Induced-Charge Capacitive Deionization: The Electrokinetic Response of a Porous Particle to an External Electric Field.

We demonstrate the phenomenon of induced-charge capacitive deionization that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electric field. The external electric field induces an electric dipole in the porous particle, leading to its capacitive charging by both cations and anions at opposite poles. This regime is characterized by a long charging time, which results in significant changes in salt concentration in the electrically neutral bulk, on the scale of the particle. We qualitatively demonstrate the effect of advection on the spatiotemporal concentration field, which, through diffusiophoresis, may introduce corrections to the electrophoretic mobility of such particles.

Unraveling the potential and pore-size dependent capacitance of slit-shaped graphitic carbon pores in aqueous electrolytes.

Understanding and leveraging physicochemical processes at the pore scale are believed to be essential to future performance improvements of supercapacitors and capacitive desalination (CD) cells. Here, we report on a combination of electrochemical experiments and fully atomistic simulations to study the effect of pore size and surface charge density on the capacitance of graphitic nanoporous carbon electrodes. Specifically, we used cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) to study the effect of potential and pore size on the capacitance of nanoporous carbon foams. Molecular dynamics simulations were performed to study the pore-size dependent accumulation of aqueous electrolytes in slit-shaped graphitic carbon pores of different widths (0.65 to 1.6 nm). Experimentally, we observe a pronounced increase of the capacitance of sub-nm pores as the applied potential window gets wider, from a few F g(-1) for narrow potential ranges (-0.3 to 0.3 V vs. Ag/AgCl) to ~40 F g(-1) for wider potential windows (-0.9 V to 0.9 V vs. Ag/AgCl). By contrast, the capacitance of wider pores does not depend significantly on the applied potential window. Molecular dynamics simulations confirm that the penetration of ions into pores becomes more difficult with decreasing pore width and increasing strength of the hydration shell. Consistent with our experimental results, we observe a pore- and ion-size dependent threshold-like charging behavior when the pore width becomes comparable to the size of the hydrated ion (0.65 nm pores for Na(+) and 0.79 nm pores for Cl(-) ions). The observed pore-size and potential dependent accumulation of ions in slit-shaped carbon pores can be explained by the hydration structure of the ions entering the charged pores. The results are discussed in view of their effect on energy-storage and desalination efficiency.

[Twenty-five years of experience in incisional hernia surgery. A comparative retrospective study of 432 incisional hernia repairs]. / 25 Jahre Erfahrung in der Narbenhernienchirurgie. Eine vergleichende, retrospektive Studie an 432 Narbenbruchoperationen.

INTRODUCTION: Incisional hernia surgery in Germany is changing from conventional techniques to mesh implantation. The relevance of different factors such as surgical technique, mesh material, and patient-related parameters concerning the outcome following mesh repair is still under debate. METHODS: In a comparative retrospective study of 432 incisional hernia operations on 348 patients we analyzed 11 autodermic hernioplasties, 241 Mayo procedures,and 180 mesh repairs over a 25-year time period. In addition to the quality of life following mesh implantation,the prognostic relevance of demographic, pre- and intraoperative parameters, surgical technique, mesh material, and the surgeon's experience were subjected to both univariate and multivariate analysis. RESULTS: With a mean follow-up of 9.7+/-8.8 years, the rate of major complications following mesh repair was 9% in contrast to 3% after the Mayo procedure (p=0.091). The sublay technique revealed less complications compared to the onlay procedure (p=0.016). The total recurrence rate following the overlapping Mayo repair was 37% in contrast to 15% after mesh implantation (p=0.001), with a significant superiority of the sublay technique over the inlay technique (p=0.043). The rate of recurrences and complications after autodermic hernioplasty was 72% and 36%,respectively. After mesh repair, 86% of the patients were better satisfied with the results after Marlex mesh compared to GoreTex (p=0.016). Mesh size was the only significant prognostic factor concerning quality of life following mesh implantation. The complication rate was determined significantly by the patients' risk factors, size of hernia, surgical technique, and the surgeon's experience, whereas the rate of recurrences was significantly influenced by the parameters obesity (BMI >25), size of hernia,and surgical experience. The recurrence rate decreased significantly with the surgeon's experience: a minimum of 16 mesh repairs led to a recurrence rate of less than 10%. CONCLUSIONS: Only the mesh repair revealed acceptable recurrence rates with high patient comfort. The sublay technique is superior to onlay concerning the complication rate, whereas the autodermic hernioplasty and inlay techniques are obsolete. The material of choice is polypropylene. The most important prognostic factor following mesh repair is the surgeon's experience.

Surgical cure for early rectal carcinoma and large adenoma: transanal endoscopic microsurgery (using ultrasound or electrosurgery) compared to conventional local and radical resection.

BACKGROUND AND AIMS: The minimally invasive technique of transanal endoscopic microsurgery (TEM) combines the benefits of local resections, a low complication rate and high patient comfort, with low recurrence rate and excellent survival rate after radical surgery (RS). The use of an ultrasonically activated scalpel rather than electrosurgery further improves the results of TEM. PATIENTS AND METHODS: A retrospective study was performed of 182 operations on 162 patients with early rectal carcinoma (pT1, G1/2) or adenoma to compare the outcome following four different kinds of surgical resection techniques: RS (anterior or abdominoperineal resection; n=27), conventional transanal resection using Park's retractor (TP; n=76), transanal endoscopic microsurgery (TEM) with electrosurgery (TEM-ES; n=45), and TEM with UltraCision (TEM-UC; n=34). One-third of the patients with RS (33%) received either a colostomy or a protective loop-ileostomy. RESULTS: Operation time with TEM-UC was significantly shorter than with TEM-ES or RS. Hospitalization was significantly longer with RS than for TEM or TP. Complication rate with TEM was significantly lower than with RS. Recurrence rate with RS and TEM was significantly lower than with TP, with a trend to TEM-UC being better than TEM-ES. Mortality rate was 3.7% with RS and 0 with TP and TEM. The 2-year survival rate was 96.3% with RS and 100% each with TP and TEM. CONCLUSION: TEM using UC seems to be the technique of choice. TP leads to an unacceptable recurrence rate, and RS results in a higher incidence of complication and impairment of life quality.

Transanal endoscopic microsurgery (TEM) for minimally invasive resection of rectal adenomas and "Low-risk" carcinomas (uT1, G1 - 2).

Transanal endoscopic microsurgery (TEM) presents a minimally invasive procedure for local removal of large rectal adenomas (>/= 2 cm) and early, so called "low-risk" carcinomas (uT1, G1 - 2) in curative as well as of advanced tumors in palliative intent. Over a 6-year period 92 TEM excisions of rectal tumors were carried out including 91 patients with 56 adenomas, 35 carcinomas (9 pTis, 17 pT1, 5 pT2, 3 pT3, 1 Ca after snare diathermy) and one neurinoma. Two patients of the carcinoma group had to be reoperated by means of anterior resection due to false preoperative rectal ultrasound examination (2 x uT1--> pT2). 4 patients required palliative therapy on account of age or high morbidity. After a mean follow-up time of 23 months (adenomas 23 months, pT1 carcinoma 26 months and advanced tumors 38 months) we encountered a total of 7 complications, of which in 5 cases surgical reintervention was necessary (5,4 %). One 86-year-old patient with a pT2-carcinoma, who was unsuitable for low anterior resection due to a high morbidity risk, died from myocardial infarction after emergency reintervention caused by postoperative bleeding. To date, overall 9 recurrences occurred (9,8 %). In the specific target group of TEM (adenomas and pT1, G1-2 carcinomas) consisting of n = 83 cases, the overall recurrence rate was 7,2 %, of which 5,3 % were due to adenomas and 11,5 % due to carcinomas. After palliative excision 2 recurrences occurred. These results of transanal endoscopic microsurgery (TEM) indicate that this technique has a useful place in curative, as well as in palliative management of rectal tumors.

The patterns of cell death and of macrophages in the developing forebrain of the tree shrew Tupaia belangeri.

The patterns of cell death and of macrophages were investigated in the forebrain and eyes of the tree shrew Tupaia belangeri during five phases of optic cup formation. Seventeen embryos were studied. Three- dimensional reconstructions were made from one embryo of each phase. In phase 1 (V-shaped optic evagination) a midline band of cell death passes through the closing anterior neuroporus. From phases 2 (optic vesicle) to 5 (far-advanced invagination) the midline band of cell death extends in the dorsal wall of the forebrain to its rostral pole and, further, into its ventral wall. At the approximate future position of the optic chiasm this ventral pycnotic area, predicted but so far unidentified by others, is connected to a previously described second band of cell death passing through the optic anlagen. Recently, evidence has been presented that chicken embryos develop holoprosencephaly and cyclopia when ventral forebrain structures are lost secondary to experimentally induced apoptosis. Our findings in Tupaia suggest that, in cases of spontaneous malformations of this kind, such an atypical pycnotic area in the ventral telencephalon might result from the defective regulation of cell death processes during optic cup formation. In the forebrain and eyes of Tupaia, the occurrence of bands of cell death precedes the appearance of the earliest intraepithelial macrophages. From phase 3 (onset of invagination) onwards almost all of them are concentrated along the band of cell death.

Inositol phosphate release and metabolism in rat left atria.

The phosphatidylinositol (PtdIns) turnover pathway in intact heart tissue differs from that in most cell types in that products of the inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] kinase pathway are not detected in 3H-labeling studies. In contrast, Ins(1,4,5)P3 kinase products are detected in isolated neonatal cardiomyocytes. To understand the basis for the observed properties of the cardiac pathway, a detailed study of inositol phosphate (InsP) release has been undertaken by using isolated adult rat left atria. Addition of norepinephrine to 3H-labeled atria caused a slow increase in 3H-labeled Ins(1,4,5)P3 and a more rapid increase in 3H-labeled Ins(1,4)P2, its immediate dephosphorylation product. The mass of Ins(1,4,5)P3 was high in unstimulated atria (13.5 +/- 1.1 pmol/mg tissue, mean +/- SEM, n = 4) and did not change with stimulation. Measurements of the specific activities of Ins(1,4,5)P3 and PtdIns(4,5)P2 provided an estimate of the turnover rate of Ins(1,4,5)P3 that was 20- to 40-fold lower than the rate of accumulation of 3H label in InsP1 and InsP2. In agreement with this, specific activities of InsP1 and InsP2 were higher than the specific activity of InsP3 in both control and stimulated atria. Neomycin (5 mmol/L) did not inhibit the accumulation of 3H-labeled InsP1 and InsP2 in left atria, even though it reduced the accumulation of 3H label in Ins(1,4,5)P3, providing evidence that InsP1 and InsP2 do not derive primarily from Ins(1,4,5)P3. Stimulation with norepinephrine for 20 minutes resulted in a parallel decrease in 3H-labeled Ins(1,4,5)P3 and in Ins(1,4,5)P3 mass, demonstrating that atria do not contain two different pools of Ins(1,4,5)P3.(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian blood pressure rhythms in elderly hypertensive patients.

Blood pressure was recorded for 24 h in 121 essential hypertensive patients aged between 20 and 90 years. To characterize the circadian blood pressure rhythm, the differences between the daytime blood pressures (recorded at 8-min intervals between 8 a.m. and 10 p.m.) and the night-time blood pressures (recorded at 30-min intervals between 10 p.m. and 8 a.m.) were calculated. The difference between daytime and night-time blood pressures was significantly (P less than 0.01) decreased in elderly hypertensive patients aged between 65 and 90 years compared with in those aged 20-39 years. In patients with heart insufficiency the circadian blood pressure rhythmicity was significantly (P less than 0.05) further reduced compared with in uncomplicated hypertensives. This may be explained by increased sympathetic tonus in patients with heart insufficiency and reduced vascular compliance may be the cause of the overall reduced circadian blood pressure rhythmicity in elderly hypertensive patients.

[Automatic detection of transient potentials in the EEG]. / Automatische Erkennung von Transienten im EEG.

A classifier based on the linear regression model was developed to automatically detect sharp transients in EEG, matching the definition of spikes and sharp waves accepted by IFSECN. Practical applications proved the accuracy of the method which succeeded in detecting 84% of sharp transients previously found by an experienced electronencephalographer. Computerized search for sharp transients in EEG records will be particularly useful in long term EEG records obtained from epileptic patients.