GaAs nanoscale membranes: prospects for seamless integration of III–Vs on silicon

The growth of compound semiconductors on silicon has been widely sought after for decades, but reliable methods for defect-free combination of these materials have remained elusive. Recently, interconnected GaAs nanoscale membranes have been used as templates for the scalable integration of nanowire networks on III-V substrates. Here, we demonstrate how GaAs nanoscale membranes can be seamlessly integrated on silicon by controlling the density of nuclei in the initial stages of growth. We also correlate the absence or presence of defects with the existence of a single or multiple nucleation regime for the single membranes. Certain defects exhibit well-differentiated spectroscopic features that we identify with cathodoluminescence and micro-photoluminescence techniques. Overall, this work presents a new approach for the seamless integration of compound semiconductors on silicon

3D Ordering at the Liquid–Solid Polar Interface of Nanowires

The nature of the liquid–solid interface determines the characteristics of a variety of physical phenomena, including catalysis, electrochemistry, lubrication, and crystal growth. Most of the established models for crystal growth are based on macroscopic thermodynamics, neglecting the atomistic nature of the liquid–solid interface. Here, experimental observations and molecular dynamics simulations are employed to identify the 3D nature of an atomic‐scale ordering of liquid Ga in contact with solid GaAs in a nanowire growth configuration. An interplay between the liquid ordering and the formation of a new bilayer is revealed, which, contrary to the established theories, suggests that the preference for a certain polarity and polytypism is influenced by the atomic structure of the interface. The conclusions of this work open new avenues for the understanding of crystal growth, as well as other processes and systems involving a liquid–solid interface

Patterns of language and auditory dysfunction in 6-year-old children with epilepsy

In a previous study we reported difficulty with expressive language and visuoperceptual ability in preschool children with epilepsy and otherwise normal development. The present study analysed speech and language dysfunction for each individual in relation to epilepsy variables, ear preference, and intelligence in these children and described their auditory function. Twenty 6-year-old children with epilepsy (14 females, 6 males; mean age 6:5 y, range 6 y–6 y 11 mo) and 30 reference children without epilepsy (18 females, 12 males; mean age 6:5 y, range 6 y–6 y 11 mo) were assessed for language and auditory ability. Low scores for the children with epilepsy were analysed with respect to speech-language domains, type of epilepsy, site of epileptiform activity, intelligence, and language laterality. Auditory attention, perception, discrimination, and ear preference were measured with a dichotic listening test, and group comparisons were performed. Children with left-sided partial epilepsy had extensive language dysfunction. Most children with partial epilepsy had phonological dysfunction. Language dysfunction was also found in children with generalized and unclassified epilepsies. The children with epilepsy performed significantly worse than the reference children in auditory attention, perception of vowels and discrimination of consonants for the right ear and had more left ear advantage for vowels, indicating undeveloped language laterality

Potential prophylactic use of benzodiazepines for hemodialysis-associated seizures

PubMed ID: 10805462Hemodialysis-associated seizure (HAS) is a common complication of hemodialysis. The efficiency of anticonvulsant drugs in treating or preventing seizures is poorly defined. In this study, children on long-term hemodialysis were examined for HAS and the effect of diazepam prophylaxis on HAS was investigated. Nine patients with a mean age of 14.1 ± 2.8 years had HAS and 4 with a mean age of 13.0 ± 4.4 years had never experienced HAS. The patients with HAS had tonic-clonic seizures. Four patients had focal slow-wave paroxysms, especially in the parieto-occipital regions; 2 had subcortical epileptiform discharges by electroencephalography. No correlation was observed between HAS and patient age, primary disease, prior history of seizures, type of dialysis, duration of hemodialysis, anemia, hyperparathyroidism, and administration of erythropoietin. Hypertension due to hypervolemia may also play a role in the development of HAS. Five patients with HAS first treated with phenobarbital (PB) had recurrence of seizures. As a dialyzable antiepileptic PB may be associated with an increased risk for HAS. In a preliminary study, we gave diazepam as a prophylactic therapy to 4 patients with HAS. During 6 months of follow-up, these patients had no seizures. The number of HAS was significantly different between the groups receiving PB and diazepam (z = -2.58, P=0.009). In conclusion, administration of diazepam per os to patients with HAS may be of value for preventing recurrence of HAS

The family attitudes towards febrile convulsions

PubMed ID: 10829846Giving adequate information about febrile convulsion and its prognosis would be helpful in alleviating parental stress, and would contribute to decrease in the morbidity of febrile convulsion. In this study, the knowledge level of parents on taking body temperature, and decreasing high fever, their attitudes during febrile convulsion and the impact of febrile convulsion on parents are evaluated. One hundred seventy-four parents of 132 children with FC were enrolled in the study. Twenty-seven per cent of parents had no thermometer at home, 32.8% of them did not know how to take a temperature, 72.2% of them did not know the minimum range of increased body temperature, and 69.5% of them did not know how to decrease the increased body temperature. Thirty-six percent of parents recognised the convulsions when their children suffered from them, the others assumed the convulsion were fainting spells (6.9%), near death state (38.5%) and suffocation (18.4%). Thirty-six per cent of parents brought their children to the hospital without doing anything themselves. Most parents (91.4%) had a fear of a recurrence of febrile convulsion in their children. Seventy-four per cent of parents complained of insomia, 24.3% parents had dyspeptic symptoms even 14 parents had weight loss due to dyspepsia. © 1995 Dr. K C Chaudhuri Foundation

Acute alternating hemiplegia: A Case Report

PubMed ID: 8993184Acute alternating hemiplegia in childhood is a rare disorder characterized by onset before 18 months of age and frequent attacks of alternating paralysis. In this case report, a 20-month-old boy having the diagnosis of acute alternating hemiplegia is presented. The diagnosis was based on clinical features. The frequency and severity of the hemiplegic attacks decreased following flunarizine therapy. In this case, cerebral perfusion was investigated during ictal and interictal periods. Tc-99m HMPAO-Brain single photon emission computed tomography (SPECT) revealed normal cerebral perfusion in ictal periods and hypoperfusion in interictal periods