Specific Activity Values Research Articles

Characterization of Pectinase Enzyme Produced from Indigenous Yeast Isolates During Fermentation of Robusta Coffee Beans

The following research aims to understand indigenous yeast isolates that are pectinolytic, the effect of incubation time on pectinase enzyme activity, and the pH and temperature properties of pectinase enzymes obtained from indigenous yeasts from spontaneous fermentation of robusta coffee beans. The following type of research is an experiment through RAL (Completely Randomized Design). The results showed that testing of seven indigenous yeast isolates was pectinolytic and that the highest pectinolytic ability was isolate K24I7 with a clear zone diameter of 3.13 mm. The characterization results of the pectinase enzyme produced from isolate K24I7 were optimum at pH 5.5 with an enzyme specific activity value of 10.09 U/mg and optimum temperature in the range of 40oC-60oC with an average enzyme specific activity of 10.08 U/mg. The pectinase enzyme produced from isolate K24I7 is thermophile because it is still active at 70°C

Seasonality of zooplankton active flux in subtropical waters

AbstractThe biological carbon pump (BCP) is the mechanism by which the ocean transports organic matter below the mixed layer, exporting or sequestering it for years to millennia. Physical transport of dissolved and particulate organic carbon, the sinking of particles, and the carbon transported by diel and seasonal vertical migrants are the three main mechanisms of the BCP. In the study of active flux, seasonality is almost unknown and changes in ocean productivity during the annual cycle could promote differences in this transport. Here, we show the results of a cruise performed during spring in the Canary Current System, where we studied zooplankton active flux in two transects from the coastal zone off Northwest Africa toward the ocean. We measured biomass and the enzymatic activity of the electron transfer system (ETS) as a proxy for respiration in the water column down to a depth of 900 m. Compared with a previous survey during fall, we found higher values of specific ETS activity in the mesopelagic zone, promoting a higher active flux. Our results showed that the seasonality of active flux is driven not only by differences in biomass but also by differences in respiration rates in the mesopelagic zone, mainly due to differences in zooplankton body size. A review of the zooplankton active flux values around the Canary Islands showed a fourfold increase during spring compared with other seasons. This small window of higher flux should be considered in models of active carbon export in the ocean.

Engineered nanozyme-cascade catalyzed reaction for rapid acid phosphatase detection

The utilization of artificial multienzyme-catalyzed cascade reactions have greatly benefited biosensors. This study presents a novel nanoreactor consisting of manganese ions-doped hollow carbon nanospheres (Mn@HCNs), which can rapidly transform molecular information into an easily comprehensible colorimetric signal. The Mn@HCNs nanoreactor was utilized to detect acid phosphatase (ACP) within a range of 0.5–10 mU/mL, achieving a limit of detection (LOD) as low as 0.0851 mU/mL. The superiority of our nanoreactor over traditional ACP detection methods stems from its exceptional substrate affinity and the multi-enzymatic behaviors of Mn@HCNs. Especially, the specific POD-like activity (SA) value of Mn@HCNs was superior to most reported Fe3O4 and other single-atom enzymes. Furthermore, this nanoreactor exhibited exceptional selectivity against protein and ion interference, and was furthered to detect ACP in clinical serum samples. The work may extend the development of artificial multienzyme-catalyzed cascade reactions for molecular biosensors and clinical application.

Assessment of Natural Radioactivity in Cements (Local and Imported) in Mali

<i>Background</i>: In this article, the radioactivity concentrations of U-238, Th-232 and K-40 (NORM) and radiological hazard parameters in different types of cements commonly used in Mali and available on the Malian market have been analyzed. The obtained values of NORM concentrations and radiological hazards in seven (07) cements samples will permit to the AMARAP to estimate the exposure (gamma rays) from the buildings and dwellings made by these cements. It will permit also to determine any over exposure (determinist effects which are an immediate tissue reaction due to the high exposition of ionizing radiation) and minimize as well the associated risk due to low doses (stochastic effects). <i>Materials and Methods</i>: The health impact due to the exposure of radionuclides from these cements was evaluated by the determination of specific activity of radionuclides U-238, Th-232 and K-40 using gamma spectrometry analysis. The radiological hazards such as Absorbed Dose Rate (Ḋ) Annual Effective Dose (Ė) Internal and External Dose indexes (H<sub>in</sub> and H<sub>ex</sub>) were evaluated in these cements samples. <i>Results</i>: The range of specific activities for U-238 vary from 21.77 ± 1.50 to 145.31 ± 7.70 Bq/kg, for Th-232 from 8.85 ± 0.52 to 73.56 ± 3.82 Bq/kg and for K-40 from 104.27 ± 5.63 to 351.97 ± 18.08 Bq/kg. The peak of U-238 wasn’t detected only in one (01) sample (CIM04). The highest value of specific activity was reported in sample CIM07 (DANGOTE). The values of radiological hazard such as Ḋ, Ė, H<sub>in</sub> and H<sub>ex</sub> from this work were within the dose criteria limits given by international organizations (ICRP and UNSCEAR) and national standards. <i>Conclusion</i>: This study shows the analyzed cements do not pose any significant source of radiation hazard and are safe for use in the construction of dwellings even if the risk (stochastic effect) associated with low dose exists. Special attention and more analyzes must be done on them for more protection of public health.

Evaluation of Glutathione S-transferases Expression as Biomarkers by Heavy Metals in Geloina expansa from Sepang Besar River, Selangor, Malaysia

Glutathione S-transferases (GSTs) are enzymes involved in phase II of detoxification metabolism and could be used as biomarkers for water pollution. This study aims to determine heavy metal concentrations in the soft tissue of the mangrove clam Geloina expansa, as well as the expression of GSTs in the species. The acid digestion method was used to digest the samples, followed by a standard USEPA 6010B procedure using inductively coupled plasma optical emission spectrometry (ICP-OES) to measure the heavy metal contents in the samples. GST enzyme activity was measured using 1-chloro-2, 4-dinitrobenzene (CDNB) as substrate. One-way ANOVA was performed to compare the mean values of heavy metal concentration, protein concentration, enzyme activity, and specific activity. There was a significant difference (p<0.05) for Zn, total protein, and specific activity in G. expansa, but no significant difference in Pb, Cu and enzyme activity. GST enzyme activities were estimated at 0.16 ± 0.01 µmol/min, with a protein content of 1.24 ± 0.04 mg. The specific activity for GST was 0.13 ± 0.01 µmol/min/mg, calculated as the ratio of enzyme activity to the total protein. GST-specific activity positively correlates with Pb concentration in the soft tissue of G. expansa. Detailed studies on the effects of pollution on the expression of GST need to be further investigated for the future use of this species as an efficient biomarker model.

МИГРАЦИИОННАЯ АКТИВНОСТЬ 137CS В АГРОПРОДУКЦИЮ БИОГЕОЦЕНОЗОВ КРАСНОЯРСКОГО КРАЯ

The purpose of the study is to determine the intensity of 137Cs movement along the trophic chain “soil – diet – livestock products” in the agricultural landscapes of the Krasnoyarsk Region with additional radiation load. A literature review of scientific data characterizing the features of the migration activity of 137Cs in the links “soil – feed – livestock products” in agrobiocenoses with radioactive contamination above established standards is given. Based on the results of a radioecological survey of agricultural landscapes in the central regions of the Krasnoyarsk Region and calculation of absorbed doses, the author identified agricultural landscapes with additional technogenic pollution and determined the specific activity of 137Cs in feed and cow's milk in agricultural landscapes with additional technogenic load. The specific activity values of 137Cs in agricultural landscape feeds with doses of 1.33 and 1.55 mGy/year are higher than the background va¬lue for the Krasnoyarsk Region. The content of 137Cs in livestock products produced in farm biogeocenoses with additional technogenic load is higher than the average for the region, but does not exceed the criterion of regulatory documents; accordingly, radiation-safe agricultural products are produced on the territory of the Krasnoyarsk Region. For agricultural landscapes with absorbed doses of 1.33 and 1.55 mGy/year, a KP for the link “feed – livestock products” has been established. When the radioecological situation changes, the established Kp values can be used to predict the migration of 137Cs in the chain “soil – feed – livestock products”. A direct linear moderate Spearman rank correlation was identified between the specific activity of 137Cs in feed and the concentration of 137Cs in cow's milk. Linear regression equations have been determined to determine the specific activity of cow's milk based on data on the specific activity of 137Cs in feed. The revealed direct linear relationship indicates that even a slight increase in the 137Cs activity of the diet leads to an equivalent increase in the specific activity of technogenic cesium in cow's milk.

One pot synthesis of novel C3N4/C nanosheet composites under environmental benign molten salts for peroxymonosulfate activation with enhanced efficiency and reusability

The application of g-C3N4 based carbon materials in peroxymonosulfate (PMS) activation has faced challenges due to the electrochemically inert nature of nitrogen without light irradiation. In this study, two types of crystalline C3N4/C nanosheet composite catalysts were synthesized from glucose and dicyandiamide (DCD) via molten salt-assisted pyrolysis, denoted as M-GD and M-GD2. Both the composite catalysts showed significant improvement in the degradation of acid orange 7 amid PMS activation, taking the advantages of high graphitic N content and defect degree. Specifically, M-GD2 with excessive dosage of DCD exhibited a record catalyst specific activity value (0.0925 L min−1 m−2) in comparison with conventional C3N4 based carbon catalysts. The study also examined the effects of catalyst and PMS concentrations, temperatures, initial pH, and impurity ions on catalytic activity, as well as the catalytic performance in actual sludge wastewater cases. Notably, the M-GD2 catalyst exhibited exceptional regeneration capacity after four consecutive tests, attributed to its unique 3D structure comprising g-C3N4 nanoparticles loaded on crystalline C3N4/C nanosheets. Mechanism analysis revealed that a non-radical mechanism predominantly drove the PMS activation reaction, primarily involving catalyst-mediated electron transfer and surface-bound radicals due to the formation of catalyst-PMS* complexes. This work presents a facile and economical method for preparing defect-rich crystalline C3N4/C nanosheet composite with high graphitic N content, highlighting its catalytic activity, reusability, and regeneration performance synchronously. These findings contribute to advancing the field of PMS activation and offer promising applications in water environment remediation.

The development of titanium dioxide nanotube-supported CdTe catalysts for photocatalytic enzymatic glucose fuel cell and response surface methodology optimization

Energy is one of the critical needs for human life and well-being. Alternative energy sources are essential due to the increase in energy demand with the rise in population the development of industrialization, and the damage caused by fossil fuels to the environment. Fuel cells, an alternative energy source, are a clean and environmentally friendly technology that converts chemical energy into electrical energy. In this study, titanium dioxide (TiO2) nanotube (TNT)-support CdTe catalysts were synthesized by the wet impregnation (WI) method. Glucose oxidase (GOD) and laccase (LAC) enzymes were modified by incubation on CdTe/TNT catalysts. These enzymatic and non-enzymatic catalysts were characterized by scanning electron microscope-energy dispersive X-ray (SEM-EDX) and mapping, X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscope (TEM) analyses. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) analyses were used to examine the activity, resistance, and stability of catalysts for enzymatic photocatalytic glucose electrooxidation. The 3 % CdTe(50-50)-TNT-GOD/GCE electrode exhibited the highest activity, resistance, and stability under UV illumination compared to other electrodes. The modification parameters of the electrodes, incubation time, amount of catalyst ink, and drying time were found to be 136.96 min, 8.94 µL, and 21.30 min with response surface method (RSM) analysis, respectively. The estimated specific activity value was obtained as 0.754 mA/cm2 under optimized conditions.

C-terminal Poly-histidine Tags Alter Escherichia coli Polyphosphate Kinase Activity and Susceptibility to Inhibition

In Escherichia coli, many environmental stressors trigger polyphosphate (polyP) synthesis by polyphosphate kinase (PPK1), including heat, nutrient restriction, toxic compounds, and osmotic imbalances. PPK1 is essential for virulence in many pathogens and has been the target of multiple screens for small molecule inhibitors that might serve as new anti-virulence drugs. However, the mechanisms by which PPK1 activity and polyP synthesis are regulated are poorly understood. Our previous attempts to uncover PPK1 regulatory elements resulted in the discovery of PPK1* mutants, which accumulate more polyP in vivo, but do not produce more in vitro. In attempting to further characterize these mutant enzymes, we discovered that the most commonly-used PPK1 purification method – Ni-affinity chromatography using a C-terminal poly-histidine tag – altered intrinsic aspects of the PPK1 enzyme, including specific activity, oligomeric state, and kinetic values. We developed an alternative purification strategy using a C-terminal C-tag which did not have these effects. Using this strategy, we were able to demonstrate major differences in the in vitro response of PPK1 to 5-aminosalicylic acid, a known PPK1 inhibitor, and observed several key differences between the wild-type and PPK1* enzymes, including changes in oligomeric distribution, increased enzymatic activity, and increased resistance to both product (ADP) and substrate (ATP) inhibition, that help to explain their in vivo effects. Importantly, our results indicate that the C-terminal poly-histidine tag is inappropriate for purification of PPK1, and that any in vitro studies or inhibitor screens performed with such tags need to be reconsidered in that light.

Calculate the Rate of Natural Radioactivity in the Soil of Some Schools Using the NaI(Tl) Detector in the City of Hilla-Iraq

Activities and risk markers in 15-20 cm soil samples from Hilla City schools were thoroughly examined. This was made possible by the NaI(Tl) detector. The results indicated that the specific activity values for 238U from 2.244±0.06 Bqkg-1 to 23.637±0.60 Bqkg-1, with an average value of 11.70±0.39 Bqkg-1. Similar to 232Th, the average specific activity level was 8.53±0.31 Bqkg-1, ranging between 1.603±0.09 Bqkg-1 and 21.503±0.56 Bqkg-1. For 40K, its specific activity range was 222.96±2.72 to 441.824±2.78 Bqkg-1, with an average of 375.32±2.71 Bqkg-1. The average radiative forcing of the radium equivalent (Raeq) was calculated to be 52.80 Bqkg-1. The external risk index (Hex) was 0.14, and the internal risk index (Hin) was 0.17. The gamma risk index (Iγ) was determined to be 0.41. Also, the average outdoor absorbed dose level Dout is 26.35 nGyh-1, while the average indoor absorbed dose level Din is 50.54 nGyh-1. The average annual values of effective dose equivalents (internal and external) are 0.03 and 0.25 nGyh-1. The additional lifetime cancer risk ELCR(t) due to natural radioactivity in the models was 0.93x10-3. Note that the global average permissible nuclide concentration was 30, 32, and 420, and the danger index values were 1, 1, 6, 59, 84, 0.4, 0.07, and 1.45, respectively, based on the report of the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). After carefully comparing the study results with permissible global averages, they fit well within the recommended range.

Assessment of Radioactivity of Some Samples of Healthy Drinking Water and Liquefied Water in Some Areas of the Capital Baghdad Using HPGE Detector System

In this work, a total of 20 water samples were collected from various locations inside the city of Baghdad. Each sample consists of a volume of 1 litre of water which had been obtained from multiple geographical locations. There were twelve water samples representing pure tap water sourced from various locations additionally, eight samples of mineral water were obtained from several marketplaces in Baghdad. A total of six radionuclides were detected in the water samples using the HPGe detector. These radionuclides were identified as Bi 214, Ra 226, TI 208, Bi 212, Pb 212, and K 40. Among these, Bi 214 and Ra 226 are part of the U-238 series, while TI 208, Bi 212, and Pb 212 belong to the Th 232 series. Additionally, K 40 is a naturally occurring radionuclide. The observed minimum value for the average specific activity of radionuclides in pure tap water samples was Al-Yarmouk Pure tap water. However, the sample Hay Al-qahira pure tap water exhibited the highest recorded specific activity values of radionuclides in pure tap water. The observed minimum value for the average specific activity of radionuclides in mineral water samples was Bardaa mineral water. However, the sample (W15) exhibited the highest recorded values for the specific activity of radionuclides in mineral water. The measured external dosage of natural radioactivity in water samples from Baghdad was found to be relatively low, at 0.366 mSv.y-1. This value falls below the recommended limit the United Nations Scientific Committee set on the Effects of Atomic Radiation (UNSCEAR), 1 mSv.y-1.

Produksi Enzim Spesifik Xilanase pada Variasi Suhu Konsorsium Trikultur Bakteri Termofilik

Xylanase is an extracellular enzyme that is capable of hydrolyzing xylan (hemicellulose) into xylose and xylo-oligosaccharides. Xylanase can be produced by microbes through a fermentation process, the microbes used are thermophilic bacteria. Thermophilic bacteria are microorganisms that are capable of producing thermostable enzymes through fermentation. The bacteria used are MSS11, MS 16 and MS 18. These thermophilic bacteria can live at temperatures above 45°C-80°C. To determine specific enzyme activity, enzyme and protein activity values were tested using a 540 nm (enzyme) and 750 nm (protein) septovotometer. The method used in this research is descriptive in triplicate. The research was carried out at the Microbiology Laboratory, Faculty of Mathematics and Natural Sciences, Padang State University on December 23 2023. Beechwood medium which had been mixed with MSS 11, MS 16, and MS 18 bacteria was then incubated at temperatures of 55℃, 65℃ and 75℃ so that specific enzyme activity was obtained. Of these three temperatures, the optimum specific enzyme activity of xylanase is 65℃, where the specific enzyme value obtained at 65℃ is 3.31 U/mg. Meanwhile, at low temperatures, namely at 55℃, the enzymatic reaction is slow, namely it has an enzyme activity value of 1.02 U/mg. Finally, at a temperature of 75, there was a decrease in specific enzyme activity, where the specific enzyme activity value was 3.12 U/mg.

Assessment of the radiation risk to health caused by the intake of Cs-137 and Sr-90 radionuclides from food in the able-bodied population of the Samara region

Monitoring of the content of technogenic radionuclides (Cs-137 and Sr-90) in foods is one of the key areas in ensuring radiation safety of the population, taking into account the current radiation situation. The greatest risk to health is food produced or imported from the territories that have been subjected to man-made radiation accidents. The purpose of the research was to assess the radiation risk caused by oral intake of radionuclides based on the study of the actual nutrition of the adult population and contamination of food with Cs-137 and Sr-90 radionuclides. Material and methods. The specific activity of Cs-137 and Sr-90 radionuclides (median and 90 percentile) was assessed by gamma spectrometric method in 1235 samples of food produced in the Samara region and imported from outside. Data on the actual nutrition of 894 respondents aged 18 to 68 years (in the autumn-winter period) were obtained by the 24-hour dietary recall using the automated software package Nutri-prof (version 2.9). Based on the data obtained, effective annual doses of internal radiation were calculated, information was obtained on the risks of malignant neoplasms, including in the long-term period under various scenarios of internal radiation. Results. Radiometric studies of food samples did not reveal deviations from hygienic standards. The highest median values of Cs-137 specific activity were observed in samples of forest mushrooms (1.23 Bq/kg), wild berries (0.97 Bq/kg), fish and fish products (0.96 Bq/kg). The highest median values of Sr-90 specific activity were also observed in samples of forest mushrooms (3.86 Bq/kg), fish and fish products (2.71 Bq/kg). The radiation risk under various scenarios of Cs-137 intake was regarded as «negligible», while the risk was regarded as «small» when consuming food contaminated with Sr-90. The number of additional cases of malignant neoplasms at the admission of Cs-137 in the median values of specific activity is 0.38 per year, at maximum values - 0.57 per year, at the admission of Sr-90 - 2.04 per year and 3.30 cases per year, respectively. Conclusion. The implementation of radiation monitoring of food, especially those imported from areas of high radiation risk, is a necessary condition for ensuring radiation safety of the population. It is also necessary to take into account the stochastic effect of the influence of small doses of internal exposure on the organism when consuming food, which make a significant contribution to the formation of the dose of internal radiation.

Galvanic replacement synthesis of PtPdAu hollow nanorods as peroxidase mimic with high specific activity for colorimetric detection.

Noble metal nanomaterials have been widely demonstrated to possess intrinsic enzyme-like properties and have been increasingly applied in the fields of analysis and biomedicine. However, current exploration of high-activity noble metal nanozymes is still far from adequate. The construction of hollow structures and adjustment of their elemental composition are effective ways to improve the specific activity (SA) of nanozymes. In this study, trimetallic PtPdAu hollow nanorods (HNRs) were developed using a galvanic replacement reaction and Kirkendall effect. The catalytic experiment showed that the PtPdAu HNRs possessed outstanding peroxidase-like performance and their SA value was up to 563.71 U mg-1, which is remarkable among various previously reported nanozymes and higher than that of monometallic or bimetallic counterparts with similar structure and size prepared in this study. Electron paramagnetic resonance (EPR)measurements showed that the PtPdAu HNRs could contribute to the formation of hydroxyl radicals (˙OH) in catalyzing hydrogen peroxide. When using PtPdAu HNRs as a nanozyme in the colorimetric detection of H2O2 and ascorbic acid (AA), the limits of detection were as low as 1.8 μM and 0.068 μM, respectively. This study demonstrates that PtPdAu HNRs are high-activity nanozymes and have the potential to be applied in the field of analysis.

Spatial distribution of 137Cs; 40K, 226Ra, 232Th in soils of Monchegorsk city (Murmansk region)

The purpose of the study was to establish the patterns of spatial distribution of radioactivity of technogenic 137Cs and natural radionuclides 232Th, 226Ra, 40K in urban soils of Monchegorsk. Location and time of the study. Soil samples, were collected in summer 2018 in the Monchegorsk city, Murmansk region, Russia. To study the specific activity of radiocesium and natural radionuclides, soil samples were taken from topsoil (0-5 cm) at 82 sites, including 68 sites within the city territory (urban soils) and 14 sites beyond the city limits in the subtorch areas strongly affected by the Severonickel factory. Similar studies of urban soils in Monchegorsk had not been carried out previously. Methods. During expeditionary work and laboratory research, soil, radiological, and mathematical and statistical methods were used. When carrying out gamma spectrometric measurements, radionuclides 137Cs, 226Ra, 232Th and 40K were determined on a low-background semiconductor gamma spectrometer ORTEC (USA) based on a high-purity coaxial germanium detector GEM10P4–70 (HPGe) with a SBS-75 pulse signal processor and Gamma-software. The resolution of the gamma spectrometer along the 1.33 MeV line (60Co) was 1.75 keV, and the relative efficiency was 15%. Calibration and quality control of gamma spectrometric measurements was carried out using volumetric activity measurements with 1-L Marinelli vessels of different densities (RITVERZ, Russia-Germany). Main results. The values of specific activity of radionuclides in soil samples were as following: in the technogenic 137Cs up to 31.3 Bq/kg and in the subtorch soils up to 63.4 Bq/kg. Specific activity of natural radionuclides in urban soils reached to 14.2 Bq/kg for 226Ra, whereas in the subtorch soils it reached 21.6 Bq/kg. The specific activity of 232Th in urban soils reached 18.3 Bq/kg, with 17 Bq/kg registered for the subtorch soils. As for 40K, its specific activity reached 498 Bq/kg in the urban soils and 317 Bq/kg. Conclusion. The gamma survey of the Monchegorsk territory did not reveal any anomaly in radiation. The dose rate of gamma radiation in the city does not exceed 0.074 μSv/hour, which is less than the values elsewhere in Russia, ranging from 0.04 to 0.20 μSv/hour. The obtained data about specific activity of technogenic 137Cs and natural radionuclides 232Th, 226Ra, 40K in the Monchegorsk soils are typical for the Murmansk region.

Studying the possibility of applying spectral methods for the analysis of chemical elements and radionuclides

This article presents the results of a study of the possibility of using spectral methods for analyzing chemical elements and radionuclides. As is known, in uranium production processes, chemical elements and radionuclides behave differently and they are distributed in different concentrations. Therefore, the main tasks of analytics are to determine the concentration and specific activity values of chemical elements and radionuclides in samples taken from various uranium products of uranium production. The magnitude of radiation factors at a local location of a uranium product is assessed by determining the values of these factors and the amount of various radionuclides contained in these samples. In laboratory conditions, the concentrations of U were determined by X-ray fluorescence analysis, the specific activity of 230Th, 226Ra, 40K and 137Cs was determined by gamma spectrometric analysis, and the isotope concentrations of 234U, 235U, 238U were determined by alpha spectrometric analysis. The results obtained were compared with the passport data of standard samples - SOUR, OSK-6, OSK-9, OSGI. Determining the concentration and specific activity values of various chemical elements and radionuclides in uranium products is of scientific and practical interest, and solving this issue is an urgent task of nuclear physics and analytics.

Ecological and agronomic geoinformation system of
 radioactively contaminated lands of Tula Research Institute

Agronomic GIS has been developed in the ArcGis 10.5 in order to introduce a system of adaptive landscape farming on the radioactively contaminated territory of the Tulskii NII. 3D models were built in the ArcScene 10.5 on the basis of electronic maps for the best visualization the data. The project was created using information of soil characteristics, distribution of specific activity values for artificial 137Cs radionuclide in agricultural lands; characteristics of agricultural lands. AgroGIS contains electronic maps of the location of agricultural areas; structures of crop rotations; standard productivity; agrochemical cultivation of soils; relief; bias and exposition; agrochemical indexes of soils; surface activity values of 137Cs on agricultural land; risks of obtaining contaminated products.
 The electronic maps contain all the necessary information for planning agricultural production. It based on the characteristics of agrolandscapes, soils and relief. Users can edit and enter data in this project.

Response surface methodology optimization of electrode modification parameters toward hydrazine electrooxidation on Pd/MWCNT/GCE

In this study, MWCNT supported Pd (Pd/MWCNT) was synthesized by NaBH4 reduction method as catalyst for hydrazine electrooxidation reaction (HEOR). Characterization methods namely inductively coupled plasma mass spectrometry (ICP-MS), elemental mapping, and scanning electron microscopy with energy dispersive X-ray (SEM-EDX) were used to analyze the surface morphology and metal composition of the catalysts. The Pd/MWCNT catalyst's average particle size is estimated to be 6.35 nm based on SEM images. Glassy carbon electrode (GCE) modification parameters namely the amount of catalyst ink transferred to the GCE surface (Vs), ultrasonication time of the catalyst ink (tu), and the drying time of the Pd/MWCNT/GCE (td) were optimized by using response surface methodology as 4.92 μL, 1 min and 19.52 min, respectively. Experimental specific activity value for HEOR was obtained as 7.13 mA cm-2 with 2.59% deviation under optimum conditions. Optimization of electrode preparation conditions is an inexpensive and facile method that could be used to improve the performance of anode catalysts for fuel cells.

Isolation and purification of isocitrate lyase by chromatographic meth-ods from the liver of rats under conditions of alloxan-induced diabetes

The homogeneous preparation with isocitrate lyase activity was obtained from the peroxisomal fraction of rat hepatocytes using chromatographic methods. Male white inbred laboratory Wistar rats (Rattus norvegicus) were used as the object of the study. Experimental diabetes was induced by a single injection of a 5% alloxan solution. The development of diabetes was monitored by measuring blood glucose levels using a glucometer (SatellitePlus PKG-02.4). Blood sampling was carried out in the morning from the tail vein. On the 10th day of the experiment, laboratory animals were subjected to decapitation, previously euthanized with ether anaesthesia, to obtain liver tissue samples. For the isolation of a homogeneous preparation of isocitrate lyase (ICL, EC 4.1.3.1.), chromatographic methods were used. Purification included several stages: fractionation of the homogenate with ammonium sulphate, gel filtration on columns filled with Sephadex G-25 and ion exchange chromatography, which was the determining stage. The anion exchanger DEAE-Sephacel was used as a sorbent. This allowed to achieve a degree of purification of 12.12 for the first ICL isoform and 24.24 for the second ICL isoform. The specific activity for the first sample was 0.04 U/mg protein, and the yield was 26.3%. The specific activity value for the second form of ICL was 0.08 U/mg protein, and the yield was 47.4%. For elution from a column filled with DEAE-Sephacel was performed using step KCl gradient (60 mM – 200 mM). Identification of the resulting preparations was carried out spectrophotometrically, following the increase in the optical density, according to the Kornberg method (λ-324 nm). The presence of isoforms was determined by specific staining of the gel after PAGE electrophoresis. As a result of four-step purification, two isoforms with different from ICL (EC 4.1.3.1) from other sources electrophoretic mobility were obtained.

The Immobilization and Stabilization of Trypsin from the Porcine Pancreas on Chitosan and Its Catalytic Performance in Protein Hydrolysis

In this study, trypsin from the porcine pancreas was immobilized on a heterofunctional support prepared by activating chitosan (Chit) hydrogel with glutaraldehyde (GA), then functionalizing it with glycine (Chit–GA–Gly). The catalytic performance of the immobilized trypsin in the hydrolysis reactions was compared with the catalytic performance of the immobilized enzyme on glutaraldehyde-activated chitosan (Chit–GA) and chitosan hydrogel (Chit). The maximum concentration of immobilized protein on Chit–GA–Gly was approximately 16 mg·g−1 at pH 9.0 (5 mmol·L−1 buffer sodium carbonate) at 25 °C from an offered protein loading of 20 mg·g−1. This biocatalyst exhibited maximum specific activity (SA) of 33.1 ± 0.2 nmol·min−1·mg−1 for benzoyl-DL-arginine-p-nitroanilide (BAPNA) hydrolysis, twice as high as the enzyme immobilized on the classic Chit–GA support (SA values ranging between 6.7 ± 0.1 nmol·min−1·mg−1 and 8.1 ± 0.1 nmol·min−1·mg−1). The Elovich kinetic model was used to describe the adsorption process using low (3 mg·g−1) and high (20 mg·g−1) initial protein loadings. The optimum temperature for BAPNA hydrolysis catalyzed by the immobilized trypsin (60 °C) was 10 °C higher than that of its soluble form. Additionally, the immobilized enzyme was 16 to 20 times more stable than its soluble form at 50–55 °C. Thermodynamic studies were conducted to elucidate the kinetics of the thermal inactivation process of soluble and immobilized forms. Complete hydrolysis of bovine serum albumin (BSA) at 37 °C was achieved after 2 h using a soluble enzyme, while for its immobilized form, the hydrolysis yield was 47%. Reuse tests revealed that this biocatalyst retained 37% of its original activity after 10 successive hydrolysis batches. Based on these results, this support could be used as an interesting alternative for producing heterogeneous biocatalysts with high catalytic activity and thermal stability when producing protein hydrolysates.