An integrated 8-12 GHz fractional-N frequency synthesizer in SiGe BiCMOS for satellite communications

We present an integrated fractional-N low-noise frequency synthesizer for satellite applications. By using two integrated VCOs and combining digital and analog tuning techniques, a PLL lock range from 8 to 12 GHz is achieved. Due to a small VCO fine tuning gain and optimized charge pump output biasing, the phase noise is low and almost constant over the tuning range. All 16 sub-bands show a tuning range above 900 MHz each, allowing temperature compensation without sub-band switching. This makes the synthesizer robust against variations of the device parameters with process, supply voltage, temperature and aging. The measured phase noise is ?87 dBc/Hz and ?106 dBc/Hz at 10 kHz and 1 MHz offset, respectively. In integer-N mode, phase noise values down to ?98 dBc/Hz at 10 kHz and ?111 dBc/Hz at 1 MHz offset, respectively, were measured.     

Selectively Promoting or Preventing Osteoblast Growth on Titanium Functionalized with Polyelectrolyte Multilayers

Titanium plays an important role in medical applications, such as hip joint implants or fixation plates. These implants must perform differently depending on their clinical application. In particular, the osseointegrative properties required of the implant vary with clinical application. The present work is aimed at the functionalization of titanium surface using polyelectrolyte multilayers consisting of natural biopolymers and testing their cell adhesive properties with respect to the osseointegration capacity. Multilayered coatings were created from chitosan (Chi), hyaluronic acid (HA), and gelatine (Gel) through layer‐by‐layer deposition. Cell adhesion, proliferation, and viability were tested in vitro with the human osteoblast cell line CAL‐72 at timescales up to 7 d. Two multilayer coatings consisting of alternated chitosan/gelatin or chitosan/hyaluronic acid layers with the outmost layer of gelatin (Chi/Gel) or hyaluronic acid (Chi/HA), respectively, were tested. The experimental results showed that surfaces functionalized with Chi/Gel and Chi/HA multilayers demonstrated a good initial adhesion of osteoblasts. After 4 d culturing, osteoblast cells were almost completely detached from the substrates functionalized with Chi/HA multilayers. In contrast to Chi/HA, the proliferation of osteoblasts on substrates with Chi/Gel multilayer coatings was statistically significantly higher compared to the control titanium. We have shown that the growth of osteoblasts can be enhanced or completely prevented on a titanium surface functionalized with polyelectrolyte multilayers consisting of natural biopolymers, as desired. Both multilayer coatings, Chi/Gel and Chi/HA, have potential for applications in the field of titanium implants, where rapid osseointegration is essential, and/or where no ingrowth of the implant is desired, respectively.     

A Study on the Feasibility of Measuring the Emissivity with the Laser-Flash Method

The laser-flash method is a fast, widely used and well established technique to measure the thermal diffusivity. Since its introduction in the 1960s, it was proposed to expand this technique to the measurement of heat capacity and emissivity. Currently, the measurement of spectral emissivity at high temperatures is connected with relatively large uncertainties, although the spectral emissivity is an essential parameter for applications, e.g., in the lamp industry and fusion research. In this work, a theoretical study is presented on the possibility of emissivity measurements using the laser-flash method. Two mathematical approaches are discussed which solve the problem, that a measured temperature rise—necessary to calculate the emissivity—itself depends on the emissivity. It is shown that both methods have a negligible arithmetic error, making them applicable to be used in future work.     

Gamma irradiation of cowpea (Vigna unguiculata L. Walp) flours and pastes: Effects on functional,thermal and molecular properties of isolated proteins

In a previous study irradiation of cowpea flours and pastes at medium (10 kGy) and high (50 kGy) doses resulted in significant changes in protein-related functional properties. To understand some of the effects of gamma irradiation on cowpea proteins in particular, we isolated proteins from cowpea flours (FPC) and pastes (PPC) treated with gamma irradiation at 2, 10, and 50 kGy and analyzed their functional, thermal and molecular properties. Nitrogen solubility index of both FPC and PPC decreased, whereas oil absorption and emulsion capacities increased significantly with increasing irradiation dose. Differential scanning calorimetry showed decreases in transition temperatures (T_d) and enthalpies (ΔH), indicating a progressive denaturation of cowpea proteins with increasing irradiation. Size exclusion HPLC revealed increases in protein molecular weights, probably due to protein–protein cross-linking with irradiation in a dose-dependent manner. Reducing SDS-PAGE of FPC and PPC samples seems to suggest that the contribution of disulphide bonds to irradiation-induced cowpea protein–protein cross-linking is small.     

Local tissue necrosis after appendicitis in pregnancy (author's transl)

A local necrosis of the abdominal wall in the previous appendectomy scar was observed in a Gravida 3 at 32 weeks gestation following appendectomy for acute appendicitis. The findings and the clinical course were suspicious of a condition resembling local Shwartzman Phenomenon.     

Relation of two Piagetian stage transitions to IQ.

An analysis of psychometric and Piagetian assessments of children's mental ability led to the prediction that the relation between these 2 kinds of assessments diminishes as children advance in age and stage level. The prediction was confirmed. A high correlation was found between MA (WISC scores) and progression toward Piaget's stage of concrete operations among 52 middle-class 6-8 yr olds, but the correlation was nonsignificant between MA and progression toward Piaget's stage of formal operations among 56 middle-class 10-12 yr olds. Alternative explanations of results are considered, and additional evidence is discussed which suggests that, although IQ is not related to the emergence of formal operations in preadolescence, the full development and/or maintenance of formal functioning during adulthood bears a relation to those educational and cultural advantages associated with higher IQs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ermittlung der mittleren Temperatur der Gießstrahlumgebung bei temperaturabhängigen Stoffgrößen

Entkopplung der Temperaturfelder von den Geschwindigkeits- und Konzentrationsfeldern bei der Untersuchung des Stoffaustausches zwischen Gießstrahl und Umgebung durch Verwendung von Stoffparametern, die bei einer bestimmten Temperatur, der mittleren Temperatur, berechnet werden. Güte dieser Näherung abhängig von der Wahl der mittleren Temperatur. Unter Berücksichtigung des Einflusses der Strömung Ableitung einer mittleren Temperatur, in die die mittlere Grenzschichtdicke der Strahlumgebung eingeht und die die Nachteile der Filmtemperatur vermeidet.     

Production,Purification, and Characterization of Thermoanaerobacterium thermosaccharolyticum Glucoamylase

Glucoamylase from Thermoanaerobacterium thermosaccharolyticum ATCC 7956 (DSM 571) was produced in extracellular form. It was purified to homogeneity by two separate methods, one with two chromatographic steps and the other with three. This glucoamylase is closely related to glucoamylases from Clostridium sp. G0005 and T. thermosaccharolyticum DSM 572. Activities and K_M values with maltose substrate are less than one‐tenth and about fourfold, respectively, those of Aspergillus niger glucoamylase. T. thermosaccharolyticum glucoamylase is about twenty times as thermostable as A. niger glucoamylase and its optimal pH is somewhat higher at 4.9; however, it is produced in much lower activities. Sorbitol strongly stabilizes A. niger glucoamylase.     

Biodegradability of 14C-labeled antibiotics in a modified laboratory scale sewage treatment plant at environmentally relevant concentrations

For all new pharmaceuticals, an environmental risk assessment (ERA) has to be performed according to guidelines developed by the European Medicines Evaluation Agency. An important factor of this procedure is the assessment of the predicted environmental concentration in the aquatic environment, which is significantly influenced by the biodegradability of pharmaceuticals in sewage treatment plants. Established standardized methods for determining biodegradation under laboratory conditions apply to substance concentrations, which are much higherthan those expected in reality. Against this background, the laboratory scale sewage treatment plant (LSSTP), as described by the Organisation for Economic Cooperation and Development (OECD) Guideline No. 303A, was modified to construct a lossless system, which allows laboratory testing at realistic concentrations. To verify the experimental setup, the antibiotics benzylpenicillin, ceftriaxone, and trimethoprim were tested at low concentrations (microg/L) using 14C-labeled compounds. The results show that approximately 25% of benzylpenicillin was mineralized, whereas ceftriaxone and trimethoprim were not mineralized at all. Due to the high total recoveries of added radioactivity (> or =95%) and the fact that the findings comply with available literature data, the lossless operation of the test system could be proved. Consequently, the modified LSSTP is a suitable tool to determine more realistic biodegradation data required for the exposure assessment within the scope of an ERA for pharmaceuticals.