Screening of biomarkers in rat urine using LC/electrospray ionization-MS and two-way data analysis

Biofluids, like urine, form very complex matrixes containing a large number of potential biomarkers, that is, changes of endogenous metabolites in response to xenobiotic exposure. This paper describes a fast and sensitive method of screening biomarkers in rat urine. Biomarkers for phospholipidosis, induced by an antidepressant drug, were studied. Urine samples from rats exposed to citalopram were analyzed using solid-phase extraction (SPE) and liquid chromatography mass spectrometry (LC/MS) analysis detecting negative ions. A fast iterative method, called Gentle, was used for the automatic curve resolution, and metabolic fingerprints were obtained. After peak alignment principal component analysis (PCA) was performed for pattern recognition, PCA loadings were studied as a means of discovering potential biomarkers. In this study a number of potential biomarkers of phospholipidosis in rats are discussed. They are reported by their retention time and base peak, as their identification is not within the scope of the study. In addition to the fact that it was possible to differentiate control samples from dosed samples, the data were very easy to interpret, and signals from xenobiotic-related substances were easily removed without affecting the endogenous compounds. The proposed method is a complement or an alternative to NMR for metabolomic applications.     

Nitrous oxide emission as affected by liming an acidic mineral soil used for arable agriculture

The effect of liming an acidic mineral soil (Dystric Nitosol from southern China), used for arable agriculture, on N₂O emission was studied in an incubation experiment. After the soil pH had been raised from pH 4.4 to 5.2, 6.7 and 8.1, soil samples were either amended with NH₄ ⁺ and incubated aerobically, favoring nitrification or, after application of NO₃ ^–, the incubation took place under anaerobic conditions, favoring denitrification. Gas sampling for N₂O determination and soil analyses were performed at regular intervals up to 13 days. Under nitrification conditions only small N₂O emission rates were observed (max. 6 g N kg^–1 d^–1) with significant differences between high and low pH values during the first 2 days of incubation. The nitrifying activity was low, even with high pH, and this, together with good aeration conditions, could partly explain the small N₂O evolution. During denitrification, however, cumulative N₂O emissions reached much higher values (1600 g N kg^–1 in comparison to 40 g N kg^–1 under nitrification conditions). N₂O emission during denitrification was significantly enhanced by increasing soil pH. Under alkaline conditions (pH 8.1) a large nitrite accumulation occurred, which was in line with the highest nitrate reductase activity determined in this treatment. The limited availability of organic carbon is probably the main reason for the absence of further reduction of NO₂ ^– to N₂O or N₂. At pH 6.7 the total N₂O emission was slightly higher than at pH 8.1, although the start of pronounced emissions was retarded and only small amounts of NO₂ ^– accumulated. Acid soil conditions caused either negligible (pH 4.4) or only small (pH 5.2) N₂O emissions. It can be concluded that these kinds of soil, used alternatively for production of upland crops or paddy rice, are prone to high N₂O emissions after flooding, particularly under neutral to alkaline conditions. In order to avoid major N₂O evolution and accumulation of nitrite, which can be leached into groundwater, the pH should not be raised to values above 5.5–6.     

Process conditions in X-ray lithography for the fabrication of devices with sub-micron feature sizes

This article describes the fabrication of polymer structures with lateral dimensions in the sub-micron regime using hard X-rays (λ_c ≈ 0.4 nm) from the electron storage ring ANKA. Spincoated polymethylmethacrylate (PMMA) grades have been analyzed with respect to development rates and contrast. The contrast has been determined to be constant over a wide dose regime but rapidly decreases for dose values below 1 kJ/cm³. Films with a thickness from 2 to 11 μm have been patterned using a high resolution X-ray mask consisting of 2 μm thick gold absorbers on a suspended 1 μm thick silicon nitride membrane. The fabrication of sub-micron X-ray lithography structures with feature sizes down to 400 nm is confined by the mechanical parameters of the resist material and the process conditions. Surface tension after development limits the achievable aspect ratio of isolated pillars and walls, depending on the actual resist height. PMMA structures have been successfully used as template for electroplating of 1 μm thick gold to demonstrate the fabrication capability of sub-micron scale metal parts.     

Experimental Modelling using Low Melting Point Metallic Melts: Relevance for Metallurgical Engineering

This paper describes model experiments with liquid metals of low melting point as an important tool to investigate the flow structure and related transport processes in melt flows being relevant for metallurgical applications. Three examples have been selected to demonstrate the benefit of such experiments, namely the electromagnetic stirring of a metallic melt in a pool, the directional solidification of Al‐Si alloys under the influence of an electromagnetically driven flow and the behaviour of a liquid metal bubble plume if a vertically travelling field is applied. Results of flow measurements are presented and the relevance for metallurgical processes is discussed.     

Grafting of titanium dioxide microspheres with a temperature‐responsive polymer via surface‐initiated atom transfer radical polymerization without the use of silane coupling agents

Titania microspheres with narrow size distribution and diameters of about 1 µm were prepared and subsequently functionalized using surface‐initiated atom transfer radical polymerization (ATRP) of N‐isopropylacrylamide. The ATRP initiator was immobilized on the particle surface via acylation of surface hydroxyl groups with α‐bromoisobutyryl bromide. Subsequently, an established ATRP reaction system was used for the preparation of titania surface‐grafted poly(N‐isopropylacrylamide) (PNiPAAm). Characterization was performed with electron microscopies, X‐ray diffraction, infrared spectroscopy and dynamic light scattering. It was found that the particle size in aqueous dispersions changed reversibly with temperature as expected for a shell of PNiPAAm, a polymer with a lower critical solution temperature at 32 °C. This confirmed the successful preparation of functional, stimuli‐responsive TiO₂ microparticles via a straightforward controlled surface‐initiated polymerization method.     

Fully-Naphthalenoid Hydrocarbons: Enumeration and Classification

Abstract

A fully-naphthalenoid system (or simply fully-naphthalenoid) is a benzenoid where all vertices can be covered by disjoint naphthalene units. Invariants of these systems are studied with special emphasis on the C_nH_s formulae. An extensive enumeration of fully-naphthalenoids by means of a computer program is reported. A detailed classification of the numbers includes the symmetry distribution and an enumeration of the C_nH_s isomers. The forms of the smallest fully-naphthalenoids are displayed together with their Kekulé structure counts.     

Fully-Naphthalenoid Hydrocarbons and their Conjugation Modes

Abstract

A fully-naphthalenoid hydrocarbon (FUN) is a benzenoid hydrocarbon whose all π-electrons can be (formally) grouped into disjoint naphthalene-units. The cyclic conjugation in FUNs is studied by means of the energy-effects of their various cycles. It is found that the dominant conjugation modes in FUNs are those involving the 6- and 10-membered cycles of the “full” naphthalene fragments. The cycles belonging to the “empty” domains of a FUN have significantly smaller energy-effects.     

Managing the five tensions of IT-enabled decision support in turbulent and high-velocity environments

This chapter examines issues concerned with supporting managers and organizations with information and communication technologies as they decide and act in turbulent and high-velocity environments. In particular, the chapter identifies five key tensions in this context: (1) the tension between the need for quick decisions and the need for analytical decision processes; (2) the tension involving managerial need for action and the need for the safest execution of decisions that may be bold and risky; (3) the tension around empowering middle managers and management teams at various organizational levels in the midst of powerful and impatient top executives; (4) the tension between programmed, quick-action learning loops and the increased requirement for emergence and improvisation; and (5) the tension between expending effort to eliminate the digital divide with other organizations versus finding expedient ways to communicate through heterogeneous digital infrastructures. Each of the tensions, and how it can be managed, is illustrated through a case example. The chapter ends by suggesting that the management of these critical tensions needs to be fused into the day-to-day fabric of management practices for decision support processes. This article is part of the “Handbook on Decision Support Systems” edited by Frada Burstein and Clyde W. Holsapple (2008) Springer.     

Do infants segment words or recurring contiguous patterns?

Eight experiments tested the hypothesis that infants' word segmentation abilities are reducible to familiar sound-pattern parsing regardless of actual word boundaries. This hypothesis was disconfirmed. in experiments using the headturn preference procedure: 8.5-month-olds did not mis-segment a consonantvowel- consonant (CVQ word (e.g., dice) from passages containing the corresponding phonemic pattern across a word boundary (C#VC#; "cold ice"), but they segmented it when the word was really present ("roll dice"). However, they did not segment the real vowel-consonant (VC) word (ice in "cold ice") until 16 months. Yet, at that age, they still did not false alarm on the straddling CVC word. Thus, infants do not simply respond to recurring phonemic patterns. Instead, they are sensitive to both acoustic and allophonic cues to word boundaries. Moreover, there is a sizable developmental gap between consonant and vowel-initial word segmentation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)