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.     

Determination of gallium in biological materials by electrothermal atomic absorption spectrometry

In this determination of gallium, the condition of the graphite tubes influences the peak height. Common acids and salts seriously affect the results, but in the presence of EDTA, interferences of nitric and hydrochloric acids are suppressed completely, and interferences of phosphoric acid and some salts are suppressed partly. To compensate for the effects, a standard addition procedure is proposed, and is applied to healthy and tumor.bearing mice. A linear calibration is obtained for 0.12–12 ng Ga in 50-μl aliquots. The method is applied to tissues and body fluids with good recovery and precision.     

Cluster Formation of 1-Butanol–Water Mixture Leading to Phase Separation

Microscopic structures of 1-butanol (1-BuOH)–water mixtures in the presence and absence of salts are studied through the mass spectrometric analysis of clusters generated from the fragmentation of liquid droplets. The analysis of cluster structures provides information on the phase separation of 1-BuOH–water mixtures from the microscopic viewpoint. In a saturated solution of 1-BuOH in water, 1-BuOH exists as hydrated 1-BuOH clusters and self-associated 1-BuOH clusters. With further addition of 1-BuOH, a 1-BuOH rich phase is generated. When the salt (LiCl, NaCl, MgCl₂, etc.) coexists in the 1-BuOH–water mixtures, the cation is preferentially solvated by the 1-BuOH to form M ⁺(1-BuOH) _m or M ²⁺(1-BuOH) _m clusters: M ⁺ = Li⁺, Na⁺, Mg²⁺ = Mg²⁺, etc., m = 1, 2, 3, ... Since the formation of M ⁺(1-BuOH) _m corresponds to an increase of the self-associated 1-BuOH clusters in water, the presence of the salt induces the phase separation at lower 1-BuOH concentrations.     

A novel dry route to ortho-functionalized triarylbismuthanes that are difficult to access by conventional wet routes

When an aryl iodide bearing an electron-withdrawing group at the ortho position was milled together with bismuth shots and calcite grains in the presence of Cu powder and CuI using a laboratory ball mill, the corresponding ortho-functionalized triarylbismuthane was obtained in moderate to good yield.     

A novel fluorescent probe for zinc ion based on boron dipyrromethene (BODIPY) chromophore

ZnAB has the combined structure of N,N-bis(2-pyridylmethyl)ethylenediamine as a specific chelater for Zn(2+) and 1,3,5,7-tetramethyl-8-phenyl-boron dipyrromethene as a fluorophore. Complexation of ZnAB with Zn(2+) produces a remarkable enhancement of fluorescence intensity. ZnAB has the advantages of less sensitivity to solvent polarity and pH than fluorescein-based Zn(2+) probes. Furthermore, it is not influenced by other cations, such as Na(+), K(+), Ca(2+), and Mg(2+), which exist at high concentrations under physiological conditions, even at 2.5 mM. The results show that ZnAB is a Zn(2+) probe suitable for biological applications.     

Synthesis of polyoxyethylene grafting nylon 6 and the selective separation of cyclohexane/cyclohexanone/cyclohexanol mixture through its membranes

A polymer membrane having polyoxyethylene grafting nylon 6 was prepared by reacting of nylon 6 and ethylene oxide. The chemical compositions of the polyoxyethylene grafting nylon 6 were determined by ¹H NMR. Degree of substitution for amide group, x, and degree of polymerization for polyoxyethylene, n, in bulk polymerization at 80°C for 4–9.5 h were evaluated: x = 0.32 ± 0.01–0.56 ± 0.02 and n = 2.8 ± 0.1–6.0 ± 0.3. The polyoxyethylene grafting nylon 6 membrane showed a selective separation of cyclohexanol from a cyclohexane/cyclohexanone/cyclohexanol mixture by a pervaporation technique. The FTIR and flux analyses verified that the selectivity for cyclohexanol was attributed to the hydrogen-bonding interaction between hydroxyl group in cyclohexanol and the hydroxyl group in polyoxyethylene grafting chain. The pervaporation and an adsorption experiment of cyclohexanol through the present membrane showed that hydroxyl group in graft chain acted as a carrier for cyclohexanol.     

Total synthesis of an antitumor antibiotic,Fostriecin (CI-920)

The total synthesis of an antitumor antibiotic, fostriecin (CI-920), via a highly convergent route is described. A characteristic feature of the present total synthesis is that the synthesis was achieved via a coupling procedure of three segments A, B, and C. The unsaturated lactone moiety of fostriecin, corresponding to segment A, was constructed from a known Horner-Emmons reagent, and the stereochemistry of the C-5 position was introduced by asymmetric reduction with (R)-BINAl-H. Segment B having a series of stereogenic centers was synthesized from (R)-malic acid and the stereogenic centers at the C-8 and C-9 positions were prepared by a combination of Wittig reaction and Sharpless asymmetric dihydroxylation reaction. The conjugated Z,Z,E-triene moiety of fostriecin, corresponding to segment C, was eventually constructed by Wittig reaction and Stille coupling reaction. The phosphate moiety, which is known to be essentially important for the antitumor activity, was introduced via two routes: (i) direct phosphorylation of the monohydroxyl derivative in which other hydroxyl groups are protected with silyl groups; (ii) cyclic phosphorylation and selective cleavage of the cyclic phosphate derivative. Although the former route is basically the same as those reported by other groups, the latter route is novel and more effective than the former one. The present total synthesis would serve as a versatile synthetic route to not only fostriecin, but also its various analogues including stereoisomers.     

Assembly of an Axially Chiral Dynamic Redox System with a Perfluorobiphenyl Skeleton into Dumbbell‐ or Tripod‐type Electron Donors

The incorporation of F atoms endows a diethenylbiphenyl‐based electron donor with configurational stability and S_NAr reactivity. The former enables the dynamic redox pair of (R_ax)‐ 1 /(R_ax,R,R)‐ 1 ²⁺ to exhibit drastic UV/Vis and CD spectral changes upon electrolysis, whereas the latter makes it possible for (R_ax)‐ 1 to serve as a useful chiral synthon for the production of larger assemblies [(R_ax,R_ax)‐ 2 d,p,m and (R_ax,R_ax,R_ax)‐ 3 ] containing two or three dyrex units. These dyads and triad also exhibit a clean electrochiroptical response with isosbestic points owing to one‐wave multi‐electron transfer.