Read by QxMD icon Read

Endothermic reactions

Xiao-Shui Li, Yu-Han Fan, Shou-Wen Zhang, Shi-Hua Qi
A novel amino-functionalized magnetic silica (Fe3O4@SiO2-NH2) was easily prepared via a one-step method integrating the immobilization of 3-aminopropyltriethoxysilane with a sol-gel process of tetraethyl orthosilicate into a single process. This showed significant improvement in the adsorption capacity of anionic dyes. The product (Fe3O4@SiO2-NH2) was characterized with scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray spectrometry, zeta potential and vibrating sample magnetometry...
March 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Ming-Chung Yang, Akhilesh Kumar Sharma, W M Chamil Sameera, Keiji Morokuma, Ming-Der Su
The addition reaction of M(Cl)(CO)(PPh3)2 (M = Rh, Ir) and M(PPh3)2 (M = Pd, Pt) fragments with X@C60 (X = 0, Li+) were characterized by density functional theory (DFT) and the artificial force-induced reaction (AFIR) method. The calculated free energy profiles suggested that the η2[6:6]-addition is the most favorable reaction, which is consistent with the experimental observations. In the presence of Li+ ion, the reaction is highly exothermic, leading to η2[6:6] product of L4IrLi+@C60. In contrast, an endothermic reaction was observed in the absence of a Li+ ion...
March 16, 2017: Journal of Physical Chemistry. A
Phuong D Dau, Phuong V Dau, Linfeng Rao, Attila Kovács, John K Gibson
The gas-phase uranyl peroxide dimer, [(UO2)2(O2)(L)2](2+) where L = 2,2'-trifluoroethylazanediyl)bis(N,N'-dimethylacetamide), was synthesized by electrospray ionization of a solution of UO2(2+) and L. Collision-induced dissociation of this dimer resulted in endothermic O atom elimination to give [(UO2)2(O)(L)2](2+), which was found to spontaneously react with water via exothermic hydrolytic chemisorption to yield [(UO2)2(OH)2(L)2](2+). Density functional theory computations of the energies for the gas-phase reactions are in accord with observations...
March 15, 2017: Inorganic Chemistry
Monika Wawrzkiewicz, Przemysław Bartczak, Teofil Jesionowski
A new biomaterial based on chitin and lignin was prepared and applied for the removal of hazardous dye C.I. Direct Blue 71 (DB71) from aqueous solutions and wastewaters. The dye sorption on the chitin/lignin biosorbent (Ch/L) was examined depending on the initial dye concentration (50-200mg/L), phase contact time (1-1440min), kind of auxiliaries (NaCl, Na2SO4, anionic surfactant SDS) and their concentrations (1-20g/L salts, 0.1-0.75g/L SDS), initial solution pH as well as temperature (20-50°C). The equilibrium and kinetic characteristics of DB71 uptake by chitin/lignin followed by the Freundlich isotherm model and the pseudo-second order model rather than the Langmuir, Tempkin models, and pseudo-first order models...
March 7, 2017: International Journal of Biological Macromolecules
Daniel R Fröhlich, Martin M Maiwald, Franziska Taube, Johann Plank, Petra J Panak
The complexation of trivalent lanthanides with a commercial polycarboxylate based concrete superplasticizer (Glenium® 51) is investigated using different spectroscopic techniques. Time-resolved laser fluorescence spectroscopy (TRLFS) in combination with a charge neutralization model is used to determine temperature dependent conditional stability constants (log β'(T)) for the complexation of Eu(iii) with Glenium® 51 in 0.1 mol kg(-1) NaCl solution in the temperature range of 20-90 °C. Only one complex species is observed, and log β'(T) (given in kg per mol eq) shows a very slight increase with temperature from 7...
March 9, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Shaun G Ard, Oscar Martinez, Steven A Brown, Jordan C Sawyer, P B Armentrout, Albert A Viggiano, Nicholas S Shuman
The kinetics of (4)Fe(+)(CO)n=0-2 + O2 are measured under thermal conditions from 300-600 K using a selected-ion flow tube apparatus. Both the bare metal and n = 2 cations are inert to reaction over this temperature range, but (4)Fe(+)(CO) reacts rapidly (k = 3.2 ± 0.8 × 10(-10) cm(3) s(-1) at 300 K, 52% of the collisional rate coefficient) to form FeO(+) + CO2. This is an example of the oxidation of CO by O2 occurring entirely on a single non-noble metal atom. The reaction of the bare metal reaction is known to be endothermic, such that this result is expected; however, the n = 2 reaction has highly exothermic product channels available, such that the lack of reaction is surprising in light of the n = 1 reactivity...
March 9, 2017: Physical Chemistry Chemical Physics: PCCP
Janina Kuduk-Jaworska, Jerzy J Jański, Szczepan Roszak
The results of computational simulation of reaction courses mimicking the transformation of carboplatin from pro-drug into its active shape, responsible for cytotoxic effect, are reported. Implementing the density functional theory (DFT) calculations and the supermolecular approach, we explored the pathways representing two disparate models of carboplatin bioactivation: (1) based on paradigm of carboplatin aquation, and (2) based on new hypothesis that transformation is controlled by electron-transfer processes...
February 11, 2017: Journal of Inorganic Biochemistry
Kate L Henderson, Mingjie Li, Salette Martinez, Edwin A Lewis, Robert P Hausinger, Joseph P Emerson
BACKGROUND: TauD is a nonheme iron(II) and α-ketoglutarate (αKG) dependent dioxygenase, and a member of a broader family of enzymes that oxidatively decarboxylate αKG to succinate and carbon dioxide thereby activating O2 to perform a range of oxidation reactions. However before O2 activation can occur, these enzymes bind both substrate and cofactor in an effective manner. Here the thermodynamics associated with substrate and cofactor binding to FeTauD are explored. METHODS: Thermal denaturation of TauD and its enzyme-taurine, enzyme-αKG, and enzyme-taurine-αKG complexes are explored using circular dichroism (CD) spectroscopy and differential scanning calorimetry (DSC)...
February 15, 2017: Biochimica et Biophysica Acta
M A Ahmed, A A Brick, A A Mohamed
A new approach for removal of indigo carmine blue (IC) dye which is extensively used in jeans manufacture was successfully performed on novel mesoporous [LDH] nanoparticles prepared by sol-gel route using CTAB as shape and pore directing agent. The physicochemical features were monitored by X-ray diffraction (XRD), Fourier transformer infra-red (FTIR), N2 adsorption-desorption isotherm, Field emission electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM). The influence of reaction parameters affecting dye adsorption including contact time, initial dye concentration, pH and temperature were investigated...
May 2017: Chemosphere
Jaruwan Siritapetawee, Chutima Talabnin, Jarunee Vanichtanankul, Chomphunuch Songsiriritthigul, Kanjana Thumanu, Chun-Jung Chen, Nantarat Komanasin
In this study, the binding of a glycosylated serine protease (EuP-82) with human fibrinogen was investigated by the isothermal titration calorimetry (ITC). The ITC analysis indicated that the binding of EuP-82 to fibrinogen in the conditions with or without the activator (Ca(2+) ) was an exothermic reaction (dominant negative enthalpy), which tended to be driven by hydrogen bonding and van der Waals interactions. In contrast, the binding of fibrinogen-EuP-82 in the condition with the inhibitor (Zn(2+) ) was an unfavorable endothermic reaction...
February 1, 2017: Biotechnology and Applied Biochemistry
Weston Thatcher Borden
Thermochemical data are used to show that, of the 89.9 kcal/mol difference between the endothermicity of H2 addition to N2 (ΔH = 47.9 kcal/mol) and the exothermicity of H2 addition to acetylene (ΔH = -42.0 kcal/mol), less than half is due to a stronger π bond in N2 than in acetylene. The other major contributor to the difference of 89.9 kcal/mol between the enthalpies of hydrogenation of N2 and acetylene is that the pair of N-H bonds that are created in the addition of H2 to N2 are significantly weaker than the pair of C-H bonds that are created in the addition of H2 to acetylene...
February 9, 2017: Journal of Physical Chemistry. A
Graham Dawson, Wei Chen, Luhua Lu, Kai Dai
The adsorption properties of two nanomorphologies of trititanate, nanotubes (TiNT) and plates (TiNP), prepared by the hydrothermal reaction of concentrated NaOH with different phases of TiO2, were examined. It was found that the capacity for both morphologies towards methylene blue (MB), an ideal pollutant, was extremely high, with the TiNP having a capacity of 130 mg/g, higher than the TiNT, whose capacity was 120 mg/g at 10 mg/L MB concentration. At capacity, the well-dispersed powders deposit on the floor of the reaction vessel...
January 2017: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Man Wang, Gang Li, Lihui Huang, Jing Xue, Quan Liu, Nan Bao, Ji Huang
Activated carbons were derived from Enteromorpha prolifera immersed in H3PO4 solution or the H3PO4 solution mixed with sodium benzenesulfonate (SBS), producing AC and AC-SBS. NaOH solution was employed in regeneration of ciprofloxacin (CIP)-loaded AC and AC-SBS to obtain RAC and RAC-SBS. The properties of the original and regenerated activated carbons were characterized by thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), N2 adsorption/desorption isotherms and Fourier transform infrared spectroscopy (FTIR)...
January 18, 2017: Ecotoxicology and Environmental Safety
Amartya Roy, Paromita Seal, Jyotirmoy Sikdar, Sanghamitra Banerjee, Rajen Haldar
Linezolid, one of the reserve antibiotic of oxazolidinone class has wide range of antimicrobial activity. Here we have conducted a fundamental study concerning the dynamics of its interaction with bovine serum albumin (BSA), and the post binding modification of the later by employing different spectroscopic (absorption, fluorescence and circular dichroism (CD) spectroscopy) and molecular docking tools. Gradual quenching of the tryptophan (Trp) fluorescence upon addition of linezolid to BSA confirms their interaction...
January 19, 2017: Journal of Biomolecular Structure & Dynamics
Laurean Ilies, Mayuko Isomura, Shin-Ichi Yamauchi, Tomoya Nakamura, Eiichi Nakamura
Upon zincation of two acidic protons attached to the nitrogen and the sp-carbon atoms, a N-protected 2-ethynylaniline cyclizes to a 2,3-dizincioindole at 120 °C. Driven by the energy gain due to formation of two C-Zn bonds, this reaction occurs smoothly without side reactions, although this transformation is intrinsically endothermic in its bare anionic form. The resulting dizinc intermediate can be functionalized with one or two different electrophiles either inter- or intramolecularly on either C(2) or C(3) selectively, depending on the choice of catalyst and the electrophiles...
December 28, 2016: Journal of the American Chemical Society
Bholanath Maity, Debasis Koley
The effect of substituents in disilene mediated N2O activation was studied at the M06-2X/QZVP//ωB97xD/TZVP level of theory. The relationship between structural diversity and the corresponding reactivity of six disilenes (IA-F(t)) in the presence of four different substituents (-NMe2, -Cl, -Me, -SiMe3) is addressed in this investigation. We primarily propose two plausible mechanistic routes: Pathway I featuring disilene → silylene decomposition followed by N2O coordination and Pathway II constituting the N2O attack without Si-Si bond cleavage...
December 20, 2016: Journal of Physical Chemistry. A
Ahmad A Tolba, Said I Mohamady, Shimaa S Hussin, Takaya Akashi, Yuka Sakai, Ahmed A Galhoum, Eric Guibal
The grafting of amino and carboxylic acid groups on cellulose increased La(III) sorption efficiency of cellulose: maximum sorption capacity increased from 38mgLag(-1) for cellulose to 101 and 170mgLag(-1) for amino derivative (PAC) and amino-carboxylic derivative (PCMC). Langmuir equation successfully fits sorption isotherms while uptake kinetics are effectively modeled using the pseudo-first order rate equation (though resistance to intraparticle diffusion plays a significant role in the control of metal recovery)...
February 10, 2017: Carbohydrate Polymers
Qian Gan, Yongyu Qi, Yahong Xiong, Yinlian Fu, Xueyi Le
Two new mononuclear mixed ligand copper(II) complexes [Cu(PBO)(Gly-gly)(H2O)]·ClO4·1.5H2O (1) and [Cu(PBO)(Gly-L-leu)(H2O)]·ClO4 (2) (PBO is 2-(2'-pyridyl)benzoxazole, Gly-gly and Gly-L-leu are Glycyl-glycine anion and Glycyl-L-leucine anion, respectively), have been prepared and characterized by various analytical and spectral techniques. The interactions of the complexes with DNA were investigated using multi-spectroscopic methods (absorption, emission, circular dichroism), viscometry and electrochemical titration as well as molecular docking technique...
December 15, 2016: Journal of Fluorescence
Tahshina Begum, Manoj Mondal, Manash Protim Borpuzari, Rahul Kar, Golap Kalita, Pradip K Gogoi, Utpal Bora
A bis-N-heterocyclic carbene (NHC) functionalized with chloropropyltriethoxysilane over silica was used to synthesize a well-defined immobilized palladium complex. This complex is a suitable and easily retrievable catalyst for Suzuki-Miyaura cross-coupling reactions under mild aqueous conditions. Excellent yields and conversions were obtained with low palladium loadings (down to 0.03 mol% Pd). The catalyst can be reused up to six cycles without the loss of its activity. The catalytic role of the NHC complex of palladium during coupling between bromobenzene and phenylboronic acid was investigated theoretically...
January 3, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
Fatih Gul, Ibrahim Y Orhan, Furkan S Ceylan, Nadir B Akdeniz, H Abdulkadir Karadag
PURPOSE: Temperature sensitivity is found in all multicelleular organisms, as well as in most primitive life forms. The ubiquity of this temperature sensitivity is an indicator of its effects at the multicellular, cellular and molecular levels [1]. Previous studies have shown that temperature-based regulation is present in the transcriptional process [2]. RNA Thermometers, temperature-sensitive sequences, have been shown to act on heat-shock genes to regulate temperature-dependant systems in many organisms [3,4]...
December 1, 2016: Clinical and Investigative Medicine. Médecine Clinique et Experimentale
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"