9 mg g super(-1) at a pH value of 1. The adsorption process follows the second order kinetics and the corresponding rate constants are obtained at different initial Cr(VI) concentrations. Desorption of Cr(VI) from activated flyash using acid and base treatment shows a higher desorption efficiency by more than 85%. A feasible methodic solution for the disposal of contaminant (acid and base solutions) containing high concentration of Cr(VI) obtained during the desorption process is proposed.
Carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) are important biogenic green house gases (GHGSs) from agricultural sector contributing to global warming. Temperature and rainfall play an ...important role in GHGS fluxes and information on their role in rainfed crops and systems is very scanty. Field studies were conducted at Hyderabad, India during 2012 rainy season to quantify GHGSs fluxes from two important food crops grown widely in rainfed regions viz. sorghum and pigeonpea. Quantum of fluxes ranged from 26 - 85 mg CO2 - C m-2 h-1 in case of CO2 and 18 – 68 μg N2O-N m-2 h-1 in case of N2O at different stages of crop growth. Cumulative seasonal fluxes are 1.18 and 1.24 Mg CO2-C ha-1 and 0.78 and 0.94 kg N2O-N ha-1, in sorghum and pigeonpea, respectively. Ambient temperature and rainfall significantly influenced CO2 fluxes. CO2 fluxes increased with increase in temperature from 25.9 °C to 31 °C and fluxes were highest at 28.4 °C in pigeonpea and at 27.7 °C in sorghum. Quantum of CO2 fluxes were highest at grain filling stage in sorghum and grand growth period in pigeonpea. N2O fluxes increased with increase in temperature and moisture availability. These results provide evidence that rainfed crops in semi-arid regions contribute significant CO2 and N2O fluxes which are influenced by temperature and rainfall, thus warrant further studies.
Objective
To describe the development and implementation of a population-based screening programme for sickle cell disease (SCD) implemented in 12 SCD-endemic and tribal-dominated primary/community ...health centres (PHCs/CHCs) across six districts of India.
Setting
India reports a huge burden of SCD, especially among indigenous (tribal) communities. However, there is no state-led SCD programme in many places, and systematic screening is absent. This situation necessitates developing a model of population screening.
Methods
This programme was meant to screen all people and was carried out in three tiers. The first tier was a symptomatic survey carried out by community health workers. Regular health workers then screened those referred by sickle cell solubility test at sub-health centres as the second tier. The third tier was confirmation by haemoglobin electrophoresis at PHCs/CHCs. Communities were mobilised and prepared to accept the screening. Capacity building of health facilities was ensured through training and supply of equipment and material.
Results
Initial observation based on six months’ data revealed that out of the 110,754 tribal population of 12 PHCs/CHCs, 8418 (7.6%) were identified in the symptomatic survey. Subsequently, 9416 people, including the above 8418, underwent the solubility test, and 2607 (27.7%) were found to be positive. Of these, 1978 (78.9%) underwent electrophoresis. About 64.2% were found to be positive for sickle haemoglobin (233 (18.4%) SCD and 1036 (81.6%) SCD trait).
Conclusions
The study demonstrates the feasibility of establishing a population-based screening programme in the primary health care system. It is easy to implement in tribal habitations as part of the proposed national SCD/haemoglobinopathies programme.
India is in the process of strengthening the trauma care system, and assessment of the current situation using standard guidelines has immense use. This study reports the status of trauma care ...facilities in India, with a broad framework of guidelines for essential trauma care by the World Health Organization.
This study is part of a multicentric intervention study to standardize structured trauma care services in five Indian cities. Thirty trauma care facilities (five level I, 10 level II, and 15 level III facilities) were included. Data on the availability of equipment and manpower were collected. Availability of knowledge + skills and equipment + supplies was assessed based on the guidelines for essential trauma care by World Health Organization.
There is almost 100% availability of services and equipment in level I hospitals, but availability varied between 50% and 100% at level II facilities. Very fewer number of services are available at level III facilities. Inadequacy of equipment is reported in level II and III facilities. Only level I facilities have required human resources. Availability of resources in terms of knowledge and equipment of different skills indicated that overall optimal level is observed in level I hospitals. Level II facilities are more deficient in nursing and paramedic staff, and level III facilities reported deficiencies in all categories.
A significant imbalance between recommended resources and the resources that are available in the trauma care facilities was noted. Hence, the study warrants urgent strengthening of trauma care facilities, particularly of level II and III facilities.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper investigates the network connectivity properties of a vehicular ad hoc network (VANET) from a physical layer perspective. Specifically, we investigate the minimum transmit power used by ...all vehicles, sufficient to guarantee network connectivity. As opposed to the conventional graph-theoretic approach, in this paper, the network connectivity problem is analyzed according to a physical layer-based quality of service constraint. Under this approach, a multi-hop path joining a pair of vehicles in a VANET is said to be connected if and only if the average route BER meets a target requirement. We derive closed form analytical expression for the minimum transmit power sufficient to ensure network connectivity. We also derive analytical expression for the maximum number of hops, a packet can traverse satisfying the route BER constraint, for a given transmit power. The validity of our theoretical analysis is verified by extensive simulation studies. The analysis provides a framework for investigating the impact of traffic dependent parameters such as vehicle arrival rate, vehicle density, mean and standard deviation of vehicle speed, highway length and physical layer-based parameters such as path loss exponent, fading factor, Doppler spread, and data rate on VANET connectivity characteristics.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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