Rapid crack growth in a thermoelastic solid under mixed-mode thermomechanical loading

A two-dimensional steady-sate analysis of semi-infinite brittlecrack growth at a constant subcritical rate in an unboundedfully-coupled thermoelastic solid under mixed-mode thermomechanicalloading is made. The loading consists of normal and shear tractionsand heat fluxes applied as point sources (line loads in theout-of-plane direction). A related problem is solved exactly in an integral transformspace, and robust asymptotic forms used to reduce the originalproblem to a set of integral equations. The equations are partiallycoupled and exhibit operators of both Cauchy and Abel types,yet can be solved analytically. The temperature change field at a distance from the moving crackedge is then constructed, and its dominant term is found tobe controlled by the imposed heat fluxes. The role of this termis, indeed, enhanced if the heat fluxes serve to render thecrack as a net heat source/sink for the solid, as opposed tobeing a transmitter of heat across its plane. More generally,the influence of the thermoelastic coupling on this field, aswell as other functions, is found to increase with crack speed.     

Intramolecular Fluorocyclizations of Unsaturated Carboxylic Acids with a Stable Hypervalent Fluoroiodane Reagent

A new class of fluorinated lactones was prepared by the intramolecular fluorocyclizations of unsaturated carboxylic acids by using the stable fluoroiodane reagent in combination with AgBF₄. This unique reaction incorporates a cyclization, an aryl migration, and a fluorination all in one step. The fluoroiodane reagent, prepared easily from fluoride, can also be used without a metal catalyst to give moderate yields within just 1 hour, thus demonstrating that it is a suitable reagent for developing new ¹⁸F‐labelled radiotracers for PET imaging.     

Holographic optical elements as scanning lidar telescopes

We have developed and investigated the use of holographic optical elements (HOEs) and holographic transmission gratings for scanning lidar telescopes. Rotating a flat HOE in its own plane with the focal spot on the rotation axis makes a very simple and compact conical scanning telescope. We developed transmission and reflection HOEs for use at the first three harmonic wavelengths of Nd:YAG lasers. The diffraction efficiency, diffraction angle, focal length, focal spot size and optical losses were measured for several HOEs and holographic gratings, and found to be suitable for use as lidar receiver telescopes, and in many cases could also serve as the final collimating and beam steering optic for the laser transmitter. Two lidar systems based on this technology have been designed, built, and successfully tested in atmospheric science applications. This technology will enable future spaceborne lidar missions by significantly lowering the size, weight, power requirement and cost of a large aperture, narrow field of view scanning telescope.     

The state of the art in asymmetric induction: the aldol reaction as a case study

This review highlights the achievements in asymmetric induction in the context of the aldol reaction during the years 2003–2007. While chiral auxiliary-mediated methods are the best understood and developed, catalytic methods based on chiral metal–ligand complexes and more recently organocatalysts promise to improve the efficacy and economics of asymmetric induction. This review provides a brief summary of work prior to 2003 on chiral auxiliaries, metal catalysts and organocatalysts, and then delineates the state of the art in each process. It appears that no one method of achieving asymmetric induction in the aldol reaction is universally superior.     

The determination of Miconazole and its related production impurities together with basic solution stability studies using a sub 2 μm chromatographic column

A selective and sensitive method for the analysis of Miconazole and its associated impurities is developed. The separation is carried out using a Thermo Scientific Hypersil Gold C18 Column (50 mm x 4.6 mm i.d., 1.9 μm particle size) with a mobile phase of acetonitrile-methanol-ammonium acetate (1.5 w/v) (30:32:38 v/v) at a flow rate of 2.5 mL/min and UV detection at 235 nm. The method is validated according to ICH guidelines with respect to precision, accuracy, linearity, specificity, robustness, and limits of detection and quantification. All parameters examined are found to be well within the stated guidelines. Naturally aged samples are also tested to determine sample stability. A profile of sample and impurity breakdown was presented. The analysis time was more than halved from just under 20 min (the current European Pharmacopeia Method) to under 8 min (developed method) and the method is applicable for assay and related substance determination.     

4-(2-Pyridylazo)-resorcinol as a possible analytical reagent for the colorimetric estimation of cobalt,lead, and uranium ,

4-(2-Pyridylazo)-resorcinol has been synthesized, and its uses as an analytical reagent for the colorimetric estimation of cobalt, uranium and lead have been investigated. It has been shown to be the most sensitive reagent for the colorimetric estimation of cobalt, the most sensitive watersoluble reagent for the colorimetric estimation of uranium, and the first published water-soluble reagent for the colorimetric estimation of lead.     

Synthetic magnetic opals

We present studies of novel nanocomposites of BiNi impregnated into the structure of opals as well as inverse opals. Atomic force microscopy and high resolution elemental analyses show a highly ordered structure and uniform distribution of the BiNi filler in the matrix. These BiNi-based nanocomposites are found to exhibit distinct ferromagnetic-like ordering with transition temperature of about 675 K. As far as we know there exists no report in literature on any BiNi compound which is magnetic.     

Ruthenium‐Catalyzed Reductive Coupling of 1,3‐Enynes and Aldehydes by Transfer Hydrogenation: anti‐Diastereoselective Carbonyl Propargylation

Under the conditions of ruthenium‐catalyzed transfer hydrogenation employing isopropanol as a source of hydrogen, isopropoxy‐substituted enyne 1 b and aldehydes 3 a – 3 l engage in reductive coupling to provide products of propargylation 4 a – 4 l with good to complete levels of anti‐diastereoselectivity. The unprotected tertiary hydroxy moiety of isopropoxy enyne 1 b is required to enforce diastereoselectivity. Deuterium‐labeling studies corroborate reversible enyne hydrometalation in advance of carbonyl addition. As demonstrated in the conversion of 4 f – h and 4 k to 5 f – h and 5 k , the isopropoxy group of the product is readily cleaved upon exposure to aqueous sodium hydroxide to reveal the terminal alkyne.     

Quality in clinical laboratory measurements

 Clinical chemistry deals with measurements and observations using samples from patients in order to supply clinicians with information to support their decisions in diagnosis and treatment. The discipline utilizes advanced chemical and biochemical methods and also sophisticated instrumentation which allows a high throughput. Clinical chemistry has a long tradition of quality assessment and improvement. The major tools have been proficiency testing or external quality assessment and internal quality control. Nowadays, total quality management has become widely recognized, and accreditation according to international, regional or national schemes has contributed to the design of quality systems and improvement of the reliability of results from clinical laboratories.