Simultaneous determination of dopamine and ascorbic acid at an in-site functionalized self-assembled monolayer on gold electrode

The in-site functionalization of 4-aminothiophenol (4-ATP) self-assembled monolayer on gold electrode at physiological pH yields a redox active monolayer of 4'-mercapto-N-phenylquinone diimine (MNPD). The functionalized electrode exhibits excellent electrocatalytic responses towards dopamine (DA) and ascorbic acid (AA), reducing the overpotentials by about 0.22 V and 0.34 V, respectively, with greatly enhanced current responses. Due to its different catalytic activities toward DA and AA, the modified electrode resolves the overlapping voltammetric responses of DA and AA into two well-defined voltammetric peaks by differential pulse voltammetry (DPV), which can be used for the simultaneous determination of these species in a mixture. The catalytic peak current obtained from DPV was linearly related to DA and AA concentration in the ranges of 5.0 x 10-6 - 1.25 x 10-4 M and 8.0 x 10-6 - 1.3 x 10-4 M with correlation coefficient of 0.999 and 0.998, respectively. The detective limits (3sigma) for DA and AA were found to be 1.2 x 10-6 M and 2.4 x 10-6 M, respectively.

Site substitution and energy transfer of Eu2+ and Ce3+ in KMgF3 : Eu and KMgF3 : Eu-Ce single crystals

The high-resolution emission spectra of KMgF3 : Eu and KMgF3 : Eu-Ce single crystals were measured at 77 K. The site substitution of Eu2+ and Eu2+-Ce3+ co-doped system in KMgF3 was discussed. Eu2+ substituted for K+ sites on three different site-symmetry: cubic, trigonal and tetragonal. The attribution of all lines occurring in the emission spectra were ascertained. The indirect energy transfer from P-6(5/2) states of Eu2+ to 4f5d states of Ce3+ in KMgF3 : Eu-Ce was observed and the energy transfer mechanism was studied. The d-d interaction among levels was proposed.

Isolation, properties and spatial site analysis of gamma subunits of B-phycoerythrin and R-phycoerythrin

Polysiphonia urceolata R-phycoerythrin and Porphyridium cruentum B-phycoerythrin were degraded with proteinaseK, and then the nearly native gamma subunits were isolated from the reaction mixture. The process of degradation of phycoerythrin with proteinaseK showed that the gamma subunit is located in the central cavity of (alpha beta)(6) hexamer of phycoerythrin. Comparative analysis of the spectra of the native phycoerythrin, the phycoerythrin at pH 12 and the isolated gamma subunit showed that the absorption peaks of phycoerythrobilins on alpha or beta subunit are at 535 nm (or 545 nm) and 565 nm, the fluorescence emission maximum at 580 nm; the absorption peak of phycoerythrobilins on the isolated gamma subunit is at 589 nm, the fluorescence emission peak at 620 nm which overlaps the absorption maximum of C-phycocyanin and perhaps contributes to the energy transfer with high efficiency between phycoerythrin and phycocyanin in phycobilisome; the absorption maximum of phycourobilin on the isolated gamma subunit is at 498 nm, which is the same as that in native phycoerythrin, and the fluorescence emission maximum at 575 nm.

Element enrichment and U-series isotopic characteristics of the hydrothermal sulfides at Jade site in the Okinawa Trough

The geochemical and U-series isotopic characteristics of hydrothermal sulfide samples from the Jade site (127A degrees 04.5'E, 27A degrees 15'N, water depth 1300-1450 m) at Jade site in the Okinawa Trough were analyzed. In the hydrothermal sulfide samples bearing sulfate (samples HOK1 and HOK2), the LREEs are relatively enriched. All the hydrothermal sulfide samples except HOK1 belong to Zn-rich hydrothermal sulfide. In comparison with Zn-rich hydrothermal sulfides from other fields, the contents of Zn, Pb, Ag, Cd, Au and Hg are higher, the contents of Fe, Al, Cr, Co, Ni, Sr, Te, Cs, Ti and U lower, and the Pb-210 radioactivity ratios and Pb-210/Pb ratios very low. In the hydrothermal sulfide mainly composed of sphalerite, the correlations between rare elements Hf and U, and Hf and Mn as well as that between dispersive elements Ga and Zn, are strongly positive; also the contents of Au and Ag are related to Fe-sulfide, because the low temperature promotes enrichment of Au and Ag. Meanwhile, the positive correlations between Fe and Bi and between Zn and Cd are not affected by the change of mineral assemblage. Based on the Pb-210/Pb ratios of hydrothermal sulfide samples (3.99x10(-5)-5.42x10(-5)), their U isotopic composition (U-238 content 1.15-2.53 ppm, U-238 activity 1.07-1.87 dpm/g, U-234 activity 1.15-2.09 dpm/g and U-234/U-238 ratio 1.07-1.14) and their Th-232 and Th-230 contents are at base level, and the chronological age of hydrothermal sulfide at Jade site in the Okinawa Trough is between 200 and 2000 yr.

Evidence for the Flare Trigger Site and Three-Dimensional Reconnection in Multiwavelength Observations of a Solar Flare

Fletcher, L., Metcalf, T.R., Alexander, D., Brown, D.S. and Ryder, L.A., 2001, Evidence for the flare trigger site and 3D reconnection in multi-wavelength observations of a solar flare, Astrophysical Journal, 554, 451-463.

Pyramidal quantum dots: single and entangled photon sources and correlation studies

Practical realisation of quantum information science is a challenge being addressed by researchers employing various technologies. One of them is based on quantum dots (QD), usually referred to as artificial atoms. Being capable to emit single and polarization entangled photons, they are attractive as sources of quantum bits (qubits) which can be relatively easily integrated into photonic circuits using conventional semiconductor technologies. However, the dominant self-assembled QD systems suffer from asymmetry related problems which modify the energetic structure. The main issue is the degeneracy lifting (the fine-structure splitting, FSS) of an optically allowed neutral exciton state which participates in a polarization-entanglement realisation scheme. The FSS complicates polarization-entanglement detection unless a particular FSS manipulation technique is utilized to reduce it to vanishing values, or a careful selection of intrinsically good candidates from the vast number of QDs is carried out, preventing the possibility of constructing vast arrays of emitters on the same sample. In this work, site-controlled InGaAs QDs grown on (111)B oriented GaAs substrates prepatterned with 7.5 μm pitch tetrahedrons were studied in order to overcome QD asymmetry related problems. By exploiting an intrinsically high rotational symmetry, pyramidal QDs were shown as polarization-entangled photon sources emitting photons with the fidelity of the expected maximally entangled state as high as 0.721. It is the first site-controlled QD system of entangled photon emitters. Moreover, the density of such emitters was found to be as high as 15% in some areas: the density much higher than in any other QD system. The associated physical phenomena (e.g., carrier dynamic, QD energetic structure) were studied, as well, by different techniques: photon correlation spectroscopy, polarization-resolved microphotoluminescence and magneto-photoluminescence.

A cross-site, comparative effectiveness study of an integrated HIV and substance use treatment program.

Co-occurrence of HIV and substance abuse is associated with poor outcomes for HIV-related health and substance use. Integration of substance use and medical care holds promise for HIV patients, yet few integrated treatment models have been reported. Most of the reported models lack data on treatment outcomes in diverse settings. This study examined the substance use outcomes of an integrated treatment model for patients with both HIV and substance use at three different clinics. Sites differed by type and degree of integration, with one integrated academic medical center, one co-located academic medical center, and one co-located community health center. Participants (n=286) received integrated substance use and HIV treatment for 12 months and were interviewed at 6-month intervals. We used linear generalized estimating equation regression analysis to examine changes in Addiction Severity Index (ASI) alcohol and drug severity scores. To test whether our treatment was differentially effective across sites, we compared a full model including site by time point interaction terms to a reduced model including only site fixed effects. Alcohol severity scores decreased significantly at 6 and 12 months. Drug severity scores decreased significantly at 12 months. Once baseline severity variation was incorporated into the model, there was no evidence of variation in alcohol or drug score changes by site. Substance use outcomes did not differ by age, gender, income, or race. This integrated treatment model offers an option for treating diverse patients with HIV and substance use in a variety of clinic settings. Studies with control groups are needed to confirm these findings.

Polymorphisms at the microRNA binding-site of the stem cell marker gene CD133 modify susceptibility to and survival of gastric cancer.

CD133 is one of the most common stem cell markers, and functional single nucleotide polymorphisms (SNPs) of CD133 may modulate its gene functions and thus cancer risk and patient survival. We hypothesized that potentially functional CD133 SNPs are associated with gastric cancer (GC) risk and survival. To test this hypothesis, we conducted a case-control study of 371 GC patients and 313 cancer-free controls frequency-matched by age, sex, and ethnicity. We genotyped four selected, potentially functional CD133 SNPs (rs2240688A>C, rs7686732C>G, rs10022537T>A, and rs3130C>T) and used logistic regression analysis for associations of these SNPs with GC risk and Cox hazards regression analysis for survival. We found that compared with the miRNA binding site rs2240688 AA genotype, AC + CC genotypes were associated with significantly increased GC risk (adjusted OR = 1.52, 95% CI = 1.09-2.13); for another miRNA binding site rs3130C>T SNP, the TT genotype was associated with significantly reduced GC risk (adjusted OR = 0.68, 95% CI = 0.48-0.97), compared with CC + CT genotypes. In all patients, the risk rs3130 TT variant genotype was significantly associated with overall survival (OS) (adjusted P(trend) = 0.016 and 0.007 under additive and recessive models, respectively). These findings suggest that these two CD133 miRNA binding site variants, rs2240688 and rs3130, may be potential biomarkers for genetic susceptibility to GC and possible predictors for survival in GC patients but require further validation by larger studies.

Dramatic variability of the carbonate system at a temperate coastal ocean site (Beaufort, North Carolina, USA) is regulated by physical and biogeochemical processes on multiple timescales.

Increasing atmospheric carbon dioxide (CO2) from anthropogenic sources is acidifying marine environments resulting in potentially dramatic consequences for the physical, chemical and biological functioning of these ecosystems. If current trends continue, mean ocean pH is expected to decrease by ~0.2 units over the next ~50 years. Yet, there is also substantial temporal variability in pH and other carbon system parameters in the ocean resulting in regions that already experience change that exceeds long-term projected trends in pH. This points to short-term dynamics as an important layer of complexity on top of long-term trends. Thus, in order to predict future climate change impacts, there is a critical need to characterize the natural range and dynamics of the marine carbonate system and the mechanisms responsible for observed variability. Here, we present pH and dissolved inorganic carbon (DIC) at time intervals spanning 1 hour to >1 year from a dynamic, coastal, temperate marine system (Beaufort Inlet, Beaufort NC USA) to characterize the carbonate system at multiple time scales. Daily and seasonal variation of the carbonate system is largely driven by temperature, alkalinity and the balance between primary production and respiration, but high frequency change (hours to days) is further influenced by water mass movement (e.g. tides) and stochastic events (e.g. storms). Both annual (~0.3 units) and diurnal (~0.1 units) variability in coastal ocean acidity are similar in magnitude to 50 year projections of ocean acidity associated with increasing atmospheric CO2. The environmental variables driving these changes highlight the importance of characterizing the complete carbonate system rather than just pH. Short-term dynamics of ocean carbon parameters may already exert significant pressure on some coastal marine ecosystems with implications for ecology, biogeochemistry and evolution and this shorter term variability layers additive effects and complexity, including extreme values, on top of long-term trends in ocean acidification.

Interactions of chromatin context, binding site sequence content, and sequence evolution in stress-induced p53 occupancy and transactivation.

Cellular stresses activate the tumor suppressor p53 protein leading to selective binding to DNA response elements (REs) and gene transactivation from a large pool of potential p53 REs (p53REs). To elucidate how p53RE sequences and local chromatin context interact to affect p53 binding and gene transactivation, we mapped genome-wide binding localizations of p53 and H3K4me3 in untreated and doxorubicin (DXR)-treated human lymphoblastoid cells. We examined the relationships among p53 occupancy, gene expression, H3K4me3, chromatin accessibility (DNase 1 hypersensitivity, DHS), ENCODE chromatin states, p53RE sequence, and evolutionary conservation. We observed that the inducible expression of p53-regulated genes was associated with the steady-state chromatin status of the cell. Most highly inducible p53-regulated genes were suppressed at baseline and marked by repressive histone modifications or displayed CTCF binding. Comparison of p53RE sequences residing in different chromatin contexts demonstrated that weaker p53REs resided in open promoters, while stronger p53REs were located within enhancers and repressed chromatin. p53 occupancy was strongly correlated with similarity of the target DNA sequences to the p53RE consensus, but surprisingly, inversely correlated with pre-existing nucleosome accessibility (DHS) and evolutionary conservation at the p53RE. Occupancy by p53 of REs that overlapped transposable element (TE) repeats was significantly higher (p<10-7) and correlated with stronger p53RE sequences (p<10-110) relative to nonTE-associated p53REs, particularly for MLT1H, LTR10B, and Mer61 TEs. However, binding at these elements was generally not associated with transactivation of adjacent genes. Occupied p53REs located in L2-like TEs were unique in displaying highly negative PhyloP scores (predicted fast-evolving) and being associated with altered H3K4me3 and DHS levels. These results underscore the systematic interaction between chromatin status and p53RE context in the induced transactivation response. This p53 regulated response appears to have been tuned via evolutionary processes that may have led to repression and/or utilization of p53REs originating from primate-specific transposon elements.

Identifying Barriers and Practical Solutions to Conducting Site-Based Research in North America: Exploring Acute Heart Failure Trials As a Case Study.

Although the prognosis of ambulatory heart failure (HF) has improved dramatically there have been few advances in the management of acute HF (AHF). Despite regional differences in patient characteristics, background therapy, and event rates, AHF clinical trial enrollment has transitioned from North America and Western Europe to Eastern Europe, South America, and Asia-Pacific where regulatory burden and cost of conducting research may be less prohibitive. It is unclear if the results of clinical trials conducted outside of North America are generalizable to US patient populations. This article uses AHF as a paradigm and identifies barriers and practical solutions to successfully conducting site-based research in North America.

Dominant Splice Site Mutations in PIK3R1 Cause Hyper IgM Syndrome, Lymphadenopathy and Short Stature.

The purpose of this research was to use next generation sequencing to identify mutations in patients with primary immunodeficiency diseases whose pathogenic gene mutations had not been identified. Remarkably, four unrelated patients were found by next generation sequencing to have the same heterozygous mutation in an essential donor splice site of PIK3R1 (NM_181523.2:c.1425 + 1G > A) found in three prior reports. All four had the Hyper IgM syndrome, lymphadenopathy and short stature, and one also had SHORT syndrome. They were investigated with in vitro immune studies, RT-PCR, and immunoblotting studies of the mutation's effect on mTOR pathway signaling. All patients had very low percentages of memory B cells and class-switched memory B cells and reduced numbers of naïve CD4+ and CD8+ T cells. RT-PCR confirmed the presence of both an abnormal 273 base-pair (bp) size and a normal 399 bp size band in the patient and only the normal band was present in the parents. Following anti-CD40 stimulation, patient's EBV-B cells displayed higher levels of S6 phosphorylation (mTOR complex 1 dependent event), Akt phosphorylation at serine 473 (mTOR complex 2 dependent event), and Akt phosphorylation at threonine 308 (PI3K/PDK1 dependent event) than controls, suggesting elevated mTOR signaling downstream of CD40. These observations suggest that amino acids 435-474 in PIK3R1 are important for its stability and also its ability to restrain PI3K activity. Deletion of Exon 11 leads to constitutive activation of PI3K signaling. This is the first report of this mutation and immunologic abnormalities in SHORT syndrome.