The isolation and extraction of natively occurring signaling peptides (SPs) from tissue is a critical first step in characterizing these peptides. Recent studies have outlined several approaches designed to preserve and extract SPs from tissue. Here, we demonstrate a surprisingly simple method to extract SPs from tissue samples, ranging from cell clusters to brain punches to intact brain regions, using a matrix often employed in matrix-assisted laser desorption/ionization mass spectrometry-2,5-dihydroxybenzoic acid (DHB). DHB allows for the effective extraction of endogenous peptides from tissue as well as long-term preservation of tissue samples and extracts. Using the mouse pituitary gland as a model, the extraction protocol effectively recovers 24 known and many additional putative peptides from individual samples. Peptide extracts stored in the DHB extraction media are stable for years without freezing. The approach is also effective for other neuronal tissues; the complement of neuropeptides in bag cell neuron clusters from the Aplysia central nervous system, the rat cerebellum, and rat dorsal striatum also have been examined. Advantages of this new extraction procedure are its technical simplicity, reproducibility, ease of remote preparation of samples, and long-term sample preservation without freezing. 相似文献
This work is dealing with the influence of surface treatment on ohmic contacts to hexagonal N-type SiC with medium doping level. The contact materials were Ni and Ni2Si. The structures had to be annealed at high temperatures in order to reach ohmic behavior. A number of surface treatment methods were tested: wet cleaning, plasma etching, intentional oxidation with etching, H2 annealing and their combinations. After some types of cleaning, the SiC surface was immediately analysed using the XPS method. The results of the analyses showed that the composition of the surface was not much influenced by these treatments. At lower annealing temperatures (approx. up to 850 °C) the prepared contacts showed Schottky behavior with large scatter of parameters. After annealing at approx. 960 °C, where the onset of ohmic behavior is expected, the structures were truly ohmic and of good parameters. Cleaning methods had just a negligible influence on the electrical parameters of the ohmic contacts. An explanation for these observed facts is suggested: Although - already on the basis of the XPS results - we could speak about a negligible influence of the cleaning onto the contact parameters, there might come across also other mechanisms coming from interaction of contact materials with SiC, which caused similar behavior of ohmic contacts on differently treated surfaces. 相似文献
A new copolymer of N-[(tert-butylperoxy)methyl]acrylamide (tBPMAAm), containing a primary–tertiary peroxide group and maleic anhydride (MA), was synthesized and employed as a reactive surfactant (inisurf) for the emulsion polymerization of styrene to yield surface-functionalized (peroxidized) reactive latex particles. The copolymerization characteristics were analyzed to determine the monomer reactivity ratios and to provide a way to control the copolymer composition. The ability of tBPMAAm–MA to act as a reactive surfactant during emulsion polymerization was confirmed by the synthesis of monodisperse polystyrene latexes of varying particle size. In addition, peroxide groups were localized on the surface of the particles in a controllable amount (depending on the copolymer concentration), thus, providing the opportunity for further modification of the surface of the particles. This novel copolymer is expected to be a promising and efficient material in the synthesis of functional polymer nanoparticles with well-defined core–shell morphologies. 相似文献
The corrosion behavior of pure and lanthanum doped, sol – gel‐derived, mullite ceramics in nitric acid aqueous solutions with various concentrations was investigated and compared. Samples sintered at a temperature of 1600°C for 4 h were characterized using powder X‐ray diffraction, SEM, and energy dispersive X‐ray spectroscopy. The corrosion behavior was explored by measuring the amount of eluted ions using atomic absorption spectrophotometry and inductively coupled plasma optical emission spectrometry (ICP‐OES). The doped sample was found to be more susceptible to dissolution in the corrodent, having higher leaching rates. The amounts of eluted lanthanum ions were in order of magnitude higher than amounts of silicon and aluminum. Those phenomena were attributed to the incorporation of lanthanum in the glassy phase, forming SiO2 – La2O3‐rich glassy phase, which can dissolve in corrodent more easily than SiO2‐rich glassy phase in the pure sample. 相似文献
As a source of the high purity hydrogen, sodium and potassium borohydrides are investigated in terms of long-term stability in the form of the concentrated solutions, heterogeneous mixtures and in the solid state corresponding to NaBH4 or KBH4 crystal hydrates. In order to improve their stability during the long-term storage sodium and potassium hydroxides were added to the initial borohydride compositions. The effect of temperature, concentration of the borohydride and the alkaline solution, and the nature of the cation in the alkaline solution on the rate of borohydride hydrolysis was investigated. The differential technique developed for evaluation of the rate of borohydride hydrolysis was successfully applied for the determination of the long-term stability of the water-alkaline solutions containing NaBH4(KBH4)·5H2O with 1–10 wt.% of NaOH or KOH at 30 °C and 50 °C. 相似文献
Metallurgical coke is made from a mix of several types of coal that contain various minerals, including quartz, carbonates, feldspars, sulphides and a number of phyllosilicates, represented by clay minerals and micas. During coking and coke consumption processes the minerals undergo various physical and chemical changes, which in the case of coke oven batteries include desulphurization, decarbonation, dehydration, dehydroxylation, polymorph transformations, melting with the formation of an alkali and silica‐rich liquid, and transformation to another crystalline phase. The typical modifications of mineral phases in a blast furnace (BF) coke are polymorph transformations, melting, and the formation of another crystalline phase. These events are also preceded by notable changes in the shape of crystalline aggregates. All these changes affect the coke properties and the processes occurring in a BF. Mineralogical data can help us to better understand the processes taking place in coke batteries and in a BF, and to improve the quality of a coke by more careful selection of coal blends and setting optimal temperatures for its pre‐heating. The degradation of a BF coke by alkalis can be reduced by the addition of certain minerals to the feed coke before charging into the BF. 相似文献
A new method, duplex positioning method DPM, to increase the fatigue lifetime of the threaded connection under eccentric loading is presented. When DPM is applied, the most damaged stud regions periodically are removed from risky positions by a change of the stud’s and nut’s mutual position in the axial direction alongside with a change of the stud’s position in respect to bending plane. The mathematical model for DPM enables us to predict its efficiency. To simulate the fatigue strength of the stud the following was used: Patterson’s and Kenny’s thread deflection factors, solutions for the distributions of the axial load and bending moment along the threads, Neuber’s method for the stress concentration factors in multiplier notches, Heywood’s formulas for the stress due to the thread flank loading and for the combined stresses, as well as the results of the photoelastic analysis of the araldite models under eccentric loading.