Improvement of the Golgi Method by pH Control

Experiments were made to test the influence of the pH of the fixing fluid (ranging from 1.0-8.1) and that of the chromating fluid (1.65-7.8) on subsequent silver impregnation. Brains of adult monkeys, cats, dogs, rabbits, guinea pigs, rats and mice were fixed by the pulsating-perfusion method of Haushalter and Bertram (1955), after first washing out the blood with saline-acacia solution of the same pH as that of the 10% formol-saline-acacia used for fixation. The brains were sliced to 3 mm thickness and the slices further fixed 1-2 days in 10% formalin with its pH adjusted to that of the preceding fixing fluid. Chromation for 1 day followed, with acidified ZnCrO₄ at pH 1.65-5.9 and buffered Na₂CrO₄ at pH 7.8. Silvering for 2 days in 0.75% AgNO₃ solution effected the staining. Dehydration, paraffin embedding and sectioning completed the process.

From these experiments, it was found that fixation at pH 7.0-7.2 followed by chromation at pH 3.1 in a mixture of ZnCrO₄, 60 gm and formic acid, 35 ml, diluted to 1000 ml with distilled water, was optimum for best impregnation of nerve cells and their processes. Human brain and that of newborn mammals, although not perfused, responded well to the controlled-pH procedure. The advantages of the technic are the staining of nerve cells in regions refractory to previous methods and the relatively short time needed for its completion.     

A Silver Impregnation Method for Nervous Tissue Suitable for Routine use with Mounted Sections

A simple, reliable silver impregnation method for nervous tissue is described for tissues fixed in various fixatives including formalin, Bouin, and Sum. Sections are impregnated in a solution containing 1 g Protargol, 2 ml of a 1% Cu(NO₃)₂ solution, 2 ml of a 1% AgNO₃ solution, and 2-4 drops 30% H₂O₂ in 100 ml distilled water. Sections are impregnated 4-5 days at 37 C and thereafter reduced in a hydroquinone-formalin solution. This is followed by gold toning and subsequent reduction, dehydration and mounting. This method has been found to be very reliable and selective.     

A Rapid Silver Impregnation Method for Nervous Tissue: A Modified Protargol-Peroxide Technic

A rapid, reliable silver impregnation method is described for nervous tissue fixed in formol-saline, Bouin or Sum. Sections are impregnated for 10-15 minutes at room temperature or 37 C in a solution containing 0.5 g Protargol-S, 0.005-0.01 g allantoin, 1 ml of 1% Cu[NO₂]₂, 1 ml of 1% AgNO₃. and 1-2 drops of 30% H₂O₂ in 100 ml distilled water. Thereafter the dons arc reduced in a hydroquinone-formalin solution. This is followed by gold toning and subsequent reduction and mounting. Alternatively. following the first reduction, the silver image can be intensified by placing sections in a silver-allantoin bath which is followed by reduction and mounting. This method is very reliable and selective, making it suitable for general routine and research use.     

Monomeric and dimeric mixed-ligand copper(II) complexes of 2,2′-bipyridine/1,10-phenanthroline and 1-methylimidazole with imidazoles as catalysts for superoxide dismutation

Monomeric complexes [Cu(LL)(L′)(NO₃)₂] (where LL is 2,2′-bipyridine or 1,10-phenanthroline and L′ is 1-methylimidazole) and dimeric complexes [Cu₂(LL)₂(L″)]NO₃ (where L″ is an anion of imidazole or 2-methylimidazole) have been synthesized. These complexes show a d-d transition in the range of 600 to 710 nm. The infrared spectra of monomeric complexes show that the NO₃⁻ is coordinated to copper as a monodentate ligand through an oxygen atom. The ESR spectra of monomeric complexes indicate that the ligands are bonded in axial environment around copper (square pyramidal geometry) with three nitrogen donors occupying an equatorial plane. The ESR spectra of dimeric complexes show a broad signal at about G = 2 with an additional weak signal at about G = 4. This suggests that two copper atoms are in close proximity of < 7 Å. The ESR studies reveal that the formation of imidazolate-bridged binuclear copper(II) complexes from [Cu(LL)(L′)(NO₃)₂] and imidazole is pH dependent with apparent pK_a values of 8.25 to 8.30. The superoxide dismutase activity of ICu(phen)(L′)(NO₃)₂], [Cu(bipy)(L′)(NO₃)₂], and [Cu₂(bipy)₂(L′)₂(L″)]NO₃ has been measured and the latter two complexes show better activity than the former complex.     

The stereochemistry of Co(III)-amine complexes. The use of nOe and COSY H NMR spectroscopy to determine structure in solution

It is shown how 1D nOe and 2D COSY ¹H NMR spectroscopy can be used to assign the stereochemistry of Co(III) amine complexes. By using d₆-DMSO as solvent together with a small quantity of DCl all non-equivalent N---H hydrogens can be distinguished at 300 MHz. Through-space (nOe), and through-bond (COSY), associations with other N---H and C---H hydrogens can then be determined. This leads to a complete assignment of structure in solution. The technique is applied to the complexes syn(N), anti(N)-[Co(cyclen) (NH₃)₂] (ClO₄)₃, syn(N), anti(Cl)-[Co(cyclen) (NH₃)Cl] (ClO₄)₂, anti(N), syn(Cl)-[Co(cyclen) (NH₃)Cl](ClO₄)₂, syn(N), anti(O)-[Co(Mecyclen)-(GlyO)](ClO₄)₂ and Δ-cis-[Co(δ-en)₂(NO₂)₂](NO₂).     

Syntheses, structures and magnetic properties of mono- and di-manganese inclusion compounds

Mono- and di-manganese inclusion compounds 1 and 2 are reported. Two mono-manganese molecules Mn(bpy)₂(NO₃)₂ (bpy=2,2′-bipyridine) and [Mn(bpy)₂(NO₃)(H₂O)]·NO₃ coexist in the mole ratio of 1:1 in the structure of 1, while two di-manganese molecules [Mn₂O(bpy)₂(phtha)₂(H₂O)₂]·(NO₃)₂ (phtha=phthalate) and [Mn₂O(bpy)₂(phtha)₂(NO₃)(H₂O)]·NO₃ in the structure of 2. Refluxing Mn(NO₃)₂/bpy/phthalic acid reaction mixtures in CH₃CN leads to the isolation of 1, further concentration of the reaction solution in raising temperature results in 2. The Mn₁ and Mn₂ units in the inclusion compounds 1 and 2 are similar to other reported Mn₁ and Mn₂ analogs, respectively. The Jahn–Teller distortion was observed to give rise to the elongation along the O_terminal---Mn---O_carboxyl axes for all the four Mn(III) sites in 2, leading to unexpected longer Mn(III)---O_aqua than Mn(II)---O_aqua in 1. Extensive hydrogen bonding interactions among H₂O, NO₃ ⁻ and COOH were observed in the two inclusion compounds. Cyclic voltammetry of 2 in DMF displays two quasi-reversible redox couples at +0.10/+0.22 and −0.43/−0.36 V assigned to the Mn(III)Mn(IV)/2Mn(III) and 2Mn(III)/Mn(III)Mn(II), respectively. Variable temperature magnetic susceptibilities of 1 and 2 were measured. The data were fit to a model including axial zero-field splitting term and a good fit was found with D=1.77 cm⁻¹, g=1.98 and F=1.48×10⁻⁵ for 1. For 2, the least-squares fitting of the experimental data led to J=2.37 cm⁻¹, g=2.02 and D=0.75 cm⁻¹ with R=1.45×10⁻³.     

Mixed anion lanthanide(III) crown ether complexes: crystal structures of [LaCl2(NO3)(12-crown-4)]2, [La(NO3)(OH2)4-(12-crown-4)]Cl2·CH3CN and [LaCl2(NO3)(18-crown-6)]

Reaction of LaCl₃·7H₂O containing small amounts of La(NO₃)₃·7H₂O as an impurity with 12-crown-4 or 18-crown-6 in 3:1 CH₃CN:CH₃OH resulted in the isolation of the mixed anion complexes [LaCl₂(NO₃)(12-crown-4)]₂, [La(NO₃)(OH₂)₄(12-crown-4)]Cl₂·CH₃CN and [LaCl₂(NO₃)(18-crown-6)]. The nine-coordinate dimer, [LaCl₂(NO₃)(12-crown-4)]₂, has all of the anions in the inner coordination sphere and La³⁺ has a capped square antiprismatic geometry. It crystallizes in the orthorhombic space group Pbca with (at −150 °C) a = 12.938(6), B = 15.704(3), C = 13.962(2) Å, and D_calc = 2.08 g cm⁻³ for Z = 4. The second complex isolated from the same reaction, [La(NO₃)(OH₂)₄(12-crown-4)]Cl₂·CH₃CN, has the bidentate nitrate anion in the inner coordination sphere but the two chloride anions are in a hydrogen bonded outer sphere. This complex is ten-coordinate 4A,6B-expanded dodecahedral and crystallizes in the monoclinic space group P2₁ with (at 20 °C) A = 7.651(2), B = 11.704(7), C = 11.608(4) Å, β = 95.11(2)°, and D_calc = 1.80 g cm⁻³ for Z = 2. The 18-crown-6 complex, [LaCl₂(NO₃)(18-crown-6)], has all inner sphere anions and has ten-coordinate 4A,6B-expanded dodecahedral La³⁺ centers. It crystallizes in the orthorhombic space group Pbca with (at 20 °C) a = 14.122(7), B = 13.563(5), C = 19.311(9) Å, and D_calc = 1.89 g cm⁻³ for Z = 8.     

外源γ-氨基丁酸对Ca(NO3)2胁迫下甜瓜幼苗NO3--N同化的影响

以盐敏感型甜瓜品种‘一品天下208’为试材,用80 mmol·L^-1 Ca(NO₃)₂模拟设施土壤盐渍化,采用深液流水培,研究外源 γ-氨基丁酸(GABA)对Ca(NO₃)₂胁迫下甜瓜幼苗硝态氮(NO₃^--N)同化的影响.结果表明: Ca(NO₃)₂胁迫显著降低了甜瓜幼苗体内硝酸还原酶(NR)、谷氨酰胺合酶(GS)和谷氨酸合酶(GOGAT)活性,增强了谷氨酸脱氢酶(GDH)、谷草转氨酶(GOT)和谷丙转氨酶(GPT)活性,导致铵态氮(NH₄⁺-N)和游离氨基酸含量增加,NO₃^--N和可溶性蛋白质含量下降,植株生长和光合作用受到严重抑制.Ca(NO₃)₂胁迫下,外源喷施GABA有效促进了甜瓜根系对NO₃^--N的吸收及其向地上部的转运,并通过增强NR、GS和GOGAT活性提高了甜瓜幼苗对NH₄⁺的同化力;通过抑制GDH脱氨作用减少了甜瓜幼苗体内NH₄⁺的释放量,从而缓解了盐诱导产生的NH₄⁺-N积累所造成的氨毒害作用;外源喷施GABA也能调节甜瓜组织中氨基酸代谢途径,促进蛋白质的合成.表明外源GABA能增强甜瓜幼苗对NO₃^--N的同化能力,调控氨基酸代谢,进而有效缓解Ca(NO₃)₂胁迫对甜瓜幼苗的盐伤害作用.     

外源γ-氨基丁酸对Ca(NO3)2胁迫下甜瓜幼苗NO3——N同化的影响

以盐敏感型甜瓜品种‘一品天下208’为试材,用80 mmol·L^-1 Ca(NO₃)₂模拟设施土壤盐渍化,采用深液流水培,研究外源 γ-氨基丁酸(GABA)对Ca(NO₃)₂胁迫下甜瓜幼苗硝态氮(NO₃^--N)同化的影响.结果表明: Ca(NO₃)₂胁迫显著降低了甜瓜幼苗体内硝酸还原酶(NR)、谷氨酰胺合酶(GS)和谷氨酸合酶(GOGAT)活性,增强了谷氨酸脱氢酶(GDH)、谷草转氨酶(GOT)和谷丙转氨酶(GPT)活性,导致铵态氮(NH₄⁺-N)和游离氨基酸含量增加,NO₃^--N和可溶性蛋白质含量下降,植株生长和光合作用受到严重抑制.Ca(NO₃)₂胁迫下,外源喷施GABA有效促进了甜瓜根系对NO₃^--N的吸收及其向地上部的转运,并通过增强NR、GS和GOGAT活性提高了甜瓜幼苗对NH₄⁺的同化力;通过抑制GDH脱氨作用减少了甜瓜幼苗体内NH₄⁺的释放量,从而缓解了盐诱导产生的NH₄⁺-N积累所造成的氨毒害作用;外源喷施GABA也能调节甜瓜组织中氨基酸代谢途径,促进蛋白质的合成.表明外源GABA能增强甜瓜幼苗对NO₃^--N的同化能力,调控氨基酸代谢,进而有效缓解Ca(NO₃)₂胁迫对甜瓜幼苗的盐伤害作用.     

Synthesis and characterization of polypyridineruthenium(II) complexes containing a linear ambidentate ligand, NCO or NCS, and reaction of isocyanato complexes under acidic conditions

Isocyanato and isothiocyanatopolypyridineruthenium complexes, [Ru(NCX)Y(bpy)(py)₂]ⁿ⁺ (bpy=2,2′-bipyridine, PY=pyridine; X=O, Y=NO₂ for n=0, and Y=py for n=1; X=S, Y=NO₂ for n=0, Y=NO for n=2, and Y=py for n=1), were synthesized by the reaction of polypyridineruthenium complexes with potassium cyanate or sodium thiocyanate salt. Isocyanatoruthenium(II) complexes, [Ru(NCO)(NO₂)(bpy)(py)₂] and [Ru(NCO)(bpy)(py)₃]⁺, react under acidic conditions to form the corresponding ammineruthenium complexes, [Ru(NO)(NH₃)(bpy)(py)₂]³⁺. The molecular structures of [Ru(NCO)(bpy)(py)₃]ClO₄, [Ru(NCS)(NO)(bpy)(py)₂](PF₆)₂ and [Ru(NO)(NH₃)(bpy)(py)₂](PF₆)₃ were determined by X-ray crystallography.     

Carbomethoxylation of propylene catalyzed by sulfonated resin-supported cationic palladium catalysts

The cationic palladium complex, [Pd(CH₃CN)(PPh₃)₃](BF₄)₂, has been supported onto sulfonated resins. The carbomethoxylation of propylene catalyzed by sulfonated resin-supported cationic palladium catalyst precursors has been carried out at temperatures of 100 160 °C and at pressures of 1500 2000 psi. The supported cationic Pd²⁺ complex precursors have higher catalytic activity than the supported Pd(NO₃)₂ and Pd(PPh₃)₄ catalyst precursors.     

Second-sphere coordination of ‘star’-shaped hexakis(N-pyridin-4-one)benzene (HPOB) with hexakis(methanol)nickel(II) nitrate; unusual (NO3)(HPOB)(NO3) π-stacked ‘sandwiching’

It is shown by X-ray studies that the compound Ni(HPOB)(NO₃)₂(MeOH)₉ [where HPOB=hexaxis(N-pyridin-4-one)benzene] contains [Ni(MeOH)₆]²⁺ cations hydrogen-bonded to the oxygen atoms of the pyridone units in HPOB, with the resulting six-connectivity at both metal and HPOB producing a three-dimensional network array essentially topologically equivalent to the -Po structure. The pyridone rings in the HPOB molecules are arranged orthogonally to the central C₆ ring and the nitrate anions form an unusual (NO₃ ⁻)(HPOB)(NO₃ ⁻) ‘sandwich’ by a combination of π-stacking and C---HO hydrogen bonds.     

Metachromatic Reaction of Pancreatic B Cells to Toluidine Blue; Influence of pH on Staining

The granules of islet B cells show an intense β metachromasia when paraffin sections of pancreas fixed in Bouin's fluid or formalin are dipped for 1 min in a 0.1% aqueous solution of toluidine blue O₂ buffered to pH 6.0 with acetate or phosphate. This reaction provides a quick method for surveying the condition of B cells in experimental work. A weak staining is observable at pH 4.5 and becomes distinct at pH 5.5-6.0. Oxidation of sections (0.25% KMnO₄ in 0.5% H₂SO₄, for 1 min, recommended) prior to staining intensifies the metachomatic reaction conspicuously. The metachromatic substance could not be demonstrated after fixation in either ethanol or acetone. It corresponds to the aldehyde fuchsin-positive and pseudoisocyanin-metachromatic substance in its occurrence and distribution in the B cells, as shown by different physiological states of various animals, including fasted and glucose-administered guinea pigs. It is thought to be topographically coincident but not necessarily identical to insulin.     

胞外三磷酸腺苷对铅胁迫下植物细胞损伤和过氧化氢及其清除酶水平的调节

细胞外三磷酸腺苷（extracellular adenosine-5'-triphosphate）是植物细胞的重要信号分子。以烟草悬浮细胞BY-2（Nicotiana tabacum L.cv.Bright Yellow-2）为材料,探讨了胞外三磷酸腺苷对铅胁迫下细胞损伤、H₂O₂（过氧化氢）含量及H₂O₂清除酶活性的影响。结果显示,随着Pb（NO₃）₂浓度的不断提高（30~400 μmol·L^-1）,细胞外三磷酸腺苷含量呈现出逐渐下降的趋势,但胞内三磷酸腺苷含量及细胞的受损伤程度逐渐增大;同时,H₂O₂含量和过氧化氢酶的活性均有所上升,并在200 μmol·L^-1 Pb（NO₃）₂处理下达到最大值,而过氧化物酶的活性则不断降低。较之Pb（NO₃）₂胁迫下的细胞,对Pb（NO₃）₂胁迫的细胞加入外源三磷酸腺苷使得细胞受损伤程度显著降低,H₂O₂含量减少,过氧化氢酶活性减弱,而过氧化物酶活性增强。实验结果表明,Pb（NO₃）₂胁迫诱导的植物细胞损伤和H₂O₂及其清除酶水平的变化能受到细胞外三磷酸腺苷水平的调节。     

Histochemistry of Plasmalogen

Unfixed frozen sections of kidney, heart and brain from Wistar rats were used for the following tests: 1. relative reactivity of plasmalogen in different tissues to fuchsin-sulfurous acid (FSA); 2. effect of various mercury compounds in producing the plasmal reaction, and use of dithizone to verify the attachment of mercury to tissue plasmalogen; 3. effect of pH as shown by graded concentrations of HCl and by phosphate and acetate buffers; 4. effect of various cations; 5. solubility of plasmalogen in methanol, ethanol, isopropanol, n-butanol, t-butanol, n-pentanol and ethylene glycol; 6. effect of blocking reactions: acetal formation, bromination and iodination. The results showed that the amount of plasmalogen in brain is very much greater than that in heart muscle or in kidney and that the brain plasmalogen appears to be more reactive. All the highly ionized mercury compounds, HgCl₂, Hg(NO₃)₂, Hg(CH₃COO)₂, and HgNO₃ gave identical, immediate reactions. The moderately ionized K₂HgI₄ gave a less rapid reaction. Hg compounds which are unable to deliver any appreciable amount of mercuric ion into solution (nonionized or insoluble) did not react. Dithizone, which forms a deep red color in combination with Hg-containing compounds, gave a positive reaction at the same sites that gave the plasmal reaction. This indicates that the Hg combines with tissue plasmalogen. The hydrolysis of plasmalogen as a function of pH and time showed that 6 N HCl gave as rapid a reaction as HgCl₂. As the pH was increased the rate of plasmal formation decreased. At pH 4.0 no plasmal was evident in 2 hr. AuCl₃ and PdCl₂ gave reactions identical with that of HgCl₂. No other cation tested gave a plasmal reaction. Plasmalogen was rapidly dissolved by the short chain monohydric alcohols but not by ethylene glycol. Plasmalogen did not dissolve appreciably in 60% or lower grades of ethanol. Bromination or iodination abolished the plasmal reaction, but iodination required a longer time to do so. A 1.2 N HCl solution in ethylene glycol inhibited the HgCl₂-FSA reaction by the formation of an acetal which is relatively insensitive to HgCl₂, but it did not inhibit the FSA reaction when hydrolysis was by 6 N HCl instead of HgCl₂. The vinyl ether structure proposed by Rapport and associates (1957) for plasmalogen is supported by the specific reaction with HgCl₂, the hydrolysis with acid, the addition of iodine, of bromine, and the formation of an acetal.     

Diplatinum(III) complexes with bridging 1-methylcytosinate ligands and variable axial ligands, including guanine nucleobases

A series of diplatinum(III) complexes derived from cis-(NH₃)₂Pt^II and the model nucleobase 1-methylcytosine (1-MeC) has been prepared and X-ray structurally characterized, all of which contain two anionic base ligands (1-MeC⁻) in a head–tail (ht) arrangement: ht-cis-[(ONO₂)(NH₃)₂Pt(1-MeC⁻-N3,N4)₂Pt(NH₃)₂(ONO₂)](NO₃)₂·HNO₃·3H₂O (2b), ht-cis-[(NO₂) (NH₃)₂ Pt(1-MeC⁻-N3,N4)₂Pt(NH₃)₂(OH₂)](ClO₄)₃·3.5H₂O (3), ht-cis-[(OH₂)(NH₃)₂Pt(1-MeC⁻-N3,N4)₂Pt(NH₃)₂(OH₂)](ClO₄)₄·H₂O (4b), and ht-cis-[(9-EtGH-N7)(NH₃)₂Pt(1-MeC⁻-N3,N4)₂Pt (NH₃)₂(9-EtGH-N7)](NO₃)₄·9H₂O (7b) (9-EtGH=9-ethylguanine). Several other compounds, differing in the nature of the axial ligands, have been isolated and or observed in solution by ¹H and ¹⁹⁵Pt NMR spectroscopy. The chemistry of these diplatinum(III) compounds is dominated by facile substitution reactions of the axial ligands. Of particular interest in this context is the ready reaction of 2b or 3 with guanine nucleobases. Since similar compounds are not obtained with any of the other common nucleobases, 2b and 3 can be considered guanine-specific chemical probes.     

Demonstration of Pulmonary Surfactant by Tracheal Injection of Tricomplex Salt Mixture: Electron Microscopy

Laboratory animals were perfused with glutaraldehyde through the right ventricle before filling the whole lung intratracheally with a solution of 0.05 N Pb(NO₃)₂ and K₃Fe(CN)₆ and incubating it at 37 C for 30 min. An electron-dense reaction product on the surface of epithelial cells and in certain well-localized regions of the alveolar septa results. Nonspecific, intracellular, precipitates do not occur. Lungs which are sliced before glutaraldehyde fixation and immersed in the tricomplex salt mixture show patchy localization of reaction product. Diffuse, electron-dense deposits measuring 100-2000 mμ in diameter are seen in the cytoplasm of epithelial, endothelial and interstitial cells although occasionally there is localization on the surface of the epithelial cells and in specific sites within cells. Injection of the whole lung with tricomplex salt mixture after fixation with glutaraldehyde by vascular perfusion is a better method for the ultrastructural demonstration of pulmonary surfactant than immersion fixation and staining.     

Dinuclear palladium(II) complexes containing two monofunctional [Pd(en)(pyridine)Cl] units bridged by Se or S. Synthesis, characterization, cytotoxicity and kinetic studies of DNA-binding

Two novel dinuclear palladium(II) complexes, {[Pd(en)Cl]₂(bpse)}(NO₃)₂ (1) and {[Pd(en)Cl]₂ (bpsu)}(NO₃)₂ (2), (where en is ethylenediamine; bpse is bis(3-methyl-4-pyridyl) selenide; bpsu is bis(3-methyl-4-pyridyl) sulfide) have been synthesized. The complexes have been characterized by elemental analysis, IR, ¹H NMR, and ¹³C NMR. They have been assayed for antitumor activity in vitro against the mice leukemia L1210 and the human coloadenocarcinoma HCT8 cell lines. The results show that compound 1 has a lower I.D.₅₀ value against the two cancer cell lines as compared to compound 2; the compounds also shows a lower I.D.₅₀ value than cisplatin against the HCT8 cell line, but a higher I.D.₅₀ value than cisplatin against the L1210 cell line. Binding studies indicate that compound 1 possibly interacts with DNA by a nonintercalative mode. Kinetics of binding of the two compounds to DNA are firstly studied using ethidium bromide as a fluorescence probe with stopped-flow spectrophotometer under pseudo-first-order condition. The stronger binding of two steps in the process of the compounds interacting with DNA are observed, and the k_obs and E_a of binding of the two steps (where k_obs is the observed pseudo-first-order rate constant, E_a is the observed energy of activation) are obtained.     

N,N′-Ethylene-bis(3-methoxysalicylideneimine) mononuclear (4f) and heterodinuclear (3d–4f) metal complexes: Synthesis, crystal structure and luminescent properties

The stepwise synthesis of mononuclear (4f) and heterodinuclear (3d–4f) Salen-like complexes has been investigated through structural determination of the intermediate and final products occurring in the process. In the first step, reactions of ligand H₂L and Ln(NO₃)₃ · 6H₂O give rise to three mononuclear lanthanide complexes Ln(H₂L)(NO₃)₃ [H₂L = N,N′-ethylene-bis(3-methoxysalicylideneimine), Ln = Nd (1), Eu (2) and Tb (3)], in which N,N′-ethylene-bis(3-methoxysalicylideneimine) acts as tetradentate ligands with the O₂O₂ set of donor atoms capable of effective coordination. These species are fairly stable and have been isolated. Then, addition of Cu(Ac)₂ · H₂O to the mononuclear lanthanide complex yields expected heterodinuclear (3d–4f) complexes Cu(L)Ln(NO₃)₃ · H₂O [Ln = Nd (4) and Eu (5)] where the Cu(II) ion is inserted to the inner N₂O₂ cavity. Luminescent analysis reveals that complex 3 exhibits characteristic metal-centered fluorescence of Tb(III) ion. However, the characteristic luminescence of both Sm(III) and Eu(III) ions is not observed both in solution and solid state of the complexes.     

土壤湿度水平和湿-干循环对硝酸钙盐积累土壤锰释放的影响

在[Ca(NO₃)²]盐处理土壤中,研究了两种湿度水平(200、400g·kg^-1)和湿干循环对土壤Mn释放的影响.结果表明,土壤水分状况影响土壤Mn的有效性,湿度大时,易还原态Mn转化为水溶态、交换态Mn;盐分对易还原态Mn的转化有一定影响,NO₃^-能缓冲土壤Eh的下降,有抑制易还原态Mn转化的作用.连续的湿干循环能使土壤2价Mn(水溶态Mn、交换态Mn)浓度降低,而Ca(NO₃)²盐能增加Mn的不溶性.这在Mn含量低的土壤上,最终将导致Mn的缺乏.