Christian V. Stevens

Bio: Christian V. Stevens is an academic researcher from Ghent University. The author has contributed to research in topics: Ionic liquid & Bicyclic molecule. The author has an hindex of 45, co-authored 467 publications receiving 11742 citations. Previous affiliations of Christian V. Stevens include Katholieke Universiteit Leuven & University of Minnesota.

Synthesis of 2-phosphonopyrroles via a one-pot RCM/oxidation sequence

Abstract: A four-step synthesis of 2-phosphonopyrroles is presented starting from suitable aldehydes. The key step in the synthesis involves a one-pot ring-closing metathesis/oxidation sequence of a functionalized α-aminoalkenyl phosphonate. Notwithstanding the presence of a nucleophilic nitrogen atom and high substitution patterns in the substrate, the results of the RCM reaction are excellent using mild reaction conditions. Furthermore, a synergism is observed between the RCM catalyst and the oxidizing agent, causing higher oxidation rates and allowing reaction for substrates that normally fail to ring close under standard RCM conditions.

Characterization of French Coriander Oil as Source of Petroselinic Acid.

Abstract: Coriander vegetable oil was extracted from fruits of French origin in a 23% yield. The oil was of good quality, with a low amount of free fatty acids (1.8%) and a concurrently high amount of triacylglycerols (98%). It is a rich source of petroselinic acid (C18:1n-12), an important renewable building block, making up 73% of all fatty acids, with also significant amounts of linoleic acid (14%), oleic acid (6%), and palmitic acid (3%). The oil was characterized by a high unsaponifiable fraction, comprising a substantial amount of phytosterols (6.70 g/kg). The main sterol markers were β-sitosterol (35% of total sterols), stigmasterol (24%), and Δ7-stigmastenol (18%). Squalene was detected at an amount of 0.2 g/kg. A considerable amount of tocols were identified (500 mg/kg) and consisted mainly of tocotrienols, with γ-tocotrienol as the major compound. The phospholipid content was low at 0.3%, of which the main phospholipid classes were phosphatidic acid (33%), phosphatidylcholine (25%), phosphatidylinositol (17%), and phosphatidylethanolamine (17%). About 50% of all phospholipids were non-hydratable. The β-carotene content was low at 10 mg/kg, while a significant amount of chlorophyll was detected at about 11 mg/kg. An iron content of 1.4 mg/kg was determined through element analysis of the vegetable oil. The influence of fruit origin on the vegetable oil composition was shown to be very important, particularly in terms of the phospholipids, sterols, and tocols composition.

Dialdehyde carboxymethyl cellulose cross-linked chitosan for the recovery of palladium and platinum from aqueous solution

Abstract: Platinum (Pt) and palladium (Pd) have widespread applications, such as in catalysts, jewelry, fuel cells, and electronics because of their favorable physical and chemical properties. Recovery of Pt and Pd from secondary sources is of great concern due to the increased market demand and limitation of the natural reserves of these precious metals. The aim of this research is to achieve recovery of Pt and Pd ions from dilute aqueous solution using dialdehyde of carboxymethyl cellulose (DCMC) crosslinked chitosan (Ch-DCMC). The DCMC was prepared by periodate oxidation of carboxymethyl cellulose (CMC). Both the DCMC and Ch-DCMC were characterized before and after Pt or Pd adsorption using Fourier-transformed infrared (FTIR) spectroscopy, X-ray powder diffraction (XRPD), and scanning electron microscopy (SEM). The effect of cross-linking ratios of chitosan and DCMC (1:1, 1:0.8, 1:0.5, 1:0.25 and 1:0.1) on the Pt and Pd recovery was studied. The optimal cross-linking ratio was found to be 1:0.25 (chitosan: DCMC) with maximum adsorption capacity of 80.8 mg/g Pt and 89.4 mg/g Pd. High selectivity for Pt and Pd compared to base metals and common anions was achieved.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Production of first and second generation biofuels: A comprehensive review

Abstract: Sustainable economic and industrial growth requires safe, sustainable resources of energy. For the future re-arrangement of a sustainable economy to biological raw materials, completely new approaches in research and development, production, and economy are necessary. The ‘first-generation’ biofuels appear unsustainable because of the potential stress that their production places on food commodities. For organic chemicals and materials these needs to follow a biorefinery model under environmentally sustainable conditions. Where these operate at present, their product range is largely limited to simple materials (i.e. cellulose, ethanol, and biofuels). Second generation biorefineries need to build on the need for sustainable chemical products through modern and proven green chemical technologies such as bioprocessing including pyrolysis, Fisher Tropsch, and other catalytic processes in order to make more complex molecules and materials on which a future sustainable society will be based. This review focus on cost effective technologies and the processes to convert biomass into useful liquid biofuels and bioproducts, with particular focus on some biorefinery concepts based on different feedstocks aiming at the integral utilization of these feedstocks for the production of value added chemicals.

Chitosan chemistry and pharmaceutical perspectives.

Abstract: Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S. A. S. Nagar,Mohali, Punjab-160 062, India, Institute of Biochemistry, Faculty of Medicine, Polytechnic University, Via Ranieri 67, IT-60100 Ancona, Italy,Green Biotechnology Research Group, The Special Division for Human Life Technology, National Institute of Advanced Industrial Science andTechnology, 1-8-31 Midorigaoka, Ikeda, Osaka-563-8577, Japan, and Department of Medicinal Chemistry & Natural Products,The Hebrew University of Jerusalem, School of Pharmacy-Faculty of Medicine, Jerusalem 91120, IsraelReceived March 2, 2004