The reduction behavior of sulfurized polyacrylonitrile (SPAN) in lithium-sulfur batteries using a carbonate electrolyte: a computational study.

Lithium-sulfur batteries (LSBs) have attracted attention due to their high theoretical energy density. This and various other advantages, such as the availability and non-toxicity of sulfur, raise interest in LSBs against the background of the energy revolution. However, a polysulfide shuttle mechanism can adversely affect the electrochemical performance of the cell. The sulfur redox properties are influenced, for example, by the electrolyte and the cathode material. Here, a computational study of the discharge process of an LSB with sulfurized poly(acrylonitrile) (SPAN) as the cathode material in combination with a carbonate electrolyte is presented. The nucleation of produced solid Li2S is compared to soluble Li2S. Dominating species are determined by comparing the Gibbs free energy of several species. We found that multiple lithiation steps occur before each Li2S detachment, preventing longer-chain polysulfide cleavage and a polysulfide shuttle. Through nucleating on the nitrogen-rich backbone of SPAN, Li2S units are stabilized by interactions with each other and with the nitrogen atoms. Experimental data show a potential drop and plateau during discharge, which is consistent with the calculated discharge profiles of SPAN with both soluble and nucleated Li2S, and hints at a direct solid-solid transition in the Li-SPAN cell during discharge when using carbonate-based electrolytes.

3D sub-nanometer analysis of glucose in an aqueous solution by cryo-atom probe tomography.

Atom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT's capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.

Field evaporation and atom probe tomography of pure water tips.

Measuring biological samples by atom probe tomography (APT) in their natural environment, i.e. aqueous solution, would take this analytical method, which is currently well established for metals, semi-conductive materials and non-metals, to a new level. It would give information about the 3D chemical structure of biological systems, which could enable unprecedented insights into biological systems and processes, such as virus protein interactions. For this future aim, we present as a first essential step the APT analysis of pure water (Milli-Q) which is the main component of biological systems. After Cryo-preparation, nanometric water tips are field evaporated with assistance by short laser pulses. The obtained data sets of several tens of millions of atoms reveal a complex evaporation behavior. Understanding the field evaporation process of water is fundamental for the measurement of more complex biological systems. For the identification of the individual signals in the mass spectrum, DFT calculations were performed to prove the stability of the detected molecules.

Gaussian Moments as Physically Inspired Molecular Descriptors for Accurate and Scalable Machine Learning Potentials.

Machine learning techniques allow a direct mapping of atomic positions and nuclear charges to the potential energy surface with almost ab initio accuracy and the computational efficiency of empirical potentials. In this work, we propose a machine learning method for constructing high-dimensional potential energy surfaces based on feed-forward neural networks. As input to the neural network, we propose an extendable invariant local molecular descriptor constructed from geometric moments. Their formulation via pairwise distance vectors and tensor contractions allows a very efficient implementation on graphical processing units (GPUs). The atomic species is encoded in the molecular descriptor, which allows the restriction to one neural network for the training of all atomic species in the data set. We demonstrate that the accuracy of the developed approach in representing both chemical and configurational spaces is comparable to the one of several established machine learning models. Due to its high accuracy and efficiency, the proposed machine-learned potentials can be used for any further tasks, for example, the optimization of molecular geometries, the calculation of rate constants, or molecular dynamics.

A cryogenic ice setup to simulate carbon atom reactions in interstellar ices.

The design, implementation, and performance of a customized carbon atom beam source for the purpose of investigating solid-state reaction routes in interstellar ices in molecular clouds are discussed. The source is integrated into an existing ultrahigh vacuum setup, SURFace REaction SImulation DEvice (SURFRESIDE2), which extends this double atom (H/D, O, and N) beamline apparatus with a third atom (C) beamline to a unique system that is fully suited to explore complex organic molecule solid-state formation under representative interstellar cloud conditions. The parameter space for this system is discussed, which includes the flux of the carbon atoms hitting the ice sample, their temperature, and the potential impact of temperature on ice reactions. Much effort has been put into constraining the beam size to within the limits of the sample size with the aim of reducing carbon pollution inside the setup. How the C-atom beam performs is quantitatively studied through the example experiment, C + 18O2, and supported by computationally derived activation barriers. The potential for this source to study the solid-state formation of interstellar complex organic molecules through C-atom reactions is discussed.

[Visualization of local cortical defects in Charcot foot using microcomputed tomography]. / Visualisierung lokaler kortikaler Defekte im Charcot-Fuß mittels Mikrocomputertomographie.

BACKGROUND: In the pathogenesis of diabetic neuropathic osteoarthropathy (Charcot's foot) fractures cause chronic destruction of soft tissue and bone structure. To improve an early diagnosis of Charcot foot, modern diagnostic imaging is mainly based on magnetic resonance imaging (MRI), for example in relation to the detection of cortical bone fractures. OBJECTIVES: In this study we investigated the cortical microstructure in cases of Charcot foot with respect to fractures and porosity in order to visualize local cortical defects. This may substantiate recent efforts in a reclassification based on MRI. MATERIAL AND METHODS: Using microcomputed tomography (microCT) we investigated bone parameters, such as cortical thickness and porosity in order to quantify the local metatarsal microstructure in cases of Charcot foot. RESULTS: All bone samples showed a high degree of cortical porosity including pores that perforated the cortical bone. The data suggest that areas with reduced cortical thickness coincide with large cortical pores that may serve as initial points for fractures. Whether the detected microfractures are physiological or artefacts of preparation could not be determined. CONCLUSION: By means of microCT we were able to visualize and quantify the extent of cortical porosity for the first time in high resolution. The data suggest that both cortical fractures and cortical porosity play an important role in the pathogenesis in cases of Charcot foot.

The MARS questionnaire: quality of life survey for acute rhinosinusitis.

PURPOSE: Acute rhinosinusitis (ARS) significantly reduces the quality of life (QoL). While intensive research has focused on the QoL in patients with chronic rhinosinusitis, data regarding the impact of ARS on the QoL are relatively sparse. The aim of this study was to construct and validate a simple, reliable QoL questionnaire for ARS patients, which is also one of the priorities set for EPOS 2012. METHODS: The questionnaire was constructed as follows: a review of literature, collection of symptoms as well as social and emotional consequences by a panel of ENT specialists and general practitioners, interviews with patients experiencing ARS, and a pre-test with another patient group. The questionnaire was validated by determining its internal reliability, discriminant validity, and responsiveness. The survey was given to 50 ARS patients at the time of diagnosis and again 14 days after treatment. The ARS diagnosis was established using the EPOS 12 criteria. The control group consisted of 50 medical students without any sinonasal symptoms. RESULTS: We developed a 13-item questionnaire, called the MARS (Measurement of Acute Rhinosinusitis). Cronbach's alpha was determined to be 0.679. The two-tailed t-test showed a statistically significant difference between the patient group and the control group (p = 0.0000). The SRM coefficient was 1.781. CONCLUSION: The MARS questionnaire is a QoL instrument developed and validated especially for patients with ARS. This survey demonstrated good internal consistency and excellent discriminant validity, responsiveness, and feasibility for use in daily clinical practice and research.

The effect of a flexible pylon system on functional mobility of transtibial amputees. A prospective randomized study.

BACKGROUND: Prosthetic component selection strongly influences the functional mobility of transtibial amputees. Until now, little attention has been paid to the connection between the prosthetic socket and the foot component. AIM AND DESIGN: Aim of this study was to compare a novel flexible with a conventional rigid pylon system in a prospective randomized trial in transtibial amputees to determine effects on gait and mobility. SETTING: The study was performed in a rehabilitation centre for geriatric amputees. POPULATION: Twenty-eight geriatric unilateral transtibial amputees (8 female, 20 male) with low degree of mobility were included. METHODS: At admission to the rehabilitation centre objective and subjective parameters were assessed including demographic data and levels of daily activity using standardized questionnaires. Three months after prosthetic fitting a follow-up was performed and additional parameters such as walking speed, step length and vertical ground reaction forces were examined using a dynamic gait analysis. RESULTS: The study revealed a significant improvement in step length (P=0.03), in using mobility aids (P=0.04) and benefits concerning the self-selected gait speed, the mobility and gait disorders using the flexible device. CONCLUSION: The results demonstrate advantages for the flexible system, resulting in a positive effect on the patient's gait accomplishments in a geriatric population. CLINICAL REHABILITATION IMPACT: The advantages of the dynamic pylon may improve clinical rehabilitation, especially for geriatric patients with vascular disorders, as it provides comfort and better prosthetic performance during gait as a short-term benefit and thus gives a better quality of life in the long-term.

Immediate revision in patients with bilateral recurrent laryngeal nerve palsy after thyroid and parathyroid surgery. How worthy is it?

The aim of the present study was to determine whether immediate revision surgery has benefits for patients with iatrogenic bilateral recurrent laryngeal nerve (RLN) palsy. From January 1, 2004 to January 30, 2011, 29 consecutive patients underwent immediate revision after total thyroidectomy. The cohort comprised 29 patients, 2 males and 27 females, aged 23 to 76 years (median 52 years). Identification of the type and extent of injury of each branch was reported in the protocol, and reconstruction was performed whenever possible. A complete transection of the nerve or one of its branches was found in 14 and 5 nerves, respectively. In three patients, the nerve was completely or partially transected on both sides. Seven anatomically intact nerves were injured by loaded ligature, in one case there was a sign of thermal damage and four nerves showed signs of excessive manipulation (thinning of the nerve trunk). Primary end-to-end anastomosis was performed in seven completely transected RLN and four transected anterior branches of RLN. None of the reconstructed nerve trunks or its branches regained function, although good muscle tone was observed. 23 of 38 intact nerves (61%) regained function, and normal vocalcord mobility on both sides was restored in only four patients. In all cases with regained vocal-cord mobility, functional recovery occurred within 3 months after primary surgery. In conclusion, immediate revision after thyroidectomy may help to indicate the type of RLN damage, which is a predictor of functional recovery and one of major factors influencing future therapeutic management.

[Penetrating laryngotracheal injury during a suicide attempt]. / Penetrierende laryngotracheale Verletzung beim Suizid.

The authors present a case of a 40-year-old man who intentionally stabbed himself several times in the trachea and larynx during a suicide attempt, and also inflicted other penetrating injuries of the stomach and liver upon himself. The preoperative examination using fiber-optic tracheoscopy and CT revealed only transection of the ligamentum cricothyroideum; the remaining two defects were discovered later, during the surgical revision. All three injuries were successfully treated with sutures, in one case using the transtracheal approach.

Production of aromatic green gasoline additives via catalytic pyrolysis of acidulated peanut oil soap stock.

Catalytic pyrolysis was used to generate gasoline-compatible fuel from peanut oil soap stock (PSS), a high free fatty acid feedstock, using a fixed-bed reactor at temperatures between 450 and 550°C with a zeolite catalyst (HZSM-5). PSS fed at 81 gh(-1) along with 100 mL min(-1) inert gas was passed across a 15 g catalyst bed (WHSV=5.4h(-1), gas phase residence time=34s). Results indicate that fuel properties of PSS including viscosity, heating value, and O:C ratio were improved significantly. For PSS processed at 500°C, viscosity was reduced from 59.6 to 0.9 mm(2)s(-1), heating value was increased from 35.8 to 39.3 MJL(-1), and the O:C ratio was reduced from 0.07 to 0.02. Aromatic gasoline components (e.g., BTEX), were formed in concentrations as high as 94% (v/v) in catalytically-cracked PSS with yields ranging from 22% to 35% (v/v of PSS feed).

Effect of operating conditions of thermochemical liquefaction on biocrude production from Spirulina platensis.

This study investigated the optimum thermochemical liquefaction (TCL) operating conditions for producing biocrude from Spirulina platensis. TCL experiments were performed at various temperatures (200-380°C), holding times (0-120 min), and solids concentrations (10-50%). TCL conversion at 350°C, 60 min holding time and 20% solids concentration produced the highest biocrude yield of 39.9% representing 98.3% carbon conversion efficiency. Light fraction biocrude (B(1)) appeared at 300°C or higher temperatures and represented 50-63% of the total biocrude. Biocrude obtained at 350-380°C had similar fuel properties to that of petroleum crude with energy density of 34.7-39.9 MJ kg(-1) compared to 42.9 MJ kg(-1) for petroleum crude. Biocrude from conversion at 300°C or above had 71-77% elemental carbon, and 0.6-11.6% elemental oxygen and viscosities in the range 40-68 cP. GC/MS of biocrude reported higher hydrocarbons (C(16)-C(17)), phenolics, carboxylic acids, esters, aldehydes, amines, and amides.

Occult thyroid carcinoma.

Some medical definitions remain the same for many years, others change due to the progress in the diagnostic tools, which are able to distinguish markers and symptoms until then undetectable. Occult thyroid carcinoma is a general term indicating clinically different situations, whereas the incidentally detected papillary thyroid microcarcinoma is the most important from the clinical point of view. It is fundamental, for therapeutic management, to determine biological parameters which would define a small group of papillary thyroid microcarcinomas with aggressive biological behaviour. The most promising genetic and molecular markers for papillary thyroid carcinoma risk stratification are discussed in this review. Preoperative evaluation of these markers, obtained through analysis of ultrasonography-guided fine needle biopsy specimens of papillary thyroid microcarcinoma, could be very valuable in guiding treatment of this type of cancer.

Implantable loop recorder in unexplained syncope: classification, mechanism, transient loss of consciousness and role of major depressive disorder in patients with and without structural heart disease.

OBJECTIVE: To stratify mechanisms and predictors of unexplained syncope documented by an implantable loop recorder (ILR) in patients with and without structural heart disease (SHD). DESIGN AND SETTING: Prospective study in consecutive patients of a university cardiac centre. PATIENTS AND METHODS: An ILR was implanted in 70 patients (34 male/36 female, aged 55 (17) years) in whom syncope remained unexplained after thorough testing. SHD was present in 33 patients (ischaemic cardiomyopathy in 16, dilated cardiomyopathy in 9 and hypertrophic cardiomyopathy in 8) and absent in 37 patients (mean (SD) left ventricular ejection fraction 46 (4)% vs 61 (7)%, respectively). RESULTS: A syncopal recurrence occurred during 16 (8) months in 30 patients (91%) with SHD and in 30 patients (81%) without SHD. Fifteen patients (45%) versus 19 patients (51%), respectively, had an ILR-documented arrhythmia at the time of recurrence which led to specific treatment. The remaining 15 patients (45%) with SHD and 11 patients (30%) without SHD had normal sinus rhythm at the time of the recurrence. On stepwise multivariate analysis only major depressive disorder was predictive for early recurrence during ILR follow-up (p = 0.01, hazard ratio = 3.35, 95% CI 1.1 to 7.1). Fifty seven per cent of patients with major depressive disorder had sinus rhythm during recurrence compared with 31% of patients without the disorder (p = 0.01). Conversely, no patient with major depressive disorder had asystole compared with 33% without (p<0.001). CONCLUSIONS: The presence of SHD has little predictive value for the occurrence or type of arrhythmia in patients with unexplained syncope. Patients with major depressive disorder are prone to early recurrence of symptoms and have no evidence of arrhythmia in most cases. The ILR leads to specific treatment in half of all patients.

An X-ray outburst from the rapidly accreting young star that illuminates McNeil's nebula.

Young, low-mass stars are luminous X-ray sources whose powerful X-ray flares may exert a profound influence over the process of planet formation. The origin of the X-ray emission is uncertain. Although many (or perhaps most) recently formed, low-mass stars emit X-rays as a consequence of solar-like coronal activity, it has also been suggested that X-ray emission may be a direct result of mass accretion onto the forming star. Here we report X-ray imaging spectroscopy observations which reveal a factor approximately 50 increase in the X-ray flux from a young star that is at present undergoing a spectacular optical/infrared outburst (this star illuminates McNeil's nebula). The outburst seems to be due to the sudden onset of a phase of rapid accretion. The coincidence of a surge in X-ray brightness with the optical/infrared eruption demonstrates that strongly enhanced high-energy emission from young stars can occur as a consequence of high accretion rates. We suggest that such accretion-enhanced X-ray emission from erupting young stars may be short-lived, because intense star-disk magnetospheric interactions are quenched rapidly by the subsequent flood of new material onto the star.

[Spindle cell and cuboidal renal cell carcinoma (loopoma). 10 case reports]. / Vretenobunecný a kuboidální renální karcinom (loopom). Popis 13 prípadu.

BACKGROUND: Current classification systems of neoplasms arising from renal parenchyma distinguish 5 categories of renal cell carcinoma (RCC), i.e. conventional RCC, papillary RCC, chromophobe RCC, collecting duct/medullary RCC and unclassified RCC. We present 13 cases of unusual and unclassified spindle and cuboidal renal cell carcinomas. METHODS AND RESULTS: The studied group consisted of 13 patients (7 men and 6 women). They ranged in age from 22 to 65 years (mean 57.3). Generally, the tumours were well circumscribed and confined to the kidney, whitish to grey on section with a diameter 4.5-13 cm (mean 8.6 cm). One patient was investigated for loin pain and nocturia. Three patients had staghorn nephrolithiasis and vague sonographic findings in renal parenchyma. In one patient the renal tumour was found when examined on follow-up examination for prostatic adenocarcinoma. None of our patients was known to have elevated levels of parathyroid hormone due to hyperplasia, adenoma or carcinoma of the parathyroid gland. Clinical follow-up of the patients ranged from 9 months to 8 years (mean 2.3 years). Microscopically, the tumours were composed of two main populations of cells: flattened, spindle cells with sparse cytoplasm and small cuboidal cells with clear to light eosinophilic cytoplasm. Eight patients are currently well without signs of recurrence or metastasis, one had metastasis in the regional lymph node at the time of nephrectomy, one died of unrelated cause, and three were lost to follow-up. CONCLUSIONS: We present 13 cases of unclassified RCC. Our cases were histologically, immunohistochemically and ultrastructurally similar to the hitherto reported case reports of this variant of RCC. It is obvious, that that variant of RCC should be recognised as a new subtype of RCC.

The contribution of MRI to the diagnosis of diffuse meningeal lesions.

We analysed MRI findings in patients in whom a diffuse abnormality of the meninges was revealed by MRI. We looked at T1 and T2-weighted spin-echo or fast spin-echo images and contrast-enhanced T1-weighted images. There were 15 patients with abnormalities on MRI, clinically suspected in ten. Four had meningoencephalitis, one meningeal and subcortical sarcoidosis nodules, four meningeal malignancies--one disseminated oligodendroglioma, one with meningeal infiltration around an adenocarcinoma, three meningeal infiltration by a haematological malignancy, and one a chronic subdural haematoma without a history of injury. We excluded patients with primary meningeal tumours and typical injury-related meningeal bleeding. The relatively small number of patients is due to both the infrequency of diffuse meningeal disease and to the low frequency of suspected meningeal pathology as an indication for MRI. The latter's diagnostic contribution is greatest in infectious disease and neoplastic infiltration, and less obvious in haematological malignancies. Contrast-enhanced T1-weighted images are most useful.

Unexplained syncope in patients with structural heart disease and no documented ventricular arrhythmias: value of electrophysiologically guided implantable cardioverter defibrillator therapy.

AIMS: To evaluate electrophysiologically guided implantable cardioverter defibrillator (ICD) therapy in patients with syncope, structural heart disease and no documented sustained ventricular tachycardia (sVT). METHODS AND RESULTS: Programmed ventricular stimulation (PVS) was performed in 52 patients (age 62+/-10 years): 40 patients had ischaemic and 12 patients had idiopathic dilated cardiomyopathy. On PVS sVT and ventricular fibrillation were induced in seven and four patients, respectively, and two patients spontaneously experienced symptomatic sVT. These patients received an ICD (ICD group, n=13). Non-inducible patients were left on conventional therapy (non-ICD group, n=39). During 5+/-2.8 years five ICD patients received therapies, all appropriate. There were seven non-sudden deaths and overall survival analysis revealed no significant difference. Recurrent syncope occurred in five ICD and four non-ICD patients and did not correlate well with sVT. The positive and negative predictive values of PVS for tachyarrhythmias or sudden death were 36 and 98%, respectively. CONCLUSION: Syncope per se does not necessarily herald a bad prognosis. PVS identifies high-risk patients. Induction of ventricular fibrillation with double or triple extrastimuli is of limited value. Patients with poor left ventricular function and bad clinical condition benefit most from an ICD. Syncope and sVT are not necessarily correlated during follow-up, which may merit consideration.

[Urologic complications in pelvic injuries]. / Urologické komplikace úrazu pánve.

OBJECTIVE: Urological complications of pelvic fractures include in particular rupture of the urinary bladder (RUB), injury of the posterior urethra (IPU) and erectile dysfunction (ED). The authors present their own group of patients and in particular the diagnostic and therapeutic algorithm in IPU. MATERIAL AND METHODS: In the Plzen Faculty Hospital in 1/1998 to 8/2002 a total of 19 patients were treated with serious urological complications of pelvic fractures--9x RUB, 11x IPU (once with RUB). RUB was in one instance intraperitoneal, in the remainder extraperitoneal. RESULTS: IPU was without dislocation 6x, with dislocation 5x. Primary "realignment" of the urethra was made in 6 patients (in dislocations and in concurrent rupture of the bladder). In the remaining 5 an epicystostomy was established. In 4 after an interval of 3 months a posterior resection urethroplasty was made because of a distraction defect. One patient with a distraction defect was referred to the urological department of the catchment area and in another patient after-treatment is planned. Severe ED developed in 6 IPU of 10, always in dislocations of the urethra. In one patient we lack information on erections. CONCLUSION: When IPU is suspected (urethrorhagia), dislocation of the prostate on examination p.r.) ascendent urethrography and IVU are essential. Do not catheterize before completed examination. Then needle epicystostomy is performed, in major dislocations of the urinary bladder or in associated injuries primary "realignment" of the urethra open on a catheter or endoscopically. In distraction defects after 12 weeks a posterior resection plastic operation follows.

Effect of redox potential on stationary-phase xylitol fermentations using Candida tropicalis.

Redox potential was used to develop a stationary-phase fermentation of Candida tropicalis that resulted in non-growth conditions with a limited decline in cell viability, a xylitol yield of 0.87 g g(-1) (95% of the theoretical value), and a high maximum specific production rate (0.67 g g(-1) h(-1)). A redox potential of -100 mV was found to be optimum for xylitol production over the range 0-150 mV [correction]. A shift from ethanol to xylitol production occurred when the redox potential was reduced from 50 mV to 100 mV as cumulative ethanol (Y(ethanol)) decreased from 0.34 g g(-1) to 0.025 g g(-1) and Y(xylitol) increased from 0.15 g g(-1) to 0.87 g g(-1) (alpha=0.05). Reducing the redox potential to 150 mV did not improve the fermentation. Instead, the xylitol yield and productivity decreased to 0.63 g g(-1) and 0.58 g g(-1) h(-1) respectively and cell viability declined. The viable, stationary-phase fermentation could be used to develop a continuous fermentation process, significantly increasing volumetric productivity and reducing downstream separation costs, potentially by the use of a membrane cell-recycle reactor.