3,755 research outputs found
Paper-Based Materials for Diagnostics
No full textNowadays point-of care (POC) devices dominate the field of bioanalysis as they play a pivotal role in improving different aspects of diagnostics including screening, early diagnosis, and disease monitoring. These devices comply with the World Health Organization ASSURED criteria that describe the ideal POC tool. While conventional materials like polymers, silicon, metallic foils, and glass have been exploited in POC device manufacturing, recent innovations relying on paper-based materials have introduced a new era of versatile diagnostic tools. Because of their properties, cellulose and its derivatives have emerged as the most common paper-based substrate in device fabrication. The present review explores recent developments in paper-based diagnostics, covering a wide range of applications including reagent storage and isolation/extraction of the analyte and also serving as a sensing platform. The versatility of paper substrates in various diagnostic devices such as lateral flow assays, electrochemical sensors, microfluidics, etc. is discussed, highlighting their advantages, challenges, and limitations on the context of precision medicine
3D Paper-Based Origami Device for Programmable Multifold Analyte Preconcentration
No full textIn analytical chemistry, preconcentration represents a critical step able to enhance the accuracy of detection; however, the experimental procedures needed to preconcentrate samples might be characterized by drawbacks regarding the whole analytical process, e.g., being complex, invasive, and/or time-consuming. In this study, a novel 3D paper-based origami device is introduced for multifold analyte preconcentration. Leveraging the benefits of paper-based substrates, the proposed architecture boosts sample preconcentration while minimizing time and tasks for measurements, solely by exploiting the porous and versatile nature of paper-based substrates. In comparison with other paper-based approaches reported in the literature for preconcentration, the present architecture offers the ability to be programmed for obtaining the needed sensitivity increase without sacrificing measurement time. To demonstrate the efficacy of the novel approach, the 3D paper-based origami device was deeply characterized, including the most relevant parameters, i.e., disk size and number, unfolding time, and volume, and subsequently applied for the preconcentration and the detection of various analytes in real matrices, namely, mercury in tap water and glucose in sweat, resulting in a 400% and 300% sensitivity enhancement, respectively. This innovative preconcentration tool addresses the limitations of existing conventional methods, providing increased sensitivity without the use of expensive and time-consuming procedures through only exploiting the intrinsic properties of paper-based substrates and a rationale design. The proposed architecture emerges as a universal tool to be adopted and programmed for various analytical systems and fields of application
Application of the PRINS technique to titer recombinant virus and evaluation of the efficiency of viral transduction
No full textTitration is an important and critical step in dosing recombinant virus for gene therapy, We present a relatively fast, convenient, and sensitive method that allows for precise quantification of recombinant retrovirus. The method is based on PCR amplification of a foreign gene by the PRINS (primer in situ DNA synthesis) technique, The PRINS technique is based on the sequence-specific annealing of unlabeled oligonucleotide DNA in situ, This oligonucleotide operates as a primer for in situ chain elongation catalyzed by the Tag I polymerase, Using digoxygenin-labeled nucleotides as a substrate for chain elongation, the neo-synthetic DNA is labeled by an FITC-conjugated anti-digoxygenin antibody. To avoid the possibility of false positives, we amplified the puromycin-resistance gene, which is associated with the transgene in the same viral vector and is not normally present in mammalian cells, The retroviral titer was evaluated by counting fluorescein isothiocyanate-positive cells after PRINS labeling, while knowing the number of plated cells that were transduced with different amounts of viral supernatant, A comparable viral concentration of 1 x 10(7) infectious units/mL was found among the retroviruses. (C) 2001 Academic Press
On fractional Hardy-type inequalities in general open sets
No full textWe show that, when sp > N, the sharp Hardy constant hs,p of the punctured space ℝN \ {0} in the Sobolev–Slobodeckiĭ space provides an optimal lower bound for the Hardy constant hs,p(Ω) of an open set Ω ⊂ ℝN. The proof exploits the characterization of Hardy’s inequality in the fractional setting in terms of positive local weak supersolutions of the relevant Euler–Lagrange equation and relies on the construction of suitable supersolutions by means of the distance function from the boundary of Ω. Moreover, we compute the limit of hs,p as s ↗ 1, as well as the limit when p ↗ ∞. Finally, we apply our results to establish a lower bound for the non-local eigenvalue λs,p(Ω) in terms of hs,p when sp > N, which, in turn, gives an improved Cheeger inequality whose constant does not vanish as p ↗ ∞
Geografia degli sport equestri in Italia e nel Lazio: un’analisi introduttiva
No full textLa concentrazione spaziale degli sport equestri e delle attività connesse in Italia è un tema ancora poco esplorato nella geografia dello sport e in quella economica (Helgadóttir e Sigurðardóttir, 2008; Tolls e Carr, 2021). Il contributo si inserisce nel dibattito sugli sport outdoor e sugli “agri-sport” (Ollenburg, 2005), attività in crescita nel periodo post-pandemia (Hedenborg et al., 2024) e con impatti rilevanti (Bale, 2002). Il lavoro analizza la distribuzione delle strutture equestri nel Lazio con un approccio metodologico integrato, che combina analisi quantitative, indagini qualitative e rappresentazioni cartografiche
One-Dimensional Symmetry for the Solutions of a Three-Dimensional Water Wave Problem
No full textWe prove a one-dimensional symmetry result for a weighted Dirichlet-to-Neumann problem arising in a model for water waves in dimension 3. More precisely we prove that minimizers and bounded monotone solutions depend on only one Euclidean variable. The analogue of this result for the 2-dimensional case (and without weights) was established in 16. In this paper a crucial ingredient in the proof is given by an energy estimate for minimizers obtained via a comparison argument
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