Relevant bibliographies by topics / Urea – Spectra / Journal articles
To see the other types of publications on this topic, follow the link: Urea – Spectra.

Journal articles on the topic 'Urea – Spectra'

Author: Grafiati
Published: 4 June 2021
Last updated: 16 February 2022

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles

Select a source type:

Consult the top 50 journal articles for your research on the topic 'Urea – Spectra.'

Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.

You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.

Browse journal articles on a wide variety of disciplines and organise your bibliography correctly.

1

Bakibaev, А. А., М. Zh Sadvakassova, V. S. Malkov, R. Sh Еrkasov, A. A. Sorvanov, and O. A. Kotelnikov. "Study of the biologically active acyclic ureas by nuclear magnetic resonance." Bulletin of the Karaganda University. "Chemistry" series 100, no. 4 (2020): 60–74. http://dx.doi.org/10.31489/2020ch4/60-74.

Full text
Abstract:
A wide variety of acyclic ureas comprising alkyl, arylalkyl, acyl, and aryl functional groups are investigated by nuclear magnetic resonance spectroscopy. In general, spectral characteristics of more than 130 substances based on acyclic ureas dissolved in deuterated dimethyl sulfoxide at room temperature are studied. The re-sults obtained based on the studies of 1H and 13C NMR spectra of urea and its N-alkyl-, N-arylalkyl-, N-aryl- and 1,3-diaryl derivatives are presented, and the effect of these functional groups on the chemical shifts in carbonyl and amide moieties in acyclic urea derivative
APA, Harvard, Vancouver, ISO, and other styles
2

Eddy, Christopher V., and Mark A. Arnold. "Near-Infrared Spectroscopy for Measuring Urea in Hemodialysis Fluids." Clinical Chemistry 47, no. 7 (2001): 1279–86. http://dx.doi.org/10.1093/clinchem/47.7.1279.

Full text
Abstract:
Abstract Background: Near-infrared spectroscopy is proposed as a method for providing real-time urea concentrations during hemodialysis treatments. The feasibility of such noninvasive urea measurements is evaluated in undiluted dialysate fluid. Methods: Near-infrared spectra were collected from calibration solutions of urea prepared in dialysate fluid. Spectra were collected over three distinct spectral regions, and partial least-squares calibration models were optimized and compared for each. Selectivity for urea was demonstrated with two-component samples composed of urea and glucose in the
APA, Harvard, Vancouver, ISO, and other styles
3

Olesberg, Jonathon T., Mark A. Arnold, and Michael J. Flanigan. "Online Measurement of Urea Concentration in Spent Dialysate during Hemodialysis." Clinical Chemistry 50, no. 1 (2004): 175–81. http://dx.doi.org/10.1373/clinchem.2003.025569.

Full text
Abstract:
Abstract Background: We describe online optical measurements of urea in the effluent dialysate line during regular hemodialysis treatment of several patients. Monitoring urea removal can provide valuable information about dialysis efficiency. Methods: Spectral measurements were performed with a Fourier-transform infrared spectrometer equipped with a flow-through cell. Spectra were recorded across the 5000–4000 cm−1 (2.0–2.5 μm) wavelength range at 1-min intervals. Savitzky–Golay filtering was used to remove baseline variations attributable to the temperature dependence of the water absorption
APA, Harvard, Vancouver, ISO, and other styles
4

Campbell, Blair F., and Leigh B. Clark. "Polarized vacuum ultraviolet spectra of crystalline urea." Journal of the American Chemical Society 111, no. 21 (1989): 8131–36. http://dx.doi.org/10.1021/ja00203a011.

Full text
APA, Harvard, Vancouver, ISO, and other styles
5

Bakibaev, A. A., S. Yu Panshina, O. V. Ponomarenko, V. S. Malkov, O. A. Kotelnikov, and A. K. Tashenov. "1D and 2D NMR spectroscopy for identification of carbamide-containing biologically active compounds." Bulletin of the Karaganda University. "Chemistry" series 101, no. 1 (2021): 71–81. http://dx.doi.org/10.31489/2021ch1/71-81.

Full text
Abstract:
Urea (carbamide) is the main end product of amino acids' metabolism in mammals. Extensive research in the field of urea chemistryhas contributed to the creation of many biologically active and other compounds based on the carbamide fragment NH–CO–NH. The substituting groups of urea directly affect its properties and characteristics which are reflected in the NMR spectral data and this circumstance can be the basis for the identification of urea derivatives. In this work, chemical shifts in the NMR spectra of urea and its acyclic structure, barbituric series, imidazolidinone series and bicyclic
APA, Harvard, Vancouver, ISO, and other styles
6

Petibois, Cyril, Georges Cazorla, André Cassaigne, and Gérard Déléris. "Plasma Protein Contents Determined by Fourier-Transform Infrared Spectrometry." Clinical Chemistry 47, no. 4 (2001): 730–38. http://dx.doi.org/10.1093/clinchem/47.4.730.

Full text
Abstract:
Abstract Background: Fourier-transform infrared (FT-IR) spectrometry has been used to measure small molecules in plasma. We wished to extend this use to measurement of plasma proteins. Methods: We analyzed plasma proteins, glucose, lactate, and urea in 49 blood samples from 35 healthy subjects and 14 patients. For determining the concentration of each biomolecule, the method used the following steps: (a) The biomolecule was sought for which the correlation between spectral range areas of plasma FT-IR spectra and concentrations determined by comparison method was greatest. (b) The IR absorption
APA, Harvard, Vancouver, ISO, and other styles
7

Jirman, Josef, and Pavel Pech. "17O NMR Spectra of Acylated Ureas and Thioureas." Collection of Czechoslovak Chemical Communications 57, no. 6 (1992): 1278–81. http://dx.doi.org/10.1135/cccc19921278.

Full text
Abstract:
17O NMR spectra of ten acyl- and diacylureas (I-V) and thioureas (VII-X) were measured. 17O NMR chemical shifts of the ureido oxygen in the ureas range from 240 to 310 ppm, those of the acyl oxygens from 377 to 400 ppm (acetyl groups) and 359 to 389 ppm (benzoyl groups), the half-widths being tens to hundreds Hz. Acylation of urea to the diacyl stage has an almost twice as large effect on the chemical shift of the ureido oxygen than has the monoacylation. From the viewpoint of 17O NMR shifts, no significant differences has been found in the influence of ureido and thioureido groups on the tran
APA, Harvard, Vancouver, ISO, and other styles
8

Nyanzi, Steven A., Maureen Isiko, Francis Kateregga, and Wolfgang Schwack. "Second-Derivative Spectrometric Determination of Urea in Milk Using the Diacetyl Monoxime Reagent." Journal of AOAC INTERNATIONAL 93, no. 2 (2010): 485–91. http://dx.doi.org/10.1093/jaoac/93.2.485.

Full text
Abstract:
Abstract The application of derivative spectrometry to resolve overlapping spectra and improve the sensitivity and selectivity of the colorimetric determination of urea in milk using diacetyl monoxime is presented. With first-derivative (1D) spectrometry, the max of the colored complex was established to be 525 nm. The absorption band at max 525 nm in normal absorption (0D) spectrometry was resolved into three clearly distinct spectral bands with minima at 497, 530, and 566 nm with second-derivative (2D) spectrometry. With the second-derivative (2D530) technique, the depth of the trough of the
APA, Harvard, Vancouver, ISO, and other styles
9

Ilczyszyn, M. M., H. Ratajczak, and A. J. Barnes. "Polarized infrared and Raman spectra of urea-phosphoric acid and urea-arsenic acid single crystals." Journal of Raman Spectroscopy 23, no. 1 (1992): 1–13. http://dx.doi.org/10.1002/jrs.1250230102.

Full text
APA, Harvard, Vancouver, ISO, and other styles
10

Zeng, Fan Ming, Chun Li, Hai Lin, Xiao Dong Yang, Dan Wang, and Jing He Liu. "Preparation of Nd:YAG Nanopowders by the Urea Co-Precipitation." Applied Mechanics and Materials 511-512 (February 2014): 78–80. http://dx.doi.org/10.4028/www.scientific.net/amm.511-512.78.

Full text
Abstract:
Nd:YAG nanopowder was prepared by urea co-precipitation method. XRD, TG-DTA, SEM and spectra analysis were utilized to study the properties of the powder. Results indicated that fine Nd:YAG nanopowder can be acquired at 1000°C for 10h. The fluorescence spectra shown that the strongest peak was located at 1061nm, corresponding to the 4F3/24I11/2 energy level transition of Nd3+ ion.
APA, Harvard, Vancouver, ISO, and other styles
11

Heise, H. M., R. Marbach, A. Bittner, and Th Koschinsky. "Clinical Chemistry and near Infrared Spectroscopy: Multicomponent Assay for Human Plasma and its Evaluation for the Determination of Blood Substrates." Journal of Near Infrared Spectroscopy 6, no. 1 (1998): 361–74. http://dx.doi.org/10.1255/jnirs.157.

Full text
Abstract:
A multicomponent assay for the blood substrates of total protein, glucose, total cholesterol, triglycerides and urea in human EDTA-plasma by FT-IR spectroscopy is described. Transmission near infrared spectra of plasma were recorded using a 1 mm cell. Partial least-squares was applied for multivariate calibration taking into account optimising the spectral ranges of absorbance or logarithmised single beam spectra. The standard errors of prediction for the population of 124 plasma samples of different patients calculated by cross-validation are in the range of clinical acceptance for protein, c
APA, Harvard, Vancouver, ISO, and other styles
12

Liu, Peng, Fang Yi Li, Jian Feng Li, Kai Kai Guan, and Gang Li. "Applications of Infrared Spectrometry in Molecular Groups Analysis of Plasticized Starch." Advanced Materials Research 816-817 (September 2013): 1278–81. http://dx.doi.org/10.4028/www.scientific.net/amr.816-817.1278.

Full text
Abstract:
In order to study the recrystallization of the thermoplastic starch, this paper obtained the IR spectra of starch respectively plasticized by urea, glycerin and glycol. By analytical solutions spectra of vibration frequency of molecular groups, the paper studied the destructive effect of starch crystal structure, and plasticizer to form new hydrogen bonds with starch by hydroxyl group bonded. Excessive plasticizer was not suggested. When the ratio of starch and urea was 102, the thermoplastic starch was excellent in thermoplasticity and hot-workability.
APA, Harvard, Vancouver, ISO, and other styles
13

Wu, Gang, Huan Wang, Jiangwei Xiao, et al. "Blocking of matrix metalloproteinases-13 responsive peptide in poly(urethane urea) for potential cartilage tissue engineering applications." Journal of Biomaterials Applications 32, no. 8 (2018): 999–1010. http://dx.doi.org/10.1177/0885328217753414.

Full text
Abstract:
The matching of scaffold degradation rate with neotissue growth is required for tissue engineering applications. Timely provision of proper spaces especially for cartilage tissue engineering plays a pivotal role in chondrocyte cluster formation. In this study, poly(urethane urea) was synthesized using conventional two-stage method by extending the isocyanate group terminated prepolymers with different amounts of GPLGLWARK peptide, which responses the degrading induced by matrix metalloproteinase 13, the main proteinase for cartilage matrix degradation. The Fourier transform infrared spectromet
APA, Harvard, Vancouver, ISO, and other styles
14

Hitchcock, A. P., S. G. Urquhart, H. Ade, E. G. Rightor, and W. Lidy. "Quantitative Chemical Speciation of Multi-Phase Polymers Using Zone Plate x-ray Microscopy." Microscopy and Microanalysis 4, S2 (1998): 808–9. http://dx.doi.org/10.1017/s1431927600024168.

Full text
Abstract:
Phase segregation is important in determining the properties of many complex polymers, including polyurethanes. Achieving a better understanding of the links between formulation, chemical nature of segregated phases, and physical properties, has the potential to aid development of improved polymers. However, the sub-micron size of segregated features precludes detailed chemical analysis by most existing methods. Zone-plate based, scanning transmission X-ray microscopes (STXM) at NSLS and ALS provide quantitative chemical analysis (speciation) of segregated polymer phases at ∼50 nm spatial reso
APA, Harvard, Vancouver, ISO, and other styles
15

Li, Xiaochun, Stephen J. Stotesbury, and Upali A. Jayasooriya. "Infrared spectra of urea isolated in a solid argon matrix." Spectrochimica Acta Part A: Molecular Spectroscopy 43, no. 12 (1987): 1595–97. http://dx.doi.org/10.1016/s0584-8539(87)80054-5.

Full text
APA, Harvard, Vancouver, ISO, and other styles
16

Kaavessina, Mujtahid, Chitra Husnabilqis, and Meylani Tri Hardiyanti. "Smart-Urea-Controlled-Release-Nitrogen-Fertilizer Menggunakan Plastik Biodegradable Poli Asam Laktat Sebagai Carrier." Equilibrium Journal of Chemical Engineering 1, no. 2 (2017): 39. http://dx.doi.org/10.20961/equilibrium.v1i2.40421.

Full text
Abstract:
<p>Poly lactic acid is a polymer that has been developed as an alternative to substitution of conventional polymers. The properties of this polymer are biodegradable in nature and non-toxic substances. These polymers potentially can be used as a matrix for urea carries. The aim of this research was to synthesize poly lactic acid in a low molecular weight. This product can be used as a matrix that urea release controller during the process of fertilization. The methodology consisted of two stages. The first stage was polycondensation of lactic acid and degradability test. Lactic acid was
APA, Harvard, Vancouver, ISO, and other styles
17

Patel, Hasmukh S., and Manhar J. Lad. "Novel Terpolymers: Poly(keto–amine–urea)S." High Performance Polymers 8, no. 2 (1996): 225–31. http://dx.doi.org/10.1088/0954-0083/8/2/004.

Full text
Abstract:
Thermally stable polymers containing keto–amine–urea groups have been prepared by condensation of keto–amino groups containing diamine and various diisocyanates. The resulting polymer samples have been characterized by elemental analysis and IR spectra, and Mn estimated by non-aqueous conductometric titration and thermogravimetry. Curing of commercial epoxy resin-DGEBA by employing these polymers was scanned on a differential scanning colorimeter (DSC). Glass fibre reinforced composites (i.e. laminates) based on such terpolymer–epoxy resin system have also been prepared and characterized.
APA, Harvard, Vancouver, ISO, and other styles
18

Lum, Yip Hing, Azizah Shaaban, Noraiham Mohamad, and Mohd Fairuz Dimin. "Slow Release of Urea Encapsulated by Starch PVA Matrix." Key Engineering Materials 707 (September 2016): 28–31. http://dx.doi.org/10.4028/www.scientific.net/kem.707.28.

Full text
Abstract:
The hydrophobicity of starch/PVA blend was improved by crosslinking with boric acid. It was found that the swelling ratio of the boric acid modified starch/PVA matrix decreased as function of boric acid concentration. FTIR spectra and SEM images demonstrated that the urea had been encapsulated in polymer matrix successfully. The urea release characteristic was explained with respect to the swelling ratio and crosslinking density of polymer matrix. In addition, the matrix displayed a good barrier for controlling the release rate of urea from pellet.
APA, Harvard, Vancouver, ISO, and other styles
19

Jirman, Josef, and Antonín Lyčka. "15N, 13C, and 1H NMR spectra of acylated ureas and thioureas." Collection of Czechoslovak Chemical Communications 52, no. 10 (1987): 2474–81. http://dx.doi.org/10.1135/cccc19872474.

Full text
Abstract:
A series of 1-acylated and 1,3-diacylated (acyl = acetyl or benzoyl) ureas and thioureas have been prepared and their proton-coupled and proton-decoupled 15N, 13C, and 1H NMR spectra have been measured. All the signals have been assigned. The 15N NMR chemical shifts in 1-acylated ureas and thioureas are shifted downfield as compared with δ(15N) of urea and thiourea, resp. This shift is greater for N-1 than for N-3 nitrogen atoms in both the series. When comparing acylureas and acylthioureas it is obvious from the Δδ(15N) differences that the CS group is better than CO group in transferring the
APA, Harvard, Vancouver, ISO, and other styles
20

Haaland, David M. "Synthetic Multivariate Models to Accommodate Unmodeled Interfering Spectral Components during Quantitative Spectral Analyses." Applied Spectroscopy 54, no. 2 (2000): 246–54. http://dx.doi.org/10.1366/0003702001949177.

Full text
Abstract:
The analysis accuracy and precision of any multivariate calibration method will be severely degraded if unmodeled sources of spectral variation are present in the unknown sample spectra. A synthetic method for correcting errors generated by the presence of unmodeled components or other sources of unmodeled spectral variation has been developed. If the spectral shape of the unmodeled spectral component can be obtained and mathematically added in variable amounts to the original calibration spectra, then a new synthetic multivariate calibration model can be generated from the augmented data to a
APA, Harvard, Vancouver, ISO, and other styles
21

Xu, Shimin, and Leigh B. Clark. "Polarized vacuum ultraviolet spectra of crystalline glycoluril: a urea dimerlike molecule." Journal of the American Chemical Society 117, no. 15 (1995): 4379–86. http://dx.doi.org/10.1021/ja00120a021.

Full text
APA, Harvard, Vancouver, ISO, and other styles
22

Durman, R., U. A. Jayasooriya, and S. F. A. Kettle. "LO-TO effects in the single-crystal Raman spectra of urea." Journal of Physical Chemistry 92, no. 3 (1988): 620–22. http://dx.doi.org/10.1021/j100314a010.

Full text
APA, Harvard, Vancouver, ISO, and other styles
23

Bala, Sib Sankar, and Pradip N. Ghosh. "Local mode analysis for the overtone spectra of urea and thiourea." Journal of Molecular Structure 127, no. 3-4 (1985): 277–81. http://dx.doi.org/10.1016/0022-2860(85)80010-7.

Full text
APA, Harvard, Vancouver, ISO, and other styles
24

Langer, Jutta, Bernhard Schrader, Volker Bastian, and Eberhard Jacob. "Infrared spectra and force constants of urea in the gaseous phase." Fresenius' Journal of Analytical Chemistry 352, no. 5 (1995): 489–95. http://dx.doi.org/10.1007/bf00323373.

Full text
APA, Harvard, Vancouver, ISO, and other styles
25

Cai, Shuwei, Hongguo Zhao, Tianxiang Li, et al. "Influence of molecular interplay on the HPAM/UR rheological properties in an aqueous solution." RSC Advances 7, no. 59 (2017): 37055–64. http://dx.doi.org/10.1039/c7ra05263d.

Full text
Abstract:
Herein, the interaction between partially hydrolyzed polyacrylamide (HPAM) and urea (UR) in an aqueous solution was characterizedviadifferential scanning calorimetry (DSC) and two-dimension correlation spectra (2DCOS).
APA, Harvard, Vancouver, ISO, and other styles
26

Tan, Suo Kui, Xiao Ping Song, Hong Yan Guo, Song Ji, and Hong Zhao. "Urea Effect on Strong Electrorheological Response of Novel Core-Shell Nanoparticles." Materials Science Forum 675-677 (February 2011): 311–14. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.311.

Full text
Abstract:
Electrorheological (ER) fluids are regarded as smart materials with potential for application in various industries because of the controllable viscosity, the reversibly and fast response. In this paper, core-shell structured Ni/Ti/Urea nanoparticles, as an ER material, were prepared by a sol-gel method. TEM, XRD and FT-IR spectra demonstrated that the Ni nanoparticles have been homogeneously coated with a 2 nm thick layer of TiO2 containing polar groups. The polar groups were caused by the introduction of urea. The ER effect of the fluids of Ni/Ti/Urea particles in silicone oil was investigat
APA, Harvard, Vancouver, ISO, and other styles
27

Sharma, Mohita, Mohd Saleem, Balgar Singh, H. N. Sheikh, and B. L. Kalsotra. "Preparation and Characterization of Cyano Complexes of Oxotungsten(IV) with Mannich Base Ligands." E-Journal of Chemistry 7, s1 (2010): S231—S238. http://dx.doi.org/10.1155/2010/378561.

Full text
Abstract:
Oxocyanotungsten(IV) complexes, (Ph3P)2NH2[WO(CN)3L–L]. 3H2O and Cs[WO(CN)3L–L].H2O (where L–L = morpholinobenzyl benzamide (MBB), piperidinobenzyl benzamide (PBB), piperidinobenzyl urea (PBU), piperidinobenzyl thiourea (PBTU), morpholinobenzyl urea (MBU) and morpholinobenzyl thiourea (MBTU)) were synthesized. The complexes have been prepared by the reaction of K3Na [WO2(CN)4].6H2O with morpholinobenzyl urea and related ligands in aqueous solution around pH of 7-8. These have been isolated as bis(triphenylphosphine)iminium or cesium salts. The complexes have been characterized by elemental ana
APA, Harvard, Vancouver, ISO, and other styles
28

Wang, Chao, Yu Zhang, Hong Xia Huang, Mao Bin Chen, and Dong Sheng Li. "Solution Conformation of Konjac Glucomannan Single Helix." Advanced Materials Research 197-198 (February 2011): 96–104. http://dx.doi.org/10.4028/www.scientific.net/amr.197-198.96.

Full text
Abstract:
The possibility of the existence of konjac glucomannan (KGM) single helix in dilute solution was discussed finely by ultraviolet-visible spectrophotometer (UV-Vis) with Congo red complex, viscosimetry and circular dichroism (CD). KGM bound to Congo red and the λmaxcharacteristic shifted markedly to longer wavelength (514 nm) in 0.25 M aq NaOH. The shifts of λmaxand intrinsic viscosity were also compared in different mediums, such as different concentrations of KGM, NaOH, urea solutions or temperatures. The results indicated that KGM had an ordered, single-helical conformation in neutral, sligh
APA, Harvard, Vancouver, ISO, and other styles
29

Frost, R. L., T. H. Tran, and J. Kristof. "The structure of an intercalated ordered kaolinite — a Raman microscopy study." Clay Minerals 32, no. 4 (1997): 587–96. http://dx.doi.org/10.1180/claymin.1997.032.4.09.

Full text
Abstract:
AbstractChanges in the molecular structure of a highly ordered kaolinite, intercalated with urea and potassium acetate, have been studied using Raman microscopy. A new Raman band, attributed to the inner surface hydroxyl groups strongly hydrogen bound to the acetate, is observed at 3605 cm-1 for the potassium acetate intercalate with the consequential loss of intensity in the bands at 3652, 3670, 3684 and 3693 cm-1. Remarkable changes in intensity of the Raman spectral bands of the low-frequency region of the kaolinite occurred upon intercalation. In particular, the 144 and 935 cm-1 bands incr
APA, Harvard, Vancouver, ISO, and other styles
30

Hušák, Michal, Bohumil Kratochvíl, Petr Sedmera, et al. "Molecular Structure of cis- and trans-Tergurides." Collection of Czechoslovak Chemical Communications 63, no. 3 (1998): 425–33. http://dx.doi.org/10.1135/cccc19980425.

Full text
Abstract:
Four isomers of terguride, a semisynthetic ergot alkaloid derivative, have been prepared by catalytic hydrogenation of (5R,8S)- and (5S,8S)-lisuride [1,1-diethyl-3-(6-methyl-8-ergolenyl)urea]. Relative stereochemistry of the isomers is based on NMR and CD spectra. Absolute configuration of all the series has been confirmed by the X-ray crystal structure determination of (5R,8S,10S)-terguride 2-bromobenzoate [1,1-diethyl-3-(6-methyl-8-isoergolenyl)urea, cis-dihydrolisuride].
APA, Harvard, Vancouver, ISO, and other styles
31

Marinho, J. Z., F. C. Romeiro, S. C. S. Lemos, et al. "Urea-Based Synthesis of Zinc Oxide Nanostructures at Low Temperature." Journal of Nanomaterials 2012 (2012): 1–7. http://dx.doi.org/10.1155/2012/427172.

Full text
Abstract:
The preparation of nanometer-sized structures of zinc oxide (ZnO) from zinc acetate and urea as raw materials was performed using conventional water bath heating and a microwave hydrothermal (MH) method in an aqueous solution. The oxide formation is controlled by decomposition of the added urea in the sealed autoclave. The influence of urea and the synthesis method on the final product formation are discussed. Broadband photoluminescence (PL) behavior in visible-range spectra was observed with a maximum peak centered in the green region which was attributed to different defects and the structu
APA, Harvard, Vancouver, ISO, and other styles
32

Pelletier, Christine C., James L. Lambert, and Mark Borchert. "Determination of Glucose in Human Aqueous Humor Using Raman Spectroscopy and Designed-Solution Calibration." Applied Spectroscopy 59, no. 8 (2005): 1024–31. http://dx.doi.org/10.1366/0003702054615133.

Full text
Abstract:
Glucose concentrations of in vitro human aqueous humor (HAH) samples from cataract patients were determined using 785 nm Raman spectra and partial least squares (PLS) calibration. PLS models were created from spectra of prepared calibration solutions rather than aqueous humor samples. Spectra were obtained with an excitation energy (100 mW for 150 s), which was higher than can be applied in vivo, to decrease the models' contribution to prediction uncertainty. The solutions contained experimentally designed levels of glucose, bicarbonate, lactate, urea, and ascorbate. Multiplicative signal corr
APA, Harvard, Vancouver, ISO, and other styles
33

Zhang, Cui, Chaohui Gao, Jianshuai Mu, Zhanglei Qiu, and Lianzhi Li. "Spectroscopic Studies on Unfolding Processes of Apo-Neuroglobin Induced by Guanidine Hydrochloride and Urea." BioMed Research International 2013 (2013): 1–7. http://dx.doi.org/10.1155/2013/349542.

Full text
Abstract:
Neuroglobin (Ngb), a recently discovered globin, is predominantly expressed in the brain, retina, and other nerve tissues of vertebrates. The unfolding processes of apo-neuroglobin (apoNgb) induced by guanidine hydrochloride (GdnHCl) and urea were investigated by spectroscopic methods. In the unfolding processes, apoNgb's tertiary structural transition was monitored by the changes of intrinsic fluorescence emission spectra, and its secondary structural transition was measured by the changes of far-ultraviolet circular dichroism (CD) spectra. In addition, 8-anilino-1-naphthalenesulfonic acid (A
APA, Harvard, Vancouver, ISO, and other styles
34

Duan, Jiu Fang, Jian Zhang Li, and Li Ping Zhang. "The Study on a New Wood-Based Carrier of Controlle and Release of Fertilizer." Advanced Materials Research 139-141 (October 2010): 710–13. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.710.

Full text
Abstract:
This study prepared a wood-based hydrogel, which was studied as a fertilizer controlle and release carrier. The wood-based hydrogel was prepared by solution polymerization and whose structure was characterized by FTIR spectra. The water absorbing capacity and urea adsorption capacity were studied. The result shows that: With increasing degree of grafting yield, the water absorption increased at first and decreased afterward. The maximum appear at the glutaraldehyde amount of 0.4 times. The urea adsorption of the wood-base hydrogel has a strongest value in 10% aqueous solution of urea. The drug
APA, Harvard, Vancouver, ISO, and other styles
35

RAO, M. V. R., M. ATREYI, and M. R. RAJESWARI. "FLUORESCENCE SPECTRA OF LYSOZYME EXCITED AT 305 NM IN PRESENCE OF UREA." International Journal of Peptide and Protein Research 17, no. 2 (2009): 205–10. http://dx.doi.org/10.1111/j.1399-3011.1981.tb01983.x.

Full text
APA, Harvard, Vancouver, ISO, and other styles
36

Lyashchenko, A. K., V. S. Dunyashev, and A. Yu Zasetsky. "Effects of concentration on the microwave dielectric spectra of aqueous urea solutions." Russian Journal of Physical Chemistry A 91, no. 5 (2017): 887–93. http://dx.doi.org/10.1134/s0036024417050168.

Full text
APA, Harvard, Vancouver, ISO, and other styles
37

Wang, Chao, Zhongzhou Chen, Xia Hong та ін. "The structural basis of urea-induced protein unfolding in β-catenin". Acta Crystallographica Section D Biological Crystallography 70, № 11 (2014): 2840–47. http://dx.doi.org/10.1107/s1399004714018094.

Full text
Abstract:
Although urea and guanidine hydrochloride are commonly used to denature proteins, the molecular underpinnings of this process have remained unclear for a century. To address this question, crystal structures of β-catenin were determined at various urea concentrations. These structures contained at least 105 unique positions that were occupied by urea molecules, each of which interacted with the protein primarilyviahydrogen bonds. Hydrogen-bond competition experiments showed that the denaturing effects of urea were neutralized when polyethylene glycol was added to the solution. These data sugge
APA, Harvard, Vancouver, ISO, and other styles
38

Wang, Hsiaoling, Chao Wang, Charles K. Mann, and Thomas J. Vickers. "Effect of the Water Spectrum on the Determination of Dissolved Ammonia, Urea, and Chloride Concentrations by Raman Spectroscopy." Applied Spectroscopy 52, no. 2 (1998): 240–49. http://dx.doi.org/10.1366/0003702981943301.

Full text
Abstract:
The effect of large, changing concentrations of electrolytes on the behavior of the OH stretching band of water have been investigated with the aim of developing methods for compensating for spectral interferences when solute NH bands are made the basis for mixture analyses. With the use of urea and ammonium salts as analytes, it was found that changing electrolyte concentrations affect the shape of the water band but do not appreciably affect the shapes of either the ammonium ion or urea Raman lines. Chlorides, nitrates, and mixtures of these were used as electrolytes. The identity of the ani
APA, Harvard, Vancouver, ISO, and other styles
39

Belloche, A., R. T. Garrod, H. S. P. Müller, et al. "Re-exploring Molecular Complexity with ALMA (ReMoCA): interstellar detection of urea." Astronomy & Astrophysics 628 (July 26, 2019): A10. http://dx.doi.org/10.1051/0004-6361/201935428.

Full text
Abstract:
Context. Urea, NH2C(O)NH2, is a molecule of great importance in organic chemistry and biology. Two searches for urea in the interstellar medium have been reported in the past, but neither were conclusive. Aims. We want to take advantage of the increased sensitivity and angular resolution provided by the Atacama Large Millimeter/submillimeter Array (ALMA) to search for urea toward the hot molecular cores embedded in the high-mass-star-forming region Sgr B2(N). Methods. We used the new spectral line survey named ReMoCA (Re-exploring Molecular Complexity with ALMA) that was performed toward Sgr B
APA, Harvard, Vancouver, ISO, and other styles
40

Абдуллин, Х. А., А. Е. Кемельбекова, В. М. Лисицын, Д. М. Мухамедшина, Р. Р. Немкаева та А. Т. Тулегенова. "Аэрозольный синтез высокодисперсного люминофора Y-=SUB=-3-=/SUB=-Al-=SUB=-5-=/SUB=-O-=SUB=-12-=/SUB=- : Ce-=SUP=-3+-=/SUP=- с интенсивной фотолюминесценцией". Физика твердого тела 61, № 10 (2019): 1884. http://dx.doi.org/10.21883/ftt.2019.10.48265.501.

Full text
Abstract:
AbstractA simple method of pyrolysis of an aerosol solution of yttrium, aluminum, and cerium nitrates with the addition of urea or citric acid, followed by brief annealing, is developed to obtain a highly dispersed aluminum–yttrium garnet powder that demonstrates intense photoluminescence in the visible light region. Characterization of the synthesized samples (photoluminescence spectra, X-ray diffraction analysis, Raman spectra) showed that intense photoluminescence is achieved only in a narrow window of process conditions, namely, the concentration of nitrate solution and the concentration o
APA, Harvard, Vancouver, ISO, and other styles
41

Malik, Ashraf, Shadma Parveen, Tansir Ahamad, Saad M. Alshehri, Prabal Kumar Singh, and Nahid Nishat. "Coordination Polymer: Synthesis, Spectral Characterization and Thermal Behaviour of Starch-Urea Based Biodegradable Polymer and Its Polymer Metal Complexes." Bioinorganic Chemistry and Applications 2010 (2010): 1–8. http://dx.doi.org/10.1155/2010/848130.

Full text
Abstract:
A starch-urea-based biodegradable coordination polymer modified by transition metal Mn(II), Co(II), Ni(II), Cu(II), and Zn(II) was prepared by polycondensation of starch and urea. All the synthesized polymeric compounds were characterized by Fourier transform-infrared spectroscopy (FT-IR),H-NMRspectroscopy,C-NMRspectroscopy, UV-visible spectra, magnetic moment measurements, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The results of electronic spectra and magnetic moment measurements indicate that Mn(II), Co(II), and Ni(II) complexes show octahedral geometry,
APA, Harvard, Vancouver, ISO, and other styles
42

Qu, Jianan Y., and Lan Shao. "Multiple Band-Pass Filtering Method for Improvement on Prediction Accuracy of Linear Multivariate Analysis." Applied Spectroscopy 55, no. 10 (2001): 1414–21. http://dx.doi.org/10.1366/0003702011953568.

Full text
Abstract:
An approach coupling signal processing and partial least-squares regression analysis (PLS) is described in which raw spectral data are processed with a multiple band-pass filter and the filtered spectra are used in a PLS to build a calibration model for the analyte of interest. The multiple band-pass filter is specifically designed for a desired analyte based on the Fourier frequency characteristics of the pure spectrum of the desired analyte and the spectra of the interference background. It maximizes the ratio of signal to background. This combined multiple band-pass filtering and PLS method
APA, Harvard, Vancouver, ISO, and other styles
43

Kuda-Malwathumullage, Chamathca PS, and Gary W. Small. "Determination of temperatures of aqueous-based samples directly from near infrared spectra." Journal of Near Infrared Spectroscopy 25, no. 5 (2017): 289–300. http://dx.doi.org/10.1177/0967033517731420.

Full text
Abstract:
The temperature sensitivity of underlying water absorption bands can lead to baseline artifacts or apparent spectral band shifts in near infrared spectra and can negatively impact multivariate calibration models used in quantitative analyses. To address this issue, efforts can be made to suppress the temperature-induced spectral variation or knowledge of the temperature can be used to adjust the calibration. To facilitate the latter approach, we explored the ability to estimate the aqueous temperature of the sample directly from the combination region of the near infrared spectrum. This temper
APA, Harvard, Vancouver, ISO, and other styles
44

Wei, Jiyong, Baibiao Huang, Peng Wang, et al. "Photocatalytic Properties of Nitrogen-Doped Bi12TiO20Synthesized by Urea Addition Sol-Gel Method." International Journal of Photoenergy 2012 (2012): 1–8. http://dx.doi.org/10.1155/2012/135132.

Full text
Abstract:
Undoped and nitrogen-doped Bi12TiO20materials were synthesized by urea addition sol-gel method. By adding urea, undoped, and N-doped gel-type precursors were synthesized by low-temperature dehydrolyzation. Nitrogen-doped and undoped nanocrystalline Bi12TiO20were prepared by annealing at 600∘C for 30 minutes. From UV-Vis absorption and diffuse reflection spectrum, the absorbing band shifted from 420 to 500 nm by nitrogen doping. The bonds of Ti–N and N–O were identified by XPS spectra from the prepared materials, and the enhancement of visible light absorption was attributed to nitrogen's subst
APA, Harvard, Vancouver, ISO, and other styles
45

Abidov, Amir, Bunyod Allabergenov, Fei Yi Xiao, et al. "Fabrication and Characterization of Amine Compounds Synthesized from Carbon Dioxide and Ammonia Water Using Transition Metal Doped TiO2." Applied Mechanics and Materials 764-765 (May 2015): 47–50. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.47.

Full text
Abstract:
Capture and reforming fume gases from atmosphere became an ultimate task recently. Photocatalytic reduction to useful compounds is a key to the future. Photoinduced reduction of carbon dioxide and ammonia aqueous solution into amine compounds at room temperature and atmospheric pressure using transition metal doped titanium dioxide is reported in this paper. UV-visible spectra showed a high absorbance at 200 nm wavelength which is a characteristic of urea. High Performance Liquid Chromatography revealed presence of amine compounds and urea was found a main product of photocatalytic reaction.
APA, Harvard, Vancouver, ISO, and other styles
46

Hu, Ya Wei, Hui Rong He, and Yang Min Ma. "Hydrothermal Synthesis, Photoluminescence Property and Superhydrophobicity of In(OH)3." Advanced Materials Research 412 (November 2011): 163–66. http://dx.doi.org/10.4028/www.scientific.net/amr.412.163.

Full text
Abstract:
In this work, we fabricated indium hydroxide (In (OH)3) nanocubes from In (NO3)3 and urea through hydrothermal method. NH4OH form the hydrolysis of urea acts as the OH¯ provider. The resultant products were characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), photoluminescence (PL) spectra and contact angle meter. It was observed that the In (OH)3 nanocubes showed superhydrophobicity with water contact angle 161.9° after modified with fluoroalkylsilane (FAS, CF3(CF2)7CH2CH2Si (OCH3)3), and exhibited PL peak at about 529 nm, corresponding to the deep level emission.
APA, Harvard, Vancouver, ISO, and other styles
47

Nemson, Jeff A., and Anastasios Melis. "Light-Induced Oxidation-Reduction Reactions of Photosystem II in Dichlorophenyl-dimethyl Urea (DCM U) Inhibited Thylakoids." Zeitschrift für Naturforschung C 45, no. 3-4 (1990): 258–64. http://dx.doi.org/10.1515/znc-1990-3-420.

Full text
Abstract:
Abstract Illumination of thylakoid membranes in the presence of 3-(3′,4′-dichlorophenyl)-1,1-dimethyl urea (DCMU) causes the reduction of the primary quinone acceptor QA of photosystem II (PS II) and the storage of a positive charge on the donor side of the photochemical reaction center. These oxidation-reduction reactions are accompanied by characteristic changes of absorbance in the ultra-violet region of the spectrum. The PS II-related absorbance difference spectra (250 -350 nm) were compared in control and hydroxylamine-treated thylakoid membranes, and in thylakoids suspended in the presen
APA, Harvard, Vancouver, ISO, and other styles
48

Liu, Haiyan, Xufeng Meng, Lihui Zhang, and Anqiang Jia. "Urothermal Syntheses, Crystal Structures, and Luminescent Properties of Two New ZnII Compounds Constructed by the Mixed Ligands of 1,2,4-Triazole and 1,4-Naphthalenedicarboxylic Acid or 2,6-Naphthalenedicarboxylic Acid." Australian Journal of Chemistry 68, no. 8 (2015): 1299. http://dx.doi.org/10.1071/ch14669.

Full text
Abstract:
Under urothermal conditions, the self-assembly of ZnII ions, 1,2,3-triazole, and two isomeric dicarboxylate ligands (1,4-H2ndc and 2,6-H2ndc) afforded two new metal–organic frameworks, namely [Zn(1,4-ndc)0.5(taz)]n·n(e-urea) (1) and [Zn(2,6-ndc)0.5(taz)]n·n(H2O)·n(e-urea) (2) (1,4-H2ndc = 1,4-naphthalenedicarboxylic acid; 2,6-H2ndc = 2,6-naphthalenedicarboxylic acid; Htaz = 1,2,4-triazole; e-urea = ethyleneurea), which were further determined by single-crystal X-ray diffraction analyses, elemental analyses, powder X-ray diffraction analyses, and IR spectra. Compound 1 features a 3D pillar-laye
APA, Harvard, Vancouver, ISO, and other styles
49

Shaw, R. Anthony, Steven Kotowich, Michael Leroux, and Henry H. Mantsch. "Multianalyte Serum Analysis Using Mid-Infrared Spectroscopy." Annals of Clinical Biochemistry: International Journal of Laboratory Medicine 35, no. 5 (1998): 624–32. http://dx.doi.org/10.1177/000456329803500505.

Full text
Abstract:
This study assesses the potential for using mid-infrared (mid-IR) spectroscopy of dried serum films as the basis for the simultaneous quantitation of eight serum analytes: Total protein, albumin, triglycerides, cholesterol, glucose, urea, creatinine and uric acid. Infrared transmission spectra were acquired for 300 serum samples, each analysed independently using accepted reference clinical chemical methods. Quantitation methods were based upon the infrared spectra and reference analyses for 200 specimens, and the models validated using the remaining 100 samples. Standard errors in the IR-pred
APA, Harvard, Vancouver, ISO, and other styles
50

Lyman, D. J., and L. A. Gower. "Effect of infrared salt crystals on the spectra of copolyether-urethane-urea films." Vibrational Spectroscopy 9, no. 2 (1995): 203–7. http://dx.doi.org/10.1016/0924-2031(95)00008-i.

Full text
APA, Harvard, Vancouver, ISO, and other styles
We offer discounts on all premium plans for authors whose works are included in thematic literature selections. Contact us to get a unique promo code!

To the bibliography