Tuning the Kondo effect in thin Au films by depositing a thin layer of Au on molecular spin-dopants

We report on the tuning of the Kondo effect in thin Au films containing a monolayer of cobalt(II) terpyridine complexes by altering the ligand structure around the Co(2+) ions by depositing a thin Au capping layer on top of the monolayer on Au by magnetron sputtering (more energetic) and e-beam evaporation (softer). We show that the Kondo effect is slightly enhanced with respect to that of the uncapped film when the cap is deposited by evaporation, and significantly enhanced when magnetron sputtering is used. The Kondo temperature (TK) increases from 3 to 4.2/6.2 K for the evaporated/sputtered caps. X-ray absorption spectroscopy and surface-enhanced Raman spectroscopy investigation showed that the organic ligands remain intact upon Au e-beam evaporation; however, sputtering inflicts significant change in the Co(2+) electronic environment. The location of the monolayer-on the surface or embedded in the film-has a small effect. However, the damage of Co-N bonds induced by sputtering has a drastic effect on the increase of the impurity-electron interaction. This opens up the way for tuning of the magnetic impurity states, e.g. spin quantum number, binding energy with respect to the host Fermi energy, and overlap via the ligand structure around the ions.

Infrared spectroscopy and the ferromagnetic transition in Gd

The low energy electronic structure of Gd has been investigated experimentally by infrared reflectance spectroscopy, and theoretically from first principles, using the fully relativistic Dirac linear-muffin-tin-orbital (LMTO) method in the local spin density approximation (LSDA) as well as within the LSDA + U approach. The reflectance of a Gd single crystal was measured with the electric field in the plane perpendicular to the c-axis for temperatures between 50 K and slightly above the Curie temperature (293 K) in the frequency range between 100 and 12 000 cm(-1) (0.013-1.5 eV). As Gd enters the ferromagnetic state, the dissipative part of the optical conductivity exhibits interesting spectral weight transfers over the whole spectral range measured. It is shown that the ab initio calculations reproduce well the experimental spectra for the ferromagnetic state and allow one to explain the microscopic origin of the optical response of Gd in terms of interband transitions.

Willingness to pay for emergency referral transport in a developing setting: a geographically randomized study

OBJECTIVES

The objective was to identify the correlates of willingness to pay for ambulance transports from a rural city to a regional hospital in Guatemala.

METHODS

An innovative methodology that utilizes a novel randomization technique and satellite imagery was used to select a sample of homes in Santiago Atitlán, Guatemala. The respondents were surveyed at these homes about their willingness to pay for ambulance transport to a regional hospital. A price ladder was used to elicit respondents' willingness to pay for ambulance transport, depending on the level of severity of three types of emergencies: life-threatening emergencies, disability-causing emergencies, and simple emergencies. Simple and multiple linear regression modeling was used to identify the social and economic correlates of respondents' willingness to pay for ambulance transport and to predict demand for ambulance transport at a variety of price levels. Beta coefficients (β) expressed as percentages with 95% confidence intervals (CIs) were estimated.

RESULTS

The authors surveyed 134 respondents (response rate=3.3%). In the multivariable regression models, three variables correlated with willingness to pay: household income, location of residence (rural district vs. urban district), and respondents' education levels. Correlates for ambulance transport in life-threatening emergencies included greater household daily income (β=1.32%, 95% CI=0.63% to 2.56%), rural location of residence (β=-37.3%, 95% CI=-51.1% to -137.5%), and higher educational levels (β=4.41%, 95% CI=1.00% to 6.36%). Correlates of willingness to pay in disability-causing emergencies included greater household daily income (β=1.59%, 95% CI=0.81% to 3.19%) and rural location of residence (β=-19.4%, 95% CI=-35.7% to -89.4%). Correlates of willingness to pay in simple emergencies included rural location of residence (β=59.4%, 95% CI=37.9% to 133.7%) and higher educational levels (β=7.96%, 95% CI=1.96% to 11.8%). At all price levels, more individuals were willing to pay for transport for a life-threatening emergency than a disability-causing emergency. Respondents' willingness to pay was more responsive to price changes for transport during disability-causing emergencies than for transport during life-threatening emergencies.

CONCLUSIONS

The primary correlates of willingness to pay for ambulance transport in Santiago Atitlán, Guatemala, are household income, location of residence (rural district vs. urban district), and respondents' education levels. Furthermore, severity of emergency significantly appears to influence how much individuals are willing to pay for ambulance transport. Willingness-to-pay information may help public health planners in resource-poor settings develop price scales for health services and achieve economically efficient allocations of subsidies for referral ambulance transport.

Tunable doping of a metal with molecular spins

The mutual interaction of localized magnetic moments and their interplay with itinerant conduction electrons in a solid are central to many phenomena in condensed-matter physics, including magnetic ordering and related many-body phenomena such as the Kondo effect, the Ruderman-Kittel-Kasuya-Yoshida interaction and carrier-induced ferromagnetism in diluted magnetic semiconductors. The strength and relative importance of these spin phenomena are determined by the magnitude and sign of the exchange interaction between the localized magnetic moments and also by the mean distance between them. Detailed studies of such systems require the ability to tune the mean distance between the localized magnetic moments, which is equivalent to being able to control the concentration of magnetic impurities in the host material. Here, we present a method for doping a gold film with localized magnetic moments that involves depositing a monolayer of a metal terpyridine complex onto the film. The metal ions in the complexes can be cobalt or zinc, and the concentration of magnetic impurities in the gold film can be controlled by varying the relative amounts of cobalt complexes (which carry a spin) and zinc complexes (which have zero spin). Kondo and weak localization measurements demonstrate that the magnetic impurity concentration can be systematically varied up to ∼800 ppm without any sign of inter-impurity interaction. Moreover, we find no evidence for the unwanted clustering that is often produced when using alternative methods.

Striatal dopamine synthesis capacity in twins discordant for schizophrenia

BACKGROUND

Elevated striatal dopamine synthesis capacity is thought to be fundamental to the pathophysiology of schizophrenia and has also been reported in people at risk of psychosis. It is therefore unclear if striatal hyperdopaminergia is a vulnerability marker for schizophrenia, or a state feature related to the psychosis itself. Relatives of patients with schizophrenia are themselves at increased risk of developing the condition. In this study we examined striatal dopamine synthesis capacity in both members of twin pairs discordant for schizophrenia.

METHOD

In vivo striatal dopamine synthesis capacity was examined using fluorine-18-l-dihydroxyphenylalanine (18F-DOPA) positron emission tomography (PET) scans in seven twin pairs discordant for schizophrenia and in a control sample of 10 healthy control twin pairs.

RESULTS

Striatal 18F-DOPA uptake was not elevated in the unaffected co-twins of patients with schizophrenia (p=0.65) or indeed in the twins with schizophrenia (p=0.89) compared to the control group. Levels of psychotic symptoms were low in the patients with schizophrenia who were in general stable [mean (s.d.) Positive and Negative Syndrome Scale (PANSS) total=56.8 (25.5)] whereas the unaffected co-twins were largely asymptomatic.

CONCLUSIONS

Striatal dopamine synthesis capacity is not elevated in symptom-free individuals at genetic risk of schizophrenia, or in well-treated stable patients with chronic schizophrenia. These findings suggest that striatal hyperdopaminergia is not a vulnerability marker for schizophrenia.

Multi-Scale hierarchical generation of PET parametric maps: application and testing on a [11C]DPN study

We propose a general approach to generate parametric maps. It consists in a multi-stage hierarchical scheme where, starting from the kinetic analysis of the whole brain, we then cascade the kinetic information to anatomical systems that are akin in terms of receptor densities, and then down to the voxel level. A-priori classes of voxels are generated either by anatomical atlas segmentation or by functional segmentation using unsupervised clustering. Kinetic properties are transmitted to the voxels in each class using maximum a posteriori (MAP) estimation method. We validate the novel method on a [11C]diprenorphine (DPN) test-retest data-set that represents a challenge to estimation given [11C]DPN's slow equilibration in tissue. The estimated parametric maps of volume of distribution (VT) reflect the opioid receptor distributions known from previous [11C]DPN studies. When priors are derived from the anatomical atlas, there is an excellent agreement and strong correlation among voxel MAP and ROI results and excellent test-retest reliability for all subjects but one. Voxel level results did not change when priors were defined through unsupervised clustering. This new method is fast (i.e. 15 min per subject) and applied to [11C]DPN data achieves accurate quantification of VT as well as high quality VT images. Moreover, the way the priors are defined (i.e. using an anatomical atlas or unsupervised clustering) does not affect the estimates.

Adenosine 2A receptor availability in dyskinetic and nondyskinetic patients with Parkinson disease

OBJECTIVE

To investigate striatal adenosine A2A receptor availability in patients with Parkinson disease (PD) with and without levodopa-induced dyskinesias (LIDs). While providing effective relief from the motor symptoms of PD, chronic levodopa use is associated with development of LIDs. A2A receptors are expressed on the bodies of indirect pathway medium spiny striatal neurons and on dopamine terminals and play a role in modulating dopamine transmission. A2A antagonists have antiparkinsonian activity by boosting levodopa efficacy. We aimed to study A2A receptor availability in patients with PD with and without LIDs using PET and [¹¹C]SCH442416, an A2A antagonist.

METHODS

Six patients with PD with and 6 without LIDs were studied withdrawn 12 hours from medication. Their PET findings were compared with 6 age-matched healthy controls. Using spectral analysis, [¹¹C]SCH442416 regional volumes of distribution (V(T)) were computed for the caudate, putamen, and thalamus and binding potentials (BP(ND)) reflecting the ratio of specific:nonspecific uptake were compared between groups.

RESULTS

A2A binding in the caudate and putamen of subjects with PD with LIDs was far higher (p = 0.026 and p = 0.036, respectively) than that of subjects with PD without LIDs, which lay within the control range. Thalamic A2A availability was similar for all 3 groups.

CONCLUSION

Patients with PD with LIDs show increased A2A receptor availability in the striatum. This finding is compatible with altered adenosine transmission playing a role in LIDs and provides a rationale for a trial of A2A receptor agents in the treatment of these motor complications.

Effect of additives on fiber yield improvement for kraft pulping of kadam (Anthocephalus chinensis)

Projected decline in future wood resources has prompted researchers to try various additives in existing pulping processes for fiber yield improvement. Many studies have been conducted in the past aimed at improving kraft pulp yield with the use of additives in the cooking liquor. In this study, the effects of anthraquinone (AQ) and 2-methylanthraquinone (MAQ) on the pulp yield of kadam (Anthocephalus chinensis) were investigated. Three different active alkali doses (14%, 16% and 19% as NaOH) along with 0.1% of AQ or MAQ on chips were used to obtain various levels of delignification of the hardwood. Addition of AQ or MAQ to kraft pulping, increased fiber yield (0.5-2.7% on chips) and improved delignification selectivity (lignin vs. carbohydrate removal). Increases in pulp yield due to AQ or MAQ were more significant at lower doses of active alkalis. The viscosities and the physical strength properties of the pulps with kappa numbers 16-19 were comparable to kraft although there was a minor decrease in tensile strength for the kraft/MAQ pulp.

Electron-phonon coupling and spin fluctuations in 3d and 4d transition metals: implications for superconductivity and its pressure dependence

We have calculated the electron-phonon coupling for the complete 4d series and the nonmagnetic 3d transition metals using the linear response method and the linear muffin-tin orbitals' basis. A comparison of the linear response results and those obtained via the rigid muffin-tin approximation is provided. Based on the calculated values of the electron-phonon coupling constants, band density of states and the measured values of the electronic specific heat constants, we estimate the spin-fluctuation effects, i.e. the electron-spin-fluctuation (electron-paramagnon) coupling constants in these systems. For the sake of comparison, several other metals, Cu, Zn, Ag, Cd, Al and Pb, are also studied. Alternative estimates of the electron-paramagnon coupling constants are obtained from the values of the Stoner parameters and the band densities of states at the Fermi level. Implications of these results on the superconductivity and its pressure dependence as well as the alloying effects of superconductivity in these systems are discussed. It is pointed out that spin fluctuations play an important role in the validity of the Matthias rule that in metallic systems the optimum conditions for (electron-phonon) superconductivity occur for 5 and 7 valence electrons/atom.

Positive and negative aspects of soda/anthraquinone pulping of hardwoods

The positive aspects of the non-sulfur soda/anthraquinone (SAQ) process are mostly tied to improved energy efficiency while lower pulp brightness after bleaching is its most significant drawback. A credible method that quantifies bleachability as well as an approach that solves the problem for SAQ pulps from hardwoods will be described. A straight line correlation (R2=0.904) was obtained between O2 kappa number and final light absorption coefficient (LAC) value after standardized OD0EpD1 bleaching of nine hardwood kraft pulps from three laboratories and one pulp mill. The bleachability of pulps from four different soda processes catalyzed by anthraquinone (AQ) and 2-methylanthraquinone (MAQ) was compared to that of conventional kraft pulps by comparing O2 kappa number decrease and final LAC values. It was observed that a mild hot water pre-hydrolysis improved the bleachability of SAQ pulps to a level equal to that of kraft.

Momentum-resolved electron-phonon interaction in lead determined by neutron resonance spin-echo spectroscopy

Neutron resonance spin-echo spectroscopy was used to monitor the temperature evolution of the linewidths of transverse acoustic phonons in lead across the superconducting transition temperature over an extended range of the Brillouin zone. For phonons with energies below the superconducting energy gap, a linewidth reduction of maximum amplitude was observed below . The electron-phonon contribution to the phonon lifetime extracted from these data is in satisfactory overall agreement with ab initio lattice-dynamical calculations, but significant deviations are found.

Flurbiprofen, a unique non-steroidal anti-inflammatory drug with antimicrobial activity against Trichophyton, Microsporum and Epidermophyton species

AIMS

The objective of this study was to determine the antifungal activity of flurbiprofen against dermatophytes like Trichophyton, Microsporum and Epidermophyton species.

METHODS AND RESULTS

Susceptibility tests were performed against dermatophytes like Trichophyton, Microsporum and Epidermophyton species by the microbroth dilution method. Among the dermatophytes tested, Trichophyton, Microsporum and Epidermophyton species are remarkably susceptible to this compound (MIC(50): 8-16 microg ml(-1)). A yeast pathogen, Candida albicans, and a bacterium, Staphylococcus aureus, are also susceptible to flurbiprofen.

CONCLUSIONS

Flurbiprofen is a non-steroidal anti-inflammatory compound with strong antifungal activity, which is not found in two well known and medically used antifungal organic acids like benzoic and salicylic acids.

SIGNIFICANCE AND IMPACT OF THE STUDY

The present action of flurbiprofen on microbes indicates its future prospects as an antimicrobial agent against dermatophytes and yeast pathogens. However, in view of the anti-inflammatory property of flurbiprofen, its antifungal action may provide an additional advantage for use as a skin ointment.

Inhibition of early DNA-damage and chromosomal aberrations by Trianthema portulacastruml. In carbon tetrachloride-induced mouse liver damage

The underlying molecular mechanisms of the antihepatotoxic activity of Trianthema portulacastrum by monitoring its effect on mouse liver DNA-chain break, sugar-base damage and chromosomal aberrations, during chronic or acute treatment with carbon tetrachloride (CCl(4)) have been studied. Daily oral feeding with the ethanolic extract (150 mg/kg basal diet, per os) was given 2 weeks before CCl(4)treatment and continued until the end of the experiment (13 weeks). T. portulacastrum extract offer unique protection (P< 0.05-0. 001) against the induction of liver-specific structural-type chromosomal anomalies 15, 30 or 45 days after the last CCl(4)insult, compared to control mice. This was further evidenced by extract-mediated protection (15 days prior feeding following a single necrogenic dose of CCl(4)) of the generation of DNA chain-break and Fe-sugar-base damage assays. The observed hepatoprotective mechanism could be due to its ability to counteract oxidative injury to DNA in the liver of mouse.

A histidine thiol 100 kDa, tetrameric acid phosphatase from lentil, Lens esculenta, seeds with the characteristics of protein tyrosine phosphatases

A non-specific acid phosphatase (APase) hydrolysing L-tyrosine-O-phosphate and 3'-AMP was purified to electrophoretic homogeneity from mature lentil seeds with apparent native molecular mass of 100 kDa and subunit molecular mass of 24 kDa. These activities appear to reside on the same protein which shows a single band in native and SDS-PAGE. The pH optimum is 5.5, while the K(m) (mM) and V(max) (micromoles/min/mg protein) for p-nitrophenyl phosphate (pNPP) are 0.7 and 9.2 and for L-tyrosine-O-phosphate 1.4 and 10.1, respectively, at 30 degrees C and for 3'-AMP, 2 and 4.4 at 37 degrees C. The protein also hydrolyses other phosphomonoesters to a lesser extent. L-Tyrosine-O-phosphate, 3'-AMP and pNPP hydrolysis is potently inhibited by micromolar orthovanadate and also to nearly the same extent by sodium fluoride, potassium tartrate and metal ions. Histidine and cysteine are likely to be involved in the catalysis. Thermal inactivation studies indicate that the active site conformations for pNPP and 3'-AMP hydrolytic activities are different. The enzyme shows the characteristics of the animal protein tyrosine phosphatase.

Induction of a germination specific, low molecular weight, acid phosphatase isozyme with specific phosphotyrosine phosphatase activity in lentil (Lens esculenta) seeds

A germination specific isozyme of acid phosphatase (EC 3.1.3.2) hydrolysing O-phospho-L-Tyrosine, pH optima 5.5 is induced in lentil seeds. When seeds at 0 h, 24 h and 36 h of germination are electrophorezed, native PAGE on specific enzyme staining shows several constitutive isozymes of acid phosphatases. At 48 h, an isozyme is induced which gradually decreases and then disappears at 108 h of germination. The short lived, induced isozyme is present in the embryo and seed-coat but not in the plumule and the radical. Induction of this isozyme is inhibited by cycloheximide and actinomycin-D and increased by plant growth regulators such as heteroauxin and gibbrellic acid treatment during germination. The induced isozyme is a single 30 kD polypeptide, with subunit molecular mass of 25 kD, shows activity for O-phospho-L-Tyrosine. It is strongly inhibited by vanadate (microM), molybdate, tungustate as also by iodoacetate, p-chloromercuribenzoate and diethylpyrocarbonate. This study shows for the first time that the germination induced low molecular weight Acid phosphatase is a Tyrosine phosphatase super family class IV enzyme, having a role in cellular differentiation and development during seed germination.

Studies on the aerobic photooxidation of cysteine using riboflavin as a sensitizer: evidence for the photogeneration of a superoxide anion and hydrogen peroxide

The riboflavin sensitized oxidation of cysteine under an aerobic condition was investigated. The effects of various scavengers, such as superoxide dismutase, catalase, mannitol, sodium azide and potassium ferrocyanide (an electron donor), on the photooxidation were determined. A reaction mechanism involving the superoxide anion is proposed for the photooxidation of cysteine to cysteic acid.

Isolation and properties of an ATP transporter from a strain of Aspergillus niger

A purified ATP transporter from Aspergillus niger did not show release or uptake for any of the nucleotides (ADP or UTP) except ATP. The release and uptake did not result from non-specific binding, but appeared to be concentration-dependent processes. ATP was shown by a double-isotopic technique to be transported across membrane vesicles without degradation. The ATP-transport protein was purified to near homogeneity from the membrane vesicles of a strain of A. niger and its apparent Mr was approximately 60000. The purified protein showed the properties of a membrane-bound protein in that the carrier protein was shown, during the liposome-preparative process, to translocate from the aqueous phase into the lipid bilayer of the liposome, unlike the cytosolic protein glucose-6-phosphate dehydrogenase, which remained confined to the aqueous compartment. Mycobacillin, a lipid-reactive antibiotic, was bound to the transport protein at a site other than the ATP-binding site, leading to its enhanced release or uptake, which was very feeble in absence of the antibiotic.

Antiinflammatory activity of tissue plasminogen activator in the carrageenan rat footpad model

Exogenous plasminogen activators (PAs), such as streptokinase (SK) and tissue plasminogen activator (tPA), have been shown to significantly improve the mortality of patients with acute myocardial infarction. However, reperfusion of the myocardium is associated with neutrophil activation and infiltration into the infarct region. Plasminogen activators influence neutrophil function in vitro, but no data exists regarding the effect of exogenous PAs on inflammation in vivo. Therefore, we evaluated the effect of PAs on inflammation using the carrageenan-induced rat footpad inflammation model. The magnitude of carrageenan-induced inflammation was determined by water-displacement and neutrophil infiltration, following administration of either tPA or SK to Sprague-Dawley rats. tPA (12 mg/kg) inhibited carrageenan-induced inflammation (p < .01). In contrast, administration of SK (40,000 U/kg) enhanced inflammation. These results suggest that exogenous PAs influence the inflammatory process but specific PAs differ in their actions. Ultimately, these differences may influence the efficacy of these agents in the management of acute myocardial infarction and lead to further evaluation of tPA in other inflammatory diseases such as acute respiratory distress syndrome (ARDS) and rheumatoid arthritis (RA), in which neutrophil-mediated injury is likely.

Association of Melkersson-Rosenthal syndrome with rosacea

A rare case of Melkersson-Rosenthal syndrome with all the cardinal signs of the triad, including facial swelling, facial nerve palsy and glossitis, is described. The additional feature of this case was an association with rosacea.