Carrier State Research Articles

Occurrence and Phenotypic Characteristics of Methicillin-Resistant Staphylococcus aureus (MRSA) in Emergency Medical Service Ambulances as a Potential Threat to Medical Staff and Patients

Introduction: An ambulance used by an emergency medical service team is the workplace of specialised medical personnel, providing daily transportation for patients in life-threatening conditions, from all walks of life, with numerous diseases and injuries. MRSA (methicillin-resistant Staphylococcus aureus) strains are classified as Gram-positive cocci, characterised primarily by their multidrug resistance. Infections caused by S. aureus have a low treatment success rate and are associated with persistent carrier state. This study aimed to isolate MRSA and MSSA (methicillin-sensitive Staphylococcus aureus) in the emergency vehicle and determine drug resistance of these isolates. Materials and Methods: This study involved an ambulance vehicle operated in central Poland. A total of 39 swabs were taken and evaluated from inside the ambulance on permanent duty. The isolates were analysed using catalase and coagulase assays, Gram staining, culturing on Chapman medium, growth evaluation on agar with 5% sheep blood, and assessing the strains’ sensitivities to selected antibiotics. Material was collected from 13 designated points located in the medical compartment and driver’s cabin. Results: S. aureus bacteria were detected in 51.28% of the samples, 40% of which were MRSA strains. Despite the application of high disinfection standards for the interior of the ambulance, it was not possible to kill all S. aureus strains, which may be because the pathogens in question produce a biofilm that effectively allows them to survive on various surfaces, including those disinfected. Almost 100% of the MRSA isolates were resistant to antibiotics from the β-lactam group (penicillin, ticarcillin, cefotaxime, and cefoxitin), the macrolide group (erythromycin) and the lincosamide group (clindamycin). However, only a few MRSA strains proved resistant to streptomycin (12.5%) and ciprofloxacin (37.5%). β-lactam antibiotics, such as cefotaxime (100% resistant strains) and penicillin (58% resistant strains), were also ineffective against MSSA. Although MSSA isolates showed slight resistance to ticarcillin and erythromycin (33.3%) and clindamycin (25%), the remaining antibiotics proved effective (no resistant strains). Conclusions: Among the isolated strains, the greatest resistance to β-lactam antibiotics and erythromycin was observed. Multidrug-resistant strains of S. aureus were found in the emergency medical system. Even the MSSA strains detected in the studied ambulance showed resistance to some of the antibiotics used. The prevalence of S. aureus strains within ambulances indicates the need for a high hygiene level in daily prehospital work with patients.

Elevated Cerebrospinal Fluid Ubiquitin Carboxyl-Terminal Hydrolase Isozyme L1 in Asymptomatic C9orf72 Hexanucleotide Repeat Expansion Carriers.

To identify biochemical changes in individuals at higher risk of developing amyotrophic lateral sclerosis (ALS) or frontotemporal dementia (FTD) via C9orf72 hexanucleotide repeat expansion (HRE) heterozygosity. Cross-sectional observational study of 48 asymptomatic C9orf72 HRE carriers, 39 asymptomatic non-carrier controls, 19 people with sporadic ALS, 10 with C9orf72 ALS, 14 with sporadic FTD, and 10 with C9orf72 FTD. Relative abundance of 30 pre-defined cerebrospinal fluid biomarkers of ALS and FTD were compared in asymptomatic C9orf72 HRE carriers and age-matched non-carrier controls. Differential abundance of these proteins was quantified using data independent acquisition mass spectrometry or electro chemiluminescent assay for neurofilament light chain. Unbiased analysis of the entire cerebrospinal fluid proteome was then carried out. Ubiquitin carboxyl-hydrolase isozyme L1 levels were higher in asymptomatic C9orf72 HRE carriers compared with age-matched non-carriers (log2fold change 0.20, FDR-adjusted p-value = 0.034), whereas neurofilament light chain levels did not significantly differ. Ubiquitin carboxyl-hydrolase isozyme L1 levels remained elevated after matching of groups by neurofilament levels (p = 0.011), and after adjusting for age, sex, and neurofilament levels. A significant difference was also observed when restricting analysis to younger participants (<37) matched by neurofilament level (p = 0.007). Elevated cerebrospinal fluid ubiquitin carboxyl-hydrolase isozyme L1 levels in C9orf72 HRE carriers can occur in the absence of increased neurofilament levels, potentially reflecting either compensatory or pathogenic mechanisms preceding rapid neuronal loss. This brings forward the window on changes associated with the C9orf72 HRE carrier state, with potential to inform understanding of penetrance and approaches to prevention. ANN NEUROL 2024.

MEGALOBLASTIC CRISIS IN SICKLE CELL DISEASE–A RARE PHENOMENA WITH AVAILABLE REVIEW OF LITERATURE

Sickle cell disease (SCD) is an inherited disease where some red blood cells are shaped like sickles or crescent moons. This condition affects the blood and various organs of the body. These sickle cells also become rigid and sticky, which can slow or block blood flow, resulting in episodes of sickness that produce pain and other crisis. There are different types of crisis. SCD with a megaloblastic crisis is rare. The frequency of the carrier state determines the prevalence of sickle cell anemia. Here we describe a 20 y old female patient with sickle cell disease who experienced a megaloblastic crisis.

Long‐Channel Effects in Randomly Oriented Carbon Nanotube Thin Film Transistors

AbstractCarbon nanotube (CNT) thin film transistors (TFTs) have demonstrated great potential for application in highly sensitive biosensors and large‐area electronics. However, research on the electrical behavior of long‐channel CNT TFTs is lacking; thus, the purposeful improvement in the performance of biosensors or circuits is difficult. In this study, the electrical transport characteristics of ionic‐liquid‐gate CNT TFTs with channel lengths (Lch) ranging from 10 to 400 µm are investigated. The CNT TFTs present classical drift‐diffusion transport at on‐state with a carrier mobility of around 27 cm2 V−1 s−1. In the subthreshold region of the CNT TFTs, an abnormal Lch‐dependent subthreshold swing (SS) relationship, named as the long‐channel effect (LCE)is observed, where SS worsens with increasing Lch. The existence of the junctions between the CNTs results in an unconventional density of states for carriers and a large series resistance for sharing the gate voltage; this dominates the abnormal scaling behavior in the subthreshold region by degrading the electrostatic integrity. The discovery of the abnormal LCE can aid in the construction of device models and purposefully improve the performance of CNT TFTs for biosensors and other large‐scale electronic applications.

Degradation Analysis of Exciplex-Based Organic Light-Emitting Devices Using Carbazole-Based Materials.

A spectral shift and new emission bands in the green and red regions have been observed in deep blue exciplex-based organic light-emitting diodes (OLEDs) using carbazole-based materials, namely, tris(4-carbazoyl-9-ylphenyl)amine (TCTA). To deeply understand the origin of these new bands, single-layer and bilayer TCTA-based OLEDs subjected to electrical and optical (ultraviolet (UV)) stresses were investigated by using various optical, electrical, morphological, and chemical measurements. The results showed that the stress-induced emission bands primarily originate from morphological changes rather than chemical changes. The accumulation of excitons in the TCTA layer induces molecular aggregation, leading to the formation of electrically active electronic states, namely, electroplexes and electromers, which lead to the appearance of additional emission bands in green and red regions. Impedance spectroscopy measurements on single-layer OLEDs complemented this study. The results showed that TCTA degradation affects charge injection and transport. It was concluded that the stress-induced emission bands are caused by aggregate domain formation and are closely linked to the formation of electrically active defects, which act as trap states for charge carriers in the TCTA band gap.

Experiences of family caregivers of children living with thalassaemia-major in Karachi: a phenomenological study

IntroductionThalassaemiamajor, a global health burden, presents a growing challenge in Pakistan’s strained healthcare system. This study explores how caregivers of children with beta-thalassaemia major navigate healthcare services, aiming to identify facilitators and barriers to accessing optimal care.MethodsA qualitative interpretative phenomenological approach was employed. In-depth interviews with 18 purposively sampled caregivers from Karachi thalassaemia centres were conducted. Thematic analysis using a combined inductive-deductive approach identified themes within the interview data.ResultThe study revealed significant challenges for caregivers at individual, interpersonal and organisational levels. Lack of awareness about carrier states, limited disease knowledge, financial constraints and concerns about the child’s future emerged as primary hurdles. Parents felt helpless due to the absence of emotional and social support for their children’s treatment. Obstacles such as complicated registration processes at thalassaemia-care centres, high costs of chelating agents and blood unavailability were major barriers to seeking care and caregiving. Additionally, the study highlighted the absence of guidelines for thalassaemia-carrier detection among mothers during antenatal care.ConclusionThe study emphasised the importance of implementing premarital screening programmes due to the lack of knowledge about the disease and carrier state. To prevent the disease, it is crucial to include thalassaemia-carrier detection for mothers in antenatal guidelines and provide counselling at the primary level. Additionally, caregivers encountered treatment accessibility issues, prompting the establishment of a satellite thalassaemia centre linked to a top-tier tertiary care hospital in the public sector. This initiative addressed treatment challenges and improved overall care for patients with thalassaemia and their caregivers.

When and What to Test for Diarrhea: Focus on Stool Testing.

To review stool diagnostic tests in acute and chronic diarrhea. Narrative review of published literature. (A). In acute diarrhea, stool tests are indicated when there is strong pre-test probability of infectious etiology or C. difficile infection (CDI) suggested by >3 unformed bowel movements per 24h, symptoms lasting >7 days, and circumstances that are suggestive of infection. Several commercially available rapid tests for bacterial, viral or protozoal infections may be offered in addition to traditional methods (e.g. culture, microscopy), and provide a result within 6 hours. For CDI infection, a highly sensitive test such as glutamate dehydrogenase test is required; however, this does not distinguish infection from carrier state. That differentiation requires specialized nucleic acid amplification test (for toxin B) or enzyme immunoassays for toxin A or B, which are unfortunately not generally offered by microbiology labs. (B). Chronic diarrhea may result from inflammatory, fatty, osmotic or secretory causes; the commonest causes are IBS-D/functional diarrhea. Current recommendations in societal guidelines or clinical practice updates regarding stool tests in IBS-D/functional diarrhea in the absence of alarm symptoms include testing for giardia, calprotectin, fecal immunochemical test (FIT), and bile acid diarrhea (BAD). Comprehensive stool biochemical analyses (osmolality, pH, electrolytes) differentiate osmotic from secretory diarrhea and identify laxative abuse. Specific stool diagnostic tests for BAD and exocrine pancreatic insufficiency can lead to specific diagnosis and treatments. Surrogate markers associated with high fecal output and rapid transit in chronic diarrhea are stool form and colonic transit. Fecal testing is still very relevant in the practice of gastroenterology and deserves introduction of advanced microbiological and biochemical tests.

Multidrug-resistant Salmonella Typhi among symptomatic and asymptomatic children in informal settlements in Nairobi, Kenya

BackgroundThe emergence and persistence of multidrug-resistant (MDR) Salmonella Typhi (S. Typhi) infections is a significant global health problem. The carrier state of typhoid makes it prudent to conduct routine surveillance for both acute cases and carriers especially those caused by MDR S. Typhi. We report on the prevalence of MDR S. Typhi, resistance phenotypes and antimicrobial resistance genes detected in symptomatic and asymptomatic children living in informal settlements in Nairobi, Kenya.Methods215 archived presumed S. Typhi isolates from stool samples provided by children ≤ 16 years collected from 2013 to 2018 were revived in May, 2022 and confirmed using culture and antisera serotyping. The Kirby Bauer disc diffusion technique was used to test the S. Typhi against 14 antibiotics. The MDR S. Typhi (resistant to ampicillin, chloramphenicol and sulfamethoxazole trimethoprim) which in addition were also resistant to either a cephalosporin or a fluoroquinolone were analyzed for Beta lactams and quinolone resistance genes using polymerase chain reaction.ResultsA total of 215 isolates were confirmed to be positively S. Typhi; of these, 105 (49%) and 110 (51%) were from symptomatic and asymptomatic children respectively. On average, S. Typhi resistance from asymptomatic and symptomatic children against 1st line drugs was observed at; 77% &70%, ampicillin; 60% & 64%, sulfamethoxazole-trimethoprim, and 45% & 54%, chloramphenicol respectively. Multi drug resistance was observed in 90 (42%) of the isolates, of these, 44 (49%) were isolated from symptomatic and 46 (51%) from asymptomatic children. Fifteen resistance phenotypes (p) were observed with, ampicillin/chloramphenicol/sulfamethoxazole-trimethoprim/nalidixic acid (amp/chl/sxt/na) as the most common among the symptomatic 43/90 (48%) and asymptomatic 55/90 (61%) children. The blaTEM−D, AMR genes were detected in 37/44 (84%) S. Typhi isolates, out of this 18 (49%) were from symptomatic while 19 (51%) were from asymptomatic children respectively.ConclusionThe carriage of MDR S. Typhi among the asymptomatic children is concerning as they can act as potential transmitters of the typhoid disease to unsuspecting children. These study findings highlight the need for continued surveillance of antimicrobial resistance and mass immunization of children living in these urban informal areas.

Advanced Bio-sensing Technologies for Sickle Cell Disease Diagnosis.

Sickle cell diseases are widespread in regions encompassing the Mediterranean, Middle East, sub-Saharan Africa, and specific parts of Asia, primarily due to the abnormal production of hemoglobin S. This genetic blood disorder stems from a mutation in the beta-globin gene, a crucial component of hemoglobin and the heme-containing protein found in red blood cells. Point mutations in the hemoglobin gene can be inherited as a heterozygous or homozygous pattern. These mutations disrupt the normal configuration of the protein, impeding its physiological function and altering the cell's shape, giving it a sickle-like appearance. The resulting sickle cells can lead to organ damage, intense physical discomfort, and anemia; in severe cases, the condition can be fatal. Early detection and effective treatment methods have the potential to progressively reduce the associated mortality rate over time. To diagnose sickle cell disease and its carrier states with unparalleled specificity, a variety of approaches have been developed. The most common method includes differential blood cell counts and their assessment, high-performance liquid chromatography (HPLC) and hemoglobin electrophoresis. Furthermore, innovative sensing technologies are currently under development, encompassing user-friendly, cost-effective and portable point-of-care devices that are capable of timely diagnosis at the genetic and molecular levels of these disorders. The review delves into a range of established and innovative strategies utilized in the detection of sickle cell disease, also underscoring the essential role played by diverse bio-sensing techniques in propelling the advancement of early diagnosis of SCD.

Prevalence and Molecular Characterization of β-Thalassemia in Kirkuk Province of Northern Iraq

To determine the prevalence and molecular basis of β-thalassemia in the Northeastern Iraqi province of Kirkuk, a total of 3954 individuals attending the provincial premarital screening center were recruited. The prevalence of β-thalassemia minor among the screened individuals was found to be 3.0%, while those of Hemoglobin E, and δβ-thalassemia carrier states were 0.05%, and 0.03% respectively. Molecular characterization of the β-thalassemia mutations was achieved by multiplex PCR and reverse hybridization, followed by next generation sequencing for those left uncharacterized by the former technique. Among 19 β-thalassemia mutations identified, seven were the most frequent, namely: IVS-II-1 (G > A), codon 8/9 (+G), IVS-I-6 (T > C), IVS-I-110 (G > A), IVS-I-I (G > A), IVS-I-5 (G > C) and codon 44 (-C) accounting for 78.5% of the mutations. This study further illustrates the heterogeneity of the spectrum of β-thalassemia in different parts of Iraq, and provides an essential step to facilitate prenatal diagnosis in the setting of a future national thalassemia prevention program.

A Rare Case of Homozygous Hemoglobin G-Philadelphia &amp; Alpha Thalassemia

Abstract Introduction/Objective Hemoglobin (Hb) G-Philadelphia (GPh) is an alpha chain gene variant caused by a missense mutation resulting in a change from Glu to Asp at position 68. This change leads to alterations in the Hb structure and oxygen affinity. The mutation is inherited in an autosomal codominant pattern allowing for an asymptomatic carrier state. While the most common alpha chain variant, GPh heterozygosity is still infrequent, estimated at 1:5000 in African Americans. In African Americans, GPh is frequently linked to an alpha thalassemia deletion. On its own it is considered a benign variant that does not result in significant health issues. Homozygous HbGPh frequency is estimated at 1 in 25 million. Methods/Case Report A postpartum woman in her 4th decade of life was found to have a Hb of 10.8 and a mean corpuscular volume of 74. Initial work up included Hb electrophoresis that quantified HbA at 0%, Hb F at 0%, HbA2 at 0%, and 2 Hb variants representing 96.1% and 3.8% of the total globin. The major Hb variant migrated in the D or G position by alkaline and acid gel Hb electrophoresis. The minor variant was consistent with HbG2. Due to this abnormal Hb electrophoresis, a sample was sent out for a Hb evaluation reflexive cascade (HERC). HERC analysis by high-performance liquid chromatography and capillary gel electrophoresis found 99.9% of Hb consistent with the alpha chain variant HbG. Analysis of the alpha globin gene region revealed 2 copies of an alpha globin gene deletion that was interpreted as alpha-thal trait (-a/-a). This result is consistent with homozygous alpha-thal-2 and homozygous HbGPh (alpha^G/thal + alpha^G/thal). Results (if a Case Study enter NA) NA Conclusion Alpha^G/thal + alpha^G/thal presents a unique and complex challenge for diagnosis due to its rarity and because HbG2 is not always visualized by alkaline gel electrophoresis. The presence of a Hb G or D variant, a HbG2 variant, and the lack of both HbA and HbA2 are key electrophoretic findings. Clinically, alpha^G/thal + alpha^G/thal behaves essentially like a homozygous alpha-thal-2 trait with persistent microcytosis and erythrocytosis. Thus, co- inheritance of the alpha-thal trait will be suggested by a thalassemic complete blood count pattern.

Investigation of probable Salmonella outbreak in the National Cancer Institute, Sri Lanka

Abstract Background An outbreak is the occurrence of case of disease in excess of what would normally be expected in a defined community. Outbreaks in immune compromised population can lead to devastating morbidity and mortality. Infection prevention and control (IPC) team has a pivotal role in both averting and managing outbreaks in health care settings. There were 7 cases of Salmonella spp, isolated from blood and stools since 12th July 2023 up to 11th August. Assuming of a possible outbreak, IPC team decided to investigate in order to find a possible source for the outbreak. Methods As soon as the outbreak was confirmed, immediate relevant control measures were taken after studying the available information. Working case definitions was constructed with clinical criteria and laboratory criteria with restrictions by time, place and person. Different categories of case definitions were used as the diagnosis was uncertain, such as “confirmed”, “probable” and “possible”. Active surveillance was conducted to collect information on additional case. Data collection tool was prepared with demographic information, clinical information and risk factor information. Then more cases were detected and line listing was created to organize important information for the investigation. Epidemic curve was drawn to see the pattern of spread and it was an irregularly jagged curve which interprets as intermittent common source epidemic. Specific control and prevention measures were implemented. Inquiries were made regarding the dietary intake of the patients over the last seven days and it was difficult to find a common source of food item however, all patients have consumed food prepared in the hospital kitchen. Therefore an audit was conducted in the hospital kitchen to identify probable source. Kitchen staff was educated about the food safety measures and personal hygiene. Kitchen staff was screened for Salmonella carrier state in their stool. Quality of the water from the kitchen and wards was checked for fecal contamination. No residual food was available for microbiological testing. Hypothesis was formulated to gather information after discussion with patients and staff. Findings were communicated to all relevant parties including Director and clinicians in the hospital. Salmonella isolates were sent to the Enteric Reference Laboratory, Medical Research Institute, Colombo for serotype identification. Results It was difficult find a common source. There were some malpractices in the kitchen and those were corrected immediately. Water quality in the hospital was satisfactory. Kitchen staff were not colonized with salmonella. However egg supplier to the kitchen was changed recently and eggs were supplied last minute and the eggs were not washed prior to cooking. Three isolates sent to the reference laboratory were identified as Salmonella Weltevreden, one as Salmonella Enteritidis, while the remaining three isolates could not be identified to serotype level with the available resources. Conclusion The exact contributory factor to the outbreak remained elusive. However, numerous food safety issues which can lead to cross contamination during the preparation of food were identified. Consequently, prompt investigation and control measures are essential to prevent further food borne outbreaks.

RpoS activates formation of Salmonella Typhi biofilms and drives persistence in the gall bladder.

The development of strategies for targeting the asymptomatic carriage of Salmonella Typhi in chronic typhoid patients has suffered owing to our basic lack of understanding of the molecular mechanisms that enable the formation of S. Typhi biofilms. Traditionally, studies have relied on cholesterol-attached biofilms formed by a closely related serovar, Typhimurium, to mimic multicellular Typhi communities formed on human gallstones. In long-term infections, S. Typhi adopts the biofilm lifestyle to persist in vivo and survive in the carrier state, ultimately leading to the spread of infections via the fecal-oral route of transmission. In the present work, we studied S. Typhi biofilms directly, applied targeted as well as genome-wide genetic approaches to uncover unique biofilm components that do not conform to the CsgD-dependent pathway established in S. Typhimurium. We undertook a genome-wide Tn5 mutation screen in H58, a clinically relevant multidrug resistance strain of S. Typhi, in gallstone-mimicking conditions. We generated New Generation Sequencing libraries based on the ClickSeq technology to identify the key regulators, IraP and RpoS, and the matrix components Sth fimbriae, Vi capsule and lipopolysaccharide. We discovered that the starvation sigma factor, RpoS, was required for the transcriptional activation of matrix-encoding genes in vitro, and for S. Typhi colonization in persistent infections in vivo, using a heterologous fish larval model. An rpoS null mutant failed to colonize the gall bladder in chronic zebrafish infections. Overall, our work uncovered a novel RpoS-driven, CsgD-independent paradigm for the formation of cholesterol-attached Typhi biofilms, and emphasized the role(s) of stress signaling pathways for adaptation in chronic infections. Our identification of the biofilm regulators in S. Typhi paves the way for the development of drugs against typhoid carriage, which will ultimately control the increased incidence of gall bladder cancer in typhoid carriers.

Influenza B Triggering Atypical Hemolytic Uremic Syndrome (aHUS) in a Patient with Cobalamin C (CblC) Disease Carrier State and a Complement Factor H (CFH) Mutation

Influenza B Triggering Atypical Hemolytic Uremic Syndrome (aHUS) in a Patient with Cobalamin C (CblC) Disease Carrier State and a Complement Factor H (CFH) Mutation

Prioritizing disease-related rare variants by integrating gene expression data.

Rare variants, comprising the vast majority of human genetic variations, are likely to have more deleterious impact in the context of human diseases compared to common variants. Here we present carrier statistic, a statistical framework to prioritize disease-related rare variants by integrating gene expression data. By quantifying the impact of rare variants on gene expression, carrier statistic can prioritize those rare variants that have large functional consequence in the patients. Through simulation studies and analyzing real multi-omics dataset, we demonstrated that carrier statistic is applicable in studies with limited sample size (a few hundreds) and achieves substantially higher sensitivity than existing rare variants association methods. Application to Alzheimer's disease reveals 16 rare variants within 15 genes with extreme carrier statistics. We also found strong excess of rare variants among the top prioritized genes in patients compared to that in healthy individuals. The carrier statistic method can be applied to various rare variant types and is adaptable to other omics data modalities, offering a powerful tool for investigating the molecular mechanisms underlying complex diseases.

Serological Investigation for Brucella ceti in Cetaceans from the Northwestern Mediterranean Sea.

Neurobrucellosis in cetaceans, caused by Brucella ceti, is a relevant cause of death in striped dolphins (Stenella coeruleoalba) from the Mediterranean Sea. Serological tests are not used as a routinary technique for the diagnosis of this infection. We briefly describe the pathological findings of nine free-ranging stranded cetaceans diagnosed with Brucella disease or infection in our veterinary necropsy service from 2012 to 2022. The findings included focal diskospondylitis and non-suppurative meningitis, choroiditis and radiculitis. Additionally, an exploratory serological study was conducted in sixty-six frozen sera collected in the period 2012-2022 from fifty-seven striped dolphins, five Risso's dolphins (Grampus griseus), two common bottlenose dolphins (Tursiops truncatus), one common dolphin (Delphinus delphis) and one pilot whale (Globicephala melas) to compare antibody levels in Brucella-infected (n = 8) and non-infected (n = 58) animals, classified by the cause of death, sex, age class and cetacean morbillivirus (CeMV) infection status. The authors hypothesized that active infection in cases of neurobrucellosis would elicit a stronger, detectable humoral response compared to subclinical infections. We performed a commercial competition ELISA (cELISA) using serial serum dilutions for each sample, considering a percentage of inhibition (PI) of ≥40% as positive. A titer of 1:160 was arbitrarily determined as the seropositivity threshold. Seropositive species included striped dolphins and Risso's dolphins. Seroprevalence was higher in animals with neurobrucellosis (87.5%) compared to the overall seroprevalence (31.8%) and to other causes of death, indicating, likely, a high sensitivity but low specificity for neurobrucellosis. Animals with chronic CeMV seemed to have higher seroprevalences, as well as juveniles, which also had a higher disease prevalence. These results indicate, as in other studies, that antibodies are not decisive against clinical brucellosis, although they may indicate a carrier state, and that CeMV may influence Brucella epidemiology. More research is required to elucidate the epidemiology and pathogenesis and to resolve the complicated host-pathogen interaction in Brucella species.

Complex dynamics in nonlinear small time-delayed optoelectronic oscillator and application in fast reservoir computing and pulse generation

We investigated a time-delayed optoelectronic oscillator (OEO) that displays a wide range of complex dynamic behavior under small time delay. The phase-space trajectory distributions in different dynamic regimes were compared which brings a new perspective on the underlying mechanism of the transition process. It was found that bifurcation is always possible no matter how small the time delay is even if the universal adiabatic approximation model is invalid. Hereby we proposed a versatile simple oscillator which has a potential capacity as memory carrier and high-dimensional state spatial mapping ability that brings 1000 times computing-efficiency improvements of reservoir computing over the large time delay one. Furthermore, we demonstrated a new approach for a tunable optoelectronic pulse generator (repetition rate at 0.2 MHz and 0.25 GHz) which depends critically on time-delayed input electrical pulse. The proposed oscillator is also a promising system for the applications of fast chaos-based communication.

(Invited) Influence of the Semiconductor Thin Film Morphologies on Dntt Organic Electronic Devices Performances

Interest in organic semiconductors has grown enormously in the last few years, indeed their use in microelectronics is continuously rising up in a large range of fields, spanning from academic to industrial new applications [1]. They provide a large number of interesting properties that have pushed a gradual replacement of classical amorphous silicon-based devices with organic ones [2], as they promise to be the best candidates as drivers of the necessary green and digital transition and become the building blocks in a huge number of future applications.In most devices, particularly in OTFTs, the quality and properties of the interface between semiconductor and dielectric are of fundamental importance for the device electrical characteristics [3-4]. Dinaphtho [2,3-b:2′,3′-f] thieno [3,2-b] thiophene (DNTT)-based OTFTs are among the best-known devices as they provide good performances in terms of charge mobility, good stability as well as easy processing and they are particularly suitable to study deeper the role of insulator/semiconductor interface [5-6]. It has been widely reported that the best performances of the small molecule organic based transistors, in terms of charge mobility as well as stability, are obtained when the molecules align with their long axis almost perpendicular to the growth surface. The DNTT molecules deposited on SiO2, align to form a homogeneous film, which results to be highly crystalline and provides good transport properties. However, in DNTT-based OTFTs different insulator surfaces, above which the active layer is grown, can provide different properties in terms of morphology and surface energy so that the electrical performances of the resulted devices can span in a wide range [7].In this work, we have studied the growth of DNTT semiconductor thin films on two different dielectric materials relating the ordered DNTT thin film structure to the OTFTs' electrical characteristics. OTFTs have been fabricated with Bottom Gate Top Contact (BGTC) configuration using thermal SiO2 or a double layer of SiO2/CytopTM as gate dielectrics. Semiconductor thin films, with thicknesses ranging from 3 nm to 50 nm, were detailed analyzed with high resolution AFM and XRD measurements (Fig. 1a, b, c, d) for different growth conditions to understand the morphologies of the films starting by the very first ordered layers of DNTT semiconductors. Our measurements show that DNTT molecules on SiO2 and Cytop pack into ordered structures placing themselves with their long axis perpendicular to the plane of the substrate (edge-on). However, in the case of DNTT on SiO2, a portion of ordered molecules can lie horizontally on the substrate (face-on). This causes an increase of defective states for the majority carriers in the conductive channel of the transistor, with a consequent reduction of the field-effect mobility (Fig. 1a, b). Numerical simulations were performed to analyze the effects of different semiconductor film morphologies on the electrical characteristics of the OTFTs. We also show that the morphological semiconductor differences lead to better performances for organic phototransistors based on DNTT/Cytop interface [8].[1] C. Wang et al., Chemical reviews 2012, 112 (4), 2208-2267.[2] Y. Bonnassieux et al., Flexible and Printed Electronics 2021, 6 (2), 023001.[3] H. I. Un et al., Advanced Science 2019, 6 (20), 1900375.[4] H. Sirringhaus et al., Advanced materials 2014, 26 (9), 1319-1335.[5] H. Chang et al., Org. Electron., 2015, 22, 86-91.[6] Q. Wang et al., ACS applied materials & interfaces 2018, 10 (26), 22513-22519.[7] M. Geiger et al., Advanced Materials Interfaces 2020, 7 (10), 1902145.[8] S. Calvi, et al., Org. Electron., 2022, 102, 106452. Figure 1

STUDY OF THE COMBINED EFFECT OF POST-SYNTHETIC ALKALINE TREATMENT AND NICKEL MODIFICATION OF MFI ZEOLITE ON THE DYNAMICS OF ITS DEACTIVATION IN THE PROCESS OF REFINING STRAIGHT-RUN GASOLINE

To determine the combined effect of post-synthetic treatments on the catalytic properties of MFI type zeolite (other names ZSM-5 or pentasil) during the upgrading of straight-run gasoline fraction of oil, MFI zeolite was synthesized and on its basis a sample was obtained, treated with an alkaline solution, as well as a nickel-containing sample after alkaline treatment of the zeolite. Modification of zeolite powder treated with an alkaline solution with nanosized nickel powder was carried out by dry mechanical mixing of the original powders in a vibrating mill. The activity and dynamics of deactivation of the obtained zeolite catalysts during the upgrading of straight-run gasoline fraction of oil were studied. Along with determining the characteristics of the target reaction products - high-octane gasoline, an analysis of the resulting gaseous hydrocarbons was carried out and the amount of carbon compaction products was determined. It has been shown that post-synthetic treatments of zeolite have a positive effect on the qualitative composition and yield of catalysates and reduce the rate of deactivation of zeolite catalysts. Post-synthetic alkaline treatment of MFI zeolite significantly reduces its aromatizing and cracking activity, resulting in an increased yield of high-octane gasoline with improved environmental characteristics. The introduction of nickel nanopowder into alkali-treated zeolite further enhances this tendency. Carrying out post-synthetic treatments of zeolite increases the time of stable operation of the resulting zeolite systems in the process of upgrading straight-run gasoline and reduces the amount of carbon compaction products formed. The state, location and dimensions of the zeolite carrier, nickel particles and carbon compaction products were determined using the transmission electron microscopy method. It has been shown that oxidative regeneration of a carbonized catalyst makes it possible to almost completely remove the resulting carbon deposits from the surface of both the active component and the zeolite support. For citation: Velichkina L.M., Gerasimov E.Yu., Vosmerikov A.V. Study of the combined effect of post-synthetic alkaline treatment and nickel modification of MFI zeolite on the dynamics of its deactivation in the process of refining straight-run gasoline. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2024. V. 67. N 8. P. 103-112. DOI: 10.6060/ivkkt.20246708.10t.

Prevalence of Staphylococcus aureus in saliva of healthcare workers

Background: The carrier state of methicillin-resistant Staphylococcus aureus is pointed as an infection predictor and a factor for environmental and person-to-person dissemination, including health service workers. These, when colonized are commonly associated to outbreaks. Objective: Analyze the prevalence of Staphylococcus aureus in saliva of workers at a university hospital. Methodology: Epidemiologic longitudinal study carried out in Curitiba, Paraná, Brazil, with 486 workers between April 2006 and June 2008. Three saliva samples were collected and a data collection instrument was applied. Staphylococcus aureus were isolated from the clinical specimen and characterized by phenotypes. The data from the instrument and the laboratory results were organized and processed with EPI-Info software and analyzed via descriptive statistics. Results: Among the healthcare workers studied, 60.9% were colonized by Staphylococcus aureus in saliva; of those, 67.9% were transitory carriers and 32.1% were persistent carriers; the prevalence of meticillin-resistant Staphylococcus aureus (MRSA) among the isolated cases was 15.7%. The average prevalence of MRSA was 12.7% and higher among nurses’ aides (21.4%) and cleaning aides (20.6%) and lower among nurses (4.5%) and doctors (5.9%). Conclusions: Healthcare workers presented high prevalence of Staphylococcus aureus in saliva, indicating the mouth as an important body site to investigate colonization by MRSA and a potential source to its dissemination.