Order-disorder and ionic conductivity in calcium nitride-hydride.

Recently nitrogen-hydrogen compounds have successfully been applied as co-catalysts for mild conditions ammonia synthesis. Ca2NH was shown to act as a H2 sink during reaction, with H atoms from its lattice being incorporated into the NH3(g) product. Thus the ionic transport and diffusion properties of the N-H co-catalyst are fundamentally important to understanding and developing such syntheses. Here we show hydride ion conduction in these materials. Two distinct calcium nitride-hydride Ca2NH phases, prepared via different synthetic paths are found to show dramatically different properties. One phase (ß) shows fast hydride ionic conduction properties (0.08 S/cm at 600 °C), on a par with the best binary ionic hydrides and 10 times higher than CaH2, whilst the other (α) is 100 times less conductive. An in situ combined analysis techniques reveals that the effective ß-phase conducts ions via a vacancy-mediated phenomenon in which the charge carrier concentration is dependent on the ion concentration in the secondary site and by extension the vacancy concentration in the main site.

A comparative analysis of vertical and horizontal fixation disparity in sentence reading.

Humans have two, frontally placed eyes and during reading oculomotor and sensory processes are needed to combine the two inputs into a unified percept of the text. Generally, slight vergence errors, i.e., fixation disparities, occur but do not cause double vision since disparate retinal inputs fall into Panum's fusional area, that is, a range of disparity wherein sensory fusion of the two retinal images is achieved. In this study, we report benchmark data with respect to the mean magnitude and range of vertical compared to horizontal fixation disparities for natural reading. Our data clearly fit to an elliptical pattern of Panum's fusional area that corresponds with theoretical estimates. Furthermore, when we examined disparity-driven vergence adjustments during fixations by comparing monocular with binocular reading conditions, we found that only horizontal fixation disparities increased significantly under conditions of monocular stimulation. Also, no significant vertical fine-tuning (vergence adjustment) was observed for vergence eye movements during reading fixations. Thus, horizontal and vertical fixation disparities and vergence adjustments during reading showed quite different characteristics, and this dissociation is directly related to the functional role of vergence adjustments: vertical fusion - and vertical vergence - subserve the maintenance of a single percept and stereopsis by keeping the eyes in register and allowing for horizontal fusional processes to successfully operate over a vertically aligned input. A reliable and stable vertical alignment is, thus, a pre-requisite over which horizontal fusional responses (and depth perception) can work most efficiently - even in a task like reading.

Vergence responses to vertical binocular disparity during lexical identification.

Humans typically make use of both eyes during reading, which necessitates precise binocular coordination in order to achieve a unified perceptual representation of written text. A number of studies have explored the magnitude and effects of naturally occurring and induced horizontal fixation disparity during reading and non-reading tasks. However, the literature concerning the processing of disparities in different dimensions, particularly in the context of reading, is considerably limited. We therefore investigated vertical vergence in response to stereoscopically presented linguistic stimuli with varying levels of vertical offset. A lexical decision task was used to explore the ability of participants to fuse binocular image disparity in the vertical direction during word identification. Additionally, a lexical frequency manipulation explored the potential interplay between visual fusion processes and linguistic processes. Results indicated that no significant motor fusional responses were made in the vertical dimension (all p-values>.11), though that did not hinder successful lexical identification. In contrast, horizontal vergence movements were consistently observed on all fixations in the absence of a horizontal disparity manipulation. These findings add to the growing understanding of binocularity and its role in written language processing, and fit neatly with previous literature regarding binocular coordination in non-reading tasks.

Outcomes following prosthetic patch repair in newborns with congenital diaphragmatic hernia.

BACKGROUND: The anatomical defect in congenital diaphragmatic hernia (CDH) can usually be closed primarily but prosthetic patch repair may be required in newborns with a deficient diaphragm. High rates of patch failure and hernia recurrence (up to 50 per cent) have been reported. This study evaluated contemporary outcomes following patch repair of CDH at a UK paediatric surgical centre. METHODS: Medical records of newborns undergoing surgery for CDH between 1 February 1990 and 1 November 2010, and attending a multidisciplinary follow-up clinic, were examined. Operative details and patch utilization are reported. RESULTS: Of 118 newborns with CDH, 37 required a patch to the diaphragmatic defect. Gore-Tex® patches were used in 35 and biological Surgisis® patches in two. Eight babies additionally required an abdominal wall patch. Seven infants had an abdominal patch alone with primary diaphragm repair. A total of 102 infants (86·4 per cent) survived after surgery. Two early recurrences were both related to the use of biological patches, leading to revisional surgery with Gore-Tex® patch reconstruction. Diaphragmatic patch use was associated with a greater requirement for intensive cardiovascular and respiratory support, although there was no significant difference in mortality between patch versus primary diaphragm repair. The mortality rate was significantly higher among infants requiring abdominal wall patching (with or without a diaphragmatic patch): 40 per cent (6 of 15) versus 9·7 per cent (10 of 103) (P = 0·006). Postoperative survival rates for infants with a diaphragmatic patch alone, abdominal wall patch alone, and both abdominal and diaphragmatic patches were 86 per cent (25 of 29), 57 per cent (4 of 7) and 63 per cent (5 of 8) respectively. CONCLUSION: Prosthetic diaphragmatic hernia repair at this centre has a good outcome and low rate of recurrence (5 per cent). The recognition of an inadequate abdominal domain prenatally may additionally prove to be a useful marker for predicting increased mortality in newborns with CDH.

The structure, thermal properties and phase transformations of the cubic polymorph of magnesium tetrahydroborate.

The structure of the cubic polymorph of magnesium tetrahydroborate (γ-Mg(BH(4))(2)) has been determined in space group Ia3d from a structural database of the isoelectronic compound SiO(2); this has been corroborated by DFT calculations. The structure is found to concur with that recently determined by Filinchuk et al. (Y. Filinchuk, B. Richter, T. R. Jensen, V. Dmitriev, D. Chernyshov and H. Hagemann, Angew. Chem. Int. Ed., 2011, DOI: 10.1002/anie.201100675). The phase transformations and subsequent decomposition of γ-Mg(BH(4))(2) on heating have been ascertained from variable-temperature synchrotron X-ray diffraction data combined with thermogravimetric and mass spectrometry measurements. At ~160 °C, conversion to a disordered variant of the ß-Mg(BH(4))(2) phase (denoted as ß') is observed along with a further unidentified polymorph. There is evidence of amorphous phases during decomposition but there is no direct crystallographic indication of the existence of Mg(B(12)H(12)) or other intermediate Mg-B-H compounds. MgH(2) and finally Mg are observed in the X-ray diffraction data after decomposition.

A multidisciplinary combinatorial approach for tuning promising hydrogen storage materials towards automotive applications.

HyStorM is a multidisciplinary hydrogen-storage project aiming to synthesise and tune materials hydrogen storage properties for automotive applications. Firstly, unique high-throughput combinatorial thin-film technologies are used to screen materials' hydrogen storage properties. Then promising thin-film candidate compositions are synthesised and examined in the bulk. In this paper, we report on our results within the ternary compositions Mg-Ti-B and Ca-Ti-B. Primary screening of the Mg-Ti-B ternary identified a high capacity hotspot corresponding to Mg0.36Ti0.06B0.58, with 10.6 wt% H2 capacity. Partial reversibility has been observed for this material in the thin-film. Bulk Ti-doped Mg(BH4)2 composites show rehydrogenation to MgH2 under the conditions used. The synthesised thin-film Ca-Ti-B ternary showed only low hydrogen storage capacities. In the bulk, Ti-doping experiments on Ca(BH4)2 demonstrated reversible storage capacities up to 5.9 wt% H2. Further characterisation experiments are required to decipher the role of the Ti-dopant in these systems in both films and in the bulk.

Simple operative management of ingrown toenail using bipolar diathermy.

Ingrowing toenails (IGTN) cause significant discomfort for children and adults alike. Where conservative treatment fails, a surgical approach is usually adopted. Many surgical procedures have been described with varying complexity and outcome. We report a novel, simple technique which involves wedge excision of the ingrowing nail, and bipolar diathermy of the nail bed. Three-hundred and fifty-three procedures were carried out on 302 patients during the study period. Our re-operation rate for recurrence is 9.9%, which compares favourably with other techniques, and which lends itself to utilisation for minor surgery lists in primary care.

Less is best? The impact of urokinase as the first line management of empyema thoracis.

To assess the impact of intrapleural urokinase and small tube thoracostomy on the management of childhood empyema thoracis. The study population included 38 children presenting consecutively to a regional surgical unit with empyema thoracis from January 2001 to December 2003. Children with malignancy, immunodeficiency and complex intercurrent illness were excluded. Primary outcome variables were the need for second intervention and duration of stay, with other variables including duration of antibiotics, serial CRP and amelioration of pyrexia. Interventions were: tube thoracostomy (16-20 Fr) alone (n=2), tube thoracostomy (6-10 Fr)+urokinase (n=17), thoracoscopy (tube: 20-24 Fr) (n=9), thoracotomy (tube: 16-24 Fr) (n=10). There were no differences in age, weight or length of prodromal symptoms, between treatment groups. There were no differences in primary outcome variables, although no child undergoing thoracotomy required further intervention. The duration of intravenous antibiotics was similar in all groups. Amelioration of pyrexia was more rapid in children undergoing thoracotomy. There were no differences seen with regard to decline in CRP level. Small tube thoracostomy and intrapleural urokinase had a similar outcome to more invasive therapies such as thoracotomy or thoracoscopy thereby supporting the evidence base for urokinase and tube drainage as first line intervention.

Oesophageal atresia and tracheo-oesophageal fistula.

Oesophageal atresia-tracheo-oesophageal fistula has featured in paediatric surgery since its beginnings. The first successful primary repair was in 1941. With overall survival now exceeding 90% in dedicated centres, the emphasis has changed to reducing morbidity and achieving improvements in the quality of life. An overview of current and emerging strategies in managing patients with this condition is presented. Advances in developmental biology and molecular genetics reflecting improved understanding of the pathogenesis are highlighted.

Basic materials physics of transparent conducting oxides.

Materials displaying the remarkable combination of high electrical conductivity and optical transparency already from the basis of many important technological applications, including flat panel displays, solar energy capture and other opto-electronic devices. Here we present the basic materials physics of these important materials centred on the nature of the doping process to generate n-type conductivity in transparent conducting oxides, the associated transition to the metallic (conducting) state and the detailed properties of the degenerate itinerant electron gas. The aim is to fully understand the origins of the basic performance limits of known materials and to set the scene for new or improved materials which will breach those limits for new-generation transparent conducting materials, either oxides, or beyond oxides.

Double blind randomised controlled trial of topical glyceryl trinitrate in anal fissure.

AIMS: To determine the effectiveness and safety of topical glyceryl trinitrate (GTN) in the management of acute anal fissure in children. METHODS: Individual children were randomised to receive GTN paste or placebo for six weeks in addition to oral senna and lactulose. Patients took laxatives alone for a further 10 weeks. Each week a research nurse telephoned families to assess pain scores and give advice. Main outcome measures were validated standardised pain scores and time to painless defaecation. RESULTS: Forty subjects were recruited from 46 eligible children; 31 children completed the trial (13 in the GTN group and 18 in the placebo group). No differences in the proportion of those achieving pain free defaecation with relation to time were seen between the two groups. Similarly, there were no significant differences in pain scores between the two groups over the 16 week study period. However, in both groups pain scores had decreased significantly. There were no differences in the incidence of rectal bleeding, faecal soiling, presence of visible fissure, skin tag, or faecal loading at outpatient review at the time of recruitment, or at 6 weeks and 16 weeks. No serious adverse effects were observed. CONCLUSIONS: This study suggests that 0.2% GTN paste is ineffective in the treatment of acute anal fissures in childhood. However the overall fissure healing rate is high (84%) with associated reduction in pain scores, suggesting that a nurse based treatment programme can achieve a high rate of fissure healing.

Phenotypic presentation and outcome of esophageal atresia in the era of the Spitz classification.

PURPOSE: The aim of this study was to investigate contemporary patterns of presentation and outcome in newborns with esophageal atresia with or without tracheoesophageal fistula (OA) using modern prognostic criteria to appraise survival. METHODS: Over a 12-year period (1986 through 1997), 134 patients with OA were admitted to a single institution. Patient demographics, the presence of cardiac defects, other associated abnormalities (VACTERL), surgical intervention, and patient outcome were recorded. To identify and evaluate changes in the pattern of clinical presentation, frequency of associated anomalies and outcome, patients were analyzed during 4 consecutive time periods, 1986 to 1988, 1989 to 1991, 1992 to 1994, and 1995 to 1997. RESULTS: A primary repair or delayed primary repair was performed in 113 (84%) patients, with a staged procedure in 19 (14%). Two babies with trisomy 18 did not undergo surgery. Thirty-eight newborns (28%) had a major cardiac malformation (excluding patent ductus arteriosus, unless needing ligation), and 25 (19%) had recognized VACTERL associations. There was a significant increase in the proportion of infants with major cardiac defects diagnosed over the study period, 5 of 34 patients between 1986 and 1988 to 19 of 41 patients between 1995 and 1997 (chi(2) test, P <.001), but the incidence of VACTERL associations remained unchanged. Overall survival rate was 86% in those who underwent surgery. The relative risk of mortality in patients with major cardiac disease and VACTERL associations was 3.47 (95% CI; 1.51 to 7.96) and 2.54 (95% CI; 1.14 to 4.86), respectively. Birth weight was significantly higher in infants who survived (2.68 kg) compared with those who died (2.16 kg, P =.003). Thirty percent of infants with more than one system abnormality died compared with 8% of infants with 1, system abnormality (P =.004). CONCLUSIONS: This study has found a significant increase in the frequency of cardiac abnormalities encountered in a cohort of OA patients during the period under review. Cardiac disease and multiple abnormalities carried a substantial increased risk of mortality. In the era of the Spitz classification, the phenotypic presentation is important to accurately assess caseload severity and prognosis.

Umbilical pyloromyotomy--an alternative to laparoscopy?

AIMS: To evaluate the utility of umbilical pyloromyotomy for infantile hypertrophic pyloric stenosis (IHPS) compared to published series promoting laparoscopy. METHODS: Eighty-six babies with IHPS had pyloromyotomy using an umbilical skin fold incision. Operating times, post-operative hospital stay and cosmetic appearance of the umbilical wound were studied. Data extracted from recent series promoting laparoscopy were identified using a MEDLINE search strategy and used for comparative analysis. RESULTS: Mean operating time for umbilical pyloromyotomy was 30 min (range 15-50 min). All patients went home at an average period of 58 h (range 48-72 h) following surgery. The umbilical scar was barely visible in the post-operative period. Laparoscopic pyloromyotomy operating times ranging from 18-41 min (mean overall 30 min) are recorded in the literature. Post-operative stay following laparoscopy has been variable (23-91 h), where reported. In contrast with umbilical pyloromyotomy, "pox" marks observed following port insertions for laparoscopy can give an unsightly scar. CONCLUSIONS: This study has found that umbilical pyloromyotomy can be performed with minimal morbidity and equivalent operating times to laparoscopy. The shorter hospital stay reported in some series promoting laparoscopy must be balanced against local practice influencing hospital stay, the financial implications of offering a laparoscopic service, the skills needed for laparoscopy, and the short learning curve required by paediatric surgical trainees to become proficient at umbilical pyloromyotomy. The cosmesis of the umbilical incision is excellent. These findings suggest that umbilical pyloromyotomy is a reliable alternative to laparoscopy.

Ovarian adenocarcinoma in premenarchal girls.

Ovarian neoplasms are unusual in the paediatric age group; the majority of them are of germ cell origin. Malignant epithelial tumours of the ovary occur infrequently in adolescent girls. Ovarian carcinoma in particular is extremely rare before puberty. The authors describe 3 cases of adenocarcinoma of the ovary in premenarchal girls and highlight the unique characteristics of this tumour in this age group.

Posttraumatic high-flow priapism: treatment with selective embolisation.

Priapism is an uncommon problem in childhood. Most of the reported cases are in boys with sickle-cell disease or leukaemia. It occurs as a result of venous outflow obstruction, resulting in engorgement of the corpora cavernosa, and is termed "low-flow" priapism. In a small group of children priapism is due to uncontrolled arterial inflow, usually as a result of direct trauma. The authors report a case of posttraumatic arterial priapism in a child, successfully treated with selective embolisation of the internal pudendal artery. Recognition of this distinct entity is important, as it carries a good prognosis when appropriately treated.

Transanal endorectal coloanal surgery for Hirschsprung's disease: experience in two centers.

BACKGROUND/PURPOSE: Transanal mucosal proctectomy with low coloanal anastomosis has been used widely in the treatment of rectal malignancies, ulcerative colitis, and familial polyposis. The use of this technique for Hirschsprung's disease is a relatively new concept. The aim of this study was to evaluate and compare the results of transanal endorectal coloanal anastomosis (TECA) for Hirschsprung's disease from 2 centers. METHODS: All children who underwent TECA for Hirschsprung's disease at Alder Hey Children's Hospital, Liverpool, England from January 1995 to December 1998 (n = 41) and the Children's Hospital, Helsinki, Finland from June 1988 to December 1998 (n = 95) were evaluated. Patient demographics, age at diagnosis, initial management, length of aganglionic segment, and age at operation were documented. Postoperative complications and functional outcome were analyzed. RESULTS: Patient demographics were similar in the 2 centers. Age at diagnosis was less than 1 month in 71% of children at Liverpool, compared with 53% at Helsinki. Sixteen (39%) patients in Liverpool and 75 (79%) patients in Helsinki underwent primary TECA without colostomy. Postoperative enterocolitis occurred in 14 of 136 patients (10%). An ischemic stricture of the colon was documented in 4 children in the Liverpool series, 2 of whom had TECA as a salvage procedure after a previously failed Duhamel pull-through operation. Frequency of bowel movements, seen in the immediate postoperative period in most patients gradually improved with time from a median of 5 (range, 2 to 12) bowel movements a day at 3 months after TECA to 2 (range, 1 to 6) bowel movements a day at 2 years' follow-up. Assessment of continence was possible in 51 of 136 patients (37%) over the age of 4 years. Thirty-nine children had normal bowel function giving an overall success rate of 76%. CONCLUSIONS: Transanal endorectal coloanal anastomosis is a good technique for treatment of Hirschsprung's disease with few operation-related complications. Based on the data emerging from these 2 centers the functional outcome is highly satisfactory and comparable with other established procedures.

Clinical impact of abnormal gut flora in infants receiving parenteral nutrition.

OBJECTIVE: Illness is associated with the carriage of abnormal flora (aerobic Gram-bacilli except E. coli) in the oropharynx and rectum. The aim of this study was to investigate whether carriage of abnormal flora is associated with increased risk of sepsis and septicemia in surgical newborn infants. METHODS: A 2-year prospective study was carried out on 94 consecutive newborn infants requiring parenteral nutrition (PN) for gastrointestinal abnormalities. Throat and rectal swabs were taken on day 1 of PN and twice weekly. Patients were divided into two groups: abnormal flora (AF; n = 41) and normal flora (NF; n = 53). Sepsis was defined as clinical features of generalized inflammation requiring blood culture. Septicemia was the combination of sepsis and positive blood culture. RESULTS: Among the infants carrying abnormal flora Pseudomonas and Enterobacter spp. predominated. Duration of PN (AF median 30 days; NF median 9 days), incidence of sepsis (AF 29%; NF 6%), and septicemia (AF 22%; NF 2%) were significantly greater in the group of infants with abnormal flora. Surveillance cultures allow the detection of a subset of infants on PN at high risk of sepsis and septicemia. The degree of gut dysfunction related to the severity of underlying disease determines the duration of PN and the development of abnormal flora. The association between abnormal carriage and increased risk of sepsis and septicemia may be because of the intestinal endotoxin pool known to cause liver impairment and consequent suppression of systemic immunity.

'Congenital' hydronephrosis: limitations of diagnosis by fetal ultrasonography.

OBJECTIVE: To determine whether children presenting clinically with pelvi-ureteric junction obstruction had fetal hydronephrosis. PATIENTS AND METHODS: Forty-three children, born during or after 1985, presented clinically with pelvi-ureteric junction obstruction. Records of the maternal pregnancies were reviewed with reference to the findings of any fetal ultrasonography. RESULTS: In 25 patients fetal ultrasonography was performed at or beyond 30 weeks' gestation (mean 33.2). None had significant fetal hydronephrosis. CONCLUSION: Hydronephrosis due to pelvi-ureteric obstruction is not necessarily congenital and patients presenting clinically may differ inherently from those detected fetally.