Zur Analyse von Milchsäure-Glykolsäure-Copolyestern

Für L-(–)-Lactid-Glykolid-Copolyester (3) wurden drei voneinander unabhängige Analysenmethoden zur Bestimmung der Copolymeren-Zusammensetzung ausgearbeitet. Die ¹H-NMR-Spektroskopie wurde für Copolyester mit Lactid-Gehalten über 10 Gew.-% erfolgreich angewandt, nachdem mit Trifluoressigsäure ein geeignetes Lösungsmittel gefunden war. Insbesondere für die praktisch interessanten Materialien mit kleinem Lactid-Anteil, wie z. B. resorbierbares chirurgisches Nahtmaterial, eignen sich die Messung der optischen Rotation sowie eine chemische Methode, die auf der quantitativen Bestimmung der Milchsäure nach vorhergehender alkalischer Totalhydrolyse beruht.     

Size distribution of wastewater COD fractions as an index for biodegradability

The study proposes direct particle size measurement by sequential filtration and ultrafiltration as a convenient method for wastewater characterization for appropriate treatment technology. It also explores the correlation between particle size distribution (PSD) and chemical oxygen demand (COD) fractionation, as an index for biological treatability. Profiles obtained through PSD-based COD fractionation serve as the fingerprints for wastewaters, and as demonstrated in this study, reflect different pictures for textile wastewater and domestic sewage. PSD-based COD fractionation profiles identify the soluble range below 2 nm as the size interval housing both the soluble inert COD initially present in the wastewater and soluble inert microbial products generated during biological treatment, as also supported by the metabolic fractionation attained through respirometric analyses. Moreover, PSD-based color profiling offers a good index for the fate of biologically resistant chemicals passing through biological treatment. Compatible results obtained from comparative evaluation of PSD-based COD and color profiles provide useful information on the biodegradability of the textile wastewater studied.     

Poly(3-hydroxyalkanoate)s: Diversification and biomedical applications: A state of the art review

Biomaterials have played an important role in the treatment of disease and the improvement of health care. Synthetic and naturally occurring biodegradable and biocompatible polymers have been used as biomaterials. Polyhydroxyalkanoates (PHAs) are promising materials for biomedical applications because they are biodegradable, non-toxic and biocompatible. We will shortly summarize the modification reactions, which include functionalization and grafting reactions, to improve the mechanical, thermal and hydrophilic properties of PHAs. The use of the modified PHAs in numerous biomedical applications, such as sutures, cardiovascular patches, wound dressings, scaffolds in tissue engineering, tissue repair/regeneration devices, drug carriers will be discussed in this review.     

In situ investigation of phosphonate retarder interaction in oil well cements at elevated temperature and pressure conditions

The effect of a high-performance retarding additive in oil well cements was investigated under elevated temperature (165°C) and pressure (1000 psi) conditions via in situ synchrotron-based X-ray diffraction (XRD) and quasielastic neutron scattering (QENS) techniques. Under these temperature and pressure conditions, crystalline calcium silicate hydrates (C–S–H) are formed through the cement hydration process. From in situ XRD experiments, the retardation effect was observed by a change in the rate of the appearance of 11 Å tobermorites as well as a change in the rate of the α-C₂SH generation and depletion. QENS analysis revealed that the retardation effect was related to the non-conversion of free water to chemical and constrained water components. A high presence of free water components was attributed to a decrease in 11 Å tobermorites along with slower consumption of the quartz and portlandite phases. Furthermore, QENS results infer that the water molecules experienced confinement in the restricted pore spaces. The retarder inhibited this initial water confinement by slowing the bulk diffusion of free water in the confined region.     

Effect of the type of frying oil on volatile compounds of goatfish (Upeneus pori) during cold storage

The effect of different types of oil (sunflower, soybean, corn and canola oil) on the volatile formation of fried goatfish (Upeneus pori) during refrigerated (2 °C) storage period were assessed in this study. When using the SPME technique, forty‐three compounds were detected. Among the detected compounds twelve aldehydes, nine alcohols, nine acids, three ketones, four amines and seven other compounds were found in raw and fried goatfish during refrigerated storage periods. Frying with different types of oil had significant influence on the volatile compounds of goatfish. However, considerable differences observed in the formation of some volatile compounds depending on type of frying oil. It was also concluded that, changes in volatile compounds during cold storage periods were not good spoilages markers for fried goatfish.     

Millimeter-wave antenna of a travelling-wave long sinusoidal slot in the broad face of a rectangular waveguide

A travelling-wave long sinusoidal slot in the broad face of a millimeter-wave (Ka-Band) rectangular waveguide is investigated. Similarities and differences with a same-shaped slot, but in the narrow face of the waveguide, which was investigated in a former study [1], are also discussed. It is observed that the most important difference between two antenna structures is the applied analytical model. It is found in measurements that the antenna with a broad face can only be described by an electric current model unlike the antenna with a narrow face where the magnetic current model agrees with measurements. In experimental study, some antenna parameters of the structure are demonstrated. The sinusoidal slot antenna investigated in this study has also a cross-polarized beam like the one in the narrow face of rectangular waveguide and a similar metallic grid polarizer is used like in the previous study to suppress this cross polarized beam. A suppression level up to 12 dB is reached. Antenna efficiency is calculated using S-parameters measurement and a remarkable increment is obtained after the polarizer is applied.     

Preconcentration and determination of copper and cadmium ions with 1,6-bis(2-carboxy aldehyde phenoxy)butane functionalized Amberlite XAD-16 by flame atomic absorption spectrometry

A new chelating resin, covalently linked 1,6-bis(2-carboxy aldehyde phenoxy)butane with the Amberlite XAD-16 was synthesized and used for preconcentration of Cu(II) and Cd(II) prior to their determination by flame atomic absorption spectrometry (FAAS). It was characterized by elemental analyses and Fourier Transform Infrared Spectroscopy (FT-IR). Cu(II) and Cd(II) ions were quantitatively preconcentrated on minicolumn loaded with synthesised resin at pH 4.00 and 6.00, respectively. They were eluated with 5 mL of 0.5 mol L⁻¹ HCl. Recoveries of Cu(II) and Cd(II) were found to be 100 ± 2.15, 100 ± 1.40 (N = 5), the limits of detection of Cu(II) and Cd(II) in the determination by FAAS (3s, N = 20) were found to be 0.33 and 1.19 μg L⁻¹, respectively. The effect of foreign ions on the recovery has been investigated. The proposed method has been applied for the determination of Cu(II) and Cd(II) ions to the real samples collected from Tigris river water in Diyarbak?r and Elaz?? cities in Turkey. Standard addition method and analysis of the certified reference material (NCS-DC 73350) was employed to check the accuracy of the method.