The direct synthesis of a mesostructured silica with a tridimensional mesopore network with micrometer-sized and -shaped particles control is reported for the first time. Micrometer-sized beads of ...the cubic silica mesostructure MCM-48 have been obtained through a MCM-41 pseudomorphic synthesis procedure using preformed porous silica particles as silica source combined with a MCM-41/-48 phase transition. The low degree of polymerization of the MCM-41 formed in high alkaline conditions allows the further MCM-41/-48 phase transition. The kinetics of MCM-48 formation depends on the surface area of the parent silica, indicating that the dissolution of the silica in a confined environment is the rate-determining step of the process. The reaction time required to produce MCM-48 decreases from 7 to 2 h when the surface area of the parent silica increases from 160 to 740 m2/g. The MCM-48 mesostructure is metastable toward a lamellar mesostructure at longer synthesis times (>20 h). The domain of existence of the different mesostructures as a function of synthesis time and surface area of the parent silica sources has been established. The aggregation state of the MCM-48 particles can be controlled by adjusting the dilution and the alkalinity of the synthesis medium.
Hydrocolloid-forming polysaccharides are natural polyelectrolytes able to form stable hydrogels largely used in the food and pharmaceutical industry. Gelling polysaccharides derived from seaweeds or ...wastes of the seafood industry include polymers with several functional groups: alginates (carboxylic groups), carrageenans (sulfonic groups) and chitosan (amino groups). This article deals with suitable methods to prepare dry materials which retain the dispersion of the polymer hydrogel, namely polysaccharide aerogels. The materials whose properties are herewith described satisfy most of the appropriate requirements for heterogeneous catalysts and supports: they are stable in most organic solvents, present a high surface area and diverse accessible surface functionalities. Their application as catalysts, catalyst supports or adsorbents provide a new opportunity to obtain useful materials from one of the less energy-intensive sources of biomass.
Histone deacetylases (HDAC) control gene expression by changing histonic as well as non histonic protein conformation. HDAC inhibitors (HDACi) are considered to be among the most promising drugs for ...epigenetic treatment for cancer. Recently a strict relationship between histone hyperacetylation in specific tissues of mouse embryos exposed to two HDACi (valproic acid and trichostatin A) and specific axial skeleton malformations has been demonstrated. The aim of this study is to verify if boric acid (BA), that induces in rodents malformations similar to those valproic acid and trichostatin A-related, acts through similar mechanisms: HDAC inhibition and histone hyperacetylation.
Pregnant mice were treated intraperitoneally with a teratogenic dose of BA (1000 mg/kg, day 8 of gestation). Western blot analysis and immunostaining were performed with anti hyperacetylated histone 4 (H4) antibody on embryos explanted 1, 3 or 4 h after treatment and revealed H4 hyperacetylation at the level of somites. HDAC enzyme assay was performed on embryonic nuclear extracts. A significant HDAC inhibition activity (compatible with a mixed type partial inhibition mechanism) was evident with BA. Kinetic analyses indicate that BA modifies substrate affinity by a factor
α
=
0.51 and maximum velocity by a factor
β
=
0.70. This work provides the first evidence for HDAC inhibition by BA and suggests such a molecular mechanism for the induction of BA-related malformations.
The impregnation of a carrageenan gel by a silica sol is an efficient method to form a composite material which can be conveniently activated by CO
2 supercritical drying. The textural properties of ...the solids have been characterized by nitrogen adsorption–desorption at 77 K and their composition by thermogravimetric analysis and EDX microprobe. Morphology was examined by SEM. The silica–carrageenan composites present an open macroporous structure. Silica particles retained inside the gel behaved as pillars between the polysaccharide fibrils and form a stick-and-ball network. The stiffening of the carrageenan gel by silica prevented its shrinkage upon drying. The nature of the alkali cations affected the retention of silica particles inside the gel. In the absence of silica, carrageenan fibrils rearrange under supercritical drying and form an aerogel with cavities in the mesopore range.
A composite presenting an open stick-and-ball structure was obtained by impregnation of carrageenan hydrogel beads by a silica sol.
The treatment of platinum resistant/refractory epithelial ovarian cancer (EOC) is a challenge for oncologists. One of the most utilized drugs in these patients is pegylated liposomal doxorubicin ...(PLD). As PLD is active only in a small subset of patients and causes side effects, selection of responsive patients is an unmet need and might be guided by the status of the DNA topoisomerase II alpha (TOP2A) that is poisoned by the drug.
From 176 ovarian cancers treated in three institutions, we selected 38 patients treated with PLD monotherapy as second/third line of treatment. TOP2A gene copies were measured using Fluorescent In Situ Hybridization (FISH) and expression evaluated using immunohistochemistry. Patients' derived xenografts (PDXs) of ovarian cancers were used to assess the correlation between TOP2A protein expression and response to PLD.
Clinical data showed that TOP2A gene gain that is paralleled by increased expression of the protein, was associated with a higher probability of clinical benefit from PLD. Treatment of PDXs demonstrated that only xenografts showing a high percentage of TOP2A expressing cells underwent tumor shrinkage when treated with PLD.
These data show that TOP2A gene gain and protein over-expression might predict activity of PLD in platinum resistant/refractory EOC.
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► The relative stability of zeolitic phases depends on the composition of the solution. ► Solubility diagrams of aluminosilicate zeolites from partial dissolution experiments. ► ...Excess silicate drives dissolution of faujasite in the synthesis of zeolite omega.
The transient formation of faujasite has been observed during the synthesis of zeolite omega. The metastability between these zeolites has been studied by measuring their solubilities in alkaline solutions at temperature levels near to usual crystallization conditions. The use of silicate- and aluminate-enriched solutions has allowed to determine solubility curves at different alkalinity levels. The silicate concentration in solution controls the relative stability of the two structures. For Si/Al ratios in solution lower than 6–10 (80–115
°C), zeolite omega is more soluble than faujasite and can be dissolved to provide silicate and aluminate for the crystallization of aluminium-richer zeolite X. In the usual conditions for the synthesis of zeolite omega, with Si/Al in solution higher than 100, zeolite X is metastable and is dissolved to provide aluminate for the crystallization of silica-richer zeolite omega.
Sperm protein 17 (Sp17) was originally identified in the flagellum of spermatozoa and subsequently included in the subfamily of tumor-associated antigens known as cancer-testes antigens (CTA). Sp17 ...has been associated with the motility and migratory capacity in tumor cells, representing a link between gene expression patterns in germinal and tumor cells of different histological origins. Here we review the relevance of Sp17 expression in the mouse embryo and cancerous tissues, and present additional data demonstrating Sp17 complex expression pattern in this murine model. The expression of Sp17 in embryonic as well as adult neoplastic cells, but not normal tissues, suggests this protein should be considered an "oncofetal antigen." Further investigations are necessary to elucidate the mechanisms and functional significance of Sp17 aberrant expression in human adult cells and its implication in the pathobiology of cancer.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Texture-related features of water intrusion in hydrophobised MCM-41 silicas render these materials especially suitable for energy dissipation in mechanical dampers.
Current interferometric gravitational-wave detectors are limited by quantum noise over a wide range of their measurement bandwidth. One method to overcome the quantum limit is the injection of ...squeezed vacuum states of light into the interferometer's dark port. Here, we report on the successful application of this quantum technology to improve the shot noise limited sensitivity of the Advanced Virgo gravitational-wave detector. A sensitivity enhancement of up to 3.2±0.1 dB beyond the shot noise limit is achieved. This nonclassical improvement corresponds to a 5%-8% increase of the binary neutron star horizon. The squeezing injection was fully automated and over the first 5 months of the third joint LIGO-Virgo observation run O3 squeezing was applied for more than 99% of the science time. During this period several gravitational-wave candidates have been recorded.
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