现场发生次氯酸钠-减少三氯甲烷浓度的关键？

使用氯气用作消毒处理引起了许多饮用水使用可能的处理和安全问题。近些年,随着阶段1消毒副产物章程（阶段1 DBPR）的制定,与TTHMs有关的问题正在逐渐增加。这些问题将可能加速阶段2消毒副产物章程（阶段2DBPR）的定案,导致许多使用氯气的设备寻找可替代的消毒方法。联合使用氯或氯胺已经广泛地被选择为替代方法用于消毒控制,但是,     

Subtelomeric sequence from the right arm of Schizosaccharomyces pombe chromosome I contains seven permease genes

The sequence has been determined of 80 888 bp of contiguous subtelomeric DNA, including the isp5 gene, from the right arm of chromosome I of Schizosaccharomyces pombe; 27 open reading frames (ORFs) longer than 100 codons are present, giving a density of one gene per 3.0 kb. Seven of the predicted proteins are members of the major facilitator superfamily (MFS) of transport proteins, including four amino acid permease homologues, bringing this family of amino acid permease sequences to 17 in Sz. pombe, and a phylogenetic analysis is presented. Also encoded is an allantoate permease homologue, a sulphate permease homologue and a probable urea active transporter. Predicted non-membrane proteins include a 1-aminocyclopropane-1-carboxylate deaminase (ACC deaminase), a class III aminotransferase, serine acetyltransferase, protein-L-isoaspartate O-methyltransferase, alpha-glucosidase, alpha-galactosidase, esterase/lipase, oxidoreductase of the short-chain dehydrogenase/reductase (SDR) family, aldehyde dehydrogenase, formamidase, amidase, flavohaemoprotein, a putative translation initiation inhibitor and a protein with similarity to a filamentous fungal conidiation-specific protein. The remaining six ORFs are likely to encode proteins, either because they have sequence similarity with hypothetical proteins or because they are known to be transcribed. Introns are scarce in the sequenced region: only three ORFs contain introns, with only one having multiple introns. The sequenced region also contains a single Tf1 transposon long terminal repeat (LTR). The sequence is derived from cosmid clones c869, c922 and c1039 and has been submitted to the EMBL database under entries SPAC869 (Accession No. AL132779), SPAC922 (AL133522) and SPAC1039 (AL133521).     

Statewide investigation of the role of pyrethroid pesticides in sediment toxicity in California's urban waterways

A statewide investigation of urban creek sediment toxicity was conducted in California in recognition of increased incidences of toxicity linked to pyrethroid pesticides. The goals were to examine the spatial occurrence and magnitude of sediment toxicity in California urban creeks, and to examine the role of pyrethroids in toxic urban creek sediment samples. After a preliminary screening of 90 sites, 30 creeks were sampled in eight geographical regions. Sediment toxicity was assessed using 10 day bioassays with the resident amphipod Hyalella azteca. Bioassays were conducted at two test temperatures of 23 degrees C and at 15 degrees C to provide evidence of the cause of toxicity, and to more accurately reflect ambient environmental temperatures. Twenty-five of 30 samples were toxic when tested at 23 degrees C, and all 30 samples were toxic when tested at 15 degrees C. The magnitude of toxicity increased in samples tested at 15 degrees C suggesting the influence of pyrethroids, which are more toxic at colder temperatures. Pyrethroids were present in all sediment samples and were the only compounds detected at concentrations toxic to H. azteca. Bifenthrin was the pyrethroid of greatest toxicological concern, occurring in all 30 samples at concentrations up to 219 ng/g. Pyrethroid contamination of urban creeks was most severe in the Los Angeles, Central Valley, and San Diego regions, respectively. However, pyrethroids were also linked to urban creek aquatic toxicity in all regions sampled, including the less urbanized areas of the North Coast and Lake Tahoe.     

Gold Nitride: Preparation and Properties

We review the currently known methods of producing gold nitride and report on the influence of electrically isolated substrates on the growth of gold nitride films by reactive ion sputtering (RIS). It is found that isolation of the substrate decreases grain size and increases nitrogen content, the latter attributed to longer nitrogen ion lifetime on the surface of the growing film. The chemical reactivity of gold nitride is compared with that of pure gold films using the adsorption of 1-dodecyl mercaptan (CH₃(CH₂)₁₁SH) as a model system and it is found that there is no significant difference between gold films and gold nitride in terms of Au–S binding. However, gold nitride nanoparticles are suggested to be worthy of further investigation in terms of their catalytic properties.

Impact of Storm-Water Runoff on Clogging and Fecal Bacteria Reduction in Sand Columns

Storm-water runoff has been identified as a major cause of coastal water quality degradation. Storm-water outfalls, common in many coastal towns, convey bacteria and other pollutants into the ocean and estuaries. In an effort to minimize this impact, the Town of Kure Beach, North Carolina, installed Dune Infiltration Systems (DIS) at two storm-water outfalls to receive storm-water runoff and allow infiltration beneath the beach dunes. A laboratory column experiment was performed to supplement this installation and determine the potential hydraulic and bacterial removal efficiency of the sand comprising the Kure Beach dunes. Columns constructed using sand collected at different depths of the dune were used to analyze the affect of bacteria application on infiltration and to examine the changes in bacteria removal that occur as infiltration rates are affected by bacteria-laden water application. Sand columns were loaded over a 60-day period with either bacteria-free storm water or storm water spiked with Escherichia coli. The seepage rate for the bacteria-spiked storm-water treatment was significantly lower (p<0.05) than the seepage rate of the bacteria-free treatment, particularly toward the end of the study. Bacteria application likely compounds the impact of sediment clogging at the sand/storm-water interface. This study indicates the need for maintenance when implementing a DIS or similar sand filter to maintain design infiltration rates, especially if reduced infiltration rates are not planned for in the design. However, a decrease in seepage rate was correlated with a decrease in effluent bacteria concentration in the bacteria-spiked storm-water sand columns. Thus, optimization is required to provide maximum infiltration of storm-water while maintaining bacteria removal efficiency.     

CARBON FROM PERIPHYTON SUPPORTS FISH BIOMASS IN WATERHOLES OF A WET–DRY TROPICAL RIVER

The identification of the dominant sources of carbon supporting consumer biomass in aquatic food webs is often difficult but essential to understanding the limits to aquatic secondary production. Stable isotope analysis (SIA) is a powerful tool to estimate the contribution of different sources to consumers, but most food web studies using this approach limit analyses to a few key consumer taxa rather than measuring biomass‐weighted contribution of sources to the entire community. Here we combined stable isotope analysis with standardized measurements of abundance and biomass of fishes and invertebrates in seven waterholes of a wet–dry tropical river sampled early and late in the dry season. We showed that periphyton (as opposed to phytoplankton and terrestrial C3 plant detritus) was responsible for most standing fish biomass (range 42%–97%), whereas benthic invertebrates were reliant on a mixture of the three sources (range 26%–100%). Furthermore, larger, older fishes at high trophic levels (catfish Neoarius spp., sleepy cod Oxyeleotris lineaolatus and barramundi Lates calcarifer) were supported almost exclusively by periphyton. Phytoplankton and detritus supported a considerable biomass of benthic and pelagic invertebrates, but only in taxa that occupied low trophic levels (e.g. snails). These measurements provide further evidence that although periphyton is relatively inconspicuous relative to other sources, it contributes disproportionately to metazoan biomass in wet–dry tropical rivers. Copyright © 2012 John Wiley & Sons, Ltd.     

Bone cement or bone substitute augmentation of pedicle screws improves pullout strength in posterior spinal fixation

Pedicle screws are widely used to fix posterior spinal implants. However, in some situations, such as at the ends of long constructs in scoliosis correction, the screws may pull out of the pedicles. This limits the use of pedicle screw fixation where bone quality is poor. The aim of this study was to investigate the effect of using either a low-viscosity bone cement (Palacos LV) or a bone augmentation material (Cortoss) on the pullout strength of typical pedicle screws (5 mm USS Schanz screws). Ten lumbar calf vertebrae were implanted with pedicle screws. One screw was inserted as normal, and the contralateral screw was augmented with Palacos LV or Cortoss. A plate was then cemented to the posterior surface of each pedicle and the screws were pulled out using a tensile testing machine. The pullout strength of the non-augmented screws was 1203±260 N, while the pullout strength of the augmented screws was 1970±220 N (Palacos LV) and 2021±342 N (Cortoss). Both Palacos LV and Cortoss significantly increased the pullout strength (p=0.0213 and p=0.0029, respectively). There was no significant difference between the Palacos LV and Cortoss groups (p=0.79).     

Voltammetric measurement in supercritical CO2 utilizing a water-in-CO2 microemulsion

A novel method for voltammetric measurement in supercritical CO2 is described. In this method a water-in-supercritical CO2 microemulsion is utilized to raise the conductivity of the fluid phase. Well-defined voltammograms for the redox reactions of ferrocene and tetramethyl-p-phenylenediamine were obtained in supercritical CO2 in the presence of the microemulsion. The electrolysis product is stabilized in the water core of the microemulsion. This implies a wide range of electrochemical synthesis involving ionic or radical species in supercritical CO2 may be possible utilizing the microemulsion. The electrochemical results obtained from the water-in-supercritical CO2 microemulsion system are different from that obtained from a supercritical CO2-ethanol mixture system.     

Superresolution of binary images with a nonlinear interpolative neural network

Superresolution is the process by which the bandwidth of a diffraction-limited spectrum is extended beyond the optical passband. Many algorithms exist that are capable of superresolution; however, most are iterative methods, which are ill suited for real-time operation. One approach that has been virtually ignored is the neural-network approach. We consider the feedforward architecture known as a multilayer perceptron and present results on simulated binary images blurred by a diffraction-limited, circular-aperture optical transfer function and sampled at the Nyquist rate. To avoid aliasing, the network performs as a nonlinear spatial interpolator while simultaneously extrapolating in the frequency domain.