血清必需元素测定中样品预处理方法的探讨

对血清必需元素测定的样品预处理方法进行了研究，用火焰原子吸收法测定了经不同处理的血清样品中的锌，铜，铁，钙，镁含量，结果显示，预处理方法不同，其测定结果有较大差异，变异系数，镁为７．９４％，锌，铜，铁，钙在１５．１９％～５３．５３％之间，并对各样品作了精密度和准确度实验。     

The Reaction of 4-Formylsydnone with Nitroalkanes

Under various basic solutions and reaction durations, 3-substituted 4-formyIsydnones and nitroalkanes containing α-active hydrogen (e.g. nitromethane and nitroethane) are converted to β-nitroalcohols, nitroalkenes and dinitroalkanes. β-Nitroalcohols are obtained only by electrochemical reaction on an electrogenerated base (EGB). The mechanism of overall reaction steps in particular is discussed.     

Conformations of luteoskyrin and rugulosin in solution

The pigments Luteoskyrin (Ls) and Rugulosin (Rg) might adopt a priori two extreme conformations, a planar and an angular one. To determine the predominant conformation in solution, the nature of the lowest energy transition of the chromophores and the presence of intramolecular H-bonding have been investigated. The solvent effects on electronic absorption and CD spectra indicated the π-π* nature of the lowest energy transition. Treatments of the electronic absorption results according to McRae and Kosower relations, IR absorption and PMR spectra suggested the presence of strong intra-molecular H-bonds. From these results it was concluded that Ls and Rg adopted in a variety of solvents the most planar conformation.     

Dimeric iron n-confused porphyrin complexes

A dimeric iron N-confused porphyrin, [Fe(NCTPP)]2 was obtained from the anaerobic reaction of Fe(NCTPP)Br with NaSePh while under aerobic conditions a hydroxo bridged iron dimer with Na bridging the outer-N atoms was obtained and oxygenation occurred on the inner core pyrrolic carbon to form a novel ONCTPP porphyrinic ring.     

Investigation of oligomethylmethacrylate-lithium and its donor-acceptor complexes with organometal compounds by means of infrared spectroscopy

Anionic polymerization of methyl methacrylate in THF and toluene at ?70° was studied by means of i.r. spectroscopy. The reaction mixtures show characteristic absorption at 1600–1750 cm^?1 caused by the stretching vibrations of the propagating centre as well as by the groups obtained in side reactions (metal splitting, addition to a carbonyl group, cyclization). Sec-butyllithium is more effective in THF than n-butyllithium, ethyllithium and fluorenyllithium. When polymerizing in toluene, small amounts of a donor (THF or HMPT) cause formation of active centres similar to those in pure THF. The “living” ends of oligo-MMA form 1:1 complexes with electron acceptors such as trialkylaluminium and triethylboron.     

Investigations into the synthesis of 6-ethyl-5-(4-pyridinyl)-2,4-pyrimidinediamine as a potential antimalarial agent

The synthesis of 6-ethyl-5-(4-pyridinyl)-2,4-pyrimidinediamine ( 2 ), the pyridine analog of pyrimethamine, is described. Condensation of 4-pyridineacetonitrile ( 3 ) with methyl propionate afforded α-(1-oxopropyl)-4-pyridineacetonitrile ( 4 ). Treatment with triethyl orthopropionate gave primarily the undesired N-alkylated material. However reaction of the crude mixture with guanidine afforded 2 in low yield. This material was devoid of significant antimalarial activity.     

Chemical activation of carbon nanofibers and nanotubes

Method of thermodynamic simulation was used to calculate the equilibrium parameters of reactions of graphite with anhydrous LiOH, NaOH, and KOH and with the alkalis in the presence of water vapor. The change in the specific surface area and mass loss were used to analyze the interaction of carbon nanofibers and multilayer carbon nanotubes produced by catalytic pyrolysis of CH₄ with the alkalis.     

Separation of peptides and proteins by capillary electrophoresis using acidic buffers containing tetraalkylammonium cations and cyclodextrins

A method for improving separations of peptides and other positively charged species in capillary zone electrophoresis with untreated capillaries using acidic buffers containing tetraalkylammonium cations is described. Tetramethylammonium and tetrabutylammonium cations dynamically modify the capillary surface, leading to a reversal in the direction of the electroosmotic flow. As a result, the adsorption of positively charged peptides and proteins is minimized, and resolution and peak capacity are improved as the migration of cationic analytes is counterbalanced by the electroosmotic flow. The combining effect of reversing electroosmotic flow and cyclodextrin inclusion complexation on separations of closely related peptides and a protein mixture, as well as tryptic digest of hemoglobin is demonstrated.     

Natural anti-HIV agents. Part 3: Litseaverticillols A-H, novel sesquiterpenes from Litsea verticillata

Bioassay directed-fractionation led to the identification of litseaverticillols A-H (1-8) from the leaves and twigs of Litsea verticillata Hance. These new sesquiterpenes possess a unique skeleton that was recently designated as ‘litseane’. The structures of these compounds were determined by spectroscopic means including 1D and 2D NMR data. Structural configurations were determined by ROESY experiments. Mosher ester reactions and optical rotation measurements established the sesquiterpenes 1-8 as racemates. Isolates 1-8 inhibited HIV-1 replication in HOG.R5 cells with IC₅₀ values ranging from 2 to 15 μg/ml (8-58 μM) while affecting the growth of HOG.R5 at concentrations 2-3-fold higher. Based on this data, structure-activity relationships can be discerned, suggesting compounds of this class are good candidates for analog production.     

Tasumatrols P – T,Five New Taxoids from Taxus sumatrana

The phytochemical investigation of the more polar fractions from the leaves and twigs of Taxus sumatrana (Taxaceae) afforded five new taxane diterpene esters, tasumatrols P–T ( 1 – 5 ) possessing an 11(15→1),11(10→9)‐diabeotaxane skeleton. Compounds 1, 4 , and 5 contain an α‐hydroxy group at C(14), while 3 has no OH group at either C(13) or C(14). Compound 2 is a natural 4,5‐acetonide derivative, while 4 has an unusual spiro‐connected 2‐hydroxy‐2‐phenyl‐1,3‐dioxolane ring. Ten known taxoids, were also isolated in the course of the chromatographic fractionation. Five additional new O‐acetyl derivatives 3a, 4a, 4b, 5a , and 5b were prepared from the taxanes 3 – 5 . The structures of all new compounds were established on the basis of their spectroscopic analyses. Compound 1 showed mild cytotoxic activity against human Hela and Daoy tumor cells.