Ultrafast dynamics of delocalized and localized electrons in carbon nanotubes

We report on the dynamics of the dielectric function of single-wall carbon nanotubes in the 10-30 THz frequency range after ultrafast laser excitation. The absence of a distinct free-carrier response is attributed to the photogeneration of strongly bound excitons in the tubes with large energy gaps. We find a feature of enhanced transmission caused by the blocking of optical transitions in small-gap tubes. The rapid decay of a featureless background with pronounced dichroism is associated with the increased absorption of spatially localized charge carriers before thermalization is completed.

House dust mites (Der p 1, Der f 1), cat (Fel d 1) and cockroach (Bla g 2) allergens in indoor work-places (offices and archives)

BACKGROUND

Exposure to indoor allergens has already been shown to occur in many public places, including workplaces, in several countries. Aim of this study was to measure the levels of house dust mites, cat and cockroach allergens in indoor workplaces (offices and archives) in Italy and to evaluate the possible relationships between allergen levels and building characteristics, type of ventilation, indoor relative humidity and temperature.

METHODS

Der f 1 and Der p 1, Fel d 1, Bla g 2 were measured by ELISA in dust samples collected from floors or upholstered seats of 160 workplaces.

RESULTS

Detectable Der p 1 levels were found in 86 (54%) workplaces Der f 1 in 87 (55%), Fel d 1 in 86 (54%) and Bla g 2 in 3 (1.9%). Der p 1 allergen concentrations expressed per weight were higher than the proposed sensitization thresholds in 7 samples, Der f 1 in 5, Fel d 1 in 6 and Bla g 2 in 3. The highest allergen levels were detected in samples from upholstered seats. A significant correlation was found between Der f 1 level on floors, expressed per surface, and indoor temperature (r = 0.39; P < 0.01).

CONCLUSIONS

In our study we found that upholstered seats in workplaces in Italy may constitute a significant reservoir both of house dust mites and cat allergens. Exposure to these allergens in workplaces may represent a risk factor for elicitation of symptoms and/or induction/maintenance of inflammation in allergic individuals and might also constitute a risk factor for sensitization.

Low energy electronic excitations in the layered cuprates studied by copper L3 resonant inelastic x-ray scattering

We have measured the resonant inelastic x-ray scattering (RIXS) spectra at the Cu L3 edge in a variety of cuprates. Exploiting a considerably improved energy resolution (0.8 eV) we recorded significant dependencies on the sample composition and orientation, on the scattering geometry, and on the incident photon polarization. The RIXS final states correspond to two families of electronic excitations, having local (dd excitations) and nonlocal (charge-transfer) character. The dd energy splitting can be estimated with a simple crystal field model. The RIXS at the L3 edge demonstrates here a great potential, thanks to the resonance strength and to the large 2p spin-orbit splitting.

Exacerbation of asthma related to Eucalyptus pollens and to herb infusion containing Eucalyptus

Eucalyptus is known as a potential cause of cutaneous diseases due to contact with oil or pollens, and of respiratory allergic diseases due to exposure to pollens. We report the case of a 30-year-old woman with asthma and rhinoconjunctivitis in which symptoms appeared to be exacerbated by Eucalyptus pollens and by ingestion of an infusion containing Eucalyptus. Specific IgE were positive for Eucalyptus pollens and negative for common aeroallergens. Our report shows that Eucalyptus may elicit asthma and rhinitis with an IgE-mediated mechanism both by inhalation of pollens and by ingestion of herb infusions, and suggests that care should be taken in administering herbal medications in asthmatic subjects.

Spectroscopic signatures of a bandwidth-controlled Mott transition at the surface of 1T-TaSe2

High-resolution angle-resolved photoemission data show that a metal-insulator Mott transition occurs at the surface of the quasi-two-dimensional compound 1T-TaSe2. The transition is driven by the narrowing of the Ta 5d band induced by a temperature-dependent modulation of the atomic positions. A dynamical mean-field theory calculation of the spectral function of the half-filled Hubbard model captures the main qualitative feature of the data, namely, the rapid transfer of spectral weight from the observed quasiparticle peak at the Fermi surface to the Hubbard bands, as the correlation gap opens up.

A case of indirect exposure to cat at school

Indirect exposure to cat allergens may exacerbate asthma in sensitized subjects. We report a case of a 13-year-old girl referred to our Unit for cough, dyspnea, wheezing, chest tightness, nasal itching and obstruction during the past six months, with improvement during summer holidays. Skin prick tests were positive for cat and Alternaria alternata. She had no cats at home. Spirometry was normal and methacoline bronchial challenge was negative. PEF monitoring showed a mean value of 80% of the predicted value with a variability higher than 20% in a few occasions. At a follow up visit PEF recording showed an increase of 80 litres/min during a 2 weeks Christmas holidays, and a subsequent reduction after being back at school. At a further questioning we found that in her class there was a girl who owned 23 cats. It is likely that PEF and symptoms in our patient were affected by indirect cat exposure at school.

The impact of climate and traffic-related NO2 on the prevalence of asthma and allergic rhinitis in Italy

BACKGROUND

Environmental factors are likely to be involved in explaining the wide geographical variation in asthma and atopic diseases that has been documented in many recent epidemiological studies.

AIM

To evaluate to what extent climate and outdoor NO2 pollution can explain the geographical variation in the prevalence of asthma and allergic rhinitis, and to estimate the relative risk for exposure to different levels of these two factors.

METHODS

The impact of climate and long-term exposure to nitrogen dioxide (NO2) pollution on asthma and allergic rhinitis was assessed in a cross-sectional study, carried out during 1998 to 2000 on young adults aged 20 to 44 years (n = 18 873), living in 13 areas from two different Italian climatic regions (subcontinental and Mediterranean).

RESULTS

Mediterranean areas had a significantly higher prevalence of asthma-like symptoms (P < 0.001), higher annual mean temperature (16.2 degrees C vs. 12.9 degrees C), lower temperature range (16.0 C degrees vs. 22.1 degrees C) and lower NO2 levels (31.46 microg/m3 vs. 57.99 microg/m3) than subcontinental ones. Mediterranean climate was associated with an increased risk of wheeze (OR = 1.23; 95% CI 1.13 to 1.35), tightness in the chest (OR = 1.21; 95% CI 1.11 to 1.33), shortness of breath (OR = 1.21; 95% CI 1.08 to 1.36) and asthma attacks (OR = 1.19; 95% CI 1.07 to 1.31). After adjusting for climate, an increase of 18.3 microg/m3 in NO2 levels moderately increased the risk of asthma attacks (OR = 1.13; 95% CI 0.98 to 1.32), tightness in the chest (OR = 1.11; 95% CI 0.98 to 1.26) and wheeze (OR = 1.11; 95% CI 0.96 to 1.28). When the levels of outdoor NO2 exposure rose, the prevalence of allergic rhinitis increased significantly in the Mediterranean region (OR = 1.38; 95% CI 1.12 to 1.69), but not in the subcontinental one (OR = 1.03; 95% CI 0.83 to 1.28).

CONCLUSION

Our results show that the prevalence of asthma increases when annual mean temperature increases and temperature range decreases. Furthermore, climate interacts with NO2 outdoor exposure, increasing the risk for allergic rhinitis in people exposed to high stable temperatures. A long-term role for the effect of traffic pollution on asthma is also suggested.

Increased CD69 expression on peripheral blood eosinophils after specific inhalation challenge

BACKGROUND

CD69 is a molecule expressed on human eosinophils after cytokine-activation. Different studies have described the eosinophil activation, evaluated by CD69 expression, at the site of an allergic inflammation. In this study we evaluated the expression of CD69 on peripheral blood eosinophils after a specific inhalation challenge (SIC), in order to better define the state of activation of peripheral blood eosinophils after exposure to sensitizers.

METHODS

CD69 expression was evaluated by flow cytometry in nine asthmatic patients before and after a positive SIC with high or low molecular weight agents (pollens, house dust mites, Penicillia, isocyanates) and in 11 asthmatic patients who underwent an inhalation challenge with placebo. CD69 expression was evaluated at baseline, 120 min, and 240 min after the SIC or the placebo.

RESULTS

Baseline (before challenge) CD69 expression was comparable between the group of SIC positive patients and the placebo group. CD69 expression on peripheral eosinophils significantly increased 240 min after the challenge in positive SIC patients compared to placebo. In patients with a positive SIC the percentage of peripheral blood eosinophils significantly decreased at 120 and 240 min after the inhalation challenge with respect to the baseline.

CONCLUSION

CD69 expression on peripheral blood eosinophils is significantly increased in asthmatic patients after exposure to the sensitizing agent. These data show that the effects of a bronchial stimulation are also detectable on peripheral blood eosinophils.

Spectroscopic indications of polaronic carriers in the quasi-one-dimensional conductor (TaSe4)2I

Angle-resolved photoemission (ARPES) on the quasi-one-dimensional conductor (TaSe4)2I shows a hidden Fermi-surface crossing in its metallic state and the opening of a Peierls gap at low temperatures. The underlying quasiparticles have vanishing spectral weight and extremely short coherence lengths. They are interpreted as polarons in the strong-coupling adiabatic limit, and almost all their ARPES weight is incoherent. These observations suggest a scenario where the long-standing contradictions between ARPES and other experiments on Peierls materials could be resolved.

Worsening of asthma in children allergic to cats, after indirect exposure to cat at school

Exposure to cat allergen at school might exacerbate symptoms in asthmatic children with cat allergy. To study this, we identified 410 children, 6-12 yr of age, who were being treated for asthma (inhaled steroids and beta-agonists), were allergic to cats, and had no cat at home. Peak expiratory flow (PEF), asthma symptoms, medication, fever and/or sore throat, and contact with furred pets were recorded twice daily during the last week of summer holidays and the second and third weeks of school. The number of cat owners in each class was recorded. Ninety-two children with asthma reported no contact with furred pets. Among these, children who attended classes with > 18% (median value) cat owners reported significantly decreased PEF, more days with asthma symptoms, and increased use of medication after school started. Those in classes with < or = 18% cat owners reported no change. Children in classes with many cat owners ran a 9-fold increased risk of exacerbated asthma after school start compared with children in classes with few cat owners, after adjusting for age, sex, and fever and/or sore throat. Thus, asthma symptoms, PEF, and the use of asthma medication in children with cat allergy may be affected by indirect cat exposure at school.

[Sampling of allergens in dust deposited in the workplace]

Some workplaces share with domestic dwellings many characteristics favouring house dust mite growth. Moreover it has recently been shown that pets owners can bring allergens to public places with their clothes. So it is possible that significant exposure to indoor allergens can occur outside homes, at the workplace. The recent availability of immunoassays with monoclonal antibodies for indoor allergens has enabled many investigators to quantify exposure to such allergens in epidemiological studies. Analysis of allergens in settled dust is a simple method of quantification exposure to indoor allergens. The concentrations of indoor allergens in public places have already been investigated and high levels of indoor allergens have been reported. A study performed by our group in offices (banks and media) in different regions of Italy has also shown significant levels of indoor allergens. Thus, evaluating exposure to indoor allergens at the workplace is critical to evaluate risk factors for sensitization and elicitation of symptoms in sensitized subjects and such data help in addressing correctly the problem of reducing exposure levels.

Electronic structure of solids with competing periodic potentials

When electrons are subject to a potential with two incommensurate periods, translational invariance is lost, and no periodic band structure is expected. However, model calculations based on nearly free one-dimensional electrons and experimental results from high-resolution photoemission spectroscopy on a quasi-one-dimensional material do show dispersing band states with signatures of both periodicities. Apparent band structures are generated by the nonuniform distribution of electronic spectral weight over the complex eigenvalue spectrum.

Levels of house-dust-mite allergen in homes of nonallergic people in Pavia, Italy

BACKGROUND

HDM distribution varies between geographic areas and may be affected by housing characteristics. We quantified Der p 1 and Der f 1 and assessed the relationships between their levels and housing characteristics in homes of nonallergic subjects.

METHODS

Der f 1 and Der p 1 were measured by ELISA in dust samples from living-room floors and mattresses of 44 homes of nonallergic subjects in Pavia. Information about household characteristics was obtained by questionnaire.

RESULTS

Der p 1 and Der f 1 concentrations (microg/g dust, median) were 0.34 and 7.8 on mattresses, and 0.15 and 0.83 on living-room floors. Higher Der f 1 levels on mattresses were associated with synthetic pillows (P<0.05), and (only when expressed as microg/m2) with bedding washing temperature of < or = 60 degrees C (P<0.05). Der f 1 levels were higher on the living-room floors of homes located on lower (< or =first) floors (P<0.05). Good correlations were found between Der p 1 and Der f 1 expressed as microg/g dust and microg/m2 on both mattresses and living-room floors.

CONCLUSIONS

In homes of nonallergic subjects in northern Italy, Der f 1 exceeded the threshold for sensitization in a high proportion of mattress samples.

Spectromicroscopy of boron in human glioblastomas following administration of Na2B12H11SH

Boron neutron capture therapy (BNCT) is an experimental, binary treatment for brain cancer which requires as the first step that tumor tissue is targeted with a boron-10 containing compound. Subsequent exposure to a thermal neutron flux results in destructive, short range nuclear reaction within 10 microm of the boron compound. The success of the therapy requires than the BNCT agents be well localized in tumor, rather than healthy tissue. The MEPHISTO spectromicroscope, which performs microchemical analysis by x-ray absorption near edge structure (XANES) spectroscopy from microscopic areas, has been used to study the distribution of trace quantities of boron in human brain cancer tissues surgically removed from patients first administered with the compound Na2B12H11SH (BSH). The interpretation of XANES spectra is complicated by interference from physiologically present sulfur and phosphorus, which contribute structure in the same energy range as boron. We addressed this problem with the present extensive set of spectra from S, B, and P in relevant compounds. We demonstrate that a linear combination of sulfate, phosphate and BSH XANES can be used to reproduce the spectra acquired on boron-treated human brain tumor tissues. We analyzed human glioblastoma tissue from two patients administered and one not administered with BSH. As well as weak signals attributed to BSH, x-ray absorption spectra acquired from tissue samples detected boron in a reduced chemical state with respect to boron in BSH. This chemical state was characterized by a sharp absorption peak at 188.3 eV. Complementary studies on BSH reference samples were not able to reproduce this chemical state of boron, indicating that it is not an artifact produced during sample preparation or x-ray exposure. These data demonstrate that the chemical state of BSH may be altered by in vivo metabolism.

UV-ozone ashing of cells and tissues for spatially resolved trace element analysis

UV/ozone ashing of thin tissue sections and cell cultures is a simple technique to enhance relative elemental concentrations, while maintaining their spatial location at the sub-micron level. This approach may enhance the capability of spatially resolved analysis techniques to detect the distribution of trace elements in biological matrices. We present results from light microscopy and x-ray spectromicroscopy studies of tissues and cells demonstrating that the micro-structure is very well conserved. We show the signal enhancement resulting from the removal of carbon, which allows otherwise undetectable gadolinium to be mapped in cancer tissue for a novel neutron capture therapy.

Serum eosinophil cationic protein (sECP) in subjects with a history of asthma symptoms with or without rhinitis

BACKGROUND

Serum eosinophil cationic protein (sECP) has been proposed as a marker of disease activity in bronchial asthma. The study aimed to evaluate the role of sECP in screening asthmatics in a group of subjects with asthma and rhinitis symptoms, and the relationship between sECP and clinical and functional parameters of asthma.

METHODS

A total of 185 subjects with asthma symptoms, 149 of them with rhinitis as well, underwent skin tests, spirometry, methacholine (MCH) test, blood sampling for eosinophil percentage (bEOS%) and sECP determination, and nasal secretions smear for eosinophil percentage (nEOS%) determination; PEF values, symptoms, and medication over a period of 4 weeks after sampling for sECP quantitation were recorded on a diary.

RESULTS

A total of 99 (53%) subjects received a diagnosis of asthma (asthmatics), and 86 did not (nonasthmatics). In asthmatics, neither sECP nor bEOS% was significantly different from nonasthmatics. In asthmatics, sECP was higher in subjects with increased than in those with normal daily PEF variability (16.4, 6.8-24.4 vs 5.3, 3.9-8.4 microg/l; P<0.001). sECP was higher in moderate persistent asthma than in intermittent asthma (24.8, 10.6-53 vs 8.4, 5.6-14.1; P<0.05). In nonasthmatics (73 with a history of rhinitis), both sECP and bEOS% correlated with nEOS% (rho=0.35; P<0.01 and rho=0.53; P<0.001).

CONCLUSIONS

In adults with asthma symptoms with or without rhinitis, sECP did not distinguish asthmatics from nonasthmatics. In asthmatics, sECP was associated with PEF variability and symptom severity. In subjects with asthma and rhinitis, as well as in subjects with only rhinitis, sECP levels are possibly influenced by nasal inflammation.

Cell ashing for trace element analysis: A new approach based on ultraviolet/ozone

We studied a new approach to cell ashing based on illuminating the specimens with a low-pressure mercury discharge lamp. We analyzed with synchrotron spectromicroscopy its effects on different physiological elements in neurobiological specimens. Our results demonstrate that carbon is removed, whereas phosphorus, calcium, potassium, and sulfur are retained and their relative concentrations are enhanced. Applied to trace elements, this technique will enhance their practical detectability.