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This paper presents an in-depth study of the variable reference process to improve the organization and properties of selective laser melting TC4 specimens. A relationship equation between body energy density and stratification is proposed. This study aimed to look into how layer and volume energy density affect the surface, tensile characteristics, and microstructure of specimens. The test findings demonstrated that specimen densities rise as the power index falls, with the most excellent density reaching 99.42%. The number of secondary α’ phases declined as the energy density of the laminae slowed down. The tensile strength of these specimens reached 1190.84 MPa, and the yield strength came at 1103.87 MPa with the same interval of variable laser power. This offers a fresh avenue for research into SLM to enhance the specimens’ overall performance.

The tensile properties and microstructure of Ti6Al4V titanium (TC4) alloy specimens fabricated by SLM under five scanning strategies were studied. They are the bidirectional scanning with a 67° rotation (R-scan) strategy, bidirectional scanning along with x-axis (X-scan) strategy, bidirectional scanning along with y-axis (Y-scan) strategy, bidirectional scanning with a 90° rotation in each layer (XY-scan) strategy, and the filled scanning strategy with homocentric squares (H-scan) strategy. Through the tensile experiments of specimens fabricated by different scanning strategies, it is found that the fabricated specimens by the XY-scan strategy show the best tensile properties. Compared with the R-scan strategy, the maximum tensile strength of the specimens prepared by the XY-scan strategy increased by 17.3%, and the maximum tensile strength reached 919.55 MPa. The tensile experiment of the fabricated specimens by the angle offset XY-scan strategy shows that the tensile property is the best when the offset angle is 45°. Compared with the XY scanning strategy, the maximum tensile strength of the specimens prepared by the angle-shifted XY scanning strategy was increased by 46.1%, and the maximum tensile strength reached 1343.27 MPa. The fracture surfaces of the specimens are mainly composed of cleavage cracks and dimple cracks. The tensile properties are the worst when the fracture cracks are mainly cleavage cracks and the tensile properties are the best when the cracks are mainly dimple cracks. When the α′-phase direction of acicular martensite inside and outside the β-phase of columnar crystal is parallel to the tensile direction, the tensile properties of specimens are improved. When the secondary α′-phase direction is parallel to the tensile direction, the tensile property is further improved.

The Betta fish displays a remarkable variety of phenotypes selected during domestication. However, the genetic basis underlying these traits remains largely unexplored. Here, we report a high-quality genome assembly and resequencing of 727 individuals representing diverse morphotypes of the Betta fish. We show that current breeds have a complex domestication history with extensive introgression with wild species. Using a genome-wide association study, we identify the genetic basis of multiple traits, including coloration patterns, the "Dumbo" phenotype with pectoral fin outgrowth, extraordinary enlargement of body size that we map to a major locus on chromosome 8, the sex determination locus that we map to

Herein, the mechanism underlying the effect of potato powder on noodle quality is investigated. The pasting, rheological, and thermal properties of dough with different contents (5%, 10%, 15%, 20%, 25%, and 30%) of potato powder and fresh noodle quality were examined. An increase in the potato powder content resulted in the deterioration of the dough pasting properties as well as noodle adhesiveness and springiness, with increases in dough loss and storage modulus. It also decreased the dough freezable water content and water activity and increased the semi-bound dough water content and noodle water absorption. In addition, a broken gluten network could be observed, which became loose with an increase in the noodle cooking loss. Furthermore, a decrease in noodle smoothness and color deterioration were observed, together with an improved taste. Acceptable noodle quality was obtained with the addition of

Roughness of abrasive air jet micromachining surface has a significant influence on electro-osmotic flow characteristics, optical properties and adhesion properties. The characterization of surface roughness based on power spectral density approach is studied. The formation mechanisms of surface topography are analyzed. The influence of process parameters on the roughness of abrasive air jet micromachining surface is discussed. The results show that surface profiles with close values of usual roughness parameters can be distinguished by power spectral density curves. The power spectral density curves can be classified into four categories based on the marked knee points on spatial frequency of 0.01 μm−1 and 0.1 μm−1 approximately. Power spectral density curve can be divided into three regions, namely, low frequency region, intermediate frequency region and high frequency region. The roughness of low frequency region and the roughness of intermediate frequency region play dominant roles in the surface roughness, while the contribution of the roughness of high frequency region is negligible. The low frequency region is associated with the overlap of craters. The intermediate frequency region is associated with the indentation removal mechanism and edge cutting mechanism. The high frequency region is associated with micro-dents removal. The roughness of low frequency region increases with an increase in air pressure, while it decreases with an increase in standoff distance. The roughness of low frequency region decreases firstly and then it increases with an increase in nozzle traverse speed. The roughness of intermediate frequency region increases firstly and then it decreases with an increase in air pressure, standoff distance and nozzle traverse speed. The Rq increases with an increase in air pressure, while it decreases with an increase in standoff distance. The Rq decreases firstly and then it increases with an increase in nozzle traverse speed.

The Betta fish displays a remarkable variety of phenotypes selected during domestication. However, the genetic basis underlying these traits remains largely unexplored. Here, we report a high-quality genome assembly and resequencing of 727 individuals representing diverse morphotypes of the Betta fish. We show that current breeds have a complex domestication history with extensive introgression with wild species. Using a genome-wide association study, we identify the genetic basis of multiple traits, including coloration patterns, the “Dumbo” phenotype with pectoral fin outgrowth, extraordinary enlargement of body size that we map to a major locus on chromosome 8, the sex determination locus that we map to dmrt1 , and the long-fin phenotype that maps to the locus containing kcnj15 . We also identify a polygenic signal related to aggression, involving multiple neural system-related genes such as esyt2 , apbb2 , and pank2 . Our study provides a resource for developing the Betta fish as a genetic model for morphological and behavioral research in vertebrates.

A comparative study was carried out on the wear of 38CrSi high-alloy steel using TiCrAlN- and TiAlN-coated tools. The presence of elemental Cr in the TiCrAlN coating resulted in formation of a Cr–O film on the tool, which provided a lower friction coefficient. This also mitigated transfer of cutting heat to the tool substrate and inhibited elemental diffusion between the tool and the workpiece. Simultaneously, the hard Cr–O film, which formed outside the Al–O film, provided excellent wear resistance and protected the Al–O film. Thus, elemental Cr played an active role in enhancing the wear resistance of the tool, prolonging its life. A workpiece cut using a TiCrAlN-coated tool had a surface roughness of 0.79 µm, which was about 62% lower than that obtained using a TiAlN-coated tool. Although wear of the TiCrAlN-coated tool was reduced, reaching 0.2 mm over the standard test time of 8 min, this time was 300% longer than that observed with the TiAlN-coated tool. Furthermore, the cutting force components were smaller, at up to 8 N, and the cutting force was 50% lower than with the TiAlN-coated tool. The wear and failure mechanisms of micro-milling 38CrSi alloy were the product of a combination of forms of wear and followed the wear law in terms of tool tip breakage, coating damage, abrasive wear, and adhesive wear; coating damage had the most important effect on tool life.

The performance and quality of SLM by using thicker layers of thickness 250 μm were investigated. The fine powder used can effectively reduce the pore area during SLM. Single-track experiments were conducted to select the optimal combination of exposure time and point distance to narrow down the process parameter windows. In multi-layer fabrication, experimental groups with higher relative densities of 99.99% were observed, and the maximum building rate reached 9 mm3/s. Auxiliary processing technology, such as surface remelting, can greatly improve surface quality and reduce surface roughness. The microstructures are mainly equiaxed crystals and columnar crystals with a ratio greater than 1. The average values of the ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) are 670 MPa, 474 MPa and 26%, respectively. Hence, the overall performance is better by using thicker layers.

We describe two new species of Parosphromenus from Indonesia based on morphological and molecular diagnoses. Parosphromenus juelinae, sp. nov., occurs on Bangka Island. Its unpaired fin coloration is similar to that of P. deissneri, but it differs from the latter in having a rounded caudal fin with a non-filamentous branched median ray and a smaller anal fin. Although the new species has the same caudal fin structure as P. bintan, it can be distinguished from the latter by its distinct unpaired fin coloration and the intense red color on the body flanks. Parosphromenus kishii, sp. nov., is found only in a single river system in Kalimantan Tengah. It is distinguished from all other congeners by the unique coloration of its caudal fin. A phylogenetic tree based on the cytochrome b (cytb) gene indicates that the two new species are distinct monophyletic groups constituting distinct phylogenetic branches from their congeners. Cytochrome b Genetic distances between Parosphromenus juelinae, sp. nov., and Parosphromenus kishii, sp. nov., and the other taxa in the phylogenetic tree range from 2.44% to 19.52% and from 8.65% to 17.28%, respectively.

Absorptive capability is the capability of actors to acquire, assimilate and exploit external knowledge. In this paper, we consider absorptive capability to be multi-dimensional and to have three dimensions. Although a sufficient amount of work in the literature discusses dynamic absorptive capability, empirical studies are relatively rare. At the urban or regional levels, related empirical studies are even fewer. In this paper, we build a framework of the dynamic absorptive capability at the urban level by using 339 Chinese cities at the prefecture level and above as our sample. In order to take the geographical distance into consideration, we use a Spatial Durbin Model to measure the effects of the acquirement, assimilation, and exploitation of absorptive capability. The results show that all of the core variables (acquirement, assimilation, and exploitation) have significant positive impacts on innovation performance. Additionally, the two control variables (R&amp, D personnel and R&amp, D investment) have significant positive impacts on innovation performance. In this way, the role performed by multidimensional absorptive capability in fostering innovation performance is highlighted, and some policy recommendations are provided.

Background The aim of this study was to evaluate the effectiveness and safety of different treatment strategies for endogenic caesarean scar pregnancy (CSP) patients. Methods According to Vial’s standard, we defined endogenic-type CSP as (1) the gestational sac growing towards the uterine cavity and (2) a greater than 0.3 cm thickness of myometrial tissue at the caesarean scar. A total of 447 endogenic CSP patients out of 527 patients from 4 medical centres in China were enrolled in this study. A total of 120 patients were treated with methotrexate (MTX) followed by surgery, 106 received ultrasound-guided curettage directly and 221 received curettage combined with hysteroscopy. The clinical information and clinical outcomes of these patients were reviewed. Successful treatment was defined as (1) no additional treatment needed, (2) no retained mass of conception and (3) serum β subunit of human chorionic gonadotropin (β-hCG) level returning to a normal level within 4 weeks. The success rate was analysed based on these factors. Result Among 447 patients, no significant difference was observed in baseline characteristics between groups except for foetal heartbeat. The success rate was significantly different (p Conclusion The combination of curettage and hysteroscopy represents the most effective strategy. Pretreatment with MTX did not result in better clinical outcomes. Ultrasound-guided curettage directly should not be considered a first-line treatment choice for endogenic CSP patients.

In this paper, the Taguchi method has been used to optimize cutting parameters in the turning of Ti6Al4V/Al7050 laminates under elliptical vibration cutting. The turning tests were conducted based on L16 orthogonal array, which was designed by the Taguchi method. The analysis of variance was used to calculate impacts of cutting parameters on cutting forces and temperature. The analysis of results showed that the vibration frequency is the dominant factor on the cutting force and the vibration amplitude is a dominant factor affecting the temperature. The analysis of variance was also used to predict the cutting force and temperature in the turning of Ti6Al4V/Al7050 laminate. A good agreement between the predicted and the actual value can be found in the results.

To investigate the forming characteristic and obtain a greater process control of the pulsed selective laser melting (P-SLM), the single melting point and single-track and multi-layer block experiments were conducted to investigate the influence of various process parameters on the forming process of P-SLM. A rapid method for the optimization of parameters based on molten pool characterizations is developed. Furthermore, the relationships between the two key process parameters (exposure time, point distance) and the geometric characteristics of single tracks are investigated by linear regression analysis. The research on the surface morphology and the overlapping rate of single-track experiments shows that the value of P-SLM scanning speed is determined by the diameter of single melting point. With relatively high forming efficiency, the highest value of density can be up to 99.99% when the process parameter of exposure time is 80 μs, the point distance is 48 μm, and the hatch space is 80 μm. The yield strength, tensile strength, and elongation of the best sample are 533 Mpa, 647 Mpa, and 40%, respectively, which are higher than that of 316L stainless steel forgings standard (ASTM A473-13).

The collaboration of scientists is important for promoting the scientific development and technological progress of a country, and even of the world. Based on the cooperation data of academicians of the Chinese Academy of Sciences (CAS) in the China National Knowledge Infrastructure (CNKI), we portray the scientific cooperation network of Chinese scientists using Pajek, Gephi, ArcGIS, and other software, and the complexity of the scientific cooperation network of Chinese scientists and its proximity mechanism are explored by combining complex network analysis, spatial statistical analysis, and negative binomial regression models. Our main conclusions are as follows: (1) In terms of network structure, the scientific cooperation network of Chinese scientists has a multi-triangular skeleton, with Beijing as its apex. The network has an obvious hierarchical structure. Beijing and Shanghai are located in the core area, and 16 cities are located in the semi-periphery of the network, while other cities are located at the periphery of the network. (2) In terms of spatial distribution, the regional imbalance of the scientific cooperation of Chinese scientists is obvious. Beijing–Tianjin–Hebei, the Yangtze River Delta, and the central-south region of Liaoning are hot spots for the scientific research activities of Chinese scientists. (3) The negative binomial regression model accurately explains the proximity mechanism of the scientific cooperation network of Chinese scientists. The geographical proximity positively affects the scientific cooperation of Chinese scientists under certain conditions. The educational proximity is the primary consideration for scientists to cooperate in scientific research. The closer the educational level of the cities, the greater the cooperation. Economic and social proximity can promote scientific cooperation among scientists, whereas institutional proximity negatively and significantly affects scientific cooperation.

Scientists are a core element of regional technological innovation and economic growth. Academicians of the Chinese Academy of Sciences (CAS) and Chinese Academy of Engineering (CAE) are outstanding representatives of Chinese scientists. The purpose of this paper is to reveal the characteristics of Chinese scientists&rsquo, space migration, depict the structural topology of their flow network and to analyze the driving mechanisms behind the characteristics of their space migration. We mainly used spatial statistics, complex network analysis, and a modified location quotient. Our main conclusions are as follows: (1) The spatial distribution of Chinese scientists at different development stages tends to converge. The Chinese scientists&rsquo, birthplaces are highly concentrated in the eastern coastal areas and the Yangtze River basin. Education locations are highly consistent, with clusters of global high-level educational resources at home and abroad, and their workplaces are mainly distributed in economically developed cities. (2) In terms of network characteristics, the spatial heterogeneity of the growth of Chinese scientists is obvious. Only a few cities, such as Beijing, Shanghai, and Nanjing, have higher degrees of node centrality, strength centrality, and betweenness centrality, so their networks&rsquo, hierarchical structures are pyramid-shaped and their core-periphery structures are prominent. By identifying the roles of the cities as network nodes, we found that only Beijing plays accomplished and stable roles, whereas other cities play a single role. (3) Regarding driving mechanisms, Chinese scientists&rsquo, spatial migration has been influenced by national policy, regional economic level, education level, and individual traits at national, regional, and personal scales. Therefore, the combined effects of various forces have driven the evolution of the flow network of Chinese scientists.

In this study, the layer thickness in the Selective Laser Melting (SLM) process was increased to 200 µm to solve the problem of the low build rate of SLM. And adopted the heat treatment process to improve the mechanical properties of specimens. The single-tracks and multi-layer fabrication experiments of the aerosolized 316L stainless steel powder were carried out by using 400 W laser power. The process parameters were optimized by analyzing the density, the microstructure, the tensile properties and the defect mechanism of the molded parts. The experiment results showed that when the exposure time was 120–160 μs and the overlap rate was 30–50%, the relative densities of the samples could be higher, up to 99.99%. The un-melted defects, the balling defects, and the micropore defects were observed in the SLM process. Un-melted defects can be avoided by adjusting the distance between the points and the hatch spacing. Balling included large balling and spatter balling. The large balling can be completely avoided by adjusting the process parameters. The spatter balling was divided into droplet spatter and powder spatter, which cannot be completely eradicated but can be inhibited by decreasing the exposure time. The build rate can be enhanced to 12.4 mm3/s. By the heat treatment process, the yield strength, the tensile strength and the elongation of the sample can reach 665 MPa, 718 MPa, and 35%, respectively.

The selection of anesthetic method and drugs is of utmost importance for patients undergoing caesarean section. The application of anesthetic drugs may affect the immune system of the maternal patient and neonate. Therefore, the present study aimed to analyze the effect of dexmedetomidine combined with lumbar anesthesia on type 1 T-helper cells (Th1) and Th2 cytokines in mothers and their neonates undergoing caesarean section. A total of 60 females with full-term pregnancies and an American Society of Anesthesiologists grade I or II who received caesarean section were selected and equally divided in a randomized manner into a control group receiving lumbar epidural anesthesia and a combination group treated by dexmedetomidine combined with lumbar epidural anesthesia. The visual analogue scale (VAS) score, adverse reactions, traction response and the neonates' Apgar score were compared between the two groups. The levels of interleukin-2 (IL-2), tumor necrosis factor-α (TNF-α), IL-4 and IL-10 in the blood of mothers and neonates were detected by reverse transcription-quantitative PCR and ELISA. The results indicated no statistically significant difference in the Apgar score between the two groups. The VAS scores, adverse reactions, reduced traction response, as well as IL-2 and TNF-α expression, in the mothers of the combination group were significantly decreased, while IL-4 and IL-10 were obviously elevated compared with those in the controls (P

A 400 W high-power laser was used to fabricate 200-&micro, m-thick Ti-6Al-4V samples to evaluate the effects of small (50 &mu, m) and large (200 &mu, m) beam diameter on density, microstructure and mechanical properties. A series of single-track experiments demonstrated that it was challenging for the small-beam laser to fabricate smooth and defect-free scan tracks. A larger beam diameter efficiently avoided process instability and provided a more stable and uniform melt pool. By increasing the beam diameter, the density of multilayer samples reached 99.95% of the theoretical value, which is much higher than that achieved with the small beam diameter. However, it was difficult to completely eliminate defects due to serious spatter and evaporation. Moreover, all of the generated samples had relatively coarse surfaces. For the large beam diameter of 200 &micro, m, the optimal yield strength, ultimate tensile strength and elongation were 1150 MPa, 1200 MPa and 8.02%, respectively. In comparison, the small beam diameter of 50 &micro, m resulted in values of 1035 MPa, 1100 MPa and 5.91%, respectively. Overall, the large-diameter laser is more suitable for high-power selective laser melting (SLM) technology, especially for thick layers.

The effect of specific alloy elements on adiabatic shearing sensitivity was studied by cutting experiment for the industrial pure titanium (TA2) and titanium alloy (Ti-6Al-4V) in the level of valence electron structure (VES). The valence electron structure (VES) parameters that affect adiabatic shearing sensitivity were studied in this paper. The results show the electron density of heterophase boundary and the lattice electron density are related to adiabatic shearing sensitivity. The higher the electron density of heterophase boundary, the lower the lattice electron density, the higher adiabatic shearing sensitivity, and the easier the formation of the serrated chips. The electron density of heterophase boundary and the lattice electron density have coupling effect on adiabatic shearing sensitivity. The adding of Al and V elements for Ti-6Al-4V can increase the electron density of heterophase boundary and reduce the lattice electron density, so its adiabatic shearing sensitivity is higher than that of TA2, which would produce easily serrated chips divided evenly by the adiabatic shear band (ASB) and enlarge the degree of serration to exacerbate the tool vibration.

Selective laser melting (SLM) is a potential additive manufacturing (AM) technology. However, the application of SLM was confined due to low efficiency. To improve efficiency, SLM fabrication with a high layer thickness and fine powder was systematically researched, and the void areas and hollow powders can be reduced by using fine powder. Single-track experiments were used to narrow down process parameter windows. Multi-layer fabrication relative density can be reached 99.99% at the exposure time-point distance-hatch space of 120 μs-40 μm-240 μm. Also, the building rate can be up to 12 mm3/s, which is about 3–10 times higher than the previous studies. Three typical defects were found by studying deeply, including the un-melted defect between the molten pools, the micro-pore defect within the molten pool, and the irregular distribution of the splashing phenomenon. Moreover, the microstructure is mostly equiaxed crystals and a small amount of columnar crystals. The averages of ultimate tensile strength, yield strength, and elongation are 625 MPa, 525 MPa, and 39.9%, respectively. As exposure time increased from 80 μs to 200 μs, the grain size is gradually grown up from 0.98 μm to 2.23 μm, the grain aspect ratio is close to 1, and the tensile properties are shown as a downward trend. The tensile properties of high layer thickness fabricated are not significantly different than those with a coarse-powder layer thickness of low in previous research.

To improve the precision of the nonhorizontal suspension structure and the forming quality of the overhanging surface by selective laser melting, the influence of laser power on the upper surface and the overhanging surface forming quality of 316L stainless steel at different forming angles was studied in the experiment. The influence of different scanning strategies, upper surface remelting optimization, and overhang boundary scanning optimization on the formation of overhanging structures was compared and analyzed. The forming effect of chromium&ndash, nickel alloy is better than 316L stainless steel below the limit forming angle in the overhanging structure. The better forming effect of chromium&ndash, nickel alloy can be obtained by narrowing the hatch space with the boundary optimization process. The experiment results show that the forming of the overhanging structure below the limit forming angle should adopt the chessboard scanning strategy. The smaller laser power remelting is beneficial to both the forming of the overhanging surface and the quality of upper surface forming. The minimum value of surface roughness using the 110 W power laser twice during surface remelting and boundary scanning 75&deg, overhanging surface can reach 11.9 &mu, m and 31.1&mu, m, respectively. The forming accuracy error range above the limit forming angle is controlled within 0.4 mm, and the forming quality is better. A boundary count scanning strategy was applied to this study to obtain lower overhanging surface roughness values. This research proposes a process optimization and improvement method for the nonhorizontal suspension structure formed by selective laser melting, which provides the process support for practical application.