252 research outputs found
Synthesis and characterization of TiO2 nanotubes as anodic material in lithium-ion batteries
The aim of this work is to analyze the efficiency of titania nanotubes acting as anode for lithium-ion batteries. The titania nanotubes has been obtained using an anodization process in a ethylene glycol solution, containing ammonium fluoride and a small quantity of water. After a heat treatment, needed to crystallize the material in the anatase form, the nanotubes has been analyzed in their performance as anode in a Li-ion battery. Structural and morphologic characterization of the titania nanotubes have been studied using XRD and SEM analysis, while the galvanostatic cycles has been collected in order to examine the electrochemical performance as electrodic material. Finally, a comparison of the electrochemical performance between our samples and commercial nanostructured titanium oxide, has been made, obtaining that the TiO2 nanotube electrodes treatmen reduces the overall cell voltage and provides good retention capacity on cycling and higher capacity at all used C-rate
Titanium nanotubes stimulate osteoblast differentiation of stem cells from pulp and adipose tissue
BACKGROUND:
Titanium is the gold standard among materials used for prosthetic devices because of its good mechanical and chemical properties. When exposed to oxygen, titanium becomes an oxide, anatase that is biocompatible and able to induce osseointegration.
MATERIALS AND METHODS:
IN THIS STUDY WE COMPARED THE EXPRESSION PROFILING OF STEM CELLS CULTIVATED ON TWO TYPES OF SURFACE: Pure titanium disk and nanotube titanium disk in order to detect if nanotube titanium instead (NTD) surface stimulates stem cells towards osteoblast differentiation.
RESULTS:
Stem cells cultivated on nanotube titanium disks showed the upregulation of bone-related genes RUNX2, FOSL1 and SPP1.
CONCLUSIONS:
Results demonstrated that nanotube titanium disk surface is more osteo-induced surface compared to titanium disk, promoting the differentiation of mesenchymal stem cells in osteoblasts
Study on the Durability of Recast Nafion/Montmorillonite Composite Membranes in Low Humidification Conditions
Nafion composite membranes were formed from a recasting procedure previously reported by the authors. Montmorillonite (MMT) was used as a filler in the recasting procedure, and dimethylformamide (DMF) was used as the casting solvent. Fuel cell tests performed with the recast membrane showed that at low relative humidity (R.H.) the conductivity of the MMT-containing membranes is 10% higher than that of the MMT-free samples. In order to investigate the durability of such composite perfluorosulfonate membranes, long-term fuel cell experiments have been carried out. Results evidenced a strong effect of low RH on the lifetime of commercial polymer membranes, but the addition of a small silicate amount to the polymeric membrane reduced strongly the membrane degradation
Fast and Reliable Differentiation of Eight Trichinella Species Using a High Resolution Melting Assay
High resolution melting analysis (HRMA) is a single-tube method, which can be carried out rapidly as an additional step following real-time quantitative PCR (qPCR). The method enables the differentiation of genetic variation (down to single nucleotide polymorphisms) in amplified DNA fragments without sequencing. HRMA has previously been adopted to determine variability in the amplified genes of a number of organisms. However, only one work to date has focused on pathogenic parasites–nematodes from the genus Trichinella. In this study, we employed a qPCR-HRMA assay specifically targeting two sequential gene fragments–cytochrome c oxidase subunit I (COI) and expansion segment V (ESV), in order to differentiate 37 single L1 muscle larvae samples of eight Trichinella species. We prove that qPCR-HRMA based on the mitochondrial COI gene allows differentiation between the sequences of PCR products of the same length. This simple, rapid and reliable method can be used to identify at the species level single larvae of eight Trichinella taxa.High resolution melting analysis (HRMA) is a single-tube method, which can be carried out rapidly as an additional step following real-time quantitative PCR (qPCR). The method enables the differentiation of genetic variation (down to single nucleotide polymorphisms) in amplified DNA fragments without sequencing. HRMA has previously been adopted to determine variability in the amplified genes of a number of organisms. However, only one work to date has focused on pathogenic parasites–nematodes from the genus Trichinella. In this study, we employed a qPCR-HRMA assay specifically targeting two sequential gene fragments–cytochrome c oxidase subunit I (COI) and expansion segment V (ESV), in order to differentiate 37 single L1 muscle larvae samples of eight Trichinella species. We prove that qPCR-HRMA based on the mitochondrial COI gene allows differentiation between the sequences of PCR products of the same length. This simple, rapid and reliable method can be used to identify at the species level single larvae of eight Trichinella taxa
Trichinella pseudospiralis outbreak in France.
Four persons became ill with trichinellosis after eating meat from a wild boar hunted in Camargue, France. Nonencapsulated larvae of Trichinella pseudospiralis were detected in meat and muscle biopsy specimens. The diagnoses were confirmed by molecular typing. Surveillance for the emerging T. pseudospiralis should be expanded
Investigation on Opisthorchis felineus occurrence and life cycle in Italy
Opisthorchiasis is a fish borne parasitic infection caused by helminths of the genus
Opisthorchis (Digenea, Opisthorchiidae), affecting humans and other fish-eating mammals.
Despite Opisthorchis felineus was first described in Italy in 1884, no cases of human
opisthorchiasis were reported in this country until 2004; from then on, 4 outbreaks due to
this species have been recorded in Central Italy. Following the more relevant of these outbreaks,
involving 34 people in August 2007, snails, fishes and fecal samples collected from
the Bolsena and Bracciano lakes (Central Italy) were analyzed in order to define the cycle
of O. felineus in the area and investigate its prevalence in the different hosts. Pools of 20–40
snails each (4983 specimens altogether) of the genus Bithynia were analyzed by PCR for
parasite DNA detection. Eight hundred and ninety-four fish belonging to 12 species were
collected from the two lakes and tested for metacercariae both by muscle compression and
digestion techniques. Eighty-seven fecal samples of 5 putative definitive host species were
collected very close to the two lakes and tested for parasite eggs detection by formalin–ethyl
acetate concentration technique. Identification at the species level of metacercariae and
eggs, respectively, from fish and stool was confirmed by PCR analysis and sequencing. O.
felineus DNA was detected in 0.08% (overall minimum infection rate) of snails of the genus
Bithynia from the two lakes. The tench, Tinca tinca, was the only fish found infested in both
lakes (prevalence 88.5%). O. felineus eggs were found only in cat feces (prevalence 46.4%).
The tench represents the only threat for the human consumption in the study area while
Coregonus sp., the most economically important species for the local fishery and frequently
consumed raw marinated, resulted to be not infected. The high prevalence recorded both
in fish and in definitive host suggests a widespread and massive presence of the parasite in
the area. Further studies are needed to better investigate the possible role of some cyprinids
species as intermediate hosts, in order to check their safety for human consumption
Lithium Depletion in Fully Convective Pre-Main Sequence Stars
We present an analytic calculation of the thermonuclear depletion of lithium
in contracting, fully convective, pre-main sequence stars of mass M < 0.5
M_sun. Previous numerical work relies on still-uncertain physics (atmospheric
opacities and convection, in particular) to calculate the effective temperature
as a unique function of stellar mass. We assume that the star's effective
temperature, T_eff, is fixed during Hayashi contraction and allow its actual
value to be a free parameter constrained by observation. Using this
approximation, we compute lithium burning analytically and explore the
dependence of lithium depletion on T_eff, M, and composition. Our calculations
yield the radius, age, and luminosity of a pre-main sequence star as a function
of lithium depletion. This allows for more direct comparisons to observations
of lithium depleted stars. Our results agree with those numerical calculations
that explicitly determine stellar structure during Hayashi contraction. In
agreement with Basri, Marcy, and Graham (1996), we show that the absence of
lithium in the Pleiades star HHJ 3 implies that it is older than 100 Myr. We
also suggest a generalized method for dating galactic clusters younger than 100
Myr (i.e., those with contracting stars of M > 0.08 M_sun) and for constraining
the masses of lithium depleted stars.Comment: 13 pages, LaTex with 2 postscript figures, uses aaspp4.sty and
epsfig.sty, to appear in the Astrophysical Journa
A Sample of Very Young Field L Dwarfs and Implications for the Brown Dwarf "Lithium Test" at Early Ages
Using a large sample of optical spectra of late-type dwarfs, we identify a
subset of late-M through L field dwarfs that, because of the presence of
low-gravity features in their spectra, are believed to be unusually young. From
a combined sample of 303 field L dwarfs, we find observationally that
7.6+/-1.6% are younger than 100 Myr. This percentage is in agreement with
theoretical predictions once observing biases are taken into account. We find
that these young L dwarfs tend to fall in the southern hemisphere (Dec < 0 deg)
and may be previously unrecognized, low-mass members of nearby, young
associations like Tucana-Horologium, TW Hydrae, beta Pictoris, and AB Doradus.
We use a homogeneously observed sample of roughly one hundred and fifty
6300-10000 Angstrom spectra of L and T dwarfs taken with the Low-Resolution
Imaging Spectrometer at the W. M. Keck Observatory to examine the strength of
the 6708-A Li I line as a function of spectral type and further corroborate the
trends noted by Kirkpatrick et al. (2000). We use our low-gravity spectra to
investigate the strength of the Li I line as a function of age. The data weakly
suggest that for early- to mid-L dwarfs the line strength reaches a maximum for
a few 100 Myr, whereas for much older (few Gyr) and much younger (<100 Myr) L
dwarfs the line is weaker or undetectable. We show that a weakening of lithium
at lower gravities is predicted by model atmosphere calculations, an effect
partially corroborated by existing observational data. Larger samples
containing L dwarfs of well determined ages are needed to further test this
empirically. If verified, this result would reinforce the caveat first cited in
Kirkpatrick et al. (2006) that the lithium test should be used with caution
when attempting to confirm the substellar nature of the youngest brown dwarfs.Comment: 73 pages with 22 figures; to appear in ApJ (Dec 20, 2008, v689n2
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