Rod System Research Articles

Establishing rod shape from spherical, peptidoglycan-deficient bacterial spores

Chemical-induced spores of the Gram-negative bacterium Myxococcus xanthus are peptidoglycan (PG)-deficient. It is unclear how these spherical spores germinate into rod-shaped, walled cells without preexisting PG templates. We found that germinating spores first synthesize PG randomly on spherical surfaces. MglB, a GTPase-activating protein, forms a cluster that responds to the status of PG growth and stabilizes at one future cell pole. Following MglB, the Ras family GTPase MglA localizes to the second pole. MglA directs molecular motors to transport the bacterial actin homolog MreB and the Rod PG synthesis complexes away from poles. The Rod system establishes rod shape de novo by elongating PG at nonpolar regions. Thus, similar to eukaryotic cells, the interactions between GTPase, cytoskeletons, and molecular motors initiate spontaneous polarization in bacteria.

A dynamic thermo-mechanical actuator system with contact and Barber's heat exchange boundary conditions

AbstractThis work, motivated by the rapid developments in Micro-Electro-Mechanical Systems (MEMS) structures, especially actuators and grippers, analyses the dynamics of a thermo-mechanical system consisting of a horizontal beam joined at one end to a vertical rod. As a result of thermal expansion or vibration of the rod, the other end may come into contact with another part of the MEMS device and that closes an electrical circuit, which is the actuating or switching function of such a beam–rod system. The interaction between the rod's contacting end and the supporting device is described by a normal compliance contact law for the displacements and by an inclusion-type Barber's heat exchange condition for the temperature. The heat-exchange coefficient is a multi-function taking into account the air resistance in the gap when there is no contact and the contact pressure when contact occurs. The model consists of a nonlinear variational inclusion for the temperature coupled with a nonlinear variational equation for the displacements. The existence of a weak solution to the problem is proved by using the Galerkin method, a regularization of Barber's condition with the Yosida approximation of a maximal monotone operator, and a priori estimates.

Treatment of spine metastases by open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system

To evaluate the preliminary clinical effective of open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system in the treatment of spine metastases. The clinical data of 12 patients with spine metastases were retrospectively analyzed, they were treated with open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system between January 2014 and January 2016. Six males and 6 females were included, aged from 30 to 75 years old with an average of 55.6 years. There were 5 cases with spine metastases from lung cancer, 2 from breast cancer, 2 from thyroid cancer, 2 from renal cancer and 1 from liver cancer. Sevencases were thoracic metastases and 5 cases were lumbar metastases. Tomita score were mainly arranging from 3 to 6 points. According to ASIA neurologic grading system, 3 patients were grade C, 1 was grade D, 8 were grade E. Preoperative VAS score was 8.3±0.4. VAS was used to evaluate the clinical effect at 1, 3, 6 months after operation and final follow-up. All operations were successful and the amount of blood loss during surgery was 500 to 2 050 ml (average of 850 ml), operation time was 3.5 to 5.5 h (average of 4.5 h). There was no nerve root injury during surgery. Cerebrospinal fluid leakage occurred in 3 cases after surgery, which were healed after conservative treatment. Superficial infection of the incision occurred in 2 cases, which were healed after dressing change. There was one case of pulmonary infection. No deep infection, lower limb thrombosis or other complications were found. All 12 patients were followed up for 9 -40 months with an average of 28.6 months. The clinical symptoms of all patients were significantly improved, and the motor function of the lower limbs was recovered to varying degrees. According to ASIA grade, 2 cases of grade C were improved to grade B;1 case of grade C did not recover significantly;1 case of grade D was improved to grade E. One patient died of primary liver cancer 10 months after surgery. Local tumor recurrence occurred in 1 patient during follow up period. The VAS scores were 2.7±0.6, 2.5±0.4, 2.6±0.5, and 2.5±0.5 at 1, 3, 6 months after surgery and at final follow-up, which were significantly improved compared with the score before surgery(P<0.05). Open decompression, microwave ablation combined with open vertebroplasty and pedicle screw rod system in the treatment of spine metastases show some effects, with less intraoperative blood loss, shorter operation time, significant postoperative pain relief, and low tumor recurrence rate.

The Joe-Lin Operative Classification System for Pediatric Lumbosacral Spondylolysis and Spondylolisthesis

To propose and validate a novel and comprehensive classification of lumbosacral spondylolysis and spondylolisthesis in the pediatric population according to surgical managements. Cases of pediatric lumbosacral (L5/S1 level) spondylolysis and spondylolisthesis were reviewed. Lumbar Japanese Orthopedics Association score, health-related quality of life, spondylolisthesis, lumbosacral disc degeneration, and dysplastic features were included for evaluation of outcomes after surgery. We also conducted a reliability study to assess the classification. A classification containing 4 types and a tentative treatment algorithm were proposed: type 1, direct pars repair without segmented fusion, for which thepedicle screw-U rod system is suitable; type 2, simple L5-S1 fusion; type 3, simple L4-S1 fusion; and type 4, simple L5-S2 fusion. All types of spondylolisthesis were suggested to achieve complete reduction and decompression. A total of 162 patients were included and we also reviewed the outcomes of patients in each type. All patients achieved satisfied outcomes. The reliability study showed that the average interobserver agreement was 89.5% (range, 85.2%-92.6%), with κ value of 0.862 (range, 0.802-0.901). Intraobserver agreement ranged from 88.9% to 92.6%, with an average κ value of 0.868 (range, 0.835-0.901). In our study, we proposed and validated a novel comprehensive classification of pediatric lumbosacral spondylolysis and spondylolisthesis. The pedicle screw-U rod system provided more benefits in the treatment of simple lumbosacral spondylolysis, and fusion from L5 to S2 combined with S2 screw would also benefit patients with high-degree spondylolisthesis.

Tensile buckling of repetitive rods systems with overlapping

In structural engineering, buckling is usually associated with compressive stress and/or shortening deformation states. Recently, several works came to light alerting to the propensity of some structural systems to buckle under tension. Within this context, the present work examines the buckling and post-buckling behaviours of repetitive rods systems under tensile axial loading, and comprises three distinct parts. At first, the tensile stability behaviour of a single rigid rod with an edge section supported by a slider that is forced to follow a pre-established path, developed in the literature that lays behind us, is revisited and related to the buckling behaviour of an alternative two rods system whose buckling propensity arises from a secondary compressed bar overlapping the tensioned one. In the second part of the paper, overlapping is used to create innovative repetitive frames that buckle under tension, in the present case a sequence of lined up rigid rods connected by rotational joints. The tensile critical load shows little change as new modules are added to the system, in clear contrast with the compressive case. The tensile post-buckling behaviour is also assessed, in some cases showing original shapes, and overlapping is used to create repetitive frames with negative thermal expansion coefficient as well. In the third part of the paper, the effects of applying global gradients to the relevant mechanical properties, in the form of smooth variations of the joints rigidities and rods lengths as the module is repeated, on the stability behaviour under tension are assessed. Although these variations are smooth and kept within small values, they provoke significant changes on the tensile buckling load, on the buckling type and on the type of buckling as well. The findings pave the way to the development of innovative repetitive frames, cellular materials, polymer chains and origami structures showing original constitutive behaviours under tension.

Методика расчета на прочность волноводов для обеспечения улучшенных массогабаритных параметров

This paper presents a calculation procedure for designing waveguides with iproved mass-dimensional parameters, which ensures the required strength and stiffness characteristics under static, dynamic and deformational loads. The procedure is based on the analysis of methods for determining the stress-strain state of the waveguide-and-distribution systems of spacecraft. The first stage of the procedure involves modelling the waveguide-and-distribution systems in a general formulation by a rod structure with equivalent loading and fixing conditions and determining the stress-strain state of such a system. At the second stage, local areas with the maximum stress-strain state values are selected for a further refined analysis in the rod system. An evaluation of the influence of the waveguide wall thickness on the general stress-strain state is performed. It is shown that when the waveguide wall thickness varies in the range of 0.25 – 2.50 mm, the strength and stiffness of its sections under static loads basically follow the linear law. It is established that under dynamic loading the wall thickness has almost no effect on the resultant stress-strain state of the waveguide arising under the influence of forced fluctuations and quasi-static loading owing to its dependence on the ratios of mass, moments of inertia and resistance, which for some standard sizes of the waveguides will be almost constant. The equations obtained for the rod system cannot be used for evaluating the influence of the wall thickness on local stress-strain state in the form of wall deflection, local loss of stability, etc. In view of this, at the second stage of modelling local areas of interest are selected and transformed into 3D thin-walled structures, with translation into finite element method programs for a more exact analysis. In the future, the proposed technique can be used to solve connected problems of interrelation and the influence of cross-sectional deformations in local zones of the waveguide on the changes in electromagnetic fields with the formation of parasite waves. This will significantly improve the quality of radio engineering characteristics of the waveguide and distribution systems while ensuring their strength, stiffness and minimal mass-dimensional parameters.

Predatory protists.

The vast majority of eukaryotic life is made up of single cells commonly referred to as protists. In this primer, Leander provides an introduction to predatory protists - cells that eat other cells. This lifestyle, in particular the use of phagocytosis, makes endosymbiosis possible and enabled the evolution of complex cells.

Laser-Induced Microgrooves Improve the Mechanical Responses of Cemented Implant Systems

The impact of a laser-induced microgroove (LIM) architecture on mechanical responses of two cemented implant systems was evaluated. One system consisted of two aluminum alloy rods bonded end-to-end by polymethylmethacrylate cement. The second system consisted of a custom-made, aluminum tibial tray (TT) cemented in an artificial canine tibia. Control specimens for each system were polished smooth at the cement interface. For LIM samples in the rod system, microgrooves were engraved (100 µm depth, 200 µm width, 500 µm spacing) on the apposing surface of one of the two rods. For TT system testing, LIM engraving (100 µm spacing) was confined to the underside and keel of the tray. Morphological analysis of processed implant surfaces revealed success in laser microgrooving procedures. For cemented rods tested under static tension, load to failure was greater for LIM samples (279.0 ± 14.9 N vs. 126.5 ± 4.5 N). Neither non-grooved nor grooved TT samples failed under cyclic compression testing (100,000 cycles at 1 Hz). Compared with control specimens, LIM TT constructs exhibited higher load to failure under static compression and higher strain at the bone interface under cyclic compression. Laser-induced microgrooving has the potential to improve the performance of cemented orthopedic implants.

A novel homozygous frameshift variant in the cellular retinaldehyde-binding protein 1 (RLBP1) gene causes retinitis punctata albescens.

Retinitis punctata albescens is a form of retinitis pigmentosa characterized by white fleck-like deposits in the fundus, in most cases caused by pathogenic variants in RLBP1 gene. The purpose of this work is to report the phenotypic and genotypic data of a patient with retinitis punctata albescens carrying a deletion in the RLBP1 gene. An 8-year-old Caucasian female has been complaining of nyctalopia for the last 2 years. No other ocular symptoms were present. No relevant past medical or familiar history was described. At clinical examination, the patient's best-corrected visual acuity was 20/20 in both eyes. Anterior segment evaluation and intraocular pressure were normal in both eyes. At fundoscopy, multiple punctate whitish-yellow fleck-like lesions were observed in the proximity of temporal superior and inferior vascular arcades. Scotopic electroretinogram demonstrated severely reduced rod response, without improvement or recovery of rod system function after prolonged dark adaptation. Blood DNA samples of this patient and from her parents were screened for causal variants in RLBP1, RDH5, and PRPH2. A probable pathogenic frameshift variant was identified in homozygosity in the RLBP1 gene with an autosomal recessive transmission as another cause of retinitis punctata albescens. This DNA variant will aid ongoing functional studies and add to our understanding of the molecular pathology about RLBP1-associated retinopathies.

DESIGN OF COMPOSITE CONCENTRATORS FOR PIEZOCERAMIC ULTRASONIC HEADS

The problems of designing composite concentrators for piezoceramic ultrasonic heads taking into account the laws of the rod system are considered.

Interaction Networks Of A Crucial Cell Wall Enzyme In The Resistant Bacterium Acinetobacter baumannii

Acinetobacter baumannii is a common hospital opportunistic pathogen with multidrug resistance, including resistance to last‐resort antibiotics. Many antibiotics today target the cell wall system which is critical for viability. Thus, we sought to better understand cell wall biogenesis in A. baumannii with the goal of finding novel therapeutic targets. L,D‐transpeptidases have been shown to participate in cell wall synthesis by forming unusual peptidoglycan crosslinks. A. baumannii has an L,D‐transpeptidase (Ldt1) that is essential for maintaining the characteristic rod‐shape of the bacterium. However, this transpeptidase and other aspects of cell wall synthesis remain poorly defined. We hypothesized that Ldt1 is important for cell elongation, which is mediated by a multiprotein complex known as the Rod system. To test this hypothesis and define genetic and direct‐protein interactions of Ldt1, we used transposon sequencing (Tn‐seq) and bacterial two‐hybrid techniques. Additionally, we used fluorescent D‐amino acid probes and fluorescence microscopy to visualize differences in active cell wall synthesis sites in WT A. baumannii versus ldt1 deletion mutant. The strongest negative Tn‐seq interactions were with cell division genes, consistent with the hypothesis that Ldt1 is important for the complementary Rod system. The results of the two‐hybrid assay did not show strong direct protein‐protein interaction of Ldt1 with canonical rod‐system components; however, using this method, we mapped novel interactions within the Rod system of A. baumannii. For the fluorescence microscopy, staining conditions of the D‐amino acid probe have been optimized. This study demonstrates methods of elucidating interaction networks in A. baumannii. Through increased understanding of Ldt1 and the Rod system interaction networks, novel synergistic therapeutics can be developed to combat resistant A. baumannii infections.

Validation results of the BIPR-8A code, the new module of the software package KASKAD

Abstract The BIPR-8A executable module is a main component of the BIPR 2007 code. This module is intended for three-dimensional coarse mesh calculation of the VVER reactor cores. This paper presents the results of validation of the BIPR-8A executable module. Validation is based on comparison of the calculated results with the operating data of power plants with the VVER-440, VVER-1000 and VVER-1200 reactors, and with the results of calculations obtained by using Monte Carlo codes. The results of comparison of the following values at HZP (hot zero power) power level and operational power level are presented: critical concentration of boric acid, temperature reactivity coefficient, efficiency of the control rods system, relative power distribution of fuel assemblies and 3D power distribution, effective multiplication factor.

Neutronic feasibility study of using a multipurpose MNSR for BNCT, NR, and NAA

In this study, the conceptual design of a multipurpose research reactor for boron neutron capture therapy (BNCT), neutron radiography (NR) and neutron activation analysis (NAA) applications has been performed. Specifically, a suitable epithermal neutron flux (φEpi) of about 1×109 (n.cm−2.s−1) for BNCT and high quality thermal neutron flux (φTh) of above 1×106 (n.cm−2.s−1)for NR are carried out based on our LEU reactor core designing. The UO2 fuel with density of 10.5 g/cm3 and enrichment of 12.4% is applied as an appropriate LEU fuel. The reactor safety is assured by designing the safety control rod system with two banks. A fission converter facility (FCF) consists of 19 fuel rods of UO2 is used to increase φEpi for BNCT treatment. Furthermore, a unique thermal column of heavy water is used to increase φTh for NR purpose. Four internal irradiation sites, two external irradiation sites, and one large thermal column irradiation site are considered at the reactor which can be used for NAA application. The results of neutronic calculations show that the reactor meets the neutronic design limits for a low power research reactor.

Novel mutations of RPGRIP1 gene in a family with Leber congenital amaurosis

Objective To identify the pathogenic gene mutations in a family with Leber congenital amaurosis (LCA). Methods In October 2018, 1 patient and 3 normal family members from a LCA family was enrolled in this retrospective study. Detailed medical history of proband was obtained and fixation test, cycloplegic refraction, slit-lamp, fundus color photography and full-field ERG were performed. And other family members underwent BCVA, refraction slit-lamp, fundus biomicroscopy with the slit lamp, fundus color photography and full-field ERG. The family was investigated with a specific hereditary eye disease enrichment panel which contained 441 known pathogenic genes and based on targeted exome capture technology first to indentify the potential pathogenic genes and mutations. Then the potential pathogenic mutations were conformed by Sanger sequencing. Finally, the results were analyzed via bioinformatics analysis. Results The proband showed no trace object from childhood, but had obvious photophobia and nystagmus. No positive changes were found in the anterior segment, vitreous and retina in both eyes. Both cone and rod system function decreased significantly in full-field ERG in both eyes. Gene tests showed the proband carried both RPGRIP1 c.1635dupA and c.3565C> T, which composited a heterozygous mutation. Bioinformatics analysis showed RPGRIP1 c.1635dupA was a pathogenic mutation, and RPGRIP1 c.3565C> T which was a novel potential pathogenic mutation in LCA. Conclusion The compound heterozygous mutation, c.1635dupA and c.3565C> T in RPGRIP1 may be responsible for the pathogenesis in this Chinese Han LCA pedigree. Key words: Leber congenital amaurosis/etiology; Genes; Mutation; RPGRIP1 gene

Research on performance enhancement of nuclear fuel with SiC cladding by using high thermal conductivity fuels

The engineering application of the fuel rod system consisting of traditional UO2 pellets and SiC accident tolerant fuel (ATF) cladding is challenged by high fuel operating temperatures, large fission gas release rates and high risks of brittle failure of the cladding. In this study, a preliminary research was carried out for performance enhancement of the fuel rods consisting of SiC cladding by replacing UO2 with high thermal conductivity fuels, including UO2/BeO, U3Si2 and UN/U3Si2. Thermo-mechanical modeling was conducted with the consideration of burnup effects for the three fuels with high thermal conductivity. An upgrade of the nuclear fuel analysis code FRAPCON4.0 was conducted to extend the simulation capability by implementing the new fuel models. Thermo-mechanical behavior of the original and improved fuel rods was simulated by the upgraded FRAPCON4.0. The simulation results show that using high thermal conductivity fuels can significantly reduce the fuel temperature and fission gas release. Furthermore, the fuel gaseous swelling is greatly mitigated due to the reduced fuel temperature, which is beneficial to prevent SiC cladding from brittle failure caused by pellet-cladding mechanical interaction. By comparison, UN/U3Si2 fuel presents the most promising and desired thermo-mechanical performance among all high thermal conductivity fuels investigated in this study.

COMPOUND RUNS OF LOGS CALCULATION: ACCOUNTING OF LONGITUDINAL FORCES’ AND BENDING MOMENTS’ INTERACTION

Introduction. Studying the designing and constructing experience of beam bridges with composite log girders indicates the possibility of the load bearing capacity rising of the structures and their further usage in the IV and V categories bridges’ construction under A-11 and H-11 loads. The purpose of the research is to evaluate the effect on the magnitude and distribution of shear forces in shear bonds, considering the permissible pliability of fixation in wood and on the nature of the stress state change in the rods of the composite girders.Materials and methods. The authors presented the construction of the composite girder in the form of three rows united by means of tie bolts and gaskets of four-tier single-row composite girders and made of edged logs. The proposed studying method of a composite girder stress-strain state with discrete placement of concentrated shear bonds in the joints based on the classical method of forces for rod systems, taking into account the interaction of longitudinal forces and bending moments arising in the rods composing the girder of unknown forces in the shear bonds.Results. The determination of single displacements with joint account of bending and stretching-compression deformations haв a significant impact on the redistribution of shear forces in the direction of increasing them in the support zones and reducing them in the middle of the span, and, consequently, on the design of the connecting elements. The character of distribution of normal stresses on the stretching-compression indicated the rods’ girders between relationships under the eccentric compression (stretching).Discussion and conclusions. The proposed solutions demonstrate the most accurate assessment of the composite girders in the structures of spans wooden bridges and present the application possibility in modern conditions.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.

Identification of Downhole Conditions in Sucker Rod Pumped Wells Using Deep Neural Networks and Genetic Algorithms (includes associated discussion)

Summary In this paper, deep learning artificial neural networks (ANNs) are used to analyze the features of downhole dynamometer cards and identify the sucker rod pumping system conditions. A description model for the dynamometer cards, using Fourier descriptors, was established for card feature extraction. Then, neural networks were trained to generate failure prediction models to recognize downhole faults of the rod pumping systems. The failure prediction models were validated and tested with a large database of previously interpreted cards. The proposed model is trained by using 4,467 dynamometer cards—29.2% of these cards represent sucker rod pumping systems of normal conditions, while the rest (70.8%) represent faulty sucker rod pumping systems. Genetic algorithms (GAs) were used to search for the best deep ANN structure that gives highest accuracy for the testing data. Accuracy of the proposed ANN model was measured with 1,915 cards that were not used in developing the ANN. The proposed model identified the sucker rod system failure successfully with very high accuracy (99.69%).

Mathematical model and simulated power performance of a novel O-type engine

Reciprocating engines such as V-type, L-type and W-type engines are used widely in our daily life. However, there is still some room for the improvement of power performance if the configuration of the cylinder and connecting rod system is changed. In this paper, a novel O-type engine is put forward firstly. The structural features of the O-type cylinder sets are described briefly, and then the relevant mathematical model with hypotheses is established to conduct the performance analysis. Secondly, the O-type engine is compared with the general range of power performance of gasoline engine to demonstrate its merits. Then, the power performance indicators, namely the mean indicated pressure (PMI), space occupation efficiency (SOE) and heat efficiency (HE) of the novel engine are analysed and discussed in detail through MATLAB with the verification and validation which are conducted to ensure the reliability of results. And the results show that the power performance of the O-type engine is better than most of gasoline engines; the power performance indicators in the research are not monotonous at different volumes with the bore stroke ratio increasing; the proper range of the volume and the bore stroke ratio is obtained to make the engine achieve a high power performance. All in all, the research is helpful for the development and application of the O-type engine.

RESEARCH OF LOADS ON DRIVE OF ROD INSTALLATIONS IN LOW SPEED MODE AT HIGH-VISCOUS OIL PRODUCTION

Reliability and power consumption of the rod installations are largely determined by the drive balancing rate. Today, due to the increasing share of hard-to-recover reserves, issues of balance during the extraction of high viscous and paraffinic products, characterized by increased loads on the rod string due to increasing forces of hydrodynamic friction, paraffin deposition on the walls of sucker rods and pipes, are becoming urgent. The effect of the viscosity of the pumped liquid and the degree of paraffinization of the bore of the elevator pipes on the magnitude of the loads on the drive and power consumption of the rod systems, as well as on the optimal position of balancing crank loads, is studied. As a balance criterion, the minimization of the maximum torque on the crank shaft is taken. A mathematical model of the rod installation based on the analytical model of the balancing drive, taking into account the specified kinematics of the four-link mechanism of the rocking machine is developed. When calculating the hydrodynamic friction loads, the Navier-Stokes equations are used for the steady-state fluid flow in the annular space between the rods and tubing. A study of the loads on the drive at various viscosities and degrees of overlap of the cross section of the elevator pipes showed that an increase in the product viscosity (up to 200 mPa ∙ s) and intensive paraffin deposition on the walls of the rods and elevator pipes (overlapping up to 50 % of the cross section of the elevator lift) leads to an increase in the required torque up to 50 % on the crank shaft of the gearbox (the torque applied to the crank and created by the electric motor) and an increase in the consumed electricity and power up to 100 %, i.e. 2 times.

Magnetic Controlled Growth Rods in the Treatment of Scoliosis: Safety, Efficacy and Patient Selection.

Early-onset scoliosis is defined as a spinal curvature greater than 10° in children prior to 10 years of age. Untreated EOS may lead to progressively severe spinal deformity, impaired pulmonary development, restrictive lung disease, and both increased morbidity and mortality. Limitations of established conservative treatments include inability to correct severe deformity, as well as challenges with compliance when casting and bracing is applied. In addition, surgical treatment in the form of traditional growing rods requires regular surgical lengthenings and is associated with complications inherent with repeated invasive procedures and exposure to general anesthesia. MAGEC is an evolving magnetically controlled growing rod system for the treatment of EOS. After initial implantation, lengthening is achieved non-invasively by using magnetic external remote control. MAGEC offers the potential to control moderate and severe EOS, while avoiding repeated surgical procedures and associated complications. In this review, we examine the results from clinical, radiological and explant studies following the use of MAGEC, in the context of other established and emerging treatments for EOS.