Worlds of working poverty : Cross-national variation in the mechanisms that lead to poverty among workers

The objective of this paper is to distinguish between different types of working poverty, on the basis of the mechanisms that produce it. Whereas the poverty literature identifies a myriad of risk factors and of categories of disadvantaged workers, we focus on three immediate causes of working poverty, namely low wage rate, weak labour force attachment, and high needs, the latter mainly due to the presence of children (and sometimes to the increase in needs caused by a divorce). These three mechanisms are the channels through which macroeconomic, demographic and policy factors have a direct bearing on working households. The main assumption tested here is that welfare regimes strongly influence the relative weight of these three mechanisms in producing working poverty, and, hence, the composition of the working-poor population. Our figures confirm this hypothesis and show that low-wage employment is a key factor, but, by far, not the only one and that family policies broadly understood play a decisive role, as well as patterns of labour market participation and integration.

Nanoparticles in SiH4-Ar plasma: Modelling and comparison with experimental data

Experimental and theoretical investigations for growth of silicon nanoparticles (4 to 14 nm) in radio frequency discharge were carried out. Growth processes were performed with gas mixtures of SiH4 and Ar in a plasma chemical reactor at low pressure. A distinctive feature of presented kinetic model of generation and growth of nanoparticles (compared to our earlier model) is its ability to investigate small"critical" dimensions of clusters, determining the rate of particle production and taking into account the influence of SiH2 and Si2Hm dimer radicals. The experiments in the present study were extended to high pressure (≥20 Pa) and discharge power (≥40 W). Model calculations were compared to experimental measurements, investigating the dimension of silicon nanoparticles as a function of time, discharge power, gas mixture, total pressure, and gas flow.

Morphological and Magnetic Properties of Superparamagnetic Carbon-Coated Fe Nanoparticles Produced by Arc Discharge.

Spherical carbon coated iron particles of nanometric diameter in the 510 nm range have been produced by arc discharge at near-atmospheric pressure conditions (using 58·10 4 Pa of He). The particles exhibit a crystalline dense iron core with an average diameter 7.4 ± 2.0 nm surrounded by a sealed carbon shell, shown by transmission electron microscopy (TEM), selected-area diffrac- tion (SAED), energy-dispersive X-ray analysis (STEM-EDX) and electron energy loss spectroscopy (EELS). The SAED, EDX and EELS results indicate a lack of traces of core oxidized phases showing an efficient protection role of the carbon shell. The magnetic properties of the nanoparticles have been investigated in the 5300 K temperature range using a superconducting quantum interference device (SQUID). The results reveal a superparamagnetic behaviour with an average monodomain diameter of 7.6 nm of the nanoparticles. The zero field cooled and field cooled (ZFC-FC)magnetization curves show a blocking temperature (TB)at room temperature very suitable for biomedical applications (drug delivery, magnetic resonance imaging MRI, hyperthermia).

Learning form Nature to improve the heat generation of iron-oxide nanoparticles for magnetic hyperthermia applications.

The performance of magnetic nanoparticles is intimately entwined with their structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique way of engineering the magnetic response by modifying the strength of the dipolar interactions between particles. Here we report on an experimental and theoretical analysis of magnetic hyperthermia, a rapidly developing technique in medical research and oncology. Experimentally, we demonstrate that single-domain cubic iron oxide particles resembling bacterial magnetosomes have superior magnetic heating efficiency compared to spherical particles of similar sizes. Monte Carlo simulations at the atomic level corroborate the larger anisotropy of the cubic particles in comparison with the spherical ones, thus evidencing the beneficial role of surface anisotropy in the improved heating power. Moreover we establish a quantitative link between the particle assembling, the interactions and the heating properties. This knowledge opens new perspectives for improved hyperthermia, an alternative to conventional cancer therapies.

Fate of Hydrophilic Nanoparticles in Biological Environments

The nanoparticles developed are based on chitosan, a biocompatible and biodegradable polysaccharide. The chitosan nanoparticles are formed in an entirely water-based process by electrostatic interactions with other biocompatible molecules. As a prerequisite to understand the fate of such nanoparticles in cells, comprehensive characterization and stability studies serve to identify quantitatively the impact of the raw material characteristics and preparation conditions on the nanoparticle characteristics. Methods included H-1 NMR spectroscopy, dilution viscometry, particle size analysis and electron microscopy. Cytotoxicity and cell uptake experiments on RAW 264.7 murine macrophages and p23 murine endothelial cells were performed to investigate the correlation with nanoparticle characteristics and effect of surface decoration with alginate. Cytotoxicity was assessed by the MTT survival test; cell uptake was monitored by fluorescent microscopy using labeled polymers.

Detecting the oxidative reactivity of nanoparticles: a new protocol for reducing artifacts

Understanding the oxidative reactivity of nanoparticles (NPs; <100 nm) could substantially contribute to explaining their toxicity. We attempted to refine the use of 2′7-dichlorodihydrofluorescein (DCFH) to characterize NP generation of reactive oxygen species (ROS). Several fluorescent probes have been applied to testing oxidative reactivity, but despite DCFH being one of the most popular for the detection of ROS, when it has been applied to NPs there have been an unexplainably wide variability in results. Without a uniform methodology, validating even robust results is impossible. This study, therefore, identified sources of conflicting results and investigated ways of reducing occurrence of artificial results. Existing techniques were tested and combined (using their most desirable features) to form a more reliable method for the measurement of NP reactivity in aqueous dispersions. We also investigated suitable sample ranges necessary to determine generation of ROS. Specifically, ultrafiltration and time-resolved scan absorbance spectra were used to study possible optical interference when using high sample concentrations. Robust results were achieved at a 5 µM DCFH working solution with 0.5 unit/mL horseradish peroxidase (HRP) dissolved in ethanol. Sonication in DCFH-HRP working solution provided more stable data with a relatively clean background. Optimal particle concentration depends on the type of NP and in general was in the µg/mL range. Major reasons for previously reported conflicting results due to interference were different experimental approaches and NP sample concentrations. The protocol presented here could form the basis of a standardized method for applying DCFH to detect generation of ROS by NPs.

Nanoparticles for fingermark detection: an insight into the reaction mechanism

This publication presents one of the first uses of silicon oxide nanoparticles to detect fingermarks. The study is not confined to showing successful detection of fingermarks, but is focused on understanding the mechanisms involved in the fingermark detection process. To gain such an understanding, various chemical groups are grafted onto the nanoparticle surface, and parameters such as the pH of the solutions or zeta potential are varied to study their influence on the detection. An electrostatic interaction has been the generally accepted hypothesis of interaction between nanoparticles and fingermarks, but the results of this research challenge that hypothesis, showing that the interaction is chemically driven. Carboxyl groups grafted onto the nanoparticle surfaces react with amine groups of the fingermark secretion. This formation of amide linkage between carboxyl and amine groups has further been favoured by catalyzing the reaction with a compound of diimide type. The research strategy adopted here ought to be applicable to all detection techniques using nanoparticles. For most of them the nature of the interaction remains poorly understood.

An evaluation of the inorganic and organic geochemistry of the San Vicente Mississippi Valley-type zinc-lead district, central Peru: Implications for ore fluid composition, mixing processes, and sulfate reduction

Mississippi Tialley-type zinc-lead deposits and ore occurrences in the San Vicente belt are hosted in dolostones of the eastern Upper Triassic to Lower Jurassic Pucara basin, central Peru. Combined inorganic and organic geochemical data from 22 sites, including the main San Vicente deposit, minor ore occurrences, and barren localities, provide better understanding of fluid pathways and composition, ore precipitation mechanisms, Eh-pH changes during mineralization, and relationships between organic matter and ore formation. Ore-stage dark replacement dolomite and white sparry dolomite are Fe and rare earth element (REE) depleted, and Mn enriched, compared to the host dolomite. In the main deposit, they display significant negative Ce and probably Eu anomalies. Mixing of an incoming hot, slightly oxidizing, acidic brine (H2CO3 being the dominant dissolved carbon species), probably poor in REE and Fe, with local intraformational, alkaline, reducing waters explains the overall carbon and oxygen isotope variation and the distributions of REE and other trace elements in the different hydrothermal carbonate generations. The incoming ore fluid flowed through major aquifers, probably basal basin detrital units, with limited interaction with the carbonate host rocks. The hydrothermal carbonates show a strong regional chemical homogeneity, indicating access of the ore fluids by interconnected channelways near the ore occurrences. Negative Ce anomalies in the main deposit, that are absent at the district scale, indicate local ore-fluid chemical differences. Oxidation of both migrated and indigenous hydrocarbons by the incoming fluid provided the local reducing conditions necessary for sulfate reduction to H2S, pyrobitumen precipitation, and reduction of Eu3+ to Eu2+. Fe-Mn covariations, combined with the REE contents of the hydrothermal carbonates, are consistent with the mineralizing system shifting from reducing/rock-dominated to oxidizing/fluid-dominated conditions following ore deposition. Sulfate and sulfide sulfur isotopes support sulfide origin from evaporite-derived sulfate by thermochemical organic reduction; further evidence includes the presence of C-13-depleted calcite cements (similar to-12 parts per thousand delta(13)C) as sulfate pseudomorphs, elemental sulfur, altered organic matter in the host dolomite, and isotopically heavier, late, solid bitumen. Significant alteration of the indigenous and extrinsic hydrocarbons, with absent bacterial membrane biomarkers (hopanes) is observed. The light delta(34)S of sulfides from small mines and occurrences compared to the main deposit reflect a local contribution of isotopically light sulfur, evidence of local differences in the ore-fluid chemistry.

Surface-functionalized ultrasmall superparamagnetic nanoparticles as magnetic delivery vectors for camptothecin.

Drug-nanoparticle conjugates: The anticancer drug camptothecin (CPT) was covalently linked at the surface of ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) via a linker, allowing drug release by cellular esterases. Nanoparticles were hierarchically built to achieve magnetically-enhanced drug delivery to human cancer cells and antiproliferative activity.The linking of therapeutic drugs to ultrasmall superparamagnetic iron oxide nanoparticles (USPIOs) allowing intracellular release of the active drug via cell-specific mechanisms would achieve tumor-selective magnetically-enhanced drug delivery. To validate this concept, we covalently attached the anticancer drug camptothecin (CPT) to biocompatible USPIOs (iron oxide core, 9-10 nm; hydrodynamic diameter, 52 nm) coated with polyvinylalcohol/polyvinylamine (PVA/aminoPVA). A bifunctional, end-differentiated dicarboxylic acid linker allowed the attachment of CPT to the aminoPVA as a biologically labile ester substrate for cellular esterases at one end, and as an amide at the other end. These CPT-USPIO conjugates exhibited antiproliferative activity in vitro against human melanoma cells. The intracellular localization of CPT-USPIOs was confirmed by transmission electron microscopy (iron oxide core), suggesting localization in lipid vesicles, and by fluorescence microscopy (CPT). An external static magnetic field applied during exposure increased melanoma cell uptake of the CPT-USPIOs.

Si3N4 single-crystal nanowires grown from silicon micro- and nanoparticles near the threshold of passive oxidation

A simple and most promising oxide-assisted catalyst-free method is used to prepare silicon nitride nanowires that give rise to high yield in a short time. After a brief analysis of the state of the art, we reveal the crucial role played by the oxygen partial pressure: when oxygen partial pressure is slightly below the threshold of passive oxidation, a high yield inhibiting the formation of any silica layer covering the nanowires occurs and thanks to the synthesis temperature one can control nanowire dimensions

Enhancement of oxidation rate of a-Si nanoparticles during dehydrogenation

Oxidation of amorphous silicon (a-Si) nanoparticles grown by plasma-enhanced chemical vapor deposition were investigated. Their hydrogen content has a great influence on the oxidation rate at low temperature. When the mass gain is recorded during a heating ramp in dry air, an oxidation process at low temperature is identified with an onset around 250°C. This temperature onset is similar to that of hydrogen desorption. It is shown that the oxygen uptake during this process almost equals the number of hydrogen atoms present in the nanoparticles. To explain this correlation, we propose that oxidation at low temperature is triggered by the process of hydrogen desorption

Does less frequent routine monitoring of patients on a stable, fully suppressed cART regimen lead to an increased risk of treatment failure?

OBJECTIVE: To investigate whether HIV-infected patients on a stable and fully suppressive combination antiretroviral therapy (cART) regimen could safely be monitored less often than the current recommendations of every 3 months. DESIGN: Two thousand two hundred and forty patients from the EuroSIDA study who maintained a stable and fully suppressed cART regimen for 1 year were included in the analysis. METHODS: Risk of treatment failure, defined by viral rebound, fall in CD4 cell count, development of new AIDS-defining illness, serious opportunistic infection or death, in the 12 months following a year of a stable and fully suppressed regimen was assessed. RESULTS: One hundred thirty-one (6%) patients experienced treatment failure in the 12 months following a year of stable therapy, viral rebound occurred in 99 (4.6%) patients. After 3, 6 and 12 months, patients had a 0.3% [95% confidence interval (CI) 0.1-0.5], 2.2% (95% CI 1.6-2.8) and 6.0% (95% CI 5.0-7.0) risk of treatment failure, respectively. Patients who spent more than 80% of their time on cART with fully suppressed viraemia prior to baseline had a 38% reduced risk of treatment failure, hazard ratio 0.62 (95% CI 0.42-0.90, P = 0.01). CONCLUSION: Patients who have responded well to cART and are on a well tolerated and durably fully suppressive cART regimen have a low chance of experiencing treatment failure in the next 3-6 months. Therefore, in this subgroup of otherwise healthy patients, it maybe reasonable to extend visit intervals to 6 months, with cost and time savings to both the treating clinics and the patients.