Electrochemical de-alloying in two dimensions: role of the local atomic environment.

We investigate by in situ scanning tunnelling microscopy (STM) the potential dependence of the electrochemical dealloying of NiPd monoatomic layers electrodeposited on Au(111). The dealloying process is achieved by Ni selective dissolution and was studied as a function of NiPd composition: for an alloy with a Ni content ≥70%, quasi-complete Ni dissolution is achieved at a potential of -0.9 VMSE whereas for a Ni content <70%, Ni dissolution at the same potential drastically slows down after the removal of small amounts of Ni. The alloy morphology at this "passivation state" is characterized by the presence of holes in the alloy monolayer with evidence for the Pd enrichment at the hole edges. These findings are confirmed by Monte Carlo simulations. Further Ni dissolution at passivation was achieved by applying more positive potentials which depend on the alloy composition. These results allowed us to determine the correlation between the Ni dissolution onset potential and the local Pd content.

Selective growth and dissolution of Ni on a PdAu bimetallic surface by in situ STM: determining the relative adsorbate-substrate interaction energy.

By studying the electrochemical growth and dissolution of a Ni monolayer on a PdAu bimetallic surface with in situ STM, we demonstrate that Ni grows preferentially on Au(111) in a wide potential range. In contrast, a Ni monolayer covering the entire bimetallic surface can be selectively dissolved from Pd islands. We show that the Ni-substrate interactions play a key role in this selectivity, and we estimate the binding energy of Ni to Pd to be 80 meV smaller than that of Ni to Au.

Single-step electrochemical nanolithography of metal thin films by localized etching with an AFM tip.

This work introduces electrochemical nanolithography (ENL), a single-step method in which a metal thin film is locally etched without application of a mask on a 100 nm length scale with an electrochemical atomic force microscope (AFM). The method requires the application of ultra-short voltage pulses on the tip (nanosecond range duration, 2-4 V amplitude), while both the sample and the metalized tip are under independent potentiostatic control for full control of interface reactions in an AFM electrochemical cell. It is demonstrated that Cu films as well as Co and Cu/Co sandwich magnetic films can be patterned if negative voltage pulses are applied to the tip. This method also applies to films deposited on an insulating substrate. Moreover the lateral dimension of lithographed structures is tunable, from a few micrometers down to 150 nm, by appropriate choice of ENL conditions. Simulation of the dissolution process is discussed.

Potential-induced strain relaxation in au mono- and bilayer films on Pt(111) electrode surfaces.

In situ scanning tunneling microscopy observations of 1-2 monolayer thick Au films on Pt(111) electrodes are presented, which show a complex, potential-dependent structural phase behavior of the Au film. Starting from a pseudomorphic structure at <0.35 V(Ag/AgCl), a sequence of transitions into dislocation network structures occurs with increasing potential: (1x1)--> "striped phase" --> "hex phase" in the Au bilayer, (1x1)--> striped phase in the Au monolayer. This is explained by a reduction of the in-plane stress in the Au surface layer(s) due to anion adsorption and a strain energy minimization as described by the Frenkel-Kontorova model.

The role of atomic ensembles in the reactivity of bimetallic electrocatalysts.

Bimetallic electrodes are used in a number of electrochemical processes, but the role of particular arrangements of surface metal atoms (ensembles) has not been studied directly. We have evaluated the electrochemical/catalytic properties of defined atomic ensembles in atomically flat PdAu(111) electrodes with variable surface stoichiometry that were prepared by controlled electrodeposition on Au(111). These properties are derived from infrared spectroscopic and voltammetric data obtained for electrode surfaces for which the concentration and distribution of the respective metal atoms are determined in situ by atomic resolution scanning tunneling microscopy with chemical contrast. Palladium monomers are identified as the smallest ensemble ("critical ensemble") for carbon monoxide adsorption and oxidation, whereas hydrogen adsorption requires at least palladium dimers.

Sarcoidosis presenting as an intramedullary spinal cord lesion.

OBJECTIVES: Sarcoidosis affects the spinal cord in only 0.43% of patients with sarcoidosis. Usually there is systemic involvement prior to the development of cord lesions. We present a case of sarcoid isolated to the intramedullary spinal cord, which was a diagnostic and therapeutic challenge. We review the case and then present a review of the literature with an emphasis on presentation, diagnosis and treatment. METHODS: We have reviewed a patient who presented with an isolated sarcoid granuloma affecting the cervical spinal cord. All pertinent history and physical information was extracted from the patient's chart and through patient interview. Laboratory, radiographic and pathological investigations are presented. RESULTS AND CONCLUSIONS: Fourteen patients have been reported with isolated intramedullary spinal cord sarcoidosis. Current practice supports the role of surgery for biopsy; mainstay of treatment is corticosteroids.

Effect of eye rubbing on signs and symptoms of allergic conjunctivitis in cat-sensitive individuals.

OBJECTIVE: To evaluate the effect of eye rubbing on signs and symptoms of allergic conjunctivitis in cat-sensitive individuals. DESIGN: Two prospective, nonrandomized comparative studies. PARTICIPANTS: Thirteen patients in the first study and 20 patients in the second study with a documented history of acute allergic conjunctivitis induced by exposure to cats were enrolled. INTERVENTION: In the first trial, all patients had one eye rubbed 15 times by the investigator without exposure to airborne allergens. Both eyes were evaluated after 5, 15, 30, and 60 minutes using subject questionnaires and slit-lamp examination. At least 1 week later, each patient was exposed to cat dander for 75 minutes; 15 minutes after entering the cat room, each patient had one eye rubbed 15 times by the examiner. Subjects' eyes were then evaluated using questionnaires and slit-lamp examination. In the second trial, the visits were identical to the first trial, except that the rubbed eye in each visit was rubbed 20 times and with more force, and that patients wore masks during exposure to cat dander. MAIN OUTCOME MEASURES: In both studies, the difference between patients' rubbed and nonrubbed eyes with respect to ocular itching, chemosis, and hyperemia was noted 5, 15, 30, and 60 minutes after controlled eye rubbing. RESULTS: Without exposure to the cat room, rubbed eyes exhibited increased itching at 5 minutes in both studies and at 15 minutes in the second study (P < 0.05), increased chemosis at 5 and 15 minutes in the second study (P < 0.05), and increased hyperemia at 5 minutes in the second study (P < 0.05) compared with nonrubbed eyes. During exposure to cat dander, rubbed eyes consistently exhibited increased itching at 5, 15, and 30 minutes in the first and second study as well as at 60 minutes in the second study compared with nonrubbed eyes. Furthermore, during exposure to cat dander, rubbed eyes consistently exhibited increased chemosis at 5 and 15 minutes (P < 0.05) and increased hyperemia at 5, 15, and 30 minutes (P < 0.05) in the second study compared with nonrubbed eyes. CONCLUSIONS: Firm eye rubbing causes a mild and transient increase in ocular itching, chemosis, and hyperemia. However, after exposure to cat allergens in cat-sensitive individuals, the effects of eye rubbing are longer and more dramatic. Eye rubbing may play a role in ocular signs and symptoms of allergic conjunctivitis in cat-sensitive individuals, especially after exposure to cat dander.

Surgical pitfalls, their consequences, transient complications.

The methodology of this paper is based entirely on the experiential backgrounds of the authors. It outlines those factors which have become recognized as potentially important issues to patients who are considering recommendations of surgical treatment for their intractable epilepsy. Thus, on the one hand, it includes the important generic aspects of Informed Consent, while on the other hand there must be a very comprehensive and, when the operation is to be carried out under local anesthesia, a very detailed explanation of the preparation and the sequential steps in the surgical procedure. This should also entail a brief description of the roles of the various "team" members during the operative procedure. There are well-recognized complications associated with the various surgical procedures for the treatment of epilepsy. Further, there are predictable deficits following some of these procedures, some of which might be permanent and some of which may be transient. These pitfalls are briefly discussed.

Historical vignette: cerebral cortical stimulation and surgery for epilepsy.

In 1909, in an isolated community hospital, on the northern tip of the Province of Newfoundland and Labrador, Canada, Dr. John Mason Little, Jr. performed electrical stimulation of the cerebral cortex, prior to cortical excision, as treatment of recurrent cerebral seizures in three patients. Extracts from Dr. Little's written records of the clinical features, the neurosurgical procedures and cerebral cortical stimulation are summarised. A brief review of the contemporaneous history of neurosurgical procedures for epilepsy provides a prospective of Dr. Little's remarkable surgical virtuosity.

Cervical myelopathy secondary to ossification of the posterior longitudinal ligament in a Caucasian patient.

Cervical myelopathy consequent on ossification of posterior longitudinal ligament (OPLL) is very rare in Caucasians. A 65-year-old Anglo-Saxon woman developed progressive gait disturbance, paresthesia in both legs and urinary urge incontinence. Radiological examination showed OPLL from fifth to seventh cervical vertebral level; the dense OPLL was graphically displayed by three-dimensional computerized tomography. Medial corpectomy, C5 to C7, and removal of OPLL, with subsequent fusion C4 to T1 using a free fibula graft resulted in clinical improvement. Three dimensional computerized tomographic imaging is a valuable diagnostic procedure in OPLL.

The impact of spina bifida on the medical services of Newfoundland and Labrador.

This institution receives all live spina bifida patients from Newfoundland and Labrador. The aim of this study is to determine the outcome of these patients and the impact on the medical system. On a retrospective chart review, 274 patients born between 1967 and 1990 were studied. An analysis of the statistical variables showed that the incidence per 1,000 live births has remained stationary in Newfoundland and Labrador; there is a slight female predominance; 64% were born to young mothers and the peak incidence occurred in March, April, and May. A total of 179 patients of 254 who underwent surgery were alive and underwent rehabilitation programmes. Only 35% are wheelchair bound; the rest are ambulatory. One hundred sixty-one are of school age or older, 78 are in regular high school (3 dropouts), 36 are in special education, 6 graduated from high school, 4 are in university, 15 had no neurological deficit, 7 were lost in follow-up, 5 died, 9 had gross mental retardation, and 1 is the mother of three normal children. To attain these results these patients had multiple admissions and surgical procedures and the patients are seen twice a year in a rehabilitation and multidisciplinary clinic. From this study, the utilization of the medical services and impact on the community is great. However, the majority of these patients appear to attain a surprisingly high quality of life.

Psychosexual and psychosocial sequelae of closed head injury.

A series of 36 patients who had been hospitalized following closed head injury (CHI) were followed up 4.06 (SD 3.71) years after the injury. Measures were taken of degree of psychosexual dysfunction (Golombok Rust Inventory of Sexual Satisfaction-GRISS), general psychiatric morbidity (General Health Questionnaire-GHQ), and clinical anxiety and depression (Hospital Anxiety and Depression Scale-HAD). These measures were completed by patients and partners. Resulting data revealed that 50% of male patients with current sexual partners produced psychosexual profiles that fell within the dysfunctional range. For both male patients and their partners, the chief psychosexual complaint was infrequency. Of the patients studied, 61% were classified (using the GHQ) as having degrees of emotional distress that would fall within the range of psychiatric 'caseness', while 25% of patients achieved HAD criteria for clinical anxiety and 22% met HAD criteria for depression. Of the partners, 41% met GHQ criteria for psychiatric 'caseness', 18% being classified using the HAD as anxiety cases and 6% as depression cases. No effects of severity of injury were observed on any of the main outcome measures. Age and time since injury were related to measures of psychosexual dysfunction. These results are discussed in relation to the existing literature on psychosocial outcome in closed head injury, and recommendations for therapeutic intervention are made.

Hemifacial spasm and craniovertebral anomaly.

Two patients with congenital anomaly of the craniovertebral junction causing disabling hemifacial spasm (HFS) are presented. In one patient, complete cessation of the HFS occurred for a period of two years following simple bony decompression of the craniovertebral junction raising unanswered questions as to the exact pathogenesis of HFS. Eventually both patients required microvascular decompression at the root entry zone of the facial nerve.

Primary malignant tumours of the trigeminal nerve.

We report a case of primary malignant schwannoma of the trigeminal nerve, and review the 5 previously reported cases. Clinical presentation, along with radiological and pathological features are discussed.