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1.
J Community Health ; 2020 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737744

RESUMO

Little is known about Community Health Workers (CHWs) who work in non-clinical settings to provide sexual health support around HIV, viral hepatitis, and other sexually transmitted infections (STIs) to men who have sex with men (MSM) in Europe and neighbouring countries. This article describes for the first time, who CHWs are, and how they contribute to the continuum of services for HIV, viral hepatitis, and other STIs amongst MSM. The first European Community Health Worker Online Survey (ECHOES) developed in the framework of the EU-funded ESTICOM project ( www.esticom.eu ), was available in 16 languages (October 2017-January 2018). Amongst the 1035 persons aged 18 and older reporting CHW activities in the previous 12 months, 28.2% were women, 30.7% were volunteers, 59.2% were men self-defining as gay/homosexual, bisexual or queer ('peer CHWs'), and most CHWs worked/volunteered in private not-for-profit organisations (86.4%). CHWs involvement in the continuum of services for HIV, viral hepatitis and other STIs was as follows: primary prevention (88.6%), consultation and counselling (58.0%), testing provision (50.6%), linkage to care (49.8%), and treatment and support activities (51.3%). CHWs were also involved in cross-cutting activities such as developing interventions, advocacy, and engaging in research (46.3%). CHWs as a public health workforce contribute to all steps of the continuum of services for HIV, viral hepatitis, and other STIs amongst MSM in Europe. National governments should recognise and support CHWs better in order to make their activities more visible and sustainable, and increase their impact on the continuum of services.

2.
J Phys Chem Lett ; 11(16): 6892-6899, 2020 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-32787202

RESUMO

The realization of a train of molecule-gears working under the tip of a scanning tunneling microscope (STM) requires a stable anchor of each molecule to the metal surface. Such an anchor can be promoted by a radical state of the molecule induced by a dissociation reaction. Our results, rationalized by density functional theory calculations, reveal that such an open radical state at the core of star-shaped pentaphenylcyclopentadiene (PPCP) favors anchoring. Furthermore, to allow the transmission of motion by STM manipulation, the molecule-gears should be equipped with specific groups facilitating the tip-molecule interactions. In our case, a tert-butyl group positioned at one tooth end of the gear benefits both the tip-induced manipulation and the monitoring of rotation. With this optimized molecule, we achieve reproducible and stepwise rotations of the single gears and transmit rotations for up to three interlocked units.

3.
Phys Chem Chem Phys ; 22(27): 15208-15213, 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32427237

RESUMO

On a gold surface, supramolecules composed of 4-acetylbiphenyl molecules show structural directionality, reproducibility and robustness to external perturbations. We investigate the assembly of those molecules on the Au(111) surface and analyze how the observed supramolecular structures are the result of weak long-range dispersive forces stabilizing the 4-acetylbiphenyl molecules together. Metallic adatoms serve as stabilizing agents. Our analysis suggests new ways of creating complex molecular nano-objects that can eventually be used as devices or as seeds for extended hierarchical structures.

4.
J Phys Chem A ; 2020 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-32098473

RESUMO

Scanning probe microscopy and spectroscopy, and more recently, single-atom electron spin resonance, have allowed the direct observation of electron dynamics at the atomic limit. The interpretation of data is strongly dependent on model Hamiltonians. However, fitting effective spin Hamiltonians to experimental data lacks the ability to explore a vast number of potential systems of interest. By using plane-wave density functional theory as starting point, we build a multiplet Hamiltonian making use of maximally localized Wannier functions. The Hamiltonian contains spin-orbit and electron-electron interactions needed to obtain the relevant spin dynamics. The resulting reduced Hamiltonian is solved by exact diagonalization. We compare three prototypical cases of 3d transition metals Mn (total spin S = 5/2), Fe (S = 2), and Co (S = 3/2) on MgO with experimental data and find that our calculations can accurately predict the spin orientation and anisotropy of the magnetic adatom. Our method does not rely on experimental input and allows us to explore and predict the fundamental magnetic properties of adatoms on surfaces.

5.
Nano Lett ; 20(1): 384-388, 2020 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-31846337

RESUMO

The Kondo effect results from the interactions of the conduction electrons in a metal bulk with localized magnetic impurities. While adsorbed atop a metallic surface, the on-surface nanoscale version of this effect is observed when a single magnetic atom or a single magnetic molecule (SMM) is interacting with the conduction electrons. SMMs are commonly organometallic complexes incorporating transition-metal atoms in different oxidation states. We demonstrate how a single nonmagnetic neutral tetrabenzo[a,c,j,h]phenazine molecule can be on-surface-coordinated with exactly two aluminum metal atoms (between Al(I) and Al(II) oxidation state on the Au(111) surface) by low-temperature scanning tunneling microscope (LT-STM) single-atom manipulation. It results in a Kondo measurable localized molecular magnetic moment. This opens a new way to design SMM complexes without the need for heavy transition-metal atoms and complex ligands to stabilize the molecular coordination sphere.

6.
Nat Commun ; 10(1): 2211, 2019 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-31101815

RESUMO

The interaction among magnetic moments screened by conduction electrons drives quantum phase transitions between magnetically ordered and heavy-fermion ground states. Here, starting from isolated magnetic impurities in the Kondo regime, we investigate the formation of the finite size analogue of a heavy Fermi liquid. We build regularly-spaced chains of Co adatoms on a metallic surface by atomic manipulation. Scanning tunneling spectroscopy is used to obtain maps of the Kondo resonance intensity with sub-atomic resolution. For sufficiently small interatomic separation, the spatial distribution of Kondo screening does not coincide with the position of the adatoms. It also develops enhancements at both edges of the chains. Since we can rule out any other interaction between Kondo impurities, this is explained in terms of the indirect hybridization of the Kondo orbitals mediated by a coherent electron gas, the mechanism that causes the emergence of heavy quasiparticles in the thermodynamic limit.

7.
Nano Lett ; 19(5): 2750-2757, 2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-30933563

RESUMO

The planar heterocyclic molecules 1,6,7,12-tetraazaperylene on a Ag(111) metal substrate show different charging characteristics depending on their local environment: next to vacancies in self-assembled islands, molecules can be charged by local electric fields, whereas their charge state is fixed otherwise. This enables the activation of selected molecules inside islands by vacancy creation from scanning-probe-based manipulation. This concept allows for combining the precise mutual atomic-scale alignment of molecules by self-assembly, on one hand, and the implementation of specific functionality into otherwise homogeneous monolayers, on the other. Activated molecules in the direct neighborhood influence each other in their charging characteristics, suggesting their use as molecular quantum cellular automata. Surprisingly, only very few interacting molecules exhibit a rich spectroscopic signature, which offers the prospect of implementing complex functionality in such structures in the future.

8.
Nat Commun ; 10(1): 1573, 2019 04 05.
Artigo em Inglês | MEDLINE | ID: mdl-30952953

RESUMO

Miniaturization of electronic circuits into the single-atom level requires novel approaches to characterize transport properties. Due to its unrivaled precision, scanning probe microscopy is regarded as the method of choice for local characterization of atoms and single molecules supported on surfaces. Here we investigate electronic transport along the anisotropic germanium (001) surface with the use of two-probe scanning tunneling spectroscopy and first-principles transport calculations. We introduce a method for the determination of the transconductance in our two-probe experimental setup and demonstrate how it captures energy-resolved information about electronic transport through the unoccupied surface states. The sequential opening of two transport channels within the quasi-one-dimensional Ge dimer rows in the surface gives rise to two distinct resonances in the transconductance spectroscopic signal, consistent with phase-coherence lengths of up to 50 nm and anisotropic electron propagation. Our work paves the way for the electronic transport characterization of quantum circuits engineered on surfaces.

9.
Angew Chem Int Ed Engl ; 58(3): 821-824, 2019 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-30422385

RESUMO

Inert metal surfaces present more chances of hosting organic intact radicals than other substrates, but large amounts of delocalized electronic states favor charge transfer and thus spin quenching. Lowering the molecule-substrate interaction is a usual strategy to stabilize radicals on surfaces. In some works, thin insulating layers were introduced to provide a controllable degree of electronic decoupling. Recently, retinoid molecules adsorbed on gold have been manipulated with a scanning tunneling microscope (STM) to exhibit a localized spin, but calculations failed to find a radical derivative of the molecule on the surface. Now the formation of a neutral radical spatially localized in a tilted and lifted cyclic end of the molecule is presented. An allene moiety provokes a perpendicular tilt of the cyclic end relative to the rest of the conjugated chain, thus localizing the spin of the dehydrogenated allene in its lifted subpart. DFT calculations and STM manipulations give support to the proposed mechanism.

10.
Phys Rev Lett ; 121(22): 226402, 2018 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-30547609

RESUMO

Scanning tunneling spectroscopy measurements of Mn phthalocyanine (MnPc) molecules adsorbed on (sqrt[3]×sqrt[3]) surface alloys show single inelastic steps at exclusively positive or negative bias strongly depending on the tip position. This is in contrast to conventional molecular excitation thresholds, which are independent of the current direction and therefore always occur at both positive and negative bias. This polarity selectivity is found to coincide with the spatial distribution of occupied and empty orbitals. Because of the interaction with the substrate, charge transfer into the doubly degenerate d_{π} orbitals of MnPc takes place. The resulting Jahn-Teller effect lifts the degeneracy and leads to an isospin- or pseudospin-flip excitation, the inelastic analogue of an orbital Kondo resonance.

11.
Int J Drug Policy ; 62: 24-29, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30352331

RESUMO

BACKGROUND AND AIMS: Despite the availability of several drug consumption rooms (DCR) in different European countries few epidemiological studies have evaluated their benefits. A network of DCR for people who inject drugs (PWID) has existed in Catalonia since 2000. We aimed to study the impact of frequently attending DCR on injecting in public, infectious risk (disposal of used syringes in safe places, sharing needles and/or injecting equipment), accessing drug dependence services and non-fatal overdoses. METHODS: In 2014-2015, we performed the cross-sectional study REDAN in Catalonia's network of harm reduction centres (needle exchange programs, outreach programs, and DCR). A sample of current PWID were recruited. Self-reported data about risky and other behaviours and about access to care were collected through anonymous face-to-face structured interviews. Oral fluid samples were also collected to test for HIV and HCV antibodies. Multiple logistic regressions were used to assess the impact of frequently attending DCR on the different outcomes. RESULTS: Among the 730 PWID recruited, 510 reported attending DCR in the previous 6 months, of whom 21·2% were 'frequent' attenders. After multiple adjustment, frequent attenders had a 61% lower risk of injecting in public (AOR [95%CI]:0·39[0·18-0·85]) and sharing needles or other injecting equipment (0·39[0·18-0·85]) than 'medium' and 'low' attenders. They were six times more likely to place used syringes in a safe place (6·08[3·62-10·23]) and were twice as likely to access drug dependence services (2·56[1·44-4·55]). No significant effect was found for non-fatal overdoses, perhaps because of survival bias. CONCLUSION: The multiple benefits found strongly advocate for the maintenance of current DCR and the promotion of new DCR, in conjunction with other harm reduction strategies, in European countries where they are not yet available.


Assuntos
Usuários de Drogas/estatística & dados numéricos , Redução do Dano , Programas de Troca de Agulhas/estatística & dados numéricos , Adulto , Estudos Transversais , Overdose de Drogas/epidemiologia , Feminino , Infecções por HIV/epidemiologia , Hepatite C/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Uso Comum de Agulhas e Seringas/estatística & dados numéricos , Serviços Preventivos de Saúde , Assunção de Riscos , Espanha/epidemiologia , Transtornos Relacionados ao Uso de Substâncias/epidemiologia , Adulto Jovem
12.
Chem Commun (Camb) ; 54(73): 10260-10263, 2018 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-30152499

RESUMO

Achieving the Ag(001)-supported synthesis of heptacene from two related reactants reveals the effect of the presence of Br atoms on the reaction process. The properties of reactants, intermediates and end-products are further characterized by scanning tunneling microscopy and spectroscopy.

13.
Phys Rev Lett ; 120(16): 167001, 2018 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-29756947

RESUMO

We show that the magnetic ordering of coupled atomic dimers on a superconductor is revealed by their intragap spectral features. Chromium atoms on the superconductor ß-Bi_{2}Pd surface display Yu-Shiba-Rusinov bound states, detected as pairs of intragap excitations in tunneling spectra. By means of atomic manipulation with a scanning tunneling microscope's tip, we form Cr dimers with different arrangements and find that their intragap features appear either shifted or split with respect to single atoms. These spectral variations are associated with the magnetic coupling, ferromagnetic or antiferromagnetic, of the dimer, as confirmed by density functional theory simulations. The striking qualitative differences between the observed tunneling spectra prove that intragap Shiba states are extremely sensitive to the magnetic ordering on the atomic scale.

14.
Nano Lett ; 18(1): 88-93, 2018 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-29232947

RESUMO

The ability of molecules to maintain magnetic multistability in nanoscale-junctions will determine their role in downsizing spintronic devices. While spin-injection from ferromagnetic leads gives rise to magnetoresistance in metallic nanocontacts, nonmagnetic leads probing the magnetic states of the junction itself have been considered as an alternative. Extending this experimental approach to molecular junctions, which are sensitive to chemical parameters, we demonstrate that the electron affinity of a molecule decisively influences its spin transport. We use a scanning tunneling microscope to trap a meso-substituted iron porphyrin, putting the iron center in an environment that provides control of its charge and spin states. A large electron affinity of peripheral ligands is shown to enable switching of the molecular S = 1 ground state found at low electron density to S = 1/2 at high density, while lower affinity keeps the molecule inactive to spin-state transition. These results pave the way for spin control using chemical design and electrical means.

15.
Prog. obstet. ginecol. (Ed. impr.) ; 60(5): 474-479, sept.-oct. 2017. ilus
Artigo em Espanhol | IBECS | ID: ibc-167335

RESUMO

La identificación del sexo fetal forma parte de la ecografía de segundo trimestre. En ocasiones se presentan anomalías genitales que no permiten definirlo adecuadamente, lo que se conoce como genitales ambiguos. La importancia de los mismos se debe a su asociación con desórdenes del desarrollo sexual, patologías más complejas y graves. En la mayoría de casos el diagnóstico y el manejo es postnatal, estando bien establecido. El diagnóstico prenatal, en cambio, es poco frecuente, limitado y menos conocido. Presentamos el caso de una gestante de 20 años con el hallazgo de genitales ambiguos en semana 29 y posteriormente se diagnosticó de disgenesia gonadal mixta (AU)


Fetal sex identification is a well-established part of the second trimester ultrasound. Sometimes there are genital abnormalities that prevent proper identification, called ambiguous genitalia. Its importance is based on its association with development sex disorders, a far more severe and complex diseases. In most of the cases, diagnosis and management are postnatal and well systematized. Prenatal diagnosis, however, is less frequent and more limited. We present the case of a 20 year old pregnant with a finding of ambiguous genitalia at 29 week and a diagnosis of mixed gonadal dysgenesis (AU)


Assuntos
Humanos , Feminino , Gravidez , Adulto , Ultrassonografia Pré-Natal/métodos , Disgenesia Gonadal Mista/genética , Disgenesia Gonadal Mista , Transtornos do Desenvolvimento Sexual , Androstenodiona/deficiência , Diagnóstico Pré-Natal/métodos , Genitália/anormalidades , Genitália , Testosterona/administração & dosagem , Testosterona/deficiência , Diferenciação Sexual/efeitos da radiação , Processos de Determinação Sexual/efeitos da radiação
16.
Nano Lett ; 17(10): 6203-6209, 2017 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-28872317

RESUMO

The creation of molecule-like structures in which magnetic atoms interact controllably is full of potential for the study of complex or strongly correlated systems. Here, we create spin chains in which a strongly correlated Kondo state emerges from magnetic coupling of transition-metal atoms. We build chains up to ten atoms in length by placing Fe and Mn atoms on a Cu2N surface with a scanning tunneling microscope. The atoms couple antiferromagnetically via superexchange interaction through the nitrogen atom network of the surface. The emergent Kondo resonance is spatially distributed along the chain. Its strength can be controlled by mixing atoms of different transition metal elements and manipulating their spatial distribution. We show that the Kondo screening of the full chain by the electrons of the nonmagnetic substrate depends on the interatomic entanglement of the spins in the chain, demonstrating the prerequisites to build and probe spatially extended strongly correlated nanostructures.

17.
Nat Commun ; 8: 15175, 2017 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-28480879

RESUMO

A magnetic atom inside a superconductor locally distorts superconductivity. It scatters Cooper pairs as a potential with broken time-reversal symmetry, leading to localized bound states with subgap excitation energies, named Shiba states. Most conventional approaches regarding Shiba states treat magnetic impurities as point scatterers with isotropic exchange interaction. Here, we show that the number and the shape of Shiba states are correlated to the spin-polarized atomic orbitals of the impurity, hybridized with the superconductor. Using scanning tunnelling spectroscopy, we spatially map the five Shiba excitations found on subsurface chromium atoms in Pb(111), resolving their particle and hole components. While particle components resemble d orbitals of embedded Cr atoms, hole components differ strongly from them. Density functional theory simulations correlate the orbital shapes to the magnetic ground state of the atom, and identify scattering channels and interactions, all valuable tools for designing atomic-scale superconducting devices.

18.
Nano Lett ; 17(3): 1877-1882, 2017 03 08.
Artigo em Inglês | MEDLINE | ID: mdl-28199115

RESUMO

Inelastic electron tunneling spectroscopy (IETS) within the junction of a scanning tunneling microscope (STM) uses current-driven spin-flip excitations for an all-electrical characterization of the spin state of a single object. Usually decoupling layers between the single object, atom or molecule, and the supporting surface are needed to observe these excitations. Here we study the surface magnetism of a sandwich nickelocene molecule (Nc) adsorbed directly on Cu(100) by means of X-ray magnetic circular dichroism (XMCD) and density functional theory (DFT) calculations and show with IETS that it exhibits an exceptionally efficient spin-flip excitation. The molecule preserves its magnetic moment and magnetic anisotropy not only on Cu(100), but also in different metallic environments including the tip apex. By taking advantage of this robusteness, we are able to functionalize the microscope tip with a Nc, which can be employed as a portable source of inelastic excitations as exemplified by a double spin-flip excitation process.

19.
AIDS Care ; 29(8): 985-989, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28027661

RESUMO

The non-decreasing incidence of HIV among men who have sex with men (MSM) has motivated the emergence of Community Based Voluntary Counselling and Testing (CBVCT) services specifically addressed to MSM. The CBVCT services are characterized by facilitated access and linkage to care, a staff largely constituted by voluntary peers, and private not-for-profit structures outside the formal health system institutions. Encouraging results have been measured about their effectiveness, but these favourable results may have been obtained at high costs, questioning the opportunity to expand the experience. We performed an economic evaluation of HIV testing for MSM at CBVCT services, and compared them across six European cities. We collected retrospective data for six CBVCT services from six cities (Copenhagen, Paris, Lyon, Athens, Lisbon, and Ljubljana), for the year 2014, on the number of HIV tests and HIV reactive tests, and on all expenditures to perform the testing activities. The total costs of CBVCTs varied from 54,390€ per year (Ljubljana) to 245,803€ per year (Athens). The cost per HIV test varied from to 41€ (Athens) to 113€ (Ljubljana). The cost per HIV reactive test varied from 1966€ (Athens) to 9065€ (Ljubljana). Our results show that the benefits of CBVCT services are obtained at an acceptable cost, in comparison with the literature (values, mostly from the USA, range from 1600$ to 16,985$ per HIV reactive test in clinical and non-clinical settings). This result was transversal to several European cities, highlighting that there is a common CBVCT model, the cost of which is comparable regardless of the epidemiological context and prices. The CBVCT services represent an effective and "worth it" experience, to be continued and expanded in future public health strategies towards HIV.


Assuntos
Serviços de Saúde Comunitária/organização & administração , Análise Custo-Benefício , Infecções por HIV/economia , Homossexualidade Masculina , Programas de Rastreamento/economia , Programas de Rastreamento/estatística & dados numéricos , Adulto , Cidades , Pesquisa Participativa Baseada na Comunidade , Europa (Continente)/epidemiologia , Programas Governamentais , Infecções por HIV/diagnóstico , Infecções por HIV/epidemiologia , Infecções por HIV/prevenção & controle , Infecções por HIV/psicologia , Humanos , Masculino , Estudos Retrospectivos
20.
Rev. chil. pediatr ; 87(4): 261-267, ago. 2016. ilus, tab
Artigo em Espanhol | LILACS-Express | LILACS | ID: lil-796812

RESUMO

Introducción: El empleo de sulfato de magnesio para neuroprotección fetal es un tratamiento cada vez más frecuente. Objetivo: Estudiar la asociación entre sulfato de magnesio administrado a la gestante y la necesidad de reanimación neonatal. Pacientes y método: Estudio prospectivo de un grupo de prematuros menores de 32 semanas expuestos al sulfato de magnesio como neuroprotector y otro grupo retrospectivo inmediatamente anterior al inicio de este tratamiento. En ambos grupos se descartaron los casos que no habían recibido maduración pulmonar con corticoides. Se analizaron y compararon el porcentaje de reanimación y diferentes comorbilidades. Resultados: Se incluyó a 107 prematuros, 56 expuestos al sulfato de magnesio. El porcentaje de reanimación avanzada fue similar en ambos grupos. No se encontraron diferencias en mortalidad, ventilación mecánica invasiva, tiempo de la primera deposición y otras comorbilidades. Conclusiones: El sulfato de magnesio para neuroprotección no aumenta de forma significativa la necesidad de reanimación de los prematuros menores de 32 semanas.


Introduction: Magnesium sulphate administration is recommended for foetal neuroprotection in pregnant women at imminent risk of early preterm birth. Objective: To evaluate the relationship between intrapartum magnesium sulphate for foetal neuroprotection and delivery room resuscitation of preterm infants less 32 weeks. Patients and method: A prospective observational study was conducted on preterm infants less 32 weeks exposed to magnesium sulphate for neuroprotection, and a comparison made with another historic group immediately before starting this treatment. Cases in both groups that had not reached lung maturity with corticosteroids were rejected. The rates of resuscitation, morbidity and mortality for each of the groups were analysed and compared. Results: There was a total of 107 preterm, with 56 exposed to magnesium sulphate. Rate of advanced resuscitation were similar between the two groups. There were no other differences in mortality, invasive mechanical ventilation, time to first stool, and other comorbidities. Conclusions: Intrapartum magnesium sulphate for foetal neuroprotection was not associated with an increased need for intensive delivery room resuscitation and other morbidities in these cohorts of less than 32 weeks preterm infants.

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