高寒地区浅基础埋深问题

运用工程实例论述了影响高寒地区浅基础埋深的重要因素, 提出了基础埋深的具体计算方法。     

Electrode Processes Involving Associates of CoNTA– and CoEDTA2–with Hexacyanoferrate Ions in Aqueous Solutions

Ionic association in K₃Fe(CN)₆solutions containing cobalt(II) ethylenediaminetetraacetate and nitrilotriacetate is studied by voltammetry, spectrophotometry, and Mössbauer, IR, and ⁵⁹Co NMR spectroscopy techniques. Situations where the inner-sphere association leads to the formation of solid products on electrodes (conducting films among them) are revealed.     

Melanin‐Containing Films: Growth from Dopamine Solutions versus Layer‐by‐Layer Deposition

Films formed by oxidation of dopamine are of interest for functionalisation of solid–liquid interfaces owing to their versatility. However, the ability to modulate the properties of such films, for example, permeability to ionic species and the absorption coefficient, is urgently needed. Indeed, melanin films produced by oxidation of dopamine absorb strongly over the whole UV/Vis part of the electromagnetic spectrum and are impermeable to anions even for a film thickness as low as a few nanometers. Herein we combine oxidation of dopamine to produce a solution containing dopamine–melanin particles and their alternating deposition with poly(diallyldimethylammonium chloride) to produce films which have nearly the same morphology as pure dopamine–melanin films but are less compact, more transparent and more permeable to ferrocyanide anions.     

HPLC-MS-MS法测定水体中残留的氨基甲酸酯类农药

应用高效液相色谱-串联质谱(HPLC-MS-MS)联用技术,建立了检测水体中氨基甲酸酯类农药残留的方法。水样经氨基柱固相萃取,二氯甲烷洗脱,梯度流动相洗脱,电喷雾正离子(ESI+)模式采集、选择反应性监测模式(SRM)对定性、定量离子进行MS/MS测定。5种氨基甲酸酯类农药在5～200ng/L范围内线性关系良好,回收率为80%～92%,相对标准偏差均小于10%,方法检出限分别为:异丙威和仲丁威为1.4ng/L,克百威和甲萘威为1.5ng/L,恶虫威为1.6ng/L。该方法适用于水体中氨基甲酸酯类农药残留的检测。     

Dynamics of a magnetic domain system upon parametric excitation

The occurrence of translational motion in the domain system in a ferrite plate under harmonic parametric action is investigated. The domain dynamics is described on the basis of the numerical solution of differential equations for a system of connected oscillators. Transition scenarios from oscillatory to translational motion are described, depending on the changes in the nonlinearity constant and damping parameter for various numbers of oscillators.     

Determination of ammonia in the air using piezoelectric resonance sensors coated with humic acids

Natural macromolecular compounds, humic acids (HA), have been used to form gas-sensitive layers of piezoelectric resonance gravimetric sensors. HA have been extracted from humus using alkaline extraction and purified by electrodialysis through ion-exchange membranes. Species have been deposited onto the electrode surface of piezoelectric quartz resonators by air-spraying their aqueous solutions, the layer thickness being 100–200 nm. In determining ammonia with the sensor obtained on the basis of purified HA species, the detection limit is ∼10 mg/m³. Gas-sensitive layers on the basis of humic acids are more stable as compared to the conventionally used gas-sensitive layers based on pyridoxine hydrochloride or ascorbic acid.