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1.
Phys Rev Lett ; 123(4): 047203, 2019 Jul 26.
Artigo em Inglês | MEDLINE | ID: mdl-31491273

RESUMO

The recent discovery of intrinsic ferromagnetic order in the atomically thin van der Waals crystal CrXTe_{3} (X=Si, Ge) stimulates intensive studies on the nature of low-dimensional magnetism because the presence of long-range magnetic order in two-dimensional systems with continuous symmetry is strictly prohibited by thermal fluctuations. By combining advanced many-body calculations with angle-resolved photoemission spectroscopy we investigate CrSiTe_{3} single crystals and unveil the pivotal role played by the strong electronic correlations at both high- and low-temperature regimes. Above the Curie temperature (T_{c}), Coulomb repulsion (U) drives the system into a charge transfer insulating phase. In contrast, below T_{c} the crystal field arranges the Cr-3d orbitals such that the ferromagnetic superexchange profits, giving rise to the bulk ferromagnetic ground state with which the electronic correlations compete. The excellent agreement between theory and experiment establishes CrSiTe_{3} as a prototype low-dimensional crystal with the cooperation and interplay of electronic correlation and ferromagnetism.

2.
ACS Nano ; 13(9): 10705-10710, 2019 Sep 24.
Artigo em Inglês | MEDLINE | ID: mdl-31469545

RESUMO

Two-dimensional (2D) materials with narrow band gaps (∼0.3 eV) are of great importance for realizing ambipolar transistors and mid-infrared (MIR) detections. However, most of the 2D materials studied to date have band gaps that are too large. A few of the materials with suitable band gaps are not stable under ambient conditions. In this study, the layered Nb2SiTe4 is shown to be a stable 2D material with a band gap of 0.39 eV. Field-effect transistors based on few-layer Nb2SiTe4 show ambipolar transport with a similar magnitude of electron and hole current and a high charge-carrier mobility of ∼100 cm2 V-1 s-1 at room temperature. Optoelectronic measurements of the devices show clear response to an MIR wavelength of 3.1 µm with a high responsivity of ∼0.66 AW-1. These results establish Nb2SiTe4 as a good candidate for ambipolar devices and MIR detection.

3.
ACS Appl Mater Interfaces ; 10(15): 12831-12838, 2018 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-29569894

RESUMO

Different two-dimensional (2D) materials, when combined together to form heterostructures, can exhibit exciting properties that do not exist in individual components. Therefore, intensive research efforts have been devoted to their fabrication and characterization. Previously, vertical and in-plane 2D heterostructures have been formed by mechanical stacking and chemical vapor deposition. Here, we report a new material system that can form in-plane p-n junctions by thermal conversion of n-type SnSe2 to p-type SnSe. Through scanning tunneling microscopy and density functional theory studies, we find that these two distinctively different lattices can form atomically sharp interfaces and have a type II to nearly type III band alignment. We also demonstrate that this method can be used to create micron-sized in-plane p-n junctions at predefined locations. These findings pave the way for further exploration of the intriguing properties of the SnSe2-SnSe heterostructure.

4.
Sichuan Da Xue Xue Bao Yi Xue Ban ; 48(1): 61-65, 2017 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-28612560

RESUMO

OBJECTIVES: To construct the prokaryotic expression system of estrogen receptor α ligand bingding domain (hERα-LBD) and to evaluate the estrogen receptor ligand binding activity of the expressed protein. METHODS: hERα -LBD was amplicated from the plasmid of hERα -LBD by PCR, the identified PCR product was ligated with pGEM-T-easy vector to generate pGM-T-hERα -LBD. After the confirmation, the hERα -LBD fragments were obtained by enzyme digestion and inserted into pET-28a. The expression vectors were expressed in E.Coli to produce hERα-LBD protein. We mixed the hERα-LBD protein and estradiol and bovine serum albumin conjugated antigens (E2-BSA), then evaluated the binding activity of hERα-LBD by electrophoresis. RESULTS: The amplified fragment was about 1.9 kb, which was in agreement with the expected target fragment. Recombinant plasmid of pGM-T-hERα -LBD was confirmed by enzyme digestion and sequencing, then pET-28a(+)-hERα -LBD was constructed successfully. The expressed hERα-LBD protein in E.Coli was observed and the expression amount was 250 mg/L after affinity chromatography purification. hERα-LBD was confirmed to had estrogen binding activity by electrophoresis. CONCLUSIONS: The prokaryotic expression system of pET-28a(+)-hERα -LBD was successfully constructed, and hERα-LBD had the activity of binding.


Assuntos
Receptor alfa de Estrogênio/genética , Vetores Genéticos , Escherichia coli , Ligantes , Plasmídeos , Reação em Cadeia da Polimerase
5.
Prep Biochem Biotechnol ; 46(5): 509-16, 2016 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-26460578

RESUMO

A plasma jet, driven by an active helium atom supplied with an atmospheric and room temperature plasma (ARTP) biological breeding system, was used as a novel method to breed L-arginine high-yielding strains. A mutant with resistance to L-homoarginine and 8-azaguaine, ARG 3-15 (L-HA(r), 8-AG(r), L-His(-)), was screened after several rounds of screening. The L-arginine production of these mutants was more than that of the original strain, increased by 43.79% for ARG 3-15. Moreover, N-acetyl-L-glutamate synthase activity of these mutants was also increased. After a series of passages, the hereditary properties of these mutants were found to be stable. Interestingly, beet molasses was utilized in a co-feeding fermentation and benefited to increase the productivity by 5.88%. Moreover, the fermentation with 1.0 g/L betaine could produce 9.33% more L-arginine than without betaine. In fed-batch fermentation, C. glutamicum ARG 3-15 began to produce L-arginine at the initial of logarithmic phase, and continuously increased over 24 hr to a final titer of 45.36 ± 0.42 g/L. The L-arginine productivity was 0.571 g/L/hr and the conversion of glucose (α) was 32.4% after 96 hr. These results indicated that C. glutamicum ARG 3-15 is a promising industrial producer.


Assuntos
Arginina/biossíntese , Corynebacterium glutamicum/metabolismo , Mutagênese , Corynebacterium glutamicum/genética , Meios de Cultura , Fermentação
6.
Inorg Chem ; 54(16): 8012-21, 2015 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-26241691

RESUMO

Perovskite materials provide a large variety of interesting physical properties and applications. Here, we report on unique properties of a fully ordered magnetodielectric double-perovskite, Sc2NiMnO6 (space group P21/n, a = 4.99860 Å, b = 5.35281 Å, c = 7.34496 Å, and ß = 90.7915°), exhibiting sequential magnetic transitions at T1 = 35 K and T2 = 17 K. The transition at T1 corresponds to a single-k antiferromagnetic phase with propagation vector k1 = (1/2, 0, 1/2), while the second transition at T2 corresponds to a 2-k magnetic structure with propagation vectors k1 = (1/2, 0, 1/2) and k2 = (0, 1/2, 1/2). Symmetry analysis suggests that the two ordering wave vectors are independent, and calculations imply that k1 is associated with the Mn sublattice and k2 with the Ni sublattice, suggesting that Mn-Ni coupling is very small or absent. A magnetodielectric anomaly at T2 likely arises from an antiferroelectric ordering that results from the exchange-striction between the two magnetic sublattices belonging to k1 and k2. The behavior of Sc2NiMnO6 demonstrates 3d double-perovskites with small A-site cations as a promising avenue in which to search for magnetoelectric materials.

7.
World J Microbiol Biotechnol ; 31(9): 1369-77, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26070433

RESUMO

Isoleucine synthesis is strongly regulated by its end product (isoleucine) in Corynebacterium glutamicum, especially at threonine dehydratase (TD) node. Multiple alignments of TD sequences of C. glutamicum and other sources were performed. According to the structural analysis, three TD variants were constructed by site-directed mutagenesis. These TD variants improved the performance of the holoenzyme. The specific activity of V140M variant was 1.5-fold higher than that of the wild-type TD, whereas F383A variant showed complete resistance to feedback inhibition by isoleucine. V140M-F383A variant had all the advantages of V140M and F383A variants and displayed 1.5-fold specific activity and complete resistance to isoleucine. In C. glutamicum, overexpression of V140M, F383A, and V140M-F383A variants accumulated 0.55, 0.63, and 0.73 g/l isoleucine, and overexpression of wild-type TD produced 0.47 g/l isoleucine. Thus, these novel TD variants, particularly V140M-F383A, showed great potential in isoleucine synthesis.


Assuntos
Corynebacterium glutamicum/metabolismo , Isoleucina/biossíntese , Mutação , Treonina Desidratase/genética , Treonina Desidratase/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Corynebacterium glutamicum/genética , Humanos , Engenharia de Proteínas/métodos , Alinhamento de Sequência
8.
Protein Expr Purif ; 109: 106-12, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25697867

RESUMO

Acetohydroxy acid synthase (AHAS) controls carbon flux through the branch point and determines the relative rates of the synthesis of isoleucine, valine and leucine, respectively. However, it is strongly regulated by its end products. In this study, we characterized AHAS variants from five branched-chain amino acids-producing strains. Amino acid substitution occurred in both catalytic subunit and regulatory subunit. Interestingly, AHAS variants reduced sensitivity to feedback inhibition by branched-chain amino acids (BCAAs). Although AHAS with amino acid substitution in regulatory subunit showed higher resistance, amino acid substitution in catalytic subunit could also endow AHAS with resistance to feedback inhibition. In addition, AHAS variants from V2 and L5 displayed about 1.4-fold higher specific activity compared to other AHAS variants. On the other hand, AHAS variant from V1 exhibited the highest resistance to BCAAs, 87% of original activity left even in the presence of 10mM BCAAs. Recombinant Corynebacteriumglutamicum strains were further constructed to investigate the effects of expressing AHAS variants on the synthesis of BCAAs and alanine (main by-product) in C. glutamicum. BCAAs production was increased with the increase of resistance to feedback inhibition, although valine showed a significant increase. For instance, C. g-1BN could accumulate 9.51g/l valine, 0.450g/l leucine and 0.180g/l isoleucine, and alanine was reduced to 0.477g/l. These AHAS variants are important for further improving performance of BCAAs-producing strain.


Assuntos
Acetolactato Sintase/metabolismo , Aminoácidos de Cadeia Ramificada/biossíntese , Corynebacterium glutamicum/enzimologia , Proteínas Mutantes/metabolismo , Eletroforese em Gel de Poliacrilamida , Homologia de Sequência de Aminoácidos
9.
Acta Crystallogr E Crystallogr Commun ; 71(Pt 12): m213-4, 2015 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-26870430

RESUMO

The Fe atom in the title ferrocene derivative, [Fe(C11H15O2)2], is situated on an inversion centre. As a result of the point-group symmetry -1 of the mol-ecule, the ferrocene moiety adopts a staggered conformation. The average Fe-C(Cp) bond length (Cp is cyclo-penta-dien-yl) is 2.045 (4) Å, in agreement with that of other disubstituted ferrocenes. The Fe-C bond length involving the substituted C atom is slightly longer [2.0521 (17) Å] than the remaining Fe-C bond lengths caused by the inductive effect of the methyl-ene group on the Cp ring. Apart from van der Waals forces, no significant inter-molecular inter-actions are observed in the crystal packing.

10.
Inorg Chem ; 53(21): 11616-25, 2014 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-25337807

RESUMO

The polycrystalline MO2's (HP-PdF2-type MO2, M = Rh, Os, Pt) with high-pressure PdF2 compounds were successfully synthesized under high-pressure conditions for the first time, to the best of our knowledge. The crystal structures and electromagnetic properties were studied. Previously unreported electronic properties of the polycrystalline HP-PdF2-type RuO2 and IrO2 were also studied. The refined structures clearly indicated that all compounds crystallized into the HP-PdF2-type structure, M(4+)O(2-)2, rather than the pyrite-type structure, M(n+)(O2)(n-) (n < 4). The MO2 compounds (M = Ru, Rh, Os, Ir) exhibited metallic conduction, while PtO2 was highly insulating, probably because of the fully occupied t2g band. Neither superconductivity nor a magnetic transition was detected down to a temperature of 2 K, unlike the case of 3d transition metal chalcogenide pyrites.

11.
J Microbiol Biotechnol ; 24(10): 1368-76, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25022526

RESUMO

This article focuses on the effects of glycine betaine on preventing caramelization, and increasing DCW and L-lysine production. The additional glycine betaine not only decreased the browning intensity (decreased 4 times), and the concentrations of 5-hydroxymethylfurfural (decreased 7.8 times) and furfural (decreased 12 times), but also increased the availability of glucose (increased 17.5%) for L-lysine production. The DCW and L-lysine production were increased by adding no more than 20 mM glycine betaine, whereas the DCW and L-lysine production were decreased with the reduction of pH values, although pH had a better response to prevent caramelization than did glycine betaine. For L-lysine production, the highest increase (40%) was observed on the media with 20 mM glycine betaine. The crucial enzymes in glycolysis and L-lysine biosynthesis pathway were investigated. The results indicated that additional glycine betaine increases the activity of enzymes in glycolysis, in contrast to the effect of pH. All the results indicated that glycine betaine can be used to prevent caramelization and increase the L-lysine production. By applying this strategy, glucose would not be have to be separated from the culture media during autoclaving so that factories can save production costs and shorten the fermentation period.


Assuntos
Betaína/metabolismo , Fermentação/efeitos dos fármacos , Lisina/metabolismo , Vias Biossintéticas/efeitos dos fármacos , Meios de Cultura/química , Glicólise/efeitos dos fármacos , Concentração de Íons de Hidrogênio
12.
Amino Acids ; 46(9): 2165-75, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24879631

RESUMO

The experiments presented here were based on the conclusions of our previous results. In order to avoid introduction of expression plasmid and to balance the NADH/NAD ratio, the NADH biosynthetic enzyme, i.e., NAD-dependent glyceraldehyde-3-phosphate dehydrogenase (GADPH), was replaced by NADP-dependent GADPH, which was used to biosynthesize NADPH rather than NADH. The results indicated that the NADH/NAD ratio significantly decreased, and glucose consumption and L-lysine production drastically improved. Moreover, increasing the flux through L-lysine biosynthetic pathway and disruption of ilvN and hom, which involve in the branched amino acid and L-methionine biosynthesis, further improved L-lysine production by Corynebacterium glutamicum. Compared to the original strain C. glutamicum Lys5, the L-lysine production and glucose conversion efficiency (α) were enhanced to 81.0 ± 6.59 mM and 36.45% by the resulting strain C. glutamicum Lys5-8 in shake flask. In addition, the by-products (i.e., L-threonine, L-methionine and L-valine) were significantly decreased as results of genetic modification in homoserine dehydrogenase (HSD) and acetohydroxyacid synthase (AHAS). In fed-batch fermentation, C. glutamicum Lys5-8 began to produce L-lysine at post-exponential growth phase and continuously increased over 36 h to a final titer of 896 ± 33.41 mM. The L-lysine productivity was 2.73 g l(-1) h(-1) and the α was 47.06% after 48 h. However, the attenuation of MurE was not beneficial to increase the L-lysine production because of decreasing the cell growth. Based on the above-mentioned results, we get the following conclusions: cofactor NADPH, precursor, the flux through L-lysine biosynthetic pathway and DCW are beneficial to improve L-lysine production in C. glutamicum.


Assuntos
Corynebacterium glutamicum , Lisina , Engenharia Metabólica , NAD , Corynebacterium glutamicum/genética , Corynebacterium glutamicum/metabolismo , Lisina/biossíntese , Lisina/genética , NAD/genética , NAD/metabolismo
13.
Plasmid ; 72: 9-17, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24613758

RESUMO

A method for the simultaneous replacement of a given gene by a target gene, leaving no genetic markers, has been developed. The method is based on insertional inactivation and double-crossover homologous recombination. With this method, the lysC(T311I), fbp and ddh genes were inserted into Corynebacterium glutamicum genome, and the pck, alaT and avtA genes were deleted. Mobilizable plasmids with lysC(T311I), fbp and ddh cassettes and two homologous arms on the ends of pck, alaT and avtA were constructed, and then transformed into C. glutamicum. The target-expression cassettes were inserted in the genome via the first homologous recombination, and the genetic markers were removed via the second recombination. The target-transformants were sequentially screened from kanamycin-resistance and sucrose-resistance plates. The enzyme activities of transformants were stably maintained for 30 generations under non-selective culture conditions, suggesting that the integrated cassettes in host were successfully expressed and maintained as stable chromosomal insertions in C. glutamicum. The target-transformants were used to optimize the l-lysine production, showing that the productions were strongly increased because the selected genes were closely linked to l-lysine production. In short, this method can be used to construct amino acid high-producing strains with unmarked gene amplification and simultaneous deletion in genome.


Assuntos
Corynebacterium glutamicum/genética , Amplificação de Genes , Deleção de Genes , Genes Bacterianos , Clonagem Molecular , Corynebacterium glutamicum/crescimento & desenvolvimento , Engenharia Genética , Marcadores Genéticos , Genoma Bacteriano , Recombinação Homóloga , Lisina/biossíntese , Plasmídeos/genética , Transformação Bacteriana
14.
J Am Chem Soc ; 136(9): 3326-9, 2014 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-24552166

RESUMO

5d and 3d hybrid solid-state oxide Ca2FeOsO6 crystallizes into an ordered double-perovskite structure with a space group of P21/n with high-pressures and temperatures. Ca2FeOsO6 presents a long-range ferrimagnetic transition at a temperature of ~320 K (T(c)) and is not a band insulator, but is electrically insulating like the recently discovered Sr2CrOsO6 (T(c) ~725 K). The electronic stat of Ca2FeOsO6 is adjacent to a half-metallic state as well as that of Sr2CrOsO6. In addition, the high-T(c) ferrimagnetism was driven by lattice distortion, which was observed for the first time among double-perovskite oxides and represents complex interplays between spins and orbitals. Unlike conventional ferrite and garnet, the interplays likely play a pivotal role of the ferrimagnetism. A new class of 5d-3d hybrid ferrimagnetic insulators with high-T(c) is established to develop practically and scientifically useful spintronic materials.

15.
Environ Technol ; 34(13-16): 2135-43, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24350467

RESUMO

Separation of municipal solid waste has been implemented in many cities in China. As a major component of municipal solid waste, food waste can be treated by anaerobic digestion (AD) for energy production. To provide reference data for disposing of food waste through engineering applications, continuous AD was carried out under various organic loading rates (OLRs) at 27 +/- 2 degrees C in the laboratory. The anaerobic reactor was stable with pH 7.0-7.1, total volatile fatty acid (VFA) concentrations of 206-746 mg/L, and NH4+ -N concentrations of 525-1293 mg/L when the OLR was 1.118-5.588 kg volatile solids (VS)/m(3) x d. The maximum volumetric biogas production rate was 4.41 L/L x d when the OLR was increased to 5.588 kg VS/m(3) x d with a hydraulic retention time of 30 d. When the OLR was increased to 6.706 and 8.382 kg VS/m(3) x d, biogas production was seriously inhibited by VFAs, with maximum total VFA and propionate concentrations of 8738 mg/L and 2864 mg/L, respectively. Due to the incomplete degradation of lipids, the specific methane production rate of 353-488 L/kg VS accounted for 55.2-76.3% of the theoretical methane potential calculated based on the component composition. A retrofitted anaerobic digester with lipid removal was designed to improve the efficiency.


Assuntos
Biocombustíveis , Reatores Biológicos , Lipídeos/química , Eliminação de Resíduos/métodos , Amônia/análise , Amônia/metabolismo , Anaerobiose , Alimentos , Concentração de Íons de Hidrogênio , Metabolismo dos Lipídeos , Metano/análise , Metano/metabolismo
16.
J Am Chem Soc ; 135(44): 16507-16, 2013 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-24090137

RESUMO

In continuation of the series of perovskite oxides that includes 3d(4) cubic BaFeO3 and 4d(4) cubic BaRuO3, 5d(4) cubic BaOsO3 was synthesized by a solid-state reaction at a pressure of 17 GPa, and its crystal structure was investigated by synchrotron powder X-ray diffraction measurements. In addition, its magnetic susceptibility, electrical resistivity, and specific heat were measured over temperatures ranging from 2 to 400 K. The results establish a series of d(4) cubic perovskite oxides, which can help in the mapping of the itinerant ferromagnetism that is free from any complication from local lattice distortions for transitions from the 3d orbital to the 5d orbital. Such a perovskite series has never been synthesized at any d configuration to date. Although cubic BaOsO3 did not exhibit long-range ferromagnetic order unlike cubic BaFeO3 and BaRuO3, enhanced feature of paramagnetism was detected with weak temperature dependence. Orthorhombic CaOsO3 and SrOsO3 show similar magnetic behaviors. CaOsO3 is not as conducting as SrOsO3 and BaOsO3, presumably due to impact of tilting of octahedra on the width of the t2g band. These results elucidate the evolution of the magnetism of perovskite oxides not only in the 5d system but also in group 8 of the periodic table.

17.
Chemistry ; 19(46): 15467-71, 2013 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-24127220

RESUMO

Magnetize your chemistry! A facile hydrothermal synthetic route was developed for the synthesis of uniform NiS2 hollow spheres, which could be transformed into NiSe2 and NiTe2 hollow spheres through a chemical conversion process. Furthermore, NiS and NiO hollow spheres could be selectively obtained by calcination of NiS2 hollow spheres at different temperatures.

18.
Nat Mater ; 12(11): 1024-7, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24056805

RESUMO

Metals cannot exhibit ferroelectricity because static internal electric fields are screened by conduction electrons, but in 1965, Anderson and Blount predicted the possibility of a ferroelectric metal, in which a ferroelectric-like structural transition occurs in the metallic state. Up to now, no clear example of such a material has been identified. Here we report on a centrosymmetric (R3c) to non-centrosymmetric (R3c) transition in metallic LiOsO3 that is structurally equivalent to the ferroelectric transition of LiNbO3 (ref. 3). The transition involves a continuous shift in the mean position of Li(+) ions on cooling below 140 K. Its discovery realizes the scenario described in ref. 2, and establishes a new class of materials whose properties may differ from those of normal metals.

19.
J Ind Microbiol Biotechnol ; 40(12): 1423-32, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24029876

RESUMO

Fructose-1,6-bisphosphatase (FBPase) and fructokinase (ScrK) have important roles in regenerating glucose-6-phosphate in the pentose phosphate pathway (PPP), and thus increasing L-lysine production. This article focuses on the development of L-lysine high-producing strains by heterologous expression of FBPase gene fbp and ScrK gene scrK in C. glutamicum lysC (fbr) with molasses as the sole carbon source. Heterologous expression of fbp and scrK lead to a decrease of residual sugar in fermentation broth, and heterologous expression of scrK prevents the fructose efflux. Heterologous expression of fbp and scrK not only increases significantly the activity of corresponding enzymes but also improves cell growth during growth on molasses. FBPase activities are increased tenfold by heterologous expression of fbp, whereas the FBPase activity is only increase fourfold during co-expression of scrK and fbp. Compared with glucose, the DCW of heterologous expression strains are higher on molasses except co-expression of fbp and scrK strain. In addition, heterologous expression of fbp and scrK can strongly increase the L-lysine production with molasses as the sole carbon source. The highest increase (88.4 %) was observed for C. glutamicum lysC (fbr) pDXW-8-fbp-scrK, but the increase was also significant for C. glutamicum lysC (fbr) pDXW-8-fbp (47.2 %) and C. glutamicum lysC (fbr) pDXW-8-scrK (36.8 %). By-products, such as glycerol and dihydroxyacetone, are decreased by heterologous expression of fbp and scrK, whereas trehalose is only slightly increased. The strategy for enhancing L-lysine production by regeneration of glucose-6-phosphate in PPP may provide a reference to enhance the production of other amino acids during growth on molasses or starch.


Assuntos
Beta vulgaris/química , Proliferação de Células , Corynebacterium glutamicum/crescimento & desenvolvimento , Corynebacterium glutamicum/metabolismo , Lisina/metabolismo , Melaço , Corynebacterium glutamicum/genética , Fermentação , Frutoquinases/genética , Frutoquinases/metabolismo , Frutose/metabolismo , Frutose-Bifosfatase/genética , Frutose-Bifosfatase/metabolismo , Glucose/metabolismo
20.
Inorg Chem ; 52(2): 800-6, 2013 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-23294042

RESUMO

Carbon-for-nitrogen substitution (51 at% at most) was achieved in the antiferromagnetic metallic host material Mn(3)ZnN. The various carbon-doped compounds were studied using synchrotron X-ray diffraction, and their electrical resistivities, specific heats, and degrees of magnetization were measured for temperatures of 2-400 K. The sharp antiferromagnetic-to-paramagnetic transition of the host material at 185 K broadened markedly as the carbon content was increased, and a significant ferromagnetic character was found to coexist with the antiferromagnetism when the carbon concentration exceeded 27 at%. This critical magnetic behavior is likely in part due to the increase in the density of states at the Fermi level and the increase in the distance between neighboring Mn atoms. The exact mechanism responsible for the induction of the complicated magnetic state could not be determined. However, the results demonstrate clearly that the chemical tuning of the X site in antiperovskite Mn(3)AX materials is as useful as that of the A and Mn sites and can be used to develop the properties of these materials for practical applications.

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