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排序方式: 共有284条查询结果,搜索用时 15 毫秒
211.
Antonio Proto Ermanno Luciano Carmine Capacchione Oriana Motta 《Macromolecular rapid communications》2002,23(3):183-186
The presence of an organic Lewis base, such as THF, enhances the syndiospecificity of the catalytic system ZrCl4/methylaluminoxane toward the polymerization of styrene. The polymer has low molecular weight and a microstructure similar to other polystyrenes obtained with zirconium‐based catalysts. 相似文献
212.
Santa Anna L. M. Sebastian G. V. Pereira N. Alves T. L. M. Menezes E. P. Freire D. M. G. 《Applied biochemistry and biotechnology》2001,91(1-9):459-467
The Pseudomonas aeruginosa PA1 strain, isolated from the water of oil production in Sergipe, Northeast Brazil, wasevaluated as a potential rhamnolipid
type of biosurfactant producer. The production of biosurfactants was investigated using different carbon sources (n-hexadecane, paraffin oil, glycerol, and babassu oil) and inoculum concentrations (0.0016–0.008 g/L) The best results were
obtained with glycerol as the substrate and an initial cell concentration of 0.004 g/L. AC:N ratio of 22.8 led to the greatest
production of rhamnolipids (1700 mg/L) and efficiency (1.18 g of rhamnolipid/g of dry wt). 相似文献
213.
Antonio Da Settimo Giampaolo Primofiore Federico Da Settimo Francesca Simorini Anna Maria Marini Concettina La Motta Sabrina Taliani 《Journal of heterocyclic chemistry》2000,37(2):373-377
The preparation of a novel purine containing heterocyclic ring system, indolotriazinopurine, by the condensation of 8‐hydrazinotheophylline with 5‐substituted isatins via the intermediate hemiaminal and hydrazone derivatives, is described. 相似文献
214.
Santa Islam S. M. Abu Nayem Ahtisham Anjum Syed Shaheen Shah A. J. Saleh Ahammad Md. Abdul Aziz 《Chemical record (New York, N.Y.)》2024,24(1):e202300017
Aluminum air batteries (AABs) are a desirable option for portable electronic devices and electric vehicles (EVs) due to their high theoretical energy density (8100 Wh K−1), low cost, and high safety compared to state-of-the-art lithium-ion batteries (LIBs). However, numerous unresolved technological and scientific issues are preventing AABs from expanding further. One of the key issues is the catalytic reaction kinetics of the air cathode as the fuel (oxygen) for AAB is reduced there. Additionally, the performance and price of an AAB are directly influenced by an air electrode integrated with an oxygen electrocatalyst, which is thought to be the most crucial element. In this study, we covered the oxygen chemistry of the air cathode as well as a brief discussion of the mechanistic insights of active catalysts and how they catalyze and enhance oxygen chemistry reactions. There is also extensive discussion of research into electrocatalytic materials that outperform Pt/C such as nonprecious metal catalysts, metal oxide, perovskites, metal-organic framework, carbonaceous materials, and their composites. Finally, we provide an overview of the present state, and possible future direction for air cathodes in AABs. 相似文献
215.
Tomofumi Santa Jinli Luo Chang-Kee Lim Kuzuhiro Imai 《Biomedical chromatography : BMC》1998,12(2):73-77
The enantiomneric separation and the detection of 2-arylpropionic acids after derivatization with the fluorescent reagents with a benzofurazan structure, ( S )-(+)-4-( N,N -dimethylaminosulphonyl)-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole (( S )-DBD-Apy), (R)-(-)-4-nitro-7-(3-aminopyrrolidin-1-yl)-2,1,3-benzoxadiazole (( R )-NBD-Apy), 4- N,N -dimethylaminosulphonyl-7-piperazino-2,1,3-benzoxadiazole (DBD-PZ) and N -hydrazinoformylmethyl- N -methylamino-4,4- N,N -dimethylaminosulphonyl-2,1,3-benzoxadiazole (DBD-CO-Hz) by high-performance liquid chromatography (HPLC) and electrospray ionization mass spectrometry (ESI-MS) were examined. The diastereomeric derivatization with ( S )-DBD-Apy or ( R )-NBD-Apy and the separation on the reversed phase column afforded the high sensitivity. The separation on chiral stationary phase after non-chiral derivatization with DBD-PZ or DBD-CO-Hz provided less sensitivity. The signal-to-noise ratio of ( S )-DBD-Apy-( S )-ketoprofen of 200:1 was observed for 12.5 picomole (pmol) injection and selected ion monitoring (SIM) of the quasi-molecular ion after splitting 1:7 before entering into the electrospray ion sources. As a result, the usefulness of these reagents for MS detection has been demonstrated. © 1998 John Wiley & Sons, Ltd. 相似文献
216.
Carlos M. R. De Sant'anna Ricardo Bicca De Alencastro Carlos R. Rodrigues Gabriela Barreiro Eliezer J. Barreiro Joaquim Delphino Da Motta Neto Antnio Carlos C. Freitas 《International journal of quantum chemistry》1996,60(8):1835-1843
In this work, we evaluated structural and electronic similarities between a new class of acylhydrazones, recently presented as effective inhibitors of a Plasmodium falciparum cysteine protease, and a series of pyrazole arylacylhydrazones with analgesic and antiaggregating (antithrombotic) properties, using AM1. The calculated results suggest that at least one of the pyrazole compounds is similar enough to the active compounds to be considered as a candidate for a future antimalarial series. © 1996 John Wiley & Sons, Inc. 相似文献
217.
Maria Clara de Moraes Motta Machado Brbara Morandi Lepaus Patrícia Campos Bernardes Jackline Freitas Brilhante de So Jos 《Molecules (Basel, Switzerland)》2022,27(20)
Chlorinated compounds are usually applied in vegetable sanitization, but there are concerns about their application. Thus, this study aimed to evaluate ultrasound (50 kHz), acetic acid (1000; 2000 mg/L), and peracetic acid (20 mg/L) and their combination as alternative treatments to 200 mg/L sodium dichloroisocyanurate. The overall microbial, physicochemical, and nutritional quality of kale stored at 7 °C were assessed. The impact on Salmonella enterica Typhimurium was verified by plate-counting and scanning electron microscopy. Ultrasound combined with peracetic acid exhibited higher reductions in aerobic mesophiles, molds and yeasts, and coliforms at 35 °C (2.6; 2.4; 2.6 log CFU/g, respectively). Microbial counts remained stable during storage. The highest reduction in Salmonella occurred with the combination of ultrasound and acetic acid at 1000 mg/L and acetic acid at 2000 mg/L (2.8; 3.8 log CFU/g, respectively). No synergistic effect was observed with the combination of treatments. The cellular morphology of the pathogen altered after combinations of ultrasound and acetic acid at 2000 mg/L and peracetic acid. No changes in titratable total acidity, mass loss, vitamin C, or total phenolic compounds occurred. Alternative treatments presented equal to or greater efficacies than chlorinated compounds, so they could potentially be used for the decontamination of kale. 相似文献
218.
Phase‐Contact Engineering in Mono‐ and Bimetallic Cu‐Ni Co‐catalysts for Hydrogen Photocatalytic Materials
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Dr. Mario J. Muñoz‐Batista Dr. Debora Motta Meira Prof. Gerardo Colón Dr. Anna Kubacka Prof. Marcos Fernández‐García 《Angewandte Chemie (International ed. in English)》2018,57(5):1199-1203
Understanding how a photocatalyst modulates its oxidation state, size, and structure during a photocatalytic reaction under operando conditions is strongly limited by the mismatch between (catalyst) volume sampled by light and, to date, the physicochemical techniques and probes employed to study them. A synchrotron micro‐beam X‐ray absorption spectroscopy study together with the computational simulation and analysis (at the X‐ray cell) of the light‐matter interaction occurring in powdered TiO2‐based monometallic Cu, Ni and bimetallic CuNi catalysts for hydrogen production from renewables was carried out. The combined information unveils an unexpected key catalytic role involving the phase contact between the reduced and oxidized non‐noble metal phases in all catalysts and, additionally, reveals the source of the synergistic Cu‐Ni interaction in the bimetallic material. The experimental method is applicable to operando studies of a wide variety of photocatalytic materials. 相似文献
219.
Colt R. Heathman Travis S. Grimes Santa Jansone-Popova Santanu Roy Vyacheslav S. Bryantsev Peter R. Zalupski 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(10):2545-2555
The thermodynamic influence of a pre-organized N-donor group on the coordination of trivalent actinides and lanthanides by an aqueous aminopolycarboxylate complexant has been investigated. The synthesized reagent, N-2-methylpicolinate-ethylenediamine-N,N′,N′-triacetic acid (EDTA-Mpic), resembles ethylenediamine-N,N,N′,N′-tetraacetic acid (EDTA) with a single acetate pendant arm replaced by a 6-carboxypyridin-2-ylmethyl group. The rigid N-donor picolinate functionality has a profound impact on ligand protonation and trivalent f element complexation equilibria, as demonstrated by potentiometric, spectroscopic, and liquid/liquid metal-partitioning studies as well as by molecular dynamics calculations. Relative to diethylenetriamine-N,N,N′,N′′,N′′-pentaacetic acid (DTPA), the ability to preferentially bind trivalent actinides over trivalent lanthanides was moderately lowered due to the presence of the N-(6-carboxypyridin-2-ylmethyl) substituent. The structural modification substantially amplifies the total ligand acidity of EDTA-Mpic. As a result the complexant sustains the metal complexation and efficient An3+/Ln3+ differentiation in aqueous mixtures of unprecedented acidity for this class of reagents. 相似文献
220.
Tushar S. Basu Baul Khrawborlang Nongsiej Augustine Lamin Ka‐Ot Santa Ram Joshi Irn Rojas Len Herbert Hpfl 《应用有机金属化学》2019,33(7)
A series of six new Zn (II) compounds, viz., [Zn(HLASA)2(Py)2] ( 1 ), [Zn(HLMASA)2(Py)2] ( 2 ), [Zn(HLMASA)2(4‐MePy)2] ( 3 ), [Zn(HLCASA)2(4‐MePy)2] ( 4 ), [Zn(HLBASA)2(Py)2] ( 5 ), [Zn(HLBASA)2(4‐MePy)2] ( 6 ) and representative Cu (II) and Cd (II) complexes, viz., [Cu(HLASA)2(Py)2(H2O)] ( 7 ) and [Cd(HLBASA)2(Py)3] ( 8 ) [(HLXASA)? = para‐substituted 5‐[(E)‐2‐(aryl)‐1‐diazenyl]‐2‐hydroxybenzoate with X = H (ASA), Me (MASA), Cl (CASA) or Br (BASA); Py = pyridine; 4‐MePy = 4‐methylpyridine] have been synthesized and characterized by spectroscopic techniques and single‐crystal X‐ray diffraction analysis. The structural characterization of the compounds revealed distorted tetrahedral ( 1 – 6 ), square‐pyramidal ( 7 ) and pentagonal‐bipyramidal ( 8 ) coordination geometries around the metal atom, in which the aryl‐substituted diazosalicylate ligands are coordinated only through the oxygen atoms of carboxylate groups, either in an anisobidentate or isobidentate mode; meanwhile, the 2‐hydroxy groups of the monoanionic ligand (HLXASA)? are involved only in intramolecular O‐H···O hydrogen bonds with the carboxylate function. In the crystal structures of 1 – 8 , the complex molecules are assembled by π‐stacking interactions giving mostly infinite 1D strands. The intermolecular binding in the solid state structures is accomplished by diverse additional non‐covalent contacts including C‐H···O, C‐H···N, C‐H···π, C‐H···Br, O···Br, Br···π and van der Waals contacts. Although the primary and secondary ligands in the Zn (II) complex series 1 – 6 carry different substituents at the periphery (X = H, Me, Cl, Br for (HLXASA)? and R = H, Me for 4‐Py‐R), five of the crystal structures were isostructural. Additionally, the antimicrobial activity of the pro‐ligands H2LXASA and their Zn (II), Cu (II) and Cd (II) compounds were studied in a comparative manner, showing high sensitivity (IZD ≥ 20) against Bacillus subtilis. 相似文献