Epitaxial growth of vertical GaAs nanowires on Si(111) substrates is demonstrated by metal-organic chemical vapor deposition via a vapor-liquid-solid growth mechanism. Systematic experiments indicate that substrate pretreatment, pregrowth alloying temperature, and growth temperature are all crucial to vertical epitaxial growth. Nanowire growth rate and morphology can be well controlled by the growth temperature, the metal-organic precursor molar fraction, and the molar V/III ratio. The as-grown GaAs nanowires have a predominantly zinc-blende crystal structure along a <111> direction. Crystallographic {111} stacking faults found perpendicular to the growth axis could be almost eliminated via growth at high V/III ratio and low temperature. Single nanowire field effect transistors based on unintentionally doped GaAs nanowires were fabricated and found to display a strong effect of surface states on their transport properties.

Introduction:In some cases, scleroderma renal crisis (SRC) is not easily distinguishable from other thrombotic microangiopathies such as thrombotic thrombocytopenic purpura, especially when the presentation includes neurological or extra-renal manifestations. Here, we present a case of SRC who developed a rare neurotoxic complication, posterior reversible encephalopathy syndrome (PRES).A 36-year-old man with a history of diffuse cutaneous systemic sclerosis developed SRC and acute-on-chronic renal failure and ultimately required maintenance hemodialysis. Three weeks after starting hemodialysis, the patient presented with confusion and a new-onset seizure disorder. Laboratory examinations revealed thrombocytopenia, a low haptoglobin level, and schizocytes on a blood smear. SRC-related PRES was considered first after PRES was confirmed by brain magnetic resonance imaging. Antihypertensive therapy comprising captopril and amlodipine was administered, and the patient experienced a complete neurological recovery 3 days later without plasma exchange. In all previously reported cases of SRC-associated PRES, PRES developed before hemodialysis. Our report is, therefore, the first to describe a case of onset of SRC-related PRES 3 weeks after the initiation of maintenance hemodialysis.Conclusion:This case demonstrates that microangiopathy and extra-renal manifestations can develop even in SRC patients with end-stage renal disease and that these manifestations can be successfully managed with angiotensin-converting enzyme inhibitors (ACEIs) and aggressive blood pressure control. We recommend continuing ACEI therapy if elevated blood pressure persists after maintenance hemodialysis.