经济补偿对耕地非农转换的抑制成效检验——以成都市耕地保护基金的准自然实验为例证

以成都市耕地保护基金的准自然实验为例证,根据2005~2018年LUCC遥感监测数据及社会经济数据,运用PSM-DID方法估算补偿政策对耕地非农转换的抑制效果。研究结果表明:经济补偿政策的实施能显著抑制耕地非农转换,这一结论在稳健性检验后依然成立。并且,随着政策的持续实施,耕地非农抑制成效逐渐显化。特别在抑制耕地向城镇用地转换方面起到重要作用,同时避免更多耕地转换为农村居民点,但对交通道路、机场等其他建设用地增长的抑制成效不明显。建议总结补偿试点经验,加快推进耕地保护补偿机制建设,同时,提高耕地保护在地方政府政绩考核中的地位,调动耕地保护内在激励。

Combined inhibitors of angiogenesis and histone deacetylase:Efficacy in rat hepatoma

AIM:To evaluate the antitumoral effect of combined inhibitors of angiogenesis and histone deacetylases in an experimental rat hepatoma model.METHODS:MH7777A hepatoma cells were injected into the liver of male Buffalo rats.After 7 d treatment with the vascular endothelial growth factor receptor antagonist PTK787/ZK222584(PTK/ZK),the histone deacetylase inhibitor MS-275,tamoxifen(TAM) and/or retinoic acid was initiated(n ≥ 8 animals/group).Natural tumor development was shown in untreated control groups(control 1 with n = 12,control 2 with n = 8).The control groups were initiated at different time points to demonstrate the stability of the hepatoma model.For documentation of possible side effects,we documented any change in body weight,loss of fur and diarrhea.After 21 d treatment,the rats were euthanized.Main target parameters were tumor size and metastasis rate.Additionally,immunohistochemistry for the proliferating cell nuclear antigen(PCNA) and TdT-mediated dUTP-biotin nick end labeling(TUNEL) assay were performed.RESULTS:The control groups developed large tumor nodules with extrahepatic tumor burden in the lung and abdominal organs(control 1:6.18 cm3 ± 4.14 cm3 and control 2:8.0 cm3 ± 4.44 cm3 28 d after tumor cell injection).The tumor volume did not differ significantly in the control groups(P = 0.13).As single agents MS-275 and PTK/ZK reduced tumor volume by 58.6% ± 2.6% and 48.7% ± 3.2% vs control group 1,which was significant only for MS-275(P = 0.025).The combination of MS-275 and PTK/ZK induced a nearly complete and highly significant tumor shrinkage by 90.3% ± 1%(P = 0.005).Addition of TAM showed no further efficacy,while quadruple therapy with retinoic acid increased antitumoral efficacy(tumor reduction by 93 ± 1%) and side effects.PCNA positive cells were not significantly reduced by the single agents,while dual therapy(MS-275 and PTK/ZK) and quadruple therapy reduced the PCNA-positive cell fraction significantly by 9.1 and 20.6% vs control 1(P < 0.05).The number of TUNEL-positive cells,markers for ongoing apoptosis,was increased significantly by the single agents(control 1:6.9%,PTK/ZK:11.4%,MS-275:12.2% with P < 0.05 vs control 1).The fraction of TUNEL-positive cells was upregulated highly significantly by dual therapy(18.4%) and quadruple therapy(24.8%,P < 0.01 vs control 1).For the proliferating(PCNA positive) and apoptotic cell fraction,quadruple therapy was significantly superior to dual therapy(P = 0.01).CONCLUSION:Combined PTK/ZK and MS-275 were highly effective in this hepatoma model.Quadruple therapy enhanced the effects microscopically,but not macroscopically.These results should be investigated further.

Super-aligned films of sub-1 nm Bi_(2)O_(3)-polyoxometalate nanowires as interlayers in lithiumsulfur batteries

Sub-1 nm nanowires(SNWs) can not only be processed like polymers due to their polymer-analogue properties but also show multifunctions owing to their well-manipulated compositions and structures. Rationally designed and engineered multicomponent heterostructure SNWs can further enhance their multifunction performance while it is very challenging to achieve such SNWs at sub-nanoscale.Herein, we synthesized Bi_(2)O_(3)-polyoxometalate heterostructure SNWs(PMB SNWs), and fabricated super-aligned PMB SNWs films(S-PMB SNWs films), which can serve as interlayers to efficiently suppress lithium polysulfide(LPS)shuttling, intrinsically promote the redox kinetics of the LPS conversion and substantially protect the Li anode. The lithium-sulfur(Li-S) battery with the S-PMB SNWs film as the interlayer showcases an ultralow capacity decay rate with 0.013% per cycle over 850 cycles. This study demonstrates the potential of heterostructure SNWs to improve the performance of Li-S batteries.