ABSTRACT
Nanowires and nanotubes were synthesized from metals and metal oxides using templated cathodic electrodeposition. With templated electrodeposition, small structures are electrodeposited using a template that is the inverse of the final desired shape. Dielectrophoresis was used for the alignment of the as-formed nanowires and nanotubes between prepatterned electrodes. For reproducible nanowire alignment, a universal set of dielectrophoresis parameters to align any arbitrary nanowire material was determined. The parameters include peak-to-peak potential and frequency, thickness of the silicon oxide layer, grounding of the silicon substrate, and nature of the solvent medium used. It involves applying a field with a frequency >10(5) Hz, an insulating silicon oxide layer with a thickness of 2.5 µm or more, grounding of the underlying silicon substrate, and the use of a solvent medium with a low dielectric constant. In our experiments, we obtained good results by using a peak-to-peak potential of 2.1 V at a frequency of 1.2 × 10(5) Hz. Furthermore, an indirect alignment technique is proposed that prevents short circuiting of nanowires after contacting both electrodes. After alignment, a considerably lower resistivity was found for ZnO nanowires made by templated electrodeposition (2.2-3.4 × 10(-3) Ωm) compared to ZnO nanorods synthesized by electrodeposition (10 Ωm) or molecular beam epitaxy (MBE) (500 Ωm).
Subject(s)
Electroplating/methods , Nanotubes/chemistry , Nanowires/chemistry , Materials Testing , Metals/chemistry , Microelectrodes , Nanotechnology/methods , Silicon/chemistry , Surface PropertiesABSTRACT
Cell culture tests, DNA colony blot hybridization and polymerase chain reaction were used to examine classical enteropathogenic Escherichia coli (EPEC) for the presence of Shiga-like toxin (SLT). Fifteen of 155 strains from West Germany, originally identified as EPEC on the basis of serotyping, were shown to harbor either SLT-I or SLT-II genes. All strains that hybridized with the 20-base oligonucleotide probes which are complementary to slt-IA or slt-IIA sequences derived from the genomic DNA of enterohemorrhagic E. coli O157:H7 strain 933 produced moderate or high levels of cytotoxin in Vero and HeLa cell assays. Four additional strains of low to moderate cytotoxicity did not hybridize with either probe. Five different serogroups producing SLTs were identified: O26, O55, O111, O119 and O128. All three SLT-positive E. coli O26:H11 and four of five E. coli O111:H- isolates hybridized with a 3.4 kilobase fragment (CVD 419 probe) derived from the 60-megadalton plasmid of EHEC O157:H7. Seven of the 15 SLT-gene positive strains were associated with bloody diarrhea, six isolates were from patients with hemolytic uremic syndrome (HUS). Based on their clinical, epidemiological, pathogenic and genetic features SLT-producing E. coli among classical EPEC mimic enterohemorrhagic E. coli O157:H7 and might be considered as EHEC.
Subject(s)
Bacterial Toxins/biosynthesis , Diarrhea, Infantile/microbiology , Diarrhea/microbiology , Escherichia coli Infections/microbiology , Escherichia coli/genetics , Adult , Animals , Bacterial Toxins/genetics , Child , Chlorocebus aethiops , Cytotoxins/biosynthesis , Cytotoxins/genetics , Enterotoxins/biosynthesis , Enterotoxins/genetics , Escherichia coli/classification , Escherichia coli/metabolism , HeLa Cells , Hemolytic-Uremic Syndrome/microbiology , Humans , Infant , Nucleic Acid Hybridization , Oligonucleotide Probes , Polymerase Chain Reaction , Serotyping , Shiga Toxin 1 , Shiga Toxin 2 , Vero CellsABSTRACT
Bath immunization of carp (Cyprinus carpio L) resulted in protection of fish at natural challenge. Stimulation of leukocytes derived from thymus, spleen, anterior kidney and mid-kidney of fish immunized with Flexibacter columnaris bacterin revealed the presence of antigen sensitized cells in all lymphoid tissues except the anterior kidney. After 28 days a response was obtained in thymus and spleen leukocyte cultures.
Subject(s)
Fish Diseases/immunology , Immunization/veterinary , Leukocytes/immunology , Myxococcales/immunology , Animals , Antigens, Bacterial/immunology , Bacterial Infections/immunology , Bacterial Infections/veterinary , Bacterial Vaccines/administration & dosage , Carps , Female , Immunization/methods , Kidney/cytology , Lymphocyte Activation , Male , Mitogens/pharmacology , Spleen/cytology , Thymus Gland/cytologyABSTRACT
The optimization of a leukocyte stimulation microassay with carp (Cyprinus carpio L.) leukocytes is described. Leukocytes were isolated from the thymus, anterior kidney, spleen, mid-kidney and peripheral blood. Leukocyte cultures were stimulated with PHA-P, LPS (Escherichia coli 055: B5) PWM, ConA and PPD from Mycobacterium fortuitum. The optimum incubation temperature for leukocyte cultures differed 3.5 days for leukocyte cultures derived from lymphoid organs and 4.5 days for peripheral blood lymphocyte cultures. Leukocytes from various organ sources showed similar reactivity patterns to stimulation in vitro by different mitogens. The results of these mitogen stimulations did not present sufficient arguments in favour of compartmentation.
Subject(s)
Carps/immunology , Cyprinidae/immunology , Lymphocyte Activation , Lymphocytes/immunology , Animals , Carps/blood , Cells, Cultured , Concanavalin A/pharmacology , Escherichia coli/immunology , Kidney/immunology , Kinetics , Mitogens , Phytohemagglutinins/pharmacology , Spleen/immunology , Thymus Gland/immunologyABSTRACT
A technique is described for exposure and injection of the jugular vein in the red-eared turtle. Satisfactory anaesthesia and muscular relaxation for this procedure was obtained by intramuscular injection of a mixture of chloral hydrate and sodium pentobarbital at a dose of 2.5 ml/kg bodyweight. Induction time was 30-45 minutes. Time for surgical procedure 30-45 minutes. Recovery time 1-8 hours.
