This study describes a method of strength improvement of cement–sand mortar by the microbiologically induced mineral precipitation. A thermophilic anaerobic microorganism is incorporated at different ...cell concentrations with the mixing water. The study showed that a 25% increase in 28 day compressive strength of cement mortar was achieved with the addition of about 10
5 cell/ml of mixing water. The strength improvement is due to growth of filler material within the pores of the cement–sand matrix as shown by the scanning electron microscopy. The modification in pore size distribution and total pore volume of cement–sand mortar due to such growth is also noted.
E. coli microorganisms were also used in the cement mortar for comparison, but no improvement in strength was observed.
Aims
Hot springs have always drawn attention due to their unique chemical richness and the presence of different microbial communities. The use of hot spring bacteria in concrete technology is our ...primary focus; isolation of an alkaliphilic bacterium from the Bakreshwar hot springs having longer survival and better efficacy towards cementitious environment was the basis of our study's design.
Methods and Results
A novel facultative anaerobic and highly alkaliphilic bacterial strain (BKH4; GenBank accession no. KX622782) belonging to the family ‘Bacillaceae’ and homologous (99%) with Lysinibacillus fusiformis was isolated from Bakreshwar hot springs. The isolated coccoid‐type Gram‐positive bacterium grows well in a defined semi‐synthetic medium (pH 12·0 and 65°C). This bacterium survives for more than a month and shows better efficacy in enhancing compressive strengths (>50%), ultrasonic pulse velocity (>25%) and durability of the cementitious mortar when incorporated at a concentration of 104 cells per ml of water used.
Conclusion
The novel bacterium BKH4 is more effective for the enhancement of the bioconcrete properties.
Significance and Impact of the Study
BKH4 bacterium will add a new dimension to future concrete technology for its usefulness in strength enhancement and durability due to its alkaliphilic nature and longer survival within a cementitious environment.
Grinding is a multi-point cutting operation. The specific energy or the energy expended for unit material removal in grinding is very high, typically one or two orders higher than the machining ...specific energy. Such high specific energy required in grinding can be attributed to the irregular and random geometry of the abrasive grits, which induce a lot of rubbing and ploughing actions along with the chip formation by shearing process. Also the effective angle in grinding is highly negative which is again responsible for such high-specific energy requirement in grinding. In grinding, a number of notable phenomena occur during the chip formation process, which actually consumes a significant percentage of energy. Such main energy consumers in grinding are:
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Chip formation due to shearing
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Primary rubbing
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Secondary rubbing
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Ploughing
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Wear flat rubbing
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Friction between the loaded chip and workpiece
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Friction between bond and workpiece, etc.
The present paper tries to analytically predict the specific energy consumed during high-efficiency deep grinding (HEDG) of bearing steel by monolayer cBN wheel. During the HEDG process, energy is spent mostly for shearing, rubbing and ploughing processes. The other energy consumers have insignificant role in such high-speed grinding process. So, models which take into account the processes of shearing, primary rubbing, secondary rubbing and ploughing process can reasonably be used to predict the energy requirement in such HEDG process. The total specific energy value obtained from the model has been validated with those experimentally observed values. A good trend matching of the modelled and experimental values have been observed and the root mean square error values have been found to vary between 7% and 11%.
The formation of calcium carbonate (CaCO
) nanoparticles (NPs) in the presence of polystyrene sulfonate (PSS) as an additive was examined by time-resolved small-angle X-ray scattering (SAXS) in a ...flow system that mimics experimental conditions used at home facilities where the precipitation can be achieved in a beaker. The experiments were carried out at low concentrations to remain in the dilute regime. A model-independent analysis was performed using the Porod invariant which defines the scale factor, leaving only the distribution of radii as the adjustable parameter. The presence of the PSS additive strongly retards the precipitation of CaCO
NPs. The formation of NPs reaches a state of equilibrium after a few minutes. Here, it is shown that the concentration of precursors at a fixed PSS concentration plays a key role in determining the size of the NPs obtained. A full analysis of the SAXS patterns was carried out using the Hurd-Flower model to account for the weaker intensity decay than the classical Porod behaviour. The temporal evolution of the particle radii was determined. Wide-angle X-ray scattering experiments carried out simultaneously show that the particles formed have the structure of vaterite with growth consistent with the evolution of the Porod invariant.
The formation of calcium carbonate (CaCO3) nanoparticles (NPs) in the presence of polystyrene sulfonate (PSS) as an additive was examined by time‐resolved small‐angle X‐ray scattering (SAXS) in a ...flow system that mimics experimental conditions used at home facilities where the precipitation can be achieved in a beaker. The experiments were carried out at low concentrations to remain in the dilute regime. A model‐independent analysis was performed using the Porod invariant which defines the scale factor, leaving only the distribution of radii as the adjustable parameter. The presence of the PSS additive strongly retards the precipitation of CaCO3 NPs. The formation of NPs reaches a state of equilibrium after a few minutes. Here, it is shown that the concentration of precursors at a fixed PSS concentration plays a key role in determining the size of the NPs obtained. A full analysis of the SAXS patterns was carried out using the Hurd–Flower model to account for the weaker intensity decay than the classical Porod behaviour. The temporal evolution of the particle radii was determined. Wide‐angle X‐ray scattering experiments carried out simultaneously show that the particles formed have the structure of vaterite with growth consistent with the evolution of the Porod invariant.
The kinetics of precipitation of CaCO3 particles in the presence of polystyrene sulfonate was studied by small‐ and wide‐angle X‐ray scattering. Employment of the Porod invariant and the Hurd–Flower model provides essential information on the kinetics.
Emerging whitefly transmitted begomoviruses are major pathogens of vegetable and fibre crops throughout the world, particularly in tropical and sub-tropical regions. Mutation, pseudorecombination and ...recombination are driving forces for the emergence and evolution of new crop-infecting begomoviruses. Leaf curl disease of field grown radish plants was noticed in Varanasi and Pataudi region of northern India. We have identified and characterized two distinct monopartite begomoviruses and associated beta satellite DNA causing leaf curl disease of radish (Raphanus sativus) in India.
We demonstrate that RaLCD is caused by a complex of two Old World begomoviruses and their associated betasatellites. Radish leaf curl virus-Varanasi is identified as a new recombinant species, Radish leaf curl virus (RaLCV) sharing maximum nucleotide identity of 87.7% with Tomato leaf curl Bangladesh virus-Bangladesh:2 (Accession number AF188481) while the virus causing radish leaf curl disease-Pataudi is an isolate of Croton yellow vein mosaic virus-India (CYVMV-IN) (Accession number AJ507777) sharing 95.8% nucleotide identity. Further, RDP analysis revealed that the RaLCV has a hybrid genome, a putative recombinant between Euphorbia leaf curl virus and Papaya leaf curl virus. Cloned DNA of either RaLCV or CYVMV induced mild leaf curl symptoms in radish plants. However, when these clones (RaLCV or CYVMV) were individually co-inoculated with their associated cloned DNA betasatellite, symptom severity and viral DNA levels were increased in radish plants and induced typical RaLCD symptoms. To further extend these studies, we carried out an investigation of the interaction of these radish-infecting begomoviruses and their associated satellite, with two tomato infecting begomoviruses (Tomato leaf curl Gujarat virus and Tomato leaf curl New Delhi virus). Both of the tomato-infecting begomoviruses showed a contrasting and differential interaction with DNA satellites, not only in the capacity to interact with these molecules but also in the modulation of symptom phenotypes by the satellites.
This is the first report and experimental demonstration of Koch's postulate for begomoviruses associated with radish leaf curl disease. Further observations also provide direct evidence of lateral movement of weed infecting begomovirus in the cultivated crops and the present study also suggests that the exchange of betasatellites with other begomoviruses would create a new disease complex posing a serious threat to crop production.
Nicotine intake through tobacco is very common in female population of lower socioeconomic level who are deprived of healthy diet. Women suffer consequences of smoking such as cardiovascular ...disorder, lung related diseases and oxidative stress, etc. No data are available of the influences of nicotine on lipid profile, lipid peroxidation and antioxidant enzymes levels under restricted dietary protein intake. The present study was carried out to investigate the effect of nicotine on such parameters of female rats fed with protein restricted diet (5% casein) as compared to those with normal protein diet (18% casein) with or without vitamin C or E supplementation.
Subcutaneous injections of nicotine tartrate (3.5 mg/kg body weights per day for 15 days) were given to the rats and subsequent measurements of plasma lipid profile, plasma and ovary lipid peroxidation and antioxidant enzymes were done.
The results showed significant (P<0.01) increase of total cholesterol (TC) and more significant (P<0.001) increase of triglyceride and low-density lipoprotein cholesterol (LDL-C) of plasma under both dietary conditions. The increase of plasma very low-density lipoprotein cholesterol (VLDL-C) was highly significant under protein-restricted diet. The high-density lipoprotein cholesterol (HDLC) decreased significantly in both dietary conditions. Lipid peroxidation in plasma increased significantly in protein-restricted condition. Superoxide dismutase and catalase activities in the ovary tissue decreased significantly (P<0.001) by nicotine treatment in both dietary groups.
Our findings indicated that nicotine-induced toxicity is more in lipid profile (plasma) and lipid peroxidation (plasma and ovary tissue) under protein-restricted diet as compared to that of the normal protein diet. The antioxidant vitamins antagonized the nicotineinduced effects less effectively on the observed parameters under restricted dietary protein.
This paper deals with an investigation of the grindability of Titanium alloy Ti–6Al–4V with monolayered brazed type superabrasive grinding wheels. The experiments, conducted under different grinding ...environments, showed the performance of the grinding fluids based on an evaluation of grinding forces, chip formation and tool condition. It could be found that conventional grinding fluids like oil or alkaline soap are preferable compared to dry or cryogenic conditions or with MoS
2 coated wheels.
Invasive species exert a serious impact on native fauna and flora and have been the target of many eradication and management efforts worldwide. However, a lack of data on population structure and ...history, exacerbated by the recency of many species introductions, limits the efficiency with which such species can be kept at bay. In this study we generated a novel genome of high assembly quality and genotyped 4735 genome-wide single nucleotide polymorphic (SNP) markers from 78 individuals of an invasive population of the Javan Myna Acridotheres javanicus across the island of Singapore. We inferred limited population subdivision at a micro-geographic level, a genetic patch size (~13-14 km) indicative of a pronounced dispersal ability, and barely an increase in effective population size since introduction despite an increase of four to five orders of magnitude in actual population size, suggesting that low population-genetic diversity following a bottleneck has not impeded establishment success. Landscape genomic analyses identified urban features, such as low-rise neighborhoods, that constitute pronounced barriers to gene flow. Based on our data, we consider an approach targeting the complete eradication of Javan Mynas across Singapore to be unfeasible. Instead, a mixed approach of localized mitigation measures taking into account urban geographic features and planning policy may be the most promising avenue to reducing the adverse impacts of this urban pest. Our study demonstrates how genomic methods can directly inform the management and control of invasive species, even in geographically limited datasets with high gene flow rates.
In this study, the fine-scale structure of the diurnal variability of ground-based lightning is systematically compared with satellite-based rain. At the outset, it is shown that tropical variability ...of lightning exhibits a prominent diurnal mode, much like rain. A comparison of the geographical distribution of the timing of the diurnal maximum shows that there is very good agreement between the two observables over continental and coastal regions throughout the tropics. Following this global tropical comparison, we focus on two regions, Borneo and equatorial South America, both of which show the interplay between oceanward and landward propagations of the phase of the diurnal maximum. Over Borneo, both rain and lightning clearly show a climatological cycle of “breathing in” (afternoon to early morning) and “breathing out” (morning to early afternoon). Over the equatorial east coast of South America, landward propagation is noticed in rain and lightning from early afternoon to early morning. Along the Pacific coast of South America, both rain and lightning show oceanward propagation. Though qualitatively consistent, over both regions the propagation is seen to extend further in rainfall. Additionally, given that lightning highlights vigorous convection, the timing of its diurnal maximum often precedes that of rainfall in the convective life cycle.
•A comprehensive comparison of the diurnal cycles of rain and lightning•Focus on coastal propagation of the diurnal cycles using the Island of Borneo and South America as case studies.•The timing of diurnal maximum of lightning precedes that of rain, even though the latter propagates further.
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