278 research outputs found
Developing methods for testing the resistance of white cabbage against Thrips tabaci
No full textSince the damage of the onion thrips (Thrips tabaci Lindemann) first occurred on white cabbage in Hungary several observations have been carried out, both in Hungary and abroad, to assess varietal resistance. The use of a new evaluation method for field screening is described and the result of the monitoring of 64 varieties is reported. The most susceptible varieties were ‘Bejo 1860’, ‘SG 3164’, ‘Quisto’, ‘Green Gem’ and ‘Ramada’. On the other hand, ‘Golden Cross’, ‘Balashi’, ‘Riana’, ‘Autumn Queen’, ‘Leopard’, Ama-Daneza’ and ‘Galaxy’ suffered the least damage under natural infestation. Methods for testing the patterns of resistance are also described and evaluated. In case of plants at the few leaf growth stage significant negative correlation was found between egg mortality and the egg laying preference of adults. The results of the other antibiotic and antixenotic tests were greatly affected by differences in the physiological age and condition of the varieties
Raman and infrared spectroscopic studies of kaolinite surfaces modified by intercalation
No full textInvestigation of SnO2 thin film evolution by thermoanalytical and spectroscopic methods
No full textThe thermal evolution process of a SnO2 thin film from SnCl2*2H2O precursor dissolved in ethanol was followed by
thermogravimetry combined with mass spectrometry (TG-MS), diffuse reflectance Fourier transform infrared spectroscopy
(DRIFT) and infrared emission spectrometry (IRES). The precursor salt solution was deposited on a titanium metal sheet. After evaporation of the solvent, the gel-like film was heated in a thermobalance in an oxidative environment to 600 °C. Mass
spectrometric ion intensity curves showed the liberation of chlorinated species, alcoholic fragments and CO2 as combustion
product and from the decomposition of surface carbonyls, carboxylates and carbonates. The presence of O–H, C–H and C–O
bands in the infrared spectra was confirmed and their assignment was made by the deconvolution of the recorded curves as a function of the firing temperature
Investigation of IrO2/Ta2O5 thin film evolution
No full textThe thermal evolution process of IrO2–Ta2O5/Ti coatings with varying noble metal content has been investigated under in situ conditions by thermogravimetry combined with mass spectrometry. The gel-like films prepared from alcoholic solutions of the precursor salts (IrCl3·3H2O and TaCl5) onto titanium metal support were heated in an atmosphere containing 20% O2 and 80% Ar up to 600 °C. The liberation of the chlorinated species followed by the mass spectrometric ion intensity curves showed that the two oxide phases do not develop independently.\ud
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The cracking of retained solvent, the combustion of organic surface species formed (and elemental carbon trapped in the film) was also followed by the MS curves. The formation of carbonyl- and carboxylate-type surface species connected to the noble metal were identified by Fourier transform infrared emission spectroscopy (IRES). These secondary processes—catalyzed by the noble metal—play an important role in the development of surface morphology of the films when used as anode materials in oxygen evolution reactions
Raman spectroscopy of potassium acetate-intercalated kaolinites over the temperature range 25-300,°C
No full textRaman spectra of the hydroxyl-stretching region of potassium acetate-intercalated kaolinite were obtained under an atmosphere of both air and nitrogen using a thermal stage over the temperature range 25-300 °C. At 25 °C, an additional band at 3606 cm-1 attributed to the inner surface hydroxyl hydrogen bonded to the acetate ion is observed with a concomitant loss of intensity in the bands attributed to the inner surface hydroxyls. Heating the intercalated complex to 50 °C results in two hydroxyl-stretching wavenumbers at 3594 and 3604 cm-1. At 100 °C, the bands shift to 3600 and 3613 cm-1. At temperatures from 100 to 300 °C, bands are observed in similar positions. Upon cooling in air to 25 °C, the acetate-bonded inner surface hydroxyl stretching wavenumber shifts back to 3606 cm-1. Upon heating the intercalated kaolinite to 300 °C under an atmosphere of nitrogen and upon cooling the acetate-bonded inner surface hydroxyl stretching wavenumber is observed at 3601 cm-1. Upon cooling to 150 °C and subsequently to 25 °C, two bands are observed at 3611 and 3600 cm-1. Upon rehydration, the hydroxyl stretching wavenumber returns to 3606 cm-1. The changes in the Raman spectra of the hydroxyl-stretching region during dehydration and rehydration are reversible. When the potassium acetate-intercalated kaolinite is heated to 300 °C and cooled to 25 °C, the inner-hydroxyl band is observed at 3630 cm-1. The shift in the wavenumber of the inner hydroxyl band is attributed to the insertion of the potassium ion in the ditrigonal cavity of the siloxane layer
Modification of the Hydroxyl Surface in Cesium Acetate Intercalated Kaolinite
No full textChanges in the hydroxyl surfaces of cesium acetate intercalated kaolinite have been studied over the ambient to predehydroxylation temperature range using a combination of FTIR and Raman spectroscopy, combined with X-ray diffraction. Upon intercalation of a low-defect kaolinite with cesium acetate, the kaolinite layers expanded to 14.0 Å. Upon heating the intercalate to 50 C, the kaolinite expands to 17.0 Å. Over the temperature range 100-200 C, a third phase with a d(001) spacing of 12.80 Å was observed. These expansions are reversible, and upon cooling the intercalation complex and upon exposure to air for sufficient lengths of time, the d(001) spacing returned to 14.0 Å. These expansions are in harmony with thermal decomposition measurements. Diffuse reflectance spectroscopy shows that the cesium acetate intercalated kaolinite is almost completely intercalated and that the thermal treatment of the intercalate is reversible. The Raman spectrum of the hydroxyl stretching region of the intercalated kaolinite showed a new band at 3606 cm-1, which was attributed to the inner surface hydroxyl hydrogen bonded to the acetate ion. Mild heating of the intercalated complex to 50 C caused a rearrangement of the surface structure with a Raman band being observed at 3610 cm-1. It is proposed that the 3610 cm-1 band is associated with the 17.0 Å phase and that the 3606 cm-1 band is associated with the 14.0 Å phase. Further thermal treatment over the 100-200 C temperature ranges resulted in two hydroxyl bands at 3618 and 3609 cm-1. The 3618 cm-1 band is attributed to the inner hydroxyl. At the predehydroxylation temperature for cesium acetate intercalated kaolinite (~300 C), two bands were observed at 3609 and 3619 cm-1. Above this temperature, no hydroxyls are spectroscopically evident. Upon cooling to room temperature, the Raman spectra of the hydroxyl surfaces are identical to that of the initial intercalation complex, showing that the thermal modification of the kaolinite surfaces is reversible. The thermal treatment results in some minor deintercalation
Modification of Kaolinite Surfaces through Intercalation with Deuterated Dimethylsulfoxide
No full textThe surfaces of kaolinite have been modified through intercalation with deuterated dimethylsulfoxide (d-DMSO). X-ray diffraction shows the kaolinite to be expanded from 7.2 to 11.19 Å. Modification of the surface has been explored through (a) changes to the hydroxyl surfaces of the kaolinite and (b) through changes to the d-dimethylsulfoxide inserting molecule. Upon intercalation of the kaolinite with d-DMSO, additional infrared bands at 3660, 3538, and 3502 cm-1 and additional Raman bands at 3660, 3537, 3507, and 3480 cm-1 are observed. The first band at 3660 cm-1 is attributed to the inner-surface hydroxyls hydrogen bonded to the d-DMSO and the other bands to water hydroxyl-stretching modes. Both infrared and Raman spectroscopy shows that significant changes in the molecular structure of the d-DMSO occur upon intercalation. First, the CD stretching modes observed for d-DMSO at 2125 and 2249 cm-1 in the DRIFT spectrum lose the degeneracy and split into 2140 and 2127 cm-1 and 2267, 2250, and 2238 cm-1. The Raman spectrum shows this loss of degeneracy through the bands observed at 2272, 2267, 2263, and 2251 cm-1 for the antisymmetric CD stretching vibration and at 2129 and 2141 cm-1 for the symmetric stretching vibrations. Upon intercalation with d-DMSO, the S=O stretching region shows bands at 1066, 1023, and 1010 cm-1. The 1066 cm-1 band is assigned to the free monomeric S=O group and the 1023 and 1010 cm-1 bands to two different polymeric S=O groups. Bands attributed to the CS stretching vibrations, the in-plane and out-of-plane S=O bending and the CSC symmetric bends all move to higher frequencies upon intercalation with d-DMSO. It is proposed that intercalation depends on the presence of water and that the additional bands at 3536 and 3501 cm-1 are due to the presence of water. The precise positions of the hydroxyl stretching modes of water at these positions suggest that water is in a well-defined position within the intercalation structure
The effect of quartz content on the mechanochemical activation of kaolinite
No full textThe mechanochemical activation (dry grinding) causes destruction in the crystal structure of kaolinite by the rupture of the O–H, Al–OH, Al–O–Si, and Si–O bonds. The major mineral constituents of natural kaolins are kaolinite and quartz. In this study, the attention was mainly directed to the role of quartz content (4, 25, 50, and 75 wt%) in the mechanochemical amorphization of kaolinite. Grinding experiments were carried out for 1, 2, 3, and 4 h in a planetary mill. The rate of destruction of the kaolinite structure was followed by X-ray diffraction, thermal analysis, and Fourier transform infrared (DRIFT) spectrometry. The distortion and rupture of the kaolinite structure induced by grinding was reflected in line broadening, increases in mean lattice strain, and reduction of peak areas (intensities). The increased quartz content resulted in acceleration of the mechanically induced amorphization of the kaolinite structure. The crystalline order of kaolinite was completely destroyed after grinding the sample containing 75 wt% quartz for 4 h. On the other hand, 4 h of grinding was sufficient only to cause some increase in the defect density of kaolinite in the case of samples with lower quartz contents (25 and 4 wt%). The results indicate that quartz grains act as grinding bodies during the intensive dry grinding of kaolinite
Experiências limiares em L'Analphabète, de Agota Kristof
No full textIn the autobiography L'Analphabète, Agota Kristof revisits some periods in her life, marked by a most surprising writing experience: the author, of Hungarian origin, abandoned her mother tongue to write in French, the language of the region where she went into exile, in Switzerland. Apart from this linguistic diaspora, the author portrayed in this short text the most fundamental phases of the artistic journey marked by the principle of denial: she is the foreigner, the exiled, the writer suddenly rendered illiterate, seeking, through learning a language, with which she never had contact, the recovery of her writing and her own split identity. These periods, analyzed in light of Walter Benjamin's concept of threshold, as explained by Jeanne-Marie Gagnebin and João Barrento, and having as their guiding thread their relationship with reading and writing, can offer us a vigorous reading of the work, in order to recover the importance of rites of passage in a context of war, exile and social exclusion.Na autobiografia L’Analphabète, Agota Kristof revisita alguns períodos na sua vida, marcados por uma experiência de escrita das mais surpreendentes: a autora, de origem húngara, abandonou o idioma materno para escrever em francês, língua da região onde se exiliou, na Suíça. À parte esta diáspora linguística, a autora retratou nesse curto texto as fases mais fundamentais de um percurso artístico marcado pelo princípio da negação: ela é a estrangeira, a exilada, a escritora tornada, de repente, analfabeta, buscando, através da aprendizagem da uma língua, com qual nunca travou contato, a recuperação da sua escrita e da sua própria identidade cindida. Esses períodos, analisados à luz do conceito de limiar, de Walter Benjamin, conforme o explicam Jeanne-Marie Gagnebin e João Barrento, e tendo como fio condutor a sua relação com a leitura e com a escrita, podem oferecer-nos uma leitura vigorosa da obra, no sentido de recuperar a importância dos ritos de passagem num contexto de guerra, exílio e exclusão social.
 
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