Instrumental Methods Research Articles

Direct ion chromatographic method for speciation micro analysis of arsenic forms in industrial samples with “rich” matrix composition

The speciation analysis of arsenic has consistently been a subject of great interest. However, it remains challenging to analyze complex matrix samples that contain both arsenic and interfering components. In this case, it can be hard to choose the right combinations of different instrumental methods, or a separation method followed by detection, which is usually done using a spectral approach (hybrid methods). In the production control of copper electrorefining, the determination of the concentration of As (III) and As (V) helps to improve the quality of the cathode copper produced. This work investigated the possibility of directly determining both arsenic forms and total As in an electrolyte bath using ion chromatography (IC) with conductometric detection. The use of the ion chromatographic approach for the determination of As(V) in complex matrix samples such as copper electrolyte must take into account the presence of potential interferences from anions such as sulphates, sulfites, selenites, selenates, etc. The results revealed that the method is accurate and precise, with As(V) quantification limits of 15 µg.L-1 and detection limits of 5 µg.L-1. This method is suitable for assessing various types of arsenic in the production of electrolytic copper, with the aim of replacing the current technique that requires liquid-liquid extraction and ICP-OES detection. This led to the following improvements: Enhanced efficiency: The method eliminates the need for extensive and time-consuming sample preparation for the initial separation of arsenic forms. At the same time, the method's characteristics are comparable to those of ICP-OES with liquid-liquid extraction, which is often used in the speciation analysis of arsenic. The method is environmentally friendly as it avoids the use of organic and poisonous extractants. The method can simultaneously analyze other anions (PO43-, SO42-, F-, Cl-, etc.) with arsenates with appropriate calibration.

АНАЛИЗ КАЧЕСТВА ПОЛИМЕРИЗАЦИИ БАЗИСНЫХ ПЛАСТМАСС

The issue of restoring dental defects is relevant for modern dentistry. Restoration of the functions of the dental system is possible by partial or complete removable laminar dentures which basis is made of lamellar plastics in the most cases. It is necessary to strictly observe the temperature regime of polymerization of plastics, since structural defects in the material can form, causing complications after prosthetics. There are devices for automatic polymerization with a temperature control function, but the most common is the classical method (in a water bath) of making denture bases. Purpose of the study: compare the quality of polymerization of base plastics using the classical method and using modern equipment. Materials and methods: 8 plastic samples were made, 50% of which were polymerized using the classical method, and the other half using an apparatus for hot polymerization of plastic. An external inspection of the samples was carried out and the finishing time of the plates was estimated. After polishing, the samples were examined using an electron microscope. Results and discussion: samples, polymerized using the classical method showed signs of granular porosity, the polishing time was 8 minutes 13 seconds; electron microscopy results revealed the presence of defects, which could lead to complications. Plates polymerized by the instrumental method are homogeneous, polishing time is on average 4 minutes 42 seconds. When these plates were examined with an electron microscope, there were minor defects. Conclusion: it is recommended to polymerize base plastics using devices for hot polymerization of plastics in order to prevent complications from using removable dentures.

Impact of the Extent of Population Aging on Economic Development and Countermeasure

With the comprehensive prosperity and development of human society, human life expectancy shows a rising trend, fertility rate shows a declining trend, the world is facing a severe problem of population aging, the ensuing economic impact is the focus we need to pay attention to. Taking various countries and regions in the world from 1960 to 2019 as samples, this paper conducted an empirical test on transnational panel data and found that old age dependency would significantly hinder economic growth. The conclusion remained valid after the robustness test of replacing explanatory variables, instrumental variable method and changing sample interval. Further study found that old-age dependency ratio will also significantly reduce consumption expenditure. Based on this, this paper gets inspiration and puts forward corresponding policy suggestions to mitigate the adverse impact of population aging on China's social and economic development.

Allergic rhinitis: a brief overview of the etiopathogenesis and rehabilitation of patients

The article presents a brief overview of modern literature sources concerning the prevalence, etiopathogenetic approaches in the diagnosis and treatment of allergic rhinitis. The relevance of the problem under consideration is due to the high prevalence of this pathology, the variety of etiopathogenetic mechanisms and the variability of classifications. One of the most popular classifications is seasonal. When studying pathogenetic mechanisms, the following patterns were revealed: the nasal mucosa is the main air conditioner of the respiratory tract and the first line of defense against infectious agents transmitted by airborne droplets. These roles require maintaining and restoring epithelial integrity and the ability to initiate immune responses. When conditions or factors are present that compromise the integrity of the mucosa, the epithelium releases alarmins and other molecular patterns associated with damage that trigger repair mechanisms but can also cause protective inflammation. In allergic rhinitis, the same mechanisms can activate the development of the disease. Many authors consider various diagnostic methods for allergic rhinitis. Such as a detailed and competent collection of complaints and anamnesis, including family history, physical examination, endoscopic examination of the nasal cavity, rhinomanometry, skin prick tests, radiological studies, including computed tomography of the paranasal sinuses, intradermal tests, study of total and specific immunoglobulins E in blood serum, basophil activation test, nasal provocation test, nasal cytology and biopsy histology, acoustic rhinometry, nasal inspiratory peak flow testing, and nitric oxide measurements are used. Attention is also paid to laboratory and instrumental methods for the differential diagnosis of rhinitis of pseudoallergic origin; the following methods are used: ultrasound diagnostics of the hepatobiliary system, biochemical blood test, and immunological studies. Treatment of patients with allergic rhinitis requires an integrated and interdisciplinary approach and, of course, requires differential and personalized methods taking into account etiopathogenetic mechanisms.

ИССЛЕДОВАНИЕ ВОЗНИКНОВЕНИЯ ПОЖАРА ОТ ВОСПЛАМЕНЕНИЯ И ВЗРЫВА ПАРОВОЗДУШНОЙ СМЕСИ ПРИ ПРОВЕДЕНИИ ГАЗОСВАРОЧНЫХ РАБОТ

Using the example of a real fire that occurred as a result of violations of fire safety requirements during gas welding operations, it is demonstrated how the combined use of instrumental and computational methods makes it possible to determine the cause of the fire. The nature of combustible substances has been determined by fluorescence spectroscopy, gas-liquid chromatography and infrared spectroscopy. Using mathematical calculations, the amount of combustible substances necessary for the formation of an explosive mixture was determined. It is demonstrated how a combination of physical-chemical research methods and computational methods, allows for the determining the causal relationship between gas welding operations and the aforementioned explosion.

Validation and quantification of peptide antigens presented on MHCs using SureQuant.

Vaccines and immunotherapies that target peptide-major histocompatibility complexes (peptide-MHCs) have the potential to address multiple unmet medical needs in cancer and infectious disease. Designing vaccines and immunotherapies to target peptide-MHCs requires accurate identification of target peptides in infected or cancerous cells or tissue, and may require absolute or relative quantification to identify abundant targets and measure changes in presentation under different treatment conditions. Internal standard parallel reaction monitoring (also known as 'SureQuant') can be used to validate and/or quantify MHC peptides previously identified by using untargeted methods such as data-dependent acquisition. SureQuant MHC has three main use cases: (i) conclusive confirmation of the identities of putative MHC peptides via comparison with an internal synthetic stable isotope labeled (SIL) peptide standard; (ii) accurate relative quantification by using pre-formed heavy isotope-labeled peptide-MHC complexes (hipMHCs) containing SIL peptides as internal controls for technical variation; and (iii) absolute quantification of each target peptide by using different amounts of hipMHCs loaded with synthetic peptides containing one, two or three SIL amino acids to provide an internal standard curve. Absolute quantification can help determine whether the abundance of a peptide-MHC is sufficient for certain therapeutic modalities. SureQuant MHC therefore provides unique advantages for immunologists seeking to confidently validate antigenic targets and understand the dynamics of the MHC repertoire. After synthetic standards are ordered (3-4 weeks), this protocol can be carried out in 3-4 days and is suitable for individuals with mass spectrometry experience who are comfortable with customizing instrument methods.

Dyeing behaviour of iron(III)-gallic acid complexes on wool as function of pH-dependent iron(III)-complex stoichiometry

Iron complexes with polyphenolics e.g. gallotannins and flavonoids have been used since ancient times for coloration of textiles, painting and preparation of inks. The composition of iron gall inks on historical artefacts has been investigated with modern instrumental methods. However the dyeing behaviour of iron-complexes with polyphenols still bases on empirical knowledge. In this study Fe(III)-complexes with gallic acid were used as model system to elucidate their pH dependent sorption and dyeing behaviour on wool. At dyebath pH 3 high sorption of Fe(III)-gallic acid complexes was observed, however darker dyeings were obtained at dyebath pH 4. Model calculations for the complex species present in the dyebath indicated the presence of the binary complex [Fe(III)(GA2−)]+ as main species at pH 3, while at pH 4 the ternary species [Fe(III)(GA2−)2]- prevails. The dye sorption bases on Van-der-Waals forces, while ionic interactions between Fe(III)-complex and keratin are of minor relevance. The elaborated theoretical model also explains the influence of dyebath pH in dyeing with gallotannins, polyphenols and flavonoids in presence of iron salts and thus is of particular relevance for improved utilisation of these natural colorants.

An Instrumented Sharp Indentation Method for Measuring Equibiaxial Residual Stress without Using Stress-Free Specimens

An Instrumented Sharp Indentation Method for Measuring Equibiaxial Residual Stress without Using Stress-Free Specimens

Pd-Co Supported on Anodized Aluminium for VOCs Abatement: Reaction Mechanism, Kinetics and Applicability as Monolithic Catalyst

It has been found out that Pd-Co-based catalyst, supported on anodized aluminum, possesses very high activity in combustion reactions of C1–C6 alkanes and toluene. The catalyst characterization has been made by N2-pysisorption, XRD, SEM, XPS, FTIR, TEM, and EPR methods. In view of the great interest, methane combustion was investigated in detail. It is ascertained that the complete oxidation of methane proceeds by dissociative adsorption on PdO and formation of hydroxyl and methyl groups, the former being highly reactive, and it undergoes further reaction to oxygen-containing intermediates, whereupon HCHO is one of them. The presence of Co2+ cations promotes greatly oxygen adsorption. The dissociative adsorption is favored on neighboring Co2+ cations, leading to the formation of bridging peroxides. Further, the oxygen dissociates on the nearest Pd2+ cations. According to the results from the experimental data, instrumental methods, and the observed kinetics and DFT model calculations, it can be concluded that the reaction pathway over Pd+Co/anodic alumina support (AAS) catalyst proceeds most probably through Mars–van Krevelen. The obtained data on the kinetics were used for simulation of the methane combustion in a full-scale adiabatic reactor.

Brody's abscess of the humerus is the cause of sepsis in a patient with coronavirus infection (COVID-19)

Purpose: To conduct a clinical and morphological analysis of the case of death as a result of sepsis, the cause of which was Brody's abscess.Material and methods. An analysis of the fatal outcome of a 54–year-old patient who occurred in a hospital of a medical organization where he received medical care for a disease – a new coronavirus infection. The complex of clinical, laboratory and instrumental diagnostic methods could not explain the progressive deterioration of the severity of the patient's condition and the onset of death.Results. During the autopsy, an abscess of the proximal epiphysis of the left humerus was found with the spread of the inflammatory process to the soft tissues of the breast, the parietal pleura with the development of purulent fibrinous pleurisy, left-sided pneumonia, purulent fibrinous pericarditis, hematogenous purulent meningitis.Conclusion. The authors of the article have established a causal cause of death from Brody's abscess, which makes it possible to expand the diagnostic search in the case of sepsis with an unclear primary focus.

Assessing the Influence of Economic Factors on the Dynamics of Exports of Russian Oil and Petroleum Products Based on the Use of a Combination of PEST and SWOT Analysis Methods

The presented work is part of a series of articles devoted to assessing the influence of external factors on the dynamics of Russian exports. In this and subsequent related works, the authors proposed to consider the external environment, which had a significant impact on the dynamics of Russian exports and the relative diffi culty of revising its structure, the basis of commodity exports of which in value terms are hydrocarbon energy carriers. This work represents a conceptual basis for the use of instrumental methods for assessing the influence of external factors, in this case, economic ones, on the integral and sectoral indicators of Russian exports and, in particular, on the export of hydrocarbon energy resources. In the second part of this article, it is proposed to use a set of environmental analysis methods, the basis of which was the previously successfully used mechanism for combining the methods of PESTEL and SWOT analysis, which will make it possible, based on the use of scores, to describe the cumulative influence of external factors on the dynamics of the main industries of Russian exports. The novelty of the presented approach lies in the absence of a methodology for a comprehensive assessment of the influence of external factors on the dynamics of Russian exports using the selected tools, which seems useful and timely in light of the emergence of new political and economic factors that have a significant impact on Russian foreign trade in general and on the dynamics of the carbohydrate energy market , in particular. The parameters for assessing external factors proposed by the authors were chosen by the author independently, taking into account the modern realities of the development of the world economy, which can also represent a separate point of novelty of the research conducted or be part of one of the existing points of novelty of the presented work. The merit of the authors of this work lies in the fact that this work proposed their own vision of a comprehensive assessment of the influence of external factors on the dynamics of the country’s exports.

Development of a New Non-Destructive Analysis Method in Cultural Heritage with Artificial Intelligence

Cultural assets are all movable and immovable assets that have been the subject of social life in historical periods, have unique scientific and cultural value, and are located above ground, underground or underwater. Today, the fact that most of the analyses conducted to understand the technologies of these assets require sampling and that non-destructive methods that allow analysis without taking samples are costly is a problem for cultural heritage workers. In this study, which was prepared to find solutions to national and international problems, it is aimed to develop a non-destructive, cost-minimizing and easy-to-use analysis method. Since this article aimed to develop methodology, the materials were prepared for preliminary research purposes. Therefore, it was limited to four primary colors. These four primary colors were red and yellow ochre, green earth, Egyptian blue and ultramarine blue. These pigments were used with different binders. The produced paints were photographed in natural and artificial light at different light intensities and brought to a 256 × 256 pixel size, and then trained on support vector machine, convolutional neural network, densely connected convolutional network, residual network 50 and visual geometry group 19 models. It was asked whether the trained VGG19 model could classify the paints used in archaeological and artistic works analyzed with instrumental methods in the literature with their real identities. As a result of the test, the model was able to classify paints in artworks from photographs non-destructively with a 99% success rate, similar to the result of the McNemar test.

Validated stability-indicating instrumental thin-layer chromatography method for the quantification of alizarin from Ayurvedic formulations

Validated stability-indicating instrumental thin-layer chromatography method for the quantification of alizarin from Ayurvedic formulations

Studies on How New Quality Productivity Drives High-Quality Development of Enterprises

New quality productivity plays an important role at the macro level, such as in society. But can its impact be observed at the micro level, such as within enterprises? This study builds an enterprise-level index for new quality productive forces and empirically examines its impact on high-quality development in organizations using financial information from A-share listed companies from 2012 to 2022. The empirical findings demonstrate that, at the 1% level, new quality productive forces significantly improves high-quality development in businesses. Robustness tests are performed to further support this finding, which involve substituting the dependent variable and removing anomalous years. To lessen the possibility of endogeneity problems resulting from missing factors or inaccurate measurements in explanatory variables, this study employs the instrumental variable method to mitigate these problems, yielding consistent estimation results. In the current societal context, the findings provide recommendations for further enterprise development. Enterprises should actively enhance technological innovation, improve talent development plans, and optimize management structures to ultimately achieve high-quality development.

Study on the Promotional Effect and Mechanism of New Quality Productive Forces on Green Development

The new quality productive forces have the potential to spur both the green transformation of the industrial structure and innovative advances in green technology, which will further strengthen the foundation for sustainable growth. This study analyzes panel data from 30 provinces between 2012 and 2022 to build an evaluation system for new quality productive forces and green development at the provincial level. The entropy weight TOPSIS approach is used to assign weights to each indicator. Methods including fixed effects, mediation effects, and spatial econometrics are used to examine the contribution of new quality productive forces to green development and its mediation mechanism. The study finds that: (1) New quality productive forces significantly promote green development, and the conclusion still holds after a robustness test using the instrumental variables method and excluding municipalities. (2) The new quality productive forces contribute significantly to green development by improving technology and optimizing industrial structure. (3) The new quality productive forces not only directly enhance the green development level of the region, but also positively influence the green development level of the neighboring regions through the spatial spillover effect. (4) The eastern and central regions are more affected by new productivity in terms of green development. Based on these, efforts should be made to develop new quality productive forces, increase technological research and investment, and promote the development of industrial structure to be more environmentally friendly and efficient to promote green development.

Storm clouds over innovation: Typhoon shocks and corporate R&D activities

This study investigates the economic impact of typhoon disasters on corporate innovation activities, a critical driver of economic growth and resilience. Utilizing a comprehensive dataset of Chinese public companies from 2010 to 2022 and employing a wind field model to construct a city-level typhoon destruction index, we apply difference-in-differences and instrumental variable methods to analyze the effects on corporate innovation. Our findings reveal that typhoon disasters significantly reduce both patent filings and R&D investment intensity, particularly in coastal areas and technology-intensive industries. The adverse effects are transmitted through financial constraints, human capital loss, and infrastructure damage. This research contributes to understanding the microeconomic implications of extreme weather events on innovation-driven economic growth, offering insights for disaster resilience policies in vulnerable regions.

Patient selection for left ventricular assist device implantation. The main problems

To analyze the experience of Chazov National Medical Research Center of Cardiology in patient selection for left ventricular assist device (LVAD) implantation. 901 patients, whose documents were sent to Chazov National Medical Research Center of Cardiology from regional medical and prophylactic institutions, were screened as selection for LVAD implantation. Firstly, all patients underwent transthoracic echocardiography performed according to the extended protocol with a comprehensive assessment of the left and right ventricle size and function. Patients who underwent the screening procedure underwent further examination including both laboratory and instrumental diagnostic methods. In addition, the polyclinic database of patients diagnosed with chronic heart failure (CHF) and dilated cardiomyopathy was also analyzed. Among 901 screened patients 7.9% were suitable candidates for LVAD implantation and only 23 (2.6%) patients underwent surgery. Among those not eligible for surgery: 208 (29%) patients were not on optimal medical therapy, 15% of patients had indications for other surgical treatment of CHF, 12% of patients had severe right ventricular failure, 9.8% had severe comorbidities, 6.8% of patients refused surgery. The main problems of selection for LVAD implantation were: low awareness of doctors about the introduction of new treatment methods, poor quality of transthoracic echocardiography, a large percentage of patients not receiving basic therapy for CHF, untimely referral of patients for other types of surgical treatment.

Orbital dirofilariasis (case report)

Ocular Dirofilariasis is one of the frequent manifestations of this disease. The primary manifestations of dirofilariasis of the visual organ (soreness, redness, itching in the eyelid area) may be nonspecific and weakly expressed at the beginning of the disease. The peculiarity of this disease is that if earlier most cases of human infection with Dirofilaria repens were registered in southern countries and southern regions of the Russian Federation, recently there has been a tendency for this disease to spread to northern regions. Diagnosis of this disease based on the data of instrumental methods of investigation is difficult, although cases of detection of the parasite at the preoperative stage have been described in the literature. This publication presents a clinical case of the orbital form of dirofilariasis, which was diagnosed at the intraoperative stage using transconjunctival access. This access is sufficient for complete removal of the neoplasm, and the rehabilitation of patients after surgery with such an access is short and without the formation of a cosmetic defect. Surgical intervention is the main and only treatment tactic and does not require additional specific antiparasitic treatment.

An alternative instrumental method for studying the morphofunctional state of eyelids in chronic blepharitis

Background: To date, the assessment of morphofunctional changes within eyelids is performed using laser scanning confocal microscopy, which has extensive diagnostic capabilities. Identification of the indicators equivalence of this method and laser Doppler flowmetry will confirm the existence of an alternative, objective and economical method of eyelid examination in chronic blepharitis. Aim: To prove the possibility of laser Doppler flowmetry application as an alternative method of eyelid morphofunctional state assessment. Materials and methods: The study included 62 patients (124 eyes) with an established diagnosis of chronic mixed demodecticosis blepharitis, including 46 women and 16 men, mean age 65.8 ± 3.2 years, randomly assigned into two groups with identical age and gender composition. Group 1 patients (31 patients, 62 eyes) were treated with cosmeceuticals containing terpenes and terpenoids 2 times a day and tear substitute 3 times a day for 1.5 months. Group 2 patients (31 patients, 62 eyes) used an eyelid care gel containing sulphur medicaments 2 times a day and a tear substitute 3 times a day for 1.5 months. In addition to standard ophthalmological examination, laser Doppler flowmetry and laser scanning confocal microscopy were performed. Dynamic follow-up was performed after 1.5 and 3 months. Results: The analysis of laser scanning confocal microscopy and laser Doppler flowmetry parameters revealed a high inverse correlation between the density of inflammatory cells of the eyelids tarsal conjunctiva and neurogenic oscillations of blood flow, as well as high direct correlation with the index of blood flow shunting. A marked direct correlation between the density index of meibomian gland acinuses and the parameters of myogenic oscillations of blood flow and neurogenic oscillations of lymph flow was established. Conclusions: Pearson’s correlation analysis performed on laser scanning confocal microscopy and laser Doppler flowmetry parameters assessing the morphofunctional state of the eyelids demonstrated the presence of equivalence in both study groups with high statistical reliability. The obtained data confirm the possibility of using laser Doppler flowmetry method for objective assessment of eyelid condition and allow the parameters of this method to serve as criteria for choosing pathogenetically oriented therapy of chronic blepharitis with evaluation of its effectiveness.

CAUSES OF PAIN IN THE MUSCLES OF THE LOWER EXTREMITIES IN CHILDREN WITH CEREBRAL PALSY

A high level of muscle spasticity in children with cerebral palsy is one of the causes of degenerative and dystrophic changes in tissues. Against the background of high spasticity, there is a violation of blood flow in the vessels of the lower extremities, which leads to changes in subfascial pressure and the formation of primary pain syndromes. The analysis of the literature shows the need to study the issues related to the mechanism of formation of changes in the muscles and determine the primary causes of pain. Objective. Тo study the mechanism of changes in the muscles of the lower extremities, as well as the primary causes of pain syndrome. Methods. The analysed indicators were obtained during the treatment of 40 patients with cerebral palsy, who were divided into 3 groups depending on the muscle tone disorder. Clinical and instrumental methods were used to examine patients. The data obtained were statistically processed with the determination of M ± m, the coefficient of reliability according to Student’s criteria. Results. According to the results of the study, high spasticity leads to impaired blood flow and increased subfascial pressure in the musculofascial sheaths. There is an inverse correlation between the increase in subfascial pressure, the diameter of the vessel lumen and blood flow velocity. This is one of the causes of degenerative and denervation changes in muscles and fascia. It was proved that the occurrence of primary pain in the lower extremities is caused by various etiological causes: tissue ischemia; increased subfascial pressure; narrowing of pathologically significant anatomical areas in which nerves lie; degenerative and dystrophic changes in the joints. Conclusions. The study found that the cause of changes in the muscles and fascia is a violation of blood flow, a change in subfascial pressure in the musculofascial cases of the lower extremities. The occurrence of pain in the lower extremities in children with cerebral palsy is multifactorial in nature and consists of myofascial, articular, and tunnel syndromes.