The evolutionary origin and domestication history of goldfish (Carassius auratus).

Goldfish have been subjected to over 1,000 y of intensive domestication and selective breeding. In this report, we describe a high-quality goldfish genome (2n = 100), anchoring 95.75% of contigs into 50 pseudochromosomes. Comparative genomics enabled us to disentangle the two subgenomes that resulted from an ancient hybridization event. Resequencing 185 representative goldfish variants and 16 wild crucian carp revealed the origin of goldfish and identified genomic regions that have been shaped by selective sweeps linked to its domestication. Our comprehensive collection of goldfish varieties enabled us to associate genetic variations with a number of well-known anatomical features, including features that distinguish traditional goldfish clades. Additionally, we identified a tyrosine-protein kinase receptor as a candidate causal gene for the first well-known case of Mendelian inheritance in goldfish-the transparent mutant. The goldfish genome and diversity data offer unique resources to make goldfish a promising model for functional genomics, as well as domestication.

How dignity-related distress interacts with quality of life in young adult patients with cancer during the active treatment stage: A network analysis.

OBJECTIVE: Young adult patients with cancer are a growing concern. By means of network analysis, this study aimed to explore the interplay between dignity-related distress and quality of life (QoL) in young adult patients with cancer when they undergo active treatments. METHODS: In this cross-sectional study, 309 young adults aged 18-39 and diagnosed with malignant tumors were recruited from an oncology center in China between September 2020 and August 2021. Participants completed the Patient Dignity Inventory and SF-36 questionnaires. Network analysis was applied to examine the network structure. RESULTS: Overall, the core facets of dignity-related distress were negatively related to QoL and its corresponding domains, either directly or indirectly. Developmental distress played a central role among estimated networks and strongly interplayed with most QoL domains, especially the mental domains. Symptom distress was the only facet consistently interplayed with the physical domains of QoL (i.e., physical function and bodily pain). The social aspects were also revealed in the association between limited social support and vitality. CONCLUSIONS: Early attention must be paid to guarantee the need of preserving dignity and enhancing QoL for young adult patients.

Astragalus mongholicus Bunge-Curcuma aromatica Salisb. suppresses growth and metastasis of colorectal cancer cells by inhibiting M2 macrophage polarization via a Sp1/ZFAS1/miR-153-3p/CCR5 regulatory axis.

Colorectal cancer (CRC) is regarded as one of the commonest cancer types around the world. Due to the poor understanding on the causes of CRC formation and progression, this study sets out to investigate the physiological mechanisms by which Astragalus mongholicus Bunge-Curcuma aromatica Salisb. (ARCR) regulates CRC growth and metastasis, and the role in which M2 macrophage polarization plays in this process. An orthotopic-transplant model of CRC was established to evaluate the influence of ARCR on the polarization of M2 macrophage and the growth and metastasis of tumors. Next, the binding affinity among Sp1, ZFAS1, miR-153-5p, and CCR5 was identified using multiple assays. Finally, after co-culture of bone marrow-derived macrophages (BMDM) with CRC cell line CT26.WT, the cell proliferative, invasive, and migrated abilities were assessed in gain- or loss-of-function experiments. ARCR inhibited the infiltration of M2 macrophages into tumor microenvironment to suppress the CRC growth and metastasis in vivo. Additionally, ARCR inhibited the transcription of ZFAS1 by reducing Sp1 expression to repress M2 macrophage polarization. Moreover, ZFAS1 competitively binds to miR-153-3p to upregulate the CCR5 expression. Finally, ARCR suppressed the polarization of M2 macrophages to inhibit the tumor growth and tumor metastasis in CRC by mediating the Sp1/ZFAS1/miR-153-3p/CCR5 regulatory axis. Collectively, ARCR appears to suppress the CRC cell growth and metastasis by suppressing M2 macrophage polarization via Sp1/ZFAS1/miR-153-3p/CCR5 regulatory axis. 1. ARCR suppress the CRC cell growth and metastasis 2. ZFAS1 promotes CCR5 expression by competitively binding to miR-153-3p. 3. Sp1 promotes M2 macrophage polarization by activating ZFAS1 via miR-153-3p/CCR5. 4. The study unveiled a protective target against CRC.

Cotton D genome assemblies built with long-read data unveil mechanisms of centromere evolution and stress tolerance divergence.

BACKGROUND: Many of genome features which could help unravel the often complex post-speciation evolution of closely related species are obscured because of their location in chromosomal regions difficult to accurately characterize using standard genome analysis methods, including centromeres and repeat regions. RESULTS: Here, we analyze the genome evolution and diversification of two recently diverged sister cotton species based on nanopore long-read sequence assemblies and Hi-C 3D genome data. Although D genomes are conserved in gene content, they have diversified in gene order, gene structure, gene family diversification, 3D chromatin structure, long-range regulation, and stress-related traits. Inversions predominate among D genome rearrangements. Our results support roles for 5mC and 6mA in gene activation, and 3D chromatin analysis showed that diversification in proximal-vs-distal regulatory-region interactions shape the regulation of defense-related-gene expression. Using a newly developed method, we accurately positioned cotton centromeres and found that these regions have undergone obviously more rapid evolution relative to chromosome arms. We also discovered a cotton-specific LTR class that clarifies evolutionary trajectories among diverse cotton species and identified genetic networks underlying the Verticillium tolerance of Gossypium thurberi (e.g., SA signaling) and salt-stress tolerance of Gossypium davidsonii (e.g., ethylene biosynthesis). Finally, overexpression of G. thurberi genes in upland cotton demonstrated how wild cottons can be exploited for crop improvement. CONCLUSIONS: Our study substantially deepens understanding about how centromeres have developed and evolutionarily impacted the divergence among closely related cotton species and reveals genes and 3D genome structures which can guide basic investigations and applied efforts to improve crops.

[Anti-colorectal cancer mechanism of Astragali Radix-Curcumae Rhizoma-Paridis Rhizoma based on network pharmacology and experimental verification].

The present study explored the underlying mechanism of Astragali Radix-Curcumae Rhizoma-Paridis Rhizoma(AR-CR-PR) in the treatment of colorectal cancer(CRC) by network pharmacology and molecular docking and animal tests and verified the core targets based on the orthotopic transplantation model in nude mice. The active components of AR-CR-PR were retrieved from databases such as TCMSP. The targets of drugs and the disease were obtained from PubChem, SwissTargetPrediction, TTD, and DrugBank, and the intersection targets were imported into STRING for the analysis of the protein-protein interaction(PPI). Gene Ontology(GO) and Kyoto Encyclopedia of Genes and Genomes(KEGG) analyses were performed through DAVID. AutoDock Vina was used to perform molecular docking and binding ability prediction between the active components and the core targets. The effects of AR-CR-PR on tumor growth, metastasis, and phosphorylation of core target proteins in tumor tissues based on the orthotopic transplantation model in nude mice. As revealed by network pharmacology, AR-CR-PR contained nine core components, such as quercetin, curcumin, and ß-ecdysone, and the key targets included protein kinase B(AKT1), mitogen-activated protein kinase 3(MAPK3), MAPK1, and epithelial growth factor receptor(EGFR), which was indicated that the anti-CRC effect of AR-CR-PR was presumedly achieved by regulating tumor cell proliferation, apoptosis, migration, and angiogenesis through PI3 K-AKT, MAPK and other signaling pathways. The results of molecular docking showed that the nine core components had strong binding abilities to AKT1 and MAPK3. The results in vivo showed that AR-CR-PR could reduce the volume of the orthotopic tumor, inhibit liver metastasis, and decrease the phosphorylation of AKT1 and MAPK3 in the CRC model. The mechanism of AR-CR-PR in the intervention of CRC may be related to the activation of PI3 K-AKT and MAPK signaling pathway. This study provides a scientific basis for the clinical application of AR-CR-PR in the treatment of CRC and ideas for modern research on AR-CR-PR.

Insulin Glargine and Acarbose in the treatment of elderly patients with diabetes.

OBJECTIVE: To investigate the clinical efficacy of insulin glargine combined with acarbose in the treatment of elderly patients with diabetes. METHODS: One hundred and forty-four elderly patients with diabetes who received treatment between December 2016 and December 2017 in Binzhou People's Hospital, China, were selected and divided into a control group and an observation group, 72 each, using random number table. The control group was treated with insulin glargine, while the observation group was treated with insulin glargine combined with acarbose. The therapeutic effect, improvement of quality of life and adverse reactions were compared between the two groups. RESULTS: After treatment, fasting blood glucose (FBG), 2h postprandial blood glucose (PBG) and glycosylated hemoglobin (Hb Alc) of the two groups were lower than those before treatment, and the decrease degree of the observation group was significantly larger than that of the control group (P<0.05). The time needed for blood glucose reaching the standard level and daily insulin dosage of the observation group were significantly lower than that of the control group, and the differences were statistically significant (P<0.05). SF-36 scale score of the observation group was significantly better than the control group, and the difference was statistically significant (P<0.05). There was no significant difference in the incidence of adverse reactions between the two groups (P>0.05). CONCLUSION: The combination of insulin Glargine and Acarbose can significantly control the blood glucose level of elderly patients with diabetes, improve the biochemical indicators, and enhance the quality of life. It is worth promotion in clinical practice.

Porous Co3O4 nanosheets as a high-performance non-enzymatic sensor for glucose detection.

Novel porous Co3O4 nanosheets (NSs) were synthesized on the flexible carbon cloth (CC) substrate by a facile hydrothermal method and applied to construct a non-enzymatic sensor for glucose detection. The sensor is based on the electro-catalytic oxidation of glucose on the surface of Co3O4 NSs. Since this particular nanostructure can provide large surface area and more active sites, the Co3O4 NSs non-enzymatic sensor exhibits excellent analytical performance, such as a high sensitivity (8506 µA mM-1 cm-2), a fast response time (less than 6 s), low detection limit of 1 µM, good selectivity, and long-term stability. The results suggest that the porous Co3O4 NSs have great potential applications in the development of sensors for enzyme-free detection of glucose.

[Allele-specific PCR to identification of Achyranthis Bidentatae Radix and Cyathulae Radix formula granules].

To establish a robust and accuracy molecular method to identify Achyranthis Bidentatae Radix and Cyathulae Radix formula granules. ITS sequences of Achyranthes bidentata and Cyathula officinalis were aligned, specific SNPs (single nucleotide polymorphisms) were excavated, specific primers were designed and allele-specific PCR method was established. The genomic DNA was successfully extracted from the herbal medicine and its formula granules by using an improved CTAB (cetyltrimethyl ammonium bromide) method and then performed PCR with the designed primers. The 187 bp specific band could be amplified only in the presentation of C. officinalis and its granules when use of C. officinalis specific primers, whereas the 162 bp band could be amplified only in the presentation of A. bidentata and its granules when use of A. bidentata specific primers. This method was also successfully applied in the identification of commercial formula granules.

[Zoological origin survey of commercial hippocampus in Chinese herbal markets by morphological and DNA sequencing identification].

Hippocampus is a precious animal medicine in Chinese herbal medicines. Numerous seahorse species possessing similar morphology were used as commercial hippocampus in herbal markets. Clarifing the zoological of commercial hippocampus in herbal markets is a crucial issue, which contributed to establish authentication and quality control standard. This study investigated 1 156 dried seahorse samples collected from eight main herbal markets using CO Ⅰ fragment DNA sequencing coupling with morphological identification. The results showed that 23 seahorse species were present in the China TCM market. Among them, five species were officially listed in China Pharmacopoeia, seven species namely winged seahorse (Hippocampus alatus), giraffe seahorse (H. camelopardalis), knysna seahorse (H. capensis), beibuwan seahorse (H. casscsio), half-spiny seahorse (H. semispinosus), Europe seahorse (H. hippocampus), zebra seahorse (H. zebra) were found in herbal markets for the first time. The present DNA sequences analysis coupling with morphological identification method could also use to survey the species origin of other Chinese herbal medicines in herbal markets.

[Specific PCR method for identification of Trionycis Carapax and its preparation].

Trionycis Carapax is a commonly used animal medicine in Chinese medicine. It's difficult to identify Trionycis Carapax and its adulterants because of the loss of morphological characteristics after processing. To establish an efficient and stable method to identification Trionycis Carapax, this study combines SDS method with column purification to extract genomic DNA, uses universal primers for polymerase chain reaction (PCR) amplification and sequencing, and designs the specific primers based on the differences in the sequences of Pelodiscus sinensis and their adulterants. When the annealing temperature was 62 °C and the number of cycles was 35, the designed primer Biejia-272.F/R was used for PCR amplification and got optimum results. The crude drug and preparation of P. sinensis were all amplified to obtain a specific band of approximately 300 bp, while the adulterants showed no such a band. This method can be used as a rapid and accurate method to identify the authenticate of P. sinensis.

[Multiplex PCR to simultaneous identification of five traditional Chinese medicinal seahorses].

Seahorse is one the most commonly used medicinal animal in China. Five species of Hippocampus are recorded as seahorse in the Chinese Pharmacopoeia. Because of the rapid decrease, several other Hippocampus species are often adulterants as medicinal seahorse in the herbal market, which compromise clinical efficacy and pose threat to endangered seahorse species conversation. Herein, a multiplex polymerase chain reaction (mPCR) method was developed to identify the biological sources of medicinal seahorses.Based on the sequences of mitochondrial DNA, five specific primers for Hippocampus trimaculatus, H. kelloggi, H. kuda, H. histrix and H. mohnikei (H. japonicus)were designed, respectively. Multiplex PCR yields the products of 155, 222, 292, 352, 458 bp amplicons in the present of DNA templates of H. kuda, H. mohnikei, H. kelloggi, H. histrix and H. trimaculatus, respectively. This multiplex PCR method which electrophoresis migration of different lengths of DNA bands allowed simultaneous identification of all the five medicinal seahorses in a single assay. It showed that this multiplex PCR assay is useful for the simultaneous identification the biological sources of complex multi-source samples, which could provide a useful tool for the quality control of seahorses.

Adipose tissue-derived stem cells in combination with xanthan gum attenuate osteoarthritis progression in an experimental rat model.

The current study explored the efficacy of an intra-articular (IA) injection of allogeneic adipose tissue-derived stem cells (ADSCs) combined with xanthan gum (XG) in a rat osteoarthritis (OA) model. We confirmed that XG significantly inproved proliferation of ADSCs in a dose dependent manner in vitro. The rat OA model was induced by an anterior cruciate ligament transection (ACLT), and at 4 weeks after surgery, rats were divided into four groups: the XG-ADSCs group, the ADSCs group, the XG group and the phosphate-buffered saline (PBS) group. A single dose of 1 × 106 allogeneic ADSCs suspended in 1% XG, ADSCs suspended in PBS, 1% XG alone or PBS alone was injected into the OA joint of rats in the respective treatment groups. Rats were sacrificed at 8 weeks after surgery. Treatment outcomes were evaluated by weight-bearing control of the hind limbs, gross morphological analysis, histological analysis and specific staining of articular cartilage, and measurement of inflammatory factors in synovial fluid. For the rats in the XG-ADSC-s and ADSCs-treated groups, the weight-bearing percentage of the right hind limb was significantly increased compared to that in the PBS group and was sustained over 4 weeks. However, the positive effect in the XG-ADSCs group was significantly greater than that in the ADSCs group. For the rats in the XG group, the efficacy decreased during the third week after surgery. The articular cartilage was relatively normal in the XG-ADSCs group, and moderate degeneration was observed in the ADSCs and XG groups. ADSCs and XG-ADSC treatments significantly decreased the concentrations of IL-1ß, TNF-α, MMP-3 and MMP-13 in synovial fluid; however, the attenuating effect of the XG-ADSCs treatment was significantly enhanced compared with that of the ADSCs treatment alone. These results indicate that a single IA injection of allogeneic ADSCs combined with XG efficiently attenuated OA progression with a therapeutic effect that was significantly greater than that of either ADSCs or XG alone. IA injection of XG-ADSCs might be an effective treatment for OA in humans.

Anti-Inflammatory Effects of a Mytilus coruscus α-d-Glucan (MP-A) in Activated Macrophage Cells via TLR4/NF-κB/MAPK Pathway Inhibition.

The hard-shelled mussel (Mytilus coruscus) has been used as Chinese traditional medicine for thousands of years; however, to date the ingredients responsible for the various beneficial health outcomes attributed to Mytilus coruscus are still unclear. An α-d-Glucan, called MP-A, was isolated from Mytilus coruscus, and observed to exert anti-inflammatory activity in THP-1 human macrophage cells. Specifically, we showed that MP-A treatment inhibited the production of inflammatory markers, including TNF-α, NO, and PGE2, inducible NOS (iNOS), and cyclooxygenase-2 (COX-2), in LPS-activated THP-1 cells. It was also shown to enhance phagocytosis in the analyzed cells, but to severely inhibit the phosphorylation of mitogen-activated protein kinases (MAPKs) and the nuclear translocation of NF-κB P65. Finally, MP-A was found to exhibit a high binding affinity for the cell surface receptor TLR4, but a low affinity for TLR2 and dectin-1, via surface plasmon resonance (SPR) analysis. The study indicates that MP-A suppresses LPS-induced TNF-α, NO and PEG2 production via TLR4/NF-κB/MAPK pathway inhibition, and suggests that MP-A may be a promising therapeutic candidate for diseases associated with TNF-α, NO, and/or PEG2 overproduction.

[Exploration and thoughts about zoological origin and macroscopical identification of Chinese material medica "Haima" in China Pharmacopoeia].

"Haima" (Hippocampus) has a long history in China as an important traditional animal medicine, but many closely-related members of the Hippocampus genus are also used as Haima in particular regions. To investigate the real origin of "Haima", a herbalogical studies, particularly inpictures and photographs of the ancient literature are corroborated with seahorse specimens in museum, we confirm Chinese material medica "Haima" in China Pharmacopoeia is origin from H. kelloggi, 1901, H.spinosissimus, 1913, H. kuda, 1852, H. trimaculatus, 1814, or H. mohnikei, 1853. The so-called "Ci Haima" is H. spinosissimus, instead of H. histrix, 1856. The paper also suggests to revise of "macroscopical identification" item and add identification methods of "Haima" in China Pharmacopoeia, which may improve quality controls tandards of "Haima".

Meta-analysis of the traditional Chinese medicine care model in relieving postoperative pain in patients with anorectal diseases.

Objective: To explore the effect of traditional Chinese medicine (TCM) nursing on relieving postoperative pain in patients with anorectal diseases. Method: Three English and three Chinese databases (PubMed, Embase, the Cochrane Library, the China National Knowledge Internet, Wanfang Data and the China Science and Technology Journal Database) were systematically searched for case-controlled or prospective studies evaluating the impact of TCM nursing on postoperative pain in patients with anorectal diseases from the date of library construction until June 20, 2022. The Newcastle-Ottawa Scale was adopted to evaluate the quality of the observational studies. The effect of TCM care on pain based on the Visual Analogue Scale (VAS), the effective pain relief rate, the wound healing time and the length of hospital stay were systematically analysed. Result: After a systematic search and screening, a total of 15 documents were included in this study. The systematic evaluation showed that TCM care reduced the VAS score (mean difference (MD): 1.15（95 % Confidence Interval (CI): 1.96, -1.06; P < 0.00001) compared with conventional postoperative care methods. As TCM nursing time increased, there was a trend towards decreased VAS scores. Furthermore, TCM care was effective in providing pain relief (OR: 4.78; 95 % CI: 2.93,7.79; P < 0.00001) and reducing wound healing time (MD: 4.44; 95 % CI: 5.60, -3.27; P < 0.00001) and length of hospital stay (MD: 4.87; 95 % CI: 5.93, -3.82; P < 0.00001). Conclusion: Traditional Chinese medicine nursing has a positive effect on the postoperative clinical results of patients with anorectal diseases, especially in relieving postoperative pain. The effect of traditional Chinese medicine nursing in relieving short-term postoperative pain in patients with anorectal diseases is obvious. However, there is no uniform standard for TCM nursing projects, which may lead to heterogeneity.

N6-methyladenosine modification promotes hepatocarcinogenesis through circ-CDYL-enriched and EpCAM-positive liver tumor-initiating exosomes.

CircRNAs play multiple roles in a variety of cellular processes. We found that Circ-CDYL is highly enriched in early HCC plasma exosomes. Moreover, EpCAM+ HCC cells and exosomes had significant Circ-CDYL levels. We postulated that Circ-CDYL-enriched and EpCAM-positive exosomes would function as liver tumor-initiating exosomes (LTi-Exos). As predicted, intercellular transfer of LTi-Exos activates the HDGF-PI3K-AKT-mTOR and HIF1AN-NOTCH2 axes in recipient cells, promoting malignancy. Upstream, we found that the N6-methyladenosine (m6A) modification of Circ-CDYL exerted its action in HCC cells through a dual mechanism. First, it stimulated back-splicing processes via YTHDC1 to promote Circ-CDYL biogenesis. Second, it facilitates the active sorting of Circ-CDYL into exosomes via hnRNPA2/B1. Clinically, the combination of LTi-Exos and plasma alpha-fetoprotein (AFP) provides a promising early diagnostic biomarker for HCC with an AUC of 0.896. This study highlights the effect and mechanism by which m6A modification promotes hepatocarcinogenesis via modulation of the tumor microenvironment by LTi-Exos.

The male and female genomes of golden pompano (Trachinotus ovatus) provide insights into the sex chromosome evolution and rapid growth.

INTRODUCTION: Golden pompano (Trachinotus ovatus) is economically significant important for offshore cage aquaculture in China and Southeast Asian countries. Lack of high-quality genomic data and accurate gene annotations greatly restricts its genetic breeding progress. OBJECTIVES: To decode the mechanisms of sex determination and rapid growth in golden pompano and facilitate the sex- and growth-aimed genetic breeding. METHODS: Genome assemblies of male and female golden pompano were generated using Illumina, PacBio, BioNano, genetic maps and Hi-C sequencing data. Genomic comparisons, whole genome re-sequencing of 202 F1 individuals, QTL mapping and gonadal transcriptomes were used to analyze the sex determining region, sex chromosome evolution, SNP loci, and growth candidate genes. Zebrafish model was used to investigate the functions of growth candidate gene. RESULTS: Female (644.45 Mb) and male (652.12 Mb) genomes of golden pompano were assembled and annotated at the chromosome level. Both genomes are highly conserved and no new or highly differentiated sex chromosomes occur. A 3.5 Mb sex determining region on LG15 was identified, where Hsd17b1, Micall2 and Lmx1a were putative candidates for sex determination. Three SNP loci significantly linked to growth were pinpointed, and a growth-linked gene gpsstr1 was identified by locus BSNP1369 (G â†’ C, 17489695, Chr23). Loss of sstr1a (homologue of gpsstr1) in zebrafish caused growth retardation. CONCLUSION: This study provides insights into sex chromosome evolution, sex determination and rapid growth of golden pompano.

[Screening and identification of an endophytic fungus from Atractylodes lancea which utilizes volatile oil selectively].

In order to transform main active ingredient of volatile oil, endophytic fungi were screened from the root of Atractylodes lancea. Transformation method was used in vitro. The changes of volatile oil were traced by gas chromatography. One endophytic fungus (strain ALG-13) which could uitilize volatile oil selectively was screened. Single factor experiment were conducted for exploring the effects of various factors that including kinds of carbon source, speed, liquid volume, pH and concentration of plant tissue on degradation by this strain. Subsequently, the main affecting factors carbon source, speed, pH and liquid volume were optimized using orthogonal array design. Results showed that endophytic fungus ALG-13 selectively used the volatile oil, change the relative percentage of the main components of volatile oil, Atractylon and Atractydin were increased, While, beta-eudesmol and Atractylol decreased. After selectively degradation by fungus, volatile oil components percentage were closer to the geo-herbs. Strain ALG-13 was identified as Bionectria ochroleuca according to its morphological characteristics and systematic analysis of ITS sequence. The optimal conditions were as follows: sucrose used as carbon source, rotating speed was 200 r x min(-1), initial pH for medium was 4.5, 50 mL liquid was added in 250 mL flask. The endophytic fungus ALG-13 could degrade the volatile oil selectively, which was benefit for forming geoherbs A. lancea volatile oil composition.

Microstructure and Tribological Properties of Spark-Plasma-Sintered Ti3SiC2-Pb-Ag Composites at Elevated Temperatures.

Ti3SiC2-PbO-Ag composites (TSC-PA) were successfully prepared using the spark plasma sintering (SPS) technique. The ingredient and morphology of the as-synthesized composites were elaborately investigated. The tribological properties of the TSC-PA pin sliding against Inconel 718 alloys disk at room temperature (RT) to 800 °C were examined in air. The wear mechanisms were argued elaborately. The results showed that the TSC-PA was mainly composed of Ti3SiC2, Pb, and Ag. The average friction coefficient of TSC-PA gradually decreased from 0.72 (RT) to 0.3 (800 °C), with the temperature increasing from RT to 800 °C. The wear rate of TSC-PA showed a decreasing trend, with the temperature rising from RT to 800 °C. The wear rate of Inconel 718 exhibited positive wear at RT and negative wear at elevated temperatures. The tribological property of TSC-PA was related to the tribo-chemistry, and the abrasive and adhesive wear.

Microstructure and Mechanical Properties of Composites Obtained by Spark Plasma Sintering of Ti3SiC2-15 vol.%Cu Mixtures.

Method of soft metal (Cu) strengthening of Ti3SiC2 was conducted to increase the hardness and improve the wear resistance of Ti3SiC2. Ti3SiC2/Cu composites containing 15 vol.% Cu were fabricated by Spark Plasma Sintering (SPS) in a vacuum. The effect of the sintering temperature on the phase composition, microstructure and mechanical properties of the composites was investigated in detail. The as-synthesized composites were thoroughly characterized by scanning electron micrography (SEM), optical micrography (OM) and X-ray diffractometry (XRD), respectively. The results indicated that the constituent of the Ti3SiC2/Cu composites sintered at different temperatures included Ti3SiC2, Cu3Si and TiC. The formation of Cu3Si and TiC originated from the reaction between Ti3SiC2 and Cu, which was induced by the presence of Cu and the de-intercalation of Si atoms Ti3SiC2. OM analysis showed that with the increase in the sintering temperature, the reaction between Ti3SiC2 and Cu was severe, leading to the Ti3SiC2 getting smaller and smaller. SEM measurements illustrated that the uniformity of the microstructure distribution of the composites was restricted by the agglomeration of Cu, controlling the mechanical behaviors of the composites. At 1000 °C, the distribution of Cu in the composites was relatively even; thus, the composites exhibited the highest density, relatively high hardness and compressive strength. The relationships of the temperature, the current and the axial dimension with the time during the sintering process were further discussed. Additionally, a schematic illustration was proposed to explain the related sintering characteristic of the composites sintered by SPS. The as-synthesized Ti3SiC2/Cu composites were expected to improve the wear resistance of polycrystalline Ti3SiC2.