The beta-decay energies of103In and104In

The β⁺ spectra of neutron-deficient nuclei with mass numbers 103 and 104 have been measured, using a semiconductor beta spectrometer. The nuclei were produced by on-line mass separation of reaction products formed by bombarding an enriched Mo target with Ne ions. Values for Q_EC have been deduced. The decay energies are in agreement with systematics. The decay of¹⁰⁴In shows remarkably strong feeding to levels above 5 MeV. In addition, Q_EC values for₁₀₃Cd,₁₀₃Ag,₁₀₄Ag and_104mAg have been determined.     

Radiopharmaceutical preparation of L-6-[123I]-iodo-m-tyrosine a potential SPECT brain imaging agent

A method for radiopharmaceutical preparation of L-6-[¹²³I]-iodo-m-tyrosine a potential SPECT brain imaging agent is described. The method is based on direct electrophilic radioiodination of L-m-tyrosine with [¹²³I] NaI/chloramine-T (CAT) and small amount of KI as a carrier at pH 1.0 where L-6-[¹²³I]-iodo-m-tyrosine is the predominant isomer. A high radiochemical yield of L-6-[¹²³I]-iodo-m-tyrosine up to 70% has been achieved by adding small amount of KI (0.001 g) as a carrier to the reaction mixture. The pure 6-isomer was separated by reverse phase radio high pressure liquid chromatography (HPLC) on RP-18 column using 0.02M sodium acetate/ethanol (9010) adjusted to pH 3.9 with glacial acetic acid at a flow rate 2 ml/min. According to the signals of the UV detector (=254) the 6-isomer was eluted at a retention time 12.5 minutes,K=6. The eluted fraction of L-6-[¹²³I]-m-tyrosine pooled together, evaporated under reduced pressure, then dissolved in 5 ml isotonic phosphate buffer and sterilized by passing through 0.22 m millipore filter. The sterile solution was now ready for nuclear medical applications. The biological distribution of L-6-[¹²³I]-iodo-m-tyrosine in mice was studied. The results showed that 3% of the injected dose is taken up in dopamine rich striatum 30 minutes after injection and not in norepinephrine-rich hypothalamus.     

Synthesis of a nonpolar,chemically bonded stationary phase with low residual hydroxyl group content

Summary A microporous silica support, LiChrosorb Si-100, has been silanized with octyldimethylchlorosilane and octylmethyldichlorosilane. The repeatability of the silanization procedure was within about 2%. In general, these nonpolar modified silicas still contain too many residual hydroxyl groups, causing bifunctional behaviour of the adsorbent. A partial condensation of surface silanol groups at a drying temperature >200°C, prior to the chemical modification, decreases the residual hydroxyl group content. With respect to this residual polarity, monochlorosilanes appear to be effective. The concentration of bonded octyl chains remains virtually constant up to a drying temperature of 400°C. Owing to silanization, the specific surface decreases by 15–20%, whereas the pore volume decreases by 25%.     

A comparative study on the separation of radiozirconium via ion-exchange and solvent extraction techniques, with particular reference to the production of 88Zr and 89Zr in proton induced reactions on yttrium

The radiochemical separation of no-carrier-added zirconium from proton irradiated yttrium was studied by two techniques, namely, ion-exchange chromatography using Dowex 50W-X8 and Dowex 21K resins, and solvent extraction using HDEHP and TPPO, the latter reagent being employed for the first time for separation of radiozirconium from bulk of yttrium. Out of all those techniques, the solvent extraction using TPPO was found to be the best: the separation yield of radiozirconium was >97%, the time of separation was short, the contamination from the long-lived ⁸⁸Y activity was low (10⁻⁴%) and the final product was obtained in the form of oxalate. The production of ⁸⁹Zr and ⁸⁸Zr of high radionuclidic and chemical purity via irradiation of yttrium targets with protons of energies 12 and 20 MeV, respectively, is described. The experimental yields of the two radionuclides were found to be 28 MBq/μA·h and 1.63 MBq/μA·h, respectively. Each value corresponds to about 80% of the respective theoretical yield.     

联苯胺分光光度法测定食盐中碘含量

基于在盐酸介质中,碘酸钾氧化联苯胺使其显色,提出了光度法测定食盐中微量碘的方法。在40℃的水浴中,当2 mol.L-1盐酸溶液用量为1.00 mL0、.42 g.L-1联苯胺溶液用量为0.80 mL时,方法的线性范围为100~1 400μg.L-1,最大吸收波长在425 nm处,表观摩尔吸光率为1.4×105L.mol-1.cm-1。用于测定加碘食盐中碘含量的测定,回收率在97.5%~101.2%之间,相对标准偏差(n=7)在0.9%~1.9%之间。     

Pectin, a versatile polysaccharide present in plant cell walls

Pectin or pectic substances are collective names for a group of closely associated polysaccharides present in plant cell walls where they contribute to complex physiological processes like cell growth and cell differentiation and so determine the integrity and rigidity of plant tissue. They also play an important role in the defence mechanisms against plant pathogens and wounding. As constituents of plant cell walls and due to their anionic nature, pectic polysaccharides are considered to be involved in the regulation of ion transport, the porosity of the walls and in this way in the control of the permeability of the walls for enzymes. They also determine the water holding capacity. The amount and composition of pectic molecules in fruits and vegetables and other plant produce strongly determine quality parameters of fresh and processed food products. Pectin is also extracted from suitable agro-by-products like citrus peel and apple pomace and used in the food industry as natural ingredients for their gelling, thickening, and stabilizing properties. Some pectins gain more and more interest for their health modulating activities. Endogenous as well as exogenous enzymes play an important role in determining the pectic structures present in plant tissue, food products, or ingredients at a given time. In this paper functional and structural characteristics of pectin are described with special emphasis on the structural elements making up the pectin molecule, their interconnections and present models which envisage the accommodation of all structural elements in a macromolecule. Attention is also given to analytical methods to study the pectin structure including the use of enzymes as analytical tools.     

Convenient preparation of (4-iodophenyl)aryliodonium salts

The (4-iodophenyl)aryliodonium salts bis(4-iodophenyl)iodonium, (4-iodophenyl)(4-methoxy-phenyl)iodonium and (4-iodophenyl)(2-thienyl)iodonium, each with three different anions, were prepared using 4-iodo-1-[hydroxy(tosyloxy)iodo]benzene. These are suitable precursor molecules for electrophilic radiofluorination and other 4-iodophenylation reactions, whose products can subsequently serve as reagents for transition metal catalysed cross coupling and other metal organic reactions.     

Extremely strong self-assembly of a bimetallic salen complex visualized at the single-molecule level

A bis-Zn(salphen) structure shows extremely strong self-assembly both in solution as well as at the solid-liquid interface as evidenced by scanning tunneling microscopy, competitive UV-vis and fluorescence titrations, dynamic light scattering, and transmission electron microscopy. Density functional theory analysis on the Zn(2) complex rationalizes the very high stability of the self-assembled structures provoked by unusual oligomeric (Zn-O)(n) coordination motifs within the assembly. This coordination mode is strikingly different when compared with mononuclear Zn(salphen) analogues that form dimeric structures having a typical Zn(2)O(2) central unit. The high stability of the multinuclear structure therefore holds great promise for the development of stable self-assembled monolayers with potential for new opto-electronic materials.