“拼凑式合作”:资源约束下基层治理的“权宜之计”?

合作治理是否只是主体间的合作?为了把支撑合作的非主体要素纳入基层治理分析范畴,揭开合作治理的过程黑箱,论文首先将合作治理的本质界定为资源的合作,接着引入拼凑理论,探究G市3个城乡社区资源拼凑的共性机制,进而讨论由此产生的“拼凑式合作”究竟是资源约束下基层治理的“权宜之计”还是“长久之计”。研究发现,积分驱动下的治理资源拼凑行为由制度拼凑、人力拼凑、场景拼凑、金融拼凑、市场拼凑构成,其内部存在的补缺关系、互构关系和紧张关系共同形塑出G市资源拼凑的复杂机制。在此基础上,论文借助共生理论评估合作效果,通过案例的横向比较,指出依靠单一主体提供资源的偏利共生型“拼凑式合作”,可能陷入治理资源耗竭的窘境,是资源约束下基层治理的“权宜之计”;而强调治理资源内外互补、循环互动的互惠共生型“拼凑式合作”,成为基层治理的“长久之计”,为理解合作治理提供了一种新的视角。

走进奇妙的分子聚集态世界——渗透扩散及表面张力的魅力

化学世界丰富多彩。认识多姿、多彩的材料形成过程,揭示产物生成的奥秘,通过对宏观化学现象的观察,推测产物生长的微观过程,增强学生对化学的学习兴趣,是化学实验教学的主要目的之一。本实验以“界面反应”为切入点,以多彩多姿分子聚集体为目标产物,通过自主设计的反应器,以多孔陶瓷砂芯为隔离层,利用渗透和扩散效应、表面张力及界面反应机理,在砂芯表面可控形成白色、蓝色、绿色、粉色等多彩中空纤维状及珊瑚礁状等多姿的分子聚集体。本科普实验方法安全、新颖、简单,现象明显,具有很高的观赏性,旨在达到在探索微观世界形成过程中发现化学无穷魅力,认识“美丽化学”“奇妙化学”的真实内涵,激发学生对化学学科学习热情之目的。

Assessing the impacts of ecological-living-productive land changes on eco-environmental quality in Xining City on Qinghai-Tibet Plateau, China

The Ecological-living-productive land(ELPL)classification system was proposed in an effort to steer China's land pattern to an ecological-centered path,with the development model shifting from a single function into more integrated multifunction land use.The focus is coordinating the man-land contradictions and developing an intensive,efficient and sustainable land use policy in an increasingly tense relationship between humans and nature.Driven by socioeconomic change and rapid population growth,many cities are undergoing urban sprawl,which involves the consumption of cropland and ecological land and threatens the ecological balance.This paper aims to quantitatively analyze the critical effects of ELPL changes on eco-environmental quality according to land use classification based on leading function of ecology,living and production from 1990 to 2015 with a case study of Xining City.Also,four future land use scenarios were simulated for 2030 using the Future Land Use Simulation(FLUS)model that couples human and natural effects.Our results show a decrease in productive land(PL)and an increase in ecological land(EL)and living land(LL)in Xining City.Forestry ecological land(FEL)covered the top largest proportion;agriculture productive land(APL)showed the greatest reduction and urban and rural living land(U-RLL)presented a dramatic increase.The eco-environmental quality improved in 1990-2010,mainly affected by the conversion of APL to FEL and GEL.However,the encroachment of U-RLL into APL,other ecological land(OEL)and FEL was the main contributor to the decline in eco-environmental quality in 2010-2015 as well as the primary reason for the increase area of lower-quality.The Harmonious Development(HD)-Scenario,characterized by a rational allocation of LL and PL and a better eco-environment,would have implications for planning and monitoring future management of ELPL,and may represent a valuable reference for local policy-makers.

Catalytic transfer hydrogenation of levulinate ester intoγ-valerolactone over ternary Cu/ZnO/Al2O3 catalyst

An effective catalytic transfer hydrogenation (CTH) process of bio-based levulinate esters into γ-valerolactone (GVL) was explored over ternary Cu/ZnO/Al2O3 catalyst which was prepared by coprecipitation method and could be sustainably used. As a result, quantitative conversion of ethyl levulinate (EL) and 99.0% yield of GVL were obtained in the CTH process using i-PrOH as hydrogen donor. The Cu/ZnO/Al2O3 catalyst with high-surface-area could be reused at least four times without the loss of catalytic activity. Furthermore, the structure and properties of Cu/ZnO/Al2O3 catalyst was characterized through XRD, BET, SEM, TEM and H2-TPR. Also, the influence of different support oxides and calcination temperatures was investigated.

The storage mechanism difference between amorphous and anatase as supercapacitors

Although TiO_(2)nanotubes is a promising electrode as supercapacitors due to its high energy density,easy synthesis and chemical stability,there are draw backs such as low conductivity and capacitance.Many studies concentrated on improving its electrochemical performance itself but little attention was payed to the reason of capacitance differences caused by its different crystal structures.Herein,we prepare amorphous and anatase TiO_(2)nanotubes and hydrogenated them by a simple electrochemical hydrogenation method to improve their conductivity and capacitance.And then study and compare their morphology and structure differences by SEM,TEM,XRD and BET.The results show that the pore size distribution,internal structure order and internal carrier concentration are the main reasons for their electrochemical performance differences.The microporous structure less than 2 nm in amorphous nanotubes act as a trap of electrolyte ions at current density larger than 0.1μA cm^(-2),leading to small charge and discharge capacitance.The long-range ordered crystal structure of anatase is more favorable for the orderly diffusion of carriers,reducing the inelastic scattering of carrier diffusion process and the electron hole-complexing probability,making anatase nanotubes exhibit higher coulomb efficiency and cycle stability than that of amorphous ones.

Enhancing solar-driven overall water splitting via both sacrifice and noble metal free photocatalysis: copper cluster/boron-doped carbon nitride catalysts

The major impediment to the additional industrialization of water splitting is the high cost of the co-catalyst made of noble metals and the sacrificial reagent. A binary photocatalytic system, consisting of B-doped g-C_(3)N_(4) nanosheets(Cu_(20)@BCN-X) and atomically accurate copper clusters, is designed in this study. The copper clusters serve as co-catalysts for H_(2) evolution and exhibit Pt-like activity, whereas the nanosheets serve as carriers and semiconductor components for O_(2) evolution. Such binary system, created using simple techniques, demonstrates hydrogen bonding interactions that promote synergistic effects and efficient binding and charge transfer across the interface between the two components. Band position manipulation of carbon nitride nanosheets demonstrates a Z-scheme charge transfer mechanism between the nanosheets and copper clusters. This photocatalytic system can accomplish the photocatalytic overall water splitting process(259.9 μmol g^(-1)h^(-1)of H_(2) and 129.4 μmol g^(-1)h^(-1)of O_(2)) without using sacrificial agents or noble metal co-catalysts. This work lays the foundation for the design of overall water splitting catalysts by precisely manipulating the energy levels, and it also paves the way for commercialized photocatalytic catalysts that do not require noble metals or sacrificial chemicals.

A novel point source oxygen supply method for sleeping environment improvement at high altitudes

The hypoxic environment at high altitudes causes various sleep disorders.Diffuse oxygen enrichment is an effective way to alleviate sleep disorders and improve the built environment in high altitude areas.In this study,a novel point source local diffuse oxygen supply method was proposed to improve the sleeping oxygen environment.The oxygen supply performance was investigated by the computational fluid dynamics(CFD)method including the oxygen concentration and air velocity distributions.A sleeping experiment was conducted on the plateau to validate the CFD model.The occupied zone including the inhalation zone and the active zone was defined.The results showed that the oxygen concentration showed a rapid rise,then decreased slowly,and finally tended to be stable.The oxygen concentration after stabilization was remarkably influenced by indoor ventilation rate.The sleeping environment’s improvement was examined considering the oxygen enrichment efficiency,uniformity,stability and human comfort demand.The optimal strategies were recommended with a ventilation rate of 1 air change per hour,supplied oxygen concentration of 90%;and jet distance of 0.50 m.The study contributes to improving the oxygen environment and human sleep quality in an effective and energy-saving approach to the sustainable development of buildings in high altitude areas.

Ultrahigh detectivity,high-speed and low-dark current AlGaN solar-blind heterojunction field-effect phototransistors realized using dual-float-photogating effect

High detectivity is essential for solar-blind deep-ultraviolet(DUV)light detection because the DUV signal is extremely weak in most applications.In this work,we report ultrahigh-detectivity AlGaN-based solar-blind heterojunction-field-effect phototransistors fabricated utilizing dual-float-photogating effect.The p^(+)-Al_(0.4)GaN layer and Al_(0.4)GaN absorber layer deposited on the Al_(0.6)GaN barrier serve as top pin-junction photogate,while the thin Al_(0.4)GaN channel layer with a strong polarization field inside acts as virtual back photogate.Due to the effective depletion of the two-dimensional electron gas at the A1_(0.6)Ga_(0.4)N/Al_(0.4)Ga_(0.6)N heterointerface by the top photogate,the dark current was suppressed below 2 pA in the bias range of 0 to 10 V.A high photo-to-dark current ratio over 10^(8) and an optical gain of 7.5×10^(4) were demonstrated at a bias of 5 V.Theoretical analysis indicates that the optical gain can be attributed to the joint action of the floating top and back photogates on the channel current.As a result,a record high flicker noise(Johnson and shot noise)limited specific detectivity of 2.84×10^(15)(2.91×10^(17))cm Hz^(0.5)W^(-1) was obtained.Furthermore,high response speed at the microsecond level was also shown in the devices.This work provides a promising and feasible approach for high-sensitivity DUV detection.