824 research outputs found
Thermally induced behavior of the K-exchanged erionite. A further step in understanding the structural modifications of the erionite group upon heating
Fibrous erionite is a naturally occurring zeolite considered to be highly carcinogenic upon inhalation, even more than crocidolite. Since no iron is typically present in erionite, its toxicity has been attributed to ion-exchanged Fe participating in Fenton chemistry. Recently, a study aimed at investigating possible fiber inactivation routes surprisingly showed that, despite having completely occluded all available pores with K ions, the erionite-Na sample preserved the property to upload Fe (II) within the structure. In this work, the thermal behavior of the K-exchanged erionite-Na was investigated by TG/ DSC and in situ XRPD analyses in order to provide relevant information for modeling the thermally induced behavior of the erionite group. Rietveld refinement results evidenced a general trend of cell parameters and volume with temperature similar to that observed for erionite-K from Rome (Oregon, USA). However, the dependence of Tdehydrand Tbreakfrom Si/Si+Al ratio observed in zeolites (high Si content favours a lower Tdehydrand a higher Tbreak) is not observed, possibly due to the effect of the relevant amount of large K ions dispersed within the erionite cage, acting as reinforcing blocks for the framework. Heating produces a progressive emptying of the Ca sites, common effect previously observed in erionite samples showing different chemistry. In addition, K1 s.s. remains unchanged evidencing the absence of any “internal ion exchange” process, whereas s.s. at K2 increases in the range 438-573 K and then slowly decreases in the range 700-1218 K. Both Rietveld and DSC data suggest the motion of K ions from OW sites toward the walls of the erionite cavity during dehydration
Advances in Nanomaterials Based on Cashew Nut Shell Liquid
Cashew nut shell liquid (CNSL), obtained as a byproduct of the cashew industry, represents an important natural source of phenolic compounds, with important environmental benefits due to the large availability and low cost of the unique renewable starting material, that can be used as an alternative to synthetic substances in many industrial applications. The peculiarity of the functional groups of CNSL components, such as phenolic hydroxyl, the aromatic ring, acid functionality, and unsaturation(s) in the C15 alkyl side chain, permitted the design of interesting nanostructures. Cardanol (CA), anacardic acid (AA), and cardol (CD), opportunely isolated from CNSL, served as building blocks for generating an amazing class of nanomaterials with chemical, physical, and morphological properties that can be tuned in view of their applications, particularly focused on their bioactive properties
Experimental and theoretical evaluations on Oleuropein as a natural origin corrosion inhibitor for copper in acidic environment
none5siCopper corrosion in acidic cleaning solutions is a major worry for heat exchangers. Corrosion inhibitors derived from natural sources might be a viable option. The isolation of Oleuropein compound from olive leaf and investigation of its anticorrosion potential for copper in 1.0 M H2SO4 solution are reported here. All experimental results from LC-MS, FT-IR, 1H and 13C-NMR characterizations support the molecular structure of Oleuropein. Electrochemical and gravimetric tests were used to evaluate the corrosion inhibition capabilities of Oleuropein. According to polarization investigation, Oleuropein is a mixed-type inhibitor. Oleuropein's inhibitory efficacy increases with concentration, attaining an optimum value (98.92%) at 100 mg L-1. At high temperatures, Oleuropein can be considered an efficient inhibitor. Thermodynamic variables for the activation operation and copper dissolution were computed and addressed as well. Scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) examinations revealed that Oleuropein produced an outer layer on the copper surface, shielding it from severe acid damage. Quantum chemical simulations were employed to propose molecular explanations for Oleuropein's inhibitory actions.Deyab, M A; Mohsen, Q; Bloise, E; Lazzoi, M R; Mele, GDeyab, M A; Mohsen, Q; Bloise, E; Lazzoi, M R; Mele,
Provenance of white marbles from the Roman City of tauriana (Palmi, Reggio Calabria, Italy)
The work shows the results of an archaeometric study performed on fourteen white marble samples from the Roman city of Tauriana (Palmi, Reggio Calabria, Italy), belonging to different architectural elements of the Municipal Museum Complex and artifacts reused in the modern town. Samples were studied by optical microscopy (OM), x-ray powder diffraction (XRPD), and isotope ratio mass spectrometry (IRMS) of13C and18O with the aim to identify their provenance. The comparison between the collected data and the historical ones, concerning the ancient quarries of white marble of the Mediterranean area, allowed us to prove that most of the marbles used in the city of Tauriana were from the Apuan Alps Basin (Carrara) and, in few cases, from Minor Asia (Proconnesos, Aphrodisias, Docimium) and Greek (Thasos and Pentelic) quarries
Avaliação da fertilidade dos solos do Distrito Federal.
O SNLCS tem procurado ampliar o alcance e a utilização prática, dos dados obtidos através dos levantamentos de solos que realiza. Prosseguindo as pesquisas que objetivam a elaboração do mapa de solos do Brasil a nível de reconhecimento, esta entidade vem complementando seus trabalhos com mapas de aptidão agrícola das terras, em relação com diferentes tipos de manejo e culturas. Dentro dos parâmetros usados para definir a aptidão agrícola dos solos, a fertilidade e o mais facilmente controlável e aquele cuja alteração modifica mais sensivelmente a produtividade das terras. Por outro lado, os mapas de aptidão, pela sua natureza, não mostram claramente as limitações de uso devido unicamente ao nível de fertilidade das terras. Tal informação é de grande importância ao estudo de viabilidade econômica de projetos agropecuários, por permitir estimar a necessidade de fertilizantes e corretivos para determinada área. A análise conjunta dos mapas de classificação e aptidão agrícola e ainda de uma avaliação da fertilidade dos solos, daria aos usuários dos trabalhos de levantamento uma visão mais completa dos recursos disponíveis, facilitando as decisões quanto ao tipo de exploração agrícola e ao sistema de manejo mais adequado em cada caso. O presente projeto propõe a complementação de cada trabalho de levantamento com uma avaliação e quantificação da fertilidade, cuja precisão e confiabilidade serão tanto maiores quanto maior for o nível de detalhe do levantamento de solos em que seja baseado.bitstream/item/62835/1/CNPS-BOL.-TEC.-74-80.pdf; bitstream/item/125962/1/Avaliacao-da-Fertilidade-dos-Solos-do-Distrito-Federal.pdfAcompanha 1 mapa, color. Escala 1:100.000
First evidence of wulfenite in Calabria Region (Southern Italy)
This data article contains mineralogical and chemical data of the wulfenite (PbMoO4) sampled from mine of Fiumarella in Calabria region (Southern Italy). Wulfenite is a rare mineral belonging to the class of minerals called molybdates and if found in large amounts it can be used for the extraction of molybdenum. In the mine of Fiumarella, in addition to primary minerals such as barite, galena, cerussite, anglesite, fluorite and chalcopyrite, wulfenite was also detected. Wulfenite crystals are bipyramidal, few microns in size and grow as single crystals that can reach 1 mm. Methods for obtaining the data sets include optical microscopy, micro X-Ray Fluorescence and micro-Raman spectroscopy
Altered umbilical cord blood nutrient levels, placental cell turnover and transporter expression in human term pregnancies conceived by intracytoplasmic sperm injection (Icsi)
Assisted reproductive technologies (ART) may increase risk for abnormal placental development, preterm delivery and low birthweight. We investigated placental morphology, transporter expression and paired maternal/umbilical fasting blood nutrient levels in human term pregnancies conceived naturally (n = 10) or by intracytoplasmic sperm injection (ICSI; n = 11). Maternal and umbilical vein blood from singleton term (>37 weeks) C-section pregnancies were assessed for levels of free amino acids, glucose, free fatty acids (FFA), cholesterol, high density lipoprotein (HDL), low density lipoprotein (LDL), very low-density lipoprotein (VLDL) and triglycerides. We quantified placental expression of GLUT1 (glucose), SNAT2 (amino acids), P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP) (drug) transporters, and placental morphology and pathology. Following ICSI, placental SNAT2 protein expression was downregulated and umbilical cord blood levels of citrulline were increased, while FFA levels were decreased at term (p < 0.05). Placental proliferation and apoptotic rates were increased in ICSI placentae (p < 0.05). No changes in maternal blood nutrient levels, placental GLUT1, P-gp and BCRP expression, or placental histopathology were observed. In term pregnancies, ICSI impairs placental SNAT2 transporter expression and cell turnover, and alters umbilical vein levels of specific nutrients without changing placental morphology. These may represent mechanisms through which ICSI impacts pregnancy outcomes and programs disease risk trajectories in offspring across the life course
Adenomesenteritis following sars-cov-2 vaccination in children. a case report and review of the literature
At present, the vaccine authorized in children aged 5 years and older is the BNT162b2 messenger RNA COVID-19 vaccine. Unlike adults, there is limited data available in the pediatric age describing adverse events after vaccine. We report a case of adenomesenteritis in a young girl following the first dose of vaccine
Atmospheric pressure non-equilibriumplasma for the production of composite materials
In the evolving field of tissue engineering, continuous advances are required
to improve scaffold design and fabrication to obtain biomimetic supports for
cell adhesion, proliferation, penetration and differentiation. Both electrospun
fibrous scaffolds and hydrogels are used in this field since they well
reproduce the structure of the extracellular matrix (ECM) of many biological
tissues. Limitations of these two types of materials can be overcome
through their combination, by developing composite structures combining
enhanced mechanical properties (provided by the fibrous components) and
improved cell penetration (provided by the gel phase) in a superior ability to
mimic natural ECM that is constituted by both a fibrous protein network and
a hydrogel matrix. Here we develop new composite materials made of
electrospun PLLA scaffolds and poly(amidoamine) hydrogels with different
degrees of crosslinking. To promote compatibilization and good adhesion
between the two materials, surface chemical reactions between hydrogels
and PLLA mats are induced by inserting amino functional groups on
electrospun PLLA mats by means of atmospheric pressure non-thermal
plasma. Results will be presented concerning the exposure of PLLA
substrates to the plasma region generated by a Dielectric Barrier Discharge
at atmospheric pressure, driven by a HV Amplifier connected to a function
generator operating with a microsecond rise time and operated in N2.
Surface and solid-state thermo-mechanical characterizations of plasma
treated substrates and of resulting composite materials at different
crosslinking degrees are presented. Results of mechanical tests show a high
adhesion between hydrogel and plasma treated PLLA electrospun mats,
underlining the opportunity to use atmospheric non-thermal plasmas to
fabricate a composite starting from two materials otherwise physically
incompatible. Potential effects of nanofibrous-hydrogel were evaluated by
investigating pluripotent stem cells response
Archaeometric approach for studying architectural earthenwares from the archaeological site of s. Omobono (Rome-Italy)
This paper reports the findings of an archaeometric study performed on 14 architectural earthenwares from the archaeological site of S. Omobono, located in the historic center of Rome (Italy). The archaeological site, accidentally discovered in 1937, includes the remains of a sacred area previously occupied by two temples, one of which was converted into the church of S. Omobono, in 1575. The samples, dated between the 7th and the 6th century BC, belong to different sectors of the site. Their petrographic, mineralogical and geochemical characterization was performed by optical microscopy (OM), X-ray powder diffraction (XRPD), X-ray fluorescence (XRF), electron probe micro-analysis (EPMA), and Raman spectroscopy (RS). The compositional data obtained were also subjected to the principal component analysis (PCA) in order to highlight similarities and differences among the samples. By combining geochemical and petrographic data, we were able to identify several different fabrics. Furthermore, the study provided valuable information on the firing temperatures of some samples and the provenance of the raw materials, by analyzing the chemical composition of clinopyroxenes present as non-plastic inclusions. View Full-Tex
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