Installation and performance of horizontal wells for dewatering at municipal solid waste landfills in China.

Vertical wells are conventionally used to lower leachate levels or pressures in municipal solid waste (MSW) landfills. However, they are not always efficient or even effective, and in some circumstances retro-fitted horizontal wells represent a potential alternative. However, horizontal wells can be difficult to install and there is a lack of data on their performance. This paper describes the trial construction and operation of three horizontal wells in a landfill at Tianziling, China. The trial was used to develop an improved well installation technique, and to demonstrate the viability of the approach in a typical Chinese landfill. Three wells, between 50 m and 56 m in length, were successfully installed using an improved casing-protected directional drilling method. Average leachate flow rates of two wells were 10.66 m3/day and 3.93 m3/day, respectively. After 74 days of drainage, the maximum leachate level drawdown around the highest flow well was 2.7 m and its distance of influence was up to 50 m. Building on the experience gained at Tianziling, a wellfield comprising twelve horizontal wells having a total length of 1000 m was installed at Xingfeng landfill. After 157 days of drainage, a total volume of ~24,000 m3 leachate had been discharged and the leachate level had been lowered to near the elevation of the horizontal wells. This paper indicates the effectiveness of horizontal wells in reducing leachate level in landfills containing MSW typical of that generated in China, and gives data on installation and performance that may be useful for the design and operation of such an approach.

Lignans from the fruit of Schisandra glaucescens with antioxidant and neuroprotective properties.

Two rare 7,8-seco-lignans (1, 2), three new lignan glycosides (3, 4a, 4b), and 10 known lignans (5-14) were isolated from the fruit of Schisandra glaucescens Diels. The absolute configurations of 1 and 2 were determined by comparing their experimental and calculated electronic circular dichroism spectra. The molecular structures of the new compounds (3, 4a, and 4b), including their absolute configurations, were determined using various spectroscopic methods and hydrolysis reactions. The antioxidant activities of the isolated compounds were tested using 2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays. Compounds 4, 7, 8, 10, 11, and 12 exhibited antioxidant activities of varying potential in both assays. Of these compounds, 7 showed the strongest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, with IC50 values of 15.7 (150 µM DPPH) and 34.6 µM (300 µM DPPH), respectively, and 4, 12, and 7 displayed higher total antioxidant activities than Trolox in the ferric reducing antioxidant power assay. The neuroprotective effects of these compounds against Aß25-35-induced cell death in SH-SY5Y cells were also investigated. Compounds 1, 2, 6, 7, 8, 11, and 12 exhibited statistically significant neuroprotective effects against Aß25-35-induced SH-SY5Y cell death compared with the group treated only with Aß25-35.

Core-shell structure microcapsules with dual pH-responsive drug release function.

We report dual pH-responsive microcapsules manufactured by combining electrostatic droplets (ESD) and microfluidic droplets (MFD) techniques to produce monodisperse core (alginate)-shell (chitosan) structure with dual pH-responsive drug release function. The fabricated core-shell microcapsules were size controllable by tuning the synthesis parameters of the ESD and MFD systems, and were responsive in both acidic and alkaline environment, We used two model drugs (ampicillin loaded in the chitosan shell and diclofenac loaded in the alginate core) for drug delivery study. The results show that core-shell structure microcapsules have better drug release efficiency than respective core or shell particles. A biocompatibility test showed that the core-shell structure microcapsules presented positive cell viability (above 80%) when evaluated by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results indicate that the synthesized core-shell microcapsules were a potential candidate of dual-drug carriers.

Neuroprotective lignans from the stems of Schisandra glaucescens.

Two new tetrahydrofuran lignans, schiglaucin A and B (1-2), together with eight known analogues (3-10), were isolated from the stems of Schisandra glaucescens Diels. Their structures were elucidated on the basis of spectroscopic techniques (HRESIMS, UV, IR, NMR, and CD experiments). All of the compounds were tested for their neuroprotective activities against H2O2- and CoCl2-induced cell injuries in SH-SY5Y cells, respectively. Compounds 1-10 showed significant neuroprotective effects against H2O2-induced SH-SY5Y cell death, while compounds 1-5 and 8-10 exhibited significant neuroprotective effects against CoCl2-induced SH-SY5Y cell injury.