Litter decomposition in terrestrial ecosystems has a major role in the biogeochemical cycling of elements in the environment. Climatic features, like temperature, rainfall, humidity, and seasonal ...variations affect the rate of litter decomposition. This review attempts to understand the litter decomposition process in tropical forest ecosystems. It also reviews the influence of various factors on litter degradation and techniques used for assessing leaf litter decomposition. It is observed that very few studies were conducted on litter decomposition in forest ecosystems, such as tropical and temperate forests. Hence, comprehensive studies on litter degradation have to be undertaken in order to understand the turnover rate of nutrients and other elements in these sensitive ecosystems.
Denitrification of high strength nitrate wastewater was investigated in granular sludge sequencing batch reactors (SBRs) with the objective of optimizing electron donor requirement, in terms of ...acetate-carbon to nitrate-nitrogen (C/N) ratio. Three SBRs of each 6L working volume were inoculated with activated sludge and operated in parallel at C/N ratios of 1.5, 2 and 3. Formation of denitrifying granular sludge was observed in all the three SBRs. Complete and stable denitrification of feed containing nitrate up to 5420mgL−1 NO3-N was achieved in 24h cycle period for all three C/N ratios studied. However, time for complete denitrification and maximum amount of nitrite accumulation, increased with an increase in C/N ratio. Thus, C/N ratio of 1.5 was found to be optimum for denitrification of high-strength nitrate wastewaters, with acetate as the carbon source. The studies indicate that denitrification in SBRs using granular biomass and acetate as carbon source was highly efficient for denitrification of high strength nitrates.
Nitrate containing acidic wastewaters are generated in nuclear fuel cycle operations. These waters are often neutralized prior to either storage or biological treatment. In this study, treatment of ...high strength nitrate bearing acidic waters was investigated in a sequencing batch reactor. A six liter reactor was inoculated with activated sludge and operated in sequencing batch reactor mode by feeding simulated nitrate wastewater at pH 7.5. After establishing denitrifying microbial consortia in the form of compact granules, the pH of the feed was gradually decreased to 5.0 and then to 4.0. The in situ neutralization of the feed in the reactor by the denitrification-driven alkalinity and the acclimatization strategy helped to achieve complete and stable denitrification during long term operation. The denitrifying microbial community developed in the sequencing batch reactor predominantly consisted of rod- and cocci-shaped microorganisms. This study showed that nitrate bearing acidic effluents can be directly denitrified in granular sludge sequencing batch reactors without a prior treatment. Thus, in situ neutralization and acclimatization strategy can be a potential approach to be considered for treating nitrate contaminated acidic waters.
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•Granular sludge was cultivated for denitrification of high strength nitrate.•Efficient and stable denitrification of 3 g l−1 nitrate at low pH values of 5.0 and 4.0.•Denitrification generated alkalinity for in situ neutralization of low pH waters in sequencing batch reactors.•Acclimation of microorganisms improved denitrification of acidic nitrate waters.
Digital speckle pattern interferometry (DSPI) and digital shearography (DS) are well known optical tools for qualitative as well as quantitative measurements of displacement components and its ...derivatives of engineering structures subjected either static or dynamic load. Spatial phase shifting (SPS) technique is useful for extracting quantitative displacement data from the system with only two frames. Optical configurations for DSPI and DS with a double aperture mask in front of the imaging lens for spatial phase shifting are proposed in this paper for the measurement of out-of-plane displacement and its first order derivative (slope) respectively. An error compensating four-phase step algorithm is used for quantitative fringe analysis.
In the present study, the composites made from chopping prepregs in rectangular chips, called discontinuous composites derived from chopped prepreg (DCCP) were modeled for stiffness prediction. ...Standard mechanics approach with displacement boundary conditions is used for stiffness prediction. The minimum size of the representative volume element (RVE) for this material is determined. An algorithm based on the random sequential adsorption technique (RSA) has been exploited to generate the 3D RVEs. RVEs of five different aspect ratios of the cuboid-shaped inclusions are developed using this technique. The chips are completely randomly oriented with a constant volume fraction. A detailed study was carried out in each case by further generating the RVEs with different increasing sizes, and the smallest size of RVE with geometric periodicity was identified. Further, the characteristics of these RVEs have been investigated for different aspect ratios, varying the chip volume fraction for the influence of volume fraction on RVE size and the material properties. The efficacy of the developed approach is demonstrated through repetitiveness of the effective properties prediction for various scenarios studied. The resulting material showed isotropy in the plane where chips are distributed randomly while overall isotropy about 80% is seen in most of the RVEs studied.
Structural and motional features in the denatured state of a protein dictate the early folding events starting from that state and these features vary depending upon the nature of the denaturant ...used. Here, we have attempted to decipher the early events in the folding of Dynein Light Chain protein (DLC8), starting from DMSO-d6 denatured state. Multinuclear NMR experiments were used to obtain the full spectral assignment. The HSQC spectrum shows the presence of two sets of peaks for the residues Met 1, Ser 2, Arg 4, Ala 11, Met 17, Thr 26, Lys 44, Tyr 50, Asn 51, Trp 54, His 55, Val 58, Gly 59, Ser 64, Tyr 65, His 68, Phe 86, Lys 87 indicating the presence of slow conformational transition in the heterogeneous ensemble. Analysis of residual structural propensities with secondary 13C chemical shifts, 3J(HN−Hα) coupling constants and 1H-1H NOE revealed the presence of local preferences which encompass both native and non-native like structures. The spectral density calculations, as obtained from measured R1, R2 and 1H-15N steady state NOE values provide insights into the backbone dynamics on the milli to picosecond timescale. The segment Ser 14 – His 55 exhibits slow motions on the milli- to microsecond timescale arising from conformational exchange. The presence of native like structural preference, as well as conformational exchange classifies the above segment as the nucleation site of folding. Based on the observations, we propose here, the probable hierarchy of folding of DLC8 on dilution of denaturant: the two helices are formed first followed by the formation of β2 and β5.
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► Residue level characterization of the DMSO-d6 denatured ensemble of DLC8 with NMR. ► Presence of slow conformational exchange in the denatured ensemble. ► Native helical propensities in the segment Ser 14- His 55. ► High conformational exchange in the segments corresponding to native helices. ► Two helices are supposedly formed first during folding followed by β2 and β5.
In laser based interferometry, the unambiguous measurement range is limited to half a wavelength. Multiple wavelength or white light interferometer is used to overcome this difficulty. In this paper ...a white light interferometer with a colour CCD camera is discussed. We access interference intensity information from the three channels of the colour CCD simulating three-wavelength measurement. This makes the data acquisition as simple as in single wavelength interferometry. The unambiguous measurement range however gets limited by the coherence length of the CCD. The usefulness of the proposed method is demonstrated on a micro-sample.
► A white light interferometer system using a single-chip colour CCD for 3-D surface profiling on micro-samples is demonstrated. ► The proposed method makes the data acquisition and phase evaluation procedures as simple as in case of single wavelength method. ► The use of colour CCD camera in white light interferometry makes the measurement faster, simple. ► And cost effective, which is very much useful for industrial applications.
To understand the rules governing the protein folding process it is essential to study the stability and unfolding of small monomeric proteins. Here, I present the pH dependent thermal unfolding ...energetics and conformational stability analysis of monomeric Dynein light chain protein (DLC8) in the pH range 3.5–2.0. DLC8 is the smallest and the most conserved light chain among the light chains of the dynein motor assembly. Thermal unfolding of DLC8 monomer is much complex with the presence of transient intermediates, which is in contrast to the notion that small proteins unfold via simple two-state process. The unfolding seems to be more cooperative at lower pH and the temperature of highest conformational stability (
T
s) is found to be maximum (295.7
K) at pH 2.76. Stability curves have been simulated to understand the thermodynamic parameters that govern the shapes of the experimentally obtained curves. Further, an effort has been made to correlate the observed differences in the denaturation energetics with the protein sequence in order to throw light on the structure-folding paradigm of the DLC8 monomer.
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