Improving Wear Resistance and Corrosive Resistance of Cemented Carbide for Mud Pulser Rotor by Deep Cryogenic Treatment.

Cemented carbide used in the rotor of a mud pulser is subjected to the scouring action of solid particles and corrosive mud media for a long time, which causes abrasive wear and electrochemical corrosion. To improve the wear and corrosive resistance of cemented carbide, samples with different cobalt content (WC-5Co, WC-8Co, and WC-10Co) receive deep cryogenic treatment (DCT) at -196 °C for 2.5 h. An optical metalloscope (OM) and X-ray diffractometer (XRD) are used to observe the phase changes of cemented carbides, and the XRD is also used to observe the change in residual stress on the cemented carbide's surface. A scanning electron microscope (SEM) is used to characterize the wear and electrochemical corrosion surface microstructure of cemented carbides (untreated and DCT). The results show that the DCT promotes the precipitation of the η phase, and the diffraction peak of ε-Co tends to intensify. Compared with the untreated, the wear rates of WC-5Co, WC-8Co, and WC-10Co can be reduced by 14.71%, 37.25%, and 41.01% by DCT, respectively. The wear form of the cemented carbides is mainly the extrusion deformation of Co and WC shedding. The precipitation of the η phase and the increase in WC residual compressive stress by DCT are the main reasons for the improvement of wear resistance. The electrochemical corrosion characteristic is the dissolution of the Co phase. DCT causes the corrosion potential of cemented carbide to shift forward and the corrosion current density to decrease. The enhancement of the corrosion resistance of cemented carbide caused by DCT is due to the Co phase transition, η phase precipitation, and the increase in the compressive stress of cemented carbide.

Efficacy and safety of different doses of ropivacaine for laparoscopy-assisted infiltration analgesia in patients undergoing laparoscopic cholecystectomy: A prospective randomized control trial.

BACKGROUND: Wound infiltration analgesia provides effective postoperative pain control in patients undergoing laparoscopic cholecystectomy (LC). However, the efficacy and safety of wound infiltration with different doses of ropivacaine is not well defined. This study investigated the analgesic effects and pharmacokinetic profile of varying concentrations of ropivacaine at port sites under laparoscopy assistance. METHODS: In this randomized, double-blinded study, 132 patients were assigned to 4 groups: Group H: in which patients were infiltrated with 0.75% ropivacaine; Group M: 0.5% ropivacaine; Group L: 0.2% ropivacaine; and Group C: 0.9% normal saline only. The primary outcome was pain intensity estimated using numeric rating scale (NRS) at discharging from PACU and at 4 hours, 6 hours, 8 hours, and 24 hours after infiltration. Secondary outcomes included plasma concentrations of ropivacaine at 30 minutes after wound infiltration, rescue analgesia requirements after surgery, perioperative vital signs changes, and side effects. RESULTS: The NRS in Group C was significantly higher at rest, and when coughing upon leaving PACU and at 4 hours, 6 hours, 8 hours, and 24 hours after infiltration (P < .05) and rescue analgesic consumption was significantly higher. Notably, these parameters were not significantly different between Groups H, Group M and Group L (P > .05). Intra-operative consumption of sevoflurane and remifentanil, HR at skin incision and MAP at skin incision, as well as 5 minutes after skin incision were significantly higher in Group C than in the other 3 groups (P < .01). In contrast, these parameters were not significantly different between Groups H, Group M and Group L (P > .05). The concentration of ropivacaine at 30 minutes after infiltration in Group H was significantly higher than that of Group L and Group M (P < .05). No significant differences were observed in the occurrence of side effects among the 4 groups (P > .05). CONCLUSIONS: Laparoscopy-assisted wound infiltration with ropivacaine successfully decreases pain intensity in patients undergoing LC regardless of the doses used. Infiltration with higher doses results in higher plasma concentrations, but below the systematic toxicity threshold.

[Association between platelet-derived growth factor-C single nucleotide polymorphisms and nonsyndromic cleft lip with or without cleft palate in Western Chinese population].

OBJECTIVE: To explore the association between two single nucleotide polymorphisms (SNPs), namely, rs4691383 and rs7667857, in the platelet-derived growth factor-C (PDGF-C) gene, the genotypes, environmental exposure factors, and nonsyndromic cleft lip with or without cleft palate (NSCL/P) in Western Chinese population. METHODS: A total of 268 case-parent trios were selected, and two SNPs (rs4691383 andrs7667857) were genotyped by using polymerase chain reaction and restriction enzyme fragment length polymorphic method and direct sequencing method. Hardy-Weinberg equilibrium, linkage disequilibrium test, transmission disequilibrium test, and haplotype analysis were conducted to analyze the data. Meanwhile, the questionnaires on the epidemiology of cleft lip and palate filled by the included samples were collected, and the interaction between the genotypes of the two SNPs and environmental exposure factors was assessed by conditional logistic regression. RESULTS: The A allele at rs4691383 and the G allele at rs7667857 of PDGF-C gene were over-transmitted for NSCL/P (P<0.05). No interaction effect was observed between the three environmental exposure factors (history of smoking/passive smoking, folic acid supplementation, and long-term inhalation of harmful environmental gases) and the PDGF-C genotypes among NSCL/P (P>0.05). CONCLUSIONS: The rs4691383 and rs7667857 at PDGF-C gene are closely related to the occurrence of NSCL/P in Western Chinese population. However, the interaction between environmental exposure factors and PDGF-C genotypes is not obvious in the occurrence of NSCL/P.

Evaluation of the association of polymorphisms in EYA1, environmental factors, and non-syndromic orofacial clefts in Western Han Chinese.

BACKGROUND: Non-syndromic orofacial clefts (NSOCs) are complex disease involving genetic triggers, environmental factors, and their interplay. Recent studies demonstrated that EYA1, a member of eye absent gene family, might contribute to NSOCs. METHODS: We investigated three single nucleotide polymorphisms (SNPs) and eight environmental factors (multivitamin, folic acid and calcium supplementation history, maternal alcohol consumption, common cold history, maternal smoking and environmental tobacco smoke in the first trimester, and paternal smoking in the 3 months before pregnancy) among 294 case-parent trios and 183 individual controls in western Han Chinese to evaluate the relationship between EYA1, environmental factors, and NSOCs. To be better known the gene's role in the etiology of NSOCs, we performed statistical analysis in different aspects including the linkage disequilibrium test, transmission disequilibrium test, haplotype analysis, multiple logistic regression analysis, and conditional logistic regression analysis. RESULTS: Allele C at rs3779748 showed an over-transmission in NSCL/P trios (P = 0.03), and genotype A/A at rs10094908 was under-transmitted among NSCL/P trios (P = 0.03), whereas over-transmitted among NSCPO trios (P = 0.02). The haplotype GC of rs10094908-rs3779748 was over-transmitted among NSCL/P trios (P = 0.05) and NSCPO trios (P = 0.05), respectively. Maternal common cold history, environmental tobacco smoke, and maternal alcohol consumption during the first trimester of pregnancy were risk factors for NSOCs, while calcium supplementation during the first trimester showed a protective effect. No evidence of interactions between EYA1 and environmental factors was found. CONCLUSIONS: These results revealed an association between EYA1, some environmental factors, and NSOCs in western Han Chinese.