The shape-conformal stamp with active surface microstructures was used for programmable and scalable transfer printing.

This article highlights recent advances in the development of transition metal-based catalysts for formaldehyde oxidation, particularly the enhancement of their catalytic activity for low-temperature oxidation. Various factors that enhance low-temperature activity are reviewed, such as morphology and tunnel structures, synthesis methods, specific surface area, amount and type of active surface oxygen species, oxidation state, and density of active sites are discussed. In addition, catalyst immobilization for practical air purification, reaction mechanism of formaldehyde oxidation, and the reaction parameters affecting the overall efficiency of the reaction are also reviewed.

An environmentally friendly reversed-phase HPLC method for simultaneous determination of creatinine and uric acid in human urine samples has been developed. Human urine samples were pretreated by dilution, protein precipitation, centrifugation and filtration, followed by HPLC separations using a reversed-phase C18 column with an aqueous mobile phase of phosphate buffer. The retention loss of a C18 column when using the highly aqueous mobile phases was avoided by employing a gradient elution using a small volume (<0.23 mL) of acetonitrile and phosphate buffer at pH 4.75. This developed method provides a simple, rapid separation and sensitive detection for the species of interest in 10 min with UV detection at 205 nm. Quantitation was carried out by relating the peak areas of the identified compounds to that of hypoxanthine as an internal standard. The detection limits for creatinine and uric acid were 0.045 and 0.062 µg mL-1, respectively. The recoveries of the standards added to urine samples were 87.3 - 102.2% for creatinine and 97.3 - 108.6% for uric acid, and the relative standard deviation for both analytes was less than 1.0%. This method has been successfully applied to estimating of creatinine and uric acid in human urine.