Manufacturing of Bellows Compensator by Pulsed-Magnetic Field Pressure

Bellows are a cylindrical shell with a corrugated part, widely used in aviation engineering as a movable sealing element to balance pressure and temperature differences, which ensure continuous and accurate system operation. The use of bellows expansion joints provides reliable and effective protection of pipelines from static and dynamic loads arising from deformations and vibration. Welded-edge bellows are a popular choice for regulating and controlling fuel supply in aircraft devices. The ability of the compensator to perceive deformations is determined by its assigned operating time, which describes how many cycles, and with what amplitude, the bellows compensator perceives without damage. A method for stamping bellows from tubular billets by using magnetic-pulse field in rigid dies, including sequential shaping of corrugations by distributing the internal magnetic pressure with axial movement of the free end of a tubular billet, characterized in that the material of the tubular billet for shaping corrugations is selected in accordance with its relative elongation.

Prevalence of High-Risk Antibiotic Resistant Acinetobacter baumannii in the Holy Cities of Makkah and Al-Madinah

Background: Acinetobacter baumannii strains resistant to carbapenems are a global public health problem. Objectives: The aim of the present study is to evaluate the prevalence of genetic fingerprints associated with Metallo β-lactamases in A. baumannii in addition to the clonal diversity of A. baumannii in Makkah and Al-Madinah regions of Saudi Arabia, which receive a high number of international visitors. Methods: Multi-antibiotic resistant A. baumannii isolates were investigated. Bacterial isolation was conducted employing a basic bacteriological technique after confirming the ID of isolates. The antimicrobial susceptibility test was carried out using the Vitek 2 compact system. The molecular clonal diversity of the isolates was determined by Pulse Field Gel Electrophoresis (PFGE). Clusters were analyzed with BioNumerics software version 6.5. Dice coefficient was used for calculating the similarities. Results: The results indicated resistance in 82.5% of A. baumannii isolates against the carbapenems. All the isolates were found to be sensitive to colistin, while 5% of isolates were resistant to tigecycline. The screening of carbapenem-resistant A. baumannii isolates showed that the dissemination of imipenem and meropenem resistance was 81 and 84%, respectively, while the majority of the strains were susceptible to tigecycline and colistin. The blaOXA and blaVIM were the most encountered genes in A. baumannii isolates, while ISAba1 was the prominent insertion sequence. The genetic fingerprinting results (PFGE) revealed two types of epidemic clones: monoclonal and polyclonal models of 17 clusters. Conclusion: The current investigation indicates the diversity in genetic fingerprints of carbapenem-resistant A. baumannii in Makkah and Al-Madinah region of Saudi Arabia, and that two types of epidemic clones are present. It has also been demonstrated that such clones create serious infection dissemination to other parts of the world as heavy pilgrimage traffic is received throughout the year in Makkah and Al-Madinah, especially in the Haj season.

Salmonella enterica 4,[5],12:i:- an emerging threat for the swine feed and pork production industry

Salmonella continues to be a significant cause of foodborne illnesses in human medicine. The Centers for Disease Control and Prevention reported Salmonella as the second leading cause of foodborne illness in the United States, and the leading cause of both hospitalizations and deaths. Salmonella enterica 4,[5],12:i:- (STM) is a monophasic variant of S. Typhimurium and it is an emerging threat to both human and animal health. STM was first identified in the 1980’s from poultry products and has become increasingly prevalent in meat products including pork. STM has also been identified in swine farms as well as feed manufacturing environments and feed itself. Similar pulse-field gel electrophoresis profiles have been observed between human clinical cases and the STM samples originating from swine feed. These related profiles suggest a link between swine ingesting contaminated feed and the source of foodborne illness in human. The objective of this article was to better understand the history of STM and the possible pathway between swine feed to the household table. Continued research is necessary to better understand how STM can enter both the feed supply chain and the pork production chain to avoid contamination of pork products destined for human consumption.

On the possibility of averaging the equations of an electron motion in the intense laser radiation

The problem of averaging of the relativistic motion equations of electron in the intense laser radiation, caused by the decreasing of the rate of wave phase change due to the Dopplers effect, is considered. As a result the phase can go from the fast to slow variables of the motion, so averaging over the phase becomes impossible. An analysis is presented of the conditions which are necessary for averaging of the relativistic equations of motion over the fast phase of the intense laser radiation on the base of the general principles of the averaging method. Laser radiation is considered in the paraxial approximation, where the ratio of the laser beam waist to the Rayleigh length is accepted as a small parameter. It is supposed that the laser pulse duration is of the order if the laser beam waist. In this case first-order corrections to the vectors of the laser pulse field should be taken into account. The general criterion for the possibility of the averaging of the relativistic motion equations of electron in the intense laser radiation is obtained. It is shown that an averaged description of the relativistic motion of an electron is possible in the case of a fairly moderate (relativistic) intensity and relatively wide laser beams. The known in the literature analogical criterion has been obtained earlier on the base of the numerical results.

A Highly Sensitive and Miniature Optical Fiber Sensor for Electromagnetic Pulse Fields

The detection of an electromagnetic pulse (EMP) field is of great significance in determining the field environment of tested equipment in small spaces. Finger-shaped miniature optical fiber sensors for electromagnetic pulse field measurement were designed. The antenna of a weak field sensor was integrated with a shielding shell, and the wire welded at the direct electro-optic converting circuit connected to an optical fiber through special structure and circuit design was taken as the antenna of a strong field sensor. Measurements in the time domain and frequency domain had been carried out for the two sensors. Experiment results demonstrate that the weak field sensor and the strong field sensor have flat responses from 100 kHz to 1 GHz with a variation of 2.3 dB and 2.9 dB, respectively, and the EMP waveform detected by the sensors agrees well with the applied standard square wave. Moreover, the strong field sensor exhibits linear responses from 645 V/m to 83 kV/m. The resolution of the weak field sensor is as low as 13 V/m. The result indicated that the designed sensors had good performance.

Origin and Dissemination of Altered El Tor Vibrio cholerae O1 Causing Cholera in Odisha, India: Two and Half Decade’s View

The origin, spread and molecular epidemiology of altered El Tor Vibrio cholerae O1 strains isolated from cholera outbreaks/surveillance studies between 1995 and 2019 from different district of Odisha were analyzed. The stock cultures of V. cholerae O1 strains from 1995 to 2019 were analyzed through molecular analysis using different PCR assays and pulse field gel electrophoresis (PFGE) analysis. The spread map (month, year and place) was constructed to locate the dissemination of altered El Tor variants of V. cholerae O1 in this region. A total of 13 cholera outbreaks were caused by V. cholerae O1 Ogawa biotype El Tor carrying ctxB1 and ctxB7 genotypes. The ctxB1 alleles of V. cholerae O1 mostly confined to the coastal areas, whereas the ctxB7 genotypes, though originating in the coastal region of Odisha, concentrated more in the tribal areas. The positive correlation between virulence-associated genes (VAGs) was found through Pearson’s correlation model, indicative of a stronger association between the VAGs. The clonal relationship through PFGE between ctxB1 and ctxB7 genotypes of V. cholerae O1 strains exhibited 80% similarity indicating single- or multi-clonal evolution. It is evident from this study that the spread of multidrug-resistant V. cholerae O1-altered El Tor was dominant over the prototype El Tor strains in this region. The origin of altered El Tor variants of V. cholerae O1 occurred in the East Coast of Odisha established that the origin of cholera happened in the Gangetic belts of Bay of Bengal where all new variants of V. cholerae O1 might have originated from the Asian countries.

Impact of the electromagnetic field pressure on the bending of high convex-side

A large number of aircraft parts made of sheet materials are used as flanges, common to such parts is the presence of walls, sides, and various elements that increase rigidity and reduce mass. These sheet parts are complex, mostly closed forms, which by plastic deformation methods require a rather complex stamping tools. Technological methods of manufacturing have certain disadvantages associated with the need to refine the shaping. In addition, the frequent updating of product designs and their constant improvement with a significant amount of experimental and small-scale production required the creation of technological methods that provide a significant reduction in terms of preparation. When punching sheet metal parts, in particular, by the pressure of magnetic-pulse field, the accuracy of shaping is mainly influenced by the shape of the flange in the process of deformation. At the final stage of shaping, an impact contact occurs between the flange of the part with the die or form-block. On impact, elastic unloading of the flange occurs due to the removal of inertial tensile stresses along the generatrix. After the impact contact, dynamic springing or rebound of the flange occurs.

Pulse Duration Dependent Asymmetry in Molecular Transmembrane Transport Due to Electroporation in H9c2 Rat Cardiac Myoblast Cells In Vitro

Electroporation (EP) is one of the successful physical methods for intracellular drug delivery, which temporarily permeabilizes plasma membrane by exposing cells to electric pulses. Orientation of cells in electric field is important for electroporation and, consequently, for transport of molecules through permeabilized plasma membrane. Uptake of molecules after electroporation are the greatest at poles of cells facing electrodes and is often asymmetrical. However, asymmetry reported was inconsistent and inconclusive—in different reports it was either preferentially anodal or cathodal. We investigated the asymmetry of polar uptake of calcium ions after electroporation with electric pulses of different durations, as the orientation of elongated cells affects electroporation to a different extent when using electric pulses of different durations in the range of 100 ns to 100 µs. The results show that with 1, 10, and 100 µs pulses, the uptake of calcium ions is greater at the pole closer to the cathode than at the pole closer to the anode. With shorter 100 ns pulses, the asymmetry is not observed. A different extent of electroporation at different parts of elongated cells, such as muscle or cardiac cells, may have an impact on electroporation-based treatments such as drug delivery, pulse-field ablation, and gene electrotransfection.

An outbreak investigation of Burkholderia cepacia infections related with contaminated chlorhexidine mouthwash solution in a tertiary care center in Turkey

Background We report a nosocomial outbreak caused by Burkholderia cepacia that occurred among six patients admitted in the medical and surgical intensive care unit between 04 March 2019 and 02 April 2019 in Istanbul, Turkey. Methods The outbreak investigation was launched on 11 March 2019 five days after the detection of B. cepacia in four different patients. We defined potential reservoirs and started environmental screening. We sampled the liquid solutions used in patient care activities. Pulse-field gel electrophoresis (PFGE) was performed to determine the genetic relatedness of environmental and patient samples. Results Burkholderia cepacia was isolated in tracheal aspiration cultures of six patients. Three out of six patients developed healthcare-associated pneumoniae due to B. cepacia. Environmental cultures in the ICUs revealed B. cepacia growth in 2% chlorhexidine-gluconate mouthwash solution that been used in the colonized patients as well as in samples obtained from the unused products. PFGE revealed the patient and a specific batch of chlorhexidine mouthwash solution samples had a 96% similarity. Conclusion Contamination of medical solutions used in critical patient care could cause outbreaks and should be detected early by infection control teams. Graphic abstract

Acute change in parasympathetic cardiac innervation after pulmonary vein isolation by pulse-field and radiofrequency energy

Background In patients with atrial fibrillation (AF), pulmonary vein isolation (PVI) by radiofrequency (RF) energy is associated with a significant change of cardiac autonomic regulations due to collateral ganglionic plexi ablation. Pulse-field (PF) ablation energy presumably spares neural tissue. Purpose We compared the effect of PVI by PF and RF energy on cardiac autonomic function. Methods A study enrolled 23 patients who underwent PVI in general anaesthesia. In 12 patients, a novel lattice-tip catheter and PF energy were used for ablation while 11 patients were ablated using a conventional irrigated-tip catheter and RF energy. The response of the sinus node (SAN) and atrioventricular node (AVN) to extracardiac high-frequency vagal stimulation (ECVS) was tested before and after PVI (via right internal jugular vein; stimulation frequency of 50 Hz; pulse width of 0.05 ms; output of 1 V/kg (<70V); train duration of 5 s). Results At baseline, physiological massive response to ECVS (sinus arrest and/or AV block) was demonstrated in the majority of patients. After PVI, complete loss of autonomic response of the SAN in 11/11 (100%) and 3/12 (25%) patients (p=0.003), and the AVN in 9/11 (82%) and 3/12 (25%) patients (p=0.01) was observed in RF and PF groups, respectively. The figure shows the maximum duration of the pause in sinus rhythm (maximum P-P interval) and AVN block (maximum R-R interval during atrial pacing) induced by ECVS after PVI. Conclusion Cardiac vagal response is preserved in a considerable proportion of AF patients after PF ablation which is in contrast with a significantly stronger effect of RF energy. This may influence the clinical outcome of AF ablation procedures. FUNDunding Acknowledgement Type of funding sources: Public Institution(s). Main funding source(s): Institute for Clinical and Experimental Medicine, Prague