Schiff base adducts of hemoglobin. Modifications that inhibit erythrocyte sickling

Normal and sickle erythrocytes were exposed in vitro to millimolar concentrations of 31 different carbonyl compounds. Schiff base (imine) linkages were formed with amino groups of intracellular hemoglobin. Adducts were isolated by gel electrofocusing and could be dissociated by dialysis. Aromatic aldehydes proved more reactive than aliphatic aldehydes, and ketones were unreactive. The influence of various ring substituents on the reactivity of aromatic aldehydes was found to conform closely to traditional concepts regarding electronic and steric effects. Several of the aromatic aldehydes were shown to markedly increase the oxygen affinity of hemoglobins A and S. In particular, 2,4-dihydroxybenzaldehyde and o-vanillin, at concentrations of 5 mM, produced 2- to 3-fold reductions in the P50 (partial pressure of oxygen at half-saturation) of sickle hemoglobin in whole blood. Since low degrees of oxygen saturation promote erythrocyte sickling, compounds of this type significantly inhibit sickling at reduced partial pressures of oxygen.     

Thermodynamics of macromolecular systems

Summary From light scattering measurements in the system polystyrene-cyclohexane-acetone within the temperature range from 288 to 323 K it is concluded that the surface of the reduced chemical potential of the solvent as function of solvent composition and temperature exhibits the characteristics of true cosolvency. The influence of cyclohexane-acetone ratio on the temperature dependence of the corresponding enthalpy and entropy parameters is discussed. The cosolvency effects are evidenced also by studies of the STAUDINGER index at 34.5° C over the whole range of the ternary system.Properties of the binary solvent mixture cyclohexane-acetone, i. e. excess volume and viscosity, indicate that acetone clustering breaks down by dilution with cyclohexane. Consequently, the observed true cosolvency may be interpreted as caused by the combined action of cyclohexane and non-associated acetone.     

An Optimized Design of the Bearing in Machines for Ultrasonic Machining Processes

In high-power ultrasonic manufacturing processes, the design of the bearing of the components transmitting ultrasound is of particular importance, since the position of the nodal planes in the vibrating structure is altering as a consequence of changing coupling conditions during the process. A special bearing, which reduces the residual vibrations at the fixing ring by a system of several resonators, has been developed for the use in ultrasonic production processes, such as tube drawing and wire drawing but also drilling and welding. Since the transmitted longitudinal vibrations always involve radial components as well, the dynamic stiffness of the coupling on the interface between the components transferring energy and the components deleting vibration is very important. In the method described in this paper, an optimization of dynamic behavior is attained by stiffness-reduced coupling.     

Detrimental Effect of Unreacted PbI2 on the Long-Term Stability of Perovskite Solar Cells

Excess/unreacted lead iodide (PbI₂) has been commonly used in perovskite films for the state-of-the-art solar cell applications. However, an understanding of intrinsic degradation mechanisms of perovskite solar cells (PSCs) containing unreacted PbI₂ has been still insufficient and, therefore, needs to be clarified for better operational durability. Here, it is shown that degradation of PSCs is hastened by unreacted PbI₂ crystals under continuous light illumination. Unreacted PbI₂ undergoes photodecomposition under illumination, resulting in the formation of lead and iodine in films. Thus, this photodecomposition of PbI₂ is one of the main reasons for accelerated device degradation. Therefore, this work reveals that carefully controlling the formation of unreacted PbI₂ crystals in perovskite films is very important to improve device operational stability for diverse opto-electronic applications in the future.     

Channelling optics for high quality imaging of sensory hair

A long distance microscope (LDM) is extended by a lens and aperture array. This newly formed channelling LDM is superior in high quality, high-speed imaging of large field of views (FOV). It allows imaging the same FOV like a conventional LDM, but at improved magnification. The optical design is evaluated by calculations with the ray tracing code ZEMAX. High-speed imaging of a 2 × 2 mm(2) FOV is realized at 3.000 frames per second and 1 μm per pixel image resolution. In combination with flow sensitive hair the optics forms a wall shear stress sensor. The optics images the direct vicinity of twenty-one flow sensitive hair distributed in a quadratic array. The hair consists of identical micro-pillars that are 20 μm in diameter, 390 μm in length and made from polydimethylsiloxane (PDMS). Sensor validation is conducted in the transition region of a wall jet in air. The wall shear stress is calculated from optically measured micro-pillar tip deflections. 2D wall shear stress distributions are obtained with currently highest spatiotemporal resolution. The footprint of coherent vortical structures far away from the wall is recovered in the Fourier spectrum of wall shear stress fluctuations. High energetic patterns of 2D wall shear stress distributions are identified by proper orthogonal decomposition (POD).     

Degradation and possible carry over of feed DNA monitored in pigs and poultry

A possible carry over of foreign food DNA into the body after consumption was examined. After feeding pigs with conventional and recombinant (Bt-) maize, different body samples were investigated using DNA-extraction followed by PCR procedures to detect chloroplast genes of different length (199 bp and 532 bp), a maize-specific gene (zein) and a specific transgene present in Bt-maize (cryIa). Initially, a time-dependent degradation of feed DNA in the gastrointestinal tract of pigs was analysed within the juices from stomach and three parts of the small intestine (duodenum, jejunum, ileum). Subsequently, a possible transfer of residual chloroplast specific DNA as well as recombinant Bt-maize DNA fragments into different pig organs (blood, muscle, liver, spleen and lymph nodes) was examined. The suitability of the introduced DNA extraction procedure was verified through amplification of a universal gene (ubiquitin) demonstrating the successful PCR analysis within a range of 189-417 bp long DNA. Short chloroplast DNA fragments (199 bp) could be successfully amplified from the intestinal juices of pigs up to 12 h after the last feeding. In contrast, chloroplast-specific DNA was not found in any pig organ investigated so far. Specific gene fragments from the transgene maize (Bt-maize) were never detected in any pig sample. A field study examining supermarket poultry samples (leg, breast and wing muscle, stomach) led to frequent detections of the short chloroplast DNA fragment (199 bp). Furthermore, faint signals for the maize specific zein gene fragment were detected in these poultry tissues. Additional PCR examinations using unhatched chicken embryos provided the first indication that neither chloroplast nor maize genes are present endogenously within the wild-type poultry genome. Therefore, a transient transfer of short forage DNA into most poultry organs can be suspected.     

Changes in net portal nutrient flux in response to weaning transition and ionophore supplementation in dairy calves

Dairy calf weaning is associated with ketone concentrations that exceed the levels occurring in adults, and weaning represents a potential energy loss that may be mitigated by ionophore supplementation. To assess the effects of weaning and ionophore supplementation on net nutrient flux across portal-drained viscera (PDV) tissues in dairy calves, concentrations of glucose, acetoacetate (ACAC), β-hydroxybutyrate (BHBA), nonesterified fatty acids, volatile fatty acids, lactate, pyruvate, insulin, and glucagon and PDV flux rates were determined in Jersey bull calves (n = 19) at 35, 56, 84, and 112 d of age. Calves were randomly assigned at birth to either a commercial pelleted starter without (CON) or with lasalocid (TRT; 83 mg/kg of dry matter). Calves were fed only milk replacer from d 3 to 34 (d 3 to 20 = 454 g/d; d 21 to 34 = 56 g/d). After blood sampling on d 35, calves received replacer (d 35 to 41 = 45 g/d; d 42 to 48 = 22 g/d) and had free access to the CON or TRT starter, and from d 49 to 112 they received CON or TRT ad libitum. Catheters were implanted in the portal vein and in the mesenteric vein and artery between d 21 and 28. Blood flow was measured by continuous infusion of p-aminohippurate into the mesenteric vein. Six serial samples were taken at 30-min intervals from the arterial and portal vein catheters simultaneously. Portal blood flow increased with age but did not differ between CON and TRT calves. Glucose was released preweaning and was extracted postweaning by PDV, but was not affected by ionophore. The portal flux of nonesterified fatty acids was not different from zero during any of the 4 sample ages. Fluxes of ACAC and BHBA in CON and TRT calves went from no measurable flux preweaning to a postweaning PDV release that peaked at d 84, but the d-84 release of ACAC and BHBA was lower in TRT calves. The portal flux of volatile fatty acids increased with age, and PDV release of both butyrate and propionate was lower at d 84 in TRT than in CON calves. However, TRT calves had a greater PDV release of lactate on d 84, partially compensating for the lower release of propionate. Glucagon was greater in CON than in TRT calves at d 84 and could be a response to the elevated ketogenesis observed in CON calves during this period. Changes in the metabolic profile and nutrient flux of transition calves were demonstrated in response to weaning and ionophore supplementation. Inclusion of an ionophore appeared to moderate alimentary output at a postweaning period (d 84) at which ketone concentrations have the potential to exceed the whole animal capacity for utilization.     

Piezoelectric actuator design for ultrasonically assisted deep hole drilling

From different chipping machining processes it is known that a superposition of the cutting kinematics with additional vibration energy increases material removal rate and tool life. Concerning the deep drilling process in the scope of smallest diameters from 0.9 to 6 mm insights to this so called hybrid processes are still awaited. Preliminary investigations indicated that here is high, so far unused potential. The goal of current research is an increase in effectiveness of the deep hole drilling process by superimposing additional vibration energy in ultrasonic frequency range by means of a piezoelectric transducer and low-frequency vibrations in the range of acoustic frequencies as well. Positive effects can appear in a couple of areas, e.g. achievable surface quality, feeding force, drilling torque, shape and length of chips, feasibility of machining ceramic materials and tool wear. This paper describes mainly the ultrasound conform design of the vibration unit. Furthermore issues of contactless energy transfer into a rotating tool and model based design of piezoelectric transducers will be addressed.     

Positron spectroscopy in elastic and dissipative heavy ion collisions

A new magnetic transport system, the Tori spectrometer, which is able to measure positrons and electrons simultaneously, has been used to study the dynamics of collisions between very heavy ions via their influence on the positron and δ-electron spectra. While these spectra obtained in coincidence to elastic scattering agree well with theory based on pure Rutherford trajectories, those observed in coincidence to dissipative collisions can only be described by calculations taking into account a time delay in the collision process. A quantitative analysis gives an estimation for the nuclear contact time in the U + U collision.