Observation and application of optical interference and diffraction effects in reflection from photochemically fabricated Gaussian interfaces

Koker, L.; Kołasiński, Kurt W.

doi:10.1063/1.370972

Cited by 18 publications

(14 citation statements)

References 41 publications

(36 reference statements)

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“…To confirm that r exp corresponds to a constant value of d max , we have measured r air for a number of crystals after the por-Si has been removed. We then apply the optical procedure described previously 38 in which d max ) |g b |. The collected values of r air and d max are shown in Table 2.…”

Section: Experimental Section 21 Determination Of Rate In Various Fmentioning

confidence: 99%

“…The outer radius of circular patterns contained in the reflected laser beam increases as etching proceeds and the radius is related to the depth of etching. Optical analysis 37,38 reveals a linear relationship between the outer radius of the patterns when inspected in air without a por-Si film, r air , and the depth of etching, d max . Experimental justification is given here (Section 3) for a linear relationship between d max and the radius measured in situ, r exp , under the conditions of our experiments.…”

Section: Si + 6hfmentioning

confidence: 99%

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Laser-Assisted Formation of Porous Si in Diverse Fluoride Solutions: Reaction Kinetics and Mechanistic Implications

Koker

Kołasiński

2001

J. Phys. Chem. B

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The formation rate of porous silicon by photoelectrochemical etching of n-type silicon is measured in situ by a novel technique. The reflection of the laser beam used to drive the reaction contains circular patterns, the outer radius of which bears a linear relationship to the depth of etching. The use of the radius to measure etch rate and the absolute depth of etching is described and justified. The rates are analyzed in terms of the calculated activities of the different species in solution. A rate equation, which is first order in HF and HF 2 -, is deduced and rate coefficients calculated. It is concluded that the etching mechanism includes two parallel rate-determining steps involving HF and HF 2 -and that the HF 2 -channel is roughly 20 times faster than the HF channel. In light of our data, previously proposed mechanisms of Si dissolution in fluoride solutions should be reevaluated.

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Section: Experimental Section 21 Determination Of Rate In Various Fmentioning

confidence: 99%

Section: Si + 6hfmentioning

confidence: 99%

Laser-Assisted Formation of Porous Si in Diverse Fluoride Solutions: Reaction Kinetics and Mechanistic Implications

Koker

Kołasiński

2001

J. Phys. Chem. B

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“…The experimental apparatus is as described previously [11,12,23]. Samples of Si(111) of about 1 cm 2 and 0.5 mm thickness were cut from n-type (ρ = 4.5-10.4 Ω cm) silicon wafers, polished on one side.…”

Section: Methodsmentioning

confidence: 99%

Etchant composition effects on porous silicon morphology and photoluminescence

Koker

Wellner

Sherratt

et al. 2003

phys. stat. sol. (a)

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Laser assisted etching of n-type silicon, without an applied potential, to form porous silicon has been studied in a variety of etchants. The range of pore diameters correlates with the ratio of the activities of HF and 2 HF − . Where the activity ratio 2 HF − : HF is low, small (<10 nm) pores are formed, while where 2 HF − : HF is high only larger pores (20-100 nm) are observed. The dependence of pore morphology on etchant composition demonstrates the importance of specific etch chemistry during pore formation. The composition of the film is also affected by the etchant. In particular hexafluorosilicates can deposit during porous silicon formation in solutions containing K + , Rb + and Cs + . The presence of hexafluorosilicates strongly affects the photoluminescence from the layers. We ascribe the strong, blue-shifted photoluminescence to emission from states at the hexafluorosilicate/Si interface.

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“…Since the accumulation of lactate in the blood during intensive exercise coincides with a decrease in fatty acid oxidation, a direct effect of lactate on fatty acid release from adipocytes has been suggested (Issekutz and Miller, 1962; Fredholm, 1971; Boyd et al, 1974). Although a causal link between elevated lactate levels and decreased fatty acid release and oxidation is plausible, no evidence for this concept has been provided; it has rather remained controversial (Trudeau et al, 1999). Exercise studies on wild type and HCA 1 -deficient mice that were trained to exercise at an intensity to reach plasma levels of lactate sufficient to activate HCA 1 , showed no differences in free fatty acid or glycerol plasma concentrations between wild type and HCA 1 -deficient mice (Ahmed et al, 2010).…”

Section: Biological Roles Of Hca Receptorsmentioning

confidence: 99%

Biological Roles and Therapeutic Potential of Hydroxy-Carboxylic Acid Receptors

Ahmed¹

2011

Front. Endocrin.

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In the recent past, deorphanization studies have described intermediates of energy metabolism to activate G protein-coupled receptors and to thereby regulate metabolic functions. GPR81, GPR109A, and GPR109B, formerly known as the nicotinic acid receptor family, are encoded by clustered genes and share a high degree of sequence homology. Recently, hydroxy-carboxylic acids were identified as endogenous ligands of GPR81, GPR109A, and GPR109B, and therefore these receptors have been placed into a novel receptor family of hydroxy-carboxylic acid (HCA) receptors. The HCA1 receptor (GPR81) is activated by the glycolytic metabolite 2-hydroxy-propionic acid (lactate), the HCA2 receptor is activated by the ketone body 3-hydroxy-butyric acid, and the HCA3 receptor (GPR109B) is a receptor for the β-oxidation intermediate 3-hydroxy-octanoic acid. While HCA1 and HCA2 receptors are present in most mammalian species, the HCA3 receptor is exclusively found in humans and higher primates. HCA receptors are expressed in adipose tissue and mediate anti-lipolytic effects in adipocytes through Gi-type G protein-dependent inhibition of adenylyl cyclase. HCA2 and HCA3 inhibit lipolysis during conditions of increased β-oxidation such as prolonged fasting, whereas HCA1 mediates the anti-lipolytic effects of insulin in the fed state. As HCA2 is a receptor for the established anti-dyslipidemic drug nicotinic acid, HCA1 and HCA3 also represent promising drug targets and several synthetic ligands for HCA receptors have been developed. In this article, we will summarize the deorphanization and pharmacological characterization of HCA receptors. Moreover, we will discuss recent progress in elucidating the physiological and pathophysiological role to further evaluate the therapeutic potential of the HCA receptor family for the treatment of metabolic disease.

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Observation and application of optical interference and diffraction effects in reflection from photochemically fabricated Gaussian interfaces

Cited by 18 publications

References 41 publications

Laser-Assisted Formation of Porous Si in Diverse Fluoride Solutions: Reaction Kinetics and Mechanistic Implications

Laser-Assisted Formation of Porous Si in Diverse Fluoride Solutions: Reaction Kinetics and Mechanistic Implications

Etchant composition effects on porous silicon morphology and photoluminescence

Biological Roles and Therapeutic Potential of Hydroxy-Carboxylic Acid Receptors

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