Residual Substances Research Articles

Boron doped diamond electrode in analytical chemistry: methods of electrode surface activation (а short review)

The review is presents to the feature of the use of a boron doped diamond electrode (BDDE) in analytical chemistry. BDDE –one of the most modern material, which is widely used in analytical chemistry and bioanalytical chemistry, as well as for organic synthesis, cleaning of the environment from pollution, medicine, etc. BDDE is becoming increasingly popular for voltammetric determination of residual amounts organic substances in complex objects (medicines, biological fluids, food). Nowadays use rod (disk) and film BDDE. The advantage of film electrodes is their portability and compactness, which, in turn, allows them to be used for rapid analysis of biological fluids, when one drop of sample is enough for analysis. BDDE require surface cleaning and activation, as do other stationary electrodes. In this paper, the main attention is focused on the features of BDDE activation surface for use in the analysis. Activate the electrode surface potentiostatically, galvanostatically and under dynamic conditions. Аlso use different background electrolytes. BDDE is usually electrochemically treated in aqueous solutions, mostly the surface of the electrode is cleaned and activated at the same time. Proper pre-electrochemical treatment can be a valuable way to achieve improved analytical properties of the methods of voltammetric determination. In this case, оbtain a more intense analytical signal, a narrower, clearer peak and/or a useful shift of the peak potential, which increases the sensitivity and selectivity of the determination. For the most part, activation in a medium of sulfuric acid with a sufficiently high concentration of 0.5–1.0 M is chosen as the optimal one. The electrode is polarized alternately anode and cathode (regardless of the chemical structure of the analyte or the nature of the electrode process). However, the method of activation must always be chosen experimentally. The review contains more than 80 references on the features of BDDE surface activation, including monographs, reviews, articles and original works. Keywords: voltammetry, boron doped diamond electrode, activation surface polarization.

Residual β-lactam antibiotics and ecotoxicity to Vibrio fischeri, Daphnia magna of pharmaceutical wastewater in the treatment process

The discharge of pharmaceutical wastewater introduces numerous pollutants into the environment, and their pollution level reduction has aroused extensive concern. This study investigated the variation in residual antibiotics and ecotoxicity to two nutritional-level model organisms in the pharmaceutical wastewater treatment process (PWTP). The wastewater in the equalization tank contained massive organic matters (2.9–18.7 times higher than the permissible values in GB21903-2008) and antibiotics (310.88 μg/L), posing extremely toxic effects to Vibrio fischeri (V. fischeri) and Daphnia magna (D. magna). The biological anaerobic/aerobic treatment units contributed the most to the reduction of antibiotics and the ecotoxicity to both organisms, with the removal rates of 72% and > 90%, respectively. The ecotoxicity of pharmaceutical wastewater was strongly and positively correlated with the residual antibiotics, amoxicillin, cephalexin, ammonia nitrogen, and total phosphorus (P < 0.05). However, the detected amounts of amoxicillin and cephalexin were approximately 105 times lower than the predicted no-effect concentrations of amoxicillin and cephalexin to V. fischeri and D. magna in freshwater, which implied the joint ecotoxicity posed by multicomponent mixtures, such as the residual antibiotics and organic toxic substances, rather than the specific residual antibiotics. This study provides a better understanding of the variations and residual levels of pollutants in PWTPs, including their ecotoxicity risk to the aquatic environment, highlighting the need to optimize pharmaceutical wastewater treatment technologies.

Thermogravimetric Experiment of Urea at Constant Temperatures.

There are still many unsolved mysteries in the thermal decomposition process of urea. This paper studied the thermal decomposition process of urea at constant temperatures by the thermal gravimetric–mass spectrometry analysis method. The results show that there are three obvious stages of mass loss during the thermal decomposition process of urea, which is closely related to the temperature. When the temperature was below 160 °C, urea decomposition almost did not occur, and molten urea evaporated slowly. When the temperature was between 180 and 200 °C, the content of biuret, one of the by-products in the thermal decomposition of urea, reached a maximum. When the temperature was higher than 200 °C, the first stage of mass loss was completed quickly, and urea and biuret rapidly broke down. When the temperature was about 240 °C, there were rarely urea and biuret in residual substance; however, the content of cyanuric acid was still rising. When the temperature was higher than 280°C, there was a second stage of mass loss. In the second stage of mass loss, when the temperature was higher than 330 °C, mass decreased rapidly, which was mainly due to the decomposition of cyanuric acid. When the temperature was higher than 380 °C, the third stage of mass loss occurred. However, when the temperature was higher than 400 °C, and after continuous heating was applied for a sufficiently long time, the residual mass was reduced to almost zero eventually.

Effect of water- and acid-pickling of aquaticplant biochar on the adsorption of Cd

To reveal the influencing factors and mechanism of adsorption of heavy metal Cd by biochar, different elution solvents (water and dilute acid solution) were used in this paper to elute the residual ash substances after pyrolysis of biochar, then the pH was regulated to investigate the adsorption effect of biochar on Cd in different treatment conditions. The precipitation experiments of Cd by biochar soaking and washing filtrate showed that the precipitation of root, stem and leaf of Acorus calamus L. contributed a great deal to the heavy metal removal system, which accounting for 81%, 77% and 98%, respectively, and the adsorption effect of biochar of roots, stems and leaves of Acorus calamus L. on Cd was slightly increased after washing. The adsorption experiment of biochar pickling on heavy metals showed that the adsorption effect of biochar on heavy metals Cd decreased greatly after pickling, which may be due to the removal of most of the minerals on the surface of biochar after pickling and the decrease of pH value of biochar. This work can provide insights into the use of biochar to control Cd.

Application of Augmented Reality Technology for Human Excretion System as Android-Based Learning Media

The excretion system is a process of removing metabolic waste that is no longer used by the body. These remnants of metabolism in the form of compounds that are toxic (poison) so that if not removed can cause disruption of the function of organs in the body. Organs that play a role in the excretion system are the kidneys, lungs, skin and liver. Kidney is the main component making up the human excretion system, namely urine. The lungs produce residual respiratory processes in the form of gas CO2 (carbon dioxide) and H2O (water vapor). The skin is able to produce residual substances in the form of sweat. The liver produces waste products in the form of bile sap from an overhaul of red blood cells that have been damaged and destroyed in the spleen. Augmented Reality Human Excretion System is an application that can facilitate teachers and class XI MA Tanwiriyyah students in learning about the human excretion system. This application is made based on Android by applying augmented reality technology in its implementation. In this application the teacher and students can see 3D objects and know the process of removing residual substances in the excretory system organs. The design of this application uses the MDLC method and also uses UML diagrams, navigation structures and application interface design.

Corpora Amylacea in the Human Brain Exhibit Neoepitopes of a Carbohydrate Nature.

Corpora amylacea (CA) in the human brain are polyglucosan bodies that accumulate residual substances originated from aging and both neurodegenerative and infectious processes. These structures, which act as waste containers, are released from the brain to the cerebrospinal fluid, reach the cervical lymph nodes via the meningeal lymphatic system and may be phagocytosed by macrophages. Recent studies indicate that CA present certain neoepitopes (NEs) that can be recognized by natural antibodies of the IgM class, and although evidence of different kinds suggests that these NEs may be formed by carbohydrate structures, their precise nature is unknown. Here, we adapted standard techniques to examine this question. We observed that the preadsorption of IgMs with specific carbohydrates has inhibitory effects on the interaction between IgMs and CA, and found that the digestion of CA proteins had no effect on this interaction. These findings point to the carbohydrate nature of the NEs located in CA. Moreover, the present study indicates that, in vitro, the binding between certain natural IgMs and certain epitopes may be disrupted by certain monosaccharides. We wonder, therefore, whether these inhibitions may also occur in vivo. Further studies should now be carried out to assess the possible in vivo effect of glycemia on the reactivity of natural IgMs and, by extension, on natural immunity.

DESIGNING TEXTILE WASTE SHREDDER MACHINE FOR CONTINOUS PRODUCT

The textile and textile products industry is one of the mainstay commodities of the manufacturing industry as well as a driving force for national economic development. Like any production process, the textile manufacturing process also produces waste or residual substances called textile waste. Likewise the impact of the activities of garment, tailor, fashion, apparel and convection, one of which is patchwork waste. If the patchwork waste is not handled properly, it will result in waste generation which will have an impact on pollution in the environment. Lack of tools that can treat textile waste, resulting in less optimal handling of textile waste. This research is trying to make a design of a cloth chopping machine that is used to crush the remains of large rags into small pieces of cloth. Thus the packaging of fabric waste is easier and more efficient, besides that it can also be used as raw material for other products so that it can reduce fabric waste that pollutes the environment. In developing the model and design of a textile waste chopping machine, this chopping machine will cut the patchwork which can be sized according to your wishes. It is hoped that the results of this research will contribute to the development, advancement and appropriate technology. The design of this textile fabric waste chopper will provide a practical solution and zero waste process in a textile and garment industry.

Synthesis of Uniform Gold Nanorods with Large Width to Realize Ultralow SERS Detection.

In this work, we successfully demonstrate high-yield synthesis of high-quality gold nanorods (Au NRs) with width ranging from 6.5 nm to 175 nm by introducing heptanol molecules as secondary templating agents during cetyltrimethylammonium bromide-templated, seeded growth method. The results show that an appropriate concentration of heptanol molecules not only alter the micellization behavior of CTAB in water, but also help silver ions impact the symmetry-breaking efficiency of additional Au-NP seeds in addition to enhancing the utilization of gold precursors. Moreover, the generality and versatility of the present strategy for synthesis of Au NRs with flexible controlled dimensions are further demonstrated by successful synthesis of Au NRs with the assistance of other fatty alcohols with properly long alkyl chains. Furthermore, when arrays of vertically aligned Au NRs with large width (AVA-Au120×90 NRs) are used as SERS substrates, they can achieve the ultralow limit of detection for crystal violet (10-16 M) with good reliability and reproducibility, and the rapid detection and identification of residual harmful substances.

Structural and Thermal Investigations of L-CuC4H4O6·3H2O and DL-CuC4H4O6·2H2O Single Crystals

Copper(II) L-tartrate trihydrate, L-CuC4H4O6&amp;middot;3H2O, and copper(II) DL-tartrate dihydrate, DL-CuC4H4O6&amp;middot;2H2O, crystals were grown at room temperature by the gel method using silica gels as the growth medium. Differential scanning calorimetry, thermogravimetric-differential thermal analysis, and X-ray diffraction measurements were performed on both crystals. The space group symmetries (monoclinic P21 and P21/c) and structural parameters of the crystals were determined at room temperature and at 114 K. Both structures consisted of slightly distorted CuO6 octahedra, C4H4O6 and H2O molecules, C4H4O6&amp;ndash;Cu&amp;ndash;C4H4O6 chains linked by Cu&amp;ndash;O bonds, and O&amp;ndash;H&amp;ndash;O hydrogen-bonding frameworks between adjacent molecules. Weight losses due to thermal decomposition of the crystals were found to occur in the temperature range of 300&amp;ndash;1250 K. We inferred that the weight losses were caused by the evaporation of bound water molecules and the evolution of H2CO, CO, and O2 gases from C4H4O6 molecules, and that the residual reddish-brown substance left in the vessels after decomposition was copper(I) oxide (Cu2O).

A novel silver(I) di-iso-butyldithiocarbamate: Unusually complicated 1-D polymeric structure, multiple ligand-supported Ag–Ag interactions and its capability to bind gold(III). Preparation, structural organisation and (13C, 15N) CP-MAS NMR of [Ag6(S2CNiBu2)6]n and [Au(S2CNiBu2)2][AgCl2

We have synthesised three new complexes of [Ag6{S2CN(iso-C4H9)2}6]n (1), [Au{S2CN(iso-C4H9)2}2][AgCl2] (2) and [Au{S2CN(iso-C4H9)2}2][Ag0.69Au0.31Cl2] (3), chemically identified these compounds using solution (1H, 13C) and solid-state (13C, 15N) CP-MAS NMR and FT-IR spectroscopy, and structurally characterised them by single-crystal X-ray diffraction analysis. There are six structurally inequivalent silver(I) centres in the former compound, whose unusually complicated, monodimensional polymeric structure is generally stabilised by six unequal iBuDtc ligands acting as bridges, along with numerous ligand-supported Ag–Ag interactions. Studying the capability of the precipitated AgiBuDtc to bind gold(III) from a [AuCl4]–/5.15 M NaCl solution, the double pseudo-polymeric heterometallic dithiocarbamato-chlorido complexes 2 and 3 were successfully obtained as individual fixation modes of gold to the solid phase. In the self-assembly of a bidimensional supramolecular structure of the latter two compounds, numerous interionic secondary bonds (Au···S, Ag···S and S···Cl), the anagostic HC···Ag interactions and the Cl···HC hydrogen bonds play a key role. To study the thermal behaviour of crystalline compounds 1 and 2, we additionally used simultaneous thermal analysis (STA). During the thermolysis of 1/2, the formation of Ag2S/AgCl,Au0 was supported, respectively, by energy dispersive X-ray (EDX) spectroscopy, while the dispersity and morphology of residual substances were studied using scanning electron microscopy.

Simultaneous determination of 11 prohibited and restricted veterinary drugs and their metabolites in animal-derived foods by ultra performance liquid chromatography-tandem mass spectrometry coupled with solid phase extraction

建立了固相萃取-超高效液相色谱-串联质谱(SPE-UPLC-MS/MS)同时检测鸡蛋、液态奶、鸡肉及淡水鱼中4类(氯霉素类、硝基咪唑类、林可酰胺类与大环内酯类)8种禁限兽药与3种代谢物残留的分析方法。对样品前处理及色谱条件进行优化,样品经0.1 mol/L pH 9.0的磷酸盐缓冲液水解分散,乙腈提取,提取液经乙酸乙酯萃取后浓缩至近干,残留物用0.3 mL甲醇溶解,再加入5.7 mL磷酸盐缓冲液,混匀,溶解液经Oasis HLB固相萃取柱净化后上机分析,以甲醇与0.1%甲酸水溶液作为流动相进行梯度洗脱,经ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)分离,采用ESI+和ESI-电离,在多反应监测模式下采集,同位素内标法定量。结果表明,11种待测物在色谱柱上完全基线分离,在各自范围内线性关系良好,相关系数(R2)>0.99,方法的检出限(LOD)为0.050~0.50 μg/kg,定量限(LOQ)为0.20~1.5 μg/kg。各待测物的平均回收率为65.3%~108%,相对标准偏差(RSD)为0.40%~21%。将该方法应用于市售样品中上述4类兽药残留的常规监测,其阳性样本的检测结果与标准方法测定结果无显著性差异。该方法灵敏度高,稳定性好,定量准确,适用于动物源性食品中多种禁限兽药及代谢物残留的同时快速测定。

Розроблення способу газифікації подрібненого вугілля

В основу роботи поставлено завдання створити спосіб газифікації твердого подрібненого палива, в якому внаслідок єдності процесу напівкоксування вугілля і газифікації напівкоксу, зв'язаного спільним контуром циркуляції твердого теплоносія, забезпечують простоту управління процесом і його стійкість, а знешкодження шкідливих речовин, які утворюються у процесі напівкоксування і газифікації палива, здійснюють допалюванням залишкових горючих речовин золи з надлишком повітря вище від стехіометричного значення. Поставлене завдання вирішують тим, що згідно з запропонованим способом газифікації твердого подрібненого палива, який полягає у попередньому підсушуванні та напівкоксуванні з подальшою газифікацією гарячого напівкоксу на паро-кисневому, або паро-повітряному дутті і очищенням генераторного газу від частинок коксу і золи, згідно з винаходом, здійснюють підсушування і напівкоксування палива у реакторі напівкоксування за рахунок тепла суміші гарячої золи і коксу, які виділяють з потоку генераторного газу під час його очищення, а гарячі гази і пари смол змішують з потоком гарячого генераторного газу для подальшої газифікації смол, напівкокс, який отримують після напівкоксування палива, газифікують у циркулюючому псевдозрідженому шарі, а частинки золи, після газифікації напівкоксу, подають на допалювання залишкових горючих і термічного знешкодження шкідливих речовин з надлишком повітря вище стехіометричного. Єдність процесу напівкоксування вугілля і газифікації напівкоксу, зв'язаного спільним контуром циркуляції твердого теплоносія, забезпечує простоту управління процесом і його стійкість. Потік золи, після газифікації напівкоксу, направляють на допалювання залишкових горючих речовин та вогневого знешкодження шкідливих речовин (фенолів, CaSO3, сірковуглецю та ін.). У процесі допалювання знешкоджують шкідливі хімічні сполуки, які утворилися на стадії напівкоксування і газифікації палива, захоплені зі золою (феноли, сірковуглець та ін.).

Ethanol Fermentation by High-Stress-Tolerance Aquatic Yeasts and Their Mutants

Bioethanol is thought to be a renewable source of energy, because the biomasses used to make ethanol, such as sugar cane and its residual substance, molasses, are resources that can be continuously produced. But the practical use of ethanol to replace fossil fuels or atomic energy has been limited, because the production efficiencies of ethanol in relation to its substrates are not so high. Thus, for industrial production of the bioethanol, yeast fermentation would ideally be carried out in biomasses containing more highly concentrated carbohydrates. However, the environmental stresses in highly concentrated cultures might weaken the yeast’s physiological activities. From various kinds of aquatic yeast with stress tolerance, Torulaspora derbrueckii F2-11 and Wicherhamomyces anomalus AN2-64 were selected as candidates for high-sugar-tolerance yeasts as they showed remarkable growth in the YPD + sorbitol (600 g/L) medium at 25°C for 120 hrs. When the amounts and kinds of sugar alcohols in the cells of the two strains were measured in cultures containing 20 g/L or 400 g/L of D-glucose, maltose, or sucrose, the main two sugar alcohols that accumulated as the sugar concentration increased were glycerol and arabitol. Mutation by ethyl methanesulfonate of the parent strains T. derbrueckii F2-11 and W. anomalus AN2-64 induced mutants F2-11M or AN2-64M, which showed higher sugar, heat, and ethanol tolerances than their respective parents. Ethanol productivities and sugar assimilation activities of the mutants were also higher than those of the parents in the 25% (v/v) molasses.

Determination of residual antibacterial substances in processed foods manufactured from livestock and marine products using HPLC

Determination of residual antibacterial substances in processed foods manufactured from livestock and marine products using HPLC

Experimental Study on Thermal and Catalytic Decomposition of a Dual-Mode Ionic Liquid Propellant

With the increasing of space activities and people’s awareness of environmental protection, it is necessary to develop a new non-toxic space propulsion system with high performance. Hydroxylammonium nitrate (HAN)/1-ethyl-3-methyl-imidazolium ethylsulfate([Emim][EtSO4]) blend ionic liquid propellant is a potential replacement with non-toxic and high-performance characteristics for hydrazine type liquid propellants, which can be used in both chemical and electrical propulsion system. This paper introduced the thermogravimetric experimental analysis (TGA-DSC) results of HAN/[Emim][EtSO4] ionic liquid propellant with the thermal decomposition and catalytic decomposition process. Its mass-loss process and exothermic process under different reaction conditions at a heating rate of 5K/min~15K/min were studied. Generally, the mass-loss results showed that there were four characteristic stages during the decomposition process of the HAN/[Emim][EtSO4] ionic liquids, which were the evaporation of the water solvent, decomposition of the HAN component, further decomposition of the [Emim][EtSO4], and slow loss of the residual substances. At the same time, two exothermic peaks were observed, which respectively corresponded to the decomposition of HAN and the further decomposition of [Emim][EtSO4]. Using catalyst can significantly reduce the decomposition temperature of the propellant and the residual mass. The contents in this paper proved that this propellant had a good application prospect within the catalytic ignition aerospace thruster.

Entrapment of drugs in dental calculus – Detection validation based on test results from post-mortem investigations

For prospective investigation of drugs and metabolites in archaeological and contemporary dental calculus, a sensitive, broadly applicable ultra-high-performance liquid chromatography-tandem mass spectrometry method using pneumatically assisted electrospray ionisation (UHPLC-ESI-MS/MS) was developed. The dental calculus was treated with citric acid and the dissolution extracts were cleaned using weak and strong polymeric cation-exchange sorbents. The method was validated on hydroxyapatite for the analysis of 67 drugs and metabolites. Typically, the lower limits of quantification were in the range of 0.01–0.05ng for the sample mass extracted. The general applicability of the method was tested using dental calculus material sampled from 10 corpses undergoing forensic autopsy. The calculus material was washed several times before dissolution to remove residual substances originating from saliva, gingival crevicular fluid and blood. The wash extracts and the calculus samples (cleaned calculus material) were analysed using the same instrumental conditions. The dry mass of the calculus samples ranged from 1 to 10mg. The total number of drug detections was 131 in the dental calculus samples and 117 in the whole blood samples. From the analyses of the wash extracts and calculus samples, it was proven that drug residues were trapped in the interior of the calculus material. In 82 of the drug detections, the drug concentrations were higher in the dental calculus than in the blood. Among substances detected in the dental calculus but not in the blood were cocaine, heroin, 6-MAM and THCA-A.

Influence of single post, oval, and multi-post restorative techniques and amount of residual tooth substance on fracture strength of endodontically treated maxillary premolars.

The aim of this study was to compare the influence of the number of coronal walls and post-endodontic restorations on the mechanical strength of 165 recently extracted endodontically treated maxillary premolars. The teeth were divided into 3 control (no post) and 3 test groups according to the number of residual walls. Each test group was divided into subgroups according to the type of post-endodontic restoration (single, oval, and multi-post techniques). Samples were prepared conforming to the assigned subgroup. A universal loading machine applied a load parallel to the longitudinal axis of the teeth, thus simulating physiological occlusion. ANOVA and the Kruskal Wallis test were used for comparisons (P ≤ 0.05), and Tukey's test for multiple comparisons. For intact teeth, significant differences were found among all 3 subgroups, with single post showing the highest values. For 3 residual walls, oval post resulted in significantly lower values than single and multi-post systems. For 2 residual walls, the multi-post technique showed almost twice the resistance of oval post restorations. In oval canals the use of a single or multi-post technique increased post-and-core resistance even in intact teeth, whereas oval fiber posts showed no improvements. Multi-post design improved fracture resistance mostly in maxillary premolars lacking both marginal ridges.

Experimental and Numerical Simulation Study of Devolatilization in a Self-Wiping Corotating Parallel Twin-Screw Extruder.

Devolatilization is an important process for separating and removing unnecessary residual volatile substances or solvents during the production of polymers using twin-screw extruders. Latinen proposed a surface renewal model to determine the concentration of volatile components in the extrudate of a single-screw extruder. When a twin-screw extruder is used to calculate the concentration, it is necessary to use the exposed surface area of the resin in the starved region of Latinen’s model, which, however, is difficult to estimate. In our previous work, we numerically determined resin profiles of the screws using the 2.5D Hele–Shaw flow model and the finite element method, which helps in estimating the surface area of devolatilization. In this study, we numerically analyzed the volatile concentration of the extrudate in a self-wiping corotating twin-screw extruder using Latinen’s surface renewal model along with our resin profile calculation method. The experimental results of the concentrations of the volatile component (toluene) in the extrudate of polypropylene agreed well with its numerical calculation with a relative error of 6.5% (except for the data of the lowest rotational speed). Our results also showed that decreasing the flow rate and increasing the pump capacity were effective for removing the volatile component. The screw pitch of a full-flight screw was not affected by the devolatilization efficiency with a fixed flow rate and screw speed.

Anti-Bacterial Properties of Bletilla striata Dihydrophenanthrene Against Extended Spectrum β-Lactamases-Carrying and Carbapenem-Resistant Escherichia coli from Hospital Clinical Practice

The present study was aimed at investigating anti-bacterial effects of Bletilla striata dihydrophenanthrene (DHP) on clinically isolated Escherichia coli (E. coli), including extended spectrum β-lactamases (ESBLs)-carrying E. coli and carbapenem-resistant E. coli (CRE). The minimum inhibitory concentrations (MIC) of two extracts, DHP and residual substances extracted by ethanol and n-butanol (NBE), were determined by the serial dilution method. The light absorption value of macromolecular substances, total leakage rate, and total protein content in the nutrient solution were determined by spectrophotometric analysis. Quantification of protein expression and drug susceptibility verification were determined by mass spectroscopy. In addition, the elimination of drug-resistant plasmids was evaluated. Our data showed that the DHP had a more powerful antibacterial effect on E. coli than that of NBE, with MICs of 0.82–1.38 mg/mL and 1.07–1.51 mg/mL, respectively. In addition, DHP enhanced the absorbance value of macromolecular substances, and increased protein expression in E. coli when compared with NBE. Moreover, NBE increased the total leakage rate of small molecule substances, total protein content, and reversed drug resistance when compared with DHP. Both NBE and DHP eliminated the banding patterns related to multidrugresistant plasmids, selectively inhibited bacterial growth and reversed multidrug resistance by regulating cell membrane permeability and protein expression levels in E. coli. The reversal of drug resistance may be mediated through elimination of drug-resistant plasmids in E. coli. Therefore, DHP and NBE may be promising antibacterial drug candidates, and DHP is more likely.

Идентификация антибиотиков в мясе. Возможности проточной цитометрии

The problem of the uncontrolled use of antibiotics currently remains unresolved. Step-by-step monitoring of meat using modern methods will reduce the risk of using contaminated meat raw materials for food production. Qualitative monitoring will identify samples containing residual antimicrobial substances. The use of methods for identifying groups of antibiotics will help narrow the search for antibiotics by expensive chromatographic methods. A study was carried out of beef, pork and poultry meat, which is used in meat processing plants in the production of raw smoked sausages, using two methods. At the first stage, using a qualitative microbiological method, the raw meat was evaluated for the presence of antimicrobial substances, then their group was determined using a NovoCyte flow cytometer. According to the results of a study on a flow cytometer, it was found that out of 10 groups of antibiotics that can be determined by the tested method, the group of lincosamides was not found in all meat samples. The most common groups of chemotherapy drugs in pork were sulfonamides – 29.6 %, tetracycline group – 18.5 % and beta-lactams – 14.8 %, and in beef aminoglycosides – 36.7 %, phenicols – 30 % and beta-lactams – 13.3 %. In poultry meat samples, the most common were sulfonamides – 23.2 %, fenicols – 23.2 %, and beta-lactams – 16 %. Five groups of antibiotics were found in all studied types of meat: fenicols, β-lactams, macrolides, polypeptide antibiotics, and quinolones. This indicates their widespread use in animal husbandry and poultry farming.