Non-polymeric asymmetric binary glass-formers. II. Secondary relaxation studied by dielectric, 2H NMR, and 31P NMR spectroscopy.

We investigate the secondary (ß-) relaxations of an asymmetric binary glass former consisting of a spirobichroman derivative (SBC; Tg = 356 K) as the high-Tg component and the low-Tg component tripropyl phosphate (TPP; Tg = 134 K). The main relaxations are studied in Paper I [B. Pötzschner et al., J. Chem. Phys. 146, 164503 (2017)]. A high Tg contrast of ΔTg = 222 K is put into effect in a non-polymeric system. Component-selective studies are carried out by combining results from dielectric spectroscopy (DS) for mass concentrations cTPP ≥ 60% and those from different methods of 2H and 31P NMR spectroscopy. In the case of NMR, the full concentration range (10% ≤ cTPP ≤ 100%) is covered. The neat components exhibit a ß-relaxation (ß1 (SBC) and ß2 (TPP)). The latter is rediscovered by DS in the mixtures for all concentrations with unchanged time constants. NMR spectroscopy identifies the ß-relaxations as being alike to those in neat glasses. A spatially highly restricted motion with angular displacement below ±10° encompassing all molecules is involved. In the low temperature range, where TPP shows the typical 31P NMR echo spectra of the ß2-process, very similar spectral features are observed for the (deuterated) SBC component by 2H NMR, in addition to its "own" ß1-process observed at high temperatures. Apparently, the small TPP molecules enslave the large SBC molecules to perform a common hindered reorientation. The temperature dependence of the spin-lattice relaxation time of both components is the same and reveals an angular displacement of the SBC molecules somewhat smaller than that of TPP, though the time constants τß2 are the same. Furthermore, T1(T) of TPP in the temperature region of the ß2-process is absolutely the same as in the mixture TPP/polystyrene investigated previously. It appears that the manifestations of the ß-process introduced by one component are essentially independent of the second component. Finally, at cTPP ≤ 20% one finds indications that the ß2-process starts to disintegrate. More and more TPP molecules get immobilized upon decreasing cTPP. We conclude that the ß-process is a cooperative process.

Non-polymeric asymmetric binary glass-formers. I. Main relaxations studied by dielectric, 2H NMR, and 31P NMR spectroscopy.

In Paper I of this series of two papers we study the main relaxations of a binary glass former made of the low-Tg component tripropyl phosphate (TPP, Tg = 134 K) and of a specially synthesized (deuterated) spirobichroman derivative (SBC, Tg = 356 K) as the non-polymeric high-Tg component for the full concentration range. A large Tg contrast of the neat components is put into effect. Dielectric spectroscopy and different techniques of 2H nuclear magnetic resonance (NMR) as well as of 31P NMR spectroscopy allow to selectively probe the dynamics of the components. For all concentrations, two well separated liquid-like processes are identified. The faster α2-process associated with the low-Tg component TPP shows pronounced dynamic heterogeneities reflected by quasi-logarithmic correlation functions at low TPP concentrations. The slower α1-process involves the reorientation of the high-Tg component SBC. Its correlation function is Kohlrausch-like as in neat glass formers. The corresponding time constants and consequently their glass transition temperatures Tg1 and Tg2 differ more the lower the TPP concentration is. Plasticizer and anti-plasticizer effect, respectively, is observed. At low temperatures a situation arises that the TPP molecules isotropically reorient in an arrested SBC matrix (Tg2 < T < Tg1). At T < Tg2 the liquid-like reorientation of TPP gets arrested too. We find indications that a fraction of the TPP molecule takes part in the slower α1-process of the high-Tg component. All the features known from polymer-plasticizer systems are rediscovered in this non-polymeric highly asymmetric binary mixture. In Paper II [B. Pötzschner et al., J. Chem. Phys. 146, 164504 (2017)] we study the secondary (ß-) relaxations of the mixtures.

Causes of death in critically ill multiple sclerosis patients.

BACKGROUND: Patients with multiple sclerosis (MS) experience higher mortality rates as compared to the general population. While the risk of intensive care unit (ICU) admission is also reported to be higher, little is known about causes of death CoD in critically ill MS patients. AIM: To study the causes of death (CoD) in the series of critically ill patients with MS verified by autopsy. METHODS: We reviewed hospital electronic charts of MS patients treated at the neurological ICU of a tertiary care hospital between 2000 and 2015. We compared clinical and pathological CoD for those who were autopsied. RESULTS: Overall, 10 patients were identified (seven female; median age at death 65 years, range 27-80), and six of them were autopsied. The median MS duration prior to ICU admission was 27.5 years (range 1-50), and the median EDSS score at the time of ICU admission was 9 (range 5-9.5). The median length of ICU stay was 3 days (range 2-213). All the individuals in our series had experienced respiratory insufficiency during their ICU stay. The autopsy examination of brain tissue did not reveal evidences of MS lesions in one patient. In another patient, Lewy bodies were found on brain immunohistochemistry. CONCLUSION: Mortality in critically ill MS patients is largely driven by respiratory complications. Sporadic disparities between clinical and pathological findings can be expected.

Compressibility and compactibility of granules produced by wet and dry granulation.

The bulk properties, compactibility and compressibility of granules produced by wet and dry granulation were compared applying a rotary tablet press, three different morphological forms of calcium carbonate and two particle sizes of sorbitol. Granules from both granulation methods possessed acceptable flow properties; however, the ground (Mikhart) and cubic (Scoralite) calcium carbonate demonstrated better die-filling abilities in the tablet press than the scalenhedral calcium carbonate (Sturcal). The wet processed granules showed in general larger compression properties. This was explained as these granules were mechanical stronger and had a higher initial porosity. In some cases, a large particle surface area of calcium carbonate and sorbitol resulted in a small, insignificant improvement of the consolidation characteristics. A correlation between the compression and compaction characteristics was demonstrated.

Granule fraction inhomogeneity of calcium carbonate/sorbitol in roller compacted granules.

The granule fraction inhomogeneity of roller compacted granules was examined on mixtures of three different morphologic forms of calcium carbonate and three particle sizes of sorbitol. The granule fraction inhomogeneity was determined by the distribution of the calcium carbonate in each of the 10 size fractions between 0 and 2000 microm and by calculating the demixing potential. Significant inhomogeneous occurrence of calcium carbonate in the size fractions was demonstrated, depending mostly on the particles sizes of sorbitol but also on the morphological forms of calcium carbonate. The heterogeneous distribution of calcium carbonate was related to the decrease in compactibility of roller compacted granules in comparison to the ungranulated materials. This phenomenon was explained by a mechanism where fracturing of the ribbon during granulation occurred at the weakest interparticulate bonds (the calcium carbonate: calcium carbonate bonds) and consequently exposed the weakest areas of bond formation on the surface of the granules. Accordingly, the non-uniform allocation of the interparticulate attractive forces in a tablet would cause a lowering of the compactibility. Furthermore, the ability of the powder to agglomerate in the roller compactor was demonstrated to be related to the ability of the powder to be compacted into a tablet, thus the most compactable calcium carbonate and the smallest sized sorbitol improved the homogeneity by decreasing the demixing potential.

Improving the compaction properties of roller compacted calcium carbonate.

The effects of roller compaction process parameters, morphological forms of calcium carbonate and particle size of sorbitol on flow, compaction and compression properties were investigated. The morphology of the calcium carbonate and the sorbitol particle size were more influential on the compaction properties than the settings of the roller compactor. The roller compaction process was demonstrated to be robust and stable in regard to flowability and compactibility. The flowability of the granules was improved adequately to facilitate compression in a production scale rotary tablet press. By adding sorbitol to the calcium carbonate, the compressibility - characterized by the Walker coefficient W(ID) - and the compactibility C(P) were improved considerably. A correlation between the consolidation characteristics was demonstrated. Compactibility data from the compaction simulator correlated with the tablet press for two of the calcium carbonates, the cubic form and the ground quality.

[Short-term dynamics of intertidal microphytobenthos biomass. Mathematical model]. / La dynamique à court terme de la biomasse du microphytobenthos intertidal. Formalisation mathématique.

We formulate a deterministic mathematical model to describe the dynamics of the microphytobenthos of intertidal mudflats. It is 'minimal' because it only takes into account the essential processes governing the functioning of the system: the autotrophic production, the active upward and downward migrations of epipelic microalgae, the saturation of the mud surface by a biofilm of diatoms and the global net loss rates of biomass. According to the photic environment of the benthic diatoms inhabiting intertidal mudflats, and to their migration rhythm, the model is composed of two sub-systems of ordinary differential equations; they describe the simultaneous evolution of the biomass 'S' concentrated in the mud surface biofilm--the photic layer--and of the biomass 'F' diluted in the topmost centimetre of the mud--the aphotic layer. Qualitatively, the model solutions agree fairly well with the in situ observed dynamics of the S + F biomass. The study of the mathematical properties of the model, under some simplifying assumptions, shows the convergence of solutions to a stable cyclic equilibrium, whatever the frequencies of the physical synchronizers of the production. The sensitivity analysis reveals the necessity of a better knowledge of the processes of biomass losses, which so far are uncertain, and may further vary in space and time.

[Primary delayed indication for single-step continence resection in 300 patients with acute colonic diverticulitis]. / Die primär verzögerte Indikation zur einzeitigen Kontinenzresektion bei 300 Patienten mit akuter Colondivertikulitis.

Since 1980, a total of 300 patients with colonic diverticulitis have undergone surgery. A vital indication forced us to do an emergency colostomy or Hartmann procedure in 22 cases. Except for 3 patients, the indication for resection was intentionally delayed by means of conservative treatment and a primary anastomosis was performed. Histological findings verified an inflammatory tumor, and abscess, a fistula or perforation in 50% and circumscript inflammation in 37%. The main complications were drainage problems (infection/retention of secretion, n = 18) and anastomosis insufficiency (n = 5), lethality was less than 2%. In general, we think that multistep surgery is not mandatory--even in advanced cases.

Laparoscopic appendectomy.

Appendectomy was performed using a laparoscopic approach in 915 patients. The collected data show that the technique is as feasible, rapid, and safe as open surgery. Few wound infections, minimal pain, and rapid postoperative mobilization are the main arguments in favor of laparoscopic appendectomy. The most important potential benefit, a lower incidence of long-term complications such as adhesive intestinal obstruction, remains to be confirmed by prolonged follow-up of our patients.

[Cryopreservation of human erythrocytes with hydroxyethyl starch (HES)--Part 2: Analysis of survival]. / Kryokonservierung von Human-erythrozyten mit Hydroxyethylstärke (HES)--Teil 2: Vitalitätsanalytik.

Red blood cells (RBC) were obtained from 5 whole blood units by centrifugation and were purified using a simple washing procedure. Hematocrit and HES concentration in the 108-ml samples to be frozen were adjusted to 40% (v/v) and 12% (w/w), respectively. Cooling was performed by submerging into liquid nitrogen using containers to generate a flat sample geometry (3 mm thickness). After thawing in a shaking water bath, HES and free hemoglobin were removed in a simple washing step. To investigate the influence of the resuspension medium, the RBC were transferred into freshly drawn autologous plasma and into Locke's solution. Survival after thawing in terms of saline stability reached 86.3 +/- 2.3%. The cryopreservation procedure caused no major changes with regard to osmotic fragility, 2,3-DPG or intracellular Na+ and K+. ATP was reduced by 16%, but this had completely recovered after 3 h resuspension in autologous plasma. Some morphological changes present after thawing (e.g. stomatocytes, echinocytes) also recovered after 1.5 h. In conclusion, those RBC which survived the preservation process can be considered to be fully viable with regard to the parameters investigated.

Laparoscopic appendectomy in 625 cases: from innovation to routine.

Invented in 1982 by Semm, a gynecologist, laparoscopic appendectomy began to be used in operative surgery in 1987. Since then, we have modified and performed this promising procedure in > 700 patients. The data of the first 625 cases indicate that laparoscopic appendectomy is safe and practicable. With regard to patient age as well as the acuteness of the inflammation, the patients represent a cross section of the normal appendicitis population. The major benefits and possible problems of the method are presented and discussed.

[Laser-assisted laparoscopic appendectomy]. / Die lasergestützte laparoskopische Appendektomie.

Our constantly good experience with approximately 300 laparoscopic appendectomies (almost 520 at present (Feb. 90)) encouraged us in 1988 to introduce Laser technology into laparoscopic abdominal surgery. 22 patients underwent Laser-aided laparoscopic appendectomy. We obtained good results by means of using both an CO2-Laser and a Nd-YAG-Laser.

Modified laparoscopic appendectomy in surgery. A report on 388 operations.

Laparoscopic appendectomy, introduced in gynecology by Semm in 1982, has been modified and practiced in our surgical ward since May 1987 in more than 450 patients suffering from all stages of acute and chronic vermix diseases. We report our data on the first series of 388 operations, in which we had the encouraging experience that laparoscopic appendectomy is a practicable and reasonable alternative to routine surgery.

[Laparoscopic appendectomy--alternative therapy in all stages of appendicitis?]. / Die laparoskopische Appendektomie--Alternativtherapie in allen Appendizitisstadien?

1989 we reported on our first series of 277 laparoscopic appendectomies. This technique was introduced by Semm in 1982. We acquired this procedure in 1987 and modified this operation-technique for surgical routine. We could demonstrate that laparoscopic appendectomy can be performed in chronic, acute and even in peracute cases. We introduce the facts of 500 laparoscopic appendectomies.