Incomplete Substitution Research Articles

The incomplete substitution of lipopolysaccharide with O-chain prevents the establishment of effective symbiosis between Mesorhizobium loti NZP2213.1 and Lotus corniculatus

Mesorhizobium loti NZP2213.1 mutant obtained after random Tn5 mutagenesis of M. loti NZP2213 was inefficient in nitrogen fixation on Lotus corniculatus. The transposon insertion was located within an ORF with a sequence similarity to a putative glycosyl transferase from Caulobacter crescentus. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the mutant produced LPS of the same O-chain length but only half of the entire smooth LPS, compared to that of the parental strain. A greater diversity of the anomeric region as determined by NMR spectroscopy, reflected structural differences in the mutant repeating units represented by 6-deoxytalose, 2-OAc-6-deoxytalose, and 2-OMe-6-deoxytalose. In contrast to the completely O-acetylated 6-deoxytalose in wild-type OPS only partial O-acetylation was found in the mutant. The decrease of the LPS species with O-chains seems to be correlated with 6-deoxytalose deficiency. Microscopic examination of the nodules induced by the mutant revealed disturbances in infection thread development and premature senescence of symbiosomes. The impairment of mutant-induced symbiosomes to sustain latter stages of symbiosis could be a consequence of the decreased ratio of the hydrophobic to the hydrophilic LPSs.

Structure of the glycerol phosphate-containing O-polysaccharides and serological studies of the lipopolysaccharides ofProteus mirabilisCCUG 10704 (OE) andProteus vulgarisTG 103 classified into a newProteusserogroup, O54

O-Polysaccharides were obtained from the lipopolysaccharides of Proteus mirabilis CCUG 10704 (OE) and Proteus vulgaris TG 103 and studied by chemical analyses and one- and two-dimensional (1)H and (13)C nuclear magnetic resonance spectroscopy, including rotating-frame nuclear Overhauser effect spectroscopy, H-detected (1)H,(13)C heteronuclear single-quantum spectroscopy and (1)H,(31)P heteronuclear multiple-quantum spectroscopy experiments. The Proteus mirabilis OE polysaccharide was found to have a trisaccharide repeating unit with a lateral glycerol phosphate group. The Proteus vulgaris TG 103 produces a similar O-polysaccharide, which differs in incomplete substitution with glycerol phosphate (c. 50% of the stoichiometric amount) and the presence of an O-acetyl group at position 6 of the 2-acetamido-2-deoxygalactose (GalNAc) residue. These structures are unique among the known bacterial polysaccharide structures. Based on the structural and serological data of the lipopolysaccharides, it is proposed to classify both strains studied into a new Proteus serogroup, O54, as two subgroups, O54a,54b and O54a,54c. The serological relatedness of the Proteus O54 and some other Proteus lipopolysaccharides is discussed.

5V급 고전압 양극 LiNi0.5Mn1.5O4Spinel의 제조와 전기화학적 특성에 관한 연구

차세대 5V급 양극활물질로 각광받고 있는 <TEX>$LiNi_{0.5}Mn_{1.5}O_4$</TEX>는 기존의 <TEX>$LiMn_2O_4$</TEX> spinel 물질의 <TEX>$Mn^{3+}$</TEX>을 <TEX>$Ni^{2+}$</TEX>으로 치환하여 5V 영역에서 <TEX>$Ni^{2+}/Ni^{4+}$</TEX> 산화/환원 반응이 가능하게 한 물질이다. 기존의 <TEX>$LiMn_2O_4$</TEX>는 낮은 초기 용량과 충 방전에 따른 빠른 용량감소를 보이는 단점을 가지고 있어 이 문제를 극복하기 위해 Mn의 일부를 다른 금속으로 치환하여 <TEX>$LiM_yMn_{2-y}O_4$</TEX> (M=Cr, Al, Ni, Fe, Co, Cu, Ca)을 만드는 방법이 활발히 연구되고 있다. 본 연구에서는 기계 화학적 합성법을 이용하여 합성한 <TEX>$LiNi_{0.5}Mn_{1.5}O_4$</TEX>의 전기화학적 특성에 대해 연구하였다. 이 물질은 기존의 <TEX>$LiMn_2O_4$</TEX>보다 에너지 밀도가 높으며 저가 및 친환경성 등으로 앞으로 HEV 등에서 그 활용성이 크게 기대된다. 볼밀을 이용하여 여러가지 조건(출발물질 조건, 볼밀조건, 열처리조건 등)에서 <TEX>$LiNi_{0.5}Mn_{1.5}O_4$</TEX>을 합성한 결과 기계화학적 방법으로는 <TEX>$Ni^{2+}$</TEX>가 <TEX>$Mn^{3+}$</TEX>를 완전히 치환하지 못하여 <TEX>$4.0{\sim}4.1V$</TEX>의 전압에서 <TEX>$Mn^{3+}/Mn^{4+}$</TEX>의 산화/환원과 관련된 peak가 발생하였다. Ni 원료 물질로써 수산화 물질을 사용하고 열처리 온도를 <TEX>$800^{\circ}C$</TEX>로 하였을 때 최상의 성능을 나타내었다. Recently, many researches on the high-voltage 5 V class cathode material have focused on <TEX>$LiNi_{0.5}Mn_{1.5}O_4$</TEX>, where <TEX>$Mn^{3+}$</TEX> in the existing <TEX>$LiMn_2O_4 (Li[Mn^{3+}][Mn^{4+}]O_4)$</TEX> is replaced by <TEX>$Ni^{2+}(Li[Ni^{2+}]_{0.5}[Mn^{4+}]_{1.5}O_4)$</TEX> in order to utilize <TEX>$Ni^{2+}/Ni^{4+}$</TEX> redox reaction in the 5V region. The partial substitution of Mn in <TEX>$LiMn_2O_4$</TEX> for other transition metal element, <TEX>$LiM_yMn_{1-y}O_4$</TEX>(M=Cr, Al, Ni, Fe, Co, Cu, Ga etc) is known as a good solution to overcome the problems associated with <TEX>$LiMn_2O_4$</TEX> like the gradual capacity fading. In this study, we synthesized <TEX>$LiNi_{0.5}Mn_{1.5}O_4$</TEX> through a mechanochemical process and investigated its morphological, crystallographic and electrochemical characteristics. The results showed that 4 V peaks had been found in the cyclic volammograms of the synthesized powders due to the existence of <TEX>$Mn^{3+}$</TEX> from the incomplete substitution of <TEX>$Ni^{2+}$</TEX> for <TEX>$Mn^{3+}$</TEX> implying that the mechanochemical activation alone was not good enough to synthesize an exact stoichiometric compound of <TEX>$LiNi_{0.5}Mn_{1.5}O_4$</TEX>. The synthetic condition of mechanochemical process, such as type of starting materials, ball-mill and calcination condition was optimized for the best electrochemical performance.

A Combined ESI‐ and MALDI‐MS(/MS) Study of Peripherally Persulfonylated Dendrimers: False Negative Results by MALDI‐MS and Analysis of Defects

Mass spectrometry, in particular MALDI-MS, has often been used as a valuable means to characterize dendritic molecules with respect to their molecular masses. Also, it is a valuable tool for analyzing potential defects in their structure which result from incomplete synthetic steps. This article presents a comparison of ESI and MALDI mass spectrometric experiments on dendrimers persulfonylated at their periphery. While the ESI mass spectra easily permit impurities and defects to be identified and thus provide evidence for sample purity, reactions with acidic matrices occur during the MALDI process. The resulting defects are identical to those expected from incomplete substitution. Thus, in these cases, MALDI-MS yields false negative results. With mass-selected, ESI-generated ions, collision experiments were performed in an FT-ICR mass spectrometer cell to provide detailed insight into the fragmentation patterns of the various dendrimers. Different fragmentation patterns are observed depending on the exact structure of the dendrimer. Also, the nature of the charge is important. The fragmentation reactions for protonated species differ much from those binding a sodium or potassium ion. These differences can be traced back to different sites for binding H+ versus Na+ or K+. Tandem MS experiments on mass-selected dendrimer ions with defects can be used to distinguish different types of defects. A concise structural assignment can thus be made on the basis of these experiments. Even mixtures of two isobaric defect variants with the same elemental composition can be identified.

Reaction of Potassium Salts of N-(Thio)phosphorylthioamides with Chlorinated 1,3,5-Triazines

Potassium salts of N-(thio)phosphorylthioamides can substitute one, two, or three halogen atoms in chlorinated 1,3,5-triazine molecules to give the products of imidothiyl structure. At low temperature, products of incomplete substitution of halogen in the starting 1,3,5-triazines can be obtained.

Ru(II) complexes of polyarylated terpyridines: unexpected side-chain C-metallation and photosensitization of electron transfer

The new ligands 4,4″-diphenyl-6,6″-di(4-ethoxycarbonylphenyl)-2,2′:6′,2″-terpyridine (H 4), its non-carboxylated 4,6,4″,6″-tetraphenyl analogue (H 5) and the 4,4″-diphenyl-6,6″-di(4-methoxyphenyl) analogue were prepared in high yields via double Kröhnke reactions. Reactions with activated (ttpy)RuCl 3 (ttpy is 4′- p-tolyl-2,2′:6′,2″-terpyridine) provided the symmetrical N 6-coordinated complexes, [Ru(H 4)(ttpy)](PF 6) 2 and [Ru(H 5)(ttpy)](PF 6) 2, along with the novel, unsymmetrical C-metallated analogues [Ru( 4)(ttpy)]PF 6 and [Ru( 5)(ttpy)]PF 6, in which an unprecedented side-chain metallation occurred in lieu of incomplete substitution. A crystallographic analysis of [Ru( 5)(ttpy)]NO 3 confirmed the N 5 C donor set in these products and revealed a distorted binding of 5 − as well as ‘π-stacking’ between its uncoordinated pyridine and the ttpy ligand. The diester [Ru(H 4)(ttpy)](PF 6) 2 was hydrolyzed to the diacid complex [Ru(H 2 3)(ttpy)](PF 6) 2 (H 2 3 is 4,4″-diphenyl-6,6″-di(4-carboxyphenyl)-2,2′:6′,2″-terpyridine). Measurements of the photogeneration of methyl viologen cation radical with [Ru(H 5)(ttpy)](PF 6) 2 and [Ru(H 2 3)(ttpy)](PF 6) 2 as sensitizers showed that the presence of carboxyl groups in the latter provided a distinct benefit, owing to the formation of the neutral form [Ru( 3)(ttpy)] 0 but this was insufficient to overcome the detrimental effect of inter-ligand repulsions.

The structure of the core part of Proteuspenneri strain 16 lipopolysaccharide

The structure of the carbohydrate backbone of the lipid A-core region of the lipopolysaccharide (LPS) from Proteus penneri strain 16 was determined using NMR and chemical analysis of the core oligosaccharide, obtained by mild acid hydrolysis of the LPS, and of the products of alkaline deacylation of the LPS: Incomplete substitution is indicated by bold italics. All sugars are in the pyranose form, α-Hep is the residue of l- glycero-α- d- manno-Hep, α- dd-Hep is the residue of d- glycero-α- d- manno-Hep, Bu is the ( R)-3-hydroxybutyryl residue.

Effects of Cd‐Substitution Site on the Electrical Conductivities in Pb(Ni1/3Nb2/3)O3‐PbZrO3‐PbTiO3 Ceramics

The effects of Cd2+ substitution for Pb2+ and Ni2+ ions (on the A‐site and B‐site of the ABO3 perovskite structure, respectively) on the electrical conductivities in Pb(Ni1/3‐Nb2/3)O3‐PbZrO3‐PbTiO3 (PNN‐PZ‐PT) ceramics have been investigated. Generally, the compounds that contain PbO show p‐type conductivity, because of PbO evaporation. Thus, the conductivities are known to be proportional to the PbO evaporation. However, PNN‐PZ‐PT ceramics exhibit a reciprocal relationship between the conductivities and the evaporation of PbO. Generally, no vacancy change is observed with the substitution of the same‐charge valence ion. However, in the PNN‐PZ‐PT ceramic, lead vacancies could be created or annihilated by replacing Pb2+ and Ni2+ ions with Cd2+ ions, because of incomplete substitution. The electrical conductivities are influenced by this incomplete substitution.

Effects of Cd-substitution Site on PbO Evaporation in Pb(Ni1/3Nb2/3)O3–PbZrO3–PbTiO3 Ceramics

The effects of Cd2+ substitution site on PbO evaporation was investigated in Pb(Ni1/3Nb2/3)O3–PbZrO3–PbTiO3 (PNN–PZ–PT) ceramics. Generally no vacancy change is observed with substitution of the same charge valence ion. But in this case it was found that Vpb vacancy could be created or annihilated by replacing of the same charge valence ion due to the incomplete substitution. PbO evaporation was influenced by this incomplete substitution. In case of A-site substituted sample PbO activity decreased due to the increase of VA-site(Pb)′′, and PbO was condensed from the atmosphere powder into the sample, and in B-site substituted sample PbO activity increased, and the promotion of PbO evaporation occurred.

Effects of urotropin on the chemical and microstructural properties of Fe-oxide powders prepared by the hydrolysis of aqueous FeCl 3 solutions

The effects of urotropin (hexamethylenetetramine) on the chemical and microstructural properties of Fe-oxide powders, prepared by FeCl 3 hydrolysis in aqueous solutions at 90°C, were investigated using X-ray powder diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy (FTIR) and 57Fe Mössbauer spectroscopy. In the absence of urotropin, akaganéite ( β-FeOOOH) particles showed different morphologies, such as spindles, stars, X- and Y-shapes. After 5 h of aging and for an initial 0.025 M urotropin concentration, acicular β-FeOOH particles (monodispersed) of decreased size were obtained. For the same aging time and 0.25 M urotropin the particles were amorphous for X-ray diffraction, while 57Fe Mössbauer spectroscopy indicated that these particles were of very small dimensions (super paramagnetic) and probably of the FeOOH structure. The β-FeOOH formation at pH values significantly higher than pH = 2 was explained by incomplete substitution of CI − ions in Fe (III)-hydroxy polymers with OH − ions. No evidence of organic components on the solid hydrolytical products was detected by FTIR spectroscopy. After 7 days of aging and for an initial urotropin concentration of up to 0.025 M, β-FeOOH wa also obtained as a single phase, while for c≥ 0.1 M urotropin mixtures of goethite ( α-FeOOH) and haematite ( α-Fe 2O 3) were formed. Phase transformations β-FeOOH → α-Fe 2O 3 and β-FeOOH → α-FeOOH → α-Fe 2O 3 were discussed in the sense of the dissolution/precipitation mechanism.

The establishment of 10-500/√3kV power frequency voltage ratio standard apparatus and study of the calibration method

The principle of 10-500//spl radic/3-kV power frequency voltage ratio standard apparatus and the calibration method at NHVMS, China, are presented in this paper. The substitution method which is usually used for low-voltage precise measurement was applied to the field of high-voltage measurement. A new method was developed. It is renamed "the incomplete substitution method" because the operating voltages and currents of the components of the standard apparatus are different before and after substitution. The systematic errors of the components due to the difference of operating states are measured in advance and can be corrected, so the measuring accuracy is improved greatly. The error analysis shows that the total uncertainties of the standard apparatus are better than /spl plusmn/10 ppm in magnitude and /spl plusmn/10 /spl mu/rad in phase angle (the confidence factor is 3). The comparison result between China and Canada is satisfactory.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A rietveld study of the cation substitution between uvarovite and yttrium‐aluminum synthetic garnets, obtained by sol‐gel method

AbstractA series of synthetic garnets solid solutions is compositions between Y3Al2Al3O12 (Y‐Al garnet) (YAG) and Ca3Cr2Si3O12 (uvarovite) was synthesized using the sol‐gel method. The expected general formula is (CaxY1‐x)3 (CrxAl1‐x)2 (SixAl1‐x)3O12 where x = 0 to x = 1.The cation distribution in dodecahedral, octahedral and tetrahedral sites and bond distances in these synthetic garnets were determined using the Rietveld method. It shows the incomplete substitution in small sites. The smaller site the smaller substitution there is.

O‐specific polysaccharide of Hafnia alvei lipopolysaccharide isolated from strain 1211

The Hafnia alvei strain 1211 O-specific polysaccharide is composed of 3-amino-N-(D-3'-hydroxybutyryl)-3,6-dideoxy-D-galactose, N-acetyl-D-galactosamine, N-acetyl-D-glucosamine and D-glucose (1:1:2:2). On the basis of sugar and methylation analyses, Smith degradation, and one- and two-dimensional 1H- and 13C-NMR spectroscopy, the polysaccharide was shown to be an O-acetylated polymer of the repeating hexasaccharide unit, ----2D(4-OAc)Fucp3NAcyl beta 1----6DGlcpNAc alpha 1---- (DGlcp beta 1----3)4DGalpNAc alpha 1----3DGlcpNAc beta 1----2DGlcp beta 1----, where DFucp3NAcyl = 3-amino-N-(D-3'-hydroxybutyryl)-3,6-dideoxy-D- galactopyranose. The O-specific polysaccharide showed some microheterogeneity due to incomplete substitution by terminal glucose.

Terguride, a dopamine D2 partial agonist, as a discriminative stimulus in rats

Drug discrimination training with terguride, a 9, 10-transdihydrogenated derivative of lisuride, was carried out using a two-lever food-reinforced procedure (FR 10) in rats, to investigate its influence on central dopaminergic (DA) and serotonergic (5-HT) functions. The terguride (0.05mg/kg, i.p.) discrimination was established within 64 +/- 5 training sessions (mean +/- S.E.) and was stably maintained thereafter. Higher doses of terguride could not be used for discriminative training due to response disruption. In generalization tests with terguride, drug-appropriate responding increased dose-dependently and reached levels of 45 and 99% at 0.01 and 0.05mg/kg i.p. The D(2) agonist lisuride at low doses and the DA autoreceptor agonist (-)-3-PPP substituted for terguride. The DA agonist apomorphine and the 5-HT agonist 5-MeO-DMT produced dose-dependent but incomplete substitution. The D(1) agonist SKF38393, the DA antagonist haloperidol, the D(2) antagonist sulpiride, the D(1) antagonist SCH23390, the 5-HT(1A) agonist 8-OH-DPAT, the 5-HT(1B) agonist m-CPP and the 5-HT(2) agonist DOI were not generalized. In antagonism tests, sulpride completely blocked the terguride-appropriate response, but SCH23390 and the 5-HT antagonist methysergide did not. These results indicate that discriminative stimulus properties of terguride in rats are mediated primarily by activation of receptors with characteristics similar to those of presynaptic D(2) autoreceptors.

ChemInform Abstract: Synthesis of Isoxazolylphosphazene.

The reaction of phosphonitrilic dichloride cyclic trimer with 4-hydroxymethyl-3,5-disubstituted isoxazoles leads to incomplete substitution,and forcing conditions gave rise to fragmentation to the corresponding 4-chloromethylisoxazole derivatives.Two carbon homologation of the C-4 isoxazole moiety,followed by reaction with (1) produced the hexakis-substituted product(9).Preliminary studies indicate that (9) functions as a ligand in complexes with co(II),Cr(III) and Mn(III)

Synthesis of Isoxazolylphosphazene

The reaction of phosphonitrilic dichloride cyclic trimer with 4-hydroxymethyl-3,5-disubstituted isoxazoles leads to incomplete substitution,and forcing conditions gave rise to fragmentation to the corresponding 4-chloromethylisoxazole derivatives.Two carbon homologation of the C-4 isoxazole moiety,followed by reaction with (1) produced the hexakis-substituted product(9).Preliminary studies indicate that (9) functions as a ligand in complexes with co(II),Cr(III) and Mn(III)

Effects of offering different amounts and types of supplemental feeds to growing dairy steers fed endophyte-infected fescue hay ad libitum on intake, digestion, passage rate and serum prolactin concentration.

Ten Holstein steers (141 kg) were used in two 5 X 5 Latin-square experiments conducted simultaneously to determine the effects of offering different levels and types of feeds with endophyte-infected fescue given ad libitum. In Exp. 1, steers were given ad libitum access to infected fescue hay in the afternoon; in the morning fescue was given ad libitum (basal) or bermudagrass or clover hays were fed at .5 or 1.0% of body weight (BW). Supplementation did not affect total dry matter intake (P greater than .10), but supplementation at 1.0% of BW yielded total intake greater than supplementation at .5% of BW (P less than .05). Supplementation did not change digestibilities of dry or organic matter (P greater than .10). Particulate passage rate was greater (P less than .10) with supplementation at 1.0 than at .5% of BW, and increasing the level of supplementation from .5 to 1.0% of BW affected fluid passage rate positively with clover but negatively with bermudagrass (interaction, P less than .05). Serum prolactin increased (P less than .05) with all supplementation treatments, although no differences were observed between supplement type-supplementation level combinations (P greater than .10). Ground corn and wheat hay were supplements in Exp. 2. Total intake of dry matter was greater with supplements provided at 1.0 rather than at .5% of BW and for corn rather than wheat hay (P less than .05). Neutral detergent fiber digestion (percent of intake and grams per day) rose when wheat hay was offered at 1.0 vs .5% of BW but declined when the level of supplemental corn increased from .5 to 1.0% of BW (interaction, P less than .05). There were no differences among diets in particulate and fluid passage rates and serum prolactin concentration. Supplementation with nontoxic forage of a basal diet of infected fescue yielded intake substitution when forage was offered at .5% of BW, although incomplete substitution occurred with 1.0% of BW of supplemental forage such that total intake increased as compared to the lower level of supplementation.

Core region of Citrobacter lipopolysaccharide from strain PCM 1487. Structure elucidation by two-dimensional 1H-NMR spectroscopy at 500 MHz and methylation analysis/mass spectrometry.

The core structure of Citrobacter PCM 1487 lipopolysaccharide has been established using methylation analysis/mass spectrometry, chemical degradations and one- and two-dimensional 1H-NMR spectroscopy at 500 MHz. 1H-NMR assignments are given for all sugar components of the core oligosaccharide. In the formula shown below, the alternative locations of branch terminal heptose (LDHep) and diphosphorylethanolamine (PPEtN) residues are marked by dashed lines; dOclA stands for 3-deoxy-D-manno-octulosonic acid. (Formula: see text). The sample of the core oligosaccharide showed some microheterogeneity due to a slightly incomplete substitution by terminal N-acetylgalactosamine and a partial splitting of diphosphorylethanolamine residues.

IR spectroscopic study of hydration of cellulose acetates and polyvinyl acetate

By differential recording of spectra of moistened, relatively similar dry samples absorption spectra were obtained and interpreted of water, absorbed by cellulose acetates of different degrees of substitution and by PVA. It was established that water molecules adsorbed by triacetate and PVA interact via weak hydrogen bonds with CO groups of polymers. Both OH bonds of water molecules are disturbed to about the same extent by hydrogen bridges. Cellulose acetate with incomplete substitution is characterized by interaction of water molecules both with CO groups and with unsubstituted hydroxy groups. However, asymmetry in the stress of OH bonds of the water molecule is observed in associates with hydroxyls. Hydration with high relative humidity values (>50%) is accompanied by the formation of hydrate structures on previously adsorbed molecules. It was shown that water adsorption by cellulose acetate films may change the three-dimensional arrangement of acetate groups and increase the degree of orientation ordering of polymer structure.

IR-spectral study of the hydration of cellulose nitrates

The sorption spectra of water sorbed by cellulose nitrates were produced and interpreted as a function of the relative moisture content of air and the nitrogen content by recording the spectra of a moistened sample relative to the same sample in a dry state. The main feature in the case of samples with an incomplete substitution was the interaction of water molecules with the unsubstituted hydroxyl; only one H-bond of the H 2O molecule participated in H-bond formation where the % hydration was low. The spectra of hydrated samples with a large nitrogen content showed absorption lines for the water molecules which were distorted by weak H-bonds with the nitrate groups. The resulting complexes have been identified. The hydrations at larger relative humidities (>50%) yield hydrate structures on the earlier sorbed water molecules.