Hierarchically Structured Magnetic Nanoconstructs with Enhanced Relaxivity and Cooperative Tumor Accumulation

Iron oxide nanoparticles are formidable multifunctional systems capable of contrast enhancement in magnetic resonance imaging, guidance under remote fields, heat generation, and biodegradation. Yet, this potential is underutilized in that each function manifests at different nanoparticle sizes. Here, sub‐micrometer discoidal magnetic nanoconstructs are realized by confining 5 nm ultra‐small super‐paramagnetic iron oxide nanoparticles (USPIOs) within two different mesoporous structures, made out of silicon and polymers. These nanoconstructs exhibit transversal relaxivities up to ≈10 times (r ₂ ≈ 835 mm ^?1 s^?1) higher than conventional USPIOs and, under external magnetic fields, collectively cooperate to amplify tumor accumulation. The boost in r ₂ relaxivity arises from the formation of mesoscopic USPIO clusters within the porous matrix, inducing a local reduction in water molecule mobility as demonstrated via molecular dynamics simulations. The cooperative accumulation under static magnetic field derives from the large amount of iron that can be loaded per nanoconstuct (up to ≈65 fg) and the consequential generation of significant inter‐particle magnetic dipole interactions. In tumor bearing mice, the silicon‐based nanoconstructs provide MRI contrast enhancement at much smaller doses of iron (≈0.5 mg of Fe kg^?1 animal) as compared to current practice.     

Polycyclic aromatic hydrocarbons in olive oils on the Italian market.

The six olive oils and seven virgin olive oils which are most consumed in Italy were analysed for 28 polycyclic aromatic hydrocarbons (PAHs). The aim was to evaluate whether a carcinogenic hazard for the general population can derive from the dietary intake of this food, which is consumed particularly highly in the Mediterranean area. The analytical method involved extraction by liquid-liquid partition, filtration on silica gel, clean-up by thin-layer chromatography on silica gel, and analysis by high-resolution gas chromatography with a flame ionization detector. The 3- and 4-ring PAHs which are most abundant in the environment were found in all samples, at individual levels up to ca. 40 micrograms/kg (for phenanthrene); no important difference was observed between olive oils and virgin olive oils. PAHs which are most suspected of being carcinogenic for humans were not detected (limit of detection, ca. 3 micrograms/kg). The average yearly intake of the detected PAHs through this food was estimated at ca. 0.56 mg per capita.     

Early development of properties in a cement paste: A numerical and experimental study

This paper presents the results of an experimental and numerical study of the properties of a high-performance Portland cement paste (w/c ratio 0.37; 5% silica fume) cured at 20 °C in sealed conditions for 5 days. Properties such as electrical conductivity, strength, stiffness, porosity, Vicat penetration, and autogenous deformation were measured and modelled. The kinetics of hydration was studied by means of isothermal calorimetry. The numerical simulations were performed with CEMHYD3D, developed at the National Institute of Standards and Technology, and HYMOSTRUC, developed at the Delft University of Technology. The results of the simulations were compared with experimental data, and the match was good. Clear correlations were found among electrical conductivity, autogenous shrinkage, and connectivity of solids.     

Numerical prediction of turbulent convective heat transfer in mini/micro channels for carbon dioxide at supercritical pressure

A new approach to take into account the effects of variable physical properties on turbulence is suggested. It allows to choose freely the turbulent closure model for conventional terms due to velocity fluctuations and to describe coherently the additional terms due to density fluctuations. Numerical calculations based on the suggested approach have been performed for carbon dioxide flowing within mini/micro channels under cooling conditions. The numerical predictions show that the effects due to density fluctuations are smaller than it could have been initially supposed and that the heat transfer impairment for mini/micro channels, which some experiments seem to highlight, is not completely explained by the considered model.     

Reactivation of Chagas' disease in a human immunodeficiency virus-infected patient leading to severe heart disease with a late positive direct microscopic examination of the blood

We report a human immunodeficiency virus (HIV)-infected man with chronic Chagas' disease who developed a congestive heart failure that could not be clinically controlled. Endomyocardial biopsy revealed severe myocarditis and the xenodiagnosis result was positive, but Trypanosoma cruzi by direct microscopic examination of the blood was found only four months after the symptoms had started. Treatment with benznidazole was effective in reducing parasitemia, stabilizing the clinical status, and controlling tissue damage related to the parasite. Although the finding of T. cruzi trypomastigotes by direct microscopic examination of the blood has been considered the mark of Chagas' reactivation in immunocompromised patients with chronic disease, in this case it was a late finding.     

Chlamydia pneumoniae infection and cardiac ischemic syndromes

The aim of this study was to assess the presence of Chlamydia pneumoniae antibodies in patients with angiographically verified atherosclerotic coronary artery disease. A total of 114 consecutive patients were investigated between April 1995 and June 1996. Patients were divided into two groups: 72 patients with acute myocardial infarction (AMI; 53 men, 19 women, mean age 62.27 +/- 10.1 years), and 42 patients with chronic ischemic heart disease (CAD; 37 men, 5 women, mean age 62.75 +/- 9.2 years). A control group of 50 normal subjects matched for age (mean 62 +/- 9 years), sex, social status and geographical area was used. Identification of Chlamydia pneumoniae was carried out with the microimmunofluorescence method, on two serum samples taken from patients on admission and after 15 days. The IgM, IgG and IgA anti-Chlamydia pneumoniae titers were assessed, values > or = 1:16, > or = 1:32 and > or = 1:8 being respectively considered positive. Acute (IgM > or = 16 or four fold rise of IgG titer) and chronic (IgG > or = 128 e IgA > or = 32 or only elevated IgA titer) infections were analyzed. IgM antibodies were not found in AMI, CAD and control groups. IgG positivity (IgG > or = 32) was found in 38% of the control group, in 58.3% of the AMI group (p < 0.05) and 42.8% of the CAD group (p < 0.01). IgA positivity > or = 8) was found in 22% of the control group, in 31.9% of the AMI group (NS) and in 33.3% of the CAD group (p < or = 0.05). Acute infection was observed in 5.5% of AMI patients and in 12% of CAD patients (NS), whereas no subject of the control group showed these values. Chronic infection was observed in 9.7% of AMI patients and in 16.6% of CAD patients (NS) whereas nobody of the control group showed these values. In conclusion, our results suggest that Chlamydia pneumoniae infection is present only in the AMI and CAD groups. It is possible to suppose that this infection may be linked to atherosclerosis through an endothelial damage or a systemic endogenous procoagulant and inflammatory activity.     

The influence of photon peak arrival in the timing of plastic scintillators by means of pulsed laser and optical fibers

The influence of photon peak arrival in the laser-optical fibers timing system of a large array of plastic scintillators has been studied for different types of photomultipliers. The obtained results, helpful in properly designing the system are presented and discussed.