Overhanging End Research Articles

Study on Seismic Behavior and Influencing Factors of Composite Connection in Moment-resisting Steel Frame

To study the seismic behavior and influencing factors of prefabricated steel frame composite joints, cyclic loading tests of two groups of scaled specimens were carried out, and the refined numerical model was established and its validity was verified. The failure mode, hysteretic behavior and moment-rotation curve of composite joints and pure steel joints were compared, and the influence of composite slab on the mechanical properties of joints was summarized. At the same time, the parameters of the key components were selected as variables to study the changing law of the stress properties of the joints. The results indicate that the main failure modes of the overhanging end plate connection are end plate yield, bolt breakage and stiffener buckling, and the composite joints will also have local crushing of composite slab. The factors that significantly affect the bearing capacity and initial rotational stiffness of joints include the thickness of end plate, the setting of end plate stiffener, the extension of end plate, the strength of steel, the thickness of slab and the diameter of steel bars. In addition, the shape of end plate stiffeners has obvious influence on the stress distribution of joints. Finally, the calculation model of the overhanging end plate connection composite joint's initial rotational stiffness was proposed, and the stiffness superposition method was used to consider the bending stiffness of the end plate. At the same time, its reliability and high accuracy were verified, which was of great significance to engineering application.

Analysis and Treatment of Generator Vibration Faults in a Power Plant

This paper presents a detail research on a vibration high fault after overhaul occurred on a generator. During the overhaul, the generator rotor is returned to factory for processing and replaces section across the line of the generator excitation end. The gas turbine unit vibrates high in the idle 3000 r·min−1 and full load. The large vibration of the generator is mainly caused by the following two factors:the imbalance in the overhanging end of the generator rotor and the electrical fault in the generator itself. The unbalanced amount of generator overhang was successfully eliminated by dynamic balance test. The electrical fault of generator itself needs to be returned to the factory to handle.

Interfacial stresses in reinforced concrete cantilever members strengthened with fibre-reinforced polymer laminates

Fibre-reinforced polymers have been increasingly used to strengthen reinforced concrete structures. However, premature brittle debonding failures may occur at the ends of externally bonded fibre-reinforced polymer laminates due to interfacial stress concentrations caused by stiffness imbalances. Although many studies exist on fibre-reinforced polymer-strengthened simply supported beams and slabs, the interfacial stress distributions in fibre-reinforced polymer-strengthened cantilever members are very different from those in simply supported members. Based on the assumptions of linear elasticity, deformation compatibility and static equilibrium conditions, the interfacial stresses in fibre-reinforced polymer-strengthened reinforced concrete cantilever members under arbitrary linear distributed loads were analysed. In particular, closed-form solutions were obtained to calculate the interfacial stresses under either a uniformly distributed load or a single concentrated load located at the overhanging end of the cantilever member. Existing test results on cantilever slabs strengthened by carbon fibre–reinforced polymer sheets were used to verify the model. According to the parametric analysis, the maximum interfacial stresses can be reduced by decreasing the fibre-reinforced polymer thickness, increasing the fibre-reinforced polymer bonding length and increasing the adhesive layer thickness, and by using less rigid fibre-reinforced polymer laminates with high tensile strengths. These results are useful for engineers seeking to optimize strengthening design parameters and implement reliable debonding prevention measures.

Analysis of Causes of Generator Vibration Faults and Rotor Cracking in a Power Plant

The vibration of a generator in a power plant and the cause of rotor cracking wereanalyzed. The causes of generator rotor cracking were analyzed from the rotor raw material andheat treatment process. The results show that the brittleness and notch sensitivity of the rotormaterial are large due to the unreasonable heat treatment process of the rotor. When the stress isconcentrated, a cracking accident occurs. The generator rotor was returned to the manufacturingcompany for operation. At 3000 r•min-1, the generator's overhanging end vibrated greatly, and thefault was successfully eliminated by the dynamic balance test.

Investigations on the fatigue behavior of end plate connections with prestressed bolts

In many areas of our infrastructure, as for instance the construction of crane runway beams, fatigue design of steel structures is a major issue. An important detail in practice, but insufficiently classified in the (Eurocode 3-1-9, 2005) detail catalogue, is the end plate connection with prestressed bolts. Detailed numerical simulations are often necessary for the fatigue check of the weld at the T-stub. The knowledge of the true bolt force required in the detail catalogue can usually also only be taken into account using finite element simulations. For these reasons, the detail ‘end plate connection with different weld configurations and prestressed bolts’ containing the two critical design cases mentioned above has been investigated. The analyzed details comprise butt welds as well as fillet welds and connections with overhanging and flush end plate connections.A literature review of fatigue in details of end plate connections is given. Moreover, the test program on three fatigue tests series is presented. After conducting experimental investigations on small-scale as well as large-scale specimens detailed numerical simulations have been realized. In order to assess the fatigue resistance of the welded connection, the effective notch stress concept has been used. Additionally, fatigue resistances of prestressed bolts have been investigated by recalculating the bolt force progress. After the verification of the numerical models, a parametric study has been conducted by varying geometric characteristics in order to give recommendations on the design of prestressed bolts and welds in end plate connections.

Strand Displacement in Coiled-Coil Structures: Controlled Induction and Reversal of Proximity.

Coiled-coil peptides are frequently used to create new function upon the self-assembly of supramolecular complexes. A multitude of coil peptide sequences provides control over the specificity and stability of coiled-coil complexes. However, comparably little attention has been paid to the development of methods that allow the reversal of complex formation under non-denaturing conditions. Herein, we present a reversible two-state switching system. The process involves two peptide molecules for the formation of a size-mismatched coiled-coil duplex and a third, disruptor peptide that targets an overhanging end. A real-time fluorescence assay revealed that the proximity between two chromophores can be switched on and off, repetitively if desired. Showcasing the advantages provided by non-denaturing conditions, the method permitted control over the bivalent interactions of the tSH2 domain of Syk kinase with a phosphopeptide ligand.

Strand Displacement in Coiled‐Coil Structures: Controlled Induction and Reversal of Proximity

AbstractCoiled‐coil peptides are frequently used to create new function upon the self‐assembly of supramolecular complexes. A multitude of coil peptide sequences provides control over the specificity and stability of coiled‐coil complexes. However, comparably little attention has been paid to the development of methods that allow the reversal of complex formation under non‐denaturing conditions. Herein, we present a reversible two‐state switching system. The process involves two peptide molecules for the formation of a size‐mismatched coiled‐coil duplex and a third, disruptor peptide that targets an overhanging end. A real‐time fluorescence assay revealed that the proximity between two chromophores can be switched on and off, repetitively if desired. Showcasing the advantages provided by non‐denaturing conditions, the method permitted control over the bivalent interactions of the tSH2 domain of Syk kinase with a phosphopeptide ligand.

Influence of Structural Design of Balcony Panels on the Course and the Size of Thermal Bridges

This paper is focused on the static and thermal protection issues of the balcony panels design. The projecting part of the balcony panel, which is from a static point of view an overhanging end of a simply supported beam, is exposed to the direct effects of climate variations. Insulation of projecting part of the balcony panel is simple, but rarely applicable in practice, mainly due to a thickness of this cantilever structure with thermal insulation and balcony floor structure and therefore difficult height arrangement at the entrance to the balcony and problematic realization of the facade. Therefore, thermal insulation is usually placed at the edge of a single-leaf masonry or in the place of thermal insulation, which is place of the biggest static loading on the overhanging part of balcony panel. Possible solutions of contradictory requirements of statics and thermal protection and the impact of structural design on the course and the size of thermal bridges in the building envelope are shown on the analysis of balcony panels.

Deformation Compensation of Ram Components of Super-heavy-duty CNC Floor Type Boring and Milling Machine

Ram is a very important component of super-heavy-duty computer numerical control (CNC) floor type boring-milling machine, and deformation of ram is a significant source causing errors in machining process. To compensate the deformation error of super-heavy-duty CNC floor type boring-milling machine, based on force analysis theory, the law and compensation measures of deformation of ram are researched. Based on the principle of torque (force) balance of the ram components, the formulas of compensation forces and compensation torques are derived, the relations between compensation forces (compensation torques) and the stroke distance of the ram are given. According to theoretical analysis results and the structural characteristics of super-heavy-duty CNC floor type boring and milling machine of TK6932, rods compensation, hydrostatic pressure compensation and wire rope compensation measures are taken to compensate the deformation error of ram. The experiments and computer simulation results show that the straightness of the ram at its overhanging end meets the national machinery industry standards.

Biplane double-supported screw fixation (F-technique): a method of screw fixation at osteoporotic fractures of the femoral neck

The present work introduces a method of screw fixation of femoral neck fractures in the presence of osteoporosis, according to an original concept of the establishment of two supporting points for the implants and their biplane positioning in the femoral neck and head. The provision of two steady supporting points for the implants and the highly increased (obtuse) angle at which they are positioned allow the body weight to be transferred successfully from the head fragment onto the diaphysis, thanks to the strength of the screws, with the patient’s bone quality being of least importance. The position of the screws allows them to slide under stress with a minimal risk of displacement. The method was developed in search of a solution for those patients for whom primary arthroplasty is contraindicated. The method has been analysed in relation to biomechanics and statics. For the first time, a new function is applied to a screw fixation—the implant is presented as a simple beam with an overhanging end.

Cloning of complete genes for novel hydrolytic enzymes from Antarctic sea water bacteria by use of an improved genome walking technique

The increased demand for enzymes with new properties makes indispensable the development of easy and rapid strategies to obtain complete genes of new enzymes. Here a strategy is described which includes screening by PCR of new subtilases mediated by Consensus-Degenerate Hybrid Oligonucleotide Primers (CODEHOP) and an improved genome walking method to obtain the complete sequence of the identified genes. Existing methods of genome walking have many limitations, which make them inefficient and time consuming. We have developed an improved genome walking method with novel advances to get a simple, rapid and more efficient procedure based on cassette-ligation. Improvements consist basically in the possibility of a genomic DNA digestion with any restriction enzyme, blunting and 3′ adenylation of digested DNA by Taq DNA polymerase to avoid self-circularization, followed by TA ligation of the adenine 3′ overhanging end to the same unphosphorylated oligo-cassette. The efficiency of the genome walking method was demonstrated by finding the unknown ends of all gene fragments tested, previously obtained by CODEHOP-mediated PCR, including three subtilases (P4, P6 and P7), one xylanase and one lipase, from different strains of Antarctic marine bacteria.

Cernunnos/XLF promotes the ligation of mismatched and noncohesive DNA ends

Nonhomologous end-joining (NHEJ) repairs DNA double-strand breaks created by ionizing radiation or V(D)J recombination of the immunoglobulin genes. The breaks often leave mismatched or nonligatable ends, and NHEJ must repair the breaks with high efficiency and minimal nucleotide loss. Here, the NHEJ proteins Ku, DNA-dependent protein kinase catalytic subunit, XRCC4/Ligase IV, and Cernunnos/XRCC4-like factor joined mismatched and noncohesive DNA ends in the absence of processing factors. Depending on the mismatch, Cernunnos stimulated joining 8- to 150-fold. For substrates with a blunt end and a 3' overhanging end, Ku, XRCC4/Ligase IV, and Cernunnos ligated the 3' overhanging hydroxyl group to the 5' phosphate of the blunt end, leaving the other strand unjoined. This activity provides a mechanism for retaining 3' overhang sequences, as observed during V(D)J recombination in vivo. Thus, Cernunnos/XRCC4-like factor promotes a mismatched end (MEnd) DNA ligase activity to facilitate joining and to preserve DNA sequence. Furthermore, MEnd ligase activity may have applications in recombinant DNA technology.

Correlation between Microarray DNA Hybridization Efficiency and the Position of Short Capture Probe on the Target Nucleic Acid

The hybridization behavior of small oligonucleotides arrayed on glass slides is currently unpredictable. In order to examine the hybridization efficiency of capture probes along target nucleic acid, 20-mer oligonucleotide probes were designed to hybridize at different distances from the 5' end of two overlapping 402- and 432-bp ermB products amplified from the target DNA. These probes were immobilized via their 5' end onto glass slides and hybridized with the two labeled products. Evaluation of the hybridization signal for each probe revealed an inverse correlation with the length of the 5' overhanging end of the captured strand and the hybridization signal intensity. Further experiments demonstrated that this phenomenon is dependent on the reassociation kinetics of the free overhanging tail of the captured DNA strand with its complementary strand. This study delineates key predictable parameters that govern the hybridization efficiency of short capture probes arrayed on glass slides. This should be most useful for designing arrays for detection of PCR products and nucleotide polymorphisms.

A viral protein suppresses RNA silencing and binds silencing-generated, 21- to 25-nucleotide double-stranded RNAs.

Posttranscriptional gene silencing (PTGS) processes double-stranded (ds) RNAs into 21-25 nucleotide (nt) RNA fragments that direct ribonucleases to target cognate mRNAs. In higher plants, PTGS also generates mobile signals conferring sequence-specific silencing in distant organs. Since PTGS acts as an antiviral system in plants, successful virus infection requires evasion or suppression of gene silencing. Here we report that the 19 kDa protein (p19) of tombusviruses is a potent silencing suppressor that prevents the spread of mobile silencing signal. In vitro, p19 binds PTGS-generated, 21-25 nt dsRNAs and 21-nt synthetic dsRNAs with 2-nt 3' overhanging end(s), while it barely interacts with single-stranded (ss) RNAs, long dsRNAs or blunt-ended 21-nt dsRNAs. We propose that p19 mediates silencing suppression by sequestering the PTGS-generated 21-25 nt dsRNAs, thus depleting the specificity determinants of PTGS effector complexes. Moreover, the observation that p19-expressing transgenic plants show altered leaf morphology might indicate that the p19-targeted PTGS pathway is also important in the regulation of plant development.

Modified purine nucleosides as dangling ends of DNA duplexes: the effect of the nucleobase polarizability on stacking interactions

Base-modified nucleotide residues have been appended to the 5′-terminus of the self-complementary oligo-2′-deoxynucleotide duplex [5′-d(CGCGCG)]2 as dangling ends. Temperature-dependent UV measurements on the resulting oligomers indicate generally higher thermal stabilities (Tm) compared to that without an overhanging end. The duplex stabilization (ΔTm) was correlated with the molecular polarizability (αm) of the base of the pendant nucleoside showing that: the higher the molecular polarizability αm of a dangling nucleobase, the higher the thermal stability of the DNA duplex.

Rad51 Uses One Mechanism to Drive DNA Strand Exchange in Both Directions

The Rad51 protein of Saccharomyces cerevisiae, like its bacterial counterpart RecA, promotes strand exchange between circular single-stranded DNA (ssDNA) and linear double-stranded DNA (dsDNA) in vitro. However, the two proteins differ in the requirement for initiating joint molecules and in the polarity of branch migration. Whereas RecA initiates joint molecules from any type of ends on the dsDNA and branch migration proceeds exclusively in the 5'- to 3'-direction with respect to the single strand DNA substrate, initiation mediated by Rad51 requires a complementary 3' or 5' overhanging end of the linear dsDNA and branch migration proceeds in either direction. Here we report that the rates of Rad51-mediated branch migration in either the 5'- to 3'- or 3'- to 5'-directions are affected to the same extent by temperature and MgCl(2). Furthermore, branch migration in both directions is equally impeded by insertions of non-homologous sequences in the dsDNA, inserts of 6 base pairs or more being completely inhibitory. We have also found that the preference of strand exchange in the 5'- to 3'-direction does not change if RPA is replaced by Escherichia coli SSB or T4 gene 32 proteins, suggesting that the preference for the direction of strand exchange is intrinsic to Rad51. Based on these results, we conclude that Rad51-promoted branch migration in either direction occurs fundamentally by the same mechanism, quite probably by stabilizing successively formed heteroduplex base pair.

Branch migration during Rad51-promoted strand exchange proceeds in either direction.

The Saccharomyces cerevisiae Rad51 protein is important for genetic recombination and repair of DNA double-strand breaks in vivo and can promote strand exchange between linear double-stranded DNA and circular single-stranded DNA in vitro. However, unlike Escherichia coli RecA, Rad51 requires an overhanging complementary 3' or 5' end to initiate strand exchange; given that fact, we previously surmised that the fully exchanged molecules resulted from branch migration in either direction depending on which type of end initiated the joint molecule. Our present experiments confirm that branch migration proceeds in either direction, the polarity depending on whether a 3' or 5' end initiates the joint molecules. Furthermore, heteroduplex DNA is formed rapidly, first at the overhanging end of the linear double-stranded DNA's complementary strand and then more slowly by progressive lengthening of the heteroduplex region until strand exchange is complete. Although joint molecule formation occurs equally efficiently when initiated with a 3' or 5' overhanging end, branch migration proceeds more rapidly when it is initiated by an overhanging 3' end, i.e., in the 5' to 3' direction with respect to the single-stranded DNA.

Characterization of strand exchange activity of yeast Rad51 protein.

The Saccharomyces cerevisiae RAD51 gene product takes part in genetic recombination and repair of DNA double strand breaks. Rad51, like Escherichia coli RecA, catalyzes strand exchange between homologous circular single-stranded DNA (ssDNA) and linear double-stranded DNA (dsDNA) in the presence of ATP and ssDNA-binding protein. The formation of joint molecules between circular ssDNA and linear dsDNA is initiated at either the 5' or the 3' overhanging end of the complementary strand; joint molecules are formed only if the length of the overhanging end is more than 1 nucleotide. Linear dsDNAs with recessed complementary or blunt ends are not utilized. The polarity of strand exchange depends upon which end is used to initiate the formation of joint molecules. Joint molecules formed via the 5' end are processed by branch migration in the 3'-to-5' direction with respect to ssDNA, and joint molecules formed with a 3' end are processed in the opposite direction.