AIM To perform a meta-analysis on laparoscopic hepatectomy VS conventional liver resection for treating hepatolithiasis.METHODS We conducted a systematic literature search on Pub Med,Embase,Web of Science and Cochrane...AIM To perform a meta-analysis on laparoscopic hepatectomy VS conventional liver resection for treating hepatolithiasis.METHODS We conducted a systematic literature search on Pub Med,Embase,Web of Science and Cochrane Library,and undertook a meta-analysis to compare the efficacy and safety of laparoscopic hepatectomy V S conventional open liver resection for local hepatolithiasis in the left or right lobe. Intraoperative and postoperative outcomes(time,estimated blood loss,blood transfusion rate,postoperative intestinal function recovery time,length of hospital stay,postoperative complication rate,initial residual stone,final residual stone and stone recurrence) were analyzed systematically.RESULTS A comprehensive literature search retrieved 16 publications with a total of 1329 cases. Meta-analysis of these studies showed that the laparoscopic approach for hepatolithiasis was associated with significantly less intraoperative estimated blood loss [weighted mean difference(WMD): 61.56,95% confidence interval(CI): 14.91-108.20,P = 0.01],lower blood transfusion rate [odds ratio(OR): 0.41,95%CI: 0.22-0.79,P = 0.008],shorter intestinal function recovery time(WMD: 0.98,95%CI: 0.47-1.48,P = 0.01),lower total postoperative complication rate(OR: 0.52,95%CI: 0.39-0.70,P < 0.0001) and shorter stay in hospital(WMD: 3.32,95%CI: 2.32-4.32,P < 0.00001). In addition,our results showed no significant differences between the two groups in operative time(WMD: 21.49,95%CI: 0.27-43.24,P = 0.05),residual stones(OR: 0.79,95%CI: 0.50-1.25,P = 0.31) and stone recurrence(OR: 0.34,95%CI: 0.11-1.08,P = 0.07). Furthermore,with subgroups analysis,our results proved that the laparoscopic approach for hepatolithiasis in the left lateral lobe and left side could achieve satisfactory therapeutic effects. CONCLUSION The laparoscopic approach is safe and effective,with less intraoperative estimated blood loss,fewer postoperative complications,reduced length of hospital stay and shorter intestinal function recovery time than with conventional approaches.展开更多
AIM To perform a systematic review and meta-analysis on minimally vs conventional invasive techniques for harvesting grafts for living donor liver transplantation. METHODS PubMed, Web of Science, EMBASE, and the Cochr...AIM To perform a systematic review and meta-analysis on minimally vs conventional invasive techniques for harvesting grafts for living donor liver transplantation. METHODS PubMed, Web of Science, EMBASE, and the Cochrane Library were searched comprehensively for studies comparing MILDH with conventional living donor hepatectomy (CLDH). Intraoperative and postoperative outcomes (operative time, estimated blood loss, postoperative liver function, length of hospital stay, analgesia use, complications, and survival rate) were analyzed in donors and recipients. Articles were included if they: (1) compared the outcomes of MILDH and CLDH; and (2) reported at least some of the above outcomes. RESULTS Of 937 articles identified, 13, containing 1592 patients, met our inclusion criteria and were included in the meta-analysis. For donors, operative time [weighted mean difference (WMD) = 20.68, 95% CI: -6.25-47.60, p = 0.13] and blood loss (WMD = -32.61, 95% CI: -80.44-5.21, p = 0.18) were comparable in the two groups. In contrast, analgesia use (WMD = -7.79, 95% CI: -14.06-1.87, p = 0.01), postoperative complications [odds ratio (OR) = 0.62, 95% CI: 0.44-0.89, p = 0.009], and length of hospital stay (WMD): -1.25, 95% CI: -2.35-0.14, p = 0.03) significantly favored MILDH. No differences were observed in recipient outcomes, including postoperative complications (OR = 0.93, 95% CI: 0.66-1.31, p = 0.68) and survival rate (hr = 0.96, 95% CI: 0.27-3.47, p = 0.95). Funnel plot and statistical methods showed a low probability of publication bias. CONCLUSION MILDH is safe, effective, and feasible for living donor liver resection with fewer donor postoperative complications, reduced length of hospital stay and analgesia requirement than CLDH.展开更多
Objective Isocitrate dehydrogenase gene(IDH)mutations are associated with tumor angiogenesis and therefore play an important role in glioma management.This study compared the performance of tumor blood vessels counted...Objective Isocitrate dehydrogenase gene(IDH)mutations are associated with tumor angiogenesis and therefore play an important role in glioma management.This study compared the performance of tumor blood vessels counted from contrast-enhanced 3D brain volume(3D-BRAVO)sequence and dynamic contrast-enhanced(DCE)MRI in differentiating IDH1 status in gliomas.Methods Forty-four glioma patients[16 with IDH1 mutant-type(IDH1-MT),28 with IDH1 wild-type(IDH1-WT)]were retrospectively analyzed.A blood vessel entering a tumor was defined as an intratumoral vessel;a blood vessel adjacent to the edge of a tumor was defined as a peritumoral vessel.Combined vessels were defined as the sum of the intratumoral and peritumoral vessels.DCE-derived metrics of tumor were normalized to the contralateral normal-appearing white matter.Results Intratumoral,peritumoral,and combined tumor blood vessels were all significantly different between IDH1-MT and IDH1-WT gliomas,and the range of area under curves(AUCs)was 0.816–0.855.For DCE-derived parameters,cerebral blood volume,cerebral blood flow,mean transit time,and volume transfer constant were significantly different between IDH1-MT and IDH1-WT gliomas,and the range of AUCs was 0.703–0.756.Combined vessels possessed the best performance for identifying IDH1 mutations in gliomas(AUC:0.855,sensitivity:0.857,specificity:0.812,P<0.001).Conclusion The number of tumor blood vessels has comparable diagnostic performance with DCE-derived parameters for differentiating IDH1 mutations and can serve as a potential imaging biomarker to reflect IDH1 mutations in gliomas.展开更多
BACKGROUND Esophagogastric varices are a common complication of cirrhosis with portal hypertension and endoscopic treatment has been recognized as a primary preventive and therapeutic option for such patients;however,...BACKGROUND Esophagogastric varices are a common complication of cirrhosis with portal hypertension and endoscopic treatment has been recognized as a primary preventive and therapeutic option for such patients;however,it should be noted that bradyarrhythmia is regarded as one of the contraindications to endoscopic examination.Meanwhile,acute variceal bleeding may result in a high mortality rate in cirrhotic patients with portal hypertension accompanied by bradyarrhythmia.At present,there is an absence of reports concerning the treatment of such group of patients who underwent transjugular intrahepatic portosystemic shunt(TIPS).The present report details the case of a cirrhotic patient with acute variceal bleeding accompanied by bradyarrhythmia who underwent TIPS under temporary pacemaker protection.CASE SUMMARY We report the case of a 64-year-old male patient who was confirmed with bradyarrhythmia by ambulatory electrocardiogram 24 h before the operation.The patient was successfully treated by TIPS under temporary pacemaker protection.CONCLUSION In terms of cirrhotic patients with abnormal cardiac electrophysiological conduction,TIPS may be effective in reducing the complications of portal hypertension following the exclusion of severe pulmonary hypertension and heart failure,showing moderate feasibility in clinical applications.展开更多
BACKGROUND Congenital transmesenteric hernia in children is a rare and potentially fatal form of internal abdominal hernia,and no specific clinical symptoms can be observed preoperatively.Therefore,this condition is n...BACKGROUND Congenital transmesenteric hernia in children is a rare and potentially fatal form of internal abdominal hernia,and no specific clinical symptoms can be observed preoperatively.Therefore,this condition is not widely known among clinicians,and it is easily misdiagnosed,resulting in disastrous effects.CASE SUMMARY This report presents the case of a 13-year-old boy with a chief complaint of abdominal pain and vomiting and a history of duodenal ulcer.The patient was misdiagnosed with gastrointestinal bleeding and treated conservatively at first.Then,the patient’s symptoms were aggravated and he presented in a shock-like state.Computed tomography revealed a suspected internal hernia,extensive small intestinal obstruction,and massive effusion in the abdominal and pelvic cavity.Intraoperative exploration found a small mesenteric defect approximately 3.5 cm in diameter near the ileocecal valve,and there was about 1.8 m of herniated small intestine that was treated by resection and anastomosis.The patient recovered well and was followed for more than 5 years without developing short bowel syndrome.CONCLUSION In this report,we review the pathogenesis,presentation,diagnosis,and treatment of congenital transmesenteric hernia in children.展开更多
Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-san...Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-sandwich benzyl fluorenyl scandium complex 4 and pyridyl-methylene-fluorenyl rare-metal complexes 5a–5c. Complexes 1, 4 and 5a–5c show trans-1,2-regioselectivities and high activities, of which 5c exhibits excellent isoselectivity(mmmm>99%). Conversely, complexes 2 and 3 promote β-ocimene polymerization to produce isotactic cis-1,4-polyocimenes(cis-1,4>99%, mm>95%). Diblock copolymers cis-1,4-PIP-block-cis-1,4-POc and cis-1,4-PBD-block-cis-1,4-POc are obtained in one-pot reactions of β-ocimene with isoprene and butadiene using complex 3. Epoxidation and hydroxylation of polyocimene afford functionalized polyolefins with enhanced T_(g)(from-20 ℃ to 79 ℃ and 74 ℃) and hydrophilicity.展开更多
Background:We investigated the prognostic value of preoperative fibrinogen levels in hepatocellular carcinoma patients receiving liver transplantation by building a scoring model for predicting tumor recurrence.Method...Background:We investigated the prognostic value of preoperative fibrinogen levels in hepatocellular carcinoma patients receiving liver transplantation by building a scoring model for predicting tumor recurrence.Methods:Cox regression analysis was used to identify factors that predicted tumor recurrence,and a scoring model was generated by assigning a value of 0 or 1 to each independent risk factor.The cut-off value for fibrinogen was determined by receiver operating characteristic curve analysis.Results:Preoperative fibrinogen concentration was significantly higher in patients with vs.without tumor recurrence(3.27 g/L vs.2.34 g/L,P<0.001),with vs.without macrovascular invasion(3.54 g/L vs.2.82 g/L,P?0.007),and with>400 vs.400 ng/mL plasma alpha-fetoprotein concentration(3.43 g/L vs.2.76 g/L,P?0.007).The 5-year disease-free survival rate was significantly lower for patients with elevated(2.68 g/L)vs.normal(<2.68 g/L)fibrinogen concentration(37.2%vs.78.4%,P?0.001).Macrovascular invasion,>3 tumor nodules,and elevated fibrinogen concentration were independent risk factors for tumor recurrence.A scoring model based on these risk factors predicted recurrence with a sensitivity of 68.3%and a specificity of 87.5%.Conclusions:Elevated preoperative plasma fibrinogen concentration is associated with tumor recurrence in HCC patients after liver transplantation.A new scoring model predicted recurrence with good sensitivity and specificity.展开更多
Salt metathesis reactions between pyridyl-methylene-cyclopentadienyl lithium salt and LnCl_3 followed by the addition of two equivalents of LiCH_2SiMe_3 afforded a series of constrained-geometry-configuration rare-ear...Salt metathesis reactions between pyridyl-methylene-cyclopentadienyl lithium salt and LnCl_3 followed by the addition of two equivalents of LiCH_2SiMe_3 afforded a series of constrained-geometry-configuration rare-earth metal bis(alkyl) complexes(Cp′CH_2-Py)Ln(CH_2SiMe_3)_2(THF)_n(Py = C_5H_4N, Cp′ = C_5H_4(Cp), Ln = Sc, n = 0(1); Cp′ = C_9H_6(Ind), Ln = Sc, n = 0(2); Cp′ = 3-Me_3Si-C_9H_5(3-Me_3Si-Ind), Ln = Sc, n = 0(3a), Ln = Lu(3b), Y(3c), n = 1; Cp′ = 2,7-(~tBu)_2C_(13)H_8(2,7-(~tBu)_2-Flu), Ln = Sc(4 a), n = 0, Ln = Lu(4b),Y(4c), n = 1) in moderate to good yields, which were characterized by NMR spectroscopy and single-crystal X-ray diffraction(for complex 3a). In the presence of [Ph_3C][B(C_6F_5)_4] and Al^iBu_3, these complexes displayed different performances towards styrene polymerization. Rare-earth metal bis(alkyl) precursors bearing Cp, Ind, and 3-Me_3Si-Ind segments exhibited very low catalytic activity to afford syndiotactic polystyrene. All electron-donating t Bu substituted complexes 4 a, 4 b, and 4 c showed very high activity and perfect syndiotactivity(rrrr > 99%), producing high molecular weight polystyrene(up to 54.1 × 10~4) with relatively narrow molecular distribution(PDI = 1.28-2.49).展开更多
Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C...Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C_(6) F_(5))_(4)] and Ali Bu3 shows high cis-1,4-selectivity(>98%) for the polymerization of 2-XPB(2-XPB = 2-FPB, 2-Cl PB and 2-Br PB) to afford halogenated plastic poly(dienes) with glass transition temperatures of30–55 ℃. Moreover, the copolymerization of 2-XPB with isoprene(IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with ^(n)Bu Li, CO_(2) and HCl.展开更多
The catalytic performa nee of rare-earth metal dialkyl complexes in combi nation with DMAO(dry methylalumi no xane)is explored.In the presence of 60 equivalents of DMAO,the half-sandwich complex(C_(13)H_(8)CH_(2)Ph)Sc...The catalytic performa nee of rare-earth metal dialkyl complexes in combi nation with DMAO(dry methylalumi no xane)is explored.In the presence of 60 equivalents of DMAO,the half-sandwich complex(C_(13)H_(8)CH_(2)Ph)Sc(CH_(2)SiMe_(3))_(2)(THF)(1)is inert for styrene polymerization,but(C_(5)Me_(4)Ph)Sc(CH_(2)C_(6)H_(4)NMe_(2)-o)_(2)(2)con verts 18% styre ne into syn diotactic polystyrene.Under the same conditi ons,the con strained-geometry configuration sandium complex(C13H8CH2Py)Sc(CH_(2)SiMe_(3))_(2)(3a)displays extremely high catalytic activity(>6420 kg·mol_(sc)^(-1)h^(-1))and perfect syndiospecific(rrrr>99%)for styrene polymerization,while its lutetium(3b)and yttrium(3c)analogues are nearly inactive.Although the binary catalytic system 3a/DMAO exhibits very low activity for 4-methoxystyrene polymerization,it is an efficient catalyst for the syndioselective polymerization of other styrene derivatives such as 2-methoxystyrene,4-methylthiostyrene,4-fluorostyrene,4-dimethylhydrosilylstyrene,alkyne-susbstituted styrenes and 4-methylstyrene.In addition,the binary system 3a/DMAO can copolymerize ethylene and styrene to give alternating copolymers with a single glass tran sition at 80℃ and 0.4 MPa ethylene pressures.By in creasing styrene feed amount from 20 mmol to 60 mmol,the styre ne con tent slight in creases from 48.2 mol% to 53.8 mol%,but the polymerizatio n activity is obviously promoted from 240 kg·mol_(Sc)^(-1)·h^(-1) to 532 kg·mol_(sc)^(-1)·h^(-1).展开更多
基金Supported by National Natural Science Foundation of China,No.81372243,No.81570593 and No.81370575Key Scientific and Technological Projects of Guangdong Province,No.2014B020228003 and No.2014B030301041+2 种基金Natural Science Foundation of Guangdong Province,No.2015A030312013Science and Technology Planning Project of Guangzhou,No.201400000001-3,No.201508020262 and No.2014J4100128Science and Technology Planning Project of Guangdong Province,No.2017A020215178
文摘AIM To perform a meta-analysis on laparoscopic hepatectomy VS conventional liver resection for treating hepatolithiasis.METHODS We conducted a systematic literature search on Pub Med,Embase,Web of Science and Cochrane Library,and undertook a meta-analysis to compare the efficacy and safety of laparoscopic hepatectomy V S conventional open liver resection for local hepatolithiasis in the left or right lobe. Intraoperative and postoperative outcomes(time,estimated blood loss,blood transfusion rate,postoperative intestinal function recovery time,length of hospital stay,postoperative complication rate,initial residual stone,final residual stone and stone recurrence) were analyzed systematically.RESULTS A comprehensive literature search retrieved 16 publications with a total of 1329 cases. Meta-analysis of these studies showed that the laparoscopic approach for hepatolithiasis was associated with significantly less intraoperative estimated blood loss [weighted mean difference(WMD): 61.56,95% confidence interval(CI): 14.91-108.20,P = 0.01],lower blood transfusion rate [odds ratio(OR): 0.41,95%CI: 0.22-0.79,P = 0.008],shorter intestinal function recovery time(WMD: 0.98,95%CI: 0.47-1.48,P = 0.01),lower total postoperative complication rate(OR: 0.52,95%CI: 0.39-0.70,P < 0.0001) and shorter stay in hospital(WMD: 3.32,95%CI: 2.32-4.32,P < 0.00001). In addition,our results showed no significant differences between the two groups in operative time(WMD: 21.49,95%CI: 0.27-43.24,P = 0.05),residual stones(OR: 0.79,95%CI: 0.50-1.25,P = 0.31) and stone recurrence(OR: 0.34,95%CI: 0.11-1.08,P = 0.07). Furthermore,with subgroups analysis,our results proved that the laparoscopic approach for hepatolithiasis in the left lateral lobe and left side could achieve satisfactory therapeutic effects. CONCLUSION The laparoscopic approach is safe and effective,with less intraoperative estimated blood loss,fewer postoperative complications,reduced length of hospital stay and shorter intestinal function recovery time than with conventional approaches.
基金Science and Technology Planning Project of Guangzhou,No.201604020001
文摘AIM To perform a systematic review and meta-analysis on minimally vs conventional invasive techniques for harvesting grafts for living donor liver transplantation. METHODS PubMed, Web of Science, EMBASE, and the Cochrane Library were searched comprehensively for studies comparing MILDH with conventional living donor hepatectomy (CLDH). Intraoperative and postoperative outcomes (operative time, estimated blood loss, postoperative liver function, length of hospital stay, analgesia use, complications, and survival rate) were analyzed in donors and recipients. Articles were included if they: (1) compared the outcomes of MILDH and CLDH; and (2) reported at least some of the above outcomes. RESULTS Of 937 articles identified, 13, containing 1592 patients, met our inclusion criteria and were included in the meta-analysis. For donors, operative time [weighted mean difference (WMD) = 20.68, 95% CI: -6.25-47.60, p = 0.13] and blood loss (WMD = -32.61, 95% CI: -80.44-5.21, p = 0.18) were comparable in the two groups. In contrast, analgesia use (WMD = -7.79, 95% CI: -14.06-1.87, p = 0.01), postoperative complications [odds ratio (OR) = 0.62, 95% CI: 0.44-0.89, p = 0.009], and length of hospital stay (WMD): -1.25, 95% CI: -2.35-0.14, p = 0.03) significantly favored MILDH. No differences were observed in recipient outcomes, including postoperative complications (OR = 0.93, 95% CI: 0.66-1.31, p = 0.68) and survival rate (hr = 0.96, 95% CI: 0.27-3.47, p = 0.95). Funnel plot and statistical methods showed a low probability of publication bias. CONCLUSION MILDH is safe, effective, and feasible for living donor liver resection with fewer donor postoperative complications, reduced length of hospital stay and analgesia requirement than CLDH.
基金the National Natural Science Foundation of China(No.81730049 and No.81801666)the Fundamental Research Funds for the Central Universities,HUST(No.2019JYCXJJ044).
文摘Objective Isocitrate dehydrogenase gene(IDH)mutations are associated with tumor angiogenesis and therefore play an important role in glioma management.This study compared the performance of tumor blood vessels counted from contrast-enhanced 3D brain volume(3D-BRAVO)sequence and dynamic contrast-enhanced(DCE)MRI in differentiating IDH1 status in gliomas.Methods Forty-four glioma patients[16 with IDH1 mutant-type(IDH1-MT),28 with IDH1 wild-type(IDH1-WT)]were retrospectively analyzed.A blood vessel entering a tumor was defined as an intratumoral vessel;a blood vessel adjacent to the edge of a tumor was defined as a peritumoral vessel.Combined vessels were defined as the sum of the intratumoral and peritumoral vessels.DCE-derived metrics of tumor were normalized to the contralateral normal-appearing white matter.Results Intratumoral,peritumoral,and combined tumor blood vessels were all significantly different between IDH1-MT and IDH1-WT gliomas,and the range of area under curves(AUCs)was 0.816–0.855.For DCE-derived parameters,cerebral blood volume,cerebral blood flow,mean transit time,and volume transfer constant were significantly different between IDH1-MT and IDH1-WT gliomas,and the range of AUCs was 0.703–0.756.Combined vessels possessed the best performance for identifying IDH1 mutations in gliomas(AUC:0.855,sensitivity:0.857,specificity:0.812,P<0.001).Conclusion The number of tumor blood vessels has comparable diagnostic performance with DCE-derived parameters for differentiating IDH1 mutations and can serve as a potential imaging biomarker to reflect IDH1 mutations in gliomas.
文摘BACKGROUND Esophagogastric varices are a common complication of cirrhosis with portal hypertension and endoscopic treatment has been recognized as a primary preventive and therapeutic option for such patients;however,it should be noted that bradyarrhythmia is regarded as one of the contraindications to endoscopic examination.Meanwhile,acute variceal bleeding may result in a high mortality rate in cirrhotic patients with portal hypertension accompanied by bradyarrhythmia.At present,there is an absence of reports concerning the treatment of such group of patients who underwent transjugular intrahepatic portosystemic shunt(TIPS).The present report details the case of a cirrhotic patient with acute variceal bleeding accompanied by bradyarrhythmia who underwent TIPS under temporary pacemaker protection.CASE SUMMARY We report the case of a 64-year-old male patient who was confirmed with bradyarrhythmia by ambulatory electrocardiogram 24 h before the operation.The patient was successfully treated by TIPS under temporary pacemaker protection.CONCLUSION In terms of cirrhotic patients with abnormal cardiac electrophysiological conduction,TIPS may be effective in reducing the complications of portal hypertension following the exclusion of severe pulmonary hypertension and heart failure,showing moderate feasibility in clinical applications.
基金Zhejiang Province Public Welfare Technology Application Research Project,No.LGF21H160022and Project of Taizhou Central Hospital,No.2019KT003.
文摘BACKGROUND Congenital transmesenteric hernia in children is a rare and potentially fatal form of internal abdominal hernia,and no specific clinical symptoms can be observed preoperatively.Therefore,this condition is not widely known among clinicians,and it is easily misdiagnosed,resulting in disastrous effects.CASE SUMMARY This report presents the case of a 13-year-old boy with a chief complaint of abdominal pain and vomiting and a history of duodenal ulcer.The patient was misdiagnosed with gastrointestinal bleeding and treated conservatively at first.Then,the patient’s symptoms were aggravated and he presented in a shock-like state.Computed tomography revealed a suspected internal hernia,extensive small intestinal obstruction,and massive effusion in the abdominal and pelvic cavity.Intraoperative exploration found a small mesenteric defect approximately 3.5 cm in diameter near the ileocecal valve,and there was about 1.8 m of herniated small intestine that was treated by resection and anastomosis.The patient recovered well and was followed for more than 5 years without developing short bowel syndrome.CONCLUSION In this report,we review the pathogenesis,presentation,diagnosis,and treatment of congenital transmesenteric hernia in children.
基金financially supported by the open research fund program of Science and Technology on Aerospace Chemical Power Laboratory (No. STACPL120221B03)the National Natural Science Foundation of China (Nos. s22175059,52073275 and U21A20279)。
文摘Coordination polymerization of renewable β-ocimene has been investigated using asymmetric diiminophosphinate lutetium complex1, β-diketiminate yttrium complex 2, bis(phosphino)carbazolide yttrium complex 3, half-sandwich benzyl fluorenyl scandium complex 4 and pyridyl-methylene-fluorenyl rare-metal complexes 5a–5c. Complexes 1, 4 and 5a–5c show trans-1,2-regioselectivities and high activities, of which 5c exhibits excellent isoselectivity(mmmm>99%). Conversely, complexes 2 and 3 promote β-ocimene polymerization to produce isotactic cis-1,4-polyocimenes(cis-1,4>99%, mm>95%). Diblock copolymers cis-1,4-PIP-block-cis-1,4-POc and cis-1,4-PBD-block-cis-1,4-POc are obtained in one-pot reactions of β-ocimene with isoprene and butadiene using complex 3. Epoxidation and hydroxylation of polyocimene afford functionalized polyolefins with enhanced T_(g)(from-20 ℃ to 79 ℃ and 74 ℃) and hydrophilicity.
基金supported by Science and Technology Planning Project of Guangdong Province,China(2017B020209004)Major State Research Development Program of China(2017ZX10203205-006-001,2017ZX10203205-001-003).
文摘Background:We investigated the prognostic value of preoperative fibrinogen levels in hepatocellular carcinoma patients receiving liver transplantation by building a scoring model for predicting tumor recurrence.Methods:Cox regression analysis was used to identify factors that predicted tumor recurrence,and a scoring model was generated by assigning a value of 0 or 1 to each independent risk factor.The cut-off value for fibrinogen was determined by receiver operating characteristic curve analysis.Results:Preoperative fibrinogen concentration was significantly higher in patients with vs.without tumor recurrence(3.27 g/L vs.2.34 g/L,P<0.001),with vs.without macrovascular invasion(3.54 g/L vs.2.82 g/L,P?0.007),and with>400 vs.400 ng/mL plasma alpha-fetoprotein concentration(3.43 g/L vs.2.76 g/L,P?0.007).The 5-year disease-free survival rate was significantly lower for patients with elevated(2.68 g/L)vs.normal(<2.68 g/L)fibrinogen concentration(37.2%vs.78.4%,P?0.001).Macrovascular invasion,>3 tumor nodules,and elevated fibrinogen concentration were independent risk factors for tumor recurrence.A scoring model based on these risk factors predicted recurrence with a sensitivity of 68.3%and a specificity of 87.5%.Conclusions:Elevated preoperative plasma fibrinogen concentration is associated with tumor recurrence in HCC patients after liver transplantation.A new scoring model predicted recurrence with good sensitivity and specificity.
基金financially supported by the National Natural Science Foundation of China (Nos. 51773193 and 21634007)department of science and technology of Jilin province (No.20180101171JC)the "973" project (No. 2015CB654702)
文摘Salt metathesis reactions between pyridyl-methylene-cyclopentadienyl lithium salt and LnCl_3 followed by the addition of two equivalents of LiCH_2SiMe_3 afforded a series of constrained-geometry-configuration rare-earth metal bis(alkyl) complexes(Cp′CH_2-Py)Ln(CH_2SiMe_3)_2(THF)_n(Py = C_5H_4N, Cp′ = C_5H_4(Cp), Ln = Sc, n = 0(1); Cp′ = C_9H_6(Ind), Ln = Sc, n = 0(2); Cp′ = 3-Me_3Si-C_9H_5(3-Me_3Si-Ind), Ln = Sc, n = 0(3a), Ln = Lu(3b), Y(3c), n = 1; Cp′ = 2,7-(~tBu)_2C_(13)H_8(2,7-(~tBu)_2-Flu), Ln = Sc(4 a), n = 0, Ln = Lu(4b),Y(4c), n = 1) in moderate to good yields, which were characterized by NMR spectroscopy and single-crystal X-ray diffraction(for complex 3a). In the presence of [Ph_3C][B(C_6F_5)_4] and Al^iBu_3, these complexes displayed different performances towards styrene polymerization. Rare-earth metal bis(alkyl) precursors bearing Cp, Ind, and 3-Me_3Si-Ind segments exhibited very low catalytic activity to afford syndiotactic polystyrene. All electron-donating t Bu substituted complexes 4 a, 4 b, and 4 c showed very high activity and perfect syndiotactivity(rrrr > 99%), producing high molecular weight polystyrene(up to 54.1 × 10~4) with relatively narrow molecular distribution(PDI = 1.28-2.49).
基金financially supported by the National Natural Science Foundation of China (Nos. 21634007 and 51773193)the Department of Science and Technology of Jilin Province(No. 20180101171JC)。
文摘Polymerization of 2-(4-halophenyl)-1,3-butadiene(2-XPB) and their copolymerization with isoprene using a yttrium catalyst have been examined. The β-diketiminato yttrium bis(alkyl) complex(1) activated by [Ph_3 C][B(C_(6) F_(5))_(4)] and Ali Bu3 shows high cis-1,4-selectivity(>98%) for the polymerization of 2-XPB(2-XPB = 2-FPB, 2-Cl PB and 2-Br PB) to afford halogenated plastic poly(dienes) with glass transition temperatures of30–55 ℃. Moreover, the copolymerization of 2-XPB with isoprene(IP) has also been achieved by this catalyst, and the insertion ratios of 2-XPB can be facilely tuned in a full range of 0%–100% simply by changing the 2-XPB-to-IP ratio. Quantitative hydrogenation of cis-1,4-poly(2-XPB) results in perfect alternating ethylene-halostyrene copolymers, and an alternating copolymer of 4-vinylbenzoic acid with ethylene is obtained by a consecutive reaction of ethylene-4-bromostyrene copolymer with ^(n)Bu Li, CO_(2) and HCl.
基金This work was partially financially supported by the National Natural Science Foundation of China(Nos.51773193 and 52073275).
文摘The catalytic performa nee of rare-earth metal dialkyl complexes in combi nation with DMAO(dry methylalumi no xane)is explored.In the presence of 60 equivalents of DMAO,the half-sandwich complex(C_(13)H_(8)CH_(2)Ph)Sc(CH_(2)SiMe_(3))_(2)(THF)(1)is inert for styrene polymerization,but(C_(5)Me_(4)Ph)Sc(CH_(2)C_(6)H_(4)NMe_(2)-o)_(2)(2)con verts 18% styre ne into syn diotactic polystyrene.Under the same conditi ons,the con strained-geometry configuration sandium complex(C13H8CH2Py)Sc(CH_(2)SiMe_(3))_(2)(3a)displays extremely high catalytic activity(>6420 kg·mol_(sc)^(-1)h^(-1))and perfect syndiospecific(rrrr>99%)for styrene polymerization,while its lutetium(3b)and yttrium(3c)analogues are nearly inactive.Although the binary catalytic system 3a/DMAO exhibits very low activity for 4-methoxystyrene polymerization,it is an efficient catalyst for the syndioselective polymerization of other styrene derivatives such as 2-methoxystyrene,4-methylthiostyrene,4-fluorostyrene,4-dimethylhydrosilylstyrene,alkyne-susbstituted styrenes and 4-methylstyrene.In addition,the binary system 3a/DMAO can copolymerize ethylene and styrene to give alternating copolymers with a single glass tran sition at 80℃ and 0.4 MPa ethylene pressures.By in creasing styrene feed amount from 20 mmol to 60 mmol,the styre ne con tent slight in creases from 48.2 mol% to 53.8 mol%,but the polymerizatio n activity is obviously promoted from 240 kg·mol_(Sc)^(-1)·h^(-1) to 532 kg·mol_(sc)^(-1)·h^(-1).
