Iodide Solution Research Articles

Use of Magnetic Fields for Surface Modification of PbI2 Layers to Increase the Performance of Hybrid Perovskite Solar Cells

Hybrid perovskite films are prepared via two-step spin coating. The impact of magnetic fields during the spin coating of the PbI2 precursor solution is assessed with atomic force microscopy and scanning electron microscopy of the obtained layers. Deeper and narrower peak–valley–peak formations are obtained in PbI2 films when the magnetic field applied and the spinning direction result in a Lorentz force that pushes the [PbI6]4− ions towards the inner area of the substrate. This produces rougher and more porous PbI2 films with an increased surface area that facilitates the infiltration of the methylammonium iodide and chloride precursor solution, thereby enhancing the formation of perovskite. Increased cell performance and more repeatable results are obtained when the PbI2 film is spin-coated under the influence of a negative magnetic field. Opposite effects are obtained when the direction of the magnetic field, and therefore the Lorentz force, is inverted. This demonstrates that a magnetic field can be used to modify the surface morphology of spin-coated thin films prepared from ionic precursor solutions.

Influence of substrate temperature on the chemical, microstructural and optical properties of spray deposited CH3NH3PbI3 perovskite thin films

Methylammonium lead iodide (CH3NH3PbI3) perovskite has been proposed as a key component of thin film solar cells. In this work, the influence of substrate temperature on the properties of spray deposited CH3NH3PbI3 thin films was investigated. The main purpose of this work was to determine the best conditions to deposit and crystallize CH3NH3PbI3 perovskite thin films in a single step. An automatic spray system was used for depositing a solution of lead iodide and methylammonium iodide onto heated substrates under ambient conditions for just one second. After deposition the samples were held at the same temperature for 30 s. The substrate temperature varied from 60 °C to 140 °C. Substrate temperatures in the low range (60 °C–80 °C) led to films with needle-like or dendritic grains, extra phases, and poor coverage due to the low solvent evaporation rate, while depositions above 120 °C led to thermal decomposition of the film. The best results were obtained for substrate temperatures of 100 °C and 120 °C, which produced dense perovskite films with large equiaxed grains and good coverage. The transmittance spectra of these films showed the perovskite characteristic absorption edge at 780 nm. In addition, the Fourier-transform infrared spectra did not show any peaks associated with the solvent, confirming its evaporation and indicating that a 31 s overall processing time is enough to achieve a full perovskite crystallization.

Effect of carboxymethyl cellulose on the corrosion behavior of aluminum in H2SO4 solution and synergistic effect of potassium iodide

The corrosion inhibition of aluminum in 2 M H2SO4 solution by carboxymethyl cellulose (CMC) alone and in combination with iodide ions has been investigated using electrochemical measurements and surface analysis techniques. The results showed that CMC moderately inhibited aluminum corrosion in the H2SO4 solution, and the inhibition efficiency of CMC was increased with the addition of inhibitor concentration, indicating the physical adsorption mechanism. The synergistic effect of 5 mM KI at all concentrations of CMC was assessed by calculating the synergism parameters, indicating that the increased inhibition efficiency of the CMC caused by addition of iodide ions is due to synergism. Additionally, the analysis of the morphology and composition of the aluminum surface suggests that with addition of iodide ions, more CMC molecules are adsorbed on the aluminum surface, thereby enhancing the inhibition efficiency of CMC.

The apoptotic and free radical–scavenging abilities of the protein hydrolysate obtained from chicken feather meal

This study examined the antioxidant capabilities of peptides derived from chicken feather meal (CFM) protein hydrolysates which were produced using 3 different microbial proteases (Neutrase, Alcalase, and flavourzyme) and tested at varying concentrations, namely 1, 2, and 5% by weight. The highest levels of 2,2-diphenyl-1-picrylhydrazl (DPPH) and 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS) radical scavenging activities were presented by CFM hydrolysate derived using 5 wt% Neutrase and digested for 4 h. Fractionation of this particular hydrolysate was then performed by applying 10, 5, 3, and 0.65 kDa molecular weight cutoff membranes. It was then determined that the molecular weight (MW) < 0.65 kDa fraction achieved the greatest level of free radical scavenging activity in the context of DPPH and ABTS. The MW < 0.65 kDa fraction then underwent additional fractionation using reverse-phase high-performance liquid chromatography to derive 3 main fractions designated as F1, F2, and F3. All of these fractions presented a high level of activity in DPPH radical scavenging, although no significant ABTS scavenging was observed. Quadrupole time-of-flight tandem mass spectrometry was used in determining the peptide contents of the fractions as Phe-Asp-Asp-Arg-Gly-Arg-X for F1 (FDDRGRX, 875 Da), Val-Thr-Leu-Ala-Val-Thr-Lys-His for F2 (VTLAVTKH, 868 Da), and Val-Ser-Glu-Ile-X-Ser-Ile-Pro-Ile-Ser for F3 (VSEIXSIPIS, 1,055 Da). Moreover, the F2 fraction was shown to be capable of preventing DNA damage induced by hydroxyl radicals, as indicated in tests using the plasmids pKS, pUC19, and pBR322 via the Fenton reaction. This outcome was demonstrated through in vitro antiproliferative activity in human cell lines based on SW620 colon cancer, using the 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay. The F2 fraction at 0.5 wt.% was also shown to be capable of inducing weak early apoptosis, which could be measured by using the Fluorescein isothiocyanate Annexin V Apoptosis Detection Kit with Propidium Iodide Solution. Furthermore, an increase in caspase-3 and caspase-8 activity was observed in SW620 cells following exposure for 24 h and 48 h.

Understanding of chemical reactions induced by argon plasma in contact with sodium halide solutions: importance of surface properties for plasma–liquid interactions

Plasma in contact with liquid is widely studied in research involving water purification, nanoparticle synthesis, biomedical applications, and so on. However, plasma–liquid interactions, which are physical and chemical phenomena occurring at a plasma–liquid interface, have not yet been fully understood. To deepen our understanding of the interactions, in this study, we have investigated where specifically short-lived active species generated by plasma react with solutes at the plasma–liquid interface. We adopted chloride (Cl−), bromide (Br−) and iodide (I−) ions as indicators of the reaction region of the short-lived active species, because it is known that these halide ions are located closer to the gas–liquid interface in an order of I−, Br−, and Cl−. A DC argon plasma was irradiated to 2.1 mol l−1 sodium chloride (NaCl), bromide (NaBr), and iodide (NaI) solutions, and we found that chlorine was not detected after 600 s plasma irradiation while bromine and iodine were observed after 30 s plasma irradiation. To explain the different characteristics of halogen (chlorine, bromine, and iodine) generation, we postulated that, because of the surface activity and low kinetic energy of the short-lived active species generated by plasma, they could react with the solutes only at the topmost layer of the water surface, which is an atomic monolayer in liquid in contact with the gas phase. Based on our suggestion, we could say that the Cl− is unable to react with the active species into the chlorine because the ions were excluded from the topmost layer, and that, by contrast, the Br− and I− were able to react into the bromine and iodine, respectively, because some of these ions were located in the topmost layer. For understanding the plasma–liquid interactions more, a difference between chemical reactions induced by plasma and conventional electrolysis has been also discussed.

Subcutaneous phycomycosis involving the anterior abdominal wall in an immunocompetent boy successfully treated with potassium iodide

Subcutaneous phycomycosis is a chronic deep fungal infection caused by Basidiobolus ranarum, which usually occurs in children, predominantly affecting males. Herein, we report subcutaneous phycomycosis in a 3-year-old boy who presented with a gradually progressive painless swelling over the anterior abdomen of 20-day duration. Lesional biopsy confirmed the diagnosis of subcutaneous phycomycosis which revealed multiple well-defined granulomas composed of histiocytes, epithelioid cells, and multinucleate giant cells with broad nonseptate hyphae stained with Gomori methenamine silver stain. The child was managed with a saturated solution of potassium iodide which completely melted the swelling.

Effect of three silver diamine fluoride application protocols on the microtensile bond strength of resin-modified glass ionomer cement to carious dentin in primary teeth.

Use of silver diamine fluoride (SDF) after selective caries excavation can arrest the further progress of the carious lesion. Application of potassium iodide (KI) can reduce the staining due to SDF. The aim of the study was to evaluate the effect of the application of SDF, with and without acid etching and KI on the bond strength of resin-modified glass ionomer cement (RMGIC) to the carious dentin of primary teeth. In thisin vitro study, caries was induced on the occlusal surface by inoculating Streptococcus mutans strain in 36 extracted primary molars. The teeth were divided into four groups (n = 9), and the following treatments were done to the carious dentin prior to final restoration with RMGIC: Group I: 10% polyacrylic acid conditioner, Group II: 38% SDF, Group III: 37% phosphoric acid etchant followed by 38% SDF, and Group IV: 37% phosphoric acid etchant followed by 38% SDF and 10% potassium iodide solution. The microtensile bond strength was measured using universal testing machine. Failure modes were recorded using a scanning electron microscope. There was no significant difference in microtensile bond strengths between the groups (P = 0.665), with the highest value seen in Group III. Application of SDF with or without acid etching and KI does not affect the bond strength of RMGIC to carious dentin of primary teeth.

Solute transport in porous media studied by lattice Boltzmann simulations at pore scale and x-ray tomography experiments.

With the aid of nondestructive microfocus x-ray computed tomography (CT), we performed three-dimensional (3D) tracer dispersion experiments on randomly unconsolidated packed beds. Plumes of nonreactive sodium iodide solution were point injected into a sodium chloride solvent as a tracer for the evaluation of the dispersion process. The asymptotic dispersion coefficient was obtainable within the experimental scale and was summarized over Péclet numbers from 11.7 to ∼860. Then, the lattice Boltzmann method and moment propagation method were used to elucidate the mechanisms embedded in the dispersion phenomenon. The methods were rigorously verified against the classical Taylor dispersion problem and extended to simulate fluid flow and tracer dispersion in high-resolution 3D digital porous structures from CT. The method of moments, Lagrangian velocity correction function, and dilution index were thoroughly analyzed to evaluate the dispersion behaviors. Numerical simulations revealed ballistic and superdiffusive regimes at the transient times, whereas asymptotic dispersion behaviors appear at longer characteristic times. Besides, the observed transient times unanimously persist over convective length scales of around 12 particles transversely and 16 particles longitudinally. The estimated dispersion coefficients from simulation are in consistence with the experimental result. Furthermore, the simulation also enabled the identification of regimes, including diffusive, power law, and mechanical dispersion. Thus, the proposed experimental and computational schemes are of practical means to study dispersion behaviors by direct pore scale imaging and modeling.

Variación estacional de la densidad de granos de almidón en rizomas de Canna glauca y C. indica (Cannaceae)

Dado el conocido uso alimenticio de los rizomas de Canna glauca y C. indica, resulta interesante conocer si existen diferencias entre las dos especies en la acumulación de almidón en los rizomas y la posible variación estacional anual. Para su estudio se trabajó con material fresco recolectado en las cuatro estaciones del año. Mediante una observación macroscópica colorimétrica practicada sobre secciones transversales de los rizomas sobre las que se aplicó solución de ioduro de potasio iodado (lugol), se determinó la presencia de almidón en los rizomas. Este método permitió además estimar la abundancia por la intensidad de coloración. Para la determinación cuan- titativa se calculó la densidad de granos de almidón por mililitro de agua destilada en cámara de Neubauer, empleando una solución acuosa de parénquima del rizoma y lugol. Desde el punto de vista cualitativo y cuantitativo, en ambas especies la acumulación de almidón alcanzó su máximo en el período otoño-invernal y comparando las dos especies, la abundancia de almidón en este período del año fue mayor en C. indica, lo cual la indica como la más promisoria para ensayar su cultivo para alimento y producción de almidón en el área rioplatense.

Impact of Chlorine Doping on the Performance of Perovskite Solar Cells

In this paper the effect of Cl doping on optical, photovoltaic and morphological properties of mixed halide perovskite (CH3NH3PbI3-xClx) structure in a solar cell has been reported. The perovskite layer was spin-coated by employing sequential deposition method over a PEDOT-PSS hole transport layer. Lastly, the device was finished by coating Al via thermal evaporation. The addition of 10% methylammonium chloride (MACl) by weight into the methylammonium iodide (MAI) solution as additive was improved the photovoltaic performance of the solar cell, since the Cl doping has positive effect on the growth of perovskite crystals in the final film. Furthermore, addition of MACl enables the formation of smoother films and thus reduces photocurrent leakage due to pinholes or incomplete surface coverage. The Cl doping also increases reproducibility of planar devices for consistent device results.

Effects of anti-solvent in the two-step fabrication of absorber layer in perovskite solar cells

Hybrid organic-inorganic perovskite materials, e.g., CH3NH3PbI3 (MAPbI3) have been used as photon absorber layer in the emerging solar cell technology. The two-step spin coating technique has been employed to fabricate the absorber films. It has been found that the use of anti-solvents plays a crucial role on the growth of the perovskite crystals. Chlorobenzene (CB) and Toluene (TO) were chosen as the anti-solvents that were applied after spin-coating of Methylammonium Iodide (MAI) solution in the second step of the two-step process. The amount and the elapsed time of the application of anti-solvents after spinning MAI solution were varied and studied for the crystal growth of perovskite films as well as the performance of the perovskite solar cells (PSCs). It was found that 50 ml of CB applied at 5 s after spinning MAI solution yielded the best solar cells parameters with the best efficiency of 16.8 %.

IONOMETRIC DETERMINATION OF ZINC IN MILK

The possibility of ionometric determination of zinc in the rhodanide complex form in milk is represented. The indicator electrode was ion-selective electrode (ISE) with solution of tetradecylammonium bromide in nitrobenzene as a membrane. As a complexing agent the potassium thiocyanate with 1.0 mol/l optimal concentration in investigated solutions was selected. The calibration dependence E = f(pCZn(II)) were typical anionic functions. The steepness of the electrode function (29±2 mV/pC), close to the theoretical value for the doubly−charged ions, suggests that the electrochemically active anions are [Zn(NCS)4]2-. The interval of linearity of calibration curves is 1.0 to 5.7 pC, the detection limit is equal to 1∙10-6 mol/l. The selectivity of determination of zinc in the rhodanide complex form was investigated with “The mixed solutions” method in the presence of potassium, calcium, aluminum, iron (III), manganese (II), copper (II) chlorides potassium iodide and nitric acid solutions. The background concentration of extraneous (j) substances in investigated solutions was calculated with usage of published data and corresponds to their maximum content in milk. It was founded that the ionometric determination of zinc is possible in range from 1.0 to 5.0 pC for all investigated j-ions. The technique for different types of milk was developed including preliminary sample preparation, used in special certified laboratories and based on dry mineralization of sample and dissolving in nitric acid solution. The concentrations of zinc-ions in analyzed samples were determined with “limiting solutions” method. The correctness of obtained data was confirmed with “entered-found” scheme. The relative standard deviation was not higher then 0.08.

Improving the power conversion efficiency of perovskite solar cells by adding carbon quantum dots

High-quality perovskite films are the key factor in manufacturing high-performance devices. In this work, we for the first time use carbon quantum dots (CQDs) as additive in the methylammonium iodide solution for high-quality CH3NH3PbI3 (MAPbI3) films. Appropriate concentration of CQDs (0.04 mg ml−1) can passivate the crystal defects, improve the crystallinity, increase the grain size and reduce the grain boundary of MAPbI3 film. Various characterization results show that CQDs additive can reduce trap-state density, decrease carrier recombination and improve photoelectric performance. Compared with the pristine device, the average power conversion efficiency (PCE) of CQD-modified MAPbI3 device was increased from 15.8 ± 0.37% to 18.81 ± 0.45%, and the maximum PCE of champion device was increased from 16.21 to 19.17%. In this study, we propose a simple method for the preparation of stable and efficient inverted planar structure perovskite solar cells using CQD additives in a two-step spin-coated deposition method.

Methanesulfonyl Iodide

Methanesulfonyl iodide is produced in aqueous solutions from the reaction of triiodide with methanesulfinate. Dichroic crystals of (CH3SO2I)4·KI3·2I2 are formed from KI/I2 solutions with high concentrations of CH3SO2-, while dichroic crystals of (CH3SO2I)2·RbI3 are formed from RbI/I2 solutions. X-ray crystallography of these two compounds shows that the CH3SO2I molecules coordinate through their oxygen atoms to the metal cations and that the S-I bond length is 2.44 Å. At low concentrations of CH3SO2-, the solutions remain homogeneous and the sulfonyl iodide is formed in a rapid equilibrium: CH3SO2- + I3- ⇌ CH3SO2I + 2I-, KMSI = 1.07 ± 0.01 M at 25 °C (μ = 0.1 M, NaClO4). The sulfonyl iodide solutions display an absorbance maximum at 309 nm with a molar absorptivity of 667 M-1 cm-1. Stopped-flow studies reveal that the equilibrium is established within the dead time of the instrument (∼2 ms). Solutions of CH3SO2I decompose slowly to form the sulfonate: CH3SO2I + H2O → CH3SO3- + I- + 2H+, khyd. In dilute phosphate buffer, this decomposition occurs with khyd = 2.0 × 10-4 s-1; the decomposition rate shows an inverse-squared dependence on [I-] because of the KMSI equilibrium.

Normal saline solution is as effective as povidone iodine in preoperative vaginal cleansing before short duration gynecological laparoscopy

Laparoscopy is a minimally invasive method used for diagnostic and therapeutic purposes. Our objective was to compare the postoperative vaginal irritation symptoms and infection rates after using povidone-iodine (PI) and normal saline (NS) solution in vaginal cleansing before short duration gynecological laparoscopy. Randomized, single-blind clinical trial. All eligible participants who scheduled for short duration gynecologic laparoscopic procedures included diagnostic laparoscopy, bilateral ovarian drilling, and tubal sterilization were invited to participate in the study. Eligible participants were randomly allocated in a 1:1 ratio to two groups. Group I "PI group" where they subjected to PI for vaginal cleansing before laparoscopy and group II "NS group” where they subjected to the standard saline solution for vaginal cleansing. Two sponges of the same size and type were used for cleansing by both preparations. The primary outcome of the study was the difference in the rate of self-reported postoperative vaginal irritation symptoms after using PI and NS for vaginal cleansing. The secondary outcomes included the rate of postoperative fever ≥38 °C during the first 24 hours, persistent vaginal irritation symptoms, urinary tract infection, candidal vaginitis and bacterial vaginosis and endometritis at one-week post-procedure. The outcome variables were calculated using an unpaired t-test and chi-square test. Two-hundred forty-four women were analyzed in both groups (121 women in the arm). Both groups were similar regarding the mean age, residency, woman's education, parity, BMI and operative time. Diagnostic laparoscopy was the most common laparoscopic procedure performed during the study period (84.29%), tubal sterilization (7.85%) then bilateral ovarian drilling (7.43%). The mean overall vaginal irritation symptoms in PI group were significantly more than that observed in the NS group (p=0.0001). The overall infection rates in the PI group were 15.9%, while in the NS group was 10.16 % without a statistically significant difference in both groups (p=0.567). Both groups were quite similar in the rate of postoperative fever (p=0.505), urinary tract infection (p=0.654), vaginal candidiasis (p=0.254), bacterial vaginosis (p=0.366) and postoperative endometritis (p=0.749). Being less irritant, normal saline can substitute iodide solution as a vaginal cleansing tool before short duration gynecologic laparoscopy without increasing the risk of postoperative infection.

Lead Sulfide Quantum Dot Photodetector with Enhanced Responsivity through a Two-Step Ligand-Exchange Method

Recently, lead sulfide (PbS) quantum dots (QDs) have demonstrated great potential in becoming one of the most promising next-generation photoelectrical materials for photodetectors. PbS QDs provide fascinating properties including size-controllable spectral sensitivity, a wide and tunable absorption range, cost-efficient solution processability, and flexible substrate compatibility. One of the key problems that limit the performance of PbS QDs-based photodetectors is inefficient carrier transfer. Long ligands decorating the outside surface of PbS QDs to protect them against degeneration inhibit the transfer of electrical charge carriers and thereby limit the device performance. To overcome this problem, the long ligands need to be effectively exchanged. Here, a two-step ligand-exchange method is demonstrated. The QDs are pretreated using methylammonium iodide in solution as the first step ligand exchange before the layer-by-layer deposition process and solid-state ligand exchange. The grazing-incidence small-angle X-ray scattering and X-ray photoelectron spectroscopy analyses prove a smaller spacing among the QDs and an increased ligand-exchange ratio by adopting the two-step method. This strongly indicates a better capability of charge transfer than the traditional one-step solid-state ligand-exchange technology. Devices fabricated using the two-step method present an enhancement of the charge-transfer capability with a larger current. The efficient charge transfer is further demonstrated by a significant 94% increase of the responsivity and a 57% enhancement of the detectivity of the PbS QDs-based photodetector, reaching 3302 mA/W and 5.06 × 1012 J, respectively.

Pediatric Sporotrichosis in Jilin Province of China (2010-2016): a Retrospective Study of 704 Cases.

Pediatric patients make a substantial contribution to the epidemiologic profile of sporotrichosis in Jilin Province, a region of China in which the disease is strongly endemic. However, the exact epidemiologic and clinical manifestations of childhood sporotrichosis in China are unclear. The medical records of 704 pediatric patients aged <15 years with sporotrichosis diagnosed by fungus culture at the Department of Dermatology at the First Hospital of Jilin University in a 7-year period (January 2010 to December 2016) were reviewed retrospectively. The patients were from rural areas of Jilin Province, located in northeast China. Among the 704 pediatric patients, the male/female ratio was 1.41:1, and the highest incidence of sporotrichosis (63%) occurred in those aged 0 to 6 years; 561 patients (80%) contracted sporotrichosis in a colder month. Overall, 655 (93%) patients had lesions in the facial region, whereas 602 (86%) patients had fixed cutaneous sporotrichosis. The incidence of the fixed cutaneous form in the 0- to 6-year age group was significantly higher than that in the 7- to 14-year age group (P = .009). Patients were treated with 10% potassium iodide solution, itraconazole, or terbinafine. The characteristics of pediatric sporotrichosis in Jilin Provence include the following: (1) a more frequent occurrence in the colder months; (2) the facial region is affected predominantly, in most cases manifesting in the fixed cutaneous form; and (3) significantly more cases occur in younger children than in older ones. Decaying cornstalks used as fire materials might be the source of infection in this population; however, additional research is needed to explore the exact mechanism of infection.

Crystallization and grain growth regulation through Lewis acid-base adduct formation in hot cast perovskite-based solar cells

The precise control of perovskite crystallization process that could provide smooth films with large grains is a prerequisite for solar cell fabrication to achieve higher efficiencies. To regulate this crystallization process and to achieve it multiple times remains a humongous challenge. This process has been reproducibly demonstrated here through efficient molecular exchange via a Lewis acid-base adduct formation. In this work, a Lewis acid-base adduct approach in concurrence with hot casting technique was employed to efficiently control the perovskite crystallization by judiciously adding dimethyl sulfoxide (DMSO) to a precursor solution of lead iodide (PbI 2 ) and methyl ammonium chloride (MACl) in dimethylformamide (DMF). High quality perovskite films were fabricated by precisely controlling the volume of DMSO which resulted in low recombination rate and which had better light harvesting ability. Uniform films of MAPbCl x I 3-x having large grain size were formed reproducibly on addition of 1.5 equivalents (eq.) DMSO to the precursor solution. Perovskite solar cells fabricated using this solution resulted in maximum power conversion efficiency (PCE) of 14.11% with enhanced stability as compared to the reduced PCE values obtained with other DMSO ratios and pure DMF solution cast films. • Hot casting using Lewis acid-base approach resulted in large grain perovskite. • 1.5 equivalents of Lewis base (DMSO) gave largest grain size and smooth film. • A power conversion efficiency >14% achieved in inverted perovskite solar cell. • This method also improved the overall stability of the solar cells.

MoS2 Doping Using Potassium Iodide for Reliable Contacts and Efficient FET Operation

In this paper, we have demonstrated few-layer MoS2 doping using potassium iodide (KI) solution to realize stable/reliable ohmic contacts and achieve efficient electron transport. We have shown that KI doping allows MoS2 doping with a dopant density up to ${1}\times {10}^{{12}}\,\,\text {cm}^{-{2}}$ near source/drain edge. The same has been explained using density-functional-theory (DFT)-based band structure calculations. KI doping of MoS2 resulted in contact resistance reduction by $3.5\times $ ( $0.75\,\,\text {k} \Omega {-}\mu \text {m}$ ). The proposed technique and improved contacts have also resulted in $2\times $ improvement in ON-state current ( $500~\mu \text {A}/\mu \text {m}$ ), transconductance and field-effect mobility ( $70~\text {cm}^{{2}}/\text {Vs}$ ) without compromising with OFF-state behavior, while maintaining ON to OFF ratio well above $10^{{6}}$ . The reproducibility of the transistor characteristics after a longer period (2 months) confirms the stability of proposed doping technique against environmental conditions.

ЭКСПРЕСС-ОБНАРУЖЕНИЕ ХИМИЧЕСКИХ ВЕЩЕСТВ НА ПОВЕРХНОСТИ ОБОРУДОВАНИЯ ХИМИЧЕСКИ ОПАСНЫХ ОБЪЕКТОВ

Рассмотрены и оценены аналитические системы, пригодные для создания комплекта средств экспресс-обнаружения методом колориметрии загрязненности поверхностей оборудования химически опасных промышленных объектов гидразином (его производными), азотной кислотой и оксидами азота. В качестве элементов для индикаторных составов экспресс-обнаружения гидразина и его производных выбраны водные растворы хлорида, нитрата или сульфата кобальта(II), а для экспресс-обнаружения азотной кислоты и оксидов азота - подкисленные водные растворы иодида калия с добавкой крахмала. Предложено техническое решение реализации комплекта в форме аэрозольной упаковки многоразового использования. Основные преимущества комплекта - высокая чувствительность и специфичность к определяемым веществам, время обнаружения - не более 2 мин, сохранение индикационного эффекта - не менее 5 мин, простота в использовании (не требуется специальная подготовка) и др. Комплект рекомендуется применять для быстрой индикации загрязненности поверхности указанными токсикантами с целью определения наличия микротечей в деталях оборудования и остаточной загрязненности различных его поверхностей. Analytical systems suitable for creating a tool set for rapid colorimetric detection of surface contamination of the equipment of chemically hazardous production facilities with hydrazine (its derivatives), nitric acid, and nitrogen oxides, are considered and evaluated. An indication system for rapid detection of hydrazine and its derivatives is based on aqueous solutions of cobalt(II) chloride, nitrate or sulfate, while elements for indication system for rapid detection of nitric acid and nitrogen oxides are acidified aqueous solutions of potassium iodide with starch addition. A technical solution for implementation of express detection tool kit in the form of reusable aerosol packaging is proposed. The main advantages of the kit are high sensitivity and specificity for detectable substances, short detection time (not exceeding 2 minutes), duration of indication effect (at least 5 minutes), ease of use (no special qualification is required), etc. The tool kit can be applied for determining the presence of micro leakages in technical equipment parts and equipment surface residual contamination with the hazardous chemical compounds.