Detection and quantification of lanthanide complexes in cell lysates by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Gadolinium (III) complexes are under intense scrutiny as contrast agents for magnetic resonance imaging. Although currently used mainly as extracellular agents, there is a growing interest to exploit their contrast enhancing ability in the intracellular environment. To ascertain the preservation of their chemical integrity upon the intracellular entrapment, it is necessary to have a method for their dosage in the cell lysates. Herein, a mass spectrometric method for detection and quantification of gadolinium complexes in cell lysates is reported. The detection by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) was carried out by using a non-acidic matrix (2,4,6-trihydroxyacetophenone), which does not allow any leakage of gadolinium from the complex. Quantification has been possible by using as an internal standard an ytterbium complex with the same ligand of the analyte. Ytterbium was chosen because, among the lanthanides, it is the one with the isotopic distribution pattern the most similar to that of gadolinium. Sensitivity was enough to detect low micromolar quantities of a cationic complex and high micromolar quantities of a neutral complex in cell lysates of rat hepatoma cells. In the case of anionic complexes, sensitivity was too low for quantitative analysis. To the best of our knowledge, this is the first report concerning the quantification of metal complexes by MALDI-TOF-MS.     

From hypergravity to microgravity: Choosing the suitable simulator

Cardiovascular system functions are impaired in altered gravity conditions. In particular endothelial cells play a major role being responsible for the integrity of the vascular wall. Due to obvious difficulties in performing continuous and exhaustive experiments in space, most of the available data have been obtained so far using various simulators of hypergravity and microgravity (µg) conditions. The consistency of the data resides on the reliability of the simulator, being a critical point in the development of the research. We exposed the cell cultures to 1) hypergravity (launch condition) using MidiCAR at Dutch Experiment Support Center (DESC, NL); 2) simulated µg using the Rotating Wall Vessel (RWV) and the Random Positioning Machine (RPM). We used two different cellular models: human umbilical vein endothelial cells (HUVEC) and human leukocytes (U937). Only few experiments on cells using RPM have been reported. To assess the RPM best operative parameters we considered data from experiments in space on U937 as reference standard. Differently, cultures in modelled µg using RWV have been extensively reported. Our data on HUVEC indicate that the two µg simulators provide analogous results in terms of proliferation and cytoskeletal organization. Finally, to investigate the effects of spaceflight on different human cells, we developed a spaceflight-like protocol consisting of an initial hypergravity phase (launch), followed by a µg simulation (orbital flight). Using this protocol, results show that hypergravity limits in our models the effects on proliferation induced by modelled µg.     

Three-dimensional acquisition of large and detailed cultural heritage objects

Cultural heritage digitization is becoming more common every day, but the applications discussed in the literature address mainly the digitization of objects at a resolution proportional to the object size, using low resolution for large artifacts such as buildings or large statues, and high resolution for small detailed objects. The case studied in this paper concerns a huge physical model of imperial Rome (16 × 17.5 m) whose extremely small details forced the use of high resolution and low noise scanning, in contrast with the long range needed. This paper gives an account of the procedures and the technologies used for solving this “contradiction”.     

Further Results on the Observability of Quantum Systems Under General Measurement

In this paper, we present a collection of results on the observability of quantum mechanical systems, in the case the output is the result of a discrete nonselective measurement. By defining an effective observable, we extend previous results, on the Lie algebraic characterization of observable systems, to general measurements. Further results include the characterization of a ‘best probe’ (i.e. a minimally disturbing probe) in indirect measurement and a study of the relation between disturbance and observability in this case. We also discuss how the observability properties of a quantum system relate to the problem of state reconstruction. Extensions of the formalism to the case of selective measurements are also given.     

SWiMNet: A Scalable Parallel Simulation Testbed for Wireless and Mobile Networks

We present a framework, called SWiMNet, for parallel simulation of wireless and mobile PCS networks, which allows realistic and detailed modeling of mobility, call traffic, and PCS network deployment. SWiMNet is based upon event precomputation and a combination of optimistic and conservative synchronization mechanisms. Event precomputation is the result of model independence within the global PCS network. Low percentage of blocked calls typical for PCS networks is exploited in the channel allocation simulation of precomputed events by means of an optimistic approach.Various experiments were conducted to study the performance and scalability of SWiMNet using a realistic mobility model and executed on a cluster of workstations. Experimental results indicate that our parallel simulation model yields good speedup, and significantly reduces the execution time compared to a sequential implementation. Finally, an analytical study of our PCS simulation model is also presented and compared with the experimental results. Our model is found to be consistent with the analytical study.     

Performance of W-InSb Metal-Semiconductor Point-Contact Diodes as Detectors and Mixers in the Near Infrared

Metal-Insulator-Metal (MIM) and Schottky-barrier diodes have been used extensively in the past years as harmonic generators and mixers for frequency measurements in the spectral range from the far-infrared to the visible. MIM diodes present a very low fabrication cost and are easy to handle, while Schottky diodes are mechanically more stable and long-lived. In the present work we discuss the performance of a metal-semiconductor point-contact diode for the radiation around 1 μm. This device, which may be viewed as a hybrid between a MIM and a Schottky diode, combines the simplicity and easiness of fabrication of the MIM diode with the stability and the long contact life typical of the Schottky diode. It proved to be very efficient even for visible light.     

Q‐factor evaluation,design and accurate EM performance of multilayer dielectric filters

In this contribution we present the design of an optical dielectric multilayered filter by using a transmission‐line prototype. Each resonator of the prototype is realized by means of a stack of dielectric layers by equating the Q‐factor of the stack with that of the corresponding resonator of the prototype. We then compare the analytical results with numerical ones obtained by the finite element method (FEM). We extend the theory to a structure formed by periodic multilayer resonators. Copyright © 2006 John Wiley & Sons, Ltd.     

Asymmetric Sulfoxidation of Thioethers with Hydrogen Peroxide in Water Mediated by Platinum Chiral Catalyst

Easy stereoselective oxidation of prochiral aryl alkyl sulfides 2 to the corresponding sulfoxides can be achieved in water‐surfactant medium with inexpensive hydrogen peroxide mediated by the chiral platinum diphosphine complex {[(R)‐BINAP]Pt(μ‐OH)}₂(BF₄)₂ ( 1 ). Remarkable key features of general interest are (i) easy isolation of the products from catalyst by simple diethyl ether/water‐surfactant two phase separation, (ii) catalyst loading as low as 1% mol, (iii) good yields, sulfoxide 3 to sulfone 4 ratio up to 200 : 1 and enantioselectivities up to 88%, (iv) mild experimental conditions.     

植物油的氧化及其对淬火特性的影响

传统上,矿物油是常用淬火剂中最重要的一类淬火剂。然而,它们在本质上缺乏环保性,又有毒性,再从长期低价供应角度考虑,有必要寻找新的替代介质。石油制品油的淬火特性与其成分很有关系,因而受其氧化降解性能的限制。由于不断暴露在钢与油接触面问相对较高的温度中,石油制品油遭受热降解和氧化降解,使得其淬火特性发生明显变化。因此,淬火特性是任何一种可选择的淬火介质都必须要检验的一个非常重要的性能参数。可供选择的一类液态物质为植物油,它们具有典型的生物降解特性并且无毒。然而,植物油具有相对较差的抗氧化稳定性能,因此测定氧化对其淬火特性的潜在影响具有重要意义。本文报导的结果仅是这项巨大研究中的第一步,在这项工作中,对不受禁止的植物油的试验是在实验室设备上进行的,以前报告的促使石油制品油早期氧化的过程接近实际使用条件。依照ASTM D 6200标准,使用粘度计、红外线分光镜、^13CMR分光镜以及冷却曲线特性测定方法对所研究的液态植物油进行了性能检测并和典型的石油制品油作了成分比较。所得的结果表明,作为淬火介质,植物油是有前景的石油制品油的替代品,但在商业上要可行,同时必须使用适当的抗氧化剂。