End Part Research Articles

Analysis of the Influence of Structural Parameters on the Modes of a Gantry Machine Tool Crossbeam Based on Analytical Method

Modal analysis and structural parameters selection are essential in the structural design of the crossbeam of a gantry machine tool. In order to explore an efficient modal analysis method, the analytical method of modes of the beam with variable cross-section is derived based on the Euler beam theory and transfer matrix method. By dividing the machine tool crossbeam into 27 segments, the crossbeam modes are obtained analytically, which is validated by the finite element method. Compared with the FEM, the analytical method shows high efficiency. On this basis, the influence of various structural parameters, including bending stiffness and linear density, on the crossbeam mode is explored, and the sensitivity analysis is carried out. The results show that the first-order bending frequency of the crossbeam is mainly affected by the bending stiffness in the middle part of the crossbeam, followed by the linear density in the middle and end part. The first-order bending frequency of the crossbeam increases by increasing the bending stiffness in the middle part and decreasing the linear density of the crossbeam. The linear density both in the middle and end part has a great effect on the mode shape of the crossbeam. This study can provide a reference and method for structural design and modal analysis of machine tool crossbeams.

CHARACTERISTICS ANALYSIS OF ADSORBENT FROM RUBBER TREE TRUNK AND RUBBER SEED SHELLS

The efforts to control heavy metal waste are developingg to obtain an economical, effective, and efficient method. One method that is widely used in industry is adsorption. In general, the use of conventional adsorbents requires relatively more expensive operational and regeneration costs, thus it is necessary to investigate alternative adsorbents derived from nature. Local commodities that can be taken as the basic material for adsorbents are rubber plants. In the rubber seed shell there are fibers containing cellulose, hemicellulose, lignin, and waxes. The rubber tree trunk at the base has a relatively high cellulose content (67.38%), the middle part has a cellulose content of (59.37%) and the end part has a cellulose content of (45.73%). Therefore, this study was conducted to determine the potential of rubber stems and rubber seed shell waste to be processed into adsorbents. The making of the adsorbent is preceded by the delignification stage and then followed by the activation process. Based on the characterization tests that have been carried out, it is known that the moisture content in the biosorbent of the rubber seed and shell is 10% and 11%, while the ash content is 1.23% and 2.33%, respectively. The volatile matter levels for the adsorbents from the stems and shells were 6.43% and 6.18%, respectively.The efforts to control heavy metal waste are developingg to obtain an economical, effective, and efficient method. One method that is widely used in industry is adsorption. In general, the use of conventional adsorbents requires relatively more expensive operational and regeneration costs, thus it is necessary to investigate alternative adsorbents derived from nature. Local commodities that can be taken as the basic material for adsorbents are rubber plants. In the rubber seed shell there are fibers containing cellulose, hemicellulose, lignin, and waxes. The rubber tree trunk at the base has a relatively high cellulose content (67.38%), the middle part has a cellulose content of (59.37%) and the end part has a cellulose content of (45.73%). Therefore, this study was conducted to determine the potential of rubber stems and rubber seed shell waste to be processed into adsorbents. The making of the adsorbent is preceded by the delignification stage and then followed by the activation process. Based on the characterization tests that have been carried out, it is known that the moisture content in the biosorbent of the rubber seed and shell is 10% and 11%, while the ash content is 1.23% and 2.33%, respectively. The volatile matter levels for the adsorbents from the stems and shells were 6.43% and 6.18%, respectively.

Gravitational Intelligent Decision-Making Model at the Fuzzy Front End with Extrinsic Idea Integration by the K-Means Algorithm

If the dynamic fuzziness of the Front End (FE) part of New Product Development (NPD) cannot be treated in a timely manner, fuzziness accumulates over other parts of NPD hence NPD can result in costly mistakes. The authors tried to remedy this strategically critical problem by implementing mainstream theoretical/methodological approaches, but they found inherent weaknesses of each. The purpose of this study is to bring an objective and intelligent decision-making model to FE so as to lessen fuzziness of it. Model quantizes ideas based on pillars, and re-clusters them with every new idea addition thanks to combining non-mainstream approaches like K-means, distance-based algorithm with gravitational theory inspiration, an accumulation of idea and an exponential function. Study showed that fuzziness of FE can be lessened by quantizing, and objectively managing. The founded core reasons of fuzziness can guide practitioners and authors for better understanding and coping with fuzziness of FE; moreover, the model can be used by companies. Introducing an objective and intelligent decision-making model working like a human brain to FE is a unique idea that has not been tried ever before.

Experimental and Numerical Evaluation on the Performance of Perfobond Leiste Shear Connectors in Steel-SFRCC Composite Beams.

The difference between the shear performances of Perfobond Leiste (PBL) shear connectors embedded in steel fiber-reinforced cementitious composite (SFRCC) structure and normal strength concrete (NC) structure was investigated by push-out tests and finite element (FE) simulations. Push-out tests were carried out on nine steel-SFRCC specimens and nine steel-NC specimens. The mechanical behavior of the PBL shear connector was examined according to the failure modes, load-slip curves, and strain distribution laws of the push-out specimens. Experimental results revealed that the extension of cracks in SFRCC was hindered by steel fibers, and the number and width of cracks in SFRCC were smaller than those in NC. The failure mode of the steel-SFRCC specimens and the single-hole steel-NC specimens was the shear failure of the penetrating reinforcement, whereas that of the multi-hole NC specimens was concrete slab cracking. The ultimate shear bearing capacity of PBL shear connectors in the steel-SFRCC specimens was 47.8% greater than that in the steel-NC specimens. Furthermore, an FE model verified by the test results was established to conduct parametric analyses. It was found that the hole diameter and thickness of the steel plate and the yield strength of the penetrating rebar greatly affected the shear bearing capacity of PBL shear connectors. Finally, based on the experimental and FE simulation results, an expression for calculating the ultimate shear bearing capacity of PBL shear connectors in the steel-SFRCC composite structure was developed by considering the bearing effects of concrete dowels, penetrating rebars, and end parts.

Numerical and Experimental Investigation on the Performance of Backflow Channel Aerostatic Bearings with Shunt Injection

Simultaneously increasing the load capacity and stiffness of aerostatic bearings is highly significant for ultraprecision machining. To achieve this goal, this study presents a novel method of using backflow channels to divert high-pressure air from the feed pocket to the low-pressure region of the clearance. Different shunt injections are coupled at the end part of the backflow channels. The effects of distribution and structure of the shunt injections are systematically analyzed. Moreover, the experimental data are used to compare and validate the numerically predicted characteristics. Results show that the backflow channels simultaneously enlarge the high-pressure region and improve the load capacity and stiffness of the bearings. The pressure difference between the inherent orifice shunt injections is still evident, which is not beneficial in exploring the potentialities of backflow channels in terms of increasing the load capacity and stiffness of bearings. High-pressure air can be stored under the pocket orifice shunt injection to decrease the pressure difference. Slot shunt injections shaped similar to ramparts can surround the high-pressure air, resulting in a more apparent effect on decreasing the pressure difference. Finally, the load capacity, stiffness, and mass flow rate of the backflow channel bearings are evidently larger than those of pocket orifice bearings. Thus, the growing demand of mass flow rate must also be considered when using backflow channel bearings for their larger load capacity and higher stiffness.

Peculiarities of calculating the diameter of the hole for setting the thread-forming part

The effectiveness of technologies is determined by the total technical effect obtained from their implementation. One of the ways to improve technology efficiency indicators is the introduction of assembly-thread-forming processes based on the use of thread-forming fasteners in product designs. Thread-forming screws, pins, bushings are screwed into smooth holes and form a threaded profile by cutting or deformation. The reduction in labor intensity is achieved by eliminating the operation of preliminary threading, and the resulting connections have high operational and technical indicators. In the production of electronic equipment and devices, where, according to technical requirements, the formation of chips is undesirable, thread-extruding screws are used. Despite the advantages of self-tapping screws, their widespread use is restrained by several disadvantages: the strength of the connection using screws is lower than in the connection using a stud or bolt, screws with an increased pitch have unsatisfactory locking performance, with a diameter of more than 10 mm torque instability and thread profile deformation are observed. Improving the quality of threaded joints by ensuring the optimal size of the hole for threading is the topic of this publication. The calculation of the setting diameter for thread-forming parts with a large step has its own characteristics and must be decided taking into account friction, strength and tolerance. The main causes of surface defects in the installation of thread-forming fasteners are those related to geometry - rolling in a filled contour, which leads to an axial displacement of the surface layers of the metal. Determining the optimal value of the diameter of the hole for screwing the thread-forming part, on the one hand, as large as possible, but not more than the permissible value, is the purpose of this work. The nomenclature of thread-forming fastening elements is constantly expanding, while the ratio of the height of the profile to the step is a variable value even within the limits of one standard. Therefore, the calculation method should be universal, taking into account the conditions of friction, strength, tolerances. Thread forming processes are described as plane deformation processes. Physically, the mechanism of plastic deformation of metals is presented in the form of shifts in planes where the tangential stresses have reached their maximum value. For plane deformation, the trajectories of maximum tangential stresses in two orthogonal directions are described by slip lines, or characteristics. The slip line method allows you to calculate contact stresses and deforming forces, fully determine the fields of stresses and velocities in the sections of deformable metal, and also analyze local phenomena, which are usually fundamental in solving technological problems. The characteristics of plane plastic deformation allow you to find a solution using a graphical method. The use of this method allows you to determine the appearance of the slip line field, or its geometric characteristics, which establish the relationship between the maximum tangential stress and normal hydrostatic pressure, i.e., the deforming force, as well as determine the appearance and geometric parameters of the formed profile, the height of which is limited by the permissible amount of overflow of the profile. Analyzing the geometric parameters of the deformation zone of the threaded turn of the part, the diameter of the hole for the thread-forming fastening part was theoretically justified. The methodology of this calculation is implemented in the form of software and mathematics. These recommendations are related to the geometric parameters of the end part of the self-tapping screw. The results of the work will improve the quality of the connection with the thread-forming fastening part due to the optimization of the diameter of the hole of the part. On the basis of solving the problem of the plasticity theory about the immersion of the indenter into the rigid-plastic region and the analysis of the plastic zone in the region of the largest deformations, the geometric parameters and the appearance of the formed profile are established. The method of using sliding lines allows you to calculate and analyze the geometry visually, to observe the change in the shape of the deformable profile from the ratio of the height of the profile to the pitch of the thread, the material and the coefficient of sliding. This visualization allows you to choose a value of filling the profile even greater than one, when a sufficiently large size of the “crater” of the thread does not allow the profile to overflow. This makes it possible to increase the height of the thread profile and the contact area, as well as to expand the tolerance for the hole in the part. As a result, we have an increase in the strength of the connection and the reliability of the assembly process.

SOCIOLOGICAL EXPLANATION AND RELATIONSHIP OF TERRORISM AND POLITICAL PARTICIPATION: A QUALITATIVE APPROACH

Terrorism and political participation are broadly defined in almost every course of study. The current research article is an attempt to define and explore both terrorism and political participation under the umbrella of sociology and sociological theory. There are mainly three broader perspectives of the sociological theory, like Functionalist perspective, Conflict perspective and Symbolic interactionist perspective and both the terms have been thoroughly analyzed and defined under these basic sociological perspectives. Though academically, both the concepts are moving in the opposite direction, yet there is an intense need to combine them and analyze them with the cover of sociological imagination. The first part of the article comprises theoretical definitions of both the terms with a comprehensive touch of sociological theory and the second part of the article encompasses an attempt to establish an inclusive relationship of both terms. The end part of the article covers the concluding remarks on the basis of definitions of the terms and the establishment of a relationship between both the terms. Key words: Terrorism, Political Participation, Sociological theory, Functionalist perspective, Conflict perspective and Symbolic interactionist perspective

A Radiological Study on the Location of Nasolacrimal Duct in Koreans

Background and Objectives The prelacrimal recess (PA) approach can be used to remove PA lesions while preserving the nasolacrimal duct (NLD). In this regard, it is important to understand the anatomical structure of NLD in relation to the lateral nasal wall. The purpose of this study was to measure NLD and the surrounding structure using the sinus CT.Subjects and Method We used the coronal, axial, and sagittal images to measure the following areas: a distance (M1) between nostril and the most anterior part of the lower end of NLD (NLD-LE); a vertical distance (M2) between the attachment line of inferior turbinate (IT) to lateral wall and the NLD-LE; a distance (M3) between the NLD-LE and nasal cavity floor (NF); a diameter (M4) of the NLD-LE; and an angle (M5) between NF and the extended line of the diameter of the NLD-LE.Results The right side of M1 was 26.45±3.69 mm and the left was 25.95±3.77 mm. The right side of M2 was 1.36±2.07 mm and the left was 0.98±1.86 mm. The right side of M3 was 17.39±3.46 mm and the left was 17.52±3.15 mm. The right side of M4 was 7.89±1.66 mm and the left was 7.96±1.60 mm. The right side of M5 was 46.69°±9.97° and the left was 45.04°± 10.25°.Conclusion In Korean adults, on the average, the NLD-LE was present at 25 mm and 45° from the nasal entrance, 17 mm above the NF, and the diameter of NLD-LE was 8 mm. The NLD-LE is adjacent to the lateral wall attachment of the IT, but there may be individual differences.

The use of detailed kinetics for modeling aerospace propulsion devices

A three-dimensional numerical simulation of a combustion chamber with a continuous rotating detonation wave was studied. A nozzle-type main system feeding was located at the end part of the chamber, and an additional feeding from the inner and outer walls of the annular channel was considered. A hydrogen-oxygen mixture was considered as a fuel. A detailed kinetic mechanism by Z. Hong (2010) consisting of 20 reactions with 9 components was used to simulate chemical processes. Various relations of the fuel were considered: lean mixture [H2]:[O2] = 1:1, stoichiometric mixture [H2]:[O2] = 2:1, and rich mixture [H2]:[O2] = 3:1. Besides, either the same mixture, or additional oxygen, or air was supplied from the side-wall feeding system. For all the considered feeding options, a detonation mode was obtained, and the traction characteristics were calculated.

Comparative Study of Electrically Excited Conventional and Homopolar Synchronous Motors for the Traction Drive of a Mining Dump Truck Operating in a Wide Speed Range in Field-Weakening Region

A synchronous homopolar motor (SHM) has a salient pole passive rotor, an excitation winding located on the stator, and no permanent magnets, which ensures high reliability and makes this type of motor a good alternative to motors traditionally used in traction drives. However, there is no comparison between SHMs and conventional brushed synchronous machines for traction applications in the literature. In this paper, the performances of a wound rotor synchronous machine (WRSM) and SHM are theoretically compared at the operating points of a 370 kW dump mining truck drive traction curve that has a 10:1 constant power range in the field weakening region. The nine-phase motors under comparison have the same outer diameter of the stator lamination. Before comparison, both motor designs are optimized using the Nelder–Mead method to minimize the semiconductor inverter rated current and the operating cycle power loss. The main advantages of the WRSM, which was designed, are reduction in stator length, smaller losses, and smaller inverter. The reduction in the total stator length was by 1.23 times taking into account the winding end parts as well. Losses were reduced by 1.21 times for the same radius of the stator lamination. Finally, the cost of power modules of the inverter was decreased by 1.4 times. SHM is more reliable since its rotor does not have an excitation winding and a diode rectifier, as in a WRSM with a brushless exciter. In addition, SHM provides lower consumption of copper, which reduces the total mass and cost of active materials. This article also introduces a new term, “inverter utilization factor”, which can be useful, more informative than motor power factor, when comparing traction drives with different types of motors.

Обоснование регулирования расхода дождевальных аппаратов широкозахватных машин кругового действия

The article discusses the issues of substantiating the reliability of the movement of wide-reach circular sprinkler machines on elevated slopes by eliminating surface runoff in the movement zone of their running systems, especially in the end part, by equipping sprinkler machines with advanced membrane-type flow regulators. Laboratory studies have determined that the accuracy of regulation by the im-proved regulator is within the same limits as for its serial model, and is ± 5%. It has been found that the regulation of the flow rate of sprinklers in the end part of the DM on a sloping surface increases the value of the bearing capacity of the soil, from 40-50 to 80-90 kPa, or that at a specific pressure of running systems, on average, about 85 kPa, provides sufficient permeability

Vibration Prediction of the Robotic Arm Based on Elastic Joint Dynamics Modeling

The flexibility of the joint drive system of an industrial robot can cause vibration at the end part, which can lead to motion errors. A method to predict the vibration during the motion of the robot arm is proposed considering the robot joint flexibility. The method combines the internal transfer function of the drive system and the identification of parameters under external excitation. Firstly, the dynamics of the robot joint system are modeled by a double inertia elastic system. The joint system transfer function from the electromagnetic torque to the arm vibration is obtained according to the dynamics model. To solve the unknown parameters in the transfer function, a vibration dynamics model of the joint arm under the external forces on the arm is developed. According to this model, the equivalent stiffness, damping and load inertia of the joint can be obtained by the direct parametric method. Then, the vibration spectrum of the robot arm is derived from the motor electromagnetic torque and joint dynamics models were used to predict the vibration spectrum of the robot arm. The experiments were conducted on a single-joint robot testbed, and on an articulated industrial robot. In both experiments, the key parameters in the system were determined by impact experiments. Then, the vibration signal of the arm during the robot motion was obtained by electromagnetic torque prediction. The predicted vibration signals are analyzed in comparison with the actual vibration signals. The experimental results both show the validity of the vibration prediction.

Comparative morphological study of the accessory sex glands of immature and mature local breed donkey (Equus asinus)

Eight samples of accessory sex glands of donkey were used to compare between the immature and mature donkey. The morphological parameters were involved position, relation, shape, length, width, and weight of each gland. The results of in immature and mature donkey the ampulla of ductus deferens were spindle shape strcture of ends part of ductus deferens, located dorsaly to the urinary bladder and opened into ejaculatory duct, in immature measured 1.85±0.04cm, 3.81±0.18mm and 0.96±0.02g and in mature measured 7.57±0.01cm,5.67±0.21mm, and 6.87±0.02g in lenghth, width and weight respectively. Vesicular gland of immature donkey was small size located laterally to the ejaculatory duct and cranillay to the prostate gland, while in mature was larger elongated gland extended more laterlly to the body of urinary bladder, in immature measured 2.13±0.03cm, 3.96±0.08mm, 1.28±0.08g and in mature donkey measured 7.97±0.09 cm, 5.76±0.30 mm, 7.53±0.10g in length, width and weight respectively. Prostate of immature was dark brown in color, small bilobed gland, located caudally to the vesicular gland and laterally to the pelvic urthera, while in mature donkey was very dark brown, and large bilobed gland, it was measured 1.76±0.19cm, 3.51±0.20mm, 3.17±0.10g and in mature measured 2.90±0.01cm, 7.88±0.26mm and 6.40±0.20g in length, width and weight respectively.

ROLE OF PADHAABYANGA UPKARMA IN NETRA SWASTHYA

Ayurveda aims in ‘Swasthasya Swasthya Rakshanam Aturasya Vikar Prashamanam’. To maintain swastya or to fulfil the aim ayurveda has mentioned Dincharya, Rutucharya, ect. Padaabhyanga i.e. application of oil to the feet is the part of Dincharya. Since Abhyanga is advised to be done on a daily basis for maintenance of good health, so Padabhyanga too can be done on a daily basis. Padabhyanga can be done at any time of the day; it is more effective when it is done at end part of the evening or at night before going to bed. The hectic computerized life style, Faulty food habits, Stress, Irregular sleeping habits,strain the body and eyes. Oil applied to the feet, makes the feet strong (sthairya) and induces sleep (nidra). According to Charaka and Vagbhata Padaabhyanga is described as Dristiprasadaka and according to Sushruta Chakshushya.

The Effect of Application of Chicken Gelatin on Reducing the Weight Loss of Beef Sirloin after Thawing.

Freezing is one of the oldest and most-often-used traditional methods to prolong the shelf life of meat. However, the negative phenomenon of this process is the weight loss of water that occurs after the meat is thawed. Together with the water that escapes from the meat during thawing, there are large weight losses in this valuable raw material. Another negative aspect is that mineral and extractive substances, vitamins, etc. also leave the meat, resulting in irreversible nutritional losses of nutrients in the meat, which are subsequently missing for use by the consumer of the meat. The main goal of this work is to reduce these losses by using gelatin coatings. Gelatin was prepared from chicken paws according to a patented biotechnological procedure, which uses the very gentle principle of obtaining gelatin with the usage of enzymes. This unique method is friendly to the environment and innocuous for the product itself. At the same time, it ensures that the required principles achieve a circular economy with the use of the so far very-little-used slaughter byproducts, which in most parts of the world end up in uneconomic disposal by burning or landfilling without using this unique potential source of nutrients. Gelatin coatings on the surface of the beef steak were created by immersing the meat in a solution based on gelatin of different composition. A coating containing 3%, 5% or 8% gelatin with 10% or 20% glycerol (by weight of gelatin) and 1% glutaraldehyde crosslinker (by weight of gelatin) has proved to be effective. The amount of glutaraldehyde added to the coating is guaranteed not to exceed the permitted EU/U.S. legislative limits. In addition to weight loss, meat pH, color and texture were also measured. Freezing was done in two ways; some samples were frozen at a normal freezing temperature of −18 °C and the other part of the experiment at deep (shock) freezing at −80 °C. Defrosting took place in two ways, in the refrigerator and in the microwave oven, in order to use the common defrosting methods used in gastronomy. A positive effect of this coating on weight loss was observed for each group of samples. The most pronounced effect of coating was found for the least gentle method of freezing (−18 °C) and thawing (microwave), with the average weight loss of the coated samples differing by more than 2% from that of the uncoated sample. No negative effect of the coating was observed for other meat properties tested, such as pH, Warner-Bratzler Shear Force (WBSF) or color. Gelatin-based coating has a positive effect on reducing the weight loss of meat after thawing. Chicken gelatin prepared by a biotechnological process has a new application in improving the quality of meat due to the retention of water and nutrients in frozen and subsequently thawed beef, which can contribute to the better quality of the subsequently gastronomically prepared dish, while maintaining the weight and nutritional quality. This also results in economic savings in the preparation of highly-valued parts of beef.

An overview of cold spray coating in additive manufacturing, component repairing and other engineering applications

AbstractCold spray process (CSP) is a thermal spray technology in which coating (10–40 µm) is formed in the solid state by the impingement of power particles with supersonic velocity (200–1,200 m/s2) on coupon employing compressed gas jet, below the melting point of coating powder. It is commonly referred as cold gas dynamic spray, high velocity powder deposition, kinetic spray and kinetic energy metallisation process. Using CSP, various engineering materials (metals, polymers and ceramics) and its composites can be deposited. It is unique and promising approach for obtaining surface coating and offers various technological benefits over thermal spray as kinetic energy is employed for deposition rather than thermal energy. This offers great benefits in additive manufacturing (AM) to develop a component denser, low oxide coating free of tensile residual stresses, and undesired chemical reactions compared to conventional AM and coating techniques. Cold spray additive manufacturing (CSAM) is the powerful and emerging technique in the field of AM to develop engineering components with improved performance covering broad range of functionalities of surface, subsurface and interfaces. There are few flaws in this technique; however, extensive research work is going in CSAM and repairing of components to meet the real-time applications. The main objective of this review article is to summarise the history, effect of process parameters on surface coating, research and development in CSP along with its implementation in AM, component repairing and biomedical, antimicrobial and electrical applications. A discussion on future trends in CSAM is also provided at the end part of this article.

Moisture transfer and drying stress of eucalyptus wood during supercritical CO2 (ScCO2) dewatering and ScCO2 combined oven drying

Supercritical CO2 (ScCO2) dewatering is a lumen water expulsion process, in which CO2 is cycled between atmospheric pressure and supercritical phase and results in a fast expulsion of free water. In this study, specimens of 100 mm length Eucalyptus exserta F.V. Muell. wood were dewatered using ScCO2, then the dewatered and un-dewatered wood were dried in oven at 100 °C to investigate moisture transfer and drying stress. The ScCO2 dewatering was very fast. When the moisture content (MC) was over 40%, the MC distribution and gradient after dewatering and oven drying were different. The oven drying MC showed a ring contour distribution, but the ScCO2 showed a higher MC in one side and a lower MC in the opposite; the oven drying MC gradient was great in the middle and small in the end part of wood, but the ScCO2 MC gradient was small and roughly consistent. The oven drying moisture migration rates along the fiber and transverse directions were similar; however, the ScCO2 migration rate was faster in the transverse directions. The MC distributions of the dewatered and un-dewatered wood after oven drying were similar at 30% MC. The ScCO2 dewatering reduced wood residual stress, and it affected the stress development in the subsequent oven drying.

Dimeric G‐quadruplex DNA Structure in the Proximal Promoter of VEGFR‐2 Reveals a New Drug Target to Inhibit Tumor Angiogenesis

Comprehensive SummaryVascular endothelial growth factor (VEGF) regulates tumor angiogenesis, which is active on the endothelium via VEGF receptor 2 (VEGFR‐2). The proximal promoter region of VEGFR‐2 (termed as VEGFR‐2 DNA) is guanine‐rich, forming G‐quadruplex (G4) structures. Here, we demonstrate that VEGFR‐2 DNA consists of one symmetrically dimeric 14‐mer G4‐DNA and one 12‐mer sequence‐palindromic dsDNA. This G4‐DNA adopts an unprecedented folding with five stacked tetrads linked by four broken strands. Its 5’‐end part contains an A‐tetrad A1•A4•A1’•A4’ and one G‐tetrad G3•G5•G3’•G5’ with two V‐shaped loops and two one‐nt edge‐type loops. Its 3’‐end part includes three G‐tetrads G10•G6•G10’•G6’, G11•G7•G11’•G7’ (central) and G12•G8•G12’•G8’ spanned by two double‐chain‐reversal one‐nt (C9 or C9’) loops. Bases G13 and G13’ stack with G‐tetrad G12•G8•G12’•G8’. These characteristics make this G4‐DNA more stable than reported VEGFR‐17T G4 structure. The dsDNA connects with G4‐DNA without any interactions, generating a linear assembly with G4‐DNA structural bulges. These studies uncover new structural features of VEGFR‐2 DNA as a potential drug target by inhibiting VEGFR‐2 expression, thereby tumor angiogenesis.

Statistical properties and correlation length in star-forming molecular clouds

Observations of molecular clouds (MCs) show that their properties exhibit large fluctuations. The proper characterization of the general statistical behavior of these fluctuations, from a limited sample of observations or simulations, is of prime importance to understand the process of star formation. In this article, we use the ergodic theory for any random field of fluctuations, as commonly used in statistical physics, to derive rigorous statistical results. We outline how to evaluate the autocovariance function (ACF) and the characteristic correlation length of these fluctuations. We then apply this statistical approach to astrophysical systems characterized by a field of density fluctuations, notably star-forming clouds. When it is difficult to determine the correlation length from the empirical ACF, we show alternative ways to estimate the correlation length. Notably, we give a way to determine the correlation length of density fluctuations from the estimation of the variance of the volume and column-density fields. We show that the statistics of the column-density field is hampered by biases introduced by integration effects along the line of sight and we explain how to reduce these biases. The statistics of the probability density function (PDF) ergodic estimator also yields the derivation of the proper statistical error bars. We provide a method that can be used by observers and numerical simulation specialists to determine the latter. We show that they (i) cannot be derived from simple Poisson statistics and (ii) become increasingly large for increasing density contrasts, severely hampering the accuracy of the high end part of the PDF because of a sample size that is too small. As templates of various stages of star formation in MCs, we then examine the case of the Polaris and Orion B clouds in detail. We calculate, from the observations, the ACF and the correlation length in these clouds and show that the latter is on the order of ~1% of the size of the cloud. This justifies the assumption of statistical homogeneity when studying the PDF of star-forming clouds. These calculations provide a rigorous framework for the analysis of the global properties of star-forming clouds from limited statistical observations of their density and surface properties.

Experimental Study of Emulative Precast Concrete Beam-to-Column Connections Locally Reinforced by U-Shaped UHPC Shells.

Precast beam–column connections act as vital elements of precast concrete frames. To enhance the resistance to the earthquake-induced damage and environment-induced deterioration of precast beam–column connections, an innovative precast concrete beam-to-column connection locally enhanced by prefabricated ultra-high-performance concrete (UHPC) shells was proposed. For studying the seismic behaviors of these novel connections and the influence caused by the prefabricated UHPC shell length, full-scale precast specimens were experimentally investigated using low-cyclic reversed loading tests. The obtained results were analyzed and discussed, including hysteresis curves, skeleton curves, strength and deformability, performance degradation, energy dissipation capacities, and plastic hinge length. The results reveal that the novel precast concrete beam–column connections with UHPC shells behaved satisfactorily under seismic loadings. The damage in the concrete near the lower part of the beam end is reduced by the prefabricated UHPC shells. The longer prefabricated UHPC shells were more useful for decreasing the damage to the precast concrete components and improved the structural performance. The precast specimen with 600-mm long UHPC shells can achieve a ductility of 4.87 and 4.0% higher strength than the monolithic reference specimen.