Development of an ultraprecision metal mirror on additively manufactured Ti-6Al-4V.

Metal mirrors for precise optical applications are commonly fabricated by coating of a metal base substrate with a nickel-phosphorus alloy (NiP). The NiP layer is then processed by precision diamond turning and polishing to obtain a high-quality mirror surface. In this work, Ti-6Al-4V samples that were made by additive manufacturing, also called 3D printing, were used as a base for the development of metal mirrors. The additively manufactured samples were electroplated with a NiP coating and machined using single-point diamond turning (SPDT) to obtain a flat mirror with optical quality and low form error surface. The periodic structure of the SPDT toolmark was then removed by polishing postprocessing. Polishing optimization was first performed on NiP-coated aluminum test samples to find an optimal polishing setup. Based on this optimization, postprocessing of titanium samples was carried out by pitch polishing in combination with 1, 0.25, and 0.1µm diamond slurries. Using this polishing processing, a scratch-free surface was attained with surface microroughness below 0.5 nm.

Facile synthesis and rheological characterization of nanocomposite hyaluronan-organoclay hydrogels.

We report a facile methodology for the synthesis of inorganic-organic hydrogels based on integrative assembly of aminopropyl magnesium phyllosilicate (aminoclay) and sodium salt of hyaluronic acid. The viscoelastic materials produced by electrostatic interactions and crosslinking of hyaluronan in the presence of exfoliated synthetic organoclay results in the formation of gel-like behavior retaining a high amount of water. This was confirmed by a rheological study revealing significant dominance of the elastic response over the entire deformation frequency range used. The mechanical strength of the aminoclay-hyaluronan hydrogels was found to be higher than that for related materials based on poly(vinylpyrrolidone)-aminoclay hydrogels.

Determination of 5-fluorouracil and 5-fluoro-2'-deoxyuridine-5'-monophosphate in pancreatic cancer cell line and other biological materials using capillary electrophoresis.

Capillary zone electrophoresis (CZE) was used for the rapid determination of 5-fluorouracil (5-FU) and 5-fluoro-2'-deoxyuridine-5'-monophosphate (FdUMP) in pancreatic cancer cell line (PANC-1), culture medium, plasma and pancreatic tissue. The assay is based upon protein precipitation with acetonitrile followed by a 9-min CZE analysis of the supernatant in an uncoated fused-silica capillary employing a borate buffer and on-column absorbance detection at 265 nm. Using 50 microl of sample, 5-FU levels between 4.12 and 132 microg/ml (31.7-1000 microM) were found to provide linear calibration graphs. Intra-day and inter-day RSD values evaluated from peak height ratios (n=5) were <7.6 and <8.8%, respectively. Corresponding RSD values of detection times (n=7) were <1 and <1.5%, respectively. The limits of detection for 5-FU and FdUMP were 1.72 and 5.29 microg/ml, respectively. As application, the accumulation of 5-FU by PANC-1 cells over a 4-h time period was investigated. Having a culture medium concentration of 100 microg/ml, the 5-FU cell content was estimated to become equal to that of the surrounding medium (i.e., 100 microg/ml or 3.61 fmol per cell with a volume of 4.7 pl) within that time period. The sensitivity of the assay was sufficient for the determination of 5-FU in all cell samples. FdUMP, however, could not be detected in these samples. Furthermore, the data obtained in uncoated capillaries are compared to those measured in a fused-silica capillary whose inner surface was coated with linear polyacrylamide (about 10-fold reduction of electroosmosis). The latter capillary format was found to be useless for simultaneous analysis of 5-FU and FdUMP in pancreatic cells but could be potentially useful for analysis of these compounds in plasma.

Therapeutic drug monitoring of albendazole: determination of albendazole, albendazole sulfoxide, and albendazole sulfone in human plasma using nonaqueous capillary electrophoresis.

A nonaqueous capillary electrophoretic method (NACE) for the fast determination of plasma levels of albendazole (ABZ), albendazole sulfoxide (ABZSO), and albendazole sulfone (ABZSO2) is described. The assay is based upon liquid/liquid extraction of these compounds using dichloromethane at pH 10.2 (recovery between 63 and 98%), followed by a NACE separation performed within 8 min employing a 0.036 M borate buffer (apparent pH 9.9) in a mixture of methanol and N-methylformamide (1:3) and on-column absorbance detection at 280 nm. Using 0.5 mL of plasma and extract reconstitution in 200 microL N-methylformamide, drug levels between 1.0-10 microM were found to provide linear calibration graphs. Intraday and interday imprecisions evaluated from peak area ratios (n = 5) were <10% and <12%, respectively. Corresponding imprecisions of detection times (n = 5) were <1% and <6%, respectively. The limit of detection (LOD) for ABZ, ABZSO and ABZSO2 was 8 x 10(-7) M. The reliability of the method developed was verified via analysis of 45 plasma samples obtained from patients treated with ABZ. Good agreement was obtained between the levels of ABZSO and those determined by routine HPLC. ABZ was found to be undetectable in all patient samples, whereas the levels of ABZSO2 were below or close to LOD.

Analysis of orotic acid in human urine by on-line combination of capillary isotachophoresis and zone electrophoresis.

The techniques of the on-line combination of capillary isotachophoresis with zone electrophoresis in two coupled capillaries (ITP-CZE) and a single capillary zone electrophoresis (CZE) were used for the sensitive determination of orotic acid (OA) in human urine. The simple CZE system was successfully applied for fast and reliable analyses of urine of healthy adult volunteers (the detection limit 1.7.10(-6) M OA, the total time of analysis 6 min). However, this method failed in analyses of OA in urine of ill children due to more complex matrix of the samples. Here, the ITP preconcentration and preseparation step coupled on-line with CZE proved to serve well with an electrolyte system developed and optimized for this purpose. The maximum selectivity and resolution of OA from other sample constituents in ITP-CZE was achieved by use of an electrolyte system of very low pH 2.15 both for ITP and CZE stage. The sensitivity of detection and simplicity of OA identification were enhanced by use of an external UV scanning detector. High sensitivity of ITP-CZE combination (limit of detection 3.10(-7) M OA), low sample consumption (1 microliter), good reproducibility of migration times (inter-day RSD < 1.86%) and acceptable reproducibility of the determination of OA in urine samples (average RSD = 7.27%) make this technique suitable for routine determination of trace concentration of OA especially in urine of ill children under various pathological conditions and medication.

Quantitative trace analysis of L-ascorbic acid in human body fluids by on-line combination of capillary isotachophoresis and zone electrophoresis.

On-line combination of capillary isotachophoresis and zone electrophoresis performed in two coupled capillaries (ITP-CZE) is used for the trace analysis of L-ascorbic acid in human serum, urine and stomach fluid. At the ITP stage, anionic sample components are separated into individual zones and macrocomponents are detected and driven out of the migration path. In the CZE stage, only a small segment of the sample zones containing L-ascorbic acid is analyzed. High sensitivity of this hyphenated method (limit of detection, 0.09-0.15 mg/L), low sample volume consumption (2 microL), and acceptable reproducibility of the results (relative standard deviation, 8%) in the concentration range 0.1-15 mg/L demonstrate that the method is applicable for the study of the relation between the content of L-ascorbic acid in body fluids and the state of health of a person, in which lower amounts of L-ascorbic acid than the normal levels (i.e., 5.1-15.1 mg/L in human serum and 12.5-26.8 mg/L in urine) are expected. Possible interferences of other components of the body fluids are excluded by good correlation of the results obtained by the ITP-CZE method and a routine colorimetric method.

Ceftriaxon in the treatment of severe bacterial infections.

The efficacy of ceftriaxon (Rocephin Roche) therapy has been studied by our team in two groups of patients. The first one consisted of 10 children suffering from a diffuse purulent appendical peritonitis brought about by a mixed aerobe and anaerobe microbial flora, the second one comprising 7 patients with severe infections caused by problematic aerobe pathogens. The clinical effect of the treatment was good in 16 out of the 17 cases, in one patient it could not be evaluated. Even though a high degree of sensitivity to Rocephin could be demonstrated bacteriologically by the disc method in all the aerobe germs present, the results of titration of the bactericide capacity of the sera during treatment indicate the need for laboratory monitoring of the course of therapy of severe infections due to pseudomonas aeruginosa. Parenteral administration of Rocephin was well tolerated and the laboratory alterations seemin the course of therapy of severe infections due to Pseudomonas aeruginosa. Parenteral administration of Recephin was well tolerated and the laboratory alterations seen in the postoperative ileus due to strangulation and adhesions--cannot be recommended.

Antimicrobial profile of ceftazidime: the situation in three larger hospitals in Prague between 1981 and 1983.

As a part of preclinical trials of 2,996 clinical isolates from three larger hospitals in Prague were qualitatively and quantitatively assayed for in vitro sensitivity to ceftazidime. In gramnegative bacteria the incidence of resistance to ceftazidime in strain of Enterobacter, Serratia Proteus and Pseudomonas species ranged from 4% to 6% of strains. In grampositive bacteria only strains of enterococci, listeriae and anaerobic bacteria are excluded from the action of this broad-spectrum antibiotic. According to present experiences the antipseudomonal activity of ceftazidime is approximately the same as that of cefsulodine and cefoperazone. Alarmingly, one of the Pseudomonas aeruginosa isolates was found to show a distinct multiresistance to all available lactam, aminoglycoside and broad-spectrum antimicrobials, including ceftazidime.