Calcium phosphate is the main mineral phase within our bodies, but despite many studies there is not yet a consensus on how it nucleates. We have used molecular dynamics simulations to investigate ...the interactions of ions in solution and the stability of nanoparticles. At high concentrations, we show that calcium and hydrogen phosphate ions associate to form negatively charged clusters that grow further through a combination of ion attachment and particle-particle interactions. Additional analysis of a cluster of 16 ions at experimental concentrations showed that this is (meta)stable in solution and actually densifies during the simulation. Free energy calculations probing the stability of the nanoparticles further demonstrated that they occupy a free energy minimum lower than the free ions or ion pairs in solution suggesting that calcium phosphate nucleation and growth may occur through the aggregation of small negatively charged clusters.
Using molecular dynamics simulations, we show for the first time that calcium phosphate nanoparticles of eight formula units are thermodynamically stable and could be key in the nucleation of amorphous calcium phosphate.
Amorphous calcium carbonate is often the first phase to precipitate from solution during the mineralization of calcium carbonate, before the formation of one of the crystalline polymorphs. In vivo, ...this phase is believed to be essential for the manufacture of minerals displaying nonequilibrium morphologies. The precipitation of this, usually transient, phase and its subsequent transformation into one of the crystalline polymorphs can be controlled by organic molecules. Here, we present a series of molecular dynamics simulations that explore the amorphous calcium carbonate–water interface, the attachment of amino acids onto both hydrous and anhydrous amorphous calcium carbonate, and their effect on the surface. The results show that surface ions have a different coordination number distribution from bulk ions and can diffuse up to two orders of magnitude faster than their bulk counterparts, suggesting that crystallization is much more likely to occur in this region. All the amino acids investigated bind to the amorphous calcium carbonate surfaces. However, acidic amino acids have a clear preference for the surface of amorphous CaCO3·H2O. The favored mode of interaction of the amino acids is through amine and/or guanidine moieties. The important ramifications of the results for our understanding of protein–mineral interactions are discussed.
The field of terahertz (THz) waveguides continues to grow rapidly, with many being tailored to suit the specific demands of a particular final application. Here, we explore waveguides capable of ...enabling efficient and accurate power delivery within cryogenic environments (< 4 K). The performance of extruded hollow cylindrical metal waveguides made of un-annealed and annealed copper, as well as stainless steel, have been investigated for bore diameters between 1.75 - 4.6 mm, and at frequencies of 2.0, 2.85 and 3.4 THz, provided by a suitable selection of THz quantum cascade lasers. The annealed copper resulted in the lowest transmission losses, < 3 dB/m for a 4.6 mm diameter waveguide, along with 90° bending losses as low as ~2 dB for a bend radius of 15.9 mm. The observed trends in losses were subsequently analyzed and related to measured inner surface roughness parameters. These results provide a foundation for the development of a wide array of demanding low-temperature THz applications, and enabling the study of fundamental physics.
Wound monitoring is essential to tackle chronic complications at their infancy and thus objectively scrutinize any delay in the epithelization process. Since glucose in wound exudates is recognized ...as key bio-marker in wound monitoring, the development of a cost-efficient detection method for glucose would aid at tackling early-stage infections in wounds. For the first time, we present a novel platform for one-step synthesis of non-enzymatic, cost-efficient optical glucose sensors. These are based on complexes formed by the interactions between polyborates and ethanolamines. The complexes, synthesized by just heating a solution of boric acid and ethanolamines at 150 °C, were characterized using
C-NMR,
H-NMR,
B-NMR, analytical ultracentrifugation and DFT. The results show that the complexes in solution are extremely small (hydrodynamic diameter of around 0.5 nm) and that the polyborates species interact with the ethanolamines via both moderate and weak hydrogen bondings. These complexes were then tested on glucose concentrations ranging from 0 to 10 mM, showing significant changes in the fluorescent emission between the glucose level expressed in an healable wound (5.0-7.6 mM) and a chronic one (0.3-1.0 mM).
Engineering a small diameter vascular graft with mechanical and biological properties comparable to living tissues remains challenging. Often, current devices lead to thrombosis and unsatisfactory ...long-term patency as a result of poor blood compatibility and a mismatch between the mechanical properties of the living tissue and the implanted biomaterial. Addressing all these requirements is essential to produce scaffolds able to survive throughout the life of the patient. For this purpose, we fabricated a novel three-layered vascular graft by combining electrospinning and braiding. Mirroring the structure of human blood vessels, the proposed device is composed of three layers: the intima, the media, and the adventitia. The intima and media layers were obtained by sequentially electrospinning silk fibroin (SF) and poly(L-lactide-co- -caprolactone), with ratios selected to match the mechanical properties of the native tissue. For the outer layer, the adventitia, SF yarns were braided on top of the electrospun tubes to create a structure able to withstand high pressures. Compliance, Young's modulus and deformability of the obtained scaffold were similar to that of human blood vessels. Additionally, cytocompatibility of the two layers, media and intima, was assessed in vitro by analysing cell metabolic activity and proliferation of endothelial cells and smooth muscle cells, respectively. Furthermore, heparin functionalization of the scaffolds led to improved anticoagulant properties upon incubation in whole blood. The obtained results indicate a potential application of the herewith designed three-layered construct as a vascular graft for small diameter blood vessel engineering.
Near infrared spectroscopy coupled with chemiometric analysis was investigated as a fast and non destructive method for the identification of wool, cashmere, yak, and angora rabbit fibers in the raw ...and combed sliver state and for the quantitative determination of cashmere in cashmere/wool blends. The main differences among spectra of different animal hair arise from physical charateristics rather than chemical characteristics (mainly pigmentation and mean diameter) of animal fibers. The Soft Independent Modelling by Class Analogy method allows the classification of distinct fibers into separate groups with interclass distances ranging from 12.64 for the nearest classes (white cashmere and wool) to above 1000 for the most distant classes of white and pigmented fibers. Percentages of recognition and rejection of 100 % were found with the exception of a yak sample that was not rejected from the pigmented cashmere class (98 % of rejection). The prediction capacity of the model was also evaluated. Quantitative analysis was carried out using samples obtained by carefully mixing known amounts of wool and white cashmere. A standard error of the estimate of 8.5, a standard error of prediction of 13.10 and a coefficient of determination of 0.95 were calculated. From the results obtained, it can be concluded that near infrared spectroscopy can be used as a tool for an initial and rapid screening of unknown animal fiber samples in the raw and combed sliver states and for a fast and coarse estimate of the amount of cashmere in wool/cashmere blends.
In this work plasma polymerized coatings for anti-pilling purposes were deposited on knitted wool fabrics by means of a capacitively coupled RF discharge reactor using hexamethyldisiloxane as ...precursor. Their resistance to dry and wet cleaning was investigated and compared to that of a wet chemically deposited coating. Different gas mixtures and pre-treatment steps were tested to adjust the plasma process and to improve the film adhesion. An evaluation of the silica-like coatings behaviour to the washing stresses was performed by means of Fourier transform infrared and x-ray photoelectron spectroscopy. Anti-pilling performances of untreated, plasma-treated, and wet chemically treated wool fabrics were assessed.
•Plasma deposited coatings for wool anti-pilling purposes are proposed•Resistance of coatings to washing and dry cleaning stresses was studied•A single step using a HMDSO/Ar/O2 mixture showed the best performance•Anti-pilling properties of wool treated fabrics were significantly improved
Abstract Although it has been suggested that the standardized Ginkgo biloba leaf extract (Egb 761) may have a beneficial effect on memory, the cellular and molecular changes that underlie this ...process are not yet well defined. The present study evaluated the effects of acute (one dose) or subacute treatments (one daily dose/seven days) with EGb 761 (0.5 g kg − 1 and 1.0 g kg − 1 ) on rats submitted to a conditioned emotional response (CER) in comparison with positive (4 mg kg − 1 Diazepam) and negative (12%Tween 80) control groups. To this end, eighty ( n = 10/group) adult, male, Wistar rats (± 250–300 g) were used in an off-baseline CER procedure. We here observed that the rats submitted to an acute and subacute EGb 761 treatments had acquisition of fear conditioning. Additionally, we investigate if the expression of genes previously associated with classical conditioning (CREB-1 and GAP-43) and new candidate genes (GFAP) are modulated following EGb 761 acute treatment. CREB-1, GAP-43 and GFAP mRNA and protein expressions were evaluated using both quantitative PCR (qPCR) and immunohistochemical analysis, respectively. We here show, for the first time, that EGb 761 modulated GAP-43, CREB-1 and GFAP expression in the prefrontal cortex, amygdala and hippocampus. We observed an underexpression of GAP-43 in all structures evaluated and over-expression of GFAP in the amygdala and hippocampus following acute G. biloba treatment when compared to control group (Tween; p < 0.01). GAP-43 expression was decreased in prefrontal cortex and hippocampus in the subacute treatment with EGb 761. Subacute treatment with EGb 761 lead to a decreased CREB-1 in mPFC ( p < 0.001) and increased in the hippocampus to 1.0 g kg − 1 G. biloba group ( p < 0.001). The results obtained from immunohistochemical analysis support our aforementioned findings and revealed that the changes in expression occurred within specific regions in the areas evaluated. All together, our findings not only provide new evidence for a role of EGb 761 on memory but also identify molecular changes that underlie the fear memory consolidation.
Preoperative chemoradiotherapy (CRT) improves the survival of patients with oesophageal cancer when compared with surgery alone.
We conducted a phase II, multicenter trial of FOLFOX-4 and cetuximab ...in patients with locally advanced oesophageal cancer (LAEC) followed by daily radiotherapy (180 cGy fractions to 5040 cGy) with concurrent weekly cetuximab. Cytokines levels potentially related to cetuximab efficacy were assessed using multiplex-bead assays and enzyme-linked immunosorbent assay at baseline, at week 8 and at week 17. Primary end point was complete pathological response rate (pCR).
In all, 41 patients were enroled. Among 30 patients who underwent surgery, a pCR was observed in 8 patients corresponding to a rate of 27%. The most frequent grade 3/4 toxicity was skin (30%) and neutropenia (30%). The 36-month survival rates were 85 and 52% in patients with pathological CR or PR vs 38 and 33% in patients with SD or PD.
Incorporating cetuximab into a preoperative regimen for LAEC is feasible; no correlation between cytokines changes and patient outcome was observed. Positron emission tomography/computed tomography study even if influenced by the small number of patients appears to be able to predict patients outcome both as early and late metabolic response.
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