Kinetic study approach of remazol black-B use for the development of two-stage anoxic-oxic reactor for decolorization/biodegradation of azo dyes by activated bacterial consortium

The laboratory-isolated strains Pseudomonas aeruginosa, Rhodobacter sphaeroides, Proteus mirabilis, Bacillus circulance, NAD 1 and NAD 6 were observed to be predominant in the bacterial consortium responsible for effective decolorization of the azo dyes. The kinetic characteristics of azo dye decolorization by bacterial consortium were determined quantitatively using reactive vinyl sulfonated diazo dye, remazol black-B (RB-B) as a model substrate. Effects of substrate (RB-B) concentration as well as different substrates (azo dyes), environmental parameters (temperature and pH), glucose and other electron donor/co-substrate on the rate of decolorization were investigated to reveal the key factor that determines the performance of dye decolorization. The activation energy (E(a)) and frequency factor (K(0)) based on the Arrhenius equation was calculated as 11.67 kcal mol(-1) and 1.57 x 10(7)mg lg MLSS(-1)h(-1), respectively. The Double-reciprocal or Lineweaver-Burk plot was used to evaluate V(max), 15.97 h(-1) and K(m), 85.66 mg l(-1). The two-stage anoxic-oxic reactor system has proved to be successful in achieving significant decolorization and degradation of azo dyes by specific developed bacterial consortium with a removal of 84% color and 80% COD for real textile effluents vis-à-vis >or=90% color and COD removal for synthetic dye solution.     

Sediment transport in an active erodible channel bend of Brahmaputra river

Spatial variation of sediment transport in an alluvial sand-bed river bend needs to be understood with its influencing factors such as bank erosion, secondary current formation, land spur and bed-material characteristics. In this study, detailed hydrographic surveys with Acoustic Doppler Current Profiler (ADCP) were conducted at an active erodible river bend to measure suspended load, velocity, bathymetric profile and characteristics of the bed material. Study indicates the presence of multi-thread flow in the channel bend. Local variation of sediment transport is primarily controlled by active bank erosion, land spur and sand bar formation. Vertical distribution of suspended sediment concentration follows a power function with normalized depth. Average bed-material concentration at the reach level is computed from observed sediment profiles, and is compared against various sediment transport functions. Results show that the sediment transport function suggested by Yang gives better predictions for this reach. Transverse bed slopes at critical survey transects were computed from the bathymetric data and evaluated with analytical approaches. Out of three analytical approaches used, Odgaard’s approach estimates the bed slopes fairly close to the observed one. These two functions are suitable in the Brahmaputra river for further morphological studies.     

“单电”的崛起

喜欢便携数码相机时尚靓丽的外观、轻便的造型和简洁的操作方式,但随着了解与使用的深入,你又越来越难以接受其指甲盖大小的传感器所带来的有限画质。     

Lipid profile and fatty acid composition of two silurid fish eggs

The lipid content and the composition pattern of the lipid class including fatty acid composition in the eggs of two different Indian silurid cat fishes Ompok pabda and Wallagu attu have been examined. The lipid content of O. pabda and W. attu (on dry basis) are about 14.7% and 17.8% respectively. The major lipid classes are phospolipid (PL) and triacylglycerol (TAG). The O. pabda egg lipid contains more PL while the W. attu egg lipid contains more TAG. Phosphatidylcholine (PC) constitutes the major phospholipid followed by phosphatidylinositol (PI). PI represents in about 31.7% and 21.3% of total PC in O. pabda and W. attu respectively while phosphatidylethanolamine (PE) (about 28.0%) is significantly higher in the egg of W. attu than O. pabda (9.6%). Cholesterol content in egg of O. pabda is also higher (about 9.6%) than W. attu (4.1%). The lipids are rich in polyunsaturated fatty acids (PUFAs) and they are mainly concentrated in the respective PL fractions. Among PUFAs the arachidonic acid (20:4 n-6 AA) is present at about 9.3% in both egg PL. Eicosapentaenoic acid (20:5 n-3 EPA) is significantly lower in egg lipids of both W. attu (1.8%) and O. pabda (3.2%), whereas docosahexaenoic acid (22:6 n-3 DHA) is predominantly higher (14.6% and 18.1% in W. attu and O. pabda respectively) in their PL fractions.     

Effect of nano CuO addition on the tribo-mechanical behavior of alumina ceramics in non-conformal contact

Sintering of alumina from 1500°C to 1650°C and tribo-mechanical properties at room temperature had been investigated using nano CuO as a sintering aid. Bulk density gradually increases with sintering temperature from 1500°C to 1600°C and is optimized at 1600°C, beyond this, bulk density does not significantly increase at 1650°C. The addition of 2 wt% CuO showed the best result on densification. Densification of about 97.74% was attained at 1600°C with the incorporation of 2 wt% CuO. Nano CuO at grain boundaries forms CuAl₂O₄ liquid which modifies the morphology of the grain and improves mechanical properties. The formation of self-lubricating tribo-film on the wear track results in a low coefficient of friction <0.2 and reduces specific wear rate. 4 wt% CuO addition increases contact tensile stress (σ_max) by 51.2% and high Hertzian contact pressure (P_max≈1.51 GPa) causes plastic deformation of wear track. The re-solidified strengthening bond phase on the wear track simultaneously increases in friction coefficient and wear resistance with CuO addition. The optimizing effect of CuO addition shows that 2 wt% significantly decreases wear rate, and increases hardness and fracture toughness.     

A facile synthesis of nontoxic luminescent carbon dots for detection of chromium and iron in real water sample and bio-imaging

In this study, we have reported the synthesis of luminescent carbon dots (CDs) from indigenous potato sources by simple heating reactions. The as-synthesized CDs exhibited an average size of ~ 5.97 nm with a quantum yield (QY) of 6.08%. Furthermore, the CDs possessed high water-solubility, possibly due to the presence of ─COOH and ─OH groups on their surfaces. The quenching of luminescence of the CDs specifically by Cr⁶⁺ and Fe³⁺ ions was used to detect chromium and iron in the water sample. The minimum limit of detection (LOD) for Cr⁶⁺ and Fe³⁺ ions was found to be 0.012 μM and 0.000549 μM, respectively, in a linear range of 0.5 μM-100 μM and 0.5 μM-5 μM for Cr⁶⁺ and Fe³⁺, respectively, which was well below the concentration specified by WHO. We used our sensing system to detect the metal ions in water from the Brahmaputra River as well as in tannery water. In addition, the MTT-based cell viability experiments showed that the CDs were nontoxic within 200 μg/mL. High quantum yield and the easy uptake of CDs enabled the quick labelling of cytoplasm of the HeLa cells, which can be further attributed to bioimaging applications.     

拍拍模型，放松心情

好山好水，美人异事，这些都是绝佳的拍摄题材，但我们并不是职业摄影师，这些东西不可能一直在我们周围出现。所以，不妨多发掘一些身边的乐趣。例如，拍拍那些讨人喜欢的动漫手办和模型——胸藏丘壑，城市不异山林；兴寄烟霞，阎浮有如蓬岛。     

Evaluating the life cycle environmental performance of chlorine disinfection and ultraviolet technologies

With increasing emphasis on promoting a sustainable ecological future and concern over introducing a toxic chemical in the water, the design of the disinfection process is increasingly leaning toward technologies that destroy the pathogens while balancing the effects of this disinfected wastewater on the population of aquatic biota or a drinking water supply. Since ultraviolet (UV) irradiation is not a chemical additive, it does not leave or produce any by-product toxic compounds in the wastewater, like traditional chlorination and de-chlorination processes do. Therefore, the use of UV does not affect a drinking water supply or the aquatic biota in receiving waters. Life cycle assessment or analysis (LCA) is used to quantify the environmental benefits of using UV disinfection technology (as well as better protecting public health), instead of chlorination and de-chlorination methods. LCA tools are being used to evaluate the short and long term environmental effects of both processes, and to select the best sustainable process. The approach here combines environmental LCA with these disinfection processes incorporating economic criteria and all aspects of the environment: chemical use, electricity use, and releases to water, air, and land. The environmental, health, and economic benefits and other effects show the greater sustainability of UV technology (a "clean" ecological disinfection process) in comparison to that of traditional disinfection with chlorine. Electronic Publication     

A new fast heuristic for labeling points

In the point site labeling problem, we are given a set P={p₁,p₂,…,pn} of point sites in the plane. The label of a point pi is an axis-parallel rectangle of specified size. The objective is to label the maximum number of points on the map so that the placed labels are mutually non-overlapping. Here, we investigate a special class of the point site labeling problem where (i) height of the labels of all the points are same but their lengths may differ, (ii) the label of a point pi touches the point at one of its four corners, and (iii) the label of one point does not obscure any other point in P. We describe an efficient heuristic algorithm for this problem which runs in time in the worst case. We run our algorithm as well as the algorithm Rules proposed by Wagner et al. on randomly generated point sets and on the available benchmarks. The results produced by our algorithm are almost the same as Rules in most of the cases. But our algorithm is faster than Rules in dense instance. We have also computed the optimum solutions for all the examples we have considered by designing an algorithm, which performs an exhaustive search in the worst case. We found that the exhaustive search algorithm runs reasonably fast for most of the examples we have considered.     

A Generalization of Magic Squares with Applications to Digital Halftoning

A semimagic square of order n is an n×n matrix containing the integers 0,…,n ²−1 arranged in such a way that each row and column add up to the same value. We generalize this notion to that of a zero k×k -discrepancy matrix by replacing the requirement that the sum of each row and each column be the same by that of requiring that the sum of the entries in each k×k square contiguous submatrix be the same. We show that such matrices exist if k and n are both even, and do not if k and n are relatively prime. Further, the existence is also guaranteed whenever n=k ^m , for some integers k,m≥2. We present a space-efficient algorithm for constructing such a matrix. Another class that we call constant-gap matrices arises in this construction. We give a characterization of such matrices. An application to digital halftoning is also mentioned. A preliminary version of this paper appeared in Proceedings of International Symposium on Algorithms and Computation, Hong Kong, December, 2004. Part of the work on the paper has been carried out when B.A. was visiting JAIST. Work of B.A. on this paper was supported in part by NSF ITR Grant CCR-00-81964. Work of T.A. was partially supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (B).