Results Of Resistance Tests Research Articles

Fulvic and alginic acid separation during pressure retarded osmosis: Governing effects and fouling mechanisms

In this study, the performance of model foulant (alginate and fulvic acid) separation by pressure retarded osmosis (PRO) was systematically studied. At the various operating conditions tested, fulvic acid had a greater flux decline and power density loss than alginate. The results of membrane resistance test, SEM-EDX images, and the solute diffusion coefficient K demonstrated that fulvic acid was more likely to clog the inside of the porous support layer of the PRO membrane, which would exacerbate the internal concentration polarization (ICP) phenomena. Although model foulants were successfully removed by PRO (with a retention rate of about 95.0%), the presence of either calcium or magnesium ions was detrimental to the fouling process of PRO membranes. According to the XDLVO theory analysis results, the presence of calcium or magnesium ions increased foulant adhesion to the PRO membrane, thereby resulting in membrane fouling. In addition, Pearson correlation coefficient also showed that the hydrodynamic conditions (effective osmotic pressure difference as well as operating hydraulic pressure acting vertically to the membrane and parallel to the membrane cross-flow shear force) had an important effect on the degree of membrane fouling. This is attributed to the influence of the hydrodynamic conditions on the initial influence water flux and thus on the fouling of the PRO membrane.

POTENSI AMPAS KELAPA (Cocos nucifera L.) SEBAGAI ALTERNATIF BAHAN PEMBUATAN KERTAS KOMPOSIT

Coconut dregs is a waste that has non-wood fiber thus it is potential as a material for making composite paper. The use of coconut dregs in this study aims to determine its potential as a raw material for making composite paper through tensile resistance and tear resistance.
 The making of composite paper in this study was carried out by combining coconut pulp and used HVS paper pulp. The design used was a completely randomized design (CRD) with 3 replications consisting of 3 treatments and a control. The data obtained were analyzed using the Anova test and the DMRT test with a level of 5%..
 The highest paper tensile resistance test results were obtained by P1 which was 0.26 kN / m smaller than 1.26 kN / m (P0 as a control), as well as the highest paper tear resistance test results obtained by P2 at 340 mN smaller than 666 , 4 mN (P0 as control). Based on the data obtained, the addition of coconut dregs or not in making composite paper shows a potential that does not have a significant effect. This research has the potential to be developed for better paper quality.

Identification of Shewanella putrefaciens as a novel pathogen of the largemouth bass (Micropterus salmoides) and histopathological analysis of diseased fish.

The largemouth bass (Micropterus salmoides) is an economically important aquaculture species in China, and its production has increased rapidly in recent years. Although Shewanella putrefaciens is known to infect several fish species, its role in infecting M. salmoides is relatively unknown. Here, we isolated a gram-negative bacterial strain (termed XX2021) from farmed largemouth bass. Based on the results of 16S rRNA sequencing and phylogenetic analyses, the isolate was identified as S. putrefaciens. The virulence of XX2021 was dependent on water temperature, such as the LD50 values were 4.21×104, 7.26×105, and 2.47×106 CFU/g fish weight at 10°C, 18°C, and 25°C, respectively. Four virulent genes-including dksA, hem, lonR, and fur-were screened through a PCR assay. The results of an antibiotic resistance test showed that XX2021 was sensitive to kanamycin, cefotaxime, doxycycline, sulfamethoxazole, florfenicol, tetracycline, and gentamicin; showed intermediate susceptibility to streptomycin, ampicillin, and norfloxacin; and was resistant to nalidixic acid and penicillin. XX2021-infected fish showed clinical symptoms typical of S. putrefaciens infection. In addition, we re-isolated XX2021 from infected fish and confirmed its identity using 16S rRNA sequencing. Histopathological changes were observed in the intestine, head kidney, spleen, and liver of diseased fish. This study presents the first report of the pathogenic effects of S. putrefaciens in farmed largemouth bass. Our findings may help develop effective disease control strategies for aquaculture fish and prevent disease outbreaks under low water temperatures.

Epidemiology and surveillance implications of community-acquired pneumonia in children.

Community-acquired pneumonia (CAP) is the single largest infectious cause of hospitalization and death in children worldwide. With improved immunizations, the incidence of bacterial pneumonia and the number of colonized bacteria have decreased. However, respiratory viruses are still an important cause of CAP, especially as new infectious agents such severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) emerge. The SARS-CoV-2 virus emerged in 2019 and caused the current coronavirus disease 2019 pandemic. Therefore, it is necessary to elucidate the epidemiology and causative pathogens of CAP. Recently, the Pneumonia and Respiratory Disease Study Group, affiliated with the Korean Academy of Pediatric Allergy and Respiratory Disease, investigated the causative pathogens of respiratory infections in children hospitalized with CAP, the serotype of Streptococcus pneumoniae, and the prevalence of Mycoplasma pneumoniae with gene mutations. Antibiotic resistance and serotype test results can determine the use of empirical antibiotics. Moreover, it is possible to help develop future vaccines by comparing bacterial culture results with vaccine serotype and identifying the changes and prevalence of each serotype. Therefore, we will perform continuous national surveillance and monitor the epidemiology of respiratory pathogens in Korea and worldwide. The surveillance of these respiratory infections can play a role in monitoring the emergence of new infectious diseases such as SARS-CoV-2.

Preparation and properties of α-Al2O3 diffusion barrier on stainless steel 316

A compact and adherent Al2O3 diffusion barrier was obtained between a Ni coating and stainless steel 316 (316SS) through double-pulse composite plating coupled with in-situ thermal growth. To promote the formation of α-Al2O3 at low temperature, a Cr2O3 film was firstly prepared by pre-oxidation of 316SS. Then a Ni-Al/NiO composite coating was deposited on 316SS in a modified Watts’ bath with a Zeta potential of about +21.89 mV, a favorable condition for the co-deposition of double particles and nickel, followed by heat treatment in Ar at 800 ℃ for 12 h. Results of diffusion resistance tests at 750 and 800 ℃ for 100 h in Ar suggest that the Ni/α-Al2O3 composite coating changes slightly during the annealing treatment and significantly prevents the diffusion of Fe and Cr from 316SS substrate to the upper Ni layer. Furthermore, corrosion resistance of the composite coating is higher than that of the 316SS/Ni sample.

Fire Resistance of an Assembled Integrated Enclosure Panel System

Due to increasing economic development in recent years, large-scale prefabricated structures have been used for substations. However, the assembly of steel structures suffers from technical problems, such as the mismatch between the fire protection level of the main structure and the enclosure system. This paper proposes an assembled integrated enclosure panel system for covering and fireproofing steel structures, such as beams and columns, consisting of sandwich wall panels and autoclaved lightweight concrete (ALC) wall panels covering the main steel structure. Fire resistance tests were carried out for each part and the entire integrated enclosure panel system to fully investigate its fire resistance performance. ALC and gypsum were selected as the external fire protection materials for the sandwich wall panel test for theoretical analysis and fire resistance test. The fire resistance test results show that the designed solutions of sandwich wall panels and ALC panels covering steel beams and columns meet the fire protection requirements of the ISO-834 standard fire test. The proposed size scheme of the integrated enclosure panel system is an integrated sandwich wall panel composed of 50 mm thick ALC board + 50 mm thick rock wool layer + 50 mm thick ALC board and the integrated structure of 100 mm thick ALC board covering beams and columns. The designed U-shaped connectors between the wall panels are suitable for the assembled integrated enclosure panel system.

The association between daily beverage consumption and risk of chronic disease among adult women in Turkey

Introduction: It has been shown that the contribution of beverage energy to total energy intake may increase the risk of diseases in various countries. The aim of this study is to evaluate the relationship between the consumption of added sugar from beverages and nutritional status, anthropometric measurements and biochemical blood parameters in adults.
 Materials and Methods: This study was designed as an analytical and cross-sectional study and conducted on 100 adult females aged 18-65 who applied to the private diet outpatient clinic in Istanbul/Turkey between November 2020 and April 2021. The demographic characteristics of the individuals were applied to the participants using the food frequency questionnaire, eating habits, physical activity habits and beverage consumption frequency questionnaires.
 Results: The mean age of the women in the study was 31.8 years . Total energy intake from beverages in women over 25 years old was found to be 145.3 kcal and significantly lower. All women in the study consumed tea and coffee. The consumption rate of all beverages except energy drinks was found to be higher in the younger adults. A positive correlation was found between the results of an insulin resistance test and the total amount of added sugar from the beverages consumed (r=0.297 p=0.043). 
 Conclusions: Lower levels of consumption of sugar-sweetened beverages may result in a lower burden of chronic diseases. Future studies should explore consumption patterns of added sugar beverages and individual-level associations with such consumption.

Abrasive wear resistance of matrix composites carbon fiber reinforced polymers

The paper presents the results of the abrasive wear resistance test of composites based on polymers reinforced with carbon fibers. Two types of fiber composites obtained from a yacht manufacturer were used for the tests. The tests were carried out using the ball-cratering method without abrasive suspension. On the basis of the specific wear rate Kc, better tribological properties of the polyester matrix reinforced with glass fabric were observed compared to the polyester matrix reinforced with a glass emulsion mat. The composite material reinforced with glass cloth was characterized by smaller crater diameters, which may cause plastic deformation due to the low hardness of the material.

Fire behaviour of GFRP-reinforced concrete slab strips. Effect of straight and 90° bent tension lap splices

This paper presents results of fire resistance tests on concrete slab strips reinforced with ribbed glass fibre reinforced polymer (GFRP) bars, comprising continuous reinforcement or tension lap splices with different geometries (straight- and 90° bent-ends), overlap lengths and bar types. The type of reinforcement (material and surface finish), the rebar diameter and the concrete cover thickness were also assessed. It was shown that GFRP-reinforced concrete slabs with continuous reinforcement can endure over 180 min of fire exposure with considerably lower concrete covers than those currently recommended in design codes, provided that the rebars remain well-anchored in cool zones of the member. Slabs with straight-end splices failed due to debonding of the overlapped rebars after 19 to 39 min of fire exposure, depending on the type of bar and splice length. With 90° bent-end splices, the fire resistance significantly increased, up to 75 min, as they allowed anchoring the reinforcement in a cooler zone of the slab where bond was less degraded.

Recycling of granite powder and waste marble produced from stone processing for the preparation of architectural glass–ceramic

• Glass-ceramic was prepared using granite powder and waste marble by melting-sintering method. • The addition of MgO changes the main crystalline phase of the glass–ceramic from wollastonite to augite. • The acid resistance of glass-ceramics is weakened with the increase of basic oxide content in the chemical composition. • The glass–ceramic with flexural strength of 146.95 MPa and Vickers hardness of 10.24 GPa can be achieved. A large amount of solid waste is generated during the stone processing, and a serious environmental issues has arisen from the accumulation of these wastes. In this work, granite powder and waste marble are used to prepare architectural glass–ceramic. The mechanical properties, microstructure, and acid resistance of glass-ceramics designed with different compositions were investigated. With the increase of waste marble content, the main crystalline phase of glass–ceramic changed from anorthite to wollastonite, and the flexural strength of glass–ceramic was also enhanced. When the mass ratio of granite powder to waste marble is 40:60, a CaO-Al 2 O 3 -SiO 2 (CAS) glass–ceramic with a flexural strength of 109.33 MPa and a Vickers hardness of 6.61 GPa is obtained. After the addition of MgO, the main crystalline phase of the glass–ceramic is augite. Under the addition of 5 wt% MgO, the flexural strength and Vickers hardness of CaO-MgO-Al 2 O 3 -SiO 2 (CMAS) glass–ceramic reached the maximum, which are 146.95 MPa and 10.24 GPa, respectively. The mechanical properties of these two types of glass-ceramics developed from granite powder and waste marble can meet the requirements of building materials. From the acid resistance test results, it was found that the higher the content of MgO and CaO in the chemical composition of glass–ceramic, the worse the acid resistance. Therefore, the basic oxide content should be carefully controlled in the composition design of glass–ceramic. This technology of converting granite powder and waste marble into value-added glass–ceramic provides a promising method for the utilization of solid waste from stone processing, which can greatly improve the sustainability of the stone industry.

The chloroplast genome of Salix floderusii and characterization of chloroplast regulatory elements.

Salix floderusii is a rare alpine tree species in the Salix genus. Unfortunately, no extensive germplasm identification, molecular phylogeny, and chloroplast genomics of this plant have been conducted. We sequenced the chloroplast (cp) genome of S. floderusii for the first time using second-generation sequencing technology. The cp genome was 155,540 bp long, including a large single-copy region (LSC, 84,401 bp), a small single-copy region (SSC, 16,221 bp), and inverted repeat regions (IR, 54,918 bp). A total of 131 genes were identified, including 86 protein genes, 37 tRNA genes, and 8 rRNA genes. The S. floderusii cp genome contains 1 complement repeat, 24 forward repeats, 17 palindromic repeats, and 7 reverse repeats. Analysis of the IR borders showed that the IRa and IRb regions of S. floderusii and Salix caprea were shorter than those of Salix cinerea, which may affect plastome evolution. Furthermore, four highly variable regions were found, including the rpl22 coding region, psbM/trnD-GUC non-coding region, petA/psbJ non-coding region, and ycf1 coding region. These high variable regions can be used as candidate molecular markers and as a reference for identifying future Salix species. In addition, phylogenetic analysis indicated that the cp genome of S. floderusii is sister to Salix cupularis and belongs to the Subgenus Vetrix. Genes (Sf-trnI, Sf-PpsbA, aadA, Sf-TpsbA, Sf-trnA) obtained via cloning were inserted into the pBluescript II SK (+) to yield the cp expression vectors, which harbored the selectable marker gene aadA. The results of a spectinomycin resistance test indicated that the cp expression vector had been successfully constructed. Moreover, the aadA gene was efficiently expressed under the regulation of predicted regulatory elements. The present study provides a solid foundation for establishing subsequent S. floderusii cp transformation systems and developing strategies for the genetic improvement of S. floderusii.

Comparison between Electrical Resistivity Tomography and Geotechnical Field Data for Characterizing Soil Profiles

Background: Electrical resistivity tests at a project site could be a valuable economical alternative to typical geotechnical soil exploration and a reliable source of data. In the present study, the soil at a constructed underground water tank site in Qassim Region – Saudi Arabia is investigated using the electrical resistivity testing method. Objective: The study aims to compare the results of traditional soil boreholes that were conducted at various stages of the project lifetime with the interpretation of soil resistivity test results. Methods: Eight soil boreholes were drilled at the water tank site to capture the nature of soil layers. The electrical resistivity of soil layers at the site is measured and used to investigate the ground subsurface of the project site. The geophysical software, ZondRes2d is utilized to analyze and interpret the collected data. Results: Both geotechnical soil boreholes and geophysical electrical resistivity tests revealed similar soil profiles with three main layers comprising of backfill material, clay with expansive nature, and weathered limestone and marl. The results of the electrical resistivity tests are also affirmative of available resistance values of different soils in the literature. Conclusion: The study shows that electrical resistivity testing is reliable in capturing the soil nature which presents an attractive tool for preliminary investigation of the soil-related problems of distressed structures.

Ballistic Resistance of Steel with the Structure of a Natural Ferrite-Martensitic Composite

Introduction. For steel armor materials, it is important to reduce the thickness and, consequently, the metal consumption of the protective structure. The previously developed class of materials with the structure of a natural ferrite-martensite composite (NFMC) has characteristics that favor the inhibition of crack development under impact loads and has prospects as an armor material.Problem Statement. The purpose of this work is to evaluate the possibility of using NFMC materials for armor protection devices based on the results of ballistic resistance tests under a high-power concentrated impact (a projectile flying at a hyper-high speed).Theoretical Part. The study of ballistic resistance was carried out on samples of steel 14G2 processed according to various modes. The samples had the shape of plates and a square grid on the surface. Simulation tests of the impact of heat-strengthened dowels from a powder-actuated tool and firing of military small arms at the testing site from an SVD sniper rifle and an AK-74 assault rifle with machine loading ammunition were carried out. The results of simulation tests showed a clear advantage of steel with the NFMC structure. The comparison of the results of firing with military small arms has showed that the ballistic resistance of steel with the NFMC structure depends on the ratio of the volume fractions of ferrite and martensite, which cause different thicknesses of the ductile and strong components of the composite. The highest resistance was observed for a sample with an NFMC structure processed according to the regime: quenching 730°C and tempering 180°C.Conclusions. Steels treated for the NFMC structure can provide effective protection for military personnel with a lower material consumption of armor protection devices, which is due to a special method of braking destruction during a high-power local impact. Thus, the practical application of the developed class of natural composite materials seems promising for obtaining an armor plate with a thinner thickness, which helps to reduce the weight of combat vehicles, increase their mobility and reduce fuel consumption.

HIV DNA Sequencing to Detect Archived Antiretroviral Drug Resistance.

Proviral HIV DNA integrated within CD4 T-cells maintains an archive of viral variants that replicate during the course of the infection, including variants with reduced drug susceptibility. We considered studies that investigated archived drug resistance, with a focus on virologically suppressed patients and highlighted interpretative caveats and gaps in knowledge. Either Sanger or deep sequencing can be used to investigate resistance-associated mutations (RAMs) in HIV DNA recovered from peripheral blood. Neither technique is free of limitations. Furthermore, evidence regarding the establishment, maintenance, expression and clinical significance of archived drug-resistant variants is conflicting. This in part reflects the complexity of the HIV proviral landscape and its dynamics during therapy. Clinically, detection of RAMs in cellular HIV DNA has a variable impact on treatment outcomes, modulated by the drugs affected, treatment duration and additional determinants of virological failure, including those leading to suboptimal drug exposure. Sequencing cellular HIV DNA can provide helpful complementary information in treatment-experienced patients with suppressed plasma HIV RNA who require a change of regimen. However, care should be taken when interpreting the results. Presence of RAMs is not necessarily a barrier to treatment success. Conversely, even the most sensitive sequencing techniques will fail to provide a comprehensive view of the HIV DNA archive. To inform treatment decisions appropriately, the overall clinical and treatment history of a patient must always be considered alongside the results of resistance testing. Prospective controlled studies are needed to validate the utility of drug resistance testing using cellular HIV DNA.

The L-Type Lectin-like Receptor Kinase Gene TaLecRK-IV.1 Regulates the Plant Height in Wheat.

Dwarfing is important for the production of wheat (Triticumaestivum L.). In model plants, receptor-like kinases have been implicated in signal transduction, immunity, and development. However, functional roles of lectin receptor-like kinases in wheat are poorly understood. In this study, we identified an L-type lectin receptor-like kinase gene in wheat, designated as TaLecRK-IV.1, and revealed its role in plant height. Real time quantitative PCR analyses indicated that TaLecRK-IV.1 transcript level was lower in a dwarf wheat line harboring the Rht-D1b gene compared to its transcript level detected in a taller wheat line CI12633. Importantly, the virus-induced gene silencing results showed that silencing of TaLecRK-IV.1 in the wheat line CI12633 led to dwarf plants. The results of the disease resistance test performed after the gene silencing experiment suggest no significant role of TaLecRK-IV.1 in the resistance reaction of wheat line CI12633 to sharp eyespot. Gene expression analysis revealed that the transcript abundance of TaLecRK-IV.1 was more up-regulated after the exogenous application of gibberellic acid and auxin, two development-related phytohormones, compared to the gene transcript levels detected in the control plants (mock treatment). These findings support the potential implication of TaLecRK-IV.1 in the pathway controlling plant height rather than the disease resistance role, and suggest that TaLecRK-IV.1 may be a positive regulator of plant height through the gibberellic acid and auxin-signaling pathways.

Investigation of the influence of high molecular weight polyethylene and basalt content used in three-dimensional weft-knitted fabrics on the mechanical risks

This study investigates the resistance of three-dimensional (3D) weft-knitted fabrics to mechanical risks in order to determine the impact of the percentage content of raw materials in the knits on mechanical loads. For this purpose, 3D weft-knitted fabrics, consisting of a front side, binding, and back side layers, were designed and produced on an E20 circular weft-knitting machine using organic multifilament yarns (high molecular weight polyethylene, HMWPE) and inorganic multifilament (basalt, BS) yarns for the front and back side layers and conventional polyamide yarns for the binding layer. The cut, puncture, abrasion, and tear resistance tests were performed to assess the resistance of 3D weft-knitted fabrics to mechanical risks. According to the testing results, basalt in the structure of 3D weft-knitted fabrics significantly increases the cut resistance, even in cases of a small basalt content in the knit. The puncture, abrasion, and tear resistance testing results showed that the highest HMWPE percentage content in the knitted structure provided the highest resistance to these risks, while increasing the basalt content in the knit did not improve the resistance testing results. Based on the testing results and the assessment of the protection levels provided by the knitted fabrics, the conclusion can be made that the use of HMWPE multifilament yarns and basalt multifilament yarns in the structure of 3D weft-knitted fabrics contributes to the achievement of the highest levels of performance. All the designed 3D weft-knitted fabrics provide complex protection against different mechanical risks (cut, puncture, abrasion, tear). The tests performed may be useful for further development of knitted fabrics designed to provide protection against mechanical risks.

FACTORS OF CARIES DEVELOPMENT AND WAYS TO REDUCE THEI IMPACT IN SCHOOL CHILDREN

Topic relevance. Dental diseases in children, particularly dental caries, are still requiring approaches and methods of their effective prevention and treatment. Analysis of caries rates in 7 – 9 year children has revealed a probable increase in the prevalence and intensity of caries in permanent teeth over the past 20 years.
 The aim of the study. Epidemiological studies indicate that the intensity of dental caries among children and adolescents in Ukraine varies from 2 to 5.8 depending on the region of residence. We conducted dental clinical-laboratory examination and performed a questionnaire survey of 223 schoolchildren and their parents in order to determine the main factors of caries occurrence and possibility to influence them.
 Materials and methods. The statistical significance of the differences between the results obtained for different data groups with normal distribution was determined using Student's t-test. The correlation coefficient was considered significant when the error probability was p<0.05.
 Results and discussion. The results of the study revealed the greatest increase in the prevalence and intensity of caries in permanent teeth in 7-8 year old children (by 17.3% and 2.4 times respectively) and in 910 year old children (by 21.5% and 2.5 times, respectively). The course of caries in children aged from 7 to 12 occurs against the background of the decrease of pH value and microcrystallization of the oral liquid and is caused by the lowering teeth resistance to caries that is supported by the results of the enamel acid resistance test. In order to reduce the prevalence and intensity of dental caries in children, there is an urgent need to elaborate a proper approach to preventive measures aimed at enhancing the resistance of hard dental tissues. The developed scheme of preventive activities with children is based on regular dental checkups, fostering skills of proper tooth brushing and oral care, providing basic information about caries development and health consequences when it left untreated, options of caries treatment and the basics of good nutrition.
 Conclusion. Taking control of caries factors will contribute to the strengthening healthy dental tissues and creating favourable conditions for healthy functioning of teeth that will result in the strengthening of oral and general health in children. The application of the elaborated schemes of prognostic assessment of cariesogenic situation and caries prevention measures for children and their parents will reduce the dental caries rates.

Status Resistensi dan Keberadaan Virus Dengue pada Nyamuk Aedes Sp di Kelurahan Pinang Kencana, Kota Tanjungpinang, Kepulauan Riau

Tanjungpinang Timur Village is an endemic area, and every year there is a death rate due to dengue fever. This study aimed to map the resistance and presence of the dengue virus in Aedes sp mosquitoes in Pinang Kencana Village. This research was observational with a descriptive approach. The samples were mosquitoes bred in the Vector Laboratory of Poltekkes, Ministry of Health, Tanjungpinang, from eggs trapped in ovitraps distributed in the study area. A total of 78 ovitraps were placed inside the house, 45 were positive, while 45 positive ovitraps were placed outside the house out of a total of 84 ovitraps. Ovitrap index numbers outside (57.7%) and inside the house (53.6%) with an overall ovitrap index of 55.6%. The resistance test results using the CDC bottle bioassay method showed that Aedes sp mosquitoes from Pinang Kencana Village were resistant to the pesticide deltamethrin dose of 10 g/bottle with a diagnosis time of 30 minutes with a mosquito mortality percentage of 68.33%. The PCR results for dengue virus in the sample mosquitoes showed no presence of dengue virus in the mosquito samples, both DEN-1, DEN-2, DEN-3, and DEN-4 serotypes.

Effect of Thickness and Bonding Technique on Fatigue and Fracture Resistance of Feldspathic Ultra-Thin Laminate Veneers.

To evaluate the fatigue and fracture resistance of ultra-thin laminate veneers (UTLV) with two different thicknesses and two different bonding protocols. A total of 64 flat enamel surfaces were assigned to either 0.2 or 0.4 mm UTLV. The UTLV were further subdivided and assigned to one of two bonding techniques: adhesive resin cement(RC( or preheated restorative resin composite (HC) (n = 16). Eight samples were fatigued with 750,000 mechanical cycles and 8,000 thermal cycles between 5 and 55°C in a chewing simulator, and the failure mode was evaluated using a stereomicroscope and SEM. The other eight samples from each group were loaded to failure in a universal testing machine to test the fracture resistance. Fisher's exact Probability test was used to analyze the fatigue test results, and two-way analysis of variance and Bonferroni's test were used to analyze the fracture resistance test results. The difference in fatigue resistance between failure proportions in different groups was statistically different (p < 0.05). The 0.4-mm-thick UTLV had similar results regardless of the bonding technique, while 0.2-mm-thick UTLV only showed comparable results when cemented with preheated HC. No statistically significant difference was found in fracture resistance between the tested groups (p > 0.05). The Bonding technique and the thickness of the UTLV had impacted fatigue resistance but had no significant effect on the fracture resistance. bonding of UTLV with preheated composite increases their fatigue resistance. Different testing approaches delivered different results.

Multi-Scale Structure and Directional Hydrophobicity of Titanium Alloy Surface Using Electrical Discharge.

Titanium alloys with special macro-micro composite structures of directional hydrophobicity are difficult to prepare due to poor thermal conductivity and good corrosion resistance, inhibiting the wide engineering applications for aerospace, marine engineering, and biomedicine. To prepare macro-micro composite structures on the surface of titanium alloys and achieve directional hydrophobicity, the sub-millimeter structures with an edge width of 150 μm, a groove width of 250 μm, and a depth of 250 μm were fabricated on the titanium alloy by wire electrical discharge machining (WEDM) technology, and high voltage-induced weak electric arc machining (HV-μEAM) was used to fabricate micro-scale feature size micro-structures on the processed macro-structure edges. The influence of process parameters on the morphology of microstructures was studied experimentally. The smooth surface of the titanium alloy is isotropically hydrophilic, and its contact angle is 68°. After processing the macrostructure on the titanium alloy surface, it shows directional hydrophobicity after being modified by low surface energy materials. The macro-micro composite structure formed by HV-μEAM realizes a directional hydrophobic surface with contact angles (CA) of 140° (parallel direction) and 130° (perpendicular direction), respectively. This surface has been modified with low surface energy to achieve contact angles of 154° and 143°. The results of the abrasion resistance test show that under the load of 100 g, it retains directional hydrophobicity at a friction distance of 700 mm with 600# sandpaper. The existence of the sub-millimeter macrostructure is the reason for the directionality of surface hydrophobicity. The microstructure can realize the transformation of the titanium alloy surface from hydrophilic to hydrophobic. Under the combined effects of the macro and micro composite structure, the surface of the titanium alloy shows obvious directional hydrophobicity.