pH Value Of Medium Research Articles

Selection of Optimal Conditions for Cultivation of Bacillus megaterium UCM B-5710 – Producer of Keratinase

Every year the volume of production of poultry products all over the world is growing steadily. This contributes to a constant increase in the amount of by-products of poultry processing in the form of down and feather waste, which are dangerous for the environment due to the hard-to-degrade keratin protein and a large number of microbial pathogens. Therefore, the use of environmentally friendly methods for the destruction of keratin substrates due to keratinases of microorganisms is an urgent area of research. The aim of this work was to select the optimal cultivation conditions for the Bacillus megaterium strain UCM B-5710 to increase the activity of the keratinase synthesized by it. Methods. The culture was grown at 28°C, 201 rpm for 7 days on a basic nutrient medium containing defatted chicken feathers as the only source of carbon and nitrogen. The selection of optimal cultivation conditions was carried out according to the following parameters: temperature (21°C, 28°C, 42°C), stirring speed (201 rpm, 212 rpm), amount of inoculum (5%, 10%, 15% , 20%, 25%), the initial pH value of the nutrient medium (4.0–11.0), concentration of keratin-containing substrate (0.1%, 0.2%, 0.5%, 1.0%, 1.5%, 2.0%), additional carbon source (glucose, galactose, lactose, maltose, sucrose, mannitol, potato and corn starch, soluble starch, soybean meal) and nitrogen (NH4Cl, NH4NO3, (NH4)2SO4, NaNO3, urea, peptone, tryptone, yeast extract and soybean meal) at a concentration of 1%. Keratinase activity was assessed by the UV absorption at 280 nm of the hydrolysis products of keratin-containing raw materials. Protein was determined by the Lowry method. Results. The dynamics of the enzyme synthesis showed that the culture of B. megaterium UCM B-5710 exhibited the highest keratinase activity on the 3rd day, and complete splitting of feathers was observed on the 4–5th days. The selection of the concentration of the keratin-containing substrate showed that 0.5% is the optimal concentration. The study of the influence of the initial pH value of the nutrient medium indicates that the culture grew well at pH 6.0–7.0 and pH 9.0–11.0, but at pH 8.0 its growth was very weak. The culture exhibited the maximum keratinase activity at pH 10.0. In addition, at this pH value, complete splitting of feathers was visually observed. The influence of such a key factor as temperature on the growth and synthesis of the enzyme by B. megaterium UCM B-5710 culture demonstrated complete splitting of feathers already on the 2nd day of cultivation at 42°C, at 21°C the culture split feathers very poorly. The introduction of the inoculum into the composition of the nutrient medium in an amount of 15% of the volume of the medium and the mixing intensity of 212 rpm turned out to be optimal. Besides, it was shown that the introduction of an additional source of carbon or nitrogen had an ambiguous effect on the level of keratinase activity of B. megaterium UCM B-5710. Complete inhibition of enzyme synthesis was observed when ammonium sulfate was added to the nutrient medium, and partial inhibition was observed in the case of glucose, lactose, and maltose. Potato, corn, and soluble starch stimulated keratinase synthesis. The majority of inorganic nitrogen sources (ammonium chloride and nitrate) did not affect the synthesis of B. megaterium UCM B-5710 keratinase, while organic sources (urea, peptone, tryptone, yeast extract) increased the level of keratinase activity by 20–50%. However, the most effective result was obtained using soybean meal, the addition of which to the nutrient medium increased the keratinase activity by 2.5 times. Conclusions. As a result of the studies, the optimal conditions for cultivation of the B. megaterium UCM B-5710 strain were selected: the optimum temperature for the growth and development of the culture is 42°C, the initial pH value is 10.0, the stirring speed is 212 rpm and the amount of inoculum introduced is 15%, an additional source of carbon and nitrogen in the form of soybean meal at a concentration of 0.5%. This made it possible to increase the activity of keratinase by 4 times.

GENETIC ENGINEERING OF STRAIN ESCHERICHIA COLI BL21.BT1 CAPABLE TO SYNTHESIZE RECOMBINANT BETA-1,3-NACETYLGLUCOSAMINE TRANSFERASE

A strain of Escherichia coli BL21.Bt1, a producer of the recombinant beta-1,3-N-acetylglucosamine transferase Bacillus thuringiensis BIM B-180, has been constructed. The cultivation conditions of the producer strain are optimized: the initial pH value of the nutrient medium is 7.2; cultivation temperature after induction – 20 °C; constant stirring at an intensity of 200 rpm; the use of 1 mM isopropyl-β-D-1-thiogalactopyranoside as an inducer; introduction of 10 mM lactose 3 h after induction.
 It was shown that the yield of the target enzymatic protein after 24 h of cultivation of the E. coli BL21.Bt1 strain under optimized conditions reaches 63 μg/ml.

Mechanism of Sand Cementation with an Efficient Method of Microbial-Induced Calcite Precipitation.

This paper presents an efficient method of microbial-induced calcite precipitation (MICP) for cementation of sand particles. First, the influence of initial pH value of the culture medium on the growth of bacteria was discussed. Then, the compressive strength and calcium carbonate content of cemented sand columns with different sand particle sizes were measured to indicate the cementation effectiveness. The microstructure of cemented sand columns as well as the mineral composition and distribution of calcium carbonate were characterised by means of scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) and X-ray diffraction (XRD). The results showed that the urease-producing bacteria S. pasteurii can be cultured at the initial pH values of 7–10, while a higher pH (e.g., 11) would hinder its growth and decrease its urease activity. The injection method of MICP with high standing time can cement sand columns effectively. Small average sand particle size of sand columns and high injection cycles can facilitate the gain of compressive strength, while calcium carbonate content of sand column higher than 8% can promote the increase of compressive strength. XRD results indicate that the fine grains generated on the surface of sand particles are calcite. The distribution of calcite on sand particles’ surface is broad and uniform. First, calcite was precipitated on the surface of sand particles, and then a precipitation layer was formed, which would connect sand particles through its high enough thickness and contribute to the development of compressive strength of the whole sand column.

Electrochemical Corrosion Behavior of Laser Welded 2205 Duplex Stainless-Steel in Artificial Seawater Environment under Different Acidity and Alkalinity Conditions

The electrochemical corrosion behavior of laser welded 2205 duplex stainless-steel in artificial seawater environment (3.5% NaCl solutions) with different acidity and alkalinity conditions (different pH values) was investigated using different techniques. Namely, capacitance measurements (Mott–Schottky approach), electrochemical impedance spectroscopy and potentiodynamic polarization measurements. The formation of pitting corrosion on the exposure surfaces of the tested duplex stainless-steel samples was investigated and confirmed by characterizing the surface morphology using field emission scanning electron microscope (FE-SEM). Based on the obtained results, a proportional relation has been found between pH value of the solution medium and the generated film resistance due to the processes of charge transfer, which directly affecting the pitting formation and its specifications. Since the film layer composition created on the duplex stainless-steel surface is changes depending on the pH value, it was found that different bilayer structure type was generated according to the acidity or alkalinity level. The presented bilayer is almost composed from metal oxides, such as iron oxide and chromium oxide, as confirmed by Raman Spectroscopy technique. As the pits size and its quantity increased with decreasing pH value, it can be concluded that the corrosion resistance property of the laser welded 2205 duplex stainless-steel sample is improved on the alkalinity direction of the solution. Vice versa, higher acidic solution has more ability for corrosion.

L-Asparaginase-Based Biosensors

L-asparaginase (ASNase) is an aminohydrolase enzyme widely used in the pharmaceutical and food industries. Although currently its main applications are focused on the treatment of lymphoproliferative disorders such as acute lymphoblastic leukemia (ALL) and acrylamide reduction in starch-rich foods cooked at temperatures above 100 °C, its use as a biosensor in the detection and monitoring of L-asparagine levels is of high relevance. ASNase-based biosensors are a promising and innovative technology, mostly based on colorimetric detection since the mechanism of action of ASNase is the catalysis of the L-asparagine hydrolysis, which releases L-aspartic acid and ammonium ions, promoting a medium pH value change followed by color variation. ASNase biosensing systems prove their potential for L-asparagine monitoring in ALL patients, along with L-asparagine concentration analysis in foods, due to their simplicity and fast response.

Synthesis of poly(styrene‐co‐allylamine)‐b‐poly(2‐(dimethylamino)ethyl methacrylate) graft copolymers via “grafting from” atom transfer radical polymerization and their self‐assembly in aqueous media

AbstractIn this work, we report a new synthetic scheme for synthesis of graft copolymers. At first, poly(styrene‐co‐acrylonitrile) copolymers with different molecular weights were synthesized via atom transfer radical polymerization (ATRP). Then, lithium aluminum hydride was used as reducing catalyst of nitrile groups to obtain poly(styrene‐co‐allylamine) copolymers. Amine groups of poly(styrene‐co‐allylamine) copolymers were reacted to 2‐bromo‐2‐methylpropionyl bromide (BiBB) to yield poly(styrene‐co‐N‐allyl‐2‐bromo‐2‐methylpropanamide) (poly(styrene‐co‐NABMPA)) as macroinitiator for “grafting from” ATRP. Then, ATRP of 2‐(dimethylamino)ethyl methacrylate (DMAEMA) was performed to graft PDMAEMA side chains. Finally, self‐assembly behavior of synthesized graft copolymers was investigated in aqueous media with different pH values and morphology of obtained supramolecular structures was studied. Synthesized copolymers were well‐characterized by 1H NMR, 13C NMR, and gel permeation chromatography. Also, morphology of self‐assembled structures was studied by FE‐SEM images whereas dynamic light scattering was utilized to measure particle size and particle size distribution. Results showed that morphology of self‐assembled supramolecular structures depended on molecular weight of backbone and pH value of media. By changing the self‐assembly conditions, different morphologies including spherical, Janus, and interconnected Janus were obtained.

Application of starch nanoparticles as a stabilizer for Pickering emulsions: Effect of environmental factors and approach for enhancing its storage stability

To apply starch nanoparticles (SNPs) as a Pickering emulsion stabilizers, effect of environmental factors (pH and ionic strength) on the characteristics of SNPs was evaluated. The SNPs were characterized by zeta-potential measurement, dynamic light scattering, and transmission electron microscopy (TEM). As the pH value (from 4 to 10) of medium decreased or NaCl concentration (from 0 to 60 mM) of medium increased, the hydrodynamic mean diameter of SNPs was increased. The TEM results revealed that the larger hydrodynamic mean diameter of SNPs resulted from aggregation of SNPs. Higher SNPs content decrease the droplet size of the Pickering emulsion and, it is thought that SNPs content higher than 5% may be required to produce a stable emulsion with 10% oil content. Oiling-off on top of the emulsion clearly appeared at higher pH conditions. Stability of the emulsion was enhanced as pH decreased, and oiling-off was not observed during the storage at pH 3. Addition of chitosan (>0.4%) enhanced the stability of the emulsion without any oiling-off and creaming during the storage at pH 7. Confocal laser scanning microscopy revealed that chitosan may form a stable solid layer with SNPs surrounding the emulsion, which may enhance stability of the emulsion. The findings in this study suggested a useful information and approach for application of SNPs as Pickering emulsion stabilizers in various industries.

Immobilization of lipase by dialdehyde cellulose crosslinked magnetic nanoparticles

Cellulose microcrystalline (MCC) was widely used in pharmaceutical and chemical industries because of its low degree of polymerization and large specific surface area. As its modified form, dialdehyde cellulose (DAC) was used for cross-linking and immobilizing Rhizopus lipase together with magnetic nanoparticles (MNPs) due to its active aldehyde groups.In this study, in order to maintain the original enzyme activity as much as possible and improve the stability of lipase, the Rhizopus lipase was successfully immobilized on the magnetic dialdehyde cellulose nanoparticles (MDC). Specifically, the immobilization conditions including dosage of DAC, concentration of enzyme, immobilization time and temperature together with pH value of the reaction medium were optimized. Maximum immobilization yield (60.03 ± 0.49%) and recovery activity (88.88 ± 0.61%) can be obtained under the optimal process conditions. The changes in secondary structures of immobilized enzyme revealed the increment in conformational rigidity, which can be reflected in temperature and pH stability as well as tolerance of organic reagents. Additionally, the recovery activity of immobilized enzyme still reached 50.60 ± 0.59% after 30 d of storage and 52.10 ± 0.57% retained after 6 cycles. These results indicated the ideal application prospect of MDC in immobilized enzymes.

A pH-sensitive curcumin loaded microemulsion-filled alginate and porous starch composite gels: Characterization, in vitro release kinetics and biological activity

To improve the controlled release and stability of the loaded drug, the alginate–porous starch solution, as the gel matrix (GM), was prepared and added into curcumin-loaded microemulsion (CUR-ME) in a certain proportion, and then mixed with slow-gelling agents (CaCO3 + d-glucono-δ-lactone) to prepared curcumin-loaded microemulsion gel (CUR-ME-G). With increasing the proportion of GM from 25% (CUR-ME3G1) to 83% (CUR-ME1G5), the drug loading efficiency increased from 24% to 98% and the maximum drug loading capacity (14.9 mg/g) was found in CUR-ME1G3 with 75% GM. Moreover, a denser structure that entrapped all microemulsion droplets was formed with increasing the proportion of microemulsion according to the observation of scanning electron microscopy. This was also confirmed by Fourier transform infrared spectroscopy and Raman spectroscopy that no new peaks appeared in CUR-ME-G, while the hydrogen bonding interactions might exist between curcumin and sodium alginate. The in vitro release of the CUR-ME-G followed diffusion-controlled mechanism that was consistent with the first-order kinetic model. The release rate depended on the components of the CUR-ME-G and the pH value of the release medium. CUR-ME-G with curcumin concentration of 0.20% exhibited the best biological activity. CUR-ME-G might provide a potential application in the smart drug delivery systems.

Intrinsic hydroquinone-functionalized aggregation-induced emission core shows redox and pH sensitivity

Aggregation-induced emission (AIE) fluorophores exhibit strong fluorescence in an aggregated state but emit no or weak fluorescence in dilute solutions. This emerging class of AIE optical materials comprise a variety of functionalities. Here an AIE luminescence core, 1-hydroquinol-1,2,2-triphenylethene (HQTPE), has been designed and synthesized. This AIE core is simple but is fundamentally important to chemistry because of its intrinsic redox and pH activities. The incorporation of hydroquinone (HQ) moiety into a common AIE core tetraphenylethene (TPE) yields HQTPE with unique fluorescent properties like nonlinear self-quenching over most other AIE-active fluorophores (AIEgens) so far reported. There are differences of photochemical properties between HQTPE, 1-benzoquinol-1,2,2-triphenylethene (QTPE, the oxidized counterpart) and its anions. Interestingly, as the solution concentration is increased, AIEgen HQTPE shows stronger fluorescence but QTPE exhibits rapid quenching of fluorescence in a nonlinear fashion, which are in agreement with theoretical studies. The fluorescence of HQTPE is also highly dependent on the pH value of media. We have further explored HQTPE as an ultrasensitive redox probe and efficient deoxidizer, which could lead to potential applications in health care, food security, environmental monitoring, optic and electronic devices.

Synthesis, characterization, anti-inflammatory and anti-Helicobacter pylori activities of novel benzophenone tetracarboxylimide benzoyl thiourea cross-linked chitosan hydrogels

Chitosan (Cs) was cross-linked with four various quantities of 4,4′-(5,5′‑carbonylbis(1,3-dioxoisoindoline-5,2-diyl))dibenzoyl isothiocyanate. Elemental analysis, FTIR and 1H NMR spectroscopy assured that the amino groups of chitosan reacted with the isothiocyanate groups of the cross-linker producing four new hydrogels namely as BBTU-Cs-1, BBTU-Cs-2, BBTU-Cs-3, and BBTU-Cs-4 according to the increment of their cross-linking content, respectively. SEM showed their porous structures and XRD indicated their amorphous nature. Their swell ability increased with decreasing the medium pH value and with increasing cross-linking density. In comparison with the popular COX inhibitor Celecoxib, these hydrogels showed an inhibition activity towards COX enzymes with selective inhibition towards COX-2. Their inhibition activity could be arranged as follows: Celecoxib > BBTU-Cs-4 > BBTU-Cs-3 > BBTU-Cs-2 > BBTU-Cs-1. BBTU-CS-4 hydrogel exhibited a potent inhibition against COX-2 (IC50 0.42 μg/ml) compared with that observed for the standard Celecoxib (IC50 0.26 μg/ml). BBTU-Cs-4 is more potent against H. pylori compared to the other hydrogels. BBTU-Cs-4 at a concentration of 7.81 μg/ml is able to kill 100% of the H. pylori and exhibits a preferential ability to inhibit 89.35% of COX-2 than COX-1 (0%). These findings make BBTU-Cs-4 a promising anti-H. pylori and selective anti-inflammatory agent.

Microalgal photosynthesis induces alkalization of aquatic environment as a result of H+ uptake independently from CO2 concentration – New perspectives for environmental applications

The photosynthetic process in microalgae and the extracellular proton environment interact with each other. The photosynthetic process in microalgae induces a pH increase in the aquatic environment as a result of cellular protons uptake rather than as an effect of CO2 consumption. The photosynthetic water photolysis and the reduction/oxidation cycle of the plastoquinone pool provide lumen with protons. Weak bases act as “permeant buffers” in lumen during the photosynthetic procedure, converting the ΔpH to Δψ. This is possibly the main reason for continuous light-driven proton uptake from the aquatic environment through cytosol and stroma, into the lumen. The proton uptake rate and, therefore, the microalgal growth is proportional to the light intensity, cell concentration, and extracellular proton concentration. The low pH in microalgae cultures, without limitation factors related to light and nutrients, strongly induces photosynthesis (and proton uptake) and, consequently, growth. In contrast, the mitochondrial respiratory process, in the absence of photosynthetic activity, does not substantially alter the culture pH. Only after intensification of the respiratory process, using exogenous glucose supply leads to significantly reduced pH values in the culture medium, almost exclusively through proton output. Enhanced dissolution of atmospheric CO2 in water causes the phenomenon of ocean acidification, which prevents the process of calcification, a significant process for numerous phytoplankton and zooplankton organisms, as well for corals. The proposed interaction between microalgal photosynthetic activity and proton concentration in the aquatic environment, independently from the CO2 concentration, paves the way for new innovative management strategies for reversing the ocean acidification.

Effect of Electrode Material on the Removal of Industrial Oil and Soap Wastewater Using Electrocoagulation Process

Treatment of oil and soap industrial wastewater using aluminum and iron electrode material has been investigated in this study to compare for each electrode, the performance of the electrocoagulation process. The effectiveness of relevant industrial wastewater characteristics such as the chemical oxygen demand (COD) and oil-grease removal effects of major operating parameters such as medium pH value, electrode material, and current density, and running time and energy consumption were studied. All experiments were done in an electrocoagulation cell with an effective volume of 500 mg/ liters. Under the same operating conditions, it was observed that aluminum electrodes have higher efficiency of removal than iron electrodes. COD and O&G removal efficiencies of 94.93%, 90.20% and 27.49%, 13.27% were observed for aluminum and iron electrode in a special case with optimum initial pH value, maximum current density, time, and initial COD concentration equal to 3, 73.33 A/m2, 30 min, 19750 mg/l, respectively. The electrode energy consumptions for each electrode material have been calculated to be 1.68, 3.04 KWh/kg COD for Aluminum and iron respectively at 15 volts. It can be concluded that the electrocoagulation process using aluminum electrodes is efficient for COD and O&G removal from industrial wastewater

In vitro fermentation characteristics of polysaccharide from Sargassum fusiforme and its modulation effects on gut microbiota

In this study, polysaccharides from Sargassum fusiforme (SFP) were obtained by cellulase assisted hot water extraction. The chemical composition, structural characteristics, and in vitro fermentation properties of SFP were investigated. Results showed that the contents of total carbohydrate, protein, uronic acid and sulfate in SFP were 83.25%, 1.42%, 12.80% and 7.81%, respectively. It mainly consisted of fucose glucose and galactose, with molecular weight of 255.83 kDa. UV spectrum, FTIR, SEM and AFM results showed that SFP was a typical sulfate polysaccharide with relative smooth surface and regular shape. After in vitro fermentation for 24 h, the pH value of fermentation medium declined significantly (p < 0.05), utilization of carbohydrate was 53.17%. The contents of total SCFAs increased by 10.77 times. Moreover, SFP fermentation could change obviously the microbiota composition. It significantly increased the abundance of Faecalibacterium (increased by 49.07% compared with the Blank24 group), Phascolarctobacterium (increased by 88.06%), Bifidobacterium (increased by 139.13%), Ruminococcaceae_UCG-014 (increased by 177.78%), and Lactobacillus (increased by 400.00%), decreased the abundance of Prevotella_9 (decreased by 34.54%) and Blautia (decreased by 40.79%) at genus level. These results showed that SFP could be utilized by microbiota in human feces, and may have the potential to improve intestinal health.

Study on the influencing factors and mechanism of calcium carbonate precipitation induced by urease bacteria

Microbial induced calcium carbonate precipitation (MICP) is a widespread phenomenon in nature. In this paper, various factors affecting microbial growth and urease activity were studied, including temperature, initial pH, urea concentration, Ca2+ concentration and gelling solution concentration, and the optimal process conditions for calcium carbonate preparation were determined. Subsequently, the changes of Ca2+ concentration, NH4+ concentration and pH value in alkaline medium with and without bacteria were studied carefully, and the dynamic process of calcium carbonate deposition was also revealed. Finally, the mineralization mechanism model of MICP was established by characterization and analysis of the precipitates. The results indicated that urease produced by bacteria in the metabolism process of bacteria could accelerate the hydrolysis rate of urea and the formation rate of carbonate. In addition, the bacterial cells themselves were negatively charged, which could adsorb Ca2+ with positive charge. Meanwhile, they could also be used as the nucleation sites to accelerate the generation of calcium carbonate.

Lactobacillus rhamnosus and Lactobacillus casei Affect Various Stages of Gardnerella Species Biofilm Formation.

Bacterial vaginosis (BV) and its recurrence are most commonly associated with the formation of Gardnerella species biofilm. Probiotics are typically used to treat BV; however, the optimal period of Lactobacillus probiotic application in BV treatment remains uncertain. The present study aimed to explore the effects of Lactobacillus rhamnosus and Lactobacillus casei on various stages of biofilm formation in Gardnerella species. The biofilm-forming ability of seven strains, including one Gardnerella vaginalis ATCC 14018 and six clinically isolated Gardnerella species, was determined via gentian violet staining assay. Moreover, the sensitivity of the planktonic and biofilm forms toward metronidazole and clindamycin was assessed via microdilution broth method. L. rhamnosus Xbb-LR-1 and L. casei Xbb-LC-1 were added during various stages of biofilm formation in Gardnerella species and were cocultured for 24 h. The biofilm thickness of each sample was determined via confocal laser scanning microscopy (CLSM). The absolute quantities of Gardnerella species in each sample was obtained via real time polymerase chain reaction method, and the pH value was obtained using a pH indicator paper. Biofilm formation by Gardnerella species in a medium with distinct pH values was observed via gentian violet staining, CLSM, and scanning electron microscopy (SEM). The biofilm increased the resistance of Gardnerella species toward metronidazole and clindamycin. L. rhamnosus added at the initial biofilm formation stage in Gardnerella species exhibited highest inhibitory effect, with a percentage inhibition of 38.17% ± 1.35%. When the pH value of the culture medium was <4.5 or >6.5, ATCC 14018 could hardly form a biofilm; however, at pH ≥4.5 and ≤6.5, it was able to form a stronger biofilm. The amount of biofilm attained maximum value at optical density of 3.29 ± 0.28 (595 nm), pH 5.5, and at 36 h. Biofilm formation increases the resistance of Gardnerella species toward antibiotics. Maintaining an acidic vaginal environment with pH <4.5 and a vaginal microbiota dominated by Lactobacillus remarkably prevents the formation of Gardnerella species biofilm at the initial stage, which further has a significant impact on the treatment and prevention of biofilm-related infections.

Response surface methodology as an approach for optimization of α-amylase production by the new isolated thermotolerant Bacillus licheniformis WF67 strain in submerged fermentation

Abstract In this study, a thermo-tolerant isolated Bacillus licheniformis WF67 has produced considerable levels from the extracellular α-amylase under submerged fermentation conditions. To maximize the α-amylase production, both traditional “one factor per time” and statistical optimization were performed. The “one factor per time” optimization technique declared the most effective parameters in the process of α-amylase production. Those parameters were cultivation medium pH value, incubation time, soluble starch and beef extract as carbon and nitrogen sources. Response surface methodology (RSM) was employed to get the effective values of those most efficient parameters via different interaction ratios between all of them. Central composite design (CCD) was based on the following values: medium pH (pH 3.0–9.0), incubation time (15–75 h), soluble starch (1.5–19.5 g/L), and beef extract (1.0–13 g/L). Results obtained from CCD approach revealed that the incubation of B. licheniformis WF67 for 50 h, at pH value of 6.33, using the specified medium containing 12.55 g/L soluble starch, and 8.31 g/L beef extract were the optimum values for α-amylase production. Under the previously mentioned conditions α-amylase productivity was improved by about 90% (6.633 U/mL) in comparison to the traditional “one factor per time” optimization results (3.486 U/mL).

Evaluation of optimum dosage in blended self curing concrete on the impact of supplementary cementitious materials (scm’s) and durability studies on different proportions

Now a days, the shortage of potable water increases, for domestic and commercial purposes due to environmental conditions. Due to this scarcity, curing of concrete is affected and in this point of view water assets are more valuable every day and becomes more economical. Traditional Curing used for retaining moisture within the concrete elements during the early days and beyond to develop the desired properties in terms of strength & durability. To develop the modern era curing, a few of self-curing agents like Super Absorbent Polymers, Polyethylene Glycol (PEG 400) has been used for internal curing of concrete used for reducing the hydration process. In this experimental study, Supplementary Cementitious Materials like Class F Flyash, Silica Fume and Ground Granulated Blast Furnace Slag (GGBFS), have been casted for 65%+25%+15% (M2), 65%+20%+15% (M6), 65%+25%+10% (M10) and 65%+20%+15% (M11) of optimal mix proportions. The sorptivity assessments have being carried out on all blended mixes of Self Cured Concrete with size of 15 cm x 15cm x15cm. The pH value of the acidic medium was at 0.45 by submerging in acid, the specimen samples are brought out and were cleaned in repeatedly with water and kept in atmospheric condition for two days for constant weight and then the specimens are balanced using weighing scale and loss in weight and hence the percentage in loss of weight was premeditated within and after 28 days with different mix proportion of M30 grade of concrete supplementary cementitious materials like Flyash, Ground Granulated Blast Furnace Slag and Silica Fume with PEG 400 as 1% by its weight.

Preparation of dimethylaminopropyl octadecanamide/stearic acid vesicles incorporating azobenzene and their UV-responsive release property

UV-responsive vesicle was prepared by incorporating azobenzene in the vesicular membrane composed of dimethylaminopropyl octadecanamide (DMAPODA) and stearic acid (SA). Azobenzene intercalated in the vesicular membrane underwent cis-to-trans isomerization under the UV irradiation, confirmed by UV spectroscopy. The phase transition temperature of vesicle was found to be around 51.2 °C by differential scanning calorimetry. Using a negative staining technique, the vesicles were found as circular and irregular-shaped particles on the TEM photo. The mean hydrodynamic diameter of vesicles increased from 199.4 to 1597.3 nm when the lipid/azobenzene ratio increased from 100/0 to 100/5. The zeta potential of DMAPODA/SA vesicle decreased from about + 60 mV to – 60 mV when the pH value of medium increased from 3.0 to 10.0, and the inclusion of azobenzene in the vesicular membrane had little effect on the zeta potential. UV irradiation markedly promoted the release of carboxylic fluorescein loaded in vesicle incorporating azobenzene, possibly because the cis-to-trans photoisomerization would disturb the well-ordered crystalline structure of the vesicular membrane.

Hydroxyapatite of plate-like morphology obtained by low temperature hydrothermal synthesis

The morphology of hydroxyapatite crystals formed in hydrothermal reaction of calcium EDTA complex with KH2PO4 at 120 °C depends on the pH value of the reaction medium. Bone-like platy microcrystals were prepared at pH 6, while at higher pH values rod-like species were obtained.