Sub-6 nm Palladium Nanoparticles for Faster, More Sensitive H2 Detection Using Carbon Nanotube Ropes.

Palladium (Pd) nanoparticle (NP)-decorated carbon nanotube (CNT) ropes (or CNT@PdNP) are used as the sensing element for hydrogen gas (H2) chemiresistors. In spite of the fact that Pd NPs have a mean diameter below 6 nm and are highly dispersed on the CNT surfaces, CNT@PdNP ropes produce a relative resistance change 20-30 times larger than is observed at single, pure Pd nanowires. Thus, CNT@PdNP rope sensors improve upon all H2 sensing metrics (speed, dynamic range, and limit-of-detection), relative to single Pd nanowires which heretofore have defined the state-of-the-art in H2 sensing performance. Specifically, response and recovery times in air at [H2] ≈ 50 ppm are one-sixth of those produced by single Pd nanowires with cross-sectional dimensions of 40 × 100 nm Pd. The LODH2 is <10 ppm versus 300 ppm, and the dynamic range (10 ppm -4%) is nearly twice that afforded by the Pd nanowire. CNT@PdNP rope sensors are prepared by the dielectrophoretic deposition of a single semiconducting CNT rope followed by the electrodeposition of Pd nanoparticles with mean diameters ranging from 4.5 (±1) nm to 5.8 (±3) nm. The diminutive mean diameter and the high degree of diameter monodispersity for the deposited Pd nanoparticles are distinguishing features of the CNT@PdNP rope sensors described here, relative to prior work on similar systems.

Electrodeposited, Transverse Nanowire Electroluminescent Junctions.

The preparation by electrodeposition of transverse nanowire electroluminescent junctions (tn-ELJs) is described, and the electroluminescence (EL) properties of these devices are characterized. The lithographically patterned nanowire electrodeposition process is first used to prepare long (millimeters), linear, nanocrystalline CdSe nanowires on glass. The thickness of these nanowires along the emission axis is 60 nm, and the width, wCdSe, along the electrical axis is adjustable from 100 to 450 nm. Ten pairs of nickel-gold electrical contacts are then positioned along the axis of this nanowire using lithographically directed electrodeposition. The resulting linear array of nickel-CdSe-gold junctions produces EL with an external quantum efficiency, EQE, and threshold voltage, Vth, that depend sensitively on wCdSe. EQE increases with increasing electric field and also with increasing wCdSe, and Vth also increases with wCdSe and, therefore, the electrical resistance of the tn-ELJs. Vth down to 1.8(±0.2) V (for wCdSe ≈ 100 nm) and EQE of 5.5(±0.5) × 10(-5) (for wCdSe ≈ 450 nm) are obtained. tn-ELJs produce a broad EL emission envelope, spanning the wavelength range from 600 to 960 nm.

Visual improvement following intravitreal bevacizumab (Avastin) in exudative age-related macular degeneration.

PURPOSE: To study the visual and anatomic outcome of intravitreal bevacizumab injection in the treatment of exudative age-related macular degeneration (AMD). METHODS: Retrospective review of patients who received one or more intravitreal bevacizumab injections for exudative AMD. Outcome measures include standardized visual acuity, optical coherence tomography (OCT), macular thickness and volume, intraocular pressure, and blood pressure at 24 or more weeks follow-up. RESULTS: Fifty eyes of 48 patients were identified. Patients were observed for a median length of follow-up of 34 weeks (range, 24-50 weeks). Thirty-six eyes (72%) had prior treatment with pegaptanib (Macugen) and/or photodynamic therapy (PDT) and 14 eyes (28%) were treatment-naive. Mean visual acuity increased by 6.5 letters (P < 0.01) at 4 weeks and 5.3 letters (P < 0.01) at 24 weeks after initial bevacizumab injection. At 24 weeks, naive eyes had a mean increase of 14.2 letters (P < 0.001) and previously treated eyes had a mean increase of 2.8 letters (P = 0.06). Overall, mean OCT macular thickness and volume decreased by 73 micro m (P < 0.001) and 1.0 mm3 (P < 0.001) respectively at last follow-up. At last follow-up, all eyes received an average of 3.5 injections and experienced an average of 1.08 recurrences. There was no incidence of severe vision loss or adverse effect. CONCLUSION: Intravitreal bevacizumab has the potential for improvement in vision in both naive and previously treated eyes for at least 6 months. The benefit is more pronounced in eyes without prior pegaptanib and/or PDT.

Retinal tears and retinal detachment as factors affecting visual outcome after cataract extraction complicated by posteriorly dislocated lens material.

PURPOSE: To evaluate the incidence and effect on visual acuity of complicating factors such as retinal tears (RTs) and rhegmatogenous retinal detachment (RRD) in eyes with posteriorly dislocated lens fragments after cataract extraction. METHODS: Retrospective consecutive series of patients presenting at a referral vitreoretinal practice with posteriorly dislocated lens material after cataract extraction over a period of 8 years. The presence of RT, RRD, endophthalmitis, and choroidal hemorrhage was noted, and their effect on visual outcome was studied. RESULTS: A total of 307 eyes with posteriorly dislocated lens material after cataract extraction were identified. Fifty-eight eyes (19%) were managed medically (Group I), whereas the other 249 eyes (81%) underwent pars plana vitrectomy for removal of the lens material (Group II). Indications for surgical management included uncontrolled inflammation, elevated intraocular pressure, and large lens fragments. No eyes in Group I developed RT or RRD. Of the 249 Group II eyes, 13 (5%) were found to have RT, and 25 (10%) developed RRD. In Group II, choroidal hemorrhage and endophthalmitis were noted in 12 (5%) and 4 (2%) eyes, respectively. Fifty-one (88%) of 58 eyes in Group I and 138 (55%) of 249 eyes in Group II achieved a final visual acuity of 20/40 or better. Seven (54%) of the 13 eyes with RT and 9 (36%) of the 25 eyes with RRD achieved a final visual acuity of 20/40 or better. In the RRD group, 9 (56%) of the 16 macula-on eyes achieved a final visual acuity of 20/40 or better, whereas none of the 9 macula-off eyes had a final visual acuity of 20/40 or better. None of the 4 eyes with endophthalmitis and only 1 (8%) of the 12 eyes with choroidal hemorrhage had a final visual acuity of 20/40 or better. Five (62%) of eight eyes with retinal detachment treated with pneumatic retinopexy needed further treatment with scleral buckle to achieve anatomical reattachment. CONCLUSION: A good visual outcome (20/40 or better) is possible in eyes with posteriorly dislocated lens fragments after cataract extraction, even when retinal tears or macula-on retinal detachment is present. The presence of a macula-off retinal detachment, however, has a significant adverse effect on the visual outcome. Pneumatic retinopexy is not associated with retinal reattachment in many cases and is not preferred.

A new species of Triatominae from Tamil Nadu, India.

A new species of the genus Linshcosteus Distant, 1904 (Hemiptera: Reduviidae: Triatominae) is described from specimens collected near Kalakkadu, Tamil Nadu state, southern India. Specimens were found in deep crevices between rocks, in a region of semi-arid scrub jungle. The distinctiveness of the new species was demonstrated by a morphometric analysis including the five previously described species of Linshcosteus, all from India. Nine measurements of the head were used in an isometric size-free principal component analysis. In terms of discrete morphology the new species, Linshcosteus karupus sp.n. Galvão, Patterson, Rocha & Jurberg differs from the most similar one, L. kali Lent & Wygodzinsky, 1979, by its very prominent anterolateral projections of the pronotum, by the length to width ratio of the pronotum, by the pilosity of the head and several other characters, including phallic structures. A revised key is presented for the six species of the genus.

Flail Aortic Valve in Systemic Lupus Erythematosus: Diagnosis by Transesophageal Echocardiography.

This case report describes a patient with systemic lupus erythematosus who demonstrated by transesophageal echocardiography (TEE) a flail right coronary cusp of the aortic valve causing severe aortic regurgitation. This finding was confirmed at surgery, which showed near detachment of the right coronary leaflet near the commissure. Destruction of areas of the aortic valve has been reported in one previous case report in the absence of infective endocarditis or a traumatic process. This is the second case to our knowledge and the first to describe identification by TEE. (ECHOCARDIOGRAPHY, Volume 13, July 1996)