192 research outputs found
Percutaneous screw fixation for trapezium fracture
Isolated trapezial fracture is a rare diagnosis which can lead to long term symptoms if missed. We report a case of vertical intra-articular displaced trapezial fracture treated with percutaneous cancellous screw fixation with good functional outcome
Protein materials as sustainable non- and minimally invasive strategies for biomedical applications
Protein-based materials have found applications in a wide range of biomedical fields because of their biocompatibility, biodegradability and great versatility. Materials of different physical forms including particles, hydrogels, films, fibers and microneedles have been fabricated e.g. as carriers for drug delivery, factors to promote wound healing and as structural support for the generation of new tissue. This review aims at providing an overview of the current scientific knowledge on protein-based materials, and selected preclinical and clinical studies will be reviewed in depth as examples of the latest progress within the field of protein-based materials, specifically focusing on non- and minimally invasive strategies mainly for topical application
Thioflavin T triggers \u3b2 amyloid peptide (1-40) fibrils formation.
Introduction
A general characteristic of aggregation is the multiple interaction and cross-feedback among distinct mechanisms
occurring at different hierarchical levels. The comprehension of the different species interconversion during aggregation
is very important since emerging evidences indicate intermediate oligomeric aggregates as primary toxic species. In this
context, A\u3b2 amyloid peptide provides a challenging model for studying aggregation phenomena both for the complexity
of its association process and for the direct implications in Alzheimer\u2019s Disease. Aggregates growth conditions strongly
affect the final morphology, the fibrillar molecular structure as well as the aggregation pathway which is characterized
by the occurrence of multiple transient species.
Methods
The fluorescent dye Thioflavin T (ThT) is widely used to detect amyloid deposits and it is often used in situ to study
aggregation kinetics, under the hypothesis that its presence does not affect the aggregation processes under study. Here
we present an experimental study on A\u3b2(1-40) peptide fibrillation kinetics at pH 7.4. In the observed conditions, A\u3b2(1-
40) undergoes aggregation only if Thioflavin T is present in solution. This phenomenon was analyzed as a function of
temperature, ThT and peptide concentrations in order to explore the underlying fibrillation mechanism. Light scattering,
ThT fluorescence emission, two photon excitation fluorescence microscopy, were used in a kinetic fashion to highlight
different sides and critical phases of the aggregation pathway. Circular Dichroism and FTIR measurements are used to
characterize secondary structure of the aggregates.
Results
The selected approach gives detailed information on the time evolution of A\u3b2(1-40) fibrillation process highlighting
structural changes at molecular level, different aggregate species growth and their morphologies. Our data show that
A\u3b2(1-40) fibrillation process occurs only in the presence of ThT and that the observed aggregation involves at least
three different aggregation mechanisms acting in competition. In the first step, small oligomers, which bind ThT, are
formed via non nucleated polymerization mechanism and represent an activated state for following fibrils growth. This
process appear to be a rate limiting step for two distinct fibril nucleation mechanisms probably affected by an high
degree of spatial heterogeneity.
Conclusions
We demonstrated that in the selected experimental conditions ThT triggers the A\u3b2(1 1240) fibrillation process (D\u2019Amico
et. al 2012). Sterical and chemical properties of ThT molecule may modulate the peptide conformation, with similar
mechanisms to the ones that usually drive the binding of this dye to already formed amyloids. So, the presence of ThT
in solution may change the thermodynamic equilibrium trapping specificmore ordered conformations prone to
supramolecular assembly
Phasor-FLIM analysis of cellulose paper ageing mechanism with carbotrace 680 dye
Ageing of paper is a complex process of great relevance for application purposes because of its widespread use as support for information storage in books and documents, and as common low-cost and green packaging material, to name a few. A key factor in paper ageing is the oxidation of cellulose, a macromolecule of natural origin that constitutes the main chemical component of paper. Such a complex process results in changes in the cellulose polymeric chains in chemical and structural properties. The scope of this work is to explore the effects of oxidation of cellulose as one of the principal mechanisms of ageing of paper using a fluorescence-based approach. To this aim, fluorescence-lifetime imaging microscopy (FLIM) measurements on pure cellulose samples stained using Carbotrace 680 dye were performed, and data were analyzed by phasor approach. The comparison with results from conventional techniques allowed to map paper microstructure as a function of the sample oxidation degree correlating the fluorescence-lifetime changes to cellulose oxidation. A two-step oxidation kinetics that produced specific modification in paper organization was highlighted indicating that FLIM measurements using Carbotrace 680 dye may provide a simple tool to obtain information on the oxidation process also adding spatial information at sub-micrometric scale
Quantum erasure within the Optical Stern-Gerlach Model
In the optical Stern-Gerlach effect the two branches in which the incoming
atomic packet splits up can display interference pattern outside the cavity
when a field measurement is made which erases the which-way information on the
quantum paths the system can follow. On the contrary, the mere possibility to
acquire this information causes a decoherence effect which cancels out the
interference pattern. A phase space analysis is also carried out to investigate
on the negativity of the Wigner function and on the connection between its
covariance matrix and the distinguishability of the quantum paths.Comment: 7 pages, 3 figure
Identification of microplastics using 4-dimethylamino-4′-nitrostilbene solvatochromic fluorescence
In this work, we introduce the use of 4-dimethylamino-4′-nitrostilbene (DANS) fluorescent dye for applications in the detection and analysis of microplastics, an impendent source of pollution made of synthetic organic polymers with a size varying from less than 5 mm to nanometer scale. The use of this dye revealed itself as a versatile, fast and sensitive tool for readily discriminate microplastics in water environment. The experimental evidences herein presented demonstrate that DANS efficiently absorbs into a variety of polymers constituting microplastics, and its solvatochromic properties lead to a positive shift of the fluorescence emission spectrum according to the polarity of the polymers. Therefore, under UV illumination, microplastics glow a specific emission spectrum from blue to red that allows for a straightforward polymer identification. In addition, we show that DANS staining gives access to different detection and analysis strategies based on fluorescence microscopy, from simple epifluorescence fragments visualization, to confocal microscopy and phasor approach for plastic components quantification
Itaconic-Acid-Based Sustainable Poly(ester amide) Resin for Stereolithography
Material science is recognized as a frontrunner in achieving a sustainable future, owing to its primary reliance upon petroleum-based chemical raw materials. Several efforts are made to implement common renewable feedstocks as an alternative to common fossil resources. For this purpose, additive manufacturing (AM) represents promising and effective know-how for the replacement of high energy- and resource-demanding processes with more environmentally friendly practices. This work presents a novel biobased ink for stereolithography, which has been formulated by mixing a photocurable poly(ester amide) (PEA) obtained from renewable resources with citrate and itaconate cross-linkers and appropriate photopolymerization initiators, terminators, and dyes. The mechanical features and the relative biocompatibility of 3D-printed objects have been carefully studied to evaluate the possible resin implementation in the field of the textile fashion industry
Implementation of sample pooling procedure using a rapid sars-cov-2 diagnostic real-time pcr test performed prior to hospital admission of people with intellectual disabilities
Reliability, accuracy, and timeliness of diagnostic testing for SARS-CoV-2 infection have allowed adequate public health management of the disease, thus notably helping the timely mapping of viral spread within the community. Furthermore, the most vulnerable populations, such as people with intellectual disability and dementia, represent a high-risk group across multiple dimensions, including a higher prevalence of pre-existing conditions, lower health maintenance, and a propensity for rapid community spread. This led to an urgent need for reliable in-house rapid testing to be performed prior to hospital admission. In the present study, we describe a pooling procedure in which oropharyngeal and nasopharyngeal swabs for SARS-CoV-2 detection (performed prior to hospital admission using rapid RT-PCR assay) are pooled together at the time of sample collection. Sample pooling (groups of 2–4 samples per tube) allowed us to significantly reduce response times, consumables, and personnel costs while maintaining the same test sensitivity
Spatial Orientation And Distribution Of Reservoir Fractures From Scattered Seismic Energy
Shortened title: Fracture characterization from coda wavesWe present the details of a new method for determining the reflection and scattering characteristics of seismic energy from subsurface fractured formations. The method is based upon observations we have made from 3D finite difference modeling of the reflected and scattered seismic energy over discrete systems of vertical fractures. Regularly spaced, discrete vertical fractures impart a ringing coda type signature to any seismic energy which is transmitted through or reflected off of them. This signature varies in amplitude and coherence as a function of several parameters including: 1) the difference in angle between the orientation of the fractures and the acquisition direction, 2) the fracture spacing, 3) the wavelength of the illuminating seismic energy, and 4) the compliance, or stiffness, of the fractures. This coda energy is the most coherent when the acquisition direction is parallel to the strike of the fractures. It has the largest amplitude when the seismic wavelengths are tuned to the fracture spacing, and when the fractures have low stiffness. Our method uses surface seismic reflection traces to derive a transfer function which quantifies the change in an apparent source wavelet before and after propagating through a fractured interval. The transfer function for an interval with no or low amounts of scattering will be more spike-like and temporally compact. The transfer function for an interval with high scattering will ring and be less temporally compact. When a 3D survey is acquired with a full range of azimuths, the variation in the derived transfer functions allows us to identify subsurface areas with high fracturing and determine the strike of those fractures. We calibrated the method with model data and then applied it to the Emilio field with a fractured reservoir giving results which agree with known field measurements and previously published fracture orientations derived from PS anisotropy.Eni S.p.A. (Firm)United States. Dept. of Energy (Grant number DE-FC26-02NT15346)Massachusetts Institute of Technology. Earth Resources Laborator
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