Potassium Bichromate Research Articles

Eliminating the «memory effect» during mass spectrometric determination of mercury

When estimating mercury content by inductively coupled plasma mass spectrometry (ICP-MS), this element adsorbs on the surface of the sample introduction system of the instrument, which creates problems in the determination of trace amounts of mercury. Various methods of cleaning the instrument have been proposed in the literature. Objective: to experimentally compare the effectiveness of trace mercury removal methods proposed in the literature for elemental analysis by ICP-MS and to select the optimal cleaning agent. Methods: Mercury content in solution was determined by the Agilent Technologies 7900 inductively coupled plasma mass spectrometer using 202Hg isotope. Diluted solutions of nitric and hydrochloric acids, solutions of gold chloride, potassium dichromate, thiourea, L-cysteine, potassium bromide, potassium bromate of different concentrations in water and 1% nitric and hydrochloric acids, aqueous solution of ammonium pyrrolidinedithiocarbomate were used as washing agents. Results: The background level of mercury content is achieved by using solutions of copper chloride (5%), thiourea (0.01, 0.1, and 0.5%), L-cysteine (2%), potassium bromide and bromate (0.0005 M) in 1.0% hydrochloric acid solution. The background is lowered by using 3 and 5% HCl, potassium dichromate (60 mg/liter), potassium bromide and bromate (0.01 and 0.05 M) solutions in 1% hydrochloric acid. Application of aqueous solution of ammonium pyrrolidinedithiocarbamate causes sharp degradation of plastic tubes of the sample introduction system. Conclusion: The efficiency of washing agents based on hydrochloric acid is higher than that based on nitric acid and water. The most promising washing agents are bromide-containing solutions and potassium bichromate solution in hydrochloric acid. The optimal way to clean the device is its washing with 0.5 mM potassium bromide solution in 1.0% hydrochloric acid. Its use allows to reduce the background content of mercury and does not complicate the analysis of the content of other elements.

Mechanism of Cu-Pb selective flotation separation based on quercetin as a novel depressant

This study presents an organic reagent, quercetin, as a flotation depressant used to effectively separate chalcopyrite and galena. Quercetin and O-isopropyl-N-ethyl thionocarbamate (IPETC) are used as depressants and collectors, respectively, and results of micro-flotation tests showed that quercetin can depress galena and has less effect on chalcopyrite. Tests of artificially mixed samples of the chalcopyrite and galena show that the separation effect of quercetin as a depressant is better than that of sodium sulfate and sodium silicate combined depressant, it is close to that of potassium bichromate as a depressant, that is, it has the potential to be a depressant to achieve selective separation of chalcopyrite and galena. The X-ray Photoelectron Spectroscopy and Fourier Transform Infrared Spectroscopy results demonstrate that quercetin can chemisorb with oxidized metal sites on minerals’ surfaces. Results of the contact angle, adsorption capacity, and Atomic Force Microscope show that quercetin has comparable adsorption amounts on both minerals’ surfaces, and can hinder the IPETC adsorption on the mineral surface, but the amount of IPETC adsorb on chalcopyrite is much higher than on galena surfaces. The differences in the adsorption of the collector on their surface are the main reason for realizing the separation of chalcopyrite from galena.

CHANGES IN THE PIGMENT COMPOSITION OF RHODOPSEUDOMONAS YAVOROVII IMV B-7620 UNDER THE INFLUENCE OF HEAVY METAL SALTS

The aim of the study was to clarify the changes in the pigment composition of Rhodopseudomonas yavorovii IMB B-7620 under the influence of ferric(III) citrate, cobalt(II) chloride, copper(II) chloride and potassium bichromate. Materials and methods. R. yavorovii IMV B-7620 bacteria were grown at + 27 ... + 30 °C for 14 days in ATCC No 1449 medium supplemented with 1.0–12.0 mM ferric(ІІІ) citrate, 1–15 mM cobalt(II) chloride, 0.050–0.500 mM copper(II) chloride, or 0.010–0.045 mM potassium dichromate. The bacterial cells were sedimented, resuspended in acetone, and disintegrated by sonication. The resulting suspension was kept for 24 hours at -20 °C, after which it was centrifuged, and 0.5 ml of supernatant were filtered through membrane filters (pore diameter 0.45 μm). Chromatographic separation of pigments was performed using a high-performance liquid chromatography system. Results. On the 14th day of cultivation under the influence of heavy metal compounds, the qualitative and quantitative changes in the pigment composition in R. yavorovii IMV B-7620 cells occurred. Under the influence of ferric(ІІІ) citrate, cobalt(II) chloride, and potassium dichromate, a decrease in the pigment content in R. yavorovii IMV B-7620 cells was detected. The content of lycopene decreased by 22.1–83.9%, bacteriochlorophyll a – by 33.8–86.0%, compared to the control. Under the influence of copper(II) chloride, not only the pigment content but also the quantity of its isomers increased. Under the influence of the studied metal compounds, a small amount of anhydrorhodovibrin was detected in the cells, whereas it was not detected in the control. Conclusions. Under the influence of heavy metal compounds, changes in the qualitative and quantitative composition of pigments occur in the cells of bacteria R. yavorovii IMV B-7620. Ferric(III) citrate, cobalt(II) chloride and potassium bichromate caused a decrease in the pigment content in R. yavorovii IMV B-7620 cells. Under the influence of copper(II) chloride, not only the content of pigments increased, but also the quantity of their homologues and isomers, in particular lycopene, which can perform a protective function. Under the influence of all the studied metal salts, a small content of anhydrorhodovibrin was detected in the cells, which was not detected in the control. It can also contribute to the protection of cells from stressors.

Use of ceramic fiber modified with ferrites for the cleaning of flue gases of graphitization furnaces

Gaseous emissions of industrial enterprises as a result of their economic activities adversely affect the ecological situation, and even worsen the sanitary and hygienic working conditions of the personnel. Carrying out chemical reactions in the furnace equipment of metallurgical and electrothermal production, as a rule, lead to the formation of gases containing various toxic impurities, including carbon monoxide, the disposal of which is an important environmental task. As the calculations show, the total amount of annual CO emissions in Ukraine is 704344.218 t/year, which in percentage terms is 31.42% of the total emissions of pollutants and greenhouse gases, except for carbon dioxide - 2242020.75 t/year. The release of significant amounts of poisonous CO into the atmosphere is a serious problem that must be solved at the level of industrial production. One of the effective directions in the field of purification of industrial gas emissions from toxic carbon monoxide is the application of catalytic technologies due to the use of compositions based on transition metals, especially ferrite materials. Recently, systems for neutralizing toxic gases, including glass fiber catalysts, have become widely popular. The study of the CO oxidation process was carried out on a flow-type installation with a stationary weight of the catalyst. Catalytic purification of the gas mixture from CO was studied in the range of 50-450 °C. The concentration of carbon monoxide in the initial gas mixture at the entrance to the reactor was varied in the range of 1-2 vol. %. If necessary, helium was used as an inert gas. Ceramic fiber was used as a fiberglass support for catalytic systems for the oxidation of gaseous emissions containing CO. Ferrite catalysts were applied to ceramic fiber by the method of impregnation from sulfate solutions of iron, copper, and potassium bichromate. From the temperature dependences of the conversion of carbon monoxide with a concentration of 1-2% on ferrite catalysts on a ceramic fiber carrier, it can be seen that 100% conversion of carbon monoxide is not achieved even at a temperature of 450 ºС. In the case of using a mixture of magnetite and copper ferrite, the degree of conversion of CO was 97% at temperatures above 300 ºС and stably ensured the neutralization of CO until the conversion degree of 98% was reached at a temperature of 450 ºС. At a temperature of 450 ºС, the highest degree of conversion of 99% was ensured by using chromium ferrite, but the specified chromium-ferrite catalyst at a temperature of 400 ºС provided a slightly lower oxidation efficiency, that is, the specified catalyst has less advantages for use in fluctuating gas temperatures in industrial conditions. When magnetite and copper ferrite were used separately, the degree of CO conversion was 40% and 75%, respectively. Therefore, the conducted studies showed that the use of ceramic fiber modified with ferrites can be effectively used for the purification of flue gases of electrode graphitization furnaces, in particular, the neutralization of toxic carbon monoxide. Obtaining ceramic fiber modified with ferrite material does not require significant capital investments, as it is based on the use of liquid waste from etching, copper plating, and chrome plating of galvanic production. Laying ceramic fiber on top of the thermal insulation of the graphitization furnaces of electrode production will also reduce the inflow of oxygen into the porous space and reduce the formation of carbon monoxide, which will contribute to the improvement of the ecological situation at the electrode production. The obtained results on the use of ceramic fiber modified with ferrite material as a catalyst for the neutralization of carbon monoxide are a highly effective and affordable measure to reduce the man-made burden of electrode production on the environment.

Modifikasi Metode Kalium Bikromat Untuk Uji Kualitatif Alkohol Dalam Urine

Alcohol is a psychoactive substance that can cause dependence. Alcohol as an intoxicant can affect various structures and processes in the central nervous system and increase the risk of intentional and unintentional injury. One of the direct risks due to alcohol consumption is an accident while driving a vehicle and accidents at work. Rate alcohol It is measured in various body fluids including urine. This study aims to determine the sensitivity of the modified potassium dichromate method for qualitative test of alcohol in urine without filter paper and water bath. This research is a laboratory experimental study, the data obtained were analyzed in a descriptive way, namely seeing the color change of the reaction between the alcohol sample in urine and the Potassium bichromate reagent to green or blue with a modified working method. Tested all showed positive results with the modified Potassium bichromate method. A color change from green to blue is read as a positive alcohol result. The conclusion of this study is that the modified Potassium bichromate method is effective for the qualitative alcohol test process and there is an increase in the sensitivity of the test.

Effect of Boric Acid on Oxidative Damage in Immunocompetent Organs under Conditions of Potassium Bichromate and Gamma Radiation Exposure

The immune system supports antigenic homeostasis in the body and regulates the processes of proliferation and differentiation of cellular components in hemo- and immunopoiesis. Chromium compounds and ionizing radiation lead to the formation of highly reactive free radicals. Sublethal dose of gamma-irradiation is characterized by a 56% decrease in thymus cellularity and a 22% decrease in lymph nodes against the background of a 44% increase in the number of lymphoid cells in the spleen. Under the combined effect of hexavalent chromium and gamma-radiation, a decrease in the number of lymphoid cells is observed. In thymus the cellularity decreases by 70%, in spleen - by 40%, in lymph nodes - by 42% in comparison with control data. Under the influence of boric acid the number of lymphoid cells in thymus significantly increases by 47%, in lymph nodes - by 14% (p<0.05) compared to the data of irradiated animals. Boric acid administration weakens the development of oxidative stress, lipid peroxidation decreases, and the activity of antioxidant defense enzymes in immunocompetent cells is increased.

UJI KUALITATIF ALKOHOL URINE PEMINUM TUAK DALAM MENGETAHUI WAKTU SAMPLING YANG TEPAT

In making a diagnosis of the influence of alcohol on urine for a crime and the occurrence of traffic accidents, it is necessary to take the right sampling time. The influencing factor in determining the results of toxicological analysis is the time of sampling. In addition, another factor to consider when detecting alcohol in urine is the time of last consumption. This study was conducted to determine the appropriate urine sampling time for alcohol consumption. The method used in this urine alcohol qualitative test uses the modified 2.5% potassium bichromate method in 50% H2SO4. The sample consisted of 10 respondents who drank palm wine after 1 hour, 2 hours and 3 hours of consumption. The qualitative test results of urine drinkers of palm wine drinkers after 1 hour, 2 hours and 3 hours of consuming. 10 respondents obtained the results of 4 positive urine samples 1 hour after consuming and 2 positive urine samples 3 hours after consuming palm wine, as well as sampling in the 2nd hour the test results were negative. The positive test results depended on the habit of consuming, the volume consumed, and the age of the wine drinker.

Neomycin: sources of contact and sensitization evaluation in 1162 patients treated at a tertiary service

BackgroundNeomycin is used in several over-the-counter pharmaceutical formulations in Brazil. In Europe and Canada, where it is not freely available, its sensitization frequency is lower than in the United States, where this does not occur. ObjectiveTo present the frequency of sensitization to neomycin observed in a tertiary hospital and the pharmaceutical formulations sold in Brazil containing neomycin. MethodRetrospective analysis of positive results to neomycin, obtained through patch tests performed in a tertiary hospital, from 2009 to 2018 and investigation of topical drugs and vaccines containing neomycin in Brazilian databases available on the internet. ResultsAmong 1,162 patients, 71 (6%) had positive reactions to neomycin, 65% female and 35% male individuals, 46% were over 50 years old, and 24% had a personal history of atopy. The dermatitis lasted from four months to 20 years. Lesions were located in 69% of the patients on the upper limbs, in 55% they were on the lower limbs, and in 42% they were disseminated in more than 4 sites. Polysensitization was detected in 55% of cases. Of these, 28% were linked to sensitization to rubber allergens and 27% to potassium bichromate. A total of 158 topical presentations of neomycin were found: 79 ointments, 58 creams, 10 ophthalmic solutions, seven otological solutions, one oral solution, two nasal solutions, and one antiseptic powder, in addition to 11 types of vaccines. Study limitationsRetrospective study. ConclusionSensitization to neomycin occurred in 6% of the studied population, affecting more females aged over 50 years, with skin lesions located mainly on the upper and lower limbs, in the context of chronic contact dermatitis. Neomycin was found in 135 formulations, most of them available over the counter, as well as in 11 miscellaneous vaccines.

Features of phototropic response of zooplankton to paired photostimulation under adverse environmental conditions.

Our previous studies showed that the change in the plankton response to light could be an indicator of environmental pollution. This study experimentally reveals that the response of Daphnia magna Straus and Daphnia pulex plankton ensembles to photostimulation depends on the intensity of the attracting light. This makes it difficult to identify the occurrence and change of pollutant concentration. The large variability in the magnitude of the behavioral response is caused by the nonlinear response of plankton ensembles to the intensity of the attractor stimulus. As the intensity of the photostimulation increases, the variability of the phototropic response passes through increase, decrease, and relative stabilization phases. The paper proposes a modification of the photostimulation method-paired photostimulation involving successive exposure to two photostimuli of increasing intensity. The first stimulus stabilizes the behavioral response, while the increase in response to the second stimulus makes it possible to more accurately assess the responsiveness of the plankton ensemble. The paper studies the sensitivity of the method of paired stimulation of the behavioral response of different types of freshwater plankton ensembles: Daphnia magna Straus, Daphnia pulex to the effects of pollutants (potassium bichromate, microplastic). The study demonstrates good reliability and increased sensitivity of this method of detecting changes in environmental toxicity compared to single photostimulation or traditional bioindication through the survival rate of test organisms.

Determination the content of cysteine in food by potassium dichromate spectrophotometry

In this paper, a new method for the determination of cysteine by potassium dichromate spectrophotometry is established. In the H2SO4 medium, potassium dichromate has strong oxidation. Potassium dichromate can react with the hydrosulfuryl(-SH) in cysteine, which makes potassium dichromate fade, and the fading degree of potassium dichromate is proportional to the amount of cysteine added. Therefore, the content of cysteine can be quantitatively determined by determinating the decrease value of absorbance. The various influencing factors for the determination the content of cysteine by potassium bichromate spectrophotometry are investigated. Under the optimal conditions, the content of cysteine in food is determined, and the results are satisfactory.

INFLUENCE OF VITAMIN E ON THE HAEMODYNAMIC EFFECTS OF INTRAGASTRIC CHROMIUM INTAKE AND LIPID PEROXIDATION IN EXPERIMENTAL RATS

Purpose: To examine the possibility of using vitamin E for the correction of free radical oxidation disorders and haemodynamic effects of potassium bichromate. Methods: Experiments were performed in 90 male Wistar rats; the study included 9 experimental groups. Vitamin E and sunflower oil (control) were injected daily intragastrically through an atraumatic tube into the stomach. At the end of the experimental period (30 days and 60 days), the main parameters of systemic hemodynamics and values of lipid peroxidation were measured. Differences between groups were analyzed using Student’s t-test. Results: The analysis of basic parameters of systemic haemodynamics showed that PO administration of potassium bichromate promoted an increase in mean arterial pressure due to the increase in normalized peripheral vascular resistance (systemic vascular resistance, SVR). At the same time there was a decrease in the stroke volume index. The haemodynamic effects of chromium were more pronounced with prolonged administration. Parameters of systemic hemodynamics in combined administration of potassium bichromate and sunflower oil changed similarly to the effects of combined administration of the metal and vitamin E, but changes were less pronounced. A decrease in SVR and the restoration of the stroke volume index were observed. The isolated administration of the metal for thirty days resulted in an increase in lipid peroxidation (LPO) accompanied by a stimulation of catalase and superoxide dismutase activity. During prolonged (2 months) isolated administration of potassium bichromate, a more pronounced increase in LPO was observed along with the depletion of the antioxidant system. The prevention of chromium intoxication using vitamin E during the first month of administration reduced lipoperoxidation phenomena accompanying increased antioxidant defense activity. These dynamics persisted after two months of the combination of vitamin E and potassium bichromate. Conclusions: The intragastric administration of potassium bichromate for 30 and 60 days resulted in arterial hypertension in a rat model. The administration of toxic doses of potassium bichromate to laboratory animals may lead to the activation of lipid peroxidation. The administration of vitamin E may attenuate the haemodynamic effects of chromium intoxication and the activation of lipid peroxidation.

Micro-X-ray spectral determination of the chipboard dust samples elemental composition

The paper determines the composition of dust from electrostatic precipitators of EAF gas cleaners during long-term storage in dumps in order to obtain information on classifying dust as hazardous waste. Determination of the heavy metals content in waste was performed by atomic absorption flame spectrophotometry on an AAS-1N spectrophotometer. The content of the amount total iron and the determination of its various oxidation states was carried out by redox titration with potassium bichromate in an acidic medium. A comprehensive metallo-graphic study of dust samples included macroanalysis (at x16 magnification), microanalysis of the structure of the end section of pellets from fresh dust from EAF electrostatic precipitators using optical microscopy (x 50, x 500). A detailed analysis of the microstructure of the selected samples was carried out using a JSM-6490 scanning electron microscope in the mode of secondary elastically scattered electrons. The X-ray spectral analysis of the selected samples was carried out using energy and wave spectrometers attached to a JSM-6490 scanning electron microscope. Chemical analysis of dust samples showed that there are no significant differences in the content of total iron in the presented dust samples, although there is some decrease in the depth of the dump. A stronger decrease in the transition from the surface of the dump to the depth is noted by the content of Fe3O4. All samples are magnetic, which indicates a significant content of magnetic nitrous oxide-iron oxide in the dust, most likely in an unbound state. The presence of zinc and lead impurities in the melting charge, evaporating at the operating temperatures of the furnace, leads to their oxidation by the air flow, as a result of which they can be in the final dust both in the form of free oxides and in the form of composite structures with iron oxides. It has been established that the results of the chemical analysis of electrostatic precipitator dust samples, their qualitative composition and the content of toxic heavy metals, in general (according to the average value of 10 determinations) correspond to the given technical conditions of the enterprise for this type of waste, the excess was obtained in terms of the zinc content in all considered iron-containing wastes. A distinctive feature of heavy metals present in the waste is extremely low mobility in buffer media and practical insolubility in water.

The toxicity of Meistera chinensis rhizome fraction by shrimp larvae with the BSLT method

Meistera chinensis is a species that belong to the Zingiberacea family. In Southeast Sulawesi, a population of Meistera chinensis was found in the Abuki forest of Konawe Regency. Empirically, its consumed by the community as a cooking spice and body fitness. The results of previous research revealed that Meistera chinensis fruit is efficacious as an antioxidant, anticancer, antimicrobial and antifungal. Research on the rhizome has never been done. This study aims to determine the potential for toxicity and the LC50 value of Meistera chinensis rhizome using the BSLT method. The rhizomes were extracted with 96% ethanol and concentrated using a rotary evaporator. Then fractionation was carried out with methanol and ethyl acetate as solvents. The concentration of the rhizome fraction was 7.81 ppm, 15.63 ppm, 32.25 ppm, 62.5 ppm, 125 ppm, 250 ppm, 500 ppm and 1000 ppm. Positive control used of 1.4 mg potassium bichromate and negative control is DMSO. Toxicity was determined based on the mortality of shrimp larvae and calculated by determining the LC50 value. The results showed that the LC50 values ​​for the methanol, ethyl acetate and positive control fractions of Meistera chinensis rhizome were 252.88 mg/L, 57.17 mg/L, and 6.22 mg/L, respectively. Based on these results, it can be concluded that the Meistera chinensis rhizome fraction has a toxic effect on shrimp larvae (≤1,000 mg/L).

Экспериментальные и расчетно-аналитические исследования совместимости горючих веществ друг с другом и с окислителями

The danger of chemical reactions in the interaction of incompatible substances manifests itself in an increase in temperature and pressure, ignition, and finally, these reactions can be accompanied by an explosion. By the method of a constant volume bomb, the processes of interaction of mutually reacting substances are studied, as which mixtures of combustible substances (sodium, magnesium, sulfur, and an organic liquid — glycerin) with a changing mass of the oxidizer (ammonium nitrate, ammonium perchlorate, potassium permanganate, potassium bichromate) and in a mixture of these substances of stoichiometric composition are studied: a combustible component and an oxidizer. Analysis of the dependences of the coefficient of participation of a substance in an explosion on the coefficient of excess of an oxidizer of various interacting substances indicates that these dependences can be of two types: with an extremum and in the form of a direct dependence. Continuous increase in the coefficient of participation in the explosion with an increase in the coefficient of excess of the oxidizer indicates the ability to decompose and participate in the explosion of the oxidizer itself. This type of dependence established experimentally for the powders of combustible sulfur and magnesium with oxidizing agents-ammonium nitrate and ammonium perchlorate, shows that both combustible and decomposition products of a flammable oxidizing substance participate in the explosion. Other mixtures (magnesium, glycerin mixed with potassium permanganate, potassium bichromate) have an extremum, and the oxidizer does not participate in the pressure increase when the oxidizer content in the mixture increases. Calculation confirms the possibility of determining chemical compatibility (incompatibility) of substances using the standard Gibbs energy. Based on the example of the experimentally established incompatibility of mixtures of magnesium and sulfur with ammonium nitrate, the calculation also shows that these substances are incompatible with each other. In the absence of experimental data on the compatibility of substances, the input data for calculating the Gibbs energy, the information on the compatibility (incompatibility) of substances can be borrowed from tables 15–17 of GOST 12.1.004. Hazardous and especially hazardous substances indicated under numbers 3 and 4 in these tables are incompatible.

Phototropic response features for different systematic groups of mesoplankton under adverse environmental conditions.

Current trends in the application of bioindication methods are related to the use of submersible tools that perform real‐time measurements directly in the studied aquatic environment. The methods based on the registration of changes in the behavioral responses of zooplankton, in particular Crustaceans, which make up the vast majority of the biomass in water areas, seem quite promising. However, the multispecies composition of natural planktonic biocenoses poses the need to consider the potential difference in the sensitivity of organisms to pollutants.This paper describes laboratory studies of the phototropic response of plankton to attracting light. The studies were carried out on a model natural community that in equal amounts includes Daphnia magna, Daphnia pulex, and Cyclops vicinus, as well as on the monoculture groups of these species. The phototropic response was initiated by the attracting light with a wavelength of 532 nm close to the local maximum of the reflection spectrum of chlorella microalgae. Standard potassium bichromate was used as the model pollutant.The largest phototropic response value is registered in the assemblage. The concentration growth rate of crustaceans in the illuminated volume was 4.5 ± 0.3 ind (L min)−1. Of the studied species, the phototropic response was mostly expressed in Daphnia magna (3.7 ± 0.4 ind (L min)−1), while in Daphnia pulex, it was reduced to 2.4 ± 0.2 ind (L min)−1, and in Cyclops vicinus, it was very small—0.16 ± 0.02 ind (L min)−1. This is caused by peculiar trophic behavior of phyto‐ and zoophages. The addition of a pollutant, namely potassium bichromate, caused a decrease in the concentration rate of crustaceans in the attracting light zone, while a dose‐dependent change in phototropic responses was observed in a group of species and the Daphnia magna assemblage.The results of laboratory studies showed high potential of using the phototropic response of zooplankton to monitor the quality of its habitat thus ensuring the early diagnostics of water pollution. Besides, the paper shows the possibility of quantifying the phototropic response of zooplankton using submersible digital holographic cameras (DHC).

Clinical Pattern and Patch Test Profile of Hand Eczema in Hospital Employees in a Tertiary Care Hospital of North India.

Introduction:Health care workers form an important occupational group with a high risk of hand eczema. All health care professionals are exposed to a variety of allergens and irritants which can cause hand dermatitis, resulting in significant morbidity.Aims and Objectives:To assess the clinical profile of hand eczema in hospital employees, to perform patch test in relevant cases and to find out the most common sensitizers in them.Materials and Methods:This was a cross-sectional, hospital-based study in which the staff was screened for features of hand eczema and patch testing was done in the suspected cases of allergic contact dermatitis.Results:Out of 340 employees screened, 46 employees (13.5%) suffered from hand eczema. The most common type was wear and tear dermatitis accounting for 17 (36.9%) cases, followed by discoid eczema, pompholyx, focal palmar peeling, finger-tip eczema, hyperkeratotic eczema, ring eczema, and unspecified types. Patch testing was positive in 15 (32.6%) cases. The most common allergen was paraphenylene diamine, followed by fragrance mix, nitrofurazone, mercaptobenzothiazole, potassium bichromate, black rubber mix, and thiuram mix. A statistically significant association (0.001) was found with an underlying history of atopy.Conclusion:Hand eczema is a commonly encountered dermatological complaint in many hospital employees. Proper counseling, work, up, patch testing, and treatment can mitigate the symptoms in such employees.

Vickers microindentation deformation of different cleavage faces of potassium bichromate single crystals: Anisotropy in microhardness and crack formation

Experimental results of an investigation of anisotropy in microhardness measurements and crack formation on the {001}, {010} and {100} cleavage faces of potassium bichromate (KBC) single crystals by Vickers indentation deformation are presented and discussed. It was found that: (1) the experimental hardness HV data measured at indentation loads P up to 0.6 N reveal two or three regions of indentation diagonal d characterized by load-independent, normal or reverse indentation size effect (ISE), (2) in the range of measurement of the different d regions the ISE behavior is associated with the competition between factors related to the material deformation and the crack formation during indentation, (3) the value of intrinsic hardness Hin of KBC crystal, independent of applied load, indenter orientation and plane used for hardness measurement in the region of normal ISE, is 0.764 GPa, (4) the values of fracture toughness Kc depend on the crystallographic orientation of the investigated cleavage face as well as on the orientation of the indenter on it, and (5) the anisotropy in the arrangement of indentation cracks on the cleavage faces is a consequence of anisotropic distribution of indentation stress due to the triclinic structure of KBC crystals.

Aquatic ecosystem health assessment of a typical sub-basin of the Liao River based on entropy weights and a fuzzy comprehensive evaluation method

River ecosystem health assessments provide the foundation for river ecological protection and integrated management. To evaluate the aquatic ecosystem health of the Fan River basin, benthic macroinvertebrate indices (the Multimeric Macroinvertebrates Index Flanders (MMIF) and Family Biotic Index (FBI)), a habitat index (the river habitat quality Index (RHQI)) and a water quality index (the Improved Water Pollution Index (IWPI)) were selected. The entropy weighting method was used to calculate the RHQI and IWPI. A fuzzy comprehensive evaluation method was used to evaluate the aquatic ecosystem health. The evaluation results indicated that the aquatic ecosystem health of the Fan River basin was better in 2018 than in 2011, which respectively belonged to the ends of the 11th and 12th Five-Year Plans of the Major Science and Technology Programs for Water Pollution Control and Treatment in China. The proportions of sampling stations with good, moderate and poor grades in 2011 were 50.0%, 40.0% and 10.0%, respectively, and in 2018, the proportions of stations with excellent, good and moderate grades were 20.0%, 50.0% and 30.0%, respectively. A correlation analysis showed that the RHQI was significantly correlated with the MMIF, FBI and IWPI. The riparian land use pattern was an important factor that influenced changes in the aquatic ecosystem health grade. Of the water quality parameters, total phosphorous (TP) and potassium bichromate index (COD) were the main factors that affected the characteristics of benthic macroinvertebrates and the aquatic ecosystem health.

Effect of Sodium Tetraborate on Oxidative Damages in Heart Tissue in Chromium Intoxication

The cardioprotective effects of sodium tetraborate in chromium intoxication, correction of lipid profile and oxidative stress have been investigated. The experiment has been performed on 36 Wistar male rats, divided into 6 groups. I - control; II, III, and IV groups received potassium bichromate (K2Cr2O7) 700 mg/l with drinking water; rats of the III and IV groups received additionally orally a solution of sodium tetraborate (Na2B7O7) in doses of 22.5 mg/kg and 225 mg/kg per day, respectively. Animals of the V and VI groups received orally only Na2B7O7 solution at the rate respectively 22.5 and 225 mg/kg weight per day. The study duration was 21 days. The introduction of K2Cr2O7 increases content of malondialdehyde and carbonial protein in cardiac tissue, activates the antioxidant system of the heart, expands the levels of biomarkers of cardiotoxicity and increases the atherogenic index. The introduction of Na2B7O7 (22.5 mg/kg) reduces the toxic effect of K2Cr2O7 (cardioprotective effect). The use of Na2B4O7 (225 mg/kg) does not give a positive effect. In the group receiving only Na2B4O7 (22.5 mg/kg), inhibition of lipid oxidation and protein is observed, decrease of toxicity of biomarkers and low density lipoprotein-cholesterol (LDL-C), i.e. antioxidant effect. On the contrary Na2B4O7 (225 mg/kg) shows the prooxidant property.

Determination of Tiopronin using Potassium Bichromate Discoloring Spectrophotometry

A new method for the determination of tiopronin by potassium dichromate discoloring spectrophotometry is established. The optimal conditions for the discoloring spectrophotometric determination of tiopronin by potassium bichromate are discussed. In the sulfuric acid medium, potassium bichromate can oxidize tiopronin, and its absorbance decreases with the increase of tiopronin concentration. The decrease value of absorbance is linearly related to the concentration of tiopronin, and the content of tiopronin can be indirectly determinated by measuring the decrease value of absorbance. Within the scope of 0.02000-0.2000 mg/mL, the equation of linear regression is ΔA=-0.005+1.96C (mg/mL), and linear correlation coefficient is 0.9991. This method is used to the determination of tiopronin in tiopronin tablets, and the results consistent with standard method.