用简化模型实现多波抽运拉曼光纤放大器的优化设计

提出了一种优化设计多波抽运拉曼光纤放大器的方法。在不影响系统性能的前提下采用了合理的简化算法以减少运算时间，能够在给定信号光频宽和抽运个数等参量要求下得到符合增益平坦度性能要求的抽运功率和波长的优化配置结果。     

gl(λ) and differential operators preserving polynomials

We discuss a certain generalization of gl _n (), and show how it is connected to polynomial differential operators that leave the polynomial space invariant.     

Ruggedness testing of gas chromatographic method for residual solvents in pharmaceutical substances

Summary Ruggedness testing is performed on a gas chromatographic method for the quantitative determination of residual solvents in steroids. Eight experimental variables or factors which were expected to influence the quantitative results were selected. These factors were divided into two independent groups, i.e. four factors related to the injection process and four factors related to separation and detection. In order to determine interaction between factors and quadratic effects, a central composite design was selected for the set-up of the experiments. Because in the method an internal standard is used, relative peak area was used as response. A deviation of up to 2.5% per factor for the quantitative results was regarded as acceptable. Other responses studied are related to the system suitability. Observed main, quadratic and interaction effects were translated into rugged intervals of the experimental variables by graphical presentation. It was found that besides main effects significant interaction effects were present, for example between the temperature of the injector and the split-flow. Interaction effects can easily result in the reduction of the rugged intervals by a factor of 2. The calculated rugged intervals were compared with the precision of the instrument or factor settings in order to estimate the ruggedness of the factors. Eventually, the maximum effect of the variation in the instrument settings on the quantitative results regarding the precision of the factor settings was found to be only 2.2%. Overall, the method proved to be rugged for most factors, except for the split-flow of the injector for which the method was only rugged to a limited extent.     

Abtrennung quartärer Ammoniumverbindungen über zerlegbare Ionenpaarextrakte mit nachfolgender Identifizierung

Ion-pairs of quaternary ammonium salts with lipophilic anions may be extracted into an organic layer. By using such anions capable to loose their negative charge by protonization (pH shiftment), the ion-pair separated with the organic solvent will be split by treatment with aqueous acids. Of the substances investigated, 6-phenyl-2,4-dinitrophenol seems the most promising. Surplus volatile acid may be removed in vacuo, leaving the quaternary salt as residue. Identification is accomplished by UV spectra of the aqueos solutions and TLC. Interesting observations in the search for spray reagents were: the probable ion-pair nature of the “Dragendorff” complexes, colour reactions of quaternary pyridinium derivatives with potassium hexacyanoferrat(II), and dark spots given by quaternary salts with mercury(I) nitrate on alumina layers.     

Porous sol gel silica films doped with crystalline NiO nanoparticles for gas sensing applications

A reliable sol gel route to synthesize NiO doped SiO₂ films with different NiO content is here described. The films showed detectable and reversible changes in both optical and electrical properties when exposed to some reducing/oxidizing gaseous species at temperatures in the 250°C–350°C range. A functional characterization protocol has been designed and some of the sensing properties of the materials have been investigated for detecting NO₂, CH₄, CO and H₂. An optical transmittance increase up to 2% has been detected for 1% CO in dry air atmospheres, while relative resistance response (R _R = R _gas/R _air) values up to 4.97 for 850 ppm H₂/air mixtures have been registered for conductometric gas sensing. Films at all NiO molar concentrations in the 10% NiO - 40% range showed an optical response to the target gas, while only 30% and 40% NiO films provided a detectable gas induced resistance change.     

Grunds?tzliche Erw?gungen zur automatischen Auswertung der emissionsspektrochemischen Analyse

Zusammenfassung Ausgehend von den Eigenschaften der photoelektrischen und photographischen Registriertechnik, wird für den photographischen Fall ein Programm zur Auswertung mit einem Digital-Rechenautomaten beschrieben. Die Möglichkeiten und Eigenschaften geeigneter Datenerfassungssysteme werden diskutiert. Mittels eines Spitzenwertspeichers ergibt sich eine Lösung, um vom Photometer aus die Daten automatisch zu erfassen. Kriterien, um mit dem Rechenprogramm Ausreißer zu finden, sind möglich für den Fall der Eichkurve, für Analysenwerte ergibt sich die Forderung nach möglichst mehreren, experimentell voneinander unabhängigen Meßreihen. Erhöhte Auswertegeschwindigkeit (0,5% des alten Verfahrens) und große Flexibilität sind die wesentlichen Vorteile dieses Verfahrens.

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Summary On basis of the characteristics of the photoelectric and photographic registration a digital-computer program for the photographic case is described. The possibilities and properties of useful data retrieval systems are discussed. By means of a peak-value indicator the photometric data are automatically detected. The computer program is able to find outliers only in the calibration curve; for analytical values different, experimentally independent measuring groups are necessary. Increased evaluation speed (0.5% of the elder method) and great flexibility are the main advantages of this method.

     

Dissipative self-assembly,competition and inhibition in a self-reproducing protocell model

The bottom-up synthesis of artificial, life-like systems promises to enable the study of emergent properties distinctive to life. Here, we report protocell systems generated from phase-separated building blocks. Vesicle protocells self-reproduce through a phase-transfer mechanism, catalysing their own formation. Dissipative self-assembly by the protocells is achieved when a hydrolysis step to destroy the surfactant is introduced. Competition between micelle and vesicle based replicators for a common feedstock shows that environmental conditions can control what species predominates: under basic conditions vesicles predominate, but in a neutral medium micelles are selected for via a mechanism which inhibits vesicle formation. Finally, the protocells enable orthogonal reactivity by catalysing in situ formation of an amphiphilic organocatalyst, which after incorporation into the vesicle bilayer enantioselectively forms a secondary product.

The bottom-up synthesis of a self-reproducing protocell model enables the study of emergent properties distinctive to life.     

Chemical Synthesis of Proteins with Non‐Strategically Placed Cysteines Using Selenazolidine and Selective Deselenization

Although native chemical ligation has enabled the synthesis of hundreds of proteins, not all proteins are accessible through typical ligation conditions. The challenging protein, 125‐residue human phosphohistidine phosphatase 1 (PHPT1), has three cysteines near the C‐terminus, which are not strategically placed for ligation. Herein, we report the first sequential native chemical ligation/deselenization reaction. PHPT1 was prepared from three unprotected peptide segments using two ligation reactions at cysteine and alanine junctions. Selenazolidine was utilized as a masked precursor for N‐terminal selenocysteine in the middle segment, and, following ligation, deselenization provided the native alanine residue. This approach was used to synthesize both the wild‐type PHPT1 and an analogue in which the active‐site histidine was substituted with the unnatural and isosteric amino acid β‐thienyl‐l ‐alanine. The activity of both proteins was studied and compared, providing insights into the enzyme active site.