Conventional Type Research Articles

Comparative study of the saddle chair with two other conventional types of chair on the risk of musculoskeletal disorders and perceived comfort in dentists

Introduction: dentists often have to adopt awkward, asymmetric, static postures and tilt their heads forward while working. If this situation continues for a long time every day, it leads to excessive pressure on the involved muscles and joints and causes symptoms such as pain and discomfort, especially in the neck, shoulders, back, and waist. Considering the importance of prevention, and early treatment of musculoskeletal disorders among dentists, this research investigates the effect of three types of chairs used in dentistry on the risk of musculoskeletal disorders and the comfort perceived by dentists using each chair.
 Materials and Methods: This is a descriptive cross-sectional study conveyed in Tehran, the capital city of Iran. The present study includes a survey of a group of 70 male dentists. In this study, three types of chairs were compared. To evaluate body comfort, Corlette, and Bishop’s local discomfort questionnaire was used. The RULA method was used to determine the risk of upper limb musculoskeletal disorders and to assess each dentist's body condition.
 Results: The highest level of comfort was reported in the saddle model chair (the difference in the average intensity of discomfort before and after the work shift in the whole body = 12.39), the third type chair (13.04), and the second type chair (18/76). The dentists' posture evaluation results showed that the final score of RULA in three types of chairs varies from a minimum of 3 to a maximum of 7.
 Conclusion: According to the results of the study, the average intensity of discomfort in the whole body after using the saddle chair compared to the state before using it has significantly decreased compared to the other two types of chairs, which implies the positive effect of using the saddle chair in reducing musculoskeletal discomfort. The results of posture evaluation indicate that the use of the saddle chair, compared to the other two chairs, improves the working conditions and facilitates the work.

A Nomogram for Enhancing the Diagnostic Effectiveness of Solid Breast BI-RADS 3-5 Masses to Determine Malignancy Based on Imaging Aspects of Conventional Ultrasonography and Contrast-Enhanced Ultrasound

BackgroundTo establish and validate a nomogram model, which can incorporate clinical data, and imaging features of ultrasound (US) and contrast-enhanced ultrasound (CEUS), for improving the diagnostic efficiency of solid breast lesions. Patients and MethodsA total of 493 patients with solid breast lesions were randomly divided into training (n = 345) and validation (n = 148) cohorts with a ratio of 7:3 and, clinical data and image features of US and CEUS were reviewed and retrospectively analyzed. The breast lesions in both the training and validation cohorts were analyzed using the BI-RADS and nomogram models. ResultsFive variables, including the shape and calcification features of conventional US, enhancement type and size after enhancement features of CEUS, and BI-RADS, were selected to construct the nomogram model. As compared to the BI-RADS model, the nomogram model demonstrated satisfactory discriminative function (area under the receiver operating characteristic [ROC] curves [AUC], 0.940; 95% confidence interval [CI], 0.909 to 0.971; sensitivity, 0.905; and specificity, 0.902 in the training cohort and AUC, 0.968; 95% CI, 0.941 to 0.995; sensitivity, 0.971; and specificity, 0.867 in the validation cohort). In addition, the nomogram model showed good consistency and clinical potential according to the calibration curve and DCA. ConclusionThe nomogram model could identify benign from malignant breast lesions with good performance.

Management of <i>Garbhashayhat vata</i> (Atrophic uterus) Through Ayurveda - A Case Report

Infertility is a burning problem all over the globe. Many couples yearn to have babies in their life. Infertility is very common issue faced by many couples from years. They use conventional type of therapy for many years and then approach Ayurveda. Vandhyatva is term used in Ayurveda for sterility. This sterility comes due to many factors occurring inside and outside of the body. Rutu, Kshetra, Ambu and Beej are the Garbhautpadkar bhava (factors important for fertilization and implantation) which are immensely important for normal fertilization and attachment of the foetus in the womb. Disorder in any of the above factor can cause infertility. Kshetra means the site where the foetus will reside. It should be normal and healthy for its survival. Derangement or pathology in it may cause failure to conceive. There are various problems which causes pathology in uterus such as endometriosis, adenomyosis, fibrosis and atrophy are a few of them. In this case report, we have a 32 years old female patient with small uterus and an irregular menstruation. The cause for her infertility was long term use of hormonal therapy for contraception purpose. She was advised to do Panchkarma for eight days and herbomineral formulations were prescribed to her for five months. After 3 months, she got her regular menses. USG pelvis before and after treatment were advised to her and positive results were obtained with Ayurvedic treatment.

Modeling Permeability Using Advanced White-Box Machine Learning Technique: Application to a Heterogeneous Carbonate Reservoir.

From exploration to production, the permeability of reservoir rocks is essential for various stages of all types of hydrocarbon field development. In the absence of costly reservoir rock samples, having a reliable correlation to predict rock permeability in the zone(s) of interest is crucial. To predict permeability conventionally, petrophysical rock typing is done. This method divides the reservoir into zones of similar petrophysical properties, and the permeability correlation for each zone is independently developed. The challenge of this approach is that the success depends upon the reservoir's complexity and heterogeneity and the methods and parameters used for rock typing. As a result, in the case of heterogeneous reservoirs, conventional rock typing methods and indices fail to predict the permeability accurately. The target area is a heterogeneous carbonate reservoir in southwestern Iran with a permeability range of 0.1-127.0 md. In this work, two approaches were used. First, based on permeability, porosity, the radius of pore throats at mercury saturation of 35% (r35), and connate water saturation (Swc) as inputs of K-nearest neighbors, the reservoir was classified into two petrophysical zones, and then, permeability for each zone was estimated. Due to the heterogeneous nature of the formation, the predicted permeability results needed to be more accurate. In the second part, we applied novel machine learning algorithms, modified group modeling data handling (GMDH), and genetic programming (GP) to develop one universal permeability equation for the whole reservoir of interest as a function of porosity, the radius of pore throats at mercury saturation of 35% (r35), and connate water saturation (Swc). The novelty of the current approach is that despite being universal, the models developed using GP and GMDH performed substantially better than zone-specific permeability, index-based empirical, or data-driven models used in the literature, such as FZI and Winland. The predicted permeability using GMDH and GP resulted in accurate prediction with R2 of 0.99 and 0.95, respectively, in the heterogeneous reservoir of interest. Moreover, as this study aimed to develop an explainable model, different parameter importance analyses were also applied to the developed permeability models, and r35 was found to be the most impactful feature.

Internal carburization and scale formation on austenitic steels in supercritical carbon dioxide

ABSTRACT Direct-fired supercritical CO2 (sCO2) power cycles are being commercialised to revolutionise fossil energy as a low-emission power source. To lower the cost of this technology, less expensive steels are needed in the lower temperature segments of the cycle. However, there are concerns about internal carburisation of steels in sCO2. 1 A consistent observation is that thin, Cr-rich oxides appear to reduce C ingress compared to thick Fe-rich oxides formed on 9–12% Cr ferritic-martensitic steels. Advanced austenitic stainless steels (SS) like alloy 709 (20Cr-25Ni) are able to continue to form Cr-rich oxides at 650°C, while a conventional type 316 H SS formed a Fe-rich scale. The C diffusion profiles in SS specimens were quantified at 550°C–650°C using glow discharge optical emission spectroscopy and electron probe microanalysis. Analytical transmission electron microscopy was used to compare the thin protective Cr-rich oxide formed on alloy 709 in sCO2 at 650°C to that formed in ambient air.

Biodegradable polymers boost reproduction in the earthworm Eisenia fetida

Microplastic contamination in soil has become a global environmental threat as it adversely affects terrestrial organisms like earthworms as well as soil properties. Especially biodegradable polymers have recently been used as an alternative to conventional polymer types, although their impact remains poorly understood. Thus, we studied the effect of conventional (polystyrene: PS, polyethylene terephthalate: PET, polypropylene: PP) versus aliphatic polyesters classified as biodegradable polymers (poly-(l-lactide): PLLA, polycaprolactone: PCL) on the earthworm Eisenia fetida and soil properties (pH and cation exchange capacity). We addressed direct effects on the weight gain and reproductive success of E. fetida, and indirect effects, like changes in the gut microbial composition as well as the production of short-chain fatty acids by the gut microbiota. Earthworms were exposed for eight weeks in an artificial soil amended with two environmentally relevant concentrations (1 % and 2.5 % (w/w)) of the different microplastic types. PLLA and PCL boosted the number of cocoons produced by 135 % and 54 %, respectively. Additionally, exposure to these two polymers increased number of hatched juveniles, changed gut microbial beta-diversity, and increased the production of the short chain fatty acid lactate compared to the control treatments. Interestingly, we also found a positive effect of PP on the earthworm's bodyweight and reproductive success. The interaction of microplastic and earthworms decreased soil pH by about 1.5 units in the presence of PLLA and PCL. No polymer effect on the cation exchange capacity of soil was found. In general, neither the presence of conventional nor biodegradable polymers had any adverse effects on any of the studied endpoints. Our results suggest that the effects of microplastic highly depend on the polymer type, and that the degradation of biodegradable polymers might be enhanced in the gut of earthworms, which implies that they may use biodegradable polymers as a potential carbon source.

Nuanced role for dendritic cell intrinsic IRE1 RNase in the regulation of antitumor adaptive immunity.

In cancer, activation of the IRE1/XBP1s axis of the unfolded protein response (UPR) promotes immunosuppression and tumor growth, by acting in cancer cells and tumor infiltrating immune cells. However, the role of IRE1/XBP1s in dendritic cells (DCs) in tumors, particularly in conventional type 1 DCs (cDC1s) which are cellular targets in immunotherapy, has not been fully elucidated. Here, we studied the role of IRE1/XBP1s in subcutaneous B16/B78 melanoma and MC38 tumors by generating loss-of-function models of IRE1 and/or XBP1s in DCs or in cDC1s. Data show that concomitant deletion of the RNase domain of IRE1 and XBP1s in DCs and cDC1s does not influence the kinetics of B16/B78 and MC38 tumor growth or the effector profile of tumor infiltrating T cells. A modest effect is observed in mice bearing single deletion of XBP1s in DCs, which showed slight acceleration of melanoma tumor growth and dysfunctional T cell responses, however, this effect was not recapitulated in animals lacking XBP1 only in cDC1s. Thus, evidence presented here argues against a general pro-tumorigenic role of the IRE1/XBP1s pathway in tumor associated DC subsets.

A Study on Coldflame Propagation Characteristics Applying Amplified Ignition Source to Overcome Landfill gas’s Flame Retardant Limit

In this study combustion characteristics were analyzed with LFG, one of the alternative energy sources of SI engines. To overcome the flame retardant limit, which is the shortcoming of LFG, the combustion characteristics were analyzed using the AIS device that was created for this study’s purpose. A static combustion chamber to which AIS can be applied was designed for the experiment that was conducted on the coldflame propagation and combustion characteristics of each LFG fuel using C-type (conventional ignition type) and AIS devices. From the basic LFG experiment, it was identified that as the proportion of carbon dioxide in the fuel increased, the combustibility decreased, and the combustion pressure decreased. When using the AIS device to overcome the flame retardancy of LFG, the combustion pressure was increased by 2 bar even in LFG70 and LFG60, where combustion was actively occurring with the C-type and the combustibility was improved in LFG50 as well. In overall respects, it was judged that the use of AIS could overcome the flame retardancy of LFG and could incorporate LFG into SI engines.

Effect of the Volumetric Flow Rate Measurement Methodology of Positive Pressure Ventilators on the Parameters of the Drive Unit

The nature and conditions of the execution of tests (open or duct flow) in terms of evaluating the flow rate generated by positive pressure ventilators (PPV) may affect the parameters of the drive unit recorded during testing. In this article, popular PPVs (conventional type—W1 and turbo type—W2) of about 4.2 kW were tested under open flow (Method A) and duct flow (Method B) conditions. During the tests, engine load values were recorded: torque, speed, horsepower and, using portable emissions measurement systems (PEMS), exhaust gas emissions: carbon monoxide (CO), carbon dioxide (CO2), hydrocarbons (HC), nitrogen oxides (NOx) and fuel consumption. Depending on the method used to measure ventilator flow rates, drive units can have different drive power requirements (from 3.2% to 4.5%). Changes in drive unit operating conditions induced by the flow measurement method are observed in the results of fuel consumption (from 0.65% to 9.8%) and emissions of harmful exhaust compounds: CO2 up to 2.4%, CO up to 67%, HC up to 93.2% and NOx up to 37%. The drive units of turbo type fans (W2) are more susceptible to the influence of the test methods in terms of flow assessment, where they have higher emissions of harmful exhaust gases when tested by Method A. Flow measurement methods affect the oscillation of propulsion power, which contributes to disturbances in the control of the fuel–air mixture composition. The purpose of this article is to analyse the impact of testing methods for measuring the flow rate of positive pressure ventilators on the performance of the drive unit.

Performance Analysis of Electric Locomotive using Matrix Converter

The conventional type electric locomotive consists of traction transformer, traction converter and three phase induction motor. The conventional type traction converter contains rectifier and inverter which makes it huge, less efficient and difficult to maintain. In this research, the conventional traction converter is replaced by a single matrix converter (AC to AC converter) with bidirectional switches. The proposed converter is analyzed using different Pulse Width Modulation techniques namely sinusoidal pulse width modulation, and space vector pulse width modulation, and the performance of proposed converter is observed by using MATLAB.

Superconductivity in type II layered Weyl semi-metals

Novel ‘quasi 2D’ typically layered (semi)metals offer a unique opportunity to control the density and even the topology of electronic matter. In intercalated MoTe 2 type II Weyl semi-metal the tilt of the dispersion relation cones is so large that topologically the Fermi surface is distinct from a more conventional type I. Superconductivity observed recently in this compound (Zhang et al 2022 2D Mater. 9 045027) demonstrated two puzzling phenomena. The gate voltage has no impact on critical temperature, in a wide range of density, while it is very sensitive to the inter-layer distance. A phonon theory of pairing in a layered Weyl material including the effects of Coulomb repulsion is constructed, which explains the above two features in MoTe 2. The first feature turns out to be a general one for any type II topological material, while the second reflects properties of the intercalated materials affecting the Coulomb screening.

Experimental study on interlayer interference effect of CBM commingled production in a multi-pressure system under output control mode

This research adopted the self-developed test device to conduct tests to understand the interlayer interference in a multi-pressure system under output control mode. It analyzed the reservoir response and gas production characteristics in coalbed methane (CBM)'s commingled production and discussed the interlayer interference mechanism. The results revealed that the CBM's commingled production at the initial stage would generate interlayer interference under the output control mode, causing the cross-fluids of interlayer fluids. The interlayer interference would form a gas-production state. That is, the gas production of reservoirs with high fluid energy would inhibit that of the reservoirs with low fluid energy. When the gas production of reservoirs with high fluid energy is attenuated, that of reservoirs with low fluid energy would start recovering to maintain stable production. The reservoir pressure gradients positively influence interlayer interference. The more significant the difference between the reservoir's fluid energies aggravates, the more severe this interlayer interference. The output control values negatively affect the interlayer interference, as their increase would weaken the severity of interlayer interference. Therefore, the output control design should appropriately increase the output value or rationally select the reservoirs with a slighter difference in fluid energies. The gas model can be divided into three: conventional type, inhibitory type, and reverse-flow type, and their production stage can be divided into five different phases: gas rise, gas inhibition, reverse flow, gas recovery, and gas attenuation.

Single-Site Carbon-Supported Metal-Oxo Complexes in Heterogeneous Catalysis: Structure, Reactivity, and Mechanism.

When early transition metal complexes are molecularly grafted onto catalyst supports, well-defined, surface-bound species are created, which are highly active and selective single-site heterogeneous catalysts (SSHCs) for diverse chemical transformations. In this minireview, we analyze and summarize a less conventional type of SSHC in which molybdenum dioxo species are grafted onto unusual carbon-unsaturated scaffolds, such as activated carbon, reduced graphene oxide, and carbon nanohorns. The choice of earth-abundant, low-toxicity, versatile metal constituents, and various carbon supports illustrates "catalyst by design" principles and yields insights into new catalytic systems of both academic and technological interest. Here, we summarize experimental and computational investigations of the bonding, electronic structure, reaction scope, and mechanistic pathways of these unusual catalysts.

Single‐Site Carbon‐Supported Metal‐Oxo Complexes in Heterogeneous Catalysis: Structure, Reactivity, and Mechanism

AbstractWhen early transition metal complexes are molecularly grafted onto catalyst supports, well‐defined, surface‐bound species are created, which are highly active and selective single‐site heterogeneous catalysts (SSHCs) for diverse chemical transformations. In this minireview, we analyze and summarize a less conventional type of SSHC in which molybdenum dioxo species are grafted onto unusual carbon‐unsaturated scaffolds, such as activated carbon, reduced graphene oxide, and carbon nanohorns. The choice of earth‐abundant, low‐toxicity, versatile metal constituents, and various carbon supports illustrates “catalyst by design” principles and yields insights into new catalytic systems of both academic and technological interest. Here, we summarize experimental and computational investigations of the bonding, electronic structure, reaction scope, and mechanistic pathways of these unusual catalysts.

Flow structure and performance analysis of Darrieus vertical axis turbines with swept blades: A critical case study on V-shaped blades

Blade geometric modification is one favorite way of enhancing the performance of vertical axis turbines. In this regard, V-shaped blades are a novel design featuring some leading-edge sweep angle. Currently, the relevant literature only focuses on finding the optimum parameters of the V-shaped blades and lacks a deep understanding of how they alter flow structure and whether they offer any performance improvement compared to other conventional types. To this aim, using three-dimensional numerical simulations, the flow structure and performance of two different V-shaped blade turbines, twisted and untwisted, are compared with straight and helical-blade turbines at tip speed ratios (TSRs) ranging from 0.69 to 1.5. Turbine torque average and fluctuation amplitude are chosen as the performance metrics. It is shown that the sweeping configuration of the V-shaped and helical types causes an inevitable spanwise flow, resulting in a performance loss, which makes neither type of V-shaped blade turbine advantageous at low TSRs.

Cataract Surgery-Indications, Techniques, and Intraocular Lens Selection.

Opacification of the lens of the eye (cataract) is usually due to aging. It is a painless, progressive condition that affects contrast and color perception and alters refraction, leading to visual loss that may be total. In cataract surgery, the turbid lens is replaced by an artificial lens. An estimated 600 000 to 800 000 such procedures are performed in Germany each year. This review is based on pertinent publications retrieved by a selective search in PubMed, including meta-analyses, Cochrane reviews, and randomized controlled clinical trials (RCTs). Cataract is the most common reversible cause of blindness around the world (approximately 95 million people). The surgical replacement of a turbid lens with an artificial lens is usually carried out under local anesthesia. The standard technique for fragmentation of the nucleus of the lens is ultrasonic phacoemulsification. RCTs have not shown the superiority of the femtosecond laser over phacoemulsification for this purpose so far. The spectrum of artificial intraocular lenses, aside from the conventional type with a single focus, include lenses with multiple foci, extended-depth-of-focus (EDOF) lenses, and astigmatism-correcting lenses. In Germany, cataract surgery is usually performed on an outpatient basis under local anesthesia. Artificial lenses with various additional functions are available nowadays; the choice of lens depends on the needs of the individual patient. Patients must be adequately informed about the advantages and disadvantages of the different lens systems.

Discovery of highly immunogenic spleen-resident FCGR3+CD103+ cDC1s differentiated by IL-33-primed ST2+ basophils

Recombinant interleukin-33 (IL-33) inhibits tumor growth, but the detailed immunological mechanism is still unknown. IL-33-mediated tumor suppression did not occur in Batf3−/− mice, indicating that conventional type 1 dendritic cells (cDC1s) play a key role in IL-33-mediated antitumor immunity. A population of CD103+ cDC1s, which were barely detectable in the spleens of normal mice, increased significantly in the spleens of IL-33-treated mice. The newly emerged splenic CD103+ cDC1s were distinct from conventional splenic cDC1s based on their spleen residency, robust effector T-cell priming ability, and surface expression of FCGR3. DCs and DC precursors did not express Suppressor of Tumorigenicity 2 (ST2). However, recombinant IL-33 induced spleen-resident FCGR3+CD103+ cDC1s, which were found to be differentiated from DC precursors by bystander ST2+ immune cells. Through immune cell fractionation and depletion assays, we found that IL-33-primed ST2+ basophils play a crucial role in the development of FCGR3+CD103+ cDC1s by secreting IL-33-driven extrinsic factors. Recombinant GM-CSF also induced the population of CD103+ cDC1s, but the population neither expressed FCGR3 nor induced any discernable antitumor immunity. The population of FCGR3+CD103+ cDC1s was also generated in vitro culture of Flt3L-mediated bone marrow-derived DCs (FL-BMDCs) when IL-33 was added in a pre-DC stage of culture. FL-BMDCs generated in the presence of IL-33 (FL-33-DCs) offered more potent tumor immunotherapy than control Flt3L-BMDCs (FL-DCs). Human monocyte-derived DCs were also more immunogenic when exposed to IL-33-induced factors. Our findings suggest that recombinant IL-33 or an IL-33-mediated DC vaccine could be an attractive protocol for better tumor immunotherapy.

A human model of asthma exacerbation reveals transcriptional programs and cell circuits specific to allergic asthma.

Asthma is a chronic disease most commonly associated with allergy and type 2 inflammation. However, the mechanisms that link airway inflammation to the structural changes that define asthma are incompletely understood. Using a human model of allergen-induced asthma exacerbation, we compared the lower airway mucosa in allergic asthmatics and allergic non-asthmatic controls using single-cell RNA sequencing. In response to allergen, the asthmatic airway epithelium was highly dynamic and up-regulated genes involved in matrix degradation, mucus metaplasia, and glycolysis while failing to induce injury-repair and antioxidant pathways observed in controls. IL9-expressing pathogenic TH2 cells were specific to asthmatic airways and were only observed after allergen challenge. Additionally, conventional type 2 dendritic cells (DC2 that express CD1C) and CCR2-expressing monocyte-derived cells (MCs) were uniquely enriched in asthmatics after allergen, with up-regulation of genes that sustain type 2 inflammation and promote pathologic airway remodeling. In contrast, allergic controls were enriched for macrophage-like MCs that up-regulated tissue repair programs after allergen challenge, suggesting that these populations may protect against asthmatic airway remodeling. Cellular interaction analyses revealed a TH2-mononuclear phagocyte-basal cell interactome unique to asthmatics. These pathogenic cellular circuits were characterized by type 2 programming of immune and structural cells and additional pathways that may sustain and amplify type 2 signals, including TNF family signaling, altered cellular metabolism, failure to engage antioxidant responses, and loss of growth factor signaling. Our findings therefore suggest that pathogenic effector circuits and the absence of proresolution programs drive structural airway disease in response to type 2 inflammation.

Satisfaction with labial reinforcement of custom-made mouthguards among a cohort of rugby union players: A randomized crossover trial.

The optimal mouthguard design for athletes remains unclear. This study assessed satisfaction and preference among rugby union players for custom mouthguards with and without labial reinforcement. It also assessed discomfort and perceived protection. This prospective randomized controlled trial used a crossover design of four 1-week periods to compare conventional (Type A) and labial reinforced (Type B) customized 2 mouthguards for rugby union players from February to May 2022. Type B mouthguards included a 0.75-mm insert of polyethylene terephthalate glycol (Duran) in the anterior labial region. We ensured intraoral occlusion accommodation for both mouthguards. Players wore each mouthguard type when training and in competitive matches for 2 weeks according to one of two randomized sequences, and after each session, they rated the mouthguard on 10-point scales regarding discomfort, functional interference, protection, and general satisfaction. After 4 weeks, we asked participants to nominate their preferred mouthguard. In total, 22 of the 24 invited players (16 men and 6 women) were included. We observed no significant differences in discomfort, functional interference, protection, or general satisfaction by mouthguard type (P > .05 Wilcoxon test). Ultimately, 12 players (55%) preferred the Type A mouthguard and 10 (45%) preferred the Type B mouthguard (P = .832; one-sample binomial test). No serious adverse events occurred. Labial reinforcement does not affect satisfaction, perceived comfort and protection, or mouthguard preference among rugby union players. Int J Prosthodont 2023. doi: 10.11607/ijp.8444 Trial registration: NCT05238480 (ClinicalTrials.gov).

Two step I to II type transitions in layered Weyl semi-metals and their impact on superconductivity

Novel “quasi two dimensional” typically layered (semi) metals offer a unique opportunity to control the density and even the topology of the electronic matter. Along with doping and gate voltage, a robust tuning is achieved by application of the hydrostatic pressure. In Weyl semi-metals the tilt of the dispersion relation cones, kappa , increases with pressure, so that one is able to reach type II (kappa >1starting from the more conventional type I Weyl semi-metals kappa <1. The microscopic theory of such a transition is constructed. It is found that upon increasing pressure the I to II transition occurs in two continuous steps. In the first step the cones of opposite chirality coalesce so that the chiral symmetry is restored, while the second transition to the Fermi surface extending throughout the Brillouin zone occurs at higher pressures. Flattening of the band leads to profound changes in Coulomb screening. Superconductivity observed recently in wide range of pressure and chemical composition in Weyl semi-metals of both types. The phonon theory of pairing including the Coulomb repulsion for a layered material is constructed and applied to recent extensive experiments on HfTe_{5}.