Polymers offer unique avenues for the structural control of materials on the nanoscopic length scale for the production of nanoporous media, membranes, lithographic templates, and scaffolds for assemblies of electronic materials. [1±4] With structures on this length scale, quantum properties of electronic materials are exhibited even at elevated temperatures. The natural length scale of polymer chains and their morphologies in the bulk lie precisely at these length scales and, as such, there is a substantial effort to produce, characterize and use polymeric nanostructures. The ease of processing polymers adds to the attractiveness of polymer-based nanostructures. In comparison to the time-intensive process of sequential writing of nanoscale patterns, nanostructure formation by self-assembly is highly parallel and inherently fast. Block copolymers are ideal materials in this respect, since, due to the connectivity of two chemically distinct chains, the molecules self-assemble into ordered morphologies with a size scale limited to molecular dimensions. Of particular interest are block copolymers that form cylindrical microdomains, since the elimination of the minor component transforms the material into an array of nanopores.A prerequisite for the use of copolymers is the control over the orientation of the microdomains. In particular, for cylindrical microdomains, an orientation normal to the substrate surface is desirable. Two different approaches are used to this end. In thin films, random copolymers anchored to a substrate can be used to produce a neutral surface. [5] For entropic reasons, the microdomains orient normal to the substrate surface. [6] In a second approach, electric fields were used to orient the cylindrical microdomains parallel to the field lines. [7±10] The approach relies on the orientation-dependent polarization energy induced when an anisotropic body is placed in an electric field. An anisotropic microphase structure will orient such that the interfaces between the two blocks are aligned parallel to the electric field.In this article it is shown that cylindrical microdomains of a copolymer film can be used to generate an array of ordered nanoscopic pores with well-controlled size, orientation, and structure. To this end, selective etching procedures and a characterization of the samples by quantitative analysis of the X-ray scattering along with electron (EM) and atomic force microscopies (AFM) are described. The processes outlined are shown to be operative over a very large range in sample thickness ranging from 40 nm up to several micrometers. The resulting nanoporous films are promising candidates as membranes with specific transport properties and as templates for electronic and magnetic nanostructured materials. Figures 1A and 1B show AFM images obtained from a 40 nm±thick film prepared on a neutral substrate after annealing. Cylinders standing perpendicular to the substrate are clearly discernable, particularly in the phase image, since the height variations are very small. Polystyr...

Polymers offer unique avenues for the structural control of materials on the nanoscopic length scale for the production of nanoporous media, membranes, lithographic templates, and scaffolds for assemblies of electronic materials.[1±4] With structures on this length scale, quantumproperties of electronic materials are exhibited even at elevated temperatures. The natural length scale of polymer chains and their morphologies in the bulk lie precisely at these length scales and, as such, there is a substantial effort to produce, characterize and use polymeric nanostructures. The ease of processing polymers adds to the attractiveness of polymer-based nanostructures. In comparison to the time-intensive process of sequential writing of nanoscale patterns, nanostructure formation by self-assembly is highly parallel and inherently fast. Block copolymers are ideal materials in this respect, since, due to the connectivity of two chemically distinct chains, the molecules self-assemble into ordered morphologies with a size scale limited to molecular dimensions. Of particular interest are block copolymers that form cylindrical microdomains, since the elimination of the minor component transforms the material into an array of nanopores. A prerequisite for the use of copolymers is the control over the orientation of the microdomains. In particular, for cylindrical microdomains, an orientation normal to the substrate surface is desirable. Two different approaches are used to this end. In thin films, random copolymers anchored to a substrate can be used to produce a neutral surface.[5] For entropic reasons, the microdomains orient normal to the substrate surface.[6] In a second approach, electric fields were used to orient the cylindrical microdomains parallel to the field lines.[7±10] The approach relies on the orientation-dependent polarization energy induced when an anisotropic body is placed in an electric field. An anisotropic microphase structure will orient such that the interfaces between the two blocks are aligned parallel to the electric field. In this article it is shown that cylindrical microdomains of a copolymer film can be used to generate an array of ordered nanoscopic pores with well-controlled size, orientation, and structure. To this end, selective etching procedures and a characterization of the samples by quantitative analysis of the X-ray scattering along with electron (EM) and atomic force microscopies (AFM) are described. The processes outlined are shown to be operative over a very large range in sample thickness ranging from 40 nm up to several micrometers. The resulting nanoporous films are promising candidates as membranes with specific transport properties and as templates for electronic and magnetic nanostructured materials.Figures 1A and 1B show AFM images obtained from a 40 nm±thick film prepared on a neutral substrate after annealing. Cylinders standing perpendicular to the substrate are clearly discernable, particularly in the phase image, since the height variations are very small. Polystyrene (PS...

A surface covered with a nanopatterned, regularly spaced array of SiO2 blocksis obtained by coating silica with a block copolymer, selectively removing one polymer from the layer, depositing SiO2 in the voids, and finally degrading the second polymer. The Figure shows an AFM image of a finished sample. Rough surfaces of this type are very promising candidates for sensor and lab‐on‐a‐chip applications.

No abstract

Chemical control of the endohedral volume of single-wall carbon nanotubes (SWCNTs) via liquid-phase filling is established to be a facile strategy to controllably modify properties of SWCNTs in manners significant for processing and proposed applications.

Background and objectives The calcimimetic cinacalcet reduced the risk of death or cardiovascular (CV) events in older, but not younger, patients with moderate to severe secondary hyperparathyroidism (HPT) who were receiving hemodialysis. To determine whether the lower risk in younger patients might be due to lower baseline CV risk and more frequent use of cointerventions that reduce parathyroid hormone (kidney transplantation, parathyroidectomy, and commercial cinacalcet use), this study examined the effects of cinacalcet in older ($65 years, n=1005) and younger (,65 years, n=2878) patients.Design, setting, participants, & measurements Evaluation of Cinacalcet HCl Therapy to Lower Cardiovascular Events (EVOLVE) was a global, multicenter, randomized placebo-controlled trial in 3883 prevalent patients on hemodialysis, whose outcomes included death, major CV events, and development of severe unremitting HPT. The age subgroup analysis was prespecified.Results Older patients had higher baseline prevalence of diabetes mellitus and CV comorbidity. Annualized rates of kidney transplantation and parathyroidectomy were .3-fold higher in younger relative to older patients and were more frequent in patients randomized to placebo. In older patients, the adjusted relative hazard (95% confidence interval) for the primary composite (CV) end point (cinacalcet versus placebo) was 0.70 (0.60 to 0.81); in younger patients, the relative hazard was 0.97 (0.86 to 1.09). Corresponding adjusted relative hazards for mortality were 0.68 (0.51 to 0.81) and 0.99 (0.86 to 1.13). Reduction in the risk of severe unremitting HPT was similar in both groups. ConclusionsIn the EVOLVE trial, cinacalcet decreased the risk of death and of major CV events in older, but not younger, patients with moderate to severe HPT who were receiving hemodialysis. Effect modification by age may be partly explained by differences in underlying CV risk and differential application of cointerventions that reduce parathyroid hormone.

Coccidioidomycosis is a fungal disease with protean manifestations endemic to the Lower Sonoran Life Zone, which includes the hot deserts of the southwestern United States and areas of Mexico. Two hundred and twenty-three patients were found to have coccidioidomycosis at our institution from 1994-2002, the largest reported cohort of coccidioidomycosis patients since the 1950s. Of these patients, 58% presented with isolated pulmonary disease, 14% had high (>1:16) complement fixation titers without clear evidence of dissemination, 22% had definite disseminated disease, and 5% had unclassified disease. Enzyme immunoassay was a reliable diagnostic tool in those with symptomatic disease, but had a low specificity in those who were asymptomatic. Complement fixation titers of > or =1:16 were associated with dissemination to bone or skin but were not helpful in evaluating central nervous system disease. Thirteen percent of patients with high complement fixation titers (>1:16) without clear evidence of dissemination on presentation and 7% of those with isolated pulmonary disease eventually progressed to disseminated disease; 30% of Filipino patients with pulmonary disease progressed to disseminated disease. Nonwhite race was a predictor for dissemination; African American patients more often developed disseminated bony disease while Filipinos were more likely to develop cutaneous or central nervous system disease. Relapse of disseminated coccidioidomycosis occurred in 24% of patients; the risk was highest (71%) among those with central nervous system disease. Azole therapy was generally inferior to amphotericin B in disseminated disease. Predictors of permanent disability included African American or Filipino race, central nervous system disease, and bony disease.

The postcardiac injury syndrome (PCIS) includes the postmyocardial infarction syndrome, the postcommissurotomy syndrome, and the postpericardiotomy syndrome. Dressler reported a series of patients who developed a pericarditis-like illness days to weeks after a myocardial infarction. Postcardiac injury syndrome also has been observed after cardiac surgery, percutaneous intervention, pacemaker implantation, and radiofrequency ablation. Postcardiac injury syndrome is characterized by pleuritic chest pain, low-grade fever, an abnormal chest x-ray, and the presence of exudative pericardial and/or pleural effusions. The pathophysiology of PCIS involves auto-antibodies that target antigens exposed after damage to cardiac tissue. The treatment of PCIS includes the use of nonsteroidal anti-inflammatory drugs and corticosteroids. Prophylactic use of corticosteroids before cardiac surgery has not been effective in preventing PCIS. The widespread use of reperfusion therapy and cardiac medications with anti-inflammatory properties may have reduced the incidence of PCIS. Although PCIS can follow a relapsing course, it does carry a favorable prognosis.