3‐Formyl­phenyl­boronic acid

The mol­ecule of the title compound, C₇H₇BO₃, is planar, and the bond lengths and angles are typical. The formyl group is essentially coplanar with the benzene ring but does not influence significantly the distortion of the ring, although the formyl group does have a strong influence on the crystal packing. The geometry of the boronic acid group is typical. In the crystal structure, the mol­ecules are linked by O—H⋯O hydrogen bonds.     

Cavitation and morphological changes in polypropylene deformed at elevated temperatures

Polypropylene (PP) thick films were subjected to tensile drawing at various temperatures from the room temperature to 100 °C. Morphological alterations during drawing were followed by wide‐angle X‐ray scattering, small‐angle X‐ray scattering, and scanning electron microscopy (SEM) of sectioned and etched samples, volume strain measurement, and light transparency measurement at various level of strain. The morphological observations were paralleled with stress–strain determination. Samples drawn at 25 and 40 °C undergo severe cavitation contributing to their volume increase up to 90–95%. The volume increase contributes greatly to the engineering strain. PP drawn at 70 and 100 °C does not cavitate. At the strain up to 1.2, a high lamellae orientation is observed in SEM, whereas the 2D WAXS patterns show in contrary circular diffraction rings indicating low orientation of crystals. The rotation of lamellae toward drawing direction is associated with reverse rotation of chains in crystals due to fine chain slips. These two rotations in opposite directions counterbalance resulting in a much weaker crystal orientation than expected from the SEM images. Noncavitating samples retain their translucency up to a high strain. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1271–1280, 2010     

A dilute-limit heat of solution of molybdenum in iron studied with 57Fe Mössbauer spectroscopy

The room temperature Mössbauer spectra of ⁵⁷Fe were measured for iron-based solid solutions Fe_1???x Mo _x with x in the range 0.01?≤?x?≤?0.05. The obtained data were analysed in terms of the binding energy E _b between two molybdenum atoms in the studied materials using the extended Hrynkiewicz–Królas idea. It was found that the energy is positive or Mo atoms interact repulsively. The extrapolated value of E _b for x?=?0 was used for computation of the dilute-limit heat of solution of Mo in Fe. The obtain result was compared with both, the corresponding values given in the literature which were calculated theoretically on the basis of the simple embedded-atom model, as well as with the value resulting from the cellular atomic model of alloys by Miedema. The comparison shows that our findings are in a qualitative agreement with the Miedema’s model predictions and they are at variance with the theoretical computations mentioned above.     

On the improvement of expectation values in the uncoupled SCF and HF perturbation theories

The exact derivation of the formula for the first-order ‘correlation’ correction to the second-order uncoupled Hartree-Fock energies, computed with approximate Hartree-Fock orbitals, is presented. A comparison with the corresponding formula derived under the assumption of the exact solution of the Hartree-Fock equations indicates that also the second-order perturbed orbitals do contribute. However, their contribution can be expressed in terms of the first-order correction to the SCF orbitals which accounts for the difference between the Hartree-Fock and SCF solution. These additional terms can be either positive or negative and can influence significantly the final result for the correlation-corrected second-order energies.     

Quality Assessment of Wild and Cultivated Green Tea from Different Regions of China

Natural products have always enjoyed great popularity among consumers. Wild tea is an interesting alternative to tea from intensive plantations. The term “wild tea” is applied to many different varieties of tea, the most desirable and valued of which are native or indigenous tea plants. Special pro-health properties of wild tea are attributed to the natural conditions in which it grows. However, there are no complex studies that describe quality and health indicators of wild tea. The aim of this research was to evaluate the quality of wild and cultivated green tea from different regions of China: Wuzhishan, Baisha, Kunlushan, and Pu’Er. The assessment was carried out by verifying the concentration of selected chemical components in tea and relating it to the health risks they may pose, as well as to the nutritional requirements of adults. Wild tea was characterized by higher micronutrient concentration. The analyzed teas can constitute a valuable source of Mn in the diet. A higher concentration of nitrates and oxalates in cultivated tea can be associated with fertilizer use. The analyzed cultivated tea was a better source of antioxidants with a higher concentration of caffeine. There were no indications of health risks for wild or cultivated teas.     

Prediction of physical and chemical qualities of crude-oil using statistical time series analysis

An application of a statistical time series analysis method is given for the interpretation of physical and chemical qualities of crude-oil samples taken from two oil-fields in Poland. The analytical data was gathered in the years 1995–1999, the information being collected once a month. Randomly selected crude-oil samples were examined in several analytical laboratories. For each sample examined, the following chemical-physical parameters were defined: date, source of the sample, specific gravity, density, colour, relative viscosity, viscosity, kinematic viscosity, drip point, setting point, etc. The data obtained played a decisive role in classifying the samples of crude-oil and in forecasting the properties of crude-oil that will be obtained from the mines in the future. To process the data obtained, the STATISTICA programme was used. It contains a module for time series analysis and for graphical presentation of the results.     

A Study of the Lipophilicity of Amide Derivatives of α-(1,2,3,4-Tetrahydroisoquinolin-2-yl)-γ-hydroxybutyric Acid by Use of RP-TLC and Calculation

JPC – Journal of Planar Chromatography – Modern TLC - Evaluation of the lipophilicity of derivatives of N-benzylamides and N-phenylethylamides of...     

Some properties of milled vanadium phosphates

Mechanochemical modification of vanadium phosphates doped with Bi, Zr, Mo has been studied. Milled samples have been investigated by means of XRD, DTA-TG, FTIR, nitrogen adsorption, electrokinetic measurements. It was found that phase composition of the phosphates does not change upon the mechanochemical modification process. Milling in water causes formation of porous materials. Modification of surface results in changes of the electrokinetic and adsorption properties of the milled samples.