scholarly journals Irradiation Effect on Stability of Plasticized Poly(Fluorostyrene) Isomers in Solution

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Khalid E. Al Ani ◽  
Afrah Essa Ramadhan ◽  
Mai Anabtawi

The UV irradiation and blending effects on stability of Poly(Fluorostyrene) isomers in solution were studied at different intervals of irradiation time in presence of air. The increase in irradiation time of these isomers caused an increase in the intensity of the absorption band and an increase in the intensity of the absorption of new broad band at longer wavelength, thus indicating a possibility of photodegradation of polymeric chains. The influence of added dioctyl phthalate and dioctyl terephthalate plasticizers on photooxidative degradation was also investigated and was found to increase the photodegradation processes in polymeric chains. On the other hand, the intensity of excimer and monomer fluorescence bands maxima was also found to decrease with increase in irradiation times. These changes may be attributed to the formation of new photoproducts resulted from the photodegradation of irradiated polymeric chains. The decrease in polarity of used solvents caused a considerable enhancement to the intensity of the polymer fluorescence band and accelerated photodegradation. A proposed mechanism is suggested to account for the effects of added plasticizers, the increase in irradiation time, and polarity of solvents on photodegradation and photooxidation processes in polymeric chains.

2015 ◽  
Vol 35 (2) ◽  
pp. 159-167 ◽  
Author(s):  
Afrah E. Ramadhan

Abstract The effects of UV irradiation and blending on the stability of poly (α-methylstyrene) (PαMS) in solid films were studied at different intervals of irradiation time in the presence of air, by absorption, emission and Fourier transform infrared (FT-IR) spectroscopy. The increase in irradiation time caused an increase in the intensity of the absorption band of the polymer, and an increase in the intensity of absorption of a new broad band at a longer wavelength, thus indicating the possibility of photodegradation of polymeric chains. The influence of added plasticizers, dimethyl terephthalate (DMT), diethyl terephthalate (DET), dibutyl phthalate (DBP), dioctyl phthalate (DOP) and dioctyl terephthalate (DOT) on photoquenching of the polymer fluorescence band was also investigated, and found to increase the photoquenching processes with increase in the amount of added plasticizers. By contrast, the intensity of excimer and monomer fluorescence bands was also found to decrease with increase in irradiation times. These changes may be attributed to the formation of new photoproducts which resulted from the photodegradation and photooxidation of irradiated polymeric chains. In addition, the observed increase in the intensities of the carbonyl and hydroxyl regions of the FT-IR spectra provides evidence for the photooxidation of polymeric chains. The increase in the intensity of some bands and the disappearance of new bands indicate the photodegradation of polymeric chains.


2021 ◽  
Vol 11 (12) ◽  
pp. 5427
Author(s):  
Arturo Sanchez-Perez ◽  
Nuria Cano-Millá ◽  
María José Moya Villaescusa ◽  
José María Montoya Carralero ◽  
Carlos Navarro Cuellar

Photoactivation with ultraviolet C light can reverse the effects derived from biological ageing by restoring a hydrophilic surface. Ten titanium discs were randomly divided into three groups: a control group, a 6 W group, and an 85 W group. A drop of double-distilled, deionized, and sterile 10 µL water was applied to each of the discs. Each disc was immediately photographed in a standardized and perpendicular manner. Measurements were taken based on the irradiation time (15, 30, 60, and 120 min). UVC irradiation improved the control values in both groups. There was no difference in its effect between the 6 W group and the other groups during the first 30 min. However, after 60 min and up to 120 min, 85 W had a significantly stronger effect. The contact angles with the 85 W ultraviolet light source at 60 and 120 min were 19.43° and 31.41°, respectively, whereas the contact angles for the 6 W UVC source were 73.8° and 61.45°. Power proved to be the most important factor, and the best hydrophilicity result was obtained with a power of 85 W for 60 min at a wavelength of 254 nm.


1925 ◽  
Vol s2-69 (276) ◽  
pp. 703-729
Author(s):  
W. N. F. WOODLAND

1. Those species of Proteocephalid Cestodes in which the testes are situated in the cortex may be described as of the Monticellia type. Of this type there are three conditions : (a) the Monticellia condition in which the testes, uterus, ovary, and vitellaria are all situated in the cortex; (b) the Rudolphiella condition in which the testes and vitellaria alone are in the cortex, the other organs being entirely or almost entirely in the medulla ; and (c) the Marsypocephalus condition in which the testes alone are in the cortex, all other organs being medullary. Fuhrmann's genus Goezeella is synonymous with Monticellia if we ignore the characters of the scolex as features of generic value. 2. The anatomy of two species of Marsypocephalus is described: Marsypocephalus rectangulus Wedl, 1862, and Marsypocephalus heterobranchus, n.sp., from Nile Siluroid fishes. 3. It is concluded that the cortical situation of the testes and other organs is a taxonomic feature of generic value only (as in Pseudophyllidea in the case of the vitellaria) and La Rue's new family of the Monticellidae, created to include Monticellia-like forms, is not accepted. Monticellia, Rudolphiella, and Marsypocephalus are thus regarded as new genera in the Proteocephalidae. 4. The facts that the ‘Corallobothrium’ type of scolex is found in all of the three genera Monticellia (as amended by me and including ‘Goezeella’ siluri, Fuhrmann), Rudolphiella, and Proteocephalus (as amended by me and including ‘Corallobothrium’ solidum, Fritsch), and that in the Caryophyllaeidae, Bothriocephalidae, and Cyclophyllidea (cf. e.g. Taenia solium and Taenia saginata) minor scolex characters are evidently only features of specific value, compel us to delete such genera as Corallobothrium, Choanoscolex, Acanthotaenia, and my own recent genus Gangesia and to regard them as synonyms of Proteocephalus (La Rue's genus ‘Ophiotaenia’, syn. ‘Crepidobothrium’, not being accepted). Fuhrmann's Goezeella siluri becomes Monticellia siluri, and Fritach's Corallobothrium solidum becomes Proteocephalus solidus. The genera of the Proteocephalidae are thus four in number: Proteocephalus , Monticellia, Rudolphiella , and Marsypocep, halus, and these are formally or informally redefined. The two species of Marsypocephalus are diagnosed. 5. The ‘Taenia malopteruri’ of Fritsch, 1886, is not of the Monticellia type, as suggested by La Rue. Its structure is of the usual Proteocephalid type, save that the scolex possesses a rostellum and a broad band of hooklets and is covered with spinelets. It is renamed Proteocephalus malopteruri. 6. A new species of Clestobothrium--Clestobothrium clarias, from Clarias anguillaris Günth-is described. It is of interest, not only as being the third (second ?) species known of the genus, but because it affords one more illustration of the fact that the characters of the scolex cannot be used for diagnoses of genera. For this reason also, Lönnberg's genus Ptychobothrium (1889) becomes synonymous with Diesing's genus Polyonchobothrium (1884).


1964 ◽  
Vol 20 ◽  
pp. 358-370
Author(s):  
L. H. Aller ◽  
D. J. Faulkner

The present investigation is concerned with the energy distributions in globular clusters. In a sense, energy-distribution measurements are comparable with multi-colour photometry. The chief advantage is that narrower band-passes may be used and the entire spectrum traced, whereas in multi-colour photometry one is limited to effective wavelengths determined by the filter and a rather broad band-pass. On the other hand, broad band-pass photometry often permits one to cover a broader spectral range, and to work much faster. Since the time required for a single observation is much shorter, the observer is less at the mercy of the sky transparency. Hence a greater accuracy can be obtained.


1998 ◽  
Vol 188 ◽  
pp. 291-292
Author(s):  
T. Toneri ◽  
K. Hayashida ◽  
M. Loewenstein

M32 is the nearest dwarf elliptical galaxy. Its center is known to have a mass concentration of 3 × 106 M⊙, which is usually interpreted as an evidence of a super massive black hole. We observed M32 with ASCA two times in July and August of 1996. An X-ray source was detected at the center of M32 and its first broad-band X-ray spectra were obtained. ASCA observations of M32 limit the activity of the central black hole to be less than 10−6 times of the Eddington limit. We also found two other bright sources within 12 arcmin from the M32 center. One is the newly appeared X-ray source and the other is G144. In this paper, we summarize the results on the new source and G144. For M32, please refer to the publication (Loewenstein et al. 1997).


1963 ◽  
Vol 2 (2) ◽  
Author(s):  
Paul N. Dimotakis

SummaryThe γ-pre-irradiation effect on the recombination of recoil cobalt atoms in some neutron irradiated crystalline cobaltic complexes was examined. The introduction of defects into the lattice by pre-irradiation seems to increase the initial retention and promotes the annealing phenomenon, though on the other hand radiolytic phenomena may also appear. Plots of isothermal annealing curves appear to indicate the existence of two or more parallel consecutive recombination-decomposition reactions. A kinetic interpretation of such mixed phenomena is also given. Complex kinetic phenomena also appear to be quite general in annealing processes for systems already studied by other authors. These systems, if examined in this light, may lead to a new interpretation as to the way in which recombination occurs during annealing.


1972 ◽  
Vol 50 (6) ◽  
pp. 782-791 ◽  
Author(s):  
Eric A. Shaede

Radicals formed by γ-irradiation of propylene carbonate (PC) glasses at 77 °K were studied by e.s.r. and optical spectroscopy. Trapped electrons were identified by their narrow (ΔHms = 4.5 G) Gaussian e.s.r. line at g = 2.0028 which was completely resolved from the radical spectrum. The trapped electrons were unstable at 77 °K. They decayed fairly rapidly via a process exhibiting non-homogeneous kinetics believed to be reaction with positive ions. The temperature dependence of the e.s.r. spectra of the other radicals formed is discussed although conclusive assignment of the lines could not be made.Ultraviolet photolysis of the radicals in the irradiated PC glasses produced new species identified as HCO, CO3−, and CH3 by their characteristic e.s.r. spectra. In addition, a complex optical absorption band in the 500–750 nm region was assigned to a combination of the absorption bands of the CO3− radical anion and the HCO radical.


1988 ◽  
Vol 66 (9) ◽  
pp. 2412-2421 ◽  
Author(s):  
Steven W. Anderson ◽  
Keith Yates

The reactivity–selectivity properties of the sec-phenethyl carbenium ion and its analogues have been examined in binary-aqueous solutions of alcohols (ROH; R = Me, Et, CF3CH2, n-Bu, t-Bu, n-Pr, i-Pr), acetic acid, and in solutions containing external nucleophiles such as thiophenol, ethanethiol, acetate, and benzenesulfinate. Selectivity (S = k(Nuc)/k(H2O)) is observed to be a function of the nucleophile, the ring substituent, thermal or photochemical conditions, irradiation time, and medium acidity. In the case of styrene, the photochemically generated (usually 254 nm, 1 h) species exhibits greater selectivity (up to two orders of magnitude) than its thermal counterpart, generated (usually 80 °C, 2−4 d) in identical media, particularly in aqueous-rich solvent compositions. A rationale for these differences, supported by fluorescence quenching experiments, and the other effects upon selectivity will be discussed.


1961 ◽  
Vol 42 (3) ◽  
pp. 151-165 ◽  
Author(s):  
Jay S. Winston ◽  
Lloyd Tourville

The cloud structure of an occluded cyclone and its environs over the Gulf of Alaska is revealed in detail by a series of TIROS pictures. The pictures clearly portray:(1) the nature and extent of dense cloudiness around the inner core of the cyclone;(2) a broad band of cloudiness associated with the main polar front;(3) the pattern of overrunning cloudiness marking a newly developing wave south of the main storm;(4) a previously undetected, old cyclonic vortex in mid-troposphere; and(5) the striking cellular arrangement of cumuliform clouds in the cyclonic flow to the rear of the storm. These features are related to the conventional meteorological data and analyses over this area and are found in many places to corroborate them rather well. On the other hand, there are several places, particularly in view of the sparsity of conventional data, where the cloud pictures suggest that improvements could be made in the map analyses and numerically computed vertical motions on the basis of the TIROS cloud information.


2003 ◽  
Vol 58 (7-8) ◽  
pp. 411-418
Author(s):  
A. Kawski ◽  
B. Kukliński ◽  
P. Bojarski

The effect of the time of irradiation with the excitation wavelength λexc on the absorption and emission spectra of p-cyano-N,N-dimethylaniline (CDMA), p-cyano-N,N-diethylaniline (CDEA) and N,N- dimethylaniline (DMA) in acetonitrile and in n-hexane, as well as the effect of high temperature is studied. It is found that after sufficiently long irradiation of CDMA and CDEA in acetonitrile the short wavelength SE band intensity strongly increases compared to that of the long wavelength LE band. This phenomenon is caused by the photolysis of CDMA and CDEA in polar solvents. In each case both the irradiation time and the delivery of suitable thermal energy leads to irreversible processes. Investigations of the λexc effect on the location and intensity distribution of emission bands have shown their independence of λexc ranging from 260 nm to 330 nm in the LE band. However, a pronounced effect of λexc on the intensity appears in the SE band. In this spectral region DMA molecules formed due to the photolysis of CDMA absorb strongly. Excitation at λexc = 340 - 360 nm in the dimeric absorption band leads to a new emission band overlapping the LE band, which indicates the presence of luminescing dimers.


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