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The need to increase the productivity and capacity of power transformers has conditioned the production of insulating papers of a higher thermal class. For this purpose, various techniques of solid insulation modification were applied, which enable the increase in thermal and chemical stability of the insulating paper during the operation of the transformer. The applied additives, primarily dicyandiamide (DICY) and polyacrylamide (PAM), are one form of cellulose modification in the final stages of paper production. A significant difference between the papers is the nitrogen content in the paper, which is characterized by the addition of amine compounds (additives). The paper presents the application of infrared spectroscopy with totally attenuated reflection (FTIR-ATR) in the characterization of paper samples. The aim is to observe the difference between regularly kraft and thermally upgraded paper reflected in the presence or absence of characteristic functional groups for additives. The strip identification at 2194-2154 cm-1 confirmed the presence of dicyandiamide additives (DICY) in the spectrum of the sample of thermally upgraded paper, which is different compared with the spectrum of regular kraft paper.

Modern experimental research theory includes plans for statistical multifactorial analysis. The advantage of this theory is that all factors are changed simultaneously so that a minimum number of experimental points distributed in the experimental hyperspace is obtained, which results in much lower costs and shorter time of experimental tests. The process of decontamination of polychlorinated biphenyls (PCB) from transformer oils is based on a dechlorination reaction using a reagent mixture (KPEG) consisting of potassium hydroxide (KOH) and polyethylene glycol (PEG), whereby the PCB molecule is chemically decomposed. Using 23 orthogonal plans, the influence of the mass ratio of KPEG/oil, KOH/PEG molar ratio and temperature on the dechlorination reaction were investigated to optimize this process. The success of the reaction was evaluated by determining the efficiency of chemical degradation of PCBs (DRE) from transformer oil. The DRE values were from 81.81% to 99.81%. Using dispersion analysis, the significance and degree of interactivity of the examined factors on DRE were determined, and using regression analysis, a multilinear regression model was set up.

This paper provides a literature review and establishes the state-of-the-art in the concept and application of Digital Twin (DT) technology to power transformers. The introductory sections focus on the evolving definition and universal concepts of DT, independent of specific fields of application, as well as the goals of Industry 4.0 and the technologies that enable digital transformation in industry. Special attention is given to the particularities of the power industry, with an emphasis on the unique requirements posed by the nature and importance of oil-filled power transformers, which serve as the foundation for the development of systems based on DT technologies.

The project funded by the Science Fund of the Republic of Serbia, Development of Green Technology to Mitigate Power Transformer Failures Induced by Elemental Sulphur and Change Current Hazardous Practice in Transformer Oil Regeneration, under the acronym GreenCleanS focuses on developing a new technology for removing elemental sulphur molecule (S₈) from mineral insulating oils used in power transformers (PT) utilization an innovative low-temperature desulfurization process. The technology development includes experimental work at the laboratory scale and pilot scale level (technology readiness level, TRL 4), as well as the demonstration of the technology in an operational environment, involving the treatment of 3 tons of oil in a mobile desulfurization unit to achieve TRL 7. The implementation of this innovative technology will contribute to reducing the number of transformer failures caused by mineral oils containing S₈, a highly corrosive compound.

The aim of the study was to test the potential of immunostimulating Limosilactobacillus fermentum BGHI14 strain to reduce the damage of colon tissue in rats with 2,4,6trinitrobenzenesulfonic acid (TNBS)-induced colitis. Wistar rats were treated with L. fermentum BGHI14 in the regime of preventive, therapeutic and continuous treatment 22 days prior to and/or 7 days after the administration of TNBS. After sacrifice, the colon tissue samples were taken for RNA isolation, gene expression analysis, histopathological analysis, and malondialdehyde measurement. Judging from the body weights, histopathological scores, malondialdehyde levels and transcription of IL-1b and Tight junction protein 1 (Tjp-1) coding genes, preventive and therapeutic treatment proved to be the most protective in the applied conditions. On the other hand, continuous treatment did not affect the intensity of tissue damage. Considering these results, we discussed the possible mechanisms which might stand behind the protective action of immunostimulating probiotic bacteria in the case of mucosal barrier damage.

In parallel with the significant reduction of the impact of vehicles on the environment, the development of modern propulsion systems that have less and less harmful impact, new pollutants are being identified on the vehicle. One of the such pollutants is the brakes, which wear out and lead to the formation of particles that are released into the air, i.e. generally into the environment. Investigation of the mechanism of particle formation during braking, and thus the brake wear is today becoming one of the important areas of research. The most common tests in this area are performed using initial brake dynamometers and pin-on-disc machines. An overview of the influence of some operation parameters (initial vehicle speed, braking pressure, and deceleration) that varies frequently during testing on an inertial brake dynamometer is performed in this paper. There are a number of tests and cycles that are applied during research, but they are not specifically prescribed for testing the particle formation during braking. The UNECE (United Nations Economic Commission for Europe) has included it in its plan and is in the development phase of introducing standardized cycles that will prescribe the braking cycle, the purpose of which will be to examine the formation of particles. This kind of review paper can be important for researchers who are engaged in this field, and the develop their own cycles or tests to examine the concentration or mass of particles formed during braking.

The Republic of Serbia signed and ratified the Stockholm Convention on Persistent Organic Pollutants. Law on ratification of the Stockholm Convention was adopted and actions were defined through the National Implementation Plan and the Action Plan. On their basis Project Proper Management and Final Disposal of Polychlorinated Biphenyls (PCBs) was created. Institute Nikola Tesla (INT) participated in the realization of the project. In the period from 2015 to 2022, 601 tons of PCB oil was successfully decontaminated by the INT mobile plant, i.e. the PCB content was below 50 mg/kg, which classified the power transformers (PT) as non-contaminated [1,2]. If PT becomes waste or in case of necessary repair or oil regeneration, the required limit value is 10 mg/kg. According to data from INT database there are still 2637 PTs containing PCBs in the concentration range of 2 to 50 mg/kg. In this paper application of the environmentally closed INT decontamination technology for achieving low values of PCB in the oil is shown.

Most power transformer failures are associated with the presence of corrosive sulfur compounds in mineral insulating oil, of which dibenzyl disulfide (DBDS) is the best known and most widespread corrosive sulfur compound. The oil of failed transformers usually contained DBDS, a compound with a pronounced affinity for the formation of copper (I) sulfide (Cu2S). Copper (I) sulfide is a compound that does not dissolve in oil, conducts electricity, and can be deposited on the paper insulation or copper conductor of the transformer. Created conductive paths between the windings can initiate turn-to-turn breakdown and failure of the transformer. Several technological procedures have been developed as a solution to oil corrosivity. The application of desulfurization technology developed by the Electrical Engineering Institute "Nikola Tesla" enables the efficient removal of DBDS and aging products from mineral insulation oils.

Revenues generated by football clubs belonging to one of the socalled "The Big Five" leagues (England, Germany, Spain, Italy and France) give a strong argument by claiming that modern football has become a very organized, but also profitable business. In the football clubs of the mentioned European countries, the most famous players of today are "super heroes" and they are the reason why massive numbers of football fans visit football stadiums. All players, who today identify themselves as elite athletes, were at the beginning of their sports careers merely talented individuals with more or less pronounced psycho-physical predispositions for playing sports. This paper will present the basic characteristics of the profession of professional scouts as one of the key persons in recognizing talents and their transformation into top athletes. Also, the paper emphasizes the necessary skills that these sports experts should possess, but also points out the importance of decisionmaking in terms of often difficult and complicated decisions in the process of identifying talented individuals in sports.

The reliability of power transformers operation largely depends on the insulation system condition, especially on the condition of paper insulation. Determining the condition of paper insulation of transformers in use cannot be made by direct measurements. The most common way of assessing the paper insulation condition is by analyzing the content of 2-furfural dissolved in the insulating oil and by applying correlations between the degree of paper polymerization and the 2-furfural content in the insulating oil. The concentration of 2-furfural in the oil depends on the moisture content of the insulation system and the oxygen and acid content in the oil. In order to gain a better insight into the cumulative content of 2-furfural produced by paper degradation, excluding changes in the 2-furfural content caused by migration between paper and oil at different operating temperatures, dependence of the degree of polymerization of kraft paper to 2-FAL content in the oil, corrected to a reference temperature of 20°C, for a moisture content in cellulose of 1-1.5% and 3-4% is presented in this paper. This diagram has been verified on 4 transformers according to available data from the database of the Electrical Engineering Institute Nikola Tesla. In the future, this diagram should be completed for moisture content of 2.5% in cellulose insulation.

Employers are increasingly faced with the need to identify, attract, hire and retain the best talent from the labor market in order to survive in the condition of fierce competition. As talents are in a position to choose an employer, successful companies seek to position themselves as ideal and desirable employers through the establishment of a strong employer brand. In the process of brand establishing, by applying the knowledge from the field of marketing and human resources, employers tend to position themselves to labor market candidates as unique and desirable with ideal working conditions, while at the same time trying to increase the level of satisfaction and dedication of existing employees. A modern approach to the process of branding an employer implies taking into account the needs and desires of different generation of employees. A generation that takes an important position in society and labor market - millennium generation (also known as the generation Y) has specific needs, demands and desires when it comes to selecting an employer. In this paper are point out the key specifics of establishing employer brand in order to position it as an ideal place for talents that belong to the generation of millennials.

City branding has a strategic dimension. When it comes to defining city branding strategy, creating city brand personality, that is, defining a set of human characteristics that are connected to city brand, is particularly important. In this way, a city can increase its recognisability and differentiate itself from the competition on location market. The main aim of this work is to show the experience of defining city brand personality within the project 'Vranje as a brand'. In the first part of the research, we used quantitative techniques (residents and visitors of Vranje were surveyed), while in the second part qualitative techniques were applied (focus group). On this occasion, the results of the research were complemented with the personality elements, that were taken from the literary works of the famous Serbian writer Borisav Stanković, who was born in Vranje and whose literature is connected with this city. That gave an additional element of authenticity to the brand personality. This is an example of how art can shape city personality, or discover the attributes which describe this personality.

The exploitation of PCB contaminated power transformers and those which contain corrosive sulphur is related to the greatest risks to the environment, due to possible environmental accidents and faults and failures of transformers. The equipment contaminated with PCB require special attention, more frequent testing of transformer condition and control of oil leaking, while for corrosive oils standards and requirements defined in CIGRE TB 378, CIGRE TB 625, IEC 60296 and IEC 60422 are restrictive for the use of corrosive oils. Overview of the problems with PCB contaminated equipment and corrosive sulphur is provided in accordance to the latest knowledge in these areas. PCB decontamination, desulfurization and oil regeneration process is described by the application of patented technology developed in the 'Nikola Tesla' Institute. Summarized results of decontamination process of 310 PCB contaminated power transformers with different voltage levels and power and removal of corrosive sulphur from 29 transformers show the efficiency of this process for simultaneous removal of PCB, corrosive sulphur and oil ageing products.

The Fourth Industrial Revolution has brought significant changes in the field of organizational design, especially in terms of how work is structured, organized, and conducted. One of the major trends widely adopted by numerous businesses worldwide is the establishment of virtual project teams, which allows members to work from remote locations regardless of their time zone, nation or culture and to collaborate using various information systems and technologies. Advantages of virtual project teams observed in terms of cost reduction, productivity growth, knowledge, skills, and flexibility are obvious and cannot be neglected. Nevertheless, challenges do often appear, and need to be addressed in order to create successful virtual organizations. The objective of this paper is to examine the role and importance of trust in virtual project teams, and to propose methods and activities that can help establish and nurture trust among employees in remote teams.

Background/Aim. Preeclampsia (PE) belongs to the group of hypertensive disorders in pregnancy with the global average incidence of 2.16%. It is considered as one of the leading causes of maternal and neonatal morbidity and mortality worldwide. The goal of this study was to assess the potential association between Val158Met catechol-o-methyltransferase (COMT), tumor necrosis factor-alpha (TNF-α) -857 C>T, tumor necrosis factor receptor 1 (TNFR1) 36 A>G, interleukin-1alpha (IL-1α) 4845 G>T and interleukin-10 (IL-10) -1082 A>G polymorphisms and risk of early-onset preeclampsia (PE) and its complications. Methods. The study included 47 early-onset PE patients, which were grouped by disease severity and by size for gestational age and 47 control cases. The Val158Met polymorphism was genotyped by polymerase chain reaction – restriction fragment length polymorphism (PCR-RFLP) analysis and inflammatory cytokine polymorphisms by the Sanger sequencing method. Results. The COMT Met allele as well as IL-1α T showed a protective role, decreasing the risk of early-onset PE after age and body mass index (BMI) adjustments. The detected interactions between the COMT Met and IL-10 A alleles, as well as between the COMT Met and TNF-α T alleles were insignificant after age and BMI adjustments. Conclusion. COMT and IL-1α may be used as candidate genes for early-onset PE and its severe form and small for gestational age (SGA) complications.

Background: Up until now there have been contradictory data about the association between p.Val158Met catecholO-methyltransferase (COMT) polymorphism and risk of preeclampsia (PE). The goal of this study was to assess the potential correlation between p.Val158Met COMT polymorphism and risk of early-onset PE, risk of a severe form of early-onset PE, as well as risk of small-for-gestationalage (SGA) complicating PE. Methods: The study included 47 early-onset PE patients and 47 control cases. Forty-seven early-onset PE patients were grouped by disease severity (33 patients with a severe form and 14 patients without severe features) and secondly by size for gestational age (12 patients with appropriate-for-gestational-age (AGA) and 35 patients with SGA size). p.Val158Met polymorphism was genotyped by PCR-RFLP analysis. Results: Allele analysis showed significant difference in COM T allele distribution between early-onset PE and control group as well as early-onset PE SGA and controls (p= 0.04057 and p=0.0411 respectively). A statistically significant distribution difference between the severe form and form without severe features of early-onset PE patients was not observed (p> 0.05). The highest difference observed was in the allele recessive model where COMT MetMet genotype was associated with decreased risk of early-onset PE (O R = 0.281; 95%CI = 0 .092-0.7836) and PE complications including severe early-onset PE (OR= 0.304; 95% C I= 0.086-0.944) and SGA early-onset PE (O R = 0.284; 95% C I= 0.081-0.874). Conclusions: COMT may be used as a candidate gene for early-onset PE and its severe form and SGA complications.

A novel design of a circuit used for NTC thermistor linearization is proposed. The novelty of the proposed design consists in a specific combination of two linearization circuits, a serial-parallel resistive voltage divider and a two-stage piecewise linear analog-to-digital converter. At the output of the first linearization circuit the quasi-linear voltage is obtained. To remove the residual voltage nonlinearity, the second linearization circuit, i.e., a two-stage piecewise linear analog-to-digital converter is employed. This circuit is composed of two flash analog-to-digital converters. The first analog-to-digital converter is piecewise linear and it is actually performing the linearization, while the second analog-to-digital converter is linear and it is performing the reduction of the quantization error introduced by the first converter. After the linearization is performed, the maximal absolute value of a difference between the measured and real temperatures is 0.014°C for the temperature range between −25 and 75°C, and 0.001°C for the temperature range between 10 and 40°C.

This paper describes an adaptive Internet application for the interpretation of the transformer oil gas chromatographic analysis results. The first version of the application is developed by following an evolutionary software development concept. The most important software development risks and the appropriate solutions are described. An open-source web framework named Bootstrap is used for an application implementation. The application is developed by using ASP.NET and MS SQL server.

This paper describes a system within an oil aging test device that serves for measurement and automatic regulation of gas flow. Following an already realized system that continuously monitors, logs, and regulates transformer oil temperature during the aging process and maintains temperature consistency within strict limits, a model of a flow meter and regulator of air or oxygen through transformer oil samples is developed. A special feature of the implemented system is the measurement of very small gas flows. A short technical description of the realized system is given with a functional block diagram. The basic technical characteristics of the system are specified, and the operating principles and application of the system are described. The paper also gives performance test results in a real exploitation environment.

The information necessary to make important decisions is held by many different hierarchical levels in organizations and management needs to find the answer on the question should the decisions be centralized and made by the top management or decentralized and made by the managers and employees of the lower-level units. This question becomes more important in the big data era which is characterized by volume, velocity, and variety of data. The aim of this paper is to analyze whether information and communication technology leads to centralization or decentralization tendencies in organizations and to give answer on the question what are the new challenges of decision making process in the big data era. The conclusion is that information and communication technology provides all organizational level with information that traditionally was used by only few levels, reducing internal coordination costs and enabling organizations to allow decision making across a higher range of hierarchical levels. But final decision of allocation of decision rights depends on knowledge of employees, especially in the big data era, where professionals with new knowledge and skills (known as data scientist) became of tremendous importance.

The aim of this paper is to explore the impact of information technology (IT) on organization including all elements that are integral part of organizational design through Star Model (Kates and Galbraith, 2007), and to show that IT has become an important strategic resource that provides a concentration of all relevant information for quality decision-making and integration of complex organization with the concept of “Big Data” (Manyika et al, 2011). In order to achieve the aim, research was performed in organization in the health sector which affects the quality of life and standard of living. TheIT impact on organizational design and through him on organizational effectiveness in the health care is visible and provide insight into the implications of information technology and opportunities for reasoning about matters that are the subject of research: whether and how information technology causes changes in the design of the organization; whether it affects all elements of design equally; on which elements has the most intense impact and why; whether and why employees and users of health services exhibit resistance to information technology; under what conditions can be reduced or completely eliminated the resistance of employees and users of health services?

Intracellular pathogens including Staphylococcus aureus contribute to the non-healing phenotype of chronic wounds. Lactobacilli, well known as beneficial bacteria, are also reported to modulate the immune system, yet their role in cutaneous immunity remains largely unknown. We explored the therapeutic potential of bacteria-free postbiotics, bioactive lysates of lactobacilli, to reduce intracellular S. aureus colonization and promote healing. Fourteen postbiotics derived from various lactobacilli species were screened, and Latilactobacillus curvatus BGMK2-41 was selected for further analysis based on the most efficient ability to reduce intracellular infection by S. aureus diabetic foot ulcer clinical isolate and S. aureus USA300. Treatment of both infected keratinocytes in vitro and infected human skin ex vivo with BGMK2-41 postbiotic cleared S. aureus. Keratinocytes treated in vitro with BGMK2-41 upregulated expression of antimicrobial response genes, of which DEFB4, ANG, and RNASE7 were also found upregulated in treated ex vivo human skin together with CAMP exclusively upregulated ex vivo. Furthermore, BGMK2-41 postbiotic treatment has a multifaceted impact on the wound healing process. Treatment of keratinocytes stimulated cell migration and the expression of tight junction proteins, while in ex vivo human skin BGMK2-41 increased expression of anti-inflammatory cytokine IL-10, promoted re-epithelialization, and restored the epidermal barrier via upregulation of tight junction proteins. Together, this provides a potential therapeutic approach for persistent intracellular S. aureus infections., (© 2024 The Author(s). The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.)

Hybrid halide perovskites are attractive candidates for resistive switching memories in neuromorphic computing applications due to their mixed ionic-electronic conductivity. Moreover, their exceptional optoelectronic characteristics make them effective as semiconductors in photovoltaics, opening perspectives for self-powered memory elements. These devices, however, remain unexploited, which is related to the variability in their switching characteristics, weak endurance, and retention, which limit their performance and practical use. To address this challenge, we applied low-dimensional perovskite capping layers onto 3D mixed halide perovskites using two perfluoroarene organic cations, namely (perfluorobenzyl)ammonium and (perfluoro-1,4-phenylene)dimethylammonium iodide, forming Ruddlesden-Popper and Dion-Jacobson 2D perovskite phases, respectively. The corresponding mixed-dimensional perovskite heterostructures were used to fabricate resistive switching memories based on perovskite solar cell architectures, showing that the devices based on perfluoroarene heterostructures exhibited enhanced performance and stability in inert and ambient air atmosphere. This opens perspectives for multidimensional perovskite materials in durable self-powered memory elements in the future.

The pandemic caused by the SARS-CoV-2 virus had a great impact on the population of patients treated with peritoneal dialysis (PD). This study demonstrates the impact of infection and vaccination in 66 patients treated with PD and their outcomes during a 6-month follow-up. This is the first research that has studied the dynamics of anti-SARS-CoV-2 IgG in serum and effluent. In our research, 57.6% of PD patients were vaccinated, predominantly with Sinopharm (81.6%), which was also the most frequently administered vaccine in the Republic of Serbia at the beginning of immunization. During the monitoring period, the level of anti-SARS-CoV-2 IgG antibodies in the PD patients had an increasing trend in serum. In the group of vaccinated patients with PD, anti-SARS-CoV-2 IgG antibodies had an increasing trend in both serum and effluent, in contrast to non-vaccinated patients, where they decreased in effluent regardless of the trend of increase in serum, but statistical significance was not reached. In contrast to vaccinated (immunized) patients who did not acquire infection, the patients who only underwent the COVID-19 infection, but were not immunized, were more prone to reinfection upon the outbreak of a new viral strain, yet without severe clinical presentation and with no need for hospital treatment.

This study aimed to evaluate different commercial diets (Otohime C1, Aller Futura (AF), Biomar Inicio Plus (BIP)) and one experimental feed (EF) in terms of their effectiveness as post-larval diets for indoor weaned largemouth bass, LMB ( Micropterus salmoides ). Key variations in the content of nutritive values were monounsaturated fatty acid (MUFA) and highly unsaturated FA (HUFA) ω3. Fish were fed with one of four tested diets from the 33rd to the 40th day post-hatch (DPH). Biometric indices, digestive enzyme-specific activities, thyroid hormone status, and mRNA expression of genes coding for skeleton, neuron, and muscle growth were analyzed. The lowest skeletal deformity rate and highest survival among the treatments were seen in BIP-fed fish. Dietary lipids, with an appropriate balance between MUFA and polyunsaturated FA (PUFA), alongside amino acid balance, were shown to be the main contributors to the growth of the skeleton and/or fish survival. On the other hand, fish growth is correlated with fish digestive capacity and feed moisture percent rather than feed quality. Unexpectedly, BIP-fed fish were attributed with the lowest expression of skeleton differentiation markers, which may reflect the sacrifice of scale and/or cranium growth at the expense of somatic growth. This study highlights the role of non-marine ingredients in the nutrition of post-larval LMB.

Dispersive liquid-liquid microextraction (DLLME) using a floating organic drop has been optimized and used for the sample preparation of four commonly used ultraviolet filter (UVF) substances in sunscreens. Plackett-Burman experimental design was used to screen 10 variables in DLLME. The most significant variables were then optimized by using a response surface method with a Box-Behnken design. DLLME followed by an optimized HPLC identified octocrylene, 2-ethylhexyl-4-methoxycinnamate, ethylhexyl salicylate, and homosalate as the frequently found UVFs in commercial sunscreens. The systemic exposure dosage and margin of safety (MoS) for the identified UVFs were estimated using in-use concentrations and application patterns. The average systemic exposure dosage values for octocrylene, 2-ethylhexyl-4-methoxycinnamate, ethylhexyl salicylate, and homosalate were 0.52, 0.61, 0.020, and 0.079 mg/kg body weight per day, respectively. Whereas the average MoS values for individual UVFs ranging from 296 to 3160 were all significantly higher than the limit value of 100, the combined exposure risks were slightly above the limit. The probabilistic health risk assessment using Monte Carlo simulation revealed that the combined MoS values were (mean, 10‰, 90‰) 342, 119, and 441, respectively. Regarding the usage of sunscreen cosmetics containing the UVFs studied, these results indicate a safety concern for those who apply multiple UVF products., (© 2023 John Wiley & Sons Ltd.)

A fast and straightforward reversed-phase dispersive liquid-liquid microextraction (RP-DLLME) using a deep eutectic solvent (DES) procedure to determine free tryptophan in vegetable oils was developed. The influence of eight variables affecting the RP-DLLME efficiency has been studied by a multivariate approach. A Plackett-Burman design for screening the most influential variables followed by a central composite response surface methodology led to an optimum RP-DLLME setup for a 1 g oil sample: 9 mL hexane as the diluting solvent, vortex extraction with 0.45 mL of DES (choline chloride-urea) at 40 °C, without addition of salt, and centrifugation at 6000 rpm for 4.0 min. The reconstituted extract was directly injected into a high-performance liquid chromatography (HPLC) system working in the diode array mode. At the studied concentration levels, the obtained method detection limits (MDL) was 11 mg/kg, linearity in matrix-matched standards was R 2 ≥ 0.997, relative standard deviations (RSD) was 7.8%, and average recovery was 93%. The combined use of the recently developed DES -based RP-DLLME and HPLC provides an innovative, efficient, cost-effective, and more sustainable method for the extraction and quantification of free tryptophan in oily food matrices. The method was employed to analyze cold-pressed oils from nine vegetables (Brazil nut, almond, cashew, hazelnut, peanut, pumpkin, sesame, sunflower, and walnut) for the first time. The results showed that free tryptophan was present in the range of 11-38 mg/100 g. This article is important for its contributions to the field of food analysis, and for its development of a new and efficient method for the determination of free tryptophan in complex matrices, which has the potential to be applied to other analytes and sample types.