Sensitivity to light

To model the sensitivity of the BZ gels to hght, we mochfy Eq. (8.5) to the following  

The variable 4 accounts for the adchtional flux of bromide ions due to the hght [41[. With 4 = 0 in the above equation, we recover our expression for the system 

As noted in the Section 8.1, these synthetic BZ worms exhibit striking biomimetic behavior in their ability to move away from an adverse environmental condition, which in the context of the BZ reaction is the presence of light It is noteworthy that the latter action mimics the adaptive behavior of the sUme mold Physarum, which responds to nonuniform light illumination by moving toward the dark [42]. 

Financial support from the Army Research Office is gratefully acknowledged. 

Yashin, V.V. and Balazs, A.C. (2006) Pattern formation and shape changes in self-oscillating polymer gels. Science, 314(5800), 798-801. 

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The development of neutron diffraction by C G Shull and coworkers [30] led to the detennination of the existence, previously only a hypothesis, of antiferromagnetism and ferrimagnetism. More recently neutron diffraction, because of its sensitivity to light elements in the presence of heavy ones, played a cmcial role in demonstrating the importance of oxygen content m high-temperature superconductors. 

Forward recoil spectrometry (FRS) [33], also known as elastic recoil detection analysis (ERDA), is fiindamentally the same as RBS with the incident ion hitting the nucleus of one of the atoms in the sample in an elastic collision. In this case, however, the recoiling nucleus is detected, not the scattered incident ion. RBS and FRS are near-perfect complementary teclmiques, with RBS sensitive to high-Z elements, especially in the presence of low-Z elements. In contrast, FRS is sensitive to light elements and is used routinely in the detection of Ft at sensitivities not attainable with other techniques [M]- As the teclmique is also based on an incoming ion that is slowed down on its inward path and an outgoing nucleus that is slowed down in a similar fashion, depth infonuation is obtained for the elements detected. 

All the silver halides are sensitive to light, decomposing eventually to silver. In sunlight, silver chloride turns first violet and finally black. The use of these compounds in photography depends on this (see below). (All silver salts are, in fact, photosensitive—the neck of a silver nitrate bottle is black owing to a deposit of silver.)... 

Allyl Iodide. Use 29 g. (34 ml.) of allyl alcohol and 340 g. (200 ml.) of 57 per cent, hydriodic acid 84 g. of crude iodide are obtained. Upon adding 29 g. (34 ml.) of allyl alcohol to the combined residue in the flask and the aqueous layer and distilling as before, a further 72 g. of crude allyl iodide may be isolated. B.p. 99-101° (mainly 100°). The compound is very sensitive to light the distillation should therefore be conducted in a darkened room and preferably in the presence of a little silver powder. 

In humans, cases of dermatitis have been described after contact with DHBs. Combined exposure to hydroquinone and quinone airborne concentrations causes eye irritation, sensitivity to light, injury of the corneal epithelium, and visual disturbances (126). Cases with an appreciable loss of vision have occurred (127). Long-term exposure causes staining due to irritation or allergy of the conjunctiva and cornea and also opacities. Resorcinol and catechol are also irritants for eyes. 

Mercurous Bromide. Mercurous hi.omide[15385-58-7] Hg2Br2, is a white tetragonal crystalline powder, very similar to the chloride, and prepared in much the same way, ie, by the direct oxidation of mercury by bromine or by precipitation from mercurous nitrate by sodium bromide. It is sensitive to light, less stable than the chloride, and is not of appreciable commercial importance. 

Mercurous Iodide. Mercurous iodide [7783-30 ] Hg2l2, is a bright yellow amorphous powder, extremely insoluble in water and very sensitive to light. It has no commercial importance but may be prepared by precipitation, using mercurous nirate and potassium iodide. Care must be taken to exclude mercuric nitrate, which may cause the formulation of the water-insoluble mercuric iodide. 

Mercurous Sulfate. Mercurous s Ai2LX.e[7783-36-0] Hg2S04, is a colodess-to-shghfly-yellowish compound, sensitive to light and slightly soluble ia water (0.05 g/100 g H2O). It is more soluble ia dilute acids. The compound is prepared by precipitation from acidified mercurous nitrate solution and dilute sulfuric acid. The precipitate is washed with dilute sulfuric acid until nitrate-free. Its most important use is as a component of Clark and Weston types of standard cells. 

Chemical Sensitization. After the photographic microcrystals are precipitated but before they are coated on a support, the crystals are treated to enhance their sensitivity to light. Chemical sensitization is a process which improves that abiUty of the emulsion grains to use the absorbed photons, independent of the wavelength. Various methods of post-precipitation chemical sensitization have been developed to reduce the number of photons required to produce a developable latent-image center. 

Because of the multiple conjugated olefinic stmcture in the molecule, pure crystalline carotenoids are very sensitive to light and air and must be stored in sealed containers under vacuum or inert gas to prevent degradation. Thus, commercial utilization as food colorings was initially limited however, stable forms were developed and marketed as emulsions, oil solutions and suspensions, and spray-dried forms. 

Canthaxanthin crystallines from various solvents as brownish violet, shiny leaves that melt with decomposition at 210°C. As is the case with carotenoids in general, the crystals are sensitive to light and oxygen and, when heated in solution or exposed to ultraviolet light or iodine, form a mixture of cis and trans stereoisomers. Consequentiy, crystalline canthaxanthin should be stored under inert gas at low temperatures. Unlike the carotenoid colorants P-carotene and P-apo-8 -carotenal, canthaxanthin has no vitamin A activity. It is chemically stable at pH 2—8 (the range normally encountered in foods) and unaffected by heat in systems with a minimal oxygen content. 

Sensitive to lighting conditions degradation in storage contrast measurement from film subject to significant errors... 

Telluradiazolines are thermally stable crystal compounds, but they are very sensitive to light. When exposed to daylight, telluradiazolines undergo rapid decomposition, even in the solid state. By heating degassed solutions of telluradiazoline 79a in deuterochloroform or benzene, telluroketone 85 and alkenes 81 and 82 are formed in almost quantitative yield (93JA7019). 

Lichtelektron, n. photoelectron, lichtempfindlich, a. sensitive to light, optically sensitive,... 

Lichtempflndlichkeit, /. sensitivity to light, lichten, v.t. clear, thin expose to light weigh (anchor). 

HPO group is sensitive to light, but stable to heat. Using this MAI, St was thermally polymerized at the first step, and then MMA was photopolymerized at the second step [12]. Block efficiency was 40-55% and the amount of PSt homopolymer decreased, while that of PMMA homopolymer increased, presumably due to chain transfer reaction. 

In addition to a block copolymer, a microcapsule was made from suspension interfacial polycondensation between diacid chloride having aromatic-aliphatic azo group and aliphatic triamine [70,71]. The capsule was covered with a crosslinked structure having an azo group that was thermally stable but sensitive to light so as to be applicable to color photoprinting materials. 

Mercurous Nitrate (Mercury Protonitrate). HgN03.H20, mw 280.64, OB to HgO N2 +17.1%, mp 70° dec, bp explds, d 4.78g/cc. Short prismatic crysts effloresces and becomes anhydrous in dry air sensitive to light. Sol in small quantities of warm w (hydrolyzes in larger quantities), w acidified with nitric acid. Prepd by action of cold dil nitric acid upon an excess of Hg with slight warming. Highly toxic may explode if shocked or heated. There is no US Specification for Mercurous Nitrate Refs 1) Merck (1968), 6,62-L 2) CondChem-... 

Ethylnitrolic acid is an expl compd and forms numerous metallic salts, some of which are expls Potassium Salt. KC2H303N2, colorl amorph powder, si sol in methanol a weak expl Silver Salt. AgC2H303N2) white amorph powder, insol in w and dil ale. Sensitive to light,... 

Acrylonitrile, CH2= HCN Bromine addn or a trace of alkali Acrylonitrile Vapor 6000 kg/cm2 >200 Ammonia or Aromatic Amine as an inhibitor 17.3 481 Sensitive to light, strong bases or temps > 200°... 

Alkyl benzenesulfenates are sensitive to light and their preparation should be carried out in a darkened hood. 

Nanotechnology has led to very efficient versions of liposomes. Tiny hollow spheres only nanometers in diameter hold even tinier capsules of medicine. The spheres are made of silica covered with gold nanoparticles and when they are coated with antibodies they attach to tumor cells. The spheres are sensitive to light of specific wavelengths and when the light is applied, either heat up and destroy the tumor, or burst, releasing the drugs within the capsules directly into the tumor. 

Polymer films that are sensitive to light, x-rays, or electrons— known as photoresists—are nsed extensively to transfer the pattern of an electronic circuit onto a semiconductor surface. Such films must adhere to the semiconductor surface, cross-link or decompose on exposure to radiation, and nndergo development in a solvent to achieve pattern definition. Virtually all aspects of photoresist processing involve surface and interfacial phenomena, and there are many outstanding problems where these phenomena mnst be controlled. For example, the fabrication of multilayer circuits requires that photoresist films of about 1-pm thickness be laid down over a semiconductor surface that has already been patterned in preceding steps. 

Because Me3SiI (TIS) 17 is relatively expensive and very sensitive to light, air, and humidity, it is usually prepared in situ from TCS 14 and Nal in acetonitrile [1-6], although other solvents such as CH2CI2, DMF, benzene, or hexane have also been used [5, 6] (Scheme 12.1). It is assumed that TIS 17 forms, in situ, with MeCN, a (T-complex 1733 [2, 3-6], yet Me3SiI 17 can also be prepared by treatment of hex-amethyldisilane 857 with iodine in organic solvents [4-6]. The chemistry of TIS 17 has been reviewed [4—6]. 

More natural colorants are wanted for beverage applications, but certain issues must be considered technical properties such as stability, sensitivity to light, pH, and temperature, and interactions with other ingredients and packaging. Some natural... 

Chemically pure semiconducor materials can absorb only those photons, the energy hv of which exceeds the band gap E . Therefore, E. value determines the "red boundary of the light that is used in photocatalytic action of these materials. By way of example. Table 1 presents the values of Eg and the corresponding values of boundary wave length Xg= hc/E (where c is the velocity of light) for some semiconductor and dielectric oxides [2]. However, a semiconductor PC can be sensitized to light with X> by chemical modifications of its surface layer or adsorption of certain molecules on its surface, provided that such treatment creates additional full or empty electron levels in the band gap of the semiconductor material. 

A9-THC (2.1 in Fig. 2) is the only major psychoactive constituent of C. sativa. It is a pale yellow resinous oil and is sticky at room temperature. A9-THC is hpophihc and poorly soluble in water (3 p,g mL ), with a bitter taste but without smell. Furthermore it is sensitive to light and air [4]. Some more physical and chemical data on A9-THC are fisted in Table 1. Because of its two chiral centers at C-6a and C-lOa, four stereoisomers are known, but only (-)-trans-A9-THC is foimd in the Cannabis plant [5]. The absolute configuration of the... 

The use of glass apparatus to carry out reactions sensitive to light causes accidents. 

The diiodo compounds are very sensitive to light and are seldom used in syntheses. 

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