Miles of Public Roads in Iowa by Surface Type, December 31, 2009

Public roads by surface type in Iowa by Iowa Department of Transportation.

Ocular gene therapy: a review of nonviral strategies.

Along with viral vectors, non-viral strategies have been developed in order to efficiently deliver nucleic acids to ocular cells. During the last decade, we have observed that the outcome of these non-viral delivery systems depends on the genetic material used, the targeted tissue or cells, the expected effect duration, and the routes of administration. Assessment of efficiency has been evaluated in normal eyes or in animal models of ocular diseases. The chemical and physical methods that have been adapted for the delivery of nucleic acids to ocular tissues are highlighted and discussed in this review. Also, the results obtained with different non-viral strategies from their initial conception to their present development are summarized. At the present, selective targeting of ocular tissues and cells can be achieved using the most yielding route of administration to the eye in combination with an appropriate drug delivery technique.

Ab initio study of NOx compounds adsorption on SnO2 surface

An ab initio study of the adsorption processes on NOx compounds on (1 1 0) SnO2 surface is presented with the aim of providing theoretical hints for the development of improved NOx gas sensors. From first principles calculations (DFT¿GGA approximation), the most relevant NO and NO2 adsorption processes are analyzed by means of the estimation of their adsorption energies. The resulting values and the developed model are also corroborated with experimental desorption temperatures for NO and NO2, allowing us to explain the temperature-programmed desorption experiments. The interference of the SO2 poisoning agent on the studied processes is discussed and the adsorption site blocking consequences on sensing response are analyzed.

Surface states in template synthesized tin oxide nanoparticles

Tin-oxide nanoparticles with controlled narrow size distributions are synthesized while physically encapsulated inside silica mesoporous templates. By means of ultraviolet-visible spectroscopy, a redshift of the optical absorbance edge is observed. Photoluminescence measurements corroborate the existence of an optical transition at 3.2 eV. The associated band of states in the semiconductor gap is present even on template-synthesized nanopowders calcined at 800°C, which contrasts with the evolution of the gap states measured on materials obtained by other methods. The gap states are thus considered to be surface localized, disappearing with surface faceting or being hidden by the surface-to-bulk ratio decrease.

Leishmania major: differential regulation of the surface metalloprotease in amastigote and promastigote stages.

During its life cycle, the protozoan parasite Leishmania major alternates from an intracellular amastigote form in the mammalian host to a flagellated promastigote form in the insect vector. The expression of the surface metalloprotease (PSP) during differentiation in vitro was investigated by Western and Northern blots, by immunoprecipitation of cells metabolically labeled with [35S]methionine or labeled at the surface with radioactive iodine, and by quantification of the proteolytic activity in substrate-containing polyacrylamide gels. We report that the surface metalloprotease is down-regulated at both the mRNA and the protein level in amastigotes, where it represents less than 1% of the equivalent proteolytic activity detected in promastigotes. A significant amount of mRNA is detected 4 hr after the onset of differentiation. The expression of the protease begins at that time and reaches steady state 8 hr later. The synthesis of PSP precedes the complete morphological differentiation to the promastigote stage and the appearance of the lipophosphoglycan, another major promastigote surface component. In contrast to PSP, a family of mercaptoethanol-activated proteases present in the amastigote exists only at a reduced level in the promastigote. The confinement of the surface metalloprotease to the insect stage of the parasite suggests that it has no physiological function in the parasitism maintenance of mammalian host macrophages.

Carboxyl terminus structural requirements for glycosyl-phosphatidylinositol anchor addition to cell surface proteins.

Glycosyl phosphatidylinositol (GPI)-anchored proteins contain in their COOH-terminal region a peptide segment that is thought to direct glycolipid addition. This signal has been shown to require a pair of small amino acids positioned 10-12 residues upstream of an hydrophobic C-terminal domain. We analysed the contribution of the region separating the anchor acceptor site and the C-terminal hydrophobic segment by introducing amino acid deletions and substitutions in the spacer element of the GPI-anchored Thy-1 glycoprotein. Deletions of 7 amino acids in this region, as well as the introduction of 2 charged residues, prevented the glycolipid addition to Thy-1, suggesting that the length and the primary sequence of the spacer domain are important determinants in the signal directing GPI anchor transfer onto a newly synthesized polypeptide. Furthermore, we tested these rules by creating a truncated form of the normally transmembranous Herpes simplex virus I glycoprotein D (gDI) and demonstrating that when its C-terminal region displays all the features of a GPI-anchored protein, it is able to direct glycolipid addition onto another cell surface molecule.

Influence of premetallization surface treatment on the formation of Schottky Au-nGaN contacts

The influence of premetallization surface preparation on the structural, chemical, and electrical properties of Au-nGaN interfaces has been investigated by x-ray photoemission spectroscopy (XPS), current-voltage measurement (I-V) and cross-section transmission electron microscopy (TEM). XPS analysis showed that the three GaN substrate treatments investigated i.e., ex situ hydrofluoric acid etch, in situ anneal in ultrahigh-vacuum (UHV), and in situ Ga reflux cleaning in UHV result in surfaces increasingly free of oxygen contamination. XPS and TEM characterization of Au-nGaN formed after the three premetallization surface treatments show that HF etching and UHV annealing produce abrupt, well-defined interfaces. Conversely, GaN substrate cleaning in a Ga flux results in Au/GaN intermixing. I-V characterization of Au¿nGaN contacts yields a Schottky barrier height of 1.25 eV with a very low-ideality factor and very good contact uniformity for the premetallization UHV anneal, while the Ga reflux cleaning results in a much lower barrier (0.85 eV), with poor ideality and uniformity. I-V and XPS results suggest a high density of acceptor states at the surface, which is further enhanced by UHV annealing. These results are discussed in the context of current models of Schottky barrier formation.

Recurrent paroxysmal fever revealing ocular syphilis.

An increased prevalence of ocular syphilis has been reported in recent years reflecting a trend towards liberalisation of sexual practices in the era of Highly Active Anti-retroviral Treatment for HIV infection [1][2]. In view of the protean nature of the disease, pathognomonic features that could guide differential diagnosis of ocular inflammation towards syphilis are lacking. Ocular involvement can antedate or follow systemic manifestations of syphilitic infection, ranging widely and potentially involving all ocular tissue [3][4]. We report here an unusual case of chronic fever and fatigue the cause of which remained elusive for a period of three years, despite extensive investigations, until the development of bilateral panuveitis, raising the suspicion of syphilitc infection.

Analysis of micro- and nano-structures of the corneal surface of Drosophila and its mutants by atomic force microscopy and optical diffraction.

Drosophila melanogaster is a model organism instrumental for numerous biological studies. The compound eye of this insect consists of some eight hundred individual ommatidia or facets, ca. 15 µm in cross-section. Each ommatidium contains eighteen cells including four cone cells secreting the lens material (cornea). High-resolution imaging of the cornea of different insects has demonstrated that each lens is covered by the nipple arrays--small outgrowths of ca. 200 nm in diameter. Here we for the first time utilize atomic force microscopy (AFM) to investigate nipple arrays of the Drosophila lens, achieving an unprecedented visualization of the architecture of these nanostructures. We find by Fourier analysis that the nipple arrays of Drosophila are disordered, and that the seemingly ordered appearance is a consequence of dense packing of the nipples. In contrast, Fourier analysis confirms the visibly ordered nature of the eye microstructures--the individual lenses. This is different in the frizzled mutants of Drosophila, where both Fourier analysis and optical imaging detect disorder in lens packing. AFM reveals intercalations of the lens material between individual lenses in frizzled mutants, providing explanation for this disorder. In contrast, nanostructures of the mutant lens show the same organization as in wild-type flies. Thus, frizzled mutants display abnormal organization of the corneal micro-, but not nano-structures. At the same time, nipples of the mutant flies are shorter than those of the wild-type. We also analyze corneal surface of glossy-appearing eyes overexpressing Wingless--the lipoprotein ligand of Frizzled receptors, and find the catastrophic aberration in nipple arrays, providing experimental evidence in favor of the major anti-reflective function of these insect eye nanostructures. The combination of the easily tractable genetic model organism and robust AFM analysis represents a novel methodology to analyze development and architecture of these surface formations.

Measurement of Pavement Surface Variations, July 1974

The measurement of pavement roughness has been the concern of highway engineers for more than 70 years. This roughness is referred to as "riding quality" by the traveling public. Pavement roughness evaluating devices have attempted to place either a graphical or numerical value on the public's riding comfort or discomfort. Early graphical roughness recorders had many different designs. In 1900 an instrument called the "Viagraph" was developed by an Irish engineer.' The "Viagraph" consisted of a twelve foot board with graphical recorder drawn over the pavement. The "Profilometer" built in Illinois in 1922 was much more impressive. ' The instrument's recorder was mounted on a frame supported by 32 bicycle wheels mounted in tandem. Many other variations of profilometers with recorders were built but most were difficult to handle and could not secure uniformly reproducible results. The Bureau of Public Roads (BPR) Road Roughness Indicator b u i l t in 1941 is the most widely used numerical roughness recorder.' The BPR Road Roughness Indicator consists of a trailer unit with carefully selected springs, means of dampening, and balanced wheel.

Temporal variability of soil water content under different surface conditions in the semiarid region of the Pernambuco state

Rainfall in the semiarid region of Pernambuco is characterized by irregular distribution in time and space, which significantly hinders the rainfed agriculture in the region. This work aims to evaluate the temporal profile of soil moisture in the semiarid region of the Pernambuco State (Brazil) and the effect of different soil surface conditions on soil water content variation and the yield of rainfed beans. To monitor soil water content, five plots 4.5 m wide by 11 m long were installed in a Yellow Argisol (Ultisol). The following treatments were adopted in the experimental plots: natural vegetation, bean intercropped with cactus, beans planted down the slope, beans planted along contour lines with mulch and rock barriers, and bare soil. In each plot, eight PVC access tubes were installed for monitoring the soil water content profile at depths of 0.20 and 0.40 m using a neutron probe device. The surface condition significantly influenced the soil water content variation, both in the dry and rainy seasons. The use of mulch, associated with rock barriers, provided higher soil water content levels than the other treatments and increased the rainfed beans production.

Surface collective oscillations of metal clusters and spheres: Random-phase-approximation sum-rules approach

Using the once and thrice energy-weighted moments of the random-phase-approximation strength function, we have derived compact expressions for the average energy of surface collective oscillations of clusters and spheres of metal atoms. The L=0 volume mode has also been studied. We have carried out quantal and semiclassical calculations for Na and Ag systems in the spherical-jellium approximation. We present a rather thorough discussion of surface diffuseness and quantal size effects on the resonance energies.

Comment on the plasmon model for image-potential-induced surface states

Calculations of the binding energy of bound positron states in metal surfaces, with explicit inclusion of plasmon dispersion and single-particle effects, are presented. The binding energy is greatly reduced with respect to the undispersed case.