An Electrically Heated Au Electrode for Electrochemical Detection in Microchip System

An electrically heated Au electrode which can be used for microchip electrophoresis has been constructed and evaluated. The Au electrode is heated by direct current (DC) getting across the copper wire enlacing the Au electrode. Control and measurement of the temperature at the surface of the heated Au electrode can be easily achieved. Electrochemical characteristics of the heated electrode are investigated. Separation and determination of dopamine (DA) and catechol (CA) on poly(dimethylsiloxane) (PDMS) microchip are performed to evaluate the feasibility and reliability of this heated electrode detection system.     

Modeling of carbonaceous feedstock pyrolysis in a countercurrent tubular reactor

A mathematical model of carbonaceous feedstock pyrolysis in a countercurrent tubular reactor was proposed. It was shown that the pyrolysis in a tubular reactor in which porous carbonaceous feedstock is heated in a countercurrent flow of a heated gas can be highly efficient.     

Comparison of the efficiencies of on-line and high-pressure closed vessel approaches to microwave heated sample decomposition

Two microwave heated digestion techniques have been tested with a view to the evaluation of the effectiveness of wet decomposition procedures: a high-pressure/temperature focused microwave heated and an on-line microwave heated system. The efficiency of decomposition was studied using a number of biological reference materials as well as urine and sewage plant effluent. Oxidation reagents included mixtures of nitric acid, nitric acid/hydrogen peroxide and peroxodisulphate (Oxisolv). The residual carbon content of the digestate was determined coulometrically. Pressurised decomposition of a TFM-Teflon vessel is the most effective procedure (organic material is totally oxidised with nitric acid in a single-step procedure), whereas urine and sewage plant effluent are incompletely decomposed with on-line microwave heated digestion.     

Carbonyl Compounds Containing Formaldehyde Produced from the Heated Mouthpiece of Tobacco Sticks for Heated Tobacco Products

Diverse harmful compounds can be emitted during the heating of tobacco sticks for heated tobacco products (HTPs). In this study, the generation of harmful compounds from the filter, instead of tobacco in tobacco sticks, was confirmed. The heat of a heated tobacco product device can be transferred to the tobacco stick filter, resulting in the generation of harmful compounds from the heated filter. Since the heating materials (tobacco consumable) of the tobacco sticks evaluated in this study were different depending on the brand, the harmful compounds emitted from the heated tobacco stick filters were examined by focusing on the carbonyl compounds, using three different tobacco stick parts. Acetaldehyde and propionaldehyde exhibited the highest concentrations in HTP aerosols produced by heating the tobacco consumable (conventional case) (63.5 ± 18.4 µg/stick and 1.71 ± 0.123 µg/stick, respectively). The aerosols produced by heating tobacco stick filters had higher formaldehyde and acrolein concentrations (0.945 ± 0.214 µg/stick and 0.519 ± 0.379 µg/stick) than the aerosols generated from heated tobacco consumable (0.641 ± 0.092 µg/stick and 0.220 ± 0.102 µg/stick). As such, formaldehyde and acrolein were produced by heating small parts of the mouthpiece of a tobacco stick, regardless of the heated tobacco product brand. In addition, acetone was only detected in the aerosols generated from heated filters (0.580 ± 0.305 µg/stick). Thus, safety evaluations of heated tobacco products should include considerations of the harmful compounds generated by heating tobacco stick mouthpieces for heated tobacco products in addition to those found in heated tobacco product aerosols.     

Solid-state thermal polymerization of 2,4-hexadiyne-1,6-diol

The solid-state thermal polymerization of 2,4-hexadiyne-1, 6-diol has been studied by a variety of methods. Pure monomer heated under vacuum or in an inert gas atmosphere is found to polymerize readily, unlike material heated in air. X-ray diffraction reveals that samples anneal during polymerization. Initially, a long chain polymer is formed, but above 20% conversion a less perfect product is obtained. Measurements suggest a complex molecular rearrangement during the nonideal phase of polymerization. Possible models for this process are discussed.     

Synthesis and some properties of 2,3-dihydrofuro[2,3-b]quinol-4-one

The reaction of O-ethylbutyrolactonium tetrafluoroborate with ethyl anthranilate gave the corresponding imido ester, which undergoes cyclization to a furo[2,3-b]-quinol-4-one derivative when it is heated in a solution of sodium butoxide. When the latter product is heated in diphenyl oxide, it is converted to a furo[3,2-c]-quinol-2-one derivative.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 65–67, January, 1982.     

Electrochemical Detection of DNA Melting Curves by Means of Heated Biosensors

This article reports about the detection of DNA melting curves at heated electrochemical biosensors. Osmium tetroxide‐bipyridine‐labeled target oligonucleotides are hybridized with probe oligonucleotides immobilized on gold electrodes. Then, the gold electrode is successively heated in order to measure a complete melting curve consisting of alternating current voltammetric signals. Melting temperatures ?_m, determined at various ionic strengths and in dependence on different numbers of base pair mismatches, have been compared with those obtained by means of UV spectrophotometry. The proposed method holds great promise for the fast and easy parallel detection of nucleic acids sequences on selectively heated electrode arrays. A stringent hybridization temperature can be easily adjusted in order to discriminate base pair mismatches.     

Collagen absorption bands in heated and rehydrated dentine

The objective of this work is identifying changes in the collagen bands in heated and rehydrated dentine. We use bovine dentine slices that were heated in oven between 100 and 300 degrees C. The sample hydration was conducted in sodium chloride solution at 0.9 wt.%; the spectra were acquired by a Fourier transform infrared spectrometer in the spectral range of 4000-400 cm-1. Our results show a temperature range (T225 degrees C) where the collagen is denatured and no reversion is observed after rehydration. This work identifies an important characteristic that dentinal collagen can assume when the tissue is heated and rehydrated; these results indicate the denaturation temperature of dentinal collagen to be near 175-200 degrees C.     

Effect of water vapor pressure on the phase composition of lithium monoaluminates formed in the interaction of aluminum hydroxide and lithium carbonate

It is shown that the partial water vapor pressure affects the phase composition of lithium monoaluminates formed when aluminum hydroxide (gibbsite) and lithium carbonate are heated in air, in the atmosphere of helium, and in a dynamic vacuum. When the mixture is heated to 800°C in an air atmosphere with partial water pressure of 1300 Pa, a nearly single-phase lithium monoaluminate α-LiAlO₂ is formed. In the reaction in the atmosphere of helium, in which the partial water vapor pressure does not exceed 4 Pa, γ-LiAlO₂ is formed together with α-LiAlO₂, with the content of the former exceeding that produced in the reaction in air. When the mixture is heated under dynamic vacuum conditions with partial water vapor pressure lower than 0.1 Pa, mostly γ-LiAlO₂ is formed.     

Investigation of picramic acid and methylguanidine formation during the heated Jaffe' reaction

The present study has confirmed the formation of picramic acid and methylguanidine during the heated Jaffe' reaction. Picramic acid was isolated on thin-layer chromatography from 0.5:1 and 1:1 heated creatinine:picric acid molar ratio test solutions, but not for similarly performed 3:1 test solutions. A Dowex column was employed to isolate methylguanidine from 0.5:1 and 3:1 molar ratio test solutions. Methylguanidine was similarly isolated from a heated alkaline creatinine solution.     

Intramolecular rearrangement of N-acetylindoxyl oxime

It was established that N-acetylindoxyl oxime is converted to N-acetylindoxyl acetyloxime when it is heated to 50 ° C in a mixture of acetic acid and acetic anhydride. If the reaction is carried out by refluxing, N-acetyl-2-acetoxy- 3-acetam-idoindole, which undergoes rearrangement to 1,3-diacetyl-3-acetamidooxindole when it is heated, is also formed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1068–1070, August, 1980.     

微流动注射进样-加热雾室-等离子体质谱测定血清中的铂

开发了一种基于雾化室加热的微流动注射进样系统,并用于血清中Pt的测定。该进样系统由微量毛细管雾化器、加热微型雾化室、八通道十六孔多功能旋转阀、蠕动泵和注射泵组成。研究了雾化室尺寸、加热温度和采样环体积对信号强度的影响。当雾化室内径为9 mm、加热段长度为6 cm,雾化室温度90 ℃,采样环体积为5 μL时,195Pt的信号强度提高了2.31倍,同时信号精密度从5.1%降至2.2%,并得到峰形良好的信号峰。该进样系统的试样消耗小、灵敏度和检出限均优于常规进样系统。10次测定10 μg/L的Pt标准溶液和血清样品溶液,峰高的RSD分别为2.9%和3.3%。该进样系统测得10个血清中的Pt含量与常规进样系统的测试结果无显著差异,在样品量稀少的情况下具有良好的应用价值。     

The Procyanidin C1-Dependent Inhibition of the Hydrolysis of Potato Starch and Corn Starch Induced by Pancreatin

Procyanidins are contained in various foods, and their effects on starch hydrolysis have been reported. In Japan, black soybeans, which contain a trimeric procyanidin, procyanidin C1 (proC1), are cooked with rice and used to prepare dumplings. In this study, the effects of proC1 on the pancreatin-induced formation of reducing sugars and starch hydrolysis were studied using potato starch and corn starch. ProC1 inhibited both reactions; the inhibition was greater in potato starch than corn starch when added to heated potato starch and corn starch. When heated with proC1, its inhibitory effects decreased, especially in potato starch, suggesting the important role of proC1 itself for the inhibition of potato starch hydrolysis. ProC1 also inhibited the hydrolysis when added to heated, longer amylose (average molecular weight: 31,200), and the inhibition decreased when heated with the amylose. On the other hand, proC1 could not inhibit the hydrolysis when added to heated, shorter amylose (average molecular weight: 4500), but could when heated with the amylose, suggesting the important role of the degradation products of proC1 for the inhibition. We discuss the mechanism of the proC1-dependent inhibition of amylose hydrolysis, taking the molecular weight into account.     

A rapid method for the microdetermination of nitrogen in organic compounds using a flushed-oxygen combustion tube

A micromethod to determine nitrogen in organic compounds of 1–1.5 mg has been studied by the combustion method where oxygen is flushed into an empty combustion tube heated at 850 °C. The flushing nozzle is consisted of two silica filters in a L-tube and oxygen flowing out of the nozzle rapidly oxidizes the organic vapor gasified in a sample heater. Excess oxygen and nitrogen oxides are absorbed and reduced with reduced copper heated at 500–600 °C.     

Shadow spectral imaging of absorbing layers in a transversely heated graphite atomizer: Part 2. Molecules and condensed-phase species

The dynamics of formation and dissipation of chloride, nitrate and sulfate matrix vapors in a transversely heated graphite tube atomizer (THGA) with and without integrated platform was investigated with the use of multi-channel atomic absorption spectrometry and the shadow spectral imaging technique. It is shown that non-uniform heating of the tube walls and platform in the furnace radial cross-section causes vapor transfer from atomizer bottom to less heated sides of the tube and platform. This transfer in the atomizer cross-section can be an additional reason for lower level of matrix interferences in the THGA and is a prerequisite for explosive atomization of some elements that appear as absorbance spikes. The cross-sectional structures of molecular layers and the cloud of condensed phase particles are highly inhomogeneous, resulting in absorbance gradients up to 0.2–0.5 mm^− 1. These structures differ significantly from those observed earlier in end-heated atomizers. Local vortices of the sheath gas, toroid-shaped and bridge-like structures of vapor layers were observed in the atomizer volume. The role of light scattering on the finally dispersed condensed phase particles in the transverse heated furnace is greater than that in the end heated atomizers because of near axis location of the cloud.     

Structural evolution of turbostratic carbon: Implications in H2 storage

Structural evolution of turbostratic carbon samples as a function of annealing temperature has been investigated in detail using small angle X-ray scattering (SAXS), solid state nuclear magnetic resonance (NMR) and Raman spectroscopic techniques. From these studies, it is established that, samples heated at lower temperatures (700 °C and 800 °C) consist carbon particles with rough surfaces forming structure of surface fractal in nature. Whereas the sample heated at higher temperature (900 °C) consists of larger clusters with nearly smooth surface as well as smaller size particles forming dense mass fractal structure. For this sample, solid state NMR and Raman Spectroscopic studies indicate an increased extent of overlapping of 2p_z orbital of carbon atoms due to improved long range ordering and clustering. Hydrogen adsorption studies further substantiated that energetically more homogeneous surface exists for particles of 900 °C heated sample as compared to those of 700 °C and 800 °C heated samples. A highest hydrogen storage capacity of 0.152 H/M has been observed at 123 K and 45 bar pressure for the sample heated at 900 °C.     

A study of atomic absorption and atomic fluorescence atomization systems as detectors in the gas chromatographic determination of lead

The suitability of various atomic absorption and atomic fluorescence atomizing systems connected to a gas chromatograph is compared for the determination of alkyl lead compounds. An electrothermally heated graphite tube gives the highest sensitivity but quartz tubes heated either in an air-acetylene flame or by electrical resistance wire provide adequate sensitivity for most applications. A “solvent peak” absorption thought earlier to be due to organic molecular absorption of radiation at the lead wavelength was shown to be due to deposition and remobilization of lead.     

Morpholine derivatives

The β-oxide ring of 3-alkyl-3-(N-morpholinomethyl)oxacyclobutanes is opened to give methiodides or hydrohalide salts, respectively, of 2-alkyl-2-(N-morpholinomethyl)-3-halopropanol when they are heated with methyl iodide in methanol under pressure or heated with hydrohalic acids. When two morpholinomethyl groups are present in the 3 position of the oxacyclobutane ring, it is not opened.     

The Microwave Direct Heating of Zeolite FAU in an Open System

Zeolite FAU was heated directly by microwave irradiation at 2450 MHz is in open system without special loading materials. It was discovered that zeolite X was heated to 1473K about 90 seconds at power output of 400W. HY type zeolite was also heated to 1373K although in needed relative long time (about 11 minutes). Influences of exchangeable cations and adsorbed substances on zeolite′s ability to absorb microwaves were also discussed.