无定形锰氧化物在氮素损失中的作用

Studies have been made,by ^15N-tracer technique on nitrogen loss resulting from adding amorphous manganese oxide to NH4^ -N medium under anaerobic conditions.The fact that the total nitrogen recovery was decreased and that ^15NO2,^15N2O,^15N^14NO,^15NO,^15N2 and ^15N^14N were emitted has proved that,like amorphous iron oxide,amorphous manganese oxide can also act as an electron acceptor in the oxidation of NH4^ -N under anaerobic conditions and give rise to nitrogen loss.This once again illustrates another mechanism by which the loss of ammonium nitrogen in paddy soils is brought about by amorphous iron and manganese oxides.The quantity of nitrogen loss by amorphous manganese oxide increased with an increase in the amount of amorphous manganese oxide added and lessened with time of its aging.The nitrogen loss resulting from amorphous manganese oxide was less than that from amorphous iron oxide.And the nitrogen loss resulting from amorphous manganese oxide was less than that from amorphous iron oxide.And the nitrogen loss by cooperation of amorphous manganese oxide and microorganisms (soil suspension) was larger than that by amorphous manganese oxide alone.In the system,nitrogen loss was associated with the specific surface ares and oxidation-reduction of amorphous manganese oxide.However,their quantitative relationship and the exact reaction processes of nitrogen loss induced by amorphous manganese oxide remain to be further studied.     

Competitive degradation and detoxification of carbamate insecticides by membrane anodic Fenton treatment

The competitive degradation of six carbamate insecticides by membrane anodic Fenton treatment (AFT), a new Fenton treatment technology, was carried out in this study. The carbamates studied were dioxacarb, carbaryl, fenobucarb, promecarb, bendiocarb, and carbofuran. The results indicate that AFT can effectively degrade these insecticides in both single component and multicomponent systems. The carbamates compete for hydroxyl radicals, and their kinetics obey the previously developed AFT kinetic model quite well. Hydroxyl radical reaction rate constants were obtained, and they decrease in the following order: dioxacarb approximately carbaryl > fenobucarb > promecarb > bendiocarb > carbofuran. The AFT is shown to have higher treatment efficiency at higher temperature. Degradation products of the carbamates were determined by gas chromatography/mass spectrometry, and it appears that degradation can be initiated by hydroxyl radical attack at different sites in the molecule, depending on the individual structure of the compound. Substituted phenols are the commonly seen degradation products. The AFT treatment can efficiently remove the chemical oxygen demand of the carbamate mixture, significantly increasing the biodegradability. Earthworm studies show that the AFT is also an effective detoxification process.     

Acidic mammalian chitinase in asthmatic Th2 inflammation and IL-13 pathway activation

Chitin is a surface component of parasites and insects, and chitinases are induced in lower life forms during infections with these agents. Although chitin itself does not exist in humans, chitinases are present in the human genome. We show here that acidic mammalian chitinase (AMCase) is induced via a T helper-2 (Th2)-specific, interleukin-13 (IL-13)-mediated pathway in epithelial cells and macrophages in an aeroallergen asthma model and expressed in exaggerated quantities in human asthma. AMCase neutralization ameliorated Th2 inflammation and airway hyperresponsiveness, in part by inhibiting IL-13 pathway activation and chemokine induction. AMCase may thus be an important mediator of IL-13-induced responses in Th2-dominated disorders such as asthma.     

Mutations in a human ROBO gene disrupt hindbrain axon pathway crossing and morphogenesis

The mechanisms controlling axon guidance are of fundamental importance in understanding brain development. Growing corticospinal and somatosensory axons cross the midline in the medulla to reach their targets and thus form the basis of contralateral motor control and sensory input. The motor and sensory projections appeared uncrossed in patients with horizontal gaze palsy with progressive scoliosis (HGPPS). In patients affected with HGPPS, we identified mutations in the ROBO3 gene, which shares homology with roundabout genes important in axon guidance in developing Drosophila, zebrafish, and mouse. Like its murine homolog Rig1/Robo3, but unlike other Robo proteins, ROBO3 is required for hindbrain axon midline crossing.     

Germline allele-specific expression of TGFBR1 confers an increased risk of colorectal cancer

Much of the genetic predisposition to colorectal cancer (CRC) in humans is unexplained. Studying a Caucasian-dominated population in the United States, we showed that germline allele-specific expression (ASE) of the gene encoding transforming growth factor-beta (TGF-beta) type I receptor, TGFBR1, is a quantitative trait that occurs in 10 to 20% of CRC patients and 1 to 3% of controls. ASE results in reduced expression of the gene, is dominantly inherited, segregates in families, and occurs in sporadic CRC cases. Although subtle, the reduction in constitutive TGFBR1 expression alters SMAD-mediated TGF-beta signaling. Two major TGFBR1 haplotypes are predominant among ASE cases, which suggests ancestral mutations, but causative germline changes have not been identified. Conservative estimates suggest that ASE confers a substantially increased risk of CRC (odds ratio, 8.7; 95% confidence interval, 2.6 to 29.1), but these estimates require confirmation and will probably show ethnic differences.     

播种期对各生育时期甜高粱叶片性状的影响

对甜高粱品种辽饲杂3号在4个播种期条件下进行了叶片性状指标测定试验,分析了不同播种期甜高粱在拔节、孕穗、开花、灌浆期叶绿素含量、比叶重、叶面积指数及成熟期绿叶数等叶部性状变化规律.结果表明,叶片叶绿素含量在孕穗期与开花期达最大值,早播时甜高粱前期叶绿素含量高,晚播时后期叶绿素含量较高.比叶重在灌浆期达最大值,且以晚播甜高粱的比叶重较大.叶面积指数随播种期延迟,并有下降趋势,但晚播甜高粱在成熟期时叶面积指数较高.绿叶数的变化趋势类似于叶面积指数.     

Fluorous mixture synthesis: a fluorous-tagging strategy for the synthesis and separation of mixtures of organic compounds

The solution-phase synthesis of organic compounds as mixtures rather than in individual pure form offers efficiency advantages that are negated by the difficulty in separating and identifying the components of the final mixture. Here, a strategy for mixture synthesis that addresses these separation and identification problems is presented. A series of organic substrates was tagged with a series of fluorous tags of increasing fluorine content. The compounds were then mixed, and multistep reactions were conducted to make enantiomers or analogs of the natural product mappicine. The resulting tagged products were then demixed by fluorous chromatography (eluting in order of increasing fluorine content) to provide the individual pure components of the mixture, which were detagged to release the final products.     

Compressibility of M3C60 Fullerene Superconductors: Relation Between Tc and Lattice Parameter

X-ray diffraction and diamond anvil techniques were used to measure the isothermal compressibility of K(3)C(60) and Rb(3)C(60), the superconducting, binary alkali-metal intercalation compounds of solid buckminsterfullerene. These results, combined with the pressure dependence of the superconducting onset temperature T(c) measured by other groups, establish a universal first-order relation between T(c) and the lattice parameter a over a broad range, between 13.9 and 14.5 angstroms. A small secondorder intercalate-specific effect was observed that appears to rule out the participation of intercalate-fullerene optic modes in the pairing interaction.     

Role of nonimmune IgG bound to PfEMP1 in placental malaria

Infections with Plasmodium falciparum during pregnancy lead to the accumulation of parasitized red blood cells (infected erythrocytes, IEs) in the placenta. IEs of P. falciparum isolates that infect the human placenta were found to bind immunoglobulin G (IgG). A strain of P. falciparum cloned for IgG binding adhered massively to placental syncytiotrophoblasts in a pattern similar to that of natural infections. Adherence was inhibited by IgG-binding proteins, but not by glycosaminoglycans or enzymatic digestion of chondroitin sulfate A or hyaluronic acid. Normal, nonimmune IgG that is bound to a duffy binding-like domain beta of the P. falciparum erythrocyte membrane protein 1 (PfEMP1) might at the IE surface act as a bridge to neonatal Fc receptors of the placenta.