Compared to conventional high temperature processes, e.g. arc additive manufacturing, thermal spraying and laser/electron-beam cladding/additive manufacturing, coatings of Ti and its alloys with cold ...spraying (CS) are increasingly attracting attention from researchers and industries, because of the low temperature and high velocity characteristics of sprayed particles, which strictly restrict the oxidation of the sprayed powder and bring about prominent metallurgical benefits. However, coatings of Ti and its alloys by CS have been found limited industrial applications compared to other materials (e.g. Cu and Al), partly due to the special particle deposition behavior of Ti and its alloys and the lack of comprehensive knowledge of its control. This review therefore focuses on the deposition characteristics of Ti and its alloys during CS in an effort to shed light on them and expand their applications. The first part presents a brief introduction of CS and the basic characteristics of Ti and its alloys coatings by CS. The second part describes the effects of CS process parameters on the deposition characteristics of Ti and its alloys. The third part discusses the bonding mechanisms of Ti and its alloy particles during CS. The fourth part discusses the strengthening methods such as in-situ shot peening and laser-assisted CS. The coating properties can also be improved with post-spray treatment, such as heat treatment, laser treatment, hot rolling, hot isostatic pressing and friction stir processing. In addition, further applications are suggested, such as protective coatings, biocompatible coatings, and additive manufacturing. Finally, the summary and prospects for the deposition of Ti and its alloys are presented.
To develop ultrafine grains (UFG) in 6.35 mm thick magnesium alloy, stationary shoulder friction stir processing (SSFSP) with steel and copper backing plates was conducted. Steel backing plate ...produced uniform fine grains (FG) size of 4.98, 4.75, 4.12 μm in top, middle, bottom of the stir zone (SZ), respectively. In contrast, copper backing plate tailored microstructure from FG (4.1 μm) in the top to UFG (0.96 μm) in the bottom of SZ. SSFSP produced uniform and gradient microstructures, altering temperature gradient by placing steel and copper backing plates, respectively. It is worth to note that UFG microstructure achieved without usage of external cooling, owning to the copper backing plate. Most of the grains found under ~2 μm size in UFG microstructure. FG and UFG microstructures contributed to the enhancement in the ductility and strength, respectively. UFG resulted in significant improvement in hardness and tensile strength by ~80% and 24% of the base material, respectively. The intensity of strong basal texture throughout the thickness found independent of the backing plate type. Microstructure evolutions across the SZ thickness for both processing conditions are discussed using electron back scattered diffraction (EBSD).
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Stationary shoulder friction stir processing (SSFSP) in thick AZ31B magnesium alloy was performed to refine the microstructure followed by evaluating corrosion behavior. The use of stationary ...shoulder exhibited low heat input and small temperature gradient across the thickness of stir zone (SZ). Moreover, smooth surface morphology with little flash was obtained. The probe-dominated SZ developed fine equiaxed uniform grain structure across the thickness of SZ, which in turn increased the corrosion resistance of SSFSPed alloy as compared to BM. SSFSPed alloy surface confirm uniform corrosion behavior with mud cracking and intergranual corrosion patterns instead of pitting corrosion in BM. This improvement in corrosion was attributed to homogenization of magnesium alloy microstructure by using low-heat-input stationary shoulder tool.
Non‐small‐cell lung cancer (NSCLC) is a cancer with high morbidity and mortality. We aimed to define the effect of Go‐Ichi‐Ni‐San complex subuint 2 (GINS2) acting on NSCLC. The expressions of GINS2 ...in NSCLC tissues and cells were detected using real‐time quantitative polymerase chain reaction, western blot, and immunohistochemistry (IHC). The relationship between GINS2 expression and NSCLC prognosis or clinicopathologic features was analyzed through statistical analysis. The overexpressed or downexpressed plasmids of GINS2 were transfected into NSCLC cell lines, and then cell proliferation, invasion, and migration viability were, respectively, determined by Cell Counting Kit‐8 assay, transwell, and wound healing assay. The epithelial–mesenchymal transition (EMT) was observed and the EMT‐related proteins were measured using IHC and western blot. The function of GINS2 in vivo was assessed by mice model. The related proteins of mitogen‐activated protein kinase (MEK)/extracellular signal‐regulated kinase (ERK) and phosphoinositide‐3‐kinase/protein kinase B (PI3K/Akt) pathways were evaluated using western blot. GINS2 expression was upregulated in NSCLC tissues and cell lines, and its high expression was correlated with the poor prognosis and several clinicopathologic features, such as TMN stages (tumor size, lymph node, and metastasis) and clinical stages. GINS2 enhanced NSCLC cell proliferation, migration, and invasion viability in vivo and in vitro. GINS2 also promoted NSCLC cells EMT. In addition, GINS2 could regulate phosphorylated proteins of PI3K p85, Akt, MEK, and ERK expressions, it revealed that GINS2 effected on PI3K/Akt and MEK/ERK pathways. GINS2 promoted cell proliferation, migration, invasion, and EMT via modulating PI3K/Akt and MEK/ERK signaling pathways. It might be a target in NSCLC treatment.
This paper demonstrated that Go‐Ichi‐Ni‐San complex subuint 2 (GINS2) was highly expressed in non‐small‐cell lung cancer (NSCLC) tissues and cell lines. GINS2 promoted cell proliferation, migration, and invasion of NSCLC in vivo and in vitro. GINS2 also accelerated the epithelial–mesenchymal transition in NSCLC via regulating the phosphoinositide‐3‐kinase/protein kinase B and MEK/extracellular signal‐regulated kinase signaling pathways. Our results might suggest that GINS2 was a potential target in NSCLC molecular therapy.
High entropy alloys (HEAs) are of great interest in the community of materials science and engineering due to their unique phase structure. They are constructed with five or more principal alloying ...elements in equimolar or near-equimolar ratio. Therefore, HEAs can derive their performance from multiple principal elements rather than a single element. In this work, solid-state cold spraying (CS) was applied for the first time to produce FeCoNiCrMn HEA coating. The experimental results confirm that CS can be used to produce a thick HEA coating with low porosity. As a low-temperature deposition process, CS completely retained the HEA phase structure in the coating without any phase transformation. The characterization also reveals that the grains in the CSed HEA coating had experienced significant refinement as compared to those in the as-received HEA powder due the occurrence of dynamic recrystallization at the highly deformed interparticle region. Due to the increased dislocation density and grain boundaries, CSed HEA coating was much harder than the as-received powder. The tribological study shows that the CSed FeCoNiCrMn HEA coating resulted in lower wear rate than laser cladded HEA coatings.
Form-focused instruction (FFI) can help second language (L2) learners notice the forms of language, which is conducive to the acquisition of linguistic forms. Two types of FFIs had been proposed, ...including
(FonFs) and
(FonF). Previously, studies on FFI in L2 classroom teaching have focused mainly on the influence of two types of FFIs on the L2 acquisition of grammar and vocabulary. The influence of FonFs and FonF on L2 oral production, however, has been addressed less often. The advantages and disadvantages of different teaching methods in FonFs and FonF have not been well investigated. On the basis of Schmidt's noticing hypothesis, VanPatten's input processing hypothesis, and Long's interactive hypothesis, we investigated the effects of teaching goals, teaching steps, and interactive activities in FonFs and FonF on the complexity, accuracy, and fluency of 32 native Korean speakers' L2 Chinese oral production. We found that FFI significantly improved the performance of L2 Chinese oral production, although different FFIs had different effects on complexity, accuracy, and fluency. FonF and FonFs could improve both complexity and accuracy, whereas FonF also significantly improved fluency, which was not observed in FonFs. Furthermore, we found that the level of L2 proficiency could modulate the interaction between instruction methods and learning outcomes. For low-proficiency learners, FonF was more helpful for the improvement of fluency. For high-proficiency learners, FonFs was more helpful for the improvement of accuracy. These results demonstrated that teachers should pay attention to the interaction between specific teaching conditions with different L2 proficiency and learning outcomes when implementing FFI. The findings of this study have important implications for the design of procedures and interactive activities of L2 spoken Chinese teaching.
Objective
Relevant publications were identified by searching PubMed, EMBASE, Cochrane Central Register of Controlled Trials and Web of Science before December 1, 2019. Studies in which ≥ 10 cases of ...colorectal lesions were resected with endoscopic full-thickness resection (EFTR) were included. Rates of efficacy (technical success (en bloc), full-thickness resection and R0 resection), rates of safety (bleeding, perforation and postpolypectomy syndrome) and rates of follow-up (residual/recurrent adenoma, fate of over-the-scope clip and surgery for any reason) were pooled and analyzed. Forest plots were graphed based on random effects models. Subgroup analyses and sensitivity analyses were also performed if significant heterogeneity existed.
Results
A total of 469 patients across 9 studies were eligible for analysis. The pooled rates of technical success, full-thickness resection and R0 resection were 94.0% (95% CI 89.8–97.3%), 89.5% (83.9–94.2%) and 84.9% (75.1–92.8%), respectively. The pooled estimates of bleeding, perforation and postpolypectomy syndrome were 2.2% (95% CI 0.4–4.9%), 0.19% (95% CI 0.00–1.25%) and 2.3% (95% CI 0.1–6.3%), respectively. Finally, the pooled rates of residual/recurrent adenoma, fate of OTSC and surgery for any reason were 8.5% (95% CI 4.1–14.0%), 80.3% (95% CI 67.5–90.8%) and 6.3% (2.4–11.7%), respectively.
Conclusions
EFTR for nonlifting, invasive lesions in the colon and rectum appears to be effective and safe. However, future studies are necessary to explore the role of EFTR in large colorectal lesions and specify its indications.
Melanin is a biological pigment formed by indoles and phenolic compounds. It is widely found in living organisms and has a variety of unique properties. Due to its diverse characteristics and good ...biocompatibility, melanin has become the focus in the fields of biomedicine, agriculture, the food industry, etc. However, due to the wide range of melanin sources, complex polymerization properties, and low solubility of specific solvents, the specific macromolecular structure and polymerization mechanism of melanin remain unclear, which significantly limits the further study and application of melanin. Its synthesis and degradation pathways are also controversial. In addition, new properties and applications of melanin are constantly being discovered. In this review, we focus on the recent advances in the research of melanin in all aspects. Firstly, the classification, source, and degradation of melanin are summarized. Secondly, a detailed description of the structure, characterization, and properties of melanin is followed. The novel biological activity of melanin and its application is described at the end.
Natural products are important sources for the discovery of new biopesticides to control the worldwide destructive pests Acyrthosiphon pisum Harris. Here, insecticidal substances were discovered and ...characterized from the secondary metabolites of the bio-control microorganism Bacillus velezensis strain ZLP-101, as informed by whole-genome sequencing and analysis. The genome was annotated, revealing the presence of four potentially novel gene clusters and eight known secondary metabolite synthetic gene clusters. Crude extracts, prepared through ammonium sulfate precipitation, were used to evaluate the effects of strain ZLP-101 on Acyrthosiphon pisum Harris aphid pests via exposure experiments. The half lethal concentration (LC50) of the crude extract from strain ZLP-101 against aphids was 411.535 mg/L. Preliminary exploration of the insecticidal mechanism revealed that the crude extract affected aphids to a greater extent through gastric poisoning than through contact. Further, the extracts affected enzymatic activities, causing holes to form in internal organs along with deformation, such that normal physiological activities could not be maintained, eventually leading to death. Isolation and purification of extracellular secondary metabolites were conducted in combination with mass spectrometry analysis to further identify the insecticidal components of the crude extracts. A total of 15 insecticidal active compounds were identified including iturins, fengycins, surfactins, and spergualins. Further insecticidal experimentation revealed that surfactin, iturin, and fengycin all exhibited certain aphidicidal activities, and the three exerted synergistic lethal effects. This study improved the available genomic resources for B. velezensis and serves as a foundation for comprehensive studies of the insecticidal mechanism by Bacillus velezensis ZLP-101 in addition to the active components within biological control strains.
In this paper, an analysis on the residual stress evolution of cold-sprayed copper coatings on Cu and Al substrates was performed. To investigate the influences of particle velocity, temperature and ...material combination on the final residual stresses, an integrated frame of calculation was proposed based on the simulation results obtained from the developed thermo-mechanically coupled Eulerian model. In a single Cu splat, generally speaking, the maximum residual stress and plastic deformation are concentrated at the outside contact zone rather than at the center point of initial impact. The action of friction shear between the particle and substrate during impacting should be considered as one of the essential factors on the final residual stress. And the states of residual stresses can vary significantly depending on the material combination, particle velocity, and temperature. In a single pass Cu coating, the residual stress fluctuates across the coating and there exists both compressive stress and tensile stress within the coating. At a certain range of impacting velocities, the resultant residual stresses increase with the increase of particle velocity. The present simulated results are related to the reported experiments by others, showing that the residual stress states and stress change trend are different from some of the reported results.
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