漳州市花卉业发展的思路与对策

1995年,省、市领导决定在漳州建立"闽南花卉中心",项目区规划从龙海九湖至漳浦长桥沿324国道建成一条长50公里,两侧各延伸300米、总面积666公顷的百里花卉长廊.花卉中心进行了高科技、集约化生产和经营,已成为全省花卉品种最齐全、规模最大的花卉生产基地和花卉市场.多年来由于种种因素限制,形成"三缺一"的局面.本文针对漳州市花卉业发展的现状与问题,提出"十五"期间发展思路与对策.     

Atmosphere of Mars: Mariner IV Models Compared

Three classes of models for the atmosphere of Mars differ in identifying the main ionospheric layer measured by Mariner IV as being analogous to a terrestrial F(2), F(1), or E layer. At an altitude of several hundred kilometers, the relative atmospheric mass densities for these models (in the order named) are approximately 1, 10(2), and 10(4), and the temperatures are roughly 100 degrees , 200 degrees , and 400 degrees K. Theory and observation are in best agreement for an F, s model, for which photodissociation of CO(2), and diffusive separation result in an atomic-oxygen upper atmosphere, with O(+) being the principal ion in the isothermal topside of the ionosphere. The mesopause temperature minimum would be at or below the freezing point of CO(2), and dry ice particles would be expected to form. However, an F(1) model, with molecular ions in a mixed and warmer upper atmosphere, might result if photodissociation and diffusive separation are markedly less than would be expected from analogy with Earth's upper atmosphere. The E model proposed by Chamberlain and McElroy appears very unlikely; it is not compatible with the measured ionization profile unless rather unlikely assumptions are made about the values, and changes with height, of the effective recombination coefficient and the average ion mass. Moreover our theoretical heat-budget computations for the atmospheric region probed by Mariner IV indicate markedly lower temperatures and temperature gradients than were obtained for the E model.     

Bioactivity of benthic and picoplanktonic estuarine cyanobacteria on growth of photoautotrophs: inhibition versus stimulation

Understanding potential biochemical interactions and effects among cyanobacteria and other organisms is one of the main keys to a better knowledge of microbial population structuring and dynamics. In this study, the effects of cyanobacteria from benthos and plankton of estuaries on other cyanobacteria and green algae growth were evaluated. To understand how the estuarine cyanobacteria might influence the dynamics of phytoplankton, experiments were carried out with the freshwater species Microcystis aeruginosa and Chlorella sp., and the marine Synechocystis salina and Nannochloropsis sp. exposed to aqueous and organic (70% methanol) crude extracts of cyanobacteria for 96 h. The most pronounced effect observed was the growth stimulation. Growth inhibition was also observed for S. salina and M. aeruginosa target-species at the highest and lowest concentrations of cyanobacterial extracts. The methanolic crude extract of Phormidium cf. chalybeum LEGE06078 was effective against S. salina growth in a concentration-dependent manner after 96 h-exposure. All of the cyanobacterial isolates showed some bioactivity on the target-species growth, i.e., inhibitory or stimulating effects. These results indicate that the analyzed cyanobacterial isolates can potentially contribute to blooms' proliferation of other cyanobacteria and to the abnormal growth of green algae disturbing the dynamic of estuarine phytoplankton communities. Since estuaries are transitional ecosystems, the benthic and picoplanktonic estuarine cyanobacteria can change both freshwater and marine phytoplankton succession, competition and bloom formation. Furthermore, a potential biotechnological application of these isolates as a tool to control cyanobacteria and microalgae proliferation can be feasible. This work is the first on the subject of growth responses of photoautotrophs to cyanobacteria from Atlantic estuarine environments.     

Mixed poly (ethylene glycol) and oligo (ethylene glycol) layers on gold as nonfouling surfaces created by backfilling

Backfilling a self-assembled monolayer (SAM) of long poly (ethylene glycol) (PEG) with short PEG is a well-known strategy to improve its potential to resist fouling. Here it is shown, using x-ray photoelectron spectroscopy, contact angle, and atomic force microscopy, that backfilling PEG thiol with oligo (ethylene glycol) (OEG) terminated alkane thiol molecules results in underbrush formation. The authors also confirm the absence of phase separated arrangement, which is commonly observed with backfilling experiments involving SAMs of short chain alkane thiol with long chain alkane thiol. Furthermore, it was found that OEG addition caused less PEG desorption when compared to alkane thiol. The ability of surface to resist fouling was tested through serum adsorption and bacterial adhesion studies. The authors demonstrate that the mixed monolayer with PEG and OEG is better than PEG at resisting protein adsorption and bacterial adhesion, and conclude that backfilling PEG with OEG resulting in the underbrush formation enhances the ability of PEG to resist fouling.     

Shiga toxin genes in avian Escherichia coli

The purpose of this study was to determine the presence of stx genes in avian pathogenic Escherichia coli (APEC). We examined 97 APEC isolates: 34 from lesions of avian cellulitis, 31 from avian septicemia, 13 from swollen head syndrome (SHS) in chickens, and 19 from diseased turkeys. We also examined five isolates from the feces of healthy chickens. All 102 E. coli isolates were tested for the presence of stx genes by PCR amplification and by colony blots using probes specific for stx1 and stx2. Fifty-three percent (52) of the 97 APEC carried stx gene sequences: one isolate carried stx2 sequences, two carried both stx1 and stx2 sequences, and the remaining 49 isolates carried only stx1 sequences. Twenty-six isolates were positive by both hybridization and PCR amplification, 10 were positive by PCR only, and 16 were positive by hybridization only. All the stx-positive isolates were negative by PCR for the eae and E-hlyA genes. The five isolates from healthy chickens were all negative for stx. All 13 SHS isolates were positive for the stx1 gene and had low titres for cytotoxicity in the Vero cell assay (VCA). Other stx-positive isolates were negative in the VCA. The stx1 gene from one SHS E. coli isolate was cloned and sequenced and shown to be identical to that of the stx gene of Shigella dysenteriae. The observations indicate that stx1 gene sequences are widespread among APEC but that cytotoxicity on Vero cells is uncommon.     

Suspected clindamycin-associated oesophageal injury in cats: five cases

The clinical findings, treatment and outcome of suspected clindamycin-associated oesophageal injury in five cats are reported. All cats were treated with one 75 mg clindamycin capsule twice daily (dose range 12-19 mg/kg). Capsules were administered without food or a water bolus. Dysphagia, regurgitation, choking or gagging were seen 3-9 days after starting clindamycin. On oesophagoscopy, three cats had oesophagitis, one of which progressed to stricture formation. Two cats had an oesophageal stricture at first presentation. This is the first report of suspected clindamycin-associated oesophageal injury in cats. It serves to further alert practitioners to the potential for drug-induced oesophageal disorders (DIOD) in cats treated with oral medications and to urge prevention by promoting a change in dosing practices.     

Antemortem diagnosis and treatment of toxoplasmosis in two cats on cyclosporin therapy

Clinical toxoplasmosis was diagnosed antemortem in two cats being treated with therapeutic doses of cyclosporin. The diagnosis was made by detecting tachyzoites on cytological examination of bronchoalveolar lavage fluid from one case and pleural effusion from the other. Despite early diagnosis and aggressive treatment in both cases, only one cat survived. Reactivation of latent Toxoplasma gondii infection secondary to cyclosporin-induced immunosuppression was considered likely in both cases. The presence of respiratory signs in cats treated with cyclosporin should alert clinicians to the possibility of clinical toxoplasmosis. Consideration should be given to determining the serostatus of cats to T gondii prior to use of drugs which are potent inhibitors of cell mediated immunity, such as cyclosporin. Two cases of feline toxoplasmosis are presented.