Effects of GaAs and Ga2O3 on magnetometric behavior of iron oxide particles in rabbit lungs

Intratracheal instillation of a GaAs suspension has been histopathologically shown to induce a diffuse pulmonary response. In the present study, magnetometry was used to evaluate the effects of intratracheally instilled GaAs and Ga₂O₃ on the behavior of externally magnetized iron oxide (Fe₃O₄) particles instilled in rabbit lung. Magnetometric evaluation of the effects of GaAs in rabbits dosed with 30 mg or 300 mg per animal showed a significantly decreased relaxation of iron oxide particles at 1, 3, 7, 14, 21 and 28 days following instillation compared with the controls. On the other hand, in the rabbits exposed to Ga₂O₃, significantly reduced decay constants were observed only on the first and third days following instillation. Relaxation indicates a rapid decrease of remanent magnetic field following magnetization of the lungs due to random rotation of phagocytosed iron oxide particles in macrophages. Clearance of the iron oxide particles was measured by serial determinations of the remanent magnetic field at the end of magnetization estimated from relaxation curves. Clearance was significantly impaired at 14, 21 and 28 days after instillation in rabbits exposed to both doses of GaAs. Slightly delayed clearance was also observed in rabbits exposed to Ga₂O₃. Histological examination of lungs instilled with GaAs indicated active phagocytosis of GaAs and iron oxide particles by pulmonary macrophages, as well as pneumonocytes hyperplasia with marked thickening of the alveolar walls. Minimal histological changes with retention of iron oxide particles were found in the lungs exposed to Ga₂O₃.     

Iodination of organotrifluoroborates: synthesis of vinyl and alkynyl iodides

Vinyl- and alkynyltrifluoroborates are rapidly converted to vinyl and alkynyl iodides under mild conditions using sodium iodide in the presence of chloramine-T. The reaction is stereospecific and proceeds in excellent yield.     

Comparative chronic toxicity,including tumorigenicity,of gallium arsenide and arsenic trioxide intratracheally instilled into hamsters

Chronic toxicity, including tumorigenicity, of gallium arsenide (GaAs) and arsenic trioxide (As₂O₃) were studied using Syrian golden hamsters given intermittent intratracheal instillations. GaAs particles (0.25 mg × 15 times/animal) were likely to produce relatively severe lung damage and the survival of the animals was shortened significantly compared with a control group. The tumor incidence of each group examined was GaAs (3.3%), As₂O₃ (3.3%) respectively, at a dose of 3.75 mg total metal given during 15 weeks. In this experiment, both arsenic trioxide and gallium arsenide had no apparent carcinogenicity or tumorigenicity.     

Palladium‐Initiated Radical Cascade Stereoselective Iodofluoroalkylation/Cycloisomerization of Ene‐vinylidenecyclopropanes

A novel and convenient palladium‐initiated radical cascade stereoselective iodofluoroalkylation/cycloisomerization of ene‐vinylidenecyclopropanes with fluoroalkyl iodides has been developed. The reaction proceeds under mild reaction conditions with high atom economy and stereoselectivity, thereby allowing an efficient access to a variety of difluoromethylated or perfluoroalkylated pyrrolidines tethered with an alkyl iodide. Two plausible radical pathways for the transformation have been proposed on the basis of the results of control experiments and previous reports, which in one case it was thought that palladium(0) was an initiator rather than a catalyst.     

碘代烷烃在532 nm激光作用下多光子电离解离机理

利用５３２ｎｍ的激光对碘代烷烃（碘甲烷、碘乙烷、碘代正丙异丙烷）分子作了多光了电离解离（ＭＰＩＤ）质谱（ＭＳ）研究,在５３２ｎｍ激光作用下,ＣＨ３Ｉ分子吸收５３２ｎｍ激光双光子的能量,进入Ａ带的ＩＡ２态,继续吸收光子上泵浦至电离态形成母体离子ＣＨ３Ｉ,然后再形成碎片离子;而其它几个碘代烷烃吸收双光子的能量进入Ａ带后均形成中性碎片,中性碎片再吸收光子经一系列电离解离形成碎片离子,此外,本文还通过对同     

The epitaxial growth of gallium arsenide using triethylarsine

The thermal decomposition of triethylarsine (TEAs) has been studied. It decomposes at a lower temperature than arsine (AsH₃). The decomposition proceeds via a radical process at a temperature above 700°C. Epitaxial growth using TEAs has been investigated. A gallium arsenide (GaAs) layer with good morphology was obtained, but the layer was found to contain a considerable amount of carbon impurity originating from TEAs. The use of TEAs with 10% AsH₃ or with 20% ammonia (NH₃) apparently improves the quality of GaAs layer. A possible scheme for reducing carbon incorporation is discussed.     

Photocontrolled Iodine‐Mediated Reversible‐Deactivation Radical Polymerization: Solution Polymerization of Methacrylates by Irradiation with NIR LED Light

Herein, near‐infrared (NIR) photocontrolled iodide‐mediated reversible‐deactivation radical polymerization (RDRP) of methacrylates, without an external photocatalyst, was developed using an alkyl iodide (e.g., 2‐iodo‐2‐methylpropionitrile) as the initiator at room temperature. This example is the first use of a series of special solvents containing carbonyl groups (e.g., 1,3‐dimethyl‐2‐imidazolidinone) as both solvent and catalyst for photocontrolled RDRP using long‐wavelength (λ_max=730 nm) irradiation. The polymerization system comprises monomer, alkyl iodide initiator, and solvent. Well‐defined polymers were synthesized with excellent control over the molecular weights and molecular weight distributions (M_w/M_n<1.21). The living features of this system were confirmed by polymerization kinetics, multiple controlled “on‐off” light switching cycles, and chain extension experiments. Importantly, the polymerizations proceeded successfully with various barriers (pork skin and A4 paper), demonstrating the advantage of high‐penetration NIR light.     

Trace analysis of gallium arsenide by selective evaporation of the matrix with bromine vapours

Gallium arsenide samples are analyzed by graphite furnace AAS after the selective evaporation of the matrix elements as bromides with bromine vapours in a simple apparatus. The evaporation step is carried out at 280–300 ° C and it is accomplished for 0.5 g sample within 1 h. Reproducibilities of 5 to 20% were obtained. Detection limits (3 s, in ng/g) are 20 (Fe), 5.0 (Ca), 3.0 (Mg), 2.0 (Ni, Cu), 1.0 (Al), 0.5 (Pb, Co), 0.2 (Mn, Cr).     

A simple one-pot synthesis of hydroxylated and carboxylated aryl alkyl sulfides from various bromobenzenes

A simple one-pot synthesis of aryl alkyl sulfides from various bromobenzenes containing a hydroxy, hydroxymethyl, hydroxyethyl, and carboxylic acid group at -o, -m, and -p positions is reported here. The reaction proceeds through, in sequence, in situ protection of the hydroxy or carboxylic acid group by reaction with a Grignard reagent, lithium-halogen exchange, the formation of lithium thiolates, and the nucleophilic attack of lithium thiolates on various electrophiles without isolation of the thiolates, in one vessel. This procedure required a very short reaction time (1-1.5 h) and gave the corresponding sulfides in 75-97% yields.     

Regiocontrolled synthesis of highly-functionalized fused imidazoles: a novel synthesis of second generation LFA-1 inhibitors

A new and reliable route to a new class of LFA-1 inhibitors such as (2) has been developed. A key aspect of this route is the transformation of amino amide 5 into iodide 3 in four steps. Iodide 3 is a key advanced intermediate used in the synthesis of all second-generation 1H-imidazo[1,2-α]imidazol-2-one LFA-1 inhibitors.     

A metal-free three components procedure for the synthesis of perfluoroalkyl substituted amidines

An interesting multicomponent reaction for the synthesis of perfluoroalkyl substituted amidines has been developed. By using perfluoroalkyl iodides, tert-butyl isocyanides and amines as the substrates, the reactions proceed via somophilic isocyanide insertion. In this catalytic system, no transition-metal catalyst, additional ligands and additives were required. The reaction proceed smoothly and a variety of desired amidines were obtained in moderate to excellent yields.     

Photolysis of 1‐C4H9I and 2‐C4H9I at 266 nm: Direct Observation of the Effect of Branching on the Photodissociation Mechanism

Velocity ion imaging (see figure) is used to analyze the photodissociation mechanism of 1‐C₄H₉I (left image) and 2‐C₄H₉I (right image) at 266 nm. For 2‐C₄H₉I, a new channel for formation of I and I* atoms is observed. It is attributed to the repulsive mode along the C? I stretch, coupled with some bending motions.

     

Direct vs Indirect Grafting of Alkyl and Aryl Halides

The direct and indirect electrochemical grafting of alkyl and aryl halides (RX, ArX) on carbon, metal and polymer surfaces is examined. Their electrochemical reduction occurs at highly negative potential in organic solvents and very often produces carbanions because the reduction potentials of RX and ArX are more negative than those of their corresponding radicals. Therefore, direct electrografting of alkyl and aryl radicals generated from RX and ArX is not easy to perform. This obstacle is overcome using aryl radicals derived from the 2,6-dimethylbenzenediazonium salt (2,6-DMBD), which do not react on the electrode surface due to their steric hindrance but react in solution by abstracting an iodine or bromine atom from RX (X=I, Br) or ArI to give alkyl or aryl radicals. As a consequence, alkyl and aryl radicals are generated at very low driving force by diverting the reactivity of aryl radicals derived from an aryl diazonium salt; they attack the electrode surface and form strongly attached organic layers. This strategy applies to the chemical modification of polymers (polyethylene, polymethylmethacrylate) by alkyl halides under heating.     

A simple synthesis of geiparvarin

A simple, efficient (nine steps, 22% overall yield) synthesis of geiparvarin is described.     

Practical and efficient synthesis of perfluoroalkyl iodides from perfluoroalkyl chlorides via modified sulfinatodehalogenation

A novel two-step one pot synthesis of perfluoroalkyl iodides (α,ω-diiodoperfluoroalkanes) from perfluoroalkyl chlorides (α-chloro-ω-iodoperfluoroalkanes) has been developed by initial conversion to the corresponding sodium perfluoroalkanesulfinates with sodium dithionite and then subsequent oxidation by iodine.     

A simple stereocontrolled synthesis of salinosporamide A

A simple and effective stereocontrolled synthesis of salinosporamide A has been developed. This process, the first synthesis of salinosporamide A, is capable of providing the compound in substantial quantities for further biological studies. Salinosporamide A was of special interest as a synthetic target because of its potent in vitro cytotoxic activity against many tumor cell lines (IC(50) values of 10 nM or less).     

A simple synthesis of γ-aminoacids

The addition of dianions of carboxylic acids to bromoacetonitrile, leads, in good yields, to the corresponding γ-cyanoacids that give γ-aminoacids on hydrogenation. This two-step methodology improves the results previously described.     

A new reagent for the efficient synthesis of disulfides from alkyl halides

Benzyltriethylammonium tetracosathioheptamolybdate [(C₆H₅CH₂N(Et)₃)₆Mo₇S₂₄] has been found to be a superior sulfur transfer reagent for the conversion of alkyl halides to the corresponding disulfides in excellent yields under very mild reaction conditions.     

A simple synthesis of 2-thiohydantoins

2-Thiohydantoin derivatives are produced by heating a mixture of thiourea and an alpha-amino acid. The method described offers the advantages of simplicity, low cost, easy work-up and scalability.