Experience Study on Long-Life Microsurfacing with High Water Resistance Performance

Microsurfacing is a standard preventive maintenance technology developed on the basis of slurry sealing technology. However, the high temperature and rainy season in Guangdong Province affect its expanded application because of its low water resistance and short service life. So, high-performance microsurfacing, a new microsurfacing technology, has been developed. The key to this technique is an appropriate proportion of water-based epoxy resin and waterborne epoxy curing agent, which could generate a chemical reaction to form a high-performance bonding network structure of space. And indoor wet-wheel wear test shows that its antiwear ability and resistance to water damage are evidently increased (to over 50%) compared with the conventional microsurfacing. Furthermore, from the long-term road performance results, the antisliding and water resistance performance of high-performance microsurfacing is much higher than the conventional technique.

Solar Radiation Transmittance Characteristics of Textile Woven Fabrics suitable for Greenhouse covering Materials

Nowadays, greenhouse covering materials have a vital role in terms of a protective cultivation process. Many farmers use polyfilms, rigid or semi-rigid plastic panels, and glazing materials as greenhouse covering materials in the present scenario. However, these plastic covering materials are known for their high cost, short service life, and cause of harmful environment. Solar transmittance property is one of the main criteria for choosing any greenhouse covering materials. This study prepares various woven fabrics made of polyester, cotton, and polyester–cotton blend yarns. Their solar transmittance characteristic is analyzed to develop fabric and compare it with a polyethylene film already used as a greenhouse cladding material to substitute for plastic materials. The solar transmission of polyester fabric is achieved as high as 70% in the photosynthesis active radiation, suitable for a commercial greenhouse material. In addition, the polyester fabric has tensile strength and extension much higher than that of commercial plastic greenhouse material.

PROSPECTS FOR THE USE OF STRUCTURAL MATERIAL BASED ON LOW-VALUE SOFT HARDWOOD WOOD FOR BRIDGES ON HARVESTING ROADS

Russia has significant reserves of low-value soft deciduous wood (birch, aspen, alder, poplar), which are practically not processed, the wood rots in the forest and in the lower warehouses. Wood is a good and widespread building material. Due to the significant strength, low volume weight, ease of processing, ease of manufacturing and assembly of structures, wood has long been used for the construction of bridges. At present, despite the widespread use of reinforced concrete bridges, in the forest-rich northern and eastern regions of Russia, wooden bridges can be very useful on logging roads. But wooden bridges have a number of significant drawbacks: they have a short service life, are subject to rot, are not fire-resistant, and do not meet the requirements for passing modern loads. In order to ensure the safe and uninterrupted transport of timber on logging roads, special attention should be paid to the construction material for the construction of bridges. The proposed construction material is based on low-value soft hardwood, has high performance characteristics. To improve the performance of the wood, it is necessary to impregnate it-giving it the desired properties and compress it-thereby increasing the density, hardness and strength. We have developed a technology that combines three main technological operations of wood modification: impregnation, pressing and drying, while allowing us to obtain a structural material with increased performance characteristics, suitable for the manufacture of load-bearing supports, as well as beams of wooden bridges on logging roads.

Determination of an Extrusion Machine Performance Based on the Working Field of the Extruder Die

Some inventions along with theoretical and experimental research made it possible to increase the output of a thermally homogeneous melt provided by the screw. However, the quality of the extruded product depends on some specific features of the extrusion die and to a large extent on the rheological behavior (viscous and elastic) of the polymer melt. The mismatch between the design of the screw-cylinder subassembly and the design of the extrusion die results in products with relatively short service life. The present paper has drawn up the working field of the extruder die and adjusted it based on the limitations imposed by the screw-cylinder subassembly, namely: - the maximum output rate that ensures the required thermal homogeneity of the melt; - the maximum output at which the heating system on the barrel (and possibly the screw) ensures the extrusion temperature; - the minimum economic output corresponding to the diameter of the screw. The working field of some extrusion dies for blown films of the following polymers have been plotted: polypropylene, low density polyethylene, high density polyethylene and ethylene vinyl acetate.

History of the use of autologous materials in aortic valve surgery

<p>Various types of autologous materials are used in heart valve surgery, particularly the aortic valve, and this article describes their historical development. The evolution of the use of various autogenous tissues, such as the aortic wall, fascia lata of the thigh, pericardium and others is described and discussed in detail. This paper presents the results of experimental and clinical publications devoted to the surgical techniques and the outcomes of heart valve reconstruction using such materials. The negative aspects of the use of a wide range of autografts are discussed, including the short service life and low strength, which led to declining interest in this group of reconstructive interventions. The method for treating the autopericardium with glutaraldehyde, proposed in 1986 by C.S. Love, J.W. Love and colleagues, raised the use of autologous materials in the reconstruction of heart valves to a new level, allowing surgeons to strengthen the autopericardial flaps and increase resistance to hemodynamic stress. Many surgeons, their interest in such treatment methods increased by this discovery, then reported their observations and further developed ways of using the treated autopericardium in aortic valve surgery. Particularly, the method of neocuspidisation of the aortic valve, introduced into wide practice by M.G. Duran and S. Ozaki, has become the quintessential reconstructive valve surgery involving the use of autologous materials.</p><p>Received 14 March 2021. Revised 26 April 2021. Accepted 27 April 2021.</p><p><strong>Funding:</strong> The study did not have sponsorship.</p><p><strong>Conflict of interest:</strong> The authors declare no conflicts of interests.</p><p><strong>Contribution of the authors</strong><br />Conception and study design: A.O. Simonyan, A.M. Ismailbaev<br />Drafting the article: A.O. Simonyan, A.M. Ismailbaev, N.O. Kurasov, M.I. Tcheglov<br />Critical revision of the article: R.N. Komarov, V.V. Dalinin, I.A. Borisov<br />Final approval of the version to be published: R.N. Komarov, A.O. Simonyan, I.A. Borisov, V.V. Dalinin, A.M. Ismailbaev, N.O. Kurasov, M.I. Tcheglov</p>

A self-healing fluorine-free superhydrophobic cotton fabric under heat stimulation

Superhydrophobic cotton fabrics have been widely explored for their excellent properties, although there are still a few limitations in the practical applications for the reasons of poor environmental performance and short service life. In this study, the hexadecyltrimethoxysilane emulsion was prepared using O2-plasma and ultrasound for the superhydrophobic functional finishing of raw cotton fabric by immersion method. The prepared cotton fabrics showed a superior hydrophobicity with water contact angles larger than 156.0°, as well as an excellent self-healing ability. This self-healing ability was gained by simple heating treatment, which could restore the superhydrophobicity of the hydrophilic cotton fabric damaged by abrasion or O2-plasma treatment. The superhydrophobic cotton fabrics demonstrated excellent washing durability, which can withstand 50 times accelerated laundering cycles. Besides this, the superhydrophobic coatings also displayed fair chemical stability in strong acidic and alkaline solutions. The prepared nonfluorinated superhydrophobic cotton fabric with self-healing ability shows a potential for practical functional textile application.

Experimental Investigation of Transfer of PTFE on Bearing Steel

Polytetrafluoroethylene (PTFE) lubricant is commonly applied for dry contact due to its low friction properties. However, low strength properties can lead to short service-life due to high wear rate, especially under high contact load. The method to add PTFE into a solid contact during operation as a transfer layer has been one of the major attempts in this field. This study aims to investigate the influence of operating parameters, i.e., revolution cycle, sliding speed and applied load, on coverage area of transfer PTFE on the bearing steel (AISI 52100) disc. The experiments were performed on the modified pin-on-disc apparatus using a unidirectional ground disc. The areas with disc grinding direction parallel (parallel morphology) and perpendicular (perpendicular morphology) to the pin sliding direction were both examined. The ascending of transfer coverage area with an increasing revolution cycle within the first 1000 cycle was observed on the area with a sliding direction perpendicular to the disc grinding direction while the descending of transfer coverage area was found on the parallel case. The further increase in the revolution cycle led to only a small change in the transfer coverage area. With more revolution cycles, the pin wear rate increased as a decrease in transfer coverage area formed on the counter-face. Research suggested that the amount of transfer coverage area decreased with increasing sliding speed. However, it could be increased by increasing the applied load.

Experimental Study on Sulfate Erosion Resistance of Nano-CaCO3 Modified Concrete

In the saline soil environment of western China, the salts can corrode the ordinary cement concrete seriously, and the durability of concrete structure deteriorates gradually until it fails. This impedes the application of ordinary Portland cement concrete in this area. Aiming at the problem of the short service life of concrete in the harsh environment of western China, this study probes the performance of nano-CaCO₃ modified concrete in a sulfate environment. The durability of the concrete was evaluated by the apparent phenomena on the relative quality evaluation parameter, the relative dynamic elastic modulus evaluation parameter, and the comprehensive damage evaluation parameter. The microstructure of corroded products was investigated through scanning electron microscopy (SEM) to reveal the deterioration mechanism. The result shows that the addition of 1% nano-CaCO₃ can enhance the resistance of concrete to sulfate corrosion, and the service life of concrete structures will increase significantly.

High-Capacity and Long-Lifespan Aqueous LiV3O8/Zn Battery Using Zn/Li Hybrid Electrolyte

Aqueous zinc-ion batteries (AZIBs) are promising candidates for large-scale energy storage because of their low cost and high safety. However, their practical applications are impeded by low energy density and short service life. Here, an aqueous Zn2+/Li+ hybrid-ion battery is fabricated using the LiV3O8 nanorods as the cathode, metallic Zn as the anode, and 3 M Zn(OTf)2 + 0.5 M LiOTf aqueous solution as the electrolyte. Compared with the batteries using pure 3 M Zn(OTf)2 electrolyte, the cycle performance of the hybrid-ion battery is significantly improved. After 4000 cycles at 5 A g1, the remaining capacity is 163.9 mA h g−1 with impressive capacity retention of 87.0%. Ex-situ XRD, ex-situ XPS, and SEM tests demonstrate that the hybrid electrolyte can inhibit the formation of the irreversible Zn3(OH)2V2O7·2H2O by-product and restrict Zn dendrite growth during cycling, thereby improving the cycle performance of the batteries.