A highly stable sodium solid-state electrolyte based on a dodeca/deca-borate equimolar mixture

Na₂(B₁₂H₁₂)_0.5(B₁₀H₁₀)_0.5, a new solid-state sodium electrolyte is shown to offer high Na⁺ conductivity of 0.9 mS cm⁻¹ at 20 °C.

Di-hydrogen contact induced lattice instabilities and structural dynamics in complex hydride perovskites

The structural phase transitions occurring in a series of perovskite-type complex hydrides based on the tetrahydroborate anion BH4(-) are investigated by means of in situ synchrotron x-ray powder diffraction, vibrational spectroscopy, thermal methods and ab initio calculations in the solid state. Structural dynamics of the BH4 anion are followed with quasi-elastic neutron scattering. We show that unexpected temperature-induced lattice instabilities in perovskite-type ACa(BH4)3 (A = K, Rb, Cs) have their origin in close hydridic di-hydrogen contacts. The rich lattice dynamics lead to coupling between internal B-H vibrations and phonons, resulting in distortions in the high-temperature polymorph that are identical in symmetry to well-known instabilities in oxide perovskites, generally condensing at lower temperatures. It is found that anion-substitution BH4(-) <-> (X = Halide) can relax distortions in ACa(BH4)3 by eliminating coulomb repulsive H(-)···H(-) effects. The interesting nature of phase transition in ACa(BH4)3 enters an unexplored field of weak interactions in ceramic-like host lattices and is the principal motivation for this study. Close di-hydrogen contacts suggest new concepts to tailor crystal symmetries in complex hydride perovskites in the future.

Über die Reaktion von Vanillin mit phenolischen Verbindungen / Concerning the Reaction of Vanillin with Phenolic Compounds

Electron densities at the nucleus of several simple phenols and plant phenols such as catechin and quercetin are calculated by the HMO-method.

We found a correlation between the maximum of the electron density at the nucleus and the extinction value of the reaction product with vanillin. With the exception of quercetin an explanation is given by the HMO-calculation. Investigations into the structure of the reaction products have been carried out.

Hydrogen-fluorine exchange in NaBH4-NaBF4

Hydrogen-fluorine exchange in the NaBH4-NaBF4 system is investigated using a range of experimental methods combined with DFT calculations and a possible mechanism for the reactions is proposed. Fluorine substitution is observed using in situ synchrotron radiation powder X-ray diffraction (SR-PXD) as a new Rock salt type compound with idealized composition NaBF2H2 in the temperature range T = 200 to 215 °C. Combined use of solid-state (19)F MAS NMR, FT-IR and DFT calculations supports the formation of a BF2H2(-) complex ion, reproducing the observation of a (19)F chemical shift at -144.2 ppm, which is different from that of NaBF4 at -159.2 ppm, along with the new absorption bands observed in the IR spectra. After further heating, the fluorine substituted compound becomes X-ray amorphous and decomposes to NaF at ~310 °C. This work shows that fluorine-substituted borohydrides tend to decompose to more stable compounds, e.g. NaF and BF3 or amorphous products such as closo-boranes, e.g. Na2B12H12. The NaBH4-NaBF4 composite decomposes at lower temperatures (300 °C) compared to NaBH4 (476 °C), as observed by thermogravimetric analysis. NaBH4-NaBF4 (1:0.5) preserves 30% of the hydrogen storage capacity after three hydrogen release and uptake cycles compared to 8% for NaBH4 as measured using Sievert's method under identical conditions, but more than 50% using prolonged hydrogen absorption time. The reversible hydrogen storage capacity tends to decrease possibly due to the formation of NaF and Na2B12H12. On the other hand, the additive sodium fluoride appears to facilitate hydrogen uptake, prevent foaming, phase segregation and loss of material from the sample container for samples of NaBH4-NaF.

Electron-phonon interaction and charge carrier mass enhancement in SrTiO3

We report a comprehensive THz, infrared and optical study of Nb-doped SrTiO3 as well as dc conductivity and Hall effect measurements. Our THz spectra at 7 K show the presence of an unusually narrow (<2 meV) Drude peak. For all carrier concentrations the Drude spectral weight shows a factor of three mass enhancement relative to the effective mass in the local density approximation, whereas the spectral weight contained in the incoherent midinfrared response indicates that the mass enhancement is at least a factor two. We find no evidence of a particularly large electron-phonon coupling that would result in small polaron formation.

[Comparability of various measurement methods in nasal provocation with allergens]

Defined criteria for nasal provocation exist only for the anterior Rhinomanometrie (aRM). During the last years there are other techniques for nasal provocation in use. In this study the new instruments were compared with the established aRM. We examined 14 patients with perennial rhinitis. All showed positive skin test and RAST against D. pteronyssinus. The controls were 13 atopic patients sensitized against pollen but not against D. pteronyssinus and 20 healthy volunteers. All subjects underwent nasal provocation with D. pteronyssinus. On the first day the provocation was unilateral. The instruments were the aRM, the Oscilloresistometry (ORM), the Peak Nasal Inspiratory Flowmeter (PNIF) and the Acoustic Rhinometry (Rhinoklack). On the second day the provocation was bilateral with ORM and PNIF. First we determined the limits for separation between a positive and negative nasal provocation test for the different instruments. Then we calculated the sensitivity and specificity for the instruments. By unilateral provocation there was a good sensitivity for all devices. The specificity was very good with the aRM, ORM and PNIF. In conclusion the PNIF is as good as the other instruments, but the Rhinoklack was less specific than the others.

[Experiences with the psychometric system combitest in the evaluation of the postnarcotic arousal period]

Since the introduction of new German health legislation, operations formerly performed on an in-patient basis have been transferred to the out-patient sector. Due to this development evaluating the postnarcotic arousal period has become increasingly important. Vigilance, reactivity and state of health determine a patient's well-being and time of discharge after an operation and consequently influence economical and legal issues. Former studies investigating the arousal period have mainly focused on patient interviews and assessment of patients by staff. The aim of our study was to objectivize postnarcotic vigilance and reactivity (critical flicker fusion frequency and multiple choice reaction) using neurophysiological monitoring (psychometric system Combitest 2: CFF, EWR, MWR). The applied methods have been defined as valid, reliable and sensitive tools to investigate this question. Inter-individual and gender-specific differences as well as variations due to the type of anaesthetic employed can be detected. The study participants assessed the test battery's practicability and overall described this method as easy to use. Vigilance (CFF), basic and complex sensomotor reactivity (performance in simple and multiple choice tests) were restored after a postanaesthetic phase of 90 minutes (narcotics applied: isofluran and propofol). The results show that the use of modern anaesthetics does not justify the current medical and legal claim to 6 hours of postanaesthetic observation. The computer-supported psychometric system Combitest 2 has recently been used to assess the arousal phase after application of different types of anaesthetical procedures (TIVA, volatile, balanced) and has been found to be superior to parameters traditionally used to assess discharge criteria (time until patient opens eyes, orientation concerning time and location, time spent in postanaesthetic recovery room). Besides employing our study methods, subjective factors such as well-being and pain sensation should also be evaluated when determining the time of a patient's discharge.

Magnesium-adenosine diphosphate binding sites in wild-type creatine kinase and in mutants: role of aromatic residues probed by Raman and infrared spectroscopies

Two distinct methods were used to investigate the role of Trp residues during Mg-ADP binding to cytosolic creatine kinase (CK) from rabbit muscle: (1) Raman spectroscopy, which is very sensitive to the environment of aromatic side-chain residues, and (2) reaction-induced infrared difference spectroscopy (RIDS) and photolabile substrate (ADP[Et(PhNO(2))]), combined with site-directed mutagenesis on the four Trp residues of CK. Our Raman results indicated that the environment of Trp and of Tyr were not affected during Mg-ADP binding to CK. Analysis of RIDS of wild-type CK, inactive W227Y, and active W210,217,272Y mutants suggested that Trp227 was not involved in the stacking interactions. Results are consistent with Trp227 being essential to prevent water molecules from entering in the active site [as suggested by Gross, M., Furter-Graves, E. M., Wallimann, T., Eppenberger, H. M., and Furter, R. (1994) Protein Sci. 3, 1058-1068] and that another Trp could in addition help to steer the nucleotide in the binding site, although it is not essential for the activity of CK. Raman and infrared spectra indicated that Mg-ADP binding does not involve large secondary structure changes. Only 3-4 residues absorbing in the amide I region are directly implicated in the Mg-ADP binding (corresponding to secondary structure changes less than 1%), suggesting that movement of protein domains due to Mg-nucleotide binding do not promote large secondary structure changes.

[Humidification and heating of anesthetic gases during pediatric anesthesia using the Cicero Anesthesia Workstation]

A series of 52 infants underwent general or urological surgery; all were ventilated with the CICERO. Two different flows of fresh gas were used. In group I (n = 21) the fresh gas flow was set exactly at the level of the minute volume, representing a half-open, non-rebreathing system. In group II (n = 31) the fresh gas flow was adjusted to 10% of the required minute volume. Temperature and relative humidity of the inspired gas were measured continuously close to the tracheal tube. Anaesthesia was accomplished with 2 vol% isoflurane, 21-30 vol% oxygen in nitrous oxide. The results were compared with those achieved with our time-tested paediatric equipment, a SERVO 900D ventilator with a Fisher-Paykel humidifier (Group III, n = 35). Using a high fresh gas flow, no increase in relative humidity in the inspired gas could be detected. The values varied between 12% and 25% (group I). Reducing the flow of fresh gas as indicated above resulted in an increase in the relative humidity (group II). Over the evaluated period of 2 h, humidity increased slowly from an initial mean value of 20% to a maximum of something over 70%. Using the SERVO 900D ventilator combined with the Fisher-Paykel humidifier, humidity reached a value of greater 90% within 10 min after activation of the heated cascade. Humidity in the inspired gas should exceed 70% to avoid damage to infant airways. This will not be attained until after more than 2 h with unaided breathing systems, by when most operations performed on paediatric patients will already be over. Condensed water may aspirated by small infants. This potentially dangerous situation was only encountered in the CICERO circuit, and not in the system protected by the Fisher-Paykel cascade. Dry gases can result in thickened mucous and in obstruction of a small tracheal tube, which requires emergency reintubation. With artificial airways dry gases damage the ciliated epithelia of the trachea and cause loss of water and body heat. The temperature of the "cold" gases varied within a range of 21-33 degrees C and could not be adjusted by the anaesthetist. In the CICERO system, heating the gases at the valve only prevents mechanical failure caused by water condensation. In pediatric anaesthesia, variable heating and non-condensing humidity are essential. The dry and heated gases of the CICERO are not acceptable in the daily practice of paediatric anaesthesia.

[Measurement of end-expiratory carbon dioxide values in pediatric anesthesia]

This study dealt with two principles of the evaluation of end-expiratory CO2 in pediatric anaesthesia: detection of CO2-influenced infrared rays with a full stream analyzer attached to the tracheal tube; CO2 measurement with a side-stream analyzer connected to the breathing and ventilating system by a small tube. The linearity of the analyzers was tested with gas mixtures containing 3.0/5.0/7.0 vol% of CO2 cycling at an increasing rate. Additional mass-spectrometry has proven that the instruments are accurate within the clinical range of pediatric anesthesia. A maximal deviation of 8% develops when cycling rates increase to 40 per min. To detect quality differences in the analyzers, tangential constructions onto the CO2 curves plotted by the capnographs provided valuable quotients. Depending on the length of the tubing that feeds samples of respiratory gas into the side-stream analyzer, the CO2 curves were subject to sinus degradation with increasing respiratory rates. Capnography with full-stream analyzers depended on inspiratory zero CO2 content for reference purposes.

[Comparison of volume substitutes 5 percent human albumin and 6 percent hydroxyethyl starch (40,000/0.5) in pediatric anesthesia]

Human albumin 5% (HA), frequently used in paediatric anaesthesia as a human plasma substitute, could be replaced by hydroxyethyl starch 6% (HES) 40,000/0.5 provided its use would not entail any disadvantages but rather advantages instead. This problem was studied by examining 30 children (mean body weight 32.5 kg) in general anaesthesia. During about 3 hours of surgery the patients lost up to 15 per cent (approx. 400 ml) of blood volume. In a randomised study the blood loss was compensated either via HA or HES with 14 ml/kg body weight each, respectively. Blood pressure and pulse rate remained within the normal range. Haemodilution was represented by a drop in the erythrocyte count to about 3 million/microliter, haematocrit (HCT) to about 30% and haemoglobin to approx. 10 g/100 ml. Slight metabolic acidosis (Bodansky unit = -4 mmol/l) was found to be statistically not significant (= n.s.) with both methods, as was the difference in serum albumin and during serum electrophoresis. Serum [Na+] was reduced in those children who had been treated with HES, to 137.33 +/- 33.30 mmol/l; however, in those children who received HA with low sodium content (statistically significant difference = s.s.) the corresponding level was 134.15 +/- 2.36 mmol/l. Serum creatinine rose in each case from 60 to 80 mmol/l (s.s.), renal function being slightly impaired probably due to the anaesthesia and surgery. The value according to Quick's test and the partial thromboplastin time (PTT) remained in the normal range both with HA and HES treatment (in each case over 70% and below 25s, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

[Isoflurane in pediatric anesthesia]

Seventy patients 1-10 years of age were submitted to isoflurane (I) or halothane (H) anaesthesia (O2:N2O = 1:3); H was used as a reference substance. Under I anaesthesia, haemodynamic parameters proved to be well preserved. While the pulse rate under I increased significantly, the diastolic pressure decreased as a result of peripheral vascular dilatation. Baroceptor reflexes seemed to function more properly under the effect of I. Spontaneous respiration was definitely depressed by I. Respiratory rate, minute volume, end-expiratory CO2 and pCO2 values indicated CO2 accumulation. Younger children breathing spontaneously were subject to airway problems in I more than in H anaesthesia by decreasing negative occlusion pressures. Increasing doses of vecuronium bromide (5, 10, 15 and 70 micrograms/kg body wt.) accomplished muscular relaxation of various degrees, as tested by the train-of-four (TOF) method. The use of I in two age groups resulted in faster onset, more profound muscular relaxation, and longer duration in comparison with H; these results were statistically significant.

[Pseudarthrosis of the clavicle - an unnecessary complication? (author's transl)]

The pseudarthrosis of the clavicle is a rare complication of trauma surgery. The pseudarthrosis is mainly situated in the two medial quarters of the bone. The stable plate-osteosynthesis is regarded as the best treatment in combination with an autologous bone grafting in cases of atrophic or defect-pseudarthrosis. From 1970 to 1981 20 patients were treated at the BG Unfallklinik Tübingen, indication, operative procedures and the results are given. A bony union was achieved in all cases.

Extracellular K+ concentration and K+ balance of the gastrocnemius muscle of the dog during exercise

Exercise-induced changes of the extracellular and the venous K+ concentrations ([K+]e, [K+]ven) were measured continuously in autoperfused dog gastrocnemii using PVC liquid membrane electrodes. O2 consumption (VO2), blood flow and performance of the muscles were also determined. The muscles were stimulated indirectly and isotonic tetanic contractions (0.2 s) were produced every 0.7 s for more than 45 min. 1. [K+]e started to increase immediately after the onset of exercise and reached a maximal value of 7.4 meq/l after 4 min of exercise, thereafter it decreased, reaching 5.3 meq/1 at the end of the 12 min exercise. After 6 min of recovery [K+]e became lower than the control level. [K+]ven reached maximal values of 5.0 meq/l after 30 s of exercise and thereafter decreased slowly to 3.8 meq/l at the end of exercise. Thus, a K+ gradient of up to 3 meq/l was observed between the interstitial space and the venous blood. About 30 s after the end of exercise a net K+ uptake of up to 0.3 mu eq per min per g was observed. 2. The K+ loss of the muscle fibres reached maximal values of 1.5 mu eq per min per g at 1.5 min after the onset of exercise. Total K+ loss was 7% during 12 min of exercise and 12.5% of intracellular K+ during 45 min of exercise. 3. The changes of [K+]e correlated closely with performance and VO2 during exercise but not during recovery. On the other hand, blood flow correlated with the changes of [K+]e during both exercise and recovery. These results support the hypothesis that changes of [K+]e of the working muscle might be an important factor regulating exercise hyperemia.

[Indication, technique, and results for high tibial osteotomies (author's transl)]

In degenerative and posttraumatic osteoarthritis of the knee joint pain is a major indication for correctional osteotomy. In additon, the degree of arthrosis, axis deviation, range of motion and derangement of ligaments must be considered. In the cases reviewed supracondylar femur osteotomy, extraligamentar and high interligamentar osteotomy of the tibial head were utilized for correction. High tibial osteotomies were performed without using stabilizing plates. Autologous as well as homologous bone implants were added as needed. From the results presented we conclude, that the different methods of correctional osteotomies are equivalent, as long as the axis deviation, which is present in most cases, is corrected into a physiological valgus position. About 3/4 of the patient operated upon were improved as far as pain, range of motion and weigthbearing are concerned. Regression of the arthrotic structural changes could be demonstrated in a few cases only.

[Local contractility and acidosis in the ischemic myocardium of the dog (author's transl)]

In open chest dogs up to 8 side branches of the R, circumflexus and descendens were embraced and could selectively be occluded. With a new developed method local myocardial length changes in the ischemic areas, and with H+-sensitive minielectrodes the interstitial H+-activities were measured. All changes which were observed during the 3-30 min lasting coronary artery occlusions (H+-increases to about 500 neq/1, increases of diastolic length, decreases of the contraction amplitude, ST-elevations) returned to preocclusion levels during reperfusion. LVP and dp/dt remained unchanged during ischemia and reperfusion.