Die Kinetik des thermischen Zerfalls von ClNO2 / Thermal Decomposition of ClNO2

ClNO2 decomposes incompletely at temperatures between 353 K and 373 K in the nonpolar inert solvent C7F15Cl according to

2 ClNO2=2 NO2+Cl2. (a)

Some ClNO is formed as by-product according to

2 ClNO2 = 2 ClNO+O2 . (b)

The reactions were followed photometrically by the arising NO2 . The time dependence of the brutto-reaction is described on the basis of the reaction scheme

ClNO2⇄NO2+Cl (1, - 1); NO3+NO2⇄NO+O2+NO2 (5, - 5);

ClNO2+ClNO2⇄Cl2+2NO2 (2, - 2); NO+ClNO2⇄ClNO+NO2 (6, - 6);

Cl+ClNO2⇄Cl2+NO2 (3, - 3); ClNO+ClNO2⇄NO±Cl2+NO2 (7, - 7);

NO2+ClNO2⇄NO3±ClNO (4, - 4); Cl+ClNO⇄Cl2+NO (8, - 8).

Arrhenius parameters for the steps (1) and (2) were obtained:

A1/s-1 = 1016.47±0.78, E1/kJ mol-1 = 152.3 ± 5.4;

A2/cm3 mol-1 s-1 = 1012.99±0.02 E2/kJ mol-1 = 88.7 ± 0.8.

The other parameters entering the rate equations were determined at 373 K as k-1/k3 = 1.5 ± 0.3; k4/cm3 mol-1 s-1 = 0.17; k7/cm3 mol-1 s-1 = 11.2. The enthalpies and entropies of the overall reactions (a), (b) and N2O4 = 2 NO2 (c) were measured directly (c) or indirectly:

(a) (b) (c)

⊿RH/kJ mol-1 46.4 83.7 65.3

⊿RS/J K -1 mol-1 61.8 85.7 97.8

(standard state 1 mol cm-3, T = 363 K).

Former investigations of the reaction in the gas phase and in solution which were interpreted exceptionally by step (1) followed by the fast step (3) are now interpreted on the basis of the new reaction scheme discussed here and are found to be consistent with it.

Zur Frage des Masseneffekts bei der lonenwanderung in Lösungen

Die Trennung der im Ionenradius fast übereinstimmenden seltenen Erden Y und Dy durch Gegenstrom-Ionenwanderung führt zur kathodenseitigen Anreicherung nicht des leichten Yttriums (At.-Gew. 88,9), sondern des schweren Dysprosiums (At.-Gew. 162,5). Ein gegenstromelektrolytischer Trennversuch, bei welchem ein verdünnt in Wasser gelöstes terbiumbromidhaltiges YBr3- DyBr3-Gemisch als Elektrolytflüssigkeit diente, ergab die als Beweglichkeitsverhältnisse interpretierbaren Einzeltrennfaktoren wY/wDy=0,9930 und wY/wTb = 0,9889.

Der Befund kann auf der Grundlage von LENARDS gaskinetischer Theorie der Ionenwanderung, deren Gültigkeit an dem für Isotopengemische vorliegenden experimentellen Material eingehend geprüft wird, qualitativ und quantitativ als gemischter Radien- und Masseneffekt verstanden werden.

Auf eine neue Möglichkeit der Bestimmung von Solvatationszahlen aus Isotopieeffekten der Ionenwanderung wird hingewiesen.

Bestimmung der Bildungsenthalpie von Nitroxychlorid (Chlornitrat, NO3Cl) als Beitrag zur Deutung der Kinetik des thermischen NO3Cl-Zerfalls in der Gasphase und in der Lösungsphase / Determination of the Enthalpy of Formation of nitroxy Chloride (Chlorine Nitrate, NO3Cl). A Contribution to the Interpretation of the Kinetics of the Thermal Decomposition of NO3Cl in the Gas Phase and in Solution

The dissociation energy values ⊿H0298(ClO- NO2) = 25.87 kcal mol-1 and ⊿H0 0(ClO-NO2),0 = 24.8 kcal mol-1 were derived from the standard enthalpy of formation of nitroxy chloride (NO3CI) ⊿Hf0 = 6.28 kcalmol-1 which has been determined from the reaction enthalpy of the gas phase reaction NOCI + NO3CI = 2 NO2 + Cl2. With the help of these data it was possible to show that in the thermal decomposition of NO3Cl, for which the overall reaction is NO3Cl = NO2 +½O2 + ½Cl2. at temperatures around 100 °C the equilibrium NO3Cl ⇄ NO2 + OCl is established. At the beginning of the reaction, there exists such a high OCl concentration that the decomposition occurs practically exclusively by the reactions

OCl + OCl + M ⇄Cl2O2 + M,

Cl2O2 + M → Cl2 + O2+M

and

OCl + OCl → Cl + OOCl,

the last of which is followed by Cl-consuming reaction steps, e.g. CI + NO3CI → NO3 + Cl2, apparently initiating chain reactions. The reaction step NO2 + NO3Cl → NO3 + NO2Cl, postulated from an investigation of the kinetics in a nono-polar inert solvent, and its daughter reactions probably occur for the gas phase reaction as well.

Multiple-aetiology enteric infections involving non-O157 Shiga toxin-producing Escherichia coli--FoodNet, 2001-2010

We describe multiple-aetiology infections involving non-O157 Shiga toxin-producing Escherichia coli (STEC) identified through laboratory-based surveillance in nine FoodNet sites from 2001 to 2010. A multiple-aetiology infection (MEI) was defined as isolation of non-O157 STEC and laboratory evidence of any of the other nine pathogens under surveillance or isolation of >1 non-O157 STEC serogroup from the same person within a 7-day period. We compared exposures of patients with MEI during 2001-2010 with those of patients with single-aetiology non-O157 STEC infections (SEI) during 2008-2009 and with those of the FoodNet population from a survey conducted during 2006-2007. In total, 1870 non-O157 STEC infections were reported; 68 (3.6%) were MEI; 60 included pathogens other than non-O157 STEC; and eight involved >1 serogroup of non-O157 STEC. Of the 68 MEI, 21 (31%) were part of six outbreaks. STEC O111 was isolated in 44% of all MEI. Of patients with MEI, 50% had contact with farm animals compared with 29% (P < 0.01) of persons with SEI; this difference was driven by infections involving STEC O111. More patients with non-outbreak-associated MEI reported drinking well water (62%) than respondents in a population survey (19%) (P < 0.01). Drinking well water and having contact with animals may be important exposures for MEI, especially those involving STEC O111.

Fracture near press-on interlocking enhances callus mineralisation in a sheep midshaft tibia osteotomy model

INTRODUCTION

Factors which impair fracture healing after intramedullary (IM) nailing of long bone fractures range from surgical and biological factors to mechanical parameters. Mechanical parameters known to prolong bony consolidation are share forces at the site of the fracture. Fracture near press-on interlocking reduces share forces directly at the fracture site and is hypothesised to enhance callus mineralisation. A sheep model of midshaft tibia osteotomies evaluates the technique.

MATERIALS AND METHODS

Fracture near interlocking was achieved by surfacing a custom made nail with special hutches that enable firm screw seating on top of the nail ("golf ball" structure). Virtual (fine element analysis (FEA)) and biomechanical pilot tests were completed before in vivo application in 12 adult female German black sheep. Midshaft tibia osteotomy was performed creating a subcritical 7 mm gap for delay in union. One group (n=6) was treated with reamed IM nailing employing the custom made nail and in addition to proximal and distal standard interlocking a fracture near press on interlocking was employed. A second group of six sheep without additional press on interlocking served as control. 10 weeks after operation the quality of fracture healing was determined by micro-CT.

RESULTS

The FEA showed that axial loading up to 4000N did not lead to implant fatigue. Fracture near press on interlocking led to significantly more callus mineralisation compared to the conventional interlocking procedure (0.567 g/cm(3) ± 0.106 g/cm(3) versus 0.434 g/cm(3) ± 0.0836 g/cm(3), p=0.043).

CONCLUSIONS

Fracture near press on interlocking increases callus mineralisation in a subcritical osteotomy model in sheep. The results indicate that the reduction of share forces at the fracture site after nailing procedures may be effective in reducing the time until bony consolidation.

Combined ipsilateral neck and axillary lymphadenectomy for metastatic skin cancers: a case series and surgical tips

In the absence of distant disease simultaneous skin cancer metastasis to neck and axillary lymph nodes necessitates both an axillary and neck en block lymphadenectomy. A combined ipsilateral neck and axillary lymph node dissection should involve an in-continuity dissection through the cervicoaxillary canal for optimal lymphatic and oncological clearance. Review of the literature reveals little published instruction on the procedure since the radical surgery performed by Bowden over 50 years ago. We present 4 cases where ipsilateral axillary and neck lymph node dissections were performed for metastatic melanoma and a case of apical axillary node dissection via a neck incision approach. Our surgical tips include performing apical axillary node dissection via the neck incision and consideration of clavicular osteotomy or clavicular excision. A transclavicular approach was taken in one patient who had an excellent functional outcome after a plate and screw fixation. One elderly patient required a middle third claviculectomy which reduced shoulder elevation but was not associated with functional impairment. We conclude the surgery is safe and associated with the usual morbidity ascribed with either an axillary or neck dissection undertaken in isolation. However, patients have a significant risk of disease relapse as would be expected due to the duel metastatic sites, multiple lymph node and neck involvement which are known to be independent poor prognostic factors on melanoma survival and relapse.

Synergism between hydrogen peroxide and seventeen acids against five agri-food-borne fungi and one yeast strain

AIMS

The objective of this study was to evaluate fungicidal efficacy of hydrogen peroxide administered in combination with 17 mineral and organic acids authorized for use in the food industry.

METHODS AND RESULTS

The assays were performed on a 96-well microplate using a microdilution technique based on the checkerboard titration method. The six selected strains (one yeast and five fungi) were reference strains and strains representative of contaminating fungi found in the food industry. Each synergistic hydrogen peroxide/acid combination found after fifteen minutes contact time at 20 °C in distilled water was then tested in conditions simulating four different use conditions. Twelve combinations were synergistic in distilled water, eleven of these remained synergistic with one or more of the four mineral and organic interfering substances selected. Hydrogen peroxide/formic acid combination remained effective against four strains and was never antagonistic against the other two fungi. Combinations with propionic acid and acetic acid stayed synergistic against two strains. Those with oxalic acid and lactic acid kept their synergism only against Candida albicans. No synergism was detected against Penicillium cyclopium.

CONCLUSIONS

Synergistic combinations of disinfectants were revealed, among them the promising hydrogen peroxide/formic acid combination.

SIGNIFICANCE AND IMPACT OF THE STUDY

A rapid screening method developed in our laboratory for bacteria was adapted to fungi and used to reveal the synergistic potential of disinfectants and/or sanitizers combinations.

Synergism between hydrogen peroxide and seventeen acids against six bacterial strains

AIMS

The objective of this study was to evaluate the bactericidal efficacy of hydrogen peroxide administered in combination with 17 mineral and organic acids authorized for use in the food industry.

METHODS AND RESULTS

The assays were performed on a 96-well microplate using a microdilution technique based on the checkerboard titration method. The six selected strains were reference strains and strains representative of contaminating bacteria in the food industry. Each synergistic hydrogen peroxide/acid combination found after 5-min contact time at 20°C in distilled water was then tested in conditions simulating four different use conditions. Thirty-two combinations were synergistic in distilled water; twenty-five of these remained synergistic with one or more of the four mineral and organic interfering substances selected. Hydrogen peroxide/formic acid combination was synergistic for all six bacterial strains in distilled water and remained synergistic with interfering substances. Six other combinations maintained their synergistic effect in the presence of an organic load but only for one or two bacterial strains.

CONCLUSIONS

Synergistic combinations of disinfectants were revealed, among them the promising hydrogen peroxide/formic acid combination.

SIGNIFICANCE AND IMPACT OF THE STUDY

A rapid screening method was proposed and used to reveal the synergistic potential of disinfectant and/or sanitizer combinations.

Kalanchoe pinnata inhibits mast cell activation and prevents allergic airway disease

Aqueous extract of Kalanchoe pinnata (Kp) have been found effective in models to reduce acute anaphylactic reactions. In the present study, we investigate the effect of Kp and the flavonoid quercetin (QE) and quercitrin (QI) on mast cell activation in vitro and in a model of allergic airway disease in vivo. Treatment with Kp and QE in vitro inhibited degranulation and cytokine production of bone marrow-derived mast cells following IgE/FcɛRI crosslinking, whereas treatment with QI had no effect. Similarly, in vivo treatment with Kp and QE decreased development of airway hyperresponsiveness, airway inflammation, goblet cell metaplasia and production of IL-5, IL-13 and TNF. In contrast, treatment with QI had no effect on these parameters. These findings demonstrate that treatment with Kp or QE is effective in treatment of allergic airway disease, providing new insights to the immunomodulatory functions of this plant.

Human herpesvirus 6 in biopsies from patients with gastrointestinal symptoms after allogeneic stem cell transplantation

Gastrointestinal complications are frequent after allogeneic stem cell transplantation (allo-SCT). Main differential diagnoses are graft-versus-host disease (GvHD) and viral infections. In this retrospective analysis, we included 50 patients with severe vomiting or diarrhea in the first year after allo-SCT. One hundred two biopsies obtained by colonoscopy or endoscopy of the upper gastrointestinal tract were analysed by conventional histology for signs of GvHD and by qualitative polymerase chain reaction (PCR) for viral DNA of human herpesvirus 6 (HHV-6) and other virus of the herpes family. DNA of HHV-6 was detected in 38 of 75 initial samples (51%) and in 19 of 27 follow-up biopsies (70%). In the initial samples (n = 75), HHV-6 DNA was detected in 20/37 (54%) biopsies in the presence of GvHD compared to 18/38 (47%) biopsies without signs of GvHD. At the time of the first endoscopic investigation, most patients received antiviral prophylaxis with aciclovir. None of the follow-up biopsies was HHV-6 DNA negative after antiviral treatment with aciclovir, foscarnet or ganciclovir. By univariate analysis, no risk factor for HHV-6 detection could be demonstrated. In this cohort of patients with severe gastrointestinal complications, there was no significant difference in the overall survival between patients with or without HHV-6 DNA detection in the gastrointestinal tract. In summary, the detection of HHV-6 DNA had no impact on overall survival. Moreover, antiviral therapy against HHV-6 was without effect. Thus, positive PCR results in GI tract samples do not necessarily reflect reactivation of HHV-6. Further studies are needed to define the significance of HHV-6 for GI tract symptoms after allo-SCT.

Novel model of placental tissue explants infected by cytomegalovirus reveals different permissiveness in early and term placentae and inhibition of indoleamine 2,3-dioxygenase activity

Human cytomegalovirus (HCMV) is the most common cause of viral intrauterine infection. Placental infection suggests hematogenous spread and permissiveness may vary according to the age of pregnancy. We set up and investigate permissivity of early and term placenta to HCMV with an ex vivo model of placental histocultures and evaluate the activity profile of IDO. Fourteen first trimester placentae were obtained following elective abortion and twelve term placentae after elective caesarean section. Fresh placental chorionic villi were isolated, washed and distributed on collagen sponge gels after overnight incubation with the virus. The culture medium was collected and fresh medium renewed regularly. Histology and immunohistochemistry showed preserved villous integrity in cultured placental histocultures. Infection could be seen in tissue sections of both early and term placentae, although early placentae were more permissive. Indoleamine 2,3-dioxygenase (IDO) is highly expressed in the placenta and is known to prevent maternal immune rejection. Constitutive IDO activity was higher in early, compared to term placentae and HCMV infection inhibited IDO activity in early placentae. IFN-γ-induced IDO activity was suppressed by HCMV in both early and term placentae. Our work shows a novel method of placenta organ culture. Our findings suggest that HCMV infects early placentae more strongly than term placentae. Early placental dysfunction through the inhibition of IDO activity may reveal a possible mechanism for miscarriages.

Differential liver proteome mapping of control and cadmium-fed rats

A comparative study of proteome maps from control and Cd-exposed rat liver was performed using a new technology of two-dimensional liquid chromatography separation method (PF-2D system, Beckman Coulter). Rats were fed for one month 0 or 100 μg Cd g(-1). The between-replicate and between-sample variations showed good repeatability and suitable reproducibility for the two dimensions of separation of proteins. In this complex mixture, PF-2D led to the separation of two major peaks which differed between control and Cd-exposed rat livers, one being identified by mass spectrometry as Cu/Zn superoxide dismutase (SOD), a well-known biomarker of Cd exposure, the other as phosphatidylethanolamine binding protein (PEBP). SOD content was decreased in Cd-exposed rat liver, compared to the control group which was corroborated by a significant decrease of SOD activity. PEBP content also tended to be decreased after Cd exposure. Present results demonstrate interest but also limitations of proteomic approach using PF-2D system to analyze effects of chemicals on organisms.

Environmentally Stable, Low Dielectric Polymers from Soluble Intermediates

We have investigated new polymers of poly(phenylene vinylene), PPV and poly(phenylene), PP. Like polyimides, these polymers can be spin-coated from soluble intermediates and converted to their thermally stable forms by elimination of small groups during a heating cycle. As such, these polymers are insulating. Both poly(phenylene vinylene) and poly(phenylene) also have the potential for metallic conductivity when properly doped. During curing, the complete removal of the leaving groups is important in determining the final behavior of the aromatized polymer film. Elimination of the leaving groups was followed by means of Rutherford Backscattering (RBS) and Forward Recoil Spectrometry (FRES) analysis for various curing conditions and environments. We will describe the curing and film-forming properties of these polymers, and discuss both their dielectric characteristics and thermal stability as a function of the curing conditions.

Continuous selective intraarterial infusion of nimodipine for therapy of refractory cerebral vasospasm

BACKGROUND

For endovascular treatment of vasospasm after aneurysmal subarachnoid hemorrhage (aSAH), an intraarterial treatment course with the calcium channel antagonist nimodipine infused for 30 min is proposed. As some patients still show ongoing vasospasm thereafter, we report on our experience with an extended time period of selective intraarterial nimodipine administration.

METHODS

In nine patients with aSAH and refractory cerebral vasospasm, we left the catheter in place within the internal carotid artery after angiography. On the neurosurgical ICU, a continuous infusion of intraarterial nimodipine was commenced, combined with intraarterial heparin anticoagulation. Therapy was controlled with extended neuromonitoring techniques.

RESULTS

Three patients died from refractory vasospasm and a fourth suffered lethal sepsis. Three patients survived in a good clinical condition, two of them without apparent neurologic deficit. The efficacy of intraarterial nimodipine was best verified with regional CBF monitoring. TCD failed to detect vasospasm in two patients and missed improvement in four. Brain tissue oxygenation increased in all patients, but was not indicative of vasospasm in one. CT perfusion reflected the treatment course adequately in the qualitative scans.

CONCLUSION

Selective continuous intraarterial nimodipine treatment for refractory cerebral vasospasm after aSAH seems feasible and may add to the endovascular therapeutic options. Appropriate monitoring technology is essential for further investigation of this novel technique.

Rapid phase-shifting fiber interferometer with optical stylus

Optical fiber interferometry holds many advantages for the online measurement of high-precision surfaces. Here, a fiber interferometer with a wavelength-scanning probe is reported. Such an interferometer requires active stabilization against the effects of temperature drift and vibration. A method of multiplexing dual wavelengths into the same fiber, combined with rapid phase shifting and real-time phase calculation, is investigated. Experimental data show the successful stabilization of the interferometer regardless of environmental perturbation.