Hydrogen Bonding in Thermoplastic Polyurethane Elastomers:IR Thermal Analysis

The hydrogen bond percentage and its temperature dependence of the three TPU samples synthesized from polytetrahydrofuran, 4,4'-diphenylmethane diisocyanate, N -methyl diethanol amine or 1,4-butane diol were studied by means of IR thermal analysis. The enthalpy and the entropy of the hydrogen bond dissociation were determined by the Van't Hoff plot.

A Novel 2D Architecture from Bismuth and Flexible Ligand N,N'-Diacetic Acid Imidazolium Chloride

A new compound {[Bi（trans-DAM）（cis-DAM）（H2O）]NO3·H2O}n 1 derived from bismuth and the flexible ligand N,N＇-diacetic acid imidazolium chloride （H2DAMCl） was obtained by hydrothermal synthesis and characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic P21/c space group with a = 9.2298（18）, b = 13.339（3）, c = 17.090（3） , β = 105.38（2）°, V = 2028.7（7）A^3, Z = 4, C14H18N5O13Bi, Mr = 673.31, Dc = 2.204 g/cm^3, F（000） = 1296, μ = 8.772 mm-1, the final R = 0.0472 and wR = 0.1441 for 4129 observed reflections （I 〉 2σ（I））. In 1, the carboxylic groups from DAM- ligands adopt a cheating mode to link bismuth ions to form a 2D sheet network. These sheets are further connected by hydrogen bonding interactions to give an interesting 3D supramolecular framework. 2D correlation analysis of IR of 1 with thermal and magnetic perturbation was introduced to ascertain the characteristic adsorption of the groups overlapped in the 1D IR spectrum. Additionally, compound 1 exhibits fluorescent emission at room temperature.

VINYL RADICAL POLYMERIZATION INITIATED WITH CERIC ION AND N-(SUBSTITUTED PHENYL) ACETAMIDE SYSTEMS

The polymerization of acrylamide (AAM)in H_2O/DMF or in H_2O/CH_3CN mixed solvent initiated with ceric ion (Ce^(4+) )/N-(substituted phenyl)-acetamide systems have been studied. The redox polymerization was revealed by the low value of overall activation energy (E_α) of AAM polymerization using ceric ion/N-(substituted phenyl) acetamide system as an initiator. The end group of polymer formed was detected by IR spectrum analysis method, it revealed the presence of N-(m-acetoxy-methylphenyl) acetamide (m-AAe) moiety end group in the polymer obtained with ceric ion/m-AAe initiation system.

An examination of handwritten signatures forged using photosensitive signature stamp

Signature examination is the most common examination performed by any document examiner.Determination of the authenticity of a handwritten signature on a questioned document is an important task for forensic document examiners in the forensic science field.As a result of continuous developments in technology,a signature stamp can now be created using a photosensitive seal to enable the reproduction of a handwritten signature.These stamps are commonly used in China and several other countries.In this study,10 types of black photosensitive stamp-pad ink,10 brands of fountain pen ink,15 types of black gel ink and six types of black erasable gel ink found on the Chinese domestic market were collected and 10 photosensitive signature stamps were created using the signatures of 10 people.Microscopic analysis,infrared(IR)and fluorescence analyses and microspectrophotometry(MSP)techniques were used to examine the resulting photosensitive signature stamp impressions when applied to printing papers,writing papers and invoice papers.By comparing the printing and spectral characteristics of the photosensitive signature stamp impressions with those of the signatures executed using the fountain pens,gel pens and erasable gel pens,it was possible to determine whether each signature was written or stamped using a photosensitive signature stamp.To validate these results,a 96.7%absolute accuracy and a 99.3%detection rate were achieved over a total of 150 blind tests conducted by five forensic document examiners,thus demonstrating that a combination of the four analysis methods used in this work can provide a more scientific approach and improve the accuracy and the detection rate of the examination process.