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Irradiation Conditions (irradiation + condition)
Kinds of Irradiation Conditions Selected AbstractsInfluence of Side-Chain Structure and Irradiation Condition on Photoalignment of Ladder-Like Polysiloxane Films,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2005H.-W. Gu Abstract In this paper we consider the photo-induced aligning capability of various ladder-like polysiloxane-based photoalignment films,which could be used in liquid-crystal displays,bearing different photoreactive side chains, i.e., laterally grafted cinnamate/azobenzene-based dual photoreactive side chains with a short or longer spacer, and terminally fixed coumarin-containing side chains. Results from polarized optical microscopy (POM), Fourier-transform infrared (FTIR) spectroscopy, surface-enhanced Raman scattering (SERS), atomic force microscopy (AFM), etc., are integrated to elucidate the influence of side-chain structure and the irradiation conditions on the photoalignment of ladder-like polysiloxane films. It is demonstrated that the film containing the dual photoreactive group with a longer spacer exhibits better alignment properties. Reasonably, the concerted photoreactions of the dual photoreactive group and the longer spacer are beneficial to the cooperative motion of chromophores at the "domain level", resulting in improved alignment facility and stability. The complicated effects of irradiation conditions and moderate annealing are also discussed. High-quality alignment of the polysilsesquioxane (LPS)-based photoalignment film LPS-CA11 with a longer spacer between the LPS main chain and cinnamoyl/azobenzene side chains can be achieved only within an optimal range of exposure (5,8,J,cm,2), while the pretilt angles can be adjusted in the range 0.5°,7° by varying the incident light intensity. Additionally, moderate annealing before and after illumination can markedly improve the alignment uniformity by self-healing of defects. [source] 4- exo - dig Cyclocarbopalladation: A Straightforward Synthesis of Cyclobutanediols from Acyclic ,-Bromopropargylic Diols under Microwave Irradiation Conditions,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2006Christophe Bour Abstract Treatment of acyclic ,-bromopropargylic diols with tributylstannylated alkynes under palladium catalysis and microwave irradiation conditions gives high yields of the bis(alkylidene)cyclobutanediol derivatives and cyclobutenediols through an efficient 4- exo - dig cyclocarbopalladation. The cyclization is general with a wide variety of alkyne derivatives and gives access to new cyclobutane ring systems bearing one exocyclic double bond and one eneyne substituent as well as bicyclic dienes sharing a common double bond that may be of interest for further elaborations of complex molecules. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] ChemInform Abstract: An Efficient and Greener Approach to the Synthesis of 3,5-Dicyanopyridin-2(1H)-one Derivatives in Aqueous Media under Microwave Irradiation Conditions.CHEMINFORM, Issue 4 2008Runhong Jia Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] A Simple and Efficient Method for the Synthesis of Novel Trifluoromethyl Benzimidazoles under Microwave Irradiation Conditions.CHEMINFORM, Issue 47 2002G. Venkat Reddy Abstract For Abstract see ChemInform Abstract in Full Text. [source] The Synthesis of 1-Arylseleno-3-alkoxy-2-propanols under Microwave Irradiation Conditions.CHEMINFORM, Issue 44 2002Jin-Xian Wang No abstract is available for this article. [source] ChemInform Abstract: Copper-Catalyzed Cross-Coupling Reaction under Microwave Irradiation Conditions.CHEMINFORM, Issue 17 2001Jin-Xian Wang Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Characterization of Portland cements by X-ray spectrometry allied to chemometricsJOURNAL OF CHEMOMETRICS, Issue 11-12 2006Karen Goraieb Abstract This work reports the use of X-ray spectrometry (XRS) allied to chemometric techniques to easily distinguish types of Portland cements, as well as to quantify some of their constituent elements. The samples were irradiated as powders for 200,s using two distinct irradiation conditions, one more adequate for heavier elements (condition 1) and the other (condition 2) for lighter elements, using a conventional bench top energy dispersive X-ray fluorescence (EDXRF) equipment. The spectra were processed via the software The Unscrambler, version 9.2. The PLS 1 LV1,×,LV2 scores graph shows a classification into five groups, in accordance with the calcium concentration, using condition 2. The classification of the cements by producer was feasible using the PLS1 LV1,×,LV3 scores graph, with condition 1. The elements Ca, Si, Al and Mg were successfully quantified using multivariate calibration of the whole spectra. However, for Fe, S and K, better results were obtained by correlating their corresponding K, peaks with concentrations in a univariate procedure, using irradiation condition 2. Chemometric tools allied to XRS are powerful techniques to classify Portland cements, regarding to their origins and their calcium concentration, which is related to the cement type. The PLS chemometric tool was very useful to easily quantify light elements, such as Al, Si and Mg, a challenge in most X-ray analytical methods, since their K, emission peaks are very close to each other. Copyright © 2007 John Wiley & Sons, Ltd. [source] 4- exo - dig Cyclocarbopalladation: A Straightforward Synthesis of Cyclobutanediols from Acyclic ,-Bromopropargylic Diols under Microwave Irradiation Conditions,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2006Christophe Bour Abstract Treatment of acyclic ,-bromopropargylic diols with tributylstannylated alkynes under palladium catalysis and microwave irradiation conditions gives high yields of the bis(alkylidene)cyclobutanediol derivatives and cyclobutenediols through an efficient 4- exo - dig cyclocarbopalladation. The cyclization is general with a wide variety of alkyne derivatives and gives access to new cyclobutane ring systems bearing one exocyclic double bond and one eneyne substituent as well as bicyclic dienes sharing a common double bond that may be of interest for further elaborations of complex molecules. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Reversibly Light-Switchable Wettability of Hybrid Organic/Inorganic Surfaces With Dual Micro-/Nanoscale RoughnessADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Gianvito Caputo Abstract Here, an approach to realize "smart" solid substrates that can convert their wetting behavior between extreme states under selective light irradiation conditions is described. Hybrid organic/inorganic surfaces are engineered by exploiting photolithographically tailored SU-8 polymer patterns as templates for accommodating closely packed arrays of colloidal anatase TiO2 nanorods, which are able to respond to UV light by reversibly changing their surface chemistry. The TiO2 -covered SU-8 substrates are characterized by a dual micro-/nanoscale roughness, arising from the overlapping of surfactant-capped inorganic nanorods onto micrometer-sized polymer pillars. Such combined architectural and chemical surface design enables the achievement of UV-driven reversible transitions from a highly hydrophobic to a highly hydrophilic condition, with excursions in water contact angle values larger than 100°. The influence of the geometric and compositional parameters of the hybrid surfaces on their wettability behavior is examined and discussed within the frame of the available theoretical models. [source] Influence of Side-Chain Structure and Irradiation Condition on Photoalignment of Ladder-Like Polysiloxane Films,ADVANCED FUNCTIONAL MATERIALS, Issue 1 2005H.-W. Gu Abstract In this paper we consider the photo-induced aligning capability of various ladder-like polysiloxane-based photoalignment films,which could be used in liquid-crystal displays,bearing different photoreactive side chains, i.e., laterally grafted cinnamate/azobenzene-based dual photoreactive side chains with a short or longer spacer, and terminally fixed coumarin-containing side chains. Results from polarized optical microscopy (POM), Fourier-transform infrared (FTIR) spectroscopy, surface-enhanced Raman scattering (SERS), atomic force microscopy (AFM), etc., are integrated to elucidate the influence of side-chain structure and the irradiation conditions on the photoalignment of ladder-like polysiloxane films. It is demonstrated that the film containing the dual photoreactive group with a longer spacer exhibits better alignment properties. Reasonably, the concerted photoreactions of the dual photoreactive group and the longer spacer are beneficial to the cooperative motion of chromophores at the "domain level", resulting in improved alignment facility and stability. The complicated effects of irradiation conditions and moderate annealing are also discussed. High-quality alignment of the polysilsesquioxane (LPS)-based photoalignment film LPS-CA11 with a longer spacer between the LPS main chain and cinnamoyl/azobenzene side chains can be achieved only within an optimal range of exposure (5,8,J,cm,2), while the pretilt angles can be adjusted in the range 0.5°,7° by varying the incident light intensity. Additionally, moderate annealing before and after illumination can markedly improve the alignment uniformity by self-healing of defects. [source] The Effect of Seed Vernalization and Irradiation on Growth and Photosynthesis of Field Bean Plants (Vicia faba L. minor) and on Nitrogenase Activity of Root NodulesJOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2000W. Filek The effect of seed vernalization (2,3°C; 36 days) and irradiation intensity during vegetation of field bean upon growth and maximum leaf photosynthesis (Pmax) as well as specific (SNA) and total nitrogenase activity (TNA) of root nodules was investigated. The measurements were performed at the initial stage of pod development of varieties with undetermined (cv. Nadwi,a,ski) and determined (cv. Tibo) growth habit. In comparison with plants in shading, those which grew in full irradiation produced larger leaf area and more dry weight, achieving higher Pmax values. Stimulation of leaf area enlargement and dry weight increase, especially in respect to the dry weight of underground parts had a positive and significant effect upon TNA value. Accumulation of dry weight was higher in vernalized than non-vernalized plants, but only in the case of cv. Nadwi,la,ski, in full irradiation conditions. In the case of plants grown in poorer irradiation conditions TNA values were about 68 % (cv. Nadwi,la,ski) and 54 % (cv. Tibo) lower, due to significant limitation of root nodules. TNA value of vernalized cv. Nadwi,la,ski plants was 66 % higher in comparison with non-vernalized plants. However, the effect was visible only in full irradiation conditions, due to simultaneous greater intensity of root nodules production and higher SNA value. A positive effect of vernalization could also be observed in the decrease of a negative correlation between dry weight of root nodules and SNA in both varieties. Zusammenfassung Der Einfluss der Samenvernalisation (3,3°C; 36 Tage) und der Strahlungsintensität während der Vegetation von Fababohnen hinsichtlich des Wachstums und der maximalen Blattfotosynthese (Pmax) sowie der spezifischen (SNA) und Gesamtnitrogenaseaktivität (TNA) der Wurzelknöllchen wurde untersucht. Die Messungen wurden im ersten Stadium der Hülsenentwicklung an Sorten mit undeterminierten (cv. Nadwi,la,ski) und determinierten (cv. Tibo) Wachstumsstrukturen durchgeführt. Ein Vergleich von Pflanzen unter Beschattung mit Pflanzen unter voller Strahlung zeigte, dass beschattete Pflanzen eine gröiere Blattfläche und höheres Trockengewicht produzierten und damit höhere Pmax -Werte erreichten. Stimulation der Blattflächenvergröierung und der Trockenge wichtszunahme, insbesondere im Hinblick auf die Trockengewichte der unterirdischen Pflanzenteile hatte eine positive und signifikante Auswirkung auf den DNA-Wert. Die Akkumulation von Trockenmasse war in vernalisierten Pflanzen höher als in nicht vernalisierten; dies gilt nur für Sorte Nadwi,la,ski unter dem Einfluss voller Strahlung. Im Fall der Pflanzen, die unter geringer Strahlung wuchsen, waren die TNA-Werte ca. 68 % (cv.Nadwi,la,ski) und 54 % (cv. Tibo) geringer als Folge einer signifikanten Begrenzung des Wurzelknöllchenwachstums. TNA-Werte vernalisierter cv. Nadwi,la,ski-Pflanzen waren um 66 % höher im Vergleich mit nicht vernalisierten Pflanzen. Allerdings zeigte sich diese Wirkung nur unter voller Strahlung als Folge einer vergleichsweise gröieren Intensität der Wurzelknöllchenproduktion und höherer SNA-Werte. Der positive Effekt der Vernalisation konnte ebenfalls beobachtet werden bei einer Abnahme der negativen Korrelation zwischen dem Trockengewicht der Wurzelknöllchen und SNA in beiden Sorten. [source] Simultaneous radiation grafting of vinylbenzyl chloride onto poly(tetrafluoroethylene- co -hexafluoropropylene) filmsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 5 2009Junhwa Shin Abstract In this study, we demonstrated that vinylbenzyl chloride (VBC), a versatile monomer with reactive a chloromethyl group could be grafted onto a poly(tetrafluoroethylene- co -hexafluoropropylene) (FEP) film without a degradation of the chloromethyl group during a simultaneous irradiation process. The effects of various irradiation conditions such as the total dose, dose rate, solvent, and VBC concentration on the degree of grafting of VBC onto a FEP film were also investigated. The prepared PVBC-grafted films were characterized using FTIR, TGA, and SEM EDX. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 [source] Characterization of Portland cements by X-ray spectrometry allied to chemometricsJOURNAL OF CHEMOMETRICS, Issue 11-12 2006Karen Goraieb Abstract This work reports the use of X-ray spectrometry (XRS) allied to chemometric techniques to easily distinguish types of Portland cements, as well as to quantify some of their constituent elements. The samples were irradiated as powders for 200,s using two distinct irradiation conditions, one more adequate for heavier elements (condition 1) and the other (condition 2) for lighter elements, using a conventional bench top energy dispersive X-ray fluorescence (EDXRF) equipment. The spectra were processed via the software The Unscrambler, version 9.2. The PLS 1 LV1,×,LV2 scores graph shows a classification into five groups, in accordance with the calcium concentration, using condition 2. The classification of the cements by producer was feasible using the PLS1 LV1,×,LV3 scores graph, with condition 1. The elements Ca, Si, Al and Mg were successfully quantified using multivariate calibration of the whole spectra. However, for Fe, S and K, better results were obtained by correlating their corresponding K, peaks with concentrations in a univariate procedure, using irradiation condition 2. Chemometric tools allied to XRS are powerful techniques to classify Portland cements, regarding to their origins and their calcium concentration, which is related to the cement type. The PLS chemometric tool was very useful to easily quantify light elements, such as Al, Si and Mg, a challenge in most X-ray analytical methods, since their K, emission peaks are very close to each other. Copyright © 2007 John Wiley & Sons, Ltd. [source] Photobleaching, light-induced discolouration in red peppersJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2006Ji Won Jung Abstract Red peppers dried in sunlight experience surface bleaching, centred near the calyx, on the face exposed to the light. In this study, bleaching mechanisms were studied under simulated irradiation conditions by placing pericarp discs in 2-(N -morpholino) ethane sulfonic acid (MES) and sucrose solution. The moisture content near the calyx of the pepper decreased more slowly than that on the apex side. In addition, pericarp discs incubated without MES/sucrose solution retained more carotenoids than those incubated with solution after 27 h of light treatment. Carotenoids in pericarp discs exposed to the light decreased rapidly over the incubation time, whereas in the dark they decreased slowly and remained higher in content. Changes in malondialdehyde (MDA) level and electrolyte leakage were not observed for pericarp incubation in the dark. A sharp increase in the level of MDA and a change in electrolyte leakage from discs exposed to the light occurred when carotenoids were exhausted. Carotenoid degradation was markedly suppressed by the addition of ascorbic acid. These results demonstrate that carotenoids in red pepper pericarp played a role in protecting cells and were subsequently degraded under intense light conditions. Copyright © 2006 Society of Chemical Industry [source] Bactericidal effect of a 405-nm diode laser on Porphyromonas gingivalisLASER PHYSICS LETTERS, Issue 5 2009Y. Kotoku Abstract The study was conducted to determine the effect of 405-nm diode laser irradiation on periodontopathic bacteria such as Porphyromonas gingivalis in vitro. A diluted suspension of P. gingivalis was irradiated directly with a 405-nm diode laser under conditions of 100 mW-10 sec, 100 mW-20 sec, 200 mW-5 sec, 200 mW-10 sec, 200 mW-20 sec, 400 mW-5 sec, 400 mW-10 sec, and 400 mW-20 sec. The energy density ranged from 2.0 to 16.0 J/cm2. The irradiated bacterial suspension was spread on a blood agar plate and growth of the colonies was examined after an anaerobic culture for 7 days. Bacterial growth was inhibited under all irradiation conditions, but the bactericidal effect of the 405-nm diode laser depended on the energy density. More than 97% of bacterial growth was inhibited with irradiation at an energy density > 4.0 J/cm2. The mechanism of the bactericidal effect is photochemical, rather than photothermal. These findings suggest that a 405-nm diode laser has a high bactericidal effect on P. gingivalis. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Microwave-Assisted Dimroth Rearrangement of Thiazines to Dihydropyrimidinethiones: Synthetic and Mechanistic AspectsMOLECULAR INFORMATICS, Issue 5-6 2006Abstract The Dimroth rearrangement of a set of substituted 2-amino-6H -1,3-thiazines into 3,4-dihydropyrimidine-2-thiones was investigated. The rearrangements were carried out under microwave irradiation conditions in batch or continuous flow format, employing either toluene or 1-methyl-2-pyrrolidone as solvent. Thiazines bearing an ester group at the C5 position rearranged at a considerably higher temperature than derivatives without substituents at this position into the corresponding pyrimidinethiones. This strictly thermal rearrangement was studied in detail using differential scanning calorimetry and density functional theory computational methods. The reaction pathway involves a zwitterionic intermediate. [source] High resolution solid-state,13C-NMR study of as-cured and irradiated epoxy resinsPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 9 2001Yvette Ngono-Ravache Abstract This article presents the effects of strong ionizing radiations on the physico-chemical modifications of aliphatic or aromatic amine-cured epoxy resins based on diglycidyl ether of bisphenol A (DGEBA). Such epoxy resins have a considerable number of applications in the nuclear industrial field and are known to be very stable under moderate irradiation conditions. Using extensively high resolution solid-state 13C-NMR spectroscopy we show that the aliphatic amine-cured resin (DGEBA-TETA) appears much more sensitive to gamma rays than the aromatic amine-cured one (DGEBA-DDM). On the one hand, qualitative analyses of the high resolution solid-state 13C-NMR spectra of both epoxy resins, irradiated under similar conditions (8.5 MGy), reveal almost no change in the aromatic amine-cured resin whereas new resonances are observed for the aliphatic amine-cured resin. These new peaks were interpreted as the formation of new functional groups such as amides, acids and/or esters and to alkene groups probably formed in the aliphatic amine skeleton. On the other hand, molecular dynamics of these polymers are investigated by measuring the relaxation times, TCH, T1,H and T1C,, before and after irradiation. The study of relaxation data shows the formation, under irradiation, of a more rigid network, especially for the aliphatic amine-cured system and confirms that aromatic amine-cured resin [DGEBA-4,4,-diaminodiphenylmethane(DDM)] is much less affected by ionizing radiations than the aliphatic amine-cured resin [DGEBA-triethylenetetramine(TETA)]. Moreover, it has been shown that the molecular modifications generated by irradiation on the powder of the aliphatic-amine-cured resin appear to be homogeneously distributed inside the polymers as no phase separations can be deduced from the above analyses. Copyright © 2001 John Wiley & Sons, Ltd. [source] Synthesis and In-Vitro Cytotoxicity Evaluation of Novel Naphtindolizinedione Derivatives, Part II: Improved Activity for Aza-AnaloguesARCHIV DER PHARMAZIE, Issue 2 2009Andrea Defant Abstract Our previous investigation on potential antitumor agents now got enriched by the evaluation of in-vitro activity against a full panel of NCI cancer cell lines for five new compounds. The concurrent presence in the molecular structure of a nitrogen atom in the aromatic system and a N,N -dimethylaminoethyl amide chain play a decisive role to enhance cytotoxicity. The N,N -anti compound 14 shows a higher activity than its N,N -syn isomer, exhibiting the best selective inhibition against the melanoma MALME-3M cell line, with a GI50 -value (= 30 nM) corresponding to a 330-fold increase in activity compared to the corresponding deaza-analogue. Compound 14 is efficiently synthesized by aminolysis of the ester obtained as a single regio-isomer by an one-pot three-component procedure involving metal-assisted cyclization under microwave irradiation conditions. [source] ChemInform Abstract: Metal-Catalyzed Reactions Between 2-Azabicyclo[2.2.1]hept-5-en-3-ones and Arylboronic Acids.CHEMINFORM, Issue 42 2010Takumi Abe Abstract Under microwave irradiation conditions, catalytic amounts of Cu(II) are sufficient to catalyze the N-arylation of bicycle (I) and analogues, whereas in the presence of a rhodium catalyst C-arylation occurs. [source] ChemInform Abstract: PEG-400 Catalyzed Reaction of the Synthesis of 2,4,6-Triarylpyridines and Crystal Structure of 2,4,6-Tris(4,-chlorophenyl)pyridine.CHEMINFORM, Issue 34 2010Qingpeng He Abstract A new and operationally simple procedure for the one-pot synthesis of triarylpyridines (III) mediated by PEG-400 under solvent-free and microwave irradiation conditions is described. [source] Pentiptycene-Derived Light-Driven Molecular Brakes: Substituent Effects of the Brake ComponentCHEMISTRY - A EUROPEAN JOURNAL, Issue 38 2010Wei-Ting Sun Abstract Five pentiptycene-derived stilbene systems (1,R; R=H, OM, NO, Pr, and Bu) have been prepared and investigated as light-driven molecular brakes that have different-sized brake components (1,H<1,OM<1,NO<1,Pr<1,Bu). At room temperature (298,K), rotation of the pentiptycene rotor is fast (krot=108,109,s,1) with little interaction with the brake component in the trans form ((E)- 1,R), which corresponds to the brake-off state. When the brake is turned on by photoisomerization to the cis form ((Z)- 1,R), the pentiptycene rotation can be arrested on the NMR spectroscopic timescale at temperatures that depend on the brake component. In the cases of (Z)- 1,NO, (Z)- 1,Pr, and (Z)- 1,Bu, the rotation is nearly blocked (krot=2,6,s,1) at 298,K. It is also demonstrated that the rotation is slower in [D6]DMSO than in CD2Cl2. A linear relationship between the free energies of the rotational barrier and the steric parameter A values is present only for (Z)- 1,H, (Z)- 1,OM, and (Z)- 1,NO, and it levels off on going from (Z)- 1,NO to (Z)- 1,Pr and (Z)- 1,Bu. DFT calculations provide insights into the substituent effects in the rotational ground and transition states. The molar reversibility of the E,Z photoswitching is up to 46,%, and both the E and Z isomers are stable under the irradiation conditions. [source] Screening of a Modular Sugar-Based Phosphite,Oxazoline Ligand Library in Asymmetric Pd-Catalyzed Heck ReactionsCHEMISTRY - A EUROPEAN JOURNAL, Issue 12 2007Yvette Mata Abstract We have synthesised a library of phosphite,oxazoline ligands derived from readily available D -glucosamine. These ligands have been successfully screened in the palladium-catalysed Heck reaction of several substrates with high regio- (up to 99,%) and enantioselectivities (ee's up to 99,%) as well as with improved activities under standard thermal conditions. The results indicate that the catalytic performance is highly affected by the oxazoline and biarylphosphite substituents and the axial chirality of the biaryl moiety of the ligand. The Heck reactions were also performed under microwave irradiation conditions, allowing a considerably shorter reaction time (full conversion in minutes) maintaining the excellent regio- and enantioselectivities. [source] | ||||||||||||||||