169,716 research outputs found
Medical device a partire da materiale biologico
No full textThe development of medical devices presupposes the preliminary identification of the starting biological material, which in this PhD thesis was chosen as bovine pericardium. For its effective clinical application, the bovine pericardium must be decellularized to eliminate the native cells in order to obtain a three-dimensional structure given solely by the proteins constituting the extracellular matrix (ECM). The process designed and developed in Assut Europe S.p.A. consists of a 4-day chemical treatment alternating with washing phases in ultra-purified water to remove any processing residues. The success of the method is demonstrated with DAPI staining and with histological staining with hematoxylin/eosin on sections of native pericardium and on sections of decellularized pericardium, where it was possible to observe, in both cases, the complete absence of residual nuclei and the preservation of the structure of the ECM. The decellularized membranes are compatible with tissue regeneration, in fact they allow progressive cell growth in the first 7 days of culture (for cell viability the NIH3T3 murine fibroblast cell line was used). The decellularization treatment of the membranes also significantly influences the mechanical properties compared to the native tissue, however a significant increase in the value of Young's modulus was highlighted, which expresses the relationship between tension and deformation in the case of uniaxial loading conditions and in case of behavior of the “elastic” material. This value, expressed in MPa, is almost 3 times higher than that of the native membrane, indicating an increase in stiffness (p<0.00001). For its clinical application, bovine pericardial meshes are dehydrated, as the dry version is a highly requested variant on the market, reducing the amount of moisture between 8 and 18%. Starting from the freeze-drying process, we tried to design an “in house” dehydration process using the machinery present in the company to verify the reliability of the method in relation to the nature of the decellularized bovine pericardium. With the use of a blast chiller to freeze the previously decellularized bovine pericardium and an industrial oven connected to a high-performance vacuum pump, it was possible to obtain a dehydrated product with good consistency, which maintained the desired shape, showing a white appearance, with residual humidity between 11 and 15%, rehydratable and resistant to perforation (<1 daN and <5 daN), all parameters that distinguish an excellent quality medical device. The multi-phase processing of the bovine pericardium is characterized by the fact that it is not possible to interrupt production until the finished product is created, however it constitutes a limiting aspect for the company, as sometimes the need arises to create networks of particular shapes and sizes. To evaluate the preservation over time of the decellularized bovine pericardium, they were frozen at a temperature of -18°C in solution N° 5 – boric acid H3BO3 for 90 days. Boric acid is used in the last step of the chemical treatment during the decellularization process of bovine pericardial membranes. After freezing for 90 days, the production processi s resumed until the finished product is created, through the standard procedure that characterizes the medical device. At the same time, processing was carried out with the standard procedure, without interrupting the cycle, until the finished product was created, so as to be able to compare the results. The tests carried out demonstrate how freezing for 90 days in boric acid at a temperature of -18 °C did not alter the required characteristics and preserved collagen properties. Moreover, the samples were evaluated by analyzing the resistance to perforation (burst test >1daN), the thickness (>0.150 mm) and finally the resistance to perforation normalized to the thickness (>5daN) and compared with the pericardis that continued the production process until the creation of the finished product and subjected to the same tests. This experimental work represents part of a broader research and development activity aimed at identifying possible enhancement strategies for existing market products and/or, evaluating alternative processing procedures beyond current practices, with the goal of optimizing re source utilization and minimizing company expense. This work therefore offers insights into the biological/cellular and mechanical properties of a biomaterial obtained from bovine pericardium. This could be of significance for future developments, both for its use as a mesh, also with a view to wider use, especially in the field of biomedical engineering with the development of scaffolds for tissue regeneration
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Fibular nerve palsy after hip replacement: Not only surgeon responsibility. Hereditary neuropathy with liability to pressure palsies (HNPP) a rare cause of nerve liability
No full textMononeuropathy after surgery may occur and hereditary neuropathy with liability to
pressure palsies is a possible pathological condition related to paresis after hip surgery.
We present a case of 66-year-old man presenting severe weakness at inferior limb
muscles after hip prosthesis revision. Clinic and electrophysiology showed severe right
fibular nerve damage and ultrasound found a marked enlargement of the same nerve,
associated with focal enlargements in other nerves. A diagnosis of hereditary neuropathy
with liability to pressure palsies was suspected and confirmed by genetic test. The patient
gradually recovered returning to a normal daily active life. Ultrasound was crucial for
diagnosis. The suspicion and diagnosis of latent neuropathy, which can occur after
surgical intervention, may lead to a better understand of the risks of the surgery, specific
for the patient, and avoid the wrong attribution to surgical malpractice
2‐(Hydroxyimino)aldehydes: photochemical and physico‐chemical properties of a versatile functional group for monomer design
No full textIn the context of our research on stimuli-responsive polymers bearing the 2-(hydroxyimino)aldehyde (HIA) 2 group, we explore the photochemical behavior and physico-chemical properties of a number of HIAs. Interpretation of experimental data is supported by quantum mechanical calculations. HIAs are expected to undergo photoisomerization, chelate metal ions, yield hydrogen-bonded dimers or oligomers, exhibit relatively low pKas, and form >C=NO• radicals through OH hydrogen abstraction or oxidation of the oximate ion. Besides the well-established E/Z oxime photoisomerism, we observe a Norrish-Yang cyclization resulting in cyclobutanol oximes, to our knowledge not described in previous literature. Acidity, Bond Dissociation Enthalpies and electrochemical properties of HIAs are compared to literature data on simple oximes. Results are discussed in relation to the many potential applications for HIAs, with emphasis on the synthesis of novel HIA-containing responsive polymers
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
Classical shadow tomography for continuous variables quantum systems
No full textIn this article we develop a continuous variable (CV) shadow tomography
scheme with wide ranging applications in quantum optics. Our work is motivated
by the increasing experimental and technological relevance of CV systems in
quantum information, quantum communication, quantum sensing, quantum
simulations, quantum computing and error correction. We introduce two
experimentally realisable schemes for obtaining classical shadows of CV
(possibly non-Gaussian) quantum states using only randomised Gaussian unitaries
and easily implementable Gaussian measurements such as homodyne and heterodyne
detection. For both schemes, we show that
samples of an unknown -mode state suffice to learn the expected value
of any -local polynomial in the canonical observables of degree ,
both with high probability and accuracy , as long as the
state has moments of order bounded by . By
simultaneously truncating states and operators in energy and phase space, we
are able to overcome new mathematical challenges that arise due to the
infinite-dimensionality of CV systems. We also provide a scheme to learn
nonlinear functionals of the state, such as entropies over any small number of
modes, by leveraging recent energy-constrained entropic continuity bounds.
Finally, we provide numerical evidence of the efficiency of our protocols in
the case of CV states of relevance in quantum information theory, including
ground states of quadratic Hamiltonians of many-body systems and cat qubit
states. We expect our scheme to provide good recovery in learning relevant
states of 2D materials and photonic crystals
A 0.12mm<sup>2</sup> Wien-Bridge Temperature Sensor with 0.1°C (3σ) Inaccuracy from -40°C to 180°C
No full text Resistor-based temperature sensors can achieve much higher resolution and energy efficiency than conventional BJT-based sensors [1], but they typically occupy more area (> 0.25 mm 2 ) and have lower operating temperatures (le 125 {circ} {C}) [2]-[4]. This work describes a 0.12mm 2 resistor-based sensor that uses a Wien-bridge (WB) filter to achieve 0.1 {circ} {C} (3 sigma) inaccuracy from - 40 {circ} {C} to 180 {circ} {C}. Compared to a state-of-the-art WB sensor [4], it occupies 6 × less area and achieves comparable relative accuracy over a 76% wider operating range. Session 10.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
A ±25A Versatile Shunt-Based Current Sensor with 10kHz Bandwidth and ±0.25% Gain Error from -40°C to 85°C Using 2-Current Calibration
No full textAccurate current sensing is critical in many industrial applications, such as battery management and motor control. Precise shunt-based current sensors have been reported with gain errors of less than 1% over the industrial temperature range (-40°C to 85°C) [1]–[4]. However, since they are intended for coulomb counting, their bandwidth is limited to a few tens of Hz, making them unsuitable for battery impedance or motor-current sensing. This paper presents a current sensor with a wide (10kHz) bandwidth and a tunable temperature compensation scheme (TCS), which allows it to be flexibly used with different types of shunts while maintaining high accuracy. A low-cost room-temperature calibration scheme is proposed to optimize gain flatness over temperature by exploiting the shunt's self-heating at large currents. Over the industrial temperature range and a ±25A current range, it achieves state-of-the-art gain error (±0.25%) with both low-cost PCB and stable metal-alloy shunts.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
- …
