Ion-exchange and electrochemical properties of tetra-t-alkylferrocenium monolayers on gold electrodes.

Includes bibliographical references (p.98-108).Five penta-substituted ferrocenes, each having one 11-SH-undecanoyl substituent, have been prepared from 1,1′,3,3′-tetra-t-alkylferrocenes and attached as electrochemically-assembled monolayers to gold electrodes (t-alkyl = t-butyl (tetra-talkylferrocene = BUT-SH), 2-methyl-2-butyl (PENT-SH), 2-methyl-2-pentyl (HEX-SH), 2-methyl-2-hexyl (HEP-SH), and 2-methyl-2-nonyl (DEC-SH)). Cyclic voltammetry E1/2 values determined for the Au/S-Fc+/0 redox couples in aqueous 0.1 M H2SO4 decreased significantly in the order shown when the electrolyte also contained 0.001 M of the anions NO3– > BF4– > CF3SO3– > ClO4– > ReO4 – > PF6– > perfluorooctanesulfonate(PFOS–). The largest ΔE1/2(X−) was greater than 0.5 V and was observed for the Au/SDEC+/0 couple in 0.1 M H2SO4/0.001 M PFOS− relative to 0.1 M H2SO4 with no added anion. Additionally, for each of the 0.001 M added anions ΔE1/2(X−) became greater in the order Au/S-BUT+/0 < Au/S-PENT+/0 < Au/S-HEX+/0 < Au/S-HEP+/0 ≤ Au/S-DEC+/0. Equilibrium constants derived from ΔE1/2(HSO4–/X–) values suggest that differences in the electrochemical behavior for the five Au/S-Fc+/0 redox couples are manifestation of changes in the local dielectric constant surrounding Au/S-Fc+X– ion pairs. The novel ionexchange selectivity of Au/S-HEP+/0 monolayers has been exploited to accomplish selective amperometric determination of part per billion levels of the emerging environmental contaminants PFOS– and perfluorooctanoic acid (PFOA) in aqueous mixtures. Finally, idealized electrode array outputs, derived from hydrodynamic voltammograms charted for each of the five Au/S-Fc+/0 monolayers from flow-injection data, demonstrate unique amperometric responses for structurally similar perfluorinated compounds: PFOS−, perfluorooctanoic acid (PFOA) and tetradecafluoroheptanoic acid. Unique current signatures are also demonstrated for structurally similar anions ClO4 − and ReO4−. Collectively, these data demonstrate strong potential for a biologically-inspired sensing approach for interrogation of complex aqueous mixtures.by Natali Parisi.Ph.D

Design and Parametrical Analysis of Metamaterial Stacks in the Visible Spectral Range

Recently, the fabrication and optimization of nano-hole arrays in noble metal layers have attracted much attention both because of the interesting new physics associated with them and for their potential applications in nano-optics and biosensing. In particular nano-hole arrays in metal-dielectric-metal stacks, also known as "fish-net" type structures, are nowadays the best candidates to accomplish some suggestive physical phenomena like negative refractive index. Here we report a design and a parametrical analysis of a fishnet in the optical spectral range. In particular the dependence of both the magnetic and the electric resonance on the geometric features of the fishnet is investigated

δ-Aminolevulinic acid dehydratase single nucleotide polymorphism 2 (ALAD2) and peptide transporter 2*2 haplotype (hPEPT2*2) differently influence neurobehavior in low-level lead exposed children

Delta-aminolevulinic acid dehydratase single nucleotide polymorphism 2 (ALAD2) and peptide transporter haplotype 2*2 (hPEPT2*2) through different pathways can increase brain levels of delta-aminolevulinic acid and are associated with higher blood lead burden in young children. Past child and adult findings regarding ALAD2 and neurobehavior have been inconsistent, and the possible association of hPEPT2*2 and neurobehavior has not yet been examined. Mean blood lead level (BLL), genotype, and neurobehavioral function (fine motor dexterity, working memory, visual attention and short-term memory) were assessed in 206 males and 215 females ages 5.1–11.8 years. Ninety-six percent of children had BLLs \u3c 5.0 μg/dl. After adjusting for covariates (sex, age and mother\u27s level of education) and sibling exclusion (N = 252), generalized linear mixed model analyses showed opposite effects for the ALAD2 and hPEPT2*2 genetic variants. Significant effects for ALAD2 were observed only as interactions with BLL and the results suggested that ALAD2 was neuroprotective. As BLL increased, ALAD2 was associated with enhanced visual attention and enhanced working memory (fewer commission errors). Independent of BLL, hPEPT2*2 predicted poorer motor dexterity and poorer working memory (more commission errors). BLL alone predicted poorer working memory from increased omission errors. The findings provided further substantiation that (independent of the genetic variants examined) lowest-level lead exposure disrupted early neurobehavioral function, and suggested that common genetic variants alter the neurotoxic potential of low-level lead. ALAD2and hPEPT2*2 may be valuable markers of risk, and indicate novel mechanisms of lead-induced neurotoxicity. Longitudinal studies are needed to examine long-term influences of these genetic variants on neurobehavior

δ-Aminolevulinic acid dehydratase single nucleotide polymorphism 2 and peptide transporter 2*2 haplotype may differentially mediate lead exposure in male children

Child low-level lead (Pb) exposure is an unresolved public health problem and an unaddressed child health disparity. Particularly in cases of low-level exposure, source removal can be impossible to accomplish, and the only practical strategy for reducing risk may be primary prevention. Genetic biomarkers of increased neurotoxic risk could help to identify small subgroups of children for early intervention. Previous studies have suggested that, by way of a distinct mechanism, δ-aminolevulinic acid dehydratase single nucleotide polymorphism 2 (ALAD2) and/or peptide transporter 2*2 haplotype (hPEPT2*2) increase Pb blood burden in children. Studies have not yet examined whether sex mediates the effects of genotype on blood Pb burden. Also, previous studies have not included blood iron (Fe) level in their analyses. Blood and cheek cell samples were obtained from 306 minority children, ages 5.1 to 12.9 years. 208Pb and 56Fe levels were determined with inductively coupled plasma–mass spectrometry. General linear model analyses were used to examine differences in Pb blood burden by genotype and sex while controlling for blood Fe level. The sample geometric mean Pb level was 2.75 μg/dl. Pb blood burden was differentially higher in ALAD2 heterozygous boys and hPEPT2*2 homozygous boys. These results suggest that the effect of ALAD2 and hPEPT2*2 on Pb blood burden may be sexually dimorphic. ALAD2 and hPEPT2*2 may be novel biomarkers of health and mental health risks in male children exposed to low levels of Pb

Fabrication of metamaterials in the optical spectral range

Recently, the fabrication and optimization of nano-hole arrays in multi-layers has attracted much attention for their interesting applications in nano-optics and biosensing. In particular nano-hole arrays in metal-dielectric-metal stacks, also known as "fish-net" type structures, actually are the best candidates to accomplish some suggestive physical phenomena like negative refractive index, super-lensing and invisibility cloaks in the optical spectral range. Here, we report our preliminary results on the nanofabrication of "fish-net" type Au/dielectric/Au metamaterial stacks. Nano-hole arrays have been realized on Au (30 nm)-dielectric (50 nm)-Au (30 nm)/ITO stacks by means of direct ion milling with FIB using a FEI Nova 600i instrument. Finite element method (FEM) simulations were used to design the structures and to foresee their optical behavior. (C) 2010 Elsevier B.V. All rights reserved

Antitumor activity of epigenetic immunomodulation combined with CTLA-4 blockade in syngeneic mouse models

The multifaceted immunomodulatory activity of DNA hypomethylating agents improves immunogenicity and immune recognition of neoplastic cells; thus, we predicted they could be utilized to design new immunotherapeutic combinations in cancer. Testing this hypothesis, the antitumor efficacy of the DNA hypomethylating agent 5-aza-2'-deoxycytidine (5-AZA-CdR) combined with the anti-CTLA-4 monoclonal antibody (mAb) 9H10 in syngeneic transplantable murine models was investigated. Murine mammary carcinoma TS/A or mesothelioma AB1 cells were injected in BALB/c, athymic nude, and SCID/Beige mice that were treated with 5-AZA-CdR, mAb 9H10, or their combination. Tumor volumes were captured at different time-points; molecular and immunohistochemical assays investigated changes in neoplastic and normal tissues. A significant antitumor effect of 5-AZA-CdR combined with mAb 9H10 was found: compared to controls, a 77% (p &lt; 0.01), 54% (p &lt; 0.01) and 33% (p = 0.2) decrease in TS/A tumor growth was induced by 5-AZA-CdR combined with mAb 9H10, 5-AZA-CdR or mAb 9H10, respectively. These antitumor activities were confirmed utilizing the AB1 model. 5-AZA-CdR-based regimens induced a promoter-demethylation-sustained tumor expression of cancer testis antigens. MHC class I expression was up-regulated by 5-AZA-CdR. Antitumor efficacy of 5-AZA-CdR in athymic nude and SCID/Beige mice was not increased by mAb 9H10. In BALB/c mice, combined treatment induced the highest tumor infiltration by CD3(+) lymphocytes, which included both CD8(+) and CD4(+) T cells; no such infiltrates were observed in normal tissues. This significant immune-related antitumor activity of 5-AZA-CdR combined with CTLA-4 blockade, demonstrated in highly aggressive mouse tumor models, provides a strong scientific rationale to implement epigenetically-based immunotherapies in cancer patients

Effect of stocking density on growth and survival of juvenile Manila clams (Ruditapes philippinarum) farmed in suspended lanterns in a North Italian lagoon

To evaluate the effect of stocking density on pre-fattening growth and survival, Manila clam seeds from three different batches (B1, B2, and B3) were farmed in plastic net lanterns at two sites (western and northern) in Sacca degli Scardovari (Italy). Different stocking densities were compared, i.e. EXTRA (50,000 clams m-2), HIGH (30,000), and MEDIUM (20,000) for B1 and B2 clams; HIGH, MEDIUM, and LOW (10,000 clams m-2) for B3 clams. At the end of pre-fattening at the western site, the shell length decreased with increasing stocking density of both B1 (14.2 mm vs. 13.6 mm vs. 12.9 mm at HIGH vs. MEDIUM vs. EXTRA density; P < 0.001) and B2 (14.9 mm vs. 13.6 mm vs. 12.5 mm at MEDIUM vs. HIGH vs. EXTRA density; P < 0.001) clams. At the northern site, the shell length decreased in the following manner: MEDIUM to HIGH to EXTRA density for B1 clams (P < 0.001) and MEDIUM to EXTRA to HIGH density for B2 clams (P < 0.001). The same trend was recorded for B3 clams at both western (16.1 mm vs. 14.3 mm vs. 12.7 mm at LOW vs. MEDIUM vs. HIGH density; P < 0.001) and northern (15.6 mm vs. 13.9 mm vs. 13.2 mm; P < 0.001) sites. The stocking density did not affect the survival rate at the northern site and of the B3 clams, whereas the survival rate significantly decreased from MEDIUM and HIGH to EXTRA density for B1 (84.8 % and 85.4 % vs. 52.8 %; P < 0.05) and B2 (92.5 % and 87.6 % vs. 67.0 %; P < 0.01) clams at the western site where pre-fattening ended one week later than at the northern site. In the present conditions, clams in suspended lanterns reached the minimum sowing size (shell length 11 mm, weight 0.3 g) in 10 weeks. However, an increase in stocking density decreased clam growth and drastically increased mortality when water conditions became less favourable