Institute for Medical Research, Serbia

BACKGROUND Bacterial spot caused by Xanthomonas spp. is considered an economically important disease affecting pepper. Considering that antibiotics‐based treatments in disease control are forbidden in European countries, biological control has emerged as a promising approach. RESULTS In this study, we demonstrated high biological efficacy of three indigenous pepper seed‐associated Bacillus spp. – Bacillus velezensis (P64), Bacillus safensis (P114), and Bacillus halotolerans (P122) – in the control of Xanthomonas euvesicatoria. Two independent trials based on the pepper growth in pots and in the field resulted in similar performances in terms of disease spread reduction (as calculated by disease incidence and disease severity index) over time compared to the untreated controls. In both trials, treatments included initial preventive or curative applications of these biocontrol bacteria once the secondary apical lateral shoot became visible (BBCH 29), followed by additional application at the beginning of flowering (BBCH 52–55). Ratings conducted at 7‐day intervals after the first treatment indicated very high biological efficacy, typically exceeding 80%. All three strains remained active throughout the assessment period, whereby their efficacy started to increase 21 days after the first treatment, reaching 99.59% after 49 days. Although bacterium B. velezensis is already known for its beneficial role in the control of plant bacterial diseases, this is among the first study demonstrating the bactericidal activity of B. safensis and B. halotolerans. CONCLUSION The current research outlines a promising novel approach for X. euvesicatoria control in pepper based on the type of microbial agents as well as the timing of their application. © 2025 Society of Chemical Industry.

Red currant (Ribes rubrum L.) berries are rich in bioactive compounds and exhibit nutritive and protective features. This research examined the content of secondary metabolites of the red currant variety Redpoll lyophilized juice and waste extract and their antioxidative and spasmolytic effects. The flavonol and anthocyanin contents of the samples were determined using high-performance liquid chromatography. The antispasmodic effects were assessed in in vitro conditions, and the potential impact of the samples and possible action mechanisms were revealed. The results showed the prevalence of cyanidin-3-O-glucoside as the dominant anthocyanin with higher content in the juice sample. Quercetin content, as the prevalent flavonol, was higher in the waste sample. The berry juice showed a greater ability for scavenging free radicals, whereas the waste better inhibited lipid peroxidation. The juice was a superior antispasmodic agent for spontaneous, KCl-, CaCl2-, BaCl2-, histamine-, and acetylcholine-induced ileal contractions. This first evaluation of the red currant variety Redpoll lyophilized juice and waste extract indicated the beneficial effects of juice as an antioxidant and spasmolytic agent. Therefore, this red currant juice sample could be designated for the prevention or treatment of gastrointestinal disorders.

Introduction Qualitative and quantitative testing of ethanol in post-mortem samples is an important analytical procedure that provides accurate, precise, and reliable results. Given the complexity of the issue, obtaining a realistic picture of lifelong alcoholemia requires supporting blood ethanol findings with analyses of alternative samples, primarily vitreous humor (VH). Objective The objective of this study was to develop and validate a headspace gas chromatography with flame ionization detection (HS/GC-FID) method for determining ethanol concentration in VH. Materials and methods Conditions for the HS/GC-FID method were established and the method was validated according to the guidelines of the European Medicines Agency. Validation parameters such as precision, accuracy, specificity, sensitivity, and linearity over a wide concentration range were evaluated through statistical analysis. Results The method demonstrated precision, accuracy, specificity, and sensitivity. Additionally, it proved to be linear across a wide concentration range and relatively fast, making it suitable for rapid and routine determination of ethanol concentration in VH, particularly for forensic applications. Conclusion Results from validation and application of the method to VH samples indicate that ethanol concentration in VH can be reliably determined using the presented HS/GC-FID method, making it a valuable tool in forensic investigations.

Background Apical periodontitis is caused by infected dental pulp and may be associated with dental caries or trauma, which can destroy periradicular tissues. This study included periapical tissue of patients with chronic apical periodontitis and aimed to evaluate the presence of cytomegalovirus (CMV) and Epstein-Barr virus (EBV) using polymerase chain reaction (PCR), and to determine the levels of inflammatory cytokines using enzyme-linked immunoassay (ELISA). Material/Methods A total of 79 patients participated in this study. Periapical lesions were taken from the tooth roots indicated for extraction, and were divided into 2 groups: symptomatic and asymptomatic. PCR was used to identify HCMV and EBV. Interleukin 6 (IL-6), interleukin 8 (IL-8), tumor necrosis factor-alpha (TNF-α), and transforming growth factor beta-1 (TGFβ-1) were determined using ELISA. Results The occurrence of HCMV (P<0.05) and dual HCMV/EBV infection (P<0.05) was significantly more frequent in symptomatic lesions compared to asymptomatic. The concentrations of IL-6, IL-8, and TNF-α were significantly higher in virus-positive lesions compared to virus-negative ones (P<0.05); especially high cytokine levels were found in lesions with dual HCMV/EBV infection (P<0.05). The level of TGF-β1 was higher in virus-positive compared to virus-negative lesions, but the difference was significant only in lesions with dual HCMV/EBV infection (P<0.05). Conclusions The higher prevalence of herpesviruses in symptomatic lesions compared to asymptomatic ones indicates their important role in pathogenesis of periapical lesions. Expression of TNF-α, IL-6, and IL-8 may be of importance in the development and clinical features of herpesvirus-infected lesions, while TGF-β1 appears to be of no significance.

The osteogenic process is a complex and dynamic biological phenomenon essential for the initial formation of bones during embryonic development and the continuous remodeling and repair of bones throughout an individual’s life. It involves coordination of various cell types, signaling pathways, and environmental factors to ensure proper bone formation and maintenance. The main role in this process belongs to bone marrow cells and peripheral blood cells. This paper provides an overview of currently available literature data about different contributions of bone marrow cells and peripheral blood cells to the osteogenic process. Focusing on their differentiation, signaling pathways, and interactions within the bone microenvironment this article aims to provide a comprehensive understanding of how these cells orchestrate the osteogenic process, offering insights into their therapeutic potential. Understanding these complex cellular interactions is crucial for the development of advanced therapeutic approaches in regenerative medicine and orthopedics, which will ultimately improve outcomes in patients with bone defects and bone-related disorders.

Schizophrenia (SCH) is a major mental illness that causes impaired cognitive function and long-term disability, so the requirements for reliable biomarkers for early diagnosis and therapy of SCH are essential. The objective of this work was an untargeted lipidomic study of serum samples from a Serbian cohort including 30 schizophrenia (SCH) patients and 31 non-psychiatric control (C) individuals by applying liquid chromatography (LC) coupled with high-resolution mass spectrometry (HRMS) and chemometric analyses. Principal component analysis (PCA) of all samples indicated no clear separation between SCH and C groups but indicated clear gender separation in the C group. Multivariate statistical analyses (PCA and orthogonal partial least squares discriminant analysis (OPLS-DA)) of gender-differentiated SCH and C groups established forty-nine differential lipids in the differentiation of male SCH (SCH-M) patients and male controls (C-M), while sixty putative biomarkers were identified in the differentiation of female SCH patients (SCH-F) and female controls (C-F). Lipidomic study of gender-differentiated groups, between SCH-M and C-M and between SCH-F and C-F groups, confirmed that lipids metabolism was altered and the content of the majority of the most affected lipid classes, glycerophospholipids (GP), sphingolipids (SP), glycerolipids (GL) and fatty acids (FA), was decreased compared to controls. From differential lipid metabolites with higher content in both SCH-M and SCH-F patients groups compared to their non-psychiatric controls, there were four common lipid molecules: ceramides Cer 34:2, and Cer 34:1, lysophosphatidylcholine LPC 16:0 and triacylglycerol TG 48:2. Significant alteration of lipids metabolism confirmed the importance of metabolic pathways in the pathogenesis of schizophrenia.

The contribution of certain occupational and personal factors to the development of carpal tunnel syndrome (CTS) is still uncertain. We investigated which specific occupational and non-occupational factors correlate with the level of clinical manifestations and work disability related to CTS. The study included 190 workers who work with a computer and have diagnosed CTS (100 men, 90 women, aged 20–65 years). Subjective experience of CTS-related impairments was assessed with the Symptom Severity Scale (SSS) and the Functional Status Scale (FSS) of the Boston Carpal Tunnel Syndrome Questionnaire (BCTQ). The objective, neural impairments were tested with electrodiagnostics (EDX), whereas CTS-related work disability data were collected from medical records. We found a high inter-correlation between BCTQ, EDX, and work disability data. These also showed high correlations with certain occupational factors (duration of computer-working in months and hours spent daily in computer-working, certain ergonomic, microclimatic, and other occupational conditions) and non-occupational factors (demographic and lifestyle factors: nutritional status, diet, smoking, alcohol consumption, and physical activity). Despite its limitations, our study has identified occupational and non-occupational risk factors that can aggravate CTS and work disability, but which can also be improved with workplace and lifestyle preventive and corrective measures. More research is needed, though, to establish the possible causal relationships and the independent influence of each of those risk factors.

NT-proBNP is marker of acute heart failure. Recent investigation implicate its role in different cardiac and non-cardiac diseases and different mechanism of release in patients with STEMI and NSTEMI. Our study included 66 patients with diagnosis of acute myocardial infarction, hospitalized in Clinical Centre Kragujevac. We evaluated standard biochemical analysis including NTproBNP, electrocardiography, transthoracic echocardiography and coronary angiography. The most common cardiovascular risk factors were emotional stress (93,94%), and physical inactivity( 81,82%). NT-proBNP values were higher in patients with AMI vs health volunteers (943 vs. 162,5 pg/ml, p = 0,0001), NSTEMI vs STEMI patients (1427 pg/ml vs. 592 pg/m, p = 0,005), patients with culprit lesion on left vs right coronary artery (1421 vs. 548, p =0.02), and anterior vs inferior location AMI (1714vs. 625, p =0.022). We found positive correlation NT-proBNP values with CRP, urea, creatinine, and negative correlation with triglicerides, hemoglobin, left ventricular ejection fraction. Higher values of NT-proBNP values are recorded in patients with AMI, NSTEMI, anterior location AMI and with culprit lesion on left coronary artery.

Oxidative stress status and morphological injuries in the brain of Wistar rats induced by repeated application of selected acetylcholinesterase reactivators - asoxime, obidoxime, K027, K048, K074, and K075 were evaluated. Each oxime in a dose of 0.1 of LD50/kg im was given 2x/week for 4 weeks. Markers of lipid peroxidation (malondialdehyde, MDA), and protein oxidation (advanced oxidation protein products, AOPP), as well as the activity of antioxidant enzymes (catalase, CAT, superoxide dismutase, SOD, glutathione reductase, GR, and glutathione peroxidase, GPx), were estimated in the brain tissue homogenates on day 35 of the study. Brain alterations were carefully quantified by semiquantitative grading scales - brain damage score (BDS). Oxidative stress parameters, MDA and AOPP were significantly highest in the asoxime-, obidoxime- and K075-treated groups (p < 0.001). The activity of SOD and CAT was significantly elevated in the obidoxime-, K048-, and K075-treated groups (p < 0.001). Besides, GR was markedly decreased in the obidoxime- and K074-treated groups (p < 0.01), while treatment with K048, K074 and K075 induced extremely high elevation in GPx levels (p ˂ 0.001). In the same groups of rats, brain alterations associated with polymorphonuclear cell infiltrate were significantly more severe than those observed in animals receiving only asoxime or K027 (p < 0.001). The presented results confirmed that treatment with different oximes significantly improved the oxidative status and attenuated signs of inflammation in rats' brains. Presented results, together with our previously published data can help to predict likely adverse systemic toxic effects, and target organ systems, which are crucial for establishing risk categories, as well as in dose selection of K-oximes as drug candidates.

Objective This study aims to explore the changes in blood lipid levels, body composition, and blood pressure in healthy middle-aged overweight people with mild hypercholesterolemia following the 45-day intake of a dietary supplement containing both glucomannan and red rice extract. Design and method The survey was designed as a single-arm non-randomized, non-blind intervention study. 31 study participants consumed a dietary supplement containing dietary fibers (Konjak glucomannan, E425ii) and red rice extract (Monascus purpureus) for 45 days. Participants were asked not to change their current diet. Their body weight, body composition, and blood pressure were measured every two weeks. Blood lipids were tested at the beginning and at the end of the intervention. Results After 45 days, there was a significant decrease in total cholesterol (by 16-18%), LDL cholesterol (by 20-24%), and triglyceride levels (by 11-23%) in both genders. In addition, women lost on average about 1 kilogram of body weight, 1.5 kilograms in body fat, and decreased their body mass index by 0.5 kg/m ² . No changes in body composition were observed among men, but their systolic pressure decreased by six mmHg on average. Conclusions Concurrent use of glucomannan and red yeast rice extract resulted in a significant reduction in blood lipid levels in both genders. It could be a safe and effective treatment option for the population of healthy middle-aged overweight people with mild hypercholesterolemia.

Background: The cannabis plant or marijuana has been used since ancient times for different purposes. An increase in the content of THC in cannabis has been observed worldwide, whereas the CBD content is dropping. This study’s main goal was to categorize marijuana suspected policies’ seizures (MSPS) based on the cannabinoid component concentrations concerning their potency and age. Methods: The samples were MSPS seized in southeast Serbia from April 2019 to April 2020. The cannabinoid content was determined using gas chromatography with mass spectrometry. Descriptive statistics were performed using Linux LibreOffice Calc. Results: All of the samples had a THC content higher than 0.3%, thus classifying the samples as marijuana according to the Serbian Law on Psychoactive Controlled Substances. The highest concentration of THC was 16.10%, while the lowest was 4.90%. The highest average concentration of THC (12.39%) was found in the buds. Only 11.81% of the samples had a CBD concentration higher than 1%, making all other marijuana samples extremely psychoactive. Most of the samples were older than 2 years, according to the calculated CBN/THC ratio. Conclusion: Our results confirm trends regarding the dominance of THC content in contemporary cannabis worldwide. It is necessary to monitor trends of cannabis potency in Serbia continuously because of its location.

Background: The aim of this cross-sectional study was to compare the levels of inflammatory mediators in nasal secretions in patients with aspirin-exacerbated respiratory disease (AERD) and in those with nasal polyposis (NP) without aspirin-sensitivity and to correlate nasal fluid mediator concentrations with clinical parameters of the disease. Methods: A total of 30 patients with AERD, 30 chronic rhinosinusitis (CRS) with NP patients without aspirin sensitivity (CRSwNP), and 30 control subjects without inflammation of the nasal mucosa (C), selected for surgical treatment entered the study. The total nasal symptom score (TNSS), endoscopic score (ES), and Lund-Mackay score (LMS), were evaluated. The concentrations of eosinophil cationic protein (ECP), tryptase, heat shock protein 70 (HSP70), substance P and Clara cell protein 16 (CC16) were determined in nasal secretions. Results: Higher concentrations of ECP, tryptase, and HSP70 were measured in the AERD patients than in the CRSwNP patients and the C group (p < .001; p < .001, respectively for all mediators). However, levels of CC16 were higher in the C group than in the AERD and CRSwNP groups (p < .001; p < .001, respectively). A positive correlation between the TNSS and CC16 and a negative one between CC16 and tryptase levels were found in the C group. The CRSwNP group showed positive correlations between ECP, HSP70, and tryptase and negative correlations between substance P, ES, and LMS, as well as between CC16 and tryptase levels. In the AERD group, we found a positive correlation between HSP70 and ECP levels and a negative correlation between the TNSS and CC16 concentration. Conclusion: The obtained results indicate the increased production of mediators of eosinophil and mast cell function, and the decreased production of biomarker of respiratory epithelial function in AERD patients. Clinical and biochemical parameters correlate in different ways in the AERD and CRSwNP patients.

Background/Aim. Impaired vision resulting from glaucoma can have deleterious effects on both physical and mental health. This study aims to examine the adverse im-pacts of primary open-angle glaucoma (POAG), primary angle closure glaucoma (PACG), and pseudoexfoliation glaucoma (PEG) on the quality of life (QoL) in Central Serbia. Methods. This research, designed as a cross-sectional study, included 102 patients treated for POAG, PACG, or PEG. The patients were divided into three groups (POAG, PACG, and PEG) based on the type of glaucoma they suffered from and were monitored for six months. The data on the QoL were obtained with the National Eye Institute Visual Functioning Questionnaire 25 (NEI VFQ-25). Using the appropriate algorithm, the total NEI VFQ-25 scores were calculated for each group. Results. The questionnaire showed that scores for general vision were significantly lower in the PEG group than in the other two groups (PEG: 61.1 ? 12.6; POAG: 71.6 ? 17.9; PACG: 75.7 ? 11.6), p < 0.001. General health, eye pain, distance vision, social functioning, peripheral vision, reduced ability in daily activities, and dependence on others were also statistically significantly lower in the PEG group. The highest value of near vision was recorded for the POAG group (76.2 ? 21.2). The highest mean value in glaucomatous visual field defect was recorded in the PEG group (14.5 ? 3.6 dB). Conclusion. This research has demonstrated that the QoL is significantly lower in patients suffering from PEG compared to those suffering from POAG and PACG. Concerning the general health of patients, eye pain, distance vision, as well as the domain of social and everyday functioning, the lowest scores for individual areas of examination according to the NEI VFQ-25 were recorded in PEG patients. The results indicate that serious measures should be taken in order to improve the QoL of glaucoma patients.

As the existing data on the correlation of adiposity with adverse outcomes of carotid endarterectomy (CEA) are inconsistent, the aim of the present study is to examine the correlation of an increased body mass index with 30-day complications after carotid endarterectomy. The cohort study comprises 1586 CEAs, performed at the Clinic for Vascular Surgery in Belgrade, from 2012–2017. Out of them, 550 CEAs were performed in patients with normal body mass index (18.5–24.9), 750 in overweight (25.0–29.9), and 286 in obese (≥30) patients. The association of overweight and obesity with early outcomes of carotid endarterectomy was assessed using univariate and multivariate logistic regression analysis. Overweight patients, in whom CEAs were performed, were significantly more frequently males, compared to normal weight patients–Odds Ratio (OR) 1.51 (95% confidence interval– 1.19–1.89). Moreover, overweight patients significantly more frequently had non-insulin-dependent diabetes mellitus—OR 1.44 (1.09–1.90), and more frequently used ACEI in hospital discharge therapy—OR 1.41 (1.07–1.84) than normal weight patients. Additionally, the CEAs in them were less frequently followed by bleedings—OR 0.37 (0.16–0.83). Compared to normal weight patients, obese patients were significantly younger—OR 0.98 (0.96–0.99), and with insulin-dependent and non-insulin-dependent diabetes mellitus—OR 1.83 (1.09–3.06) and OR 2.13 (1.50–3.01) respectively. They also more frequently had increased triglyceride levels–OR 1.36 (1.01–1.83), and more frequently used oral anticoagulants in therapy before the surgery–OR 2.16 (1.11–4.19). According to the results obtained, overweight and obesity were not associated with an increased death rate, transient ischemic attack (TIA), stroke, myocardial infarction, or with minor complications, and the need for reoperation after carotid endarterectomy. The only exception was bleeding, which was significantly less frequent after CEA in overweight compared to normal weight patients.

Introduction/Background Fertility sparing treatments of cervical cancer have pushed the idea of overall cervical cancer surgical treatment perhaps becoming less radical due to low risk of parametrial involvement in patients with early stage I cervical tumors, and the benefit from parametrial resection being debatable. Determining factors predicting parametrial tumor spread and defining those at risk of recurrence still remain highly questionable. Methodology We reviewed patients with stages IA2 and small IB1, who had all undergone radical hysterectomy with pelvic lymph node dissection treatment for cervical cancer, and analyzed factors contributing to parametrial cancer spread. Results A total 980 patients treated for cervical cancer were reviewed, 279 with tumors smaller than 20 mm in diameter. Parametrial spread was detected in 10 patients (3.6%); 1.3% in parametrial lymph nodes, 1,8% in parametrial lymphovascular space, and0.9% as parametrial contiguous microscopic tumor spread. In 94.6% patients with negative pelvic nodes, none had parametrialnodal involvement, 0.9% had LVSI, and 0.4% had contiguous spread. Factors associated with parametrial disease were deep cervical invasion, lymphovascular space invasion (LVSI), tumor volume, and pelvic lymph node metastases. In patients without LVSI and superficial third tumor invasion, parametrial spread was identified in 0.5%. Conclusion The risk of recurrence in 1 out of 200 patients still persists even in low risk small volume cervical cancer patients. Patients willing to accept this risk most likely as fertility sparing options must be clearly consented to this possibility of cancer recurrence which might likely be untreatable.

Objectives Biomarker levels in nasal secretions can reflect the inflammatory status of nasal mucosa and evolution of sinus disease. The aim of this study was to evaluate the relationship between local inflammatory mediator production and clinical characteristics of patients with nasal polyposis (NP). Methods Thirty‐one nonaeroallergen sensitized patients with NP (NANP), 29 aeroallergen sensitized patients with NP (ANP), and 30 subjects without inflammation of nasal mucosa as controls (C) entered this prospective, cross‐sectional study. Clinical parameters (symptoms, endoscopic, and radiological findings) were assessed. The concentrations of heat shock protein 70 (HSP70), eosinophil cationic protein (ECP), tryptase, substance P and Clara cell protein 16 (CC16) were measured in the nasal secretion samples of all participants by ELISA method. Results Our results showed higher concentrations of HSP70, ECP, and tryptase in ANP than in NANP and C (p < .001 for all markers). On the other hand, levels of CC16 were significantly higher in C than in NANP and ANP groups (p < .001; p < .001, respectively). We found positive correlations between HSP70, ECP, tryptase, and substance P levels and nasal symptom score in patients with NP. Also, HSP70, ECP, tryptase, and substance P showed different levels of positive correlation among themselves, with HSP70 showing highest positive correlation with ECP. Finally, relatively strong negative correlations were found between the levels of CC16 and nasal symptoms, as well as between the CC16 levels and levels of other four mediators in nasal fluid. Conclusion HSP70, ECP, tryptase, and substance P might play a role in the pathogenesis of NP. The results suggest that chronic inflammation in NP involves a self‐sustaining local release of HSP70, ECP, and tryptase, independent of aeroallergen stimulation of the mucosal layer, although the production of these mediators is higher in aeroallergen sensitized NP patients.

Background The aim of this study was to determine which standard preoperative laboratory results correlate to intraoperative transfusion requirement during orthotopic liver transplantation (OLT). Materials and Methods We retrospectively analyzed data from 305 adult patients who underwent OLT between 2009 and 2013 using laboratory results: International Normalization Ratio, platelet count, fibrinogen, and hemoglobin and total blood transfusion requirements (group L ≤ 1 L, group M > 1 L). All statistical analyses were conducted using the Statistical Package for Social Sciences software (IBM Corp. Released 2012. IBM SPSS for Windows, Version 21.0; IBM Corp., Armonk, NY, United States). Results We found a positive correlation with hemoglobin and fibrinogen using multivariate analysis (P < .001). The receiver operating characteristic analysis in favor of total blood replacement > 1 L has shown a correlation with fibrinogen (cut-off value of 2.3 g/L, sensitivity of 85.8%, and specificity of 37.4%) and hemoglobin (cut-off 111 g/L, sensitivity of 69.9%, and specificity of 71.6%). Discussion and Conclusion This study has confirmed that preoperative fibrinogen and hemoglobin level, but not International Normalization Ratio and platelet count, are indicators of potential massive perioperative blood loss during OLT and that within our patient cohort a cut-off fibrinogen value of 2.3 g/L and Hb level of 110g/L can predict a blood replacement of >1 L.

Host–guest electron transfer (HGET) in molecular framework systems is a critical trigger for drastic functional changes in both host framework and guest. A reversible magnetic phase transition was achieved via HGET in a layered framework, [{Ru2(2,6‐F2PhCO2)4}2(BTDA‐TCNQ)] (1), where 2,6‐F2PhCO2⁻ and BTDA‐TCNQ represent 2,6‐difluorobenzoate and bis[1,2,5]dithiazolotetracyanoquinodimethane, respectively. The guest‐free 1 with an antiferromagnetic ground state transformed into a paramagnet, [{Ru2(2,6‐F2PhCO2)4}2(BTDA‐TCNQ)]I3 (1‐I3), by adsorbing iodine (I2). The local charge distribution of [{Ru2II,III}⁺‐(BTDA‐TCNQ).−‐{Ru2II,II}] in 1 was reversibly modified to [{Ru2II,III}⁺‐(BTDA‐TCNQ)⁰‐{Ru2II,II}](I3⁻) in 1‐I3 through HGET. Theoretical calculations of 1‐I3 indicated a partial charge delocalization as [{Ru2}(1−δ)+‐(BTDA‐TCNQ)⁰‐{Ru2}δ+](I3⁻) with δ≈0.2, aided by weak ferromagnetic coupling. 1‐I3 exhibited a hundred‐fold enhancement in electrical conductivity compared to that of 1.