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"M. Cervantes"
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Morphological and Mechanical Properties of Electrospun Polycaprolactone Scaffolds: Effect of Applied Voltage
by
Oliva, A.I.
,
Can-Herrera, L.A.
,
Cervantes-Uc, J.M.
in
Atomic force microscopy
,
Change detection
,
Contact angle
2021
The aim of this work is to investigate the effect of the applied voltage on the morphological and mechanical properties of electrospun polycaprolactone (PCL) scaffolds for potential use in tissue engineering. The morphology of the scaffolds was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), and the BET techniques for measuring the surface area and pore volume. Stress-strain curves from tensile tests were obtained for estimating the mechanical properties. Additional studies for detecting changes in the chemical structure of the electrospun PCL scaffolds by Fourier transform infrared were performed, while contact angle and X-ray diffraction analysis were realized for determining the wettability and crystallinity, respectively. The SEM, AFM and BET results demonstrate that the electrospun PCL fibers exhibit morphological changes with the applied voltage. By increasing the applied voltage (10 to 25 kV) a significate influence was observed on the fiber diameter, surface roughness, and pore volume. In addition, tensile strength, elongation, and elastic modulus increase with the applied voltage, the crystalline structure of the fibers remains constant, and the surface area and wetting of the scaffolds diminish. The morphological and mechanical properties show a clear correlation with the applied voltage and can be of great relevance for tissue engineering.
Journal Article
Effect of a Resistance Training Program on Sarcopenia and Functionality of the Older Adults Living in a Nursing Home
by
Monroy Torres, Rebeca
,
del Campo Cervantes, J. Martín
,
Macías Cervantes, M. Habacuc
in
Aged
,
Aged, 80 and over
,
Aging
2019
There are currently few evidence about resistance training as a treatment for sarcopenia in the nursing home setting.
To evaluate the effect of a resistance training program on the sarcopenia and functionality of the elderly living in a nursing home.
A blinded longitudinal intervention study conducted in elderly people living in a nursing home from August to November 2016. Participants included a convenience sample of 19 older adults.
We prescribed a resistance exercise program three times a week for 12 weeks. The scheme was two to three sets with eight to 15 repetitions per exercise.
The primary outcome was an increase in muscle strength and an improvement in physical performance of the elderly people living in nursing homes.
19 older adults between 77.7 ± 8.9 years old, completed the 12 week resistance exercise program achieving a significant increase in muscle strength to 5.7 Kg (p = 0.0001) as well as nutritional intake for the first four weeks (p = 0.001); we found an improvement in physical performance (p = 0.0001) in balance (p = 0.0001), chair stand (p = 0.036) and gait speed (p = 0.0001). Of the 47.4% that reached sarcopenia degree, in the end it was 33.3%. A relationship with nutritional status (p = 0.004) and age (p = 0.019) was found with the initial and final handgrip strength (p = 0.041).
The resistance training program improves the functionality (muscle strength and physical performance), with the benefit of the decrease in severe sarcopenia.
Journal Article
Flickr30k Entities: Collecting Region-to-Phrase Correspondences for Richer Image-to-Sentence Models
by
Lazebnik, Svetlana
,
Caicedo, Juan C.
,
Hockenmaier, Julia
in
Annotations
,
Artificial Intelligence
,
Automation
2017
The Flickr30k dataset has become a standard benchmark for sentence-based image description. This paper presents Flickr30k Entities, which augments the 158k captions from Flickr30k with 244k coreference chains, linking mentions of the same entities across different captions for the same image, and associating them with 276k manually annotated bounding boxes. Such annotations are essential for continued progress in automatic image description and grounded language understanding. They enable us to define a new benchmark for localization of textual entity mentions in an image. We present a strong baseline for this task that combines an image-text embedding, detectors for common objects, a color classifier, and a bias towards selecting larger objects. While our baseline rivals in accuracy more complex state-of-the-art models, we show that its gains cannot be easily parlayed into improvements on such tasks as image-sentence retrieval, thus underlining the limitations of current methods and the need for further research.
Journal Article
Exposure to Mycobacterium remodels alveolar macrophages and the early innate response to Mycobacterium tuberculosis infection
Alveolar macrophages (AMs) play a critical role during Mycobacterium tuberculosis (Mtb) infection as the first cells in the lung to encounter bacteria. We previously showed that AMs initially respond to Mtb in vivo by mounting a cell-protective, rather than pro-inflammatory response. However, the plasticity of the initial AM response was unknown. Here, we characterize how previous exposure to Mycobacterium , either through subcutaneous vaccination with Mycobacterium bovis (scBCG) or through a contained Mtb infection (coMtb) that mimics aspects of concomitant immunity, impacts the initial response by AMs. We find that both scBCG and coMtb accelerate early innate cell activation and recruitment and generate a stronger pro-inflammatory response to Mtb in vivo by AMs. Within the lung environment, AMs from scBCG vaccinated mice mount a robust interferon-associated response, while AMs from coMtb mice produce a broader inflammatory response that is not dominated by Interferon Stimulated Genes. Using scRNAseq, we identify changes to the frequency and phenotype of airway-resident macrophages following Mycobacterium exposure, with enrichment for both interferon-associated and pro-inflammatory populations of AMs. In contrast, minimal changes were found for airway-resident T cells and dendritic cells after exposures. Ex vivo stimulation of AMs with Pam3Cys, LPS and Mtb reveal that scBCG and coMtb exposures generate stronger interferon-associated responses to LPS and Mtb that are cell-intrinsic changes. However, AM profiles that were unique to each exposure modality following Mtb infection in vivo are dependent on the lung environment and do not emerge following ex vivo stimulation. Overall, our studies reveal significant and durable remodeling of AMs following exposure to Mycobacterium , with evidence for both AM-intrinsic changes and contributions from the altered lung microenvironments. Comparisons between the scBCG and coMtb models highlight the plasticity of AMs in the airway and opportunities to target their function through vaccination or host-directed therapies.
Journal Article
Superconducting nonlinear transport in optically driven high-temperature K3C60
2023
Optically driven quantum materials exhibit a variety of non-equilibrium functional phenomena, which to date have been primarily studied with ultrafast optical, X-Ray and photo-emission spectroscopy. However, little has been done to characterize their transient electrical responses, which are directly associated with the functionality of these materials. Especially interesting are linear and nonlinear current-voltage characteristics at frequencies below 1 THz, which are not easily measured at picosecond temporal resolution. Here, we report on ultrafast transport measurements in photo-excited K
3
C
60
. Thin films of this compound were connected to photo-conductive switches with co-planar waveguides. We observe characteristic nonlinear current-voltage responses, which in these films point to photo-induced granular superconductivity. Although these dynamics are not necessarily identical to those reported for the powder samples studied so far, they provide valuable new information on the nature of the light-induced superconducting-like state above equilibrium T
c
. Furthermore, integration of non-equilibrium superconductivity into optoelectronic platforms may lead to integration in high-speed devices based on this effect.
The authors report ultrafast transport measurements on the photo-excited superconducting state in K
3
C
60
. They observe characteristic superconducting nonlinear current-voltage responses.
Journal Article
Observation of coherent elastic neutrino-nucleus scattering
2017
The coherent elastic scattering of neutrinos off nuclei has eluded detection for four decades, even though its predicted cross section is by far the largest of all low-energy neutrino couplings. This mode of interaction offers new opportunities to study neutrino properties and leads to a miniaturization of detector size, with potential technological applications. We observed this process at a 6.7σ̃ confidence level, using a low-background, 14.6-kilogram CsI[Na] scintillator exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic signatures in energy and time, predicted by the standard model for this process, were observed in high signal-to-background conditions. Improved constraints on nonstandard neutrino interactions with quarks are derived from this initial data set.
Journal Article
Thermal degradation of poly(caprolactone), poly(lactic acid), and poly(hydroxybutyrate) studied by TGA/FTIR and other analytical techniques
by
Vázquez-Torres, H.
,
Herrera-Kao, W. A.
,
Cauich-Rodríguez, J. V.
in
Aldehydes
,
Biopolymers
,
Carbon
2018
Thermal degradation of three biodegradable polyesters: poly(caprolactone), poly(lactic acid), and poly(hydroxybutyrate), was studied by thermogravimetry coupled to Fourier Transform Infrared Spectroscopy TGA/FTIR before and after they were partially degraded. TGA curves and Gram–Schmidt plots showed only one decomposition stage for both poly(caprolactone), PCL, and poly(lactic acid), PLA. In contrast, poly(hydroxybutyrate), PHB, exhibited two degradation stages by TGA, but only one region of evolved gases was appreciated in the Gram–Schmidt plot. It was established that hexenoic acid, ε-caprolactone, and small fragments of polymeric chains are the main degradation products of PCL, which were simultaneously released during thermal decomposition of this polymer. Meanwhile, carboxylic acid, aldehydes, and lactide monomer and/or oligomers were evolved from degradation of PLA. Finally, carboxylic acids and ester moiety were detected in the course of degradation of PHB; thus, random chain scission reaction took place during thermal decomposition of this polymer. Results from the spectroscopic characterization (FTIR and
1
H NMR) of partially degraded samples supported the degradation mechanisms suggested by TGA/FTIR studies.
Journal Article
The XENON1T dark matter experiment
by
Garbini, M.
,
Aprile, E.
,
Sartorelli, G.
in
Astronomy
,
Astrophysics and Cosmology
,
Dark matter
2017
The XENON1T experiment at the Laboratori Nazionali del Gran Sasso (LNGS) is the first WIMP dark matter detector operating with a liquid xenon target mass above the ton-scale. Out of its 3.2 t liquid xenon inventory, 2.0 t constitute the active target of the dual-phase time projection chamber. The scintillation and ionization signals from particle interactions are detected with low-background photomultipliers. This article describes the XENON1T instrument and its subsystems as well as strategies to achieve an unprecedented low background level. First results on the detector response and the performance of the subsystems are also presented.
Journal Article
Prebiotic Potential of Agave angustifolia Haw Fructans with Different Degrees of Polymerization
by
Mendiola, Roberto
,
Aparicio, Antonio
,
Hernández-Gallegos, Minerva
in
Agave - chemistry
,
Agave angustifolia Haw
,
Bacteria
2014
Inulin-type fructans are the most studied prebiotic compounds because of their broad range of health benefits. In particular, plants of the Agave genus are rich in fructans. Agave-derived fructans have a branched structure with both β-(2→1) and β-(2→6) linked fructosyl chains attached to the sucrose start unit with a degree of polymerization (DP) of up to 80 fructose units. The objective of this work was to assess the prebiotic potential of three Agave angustifolia Haw fructan fractions (AFF) with different degrees of polymerization. The three fructan fractions were extracted from the agave stem by lixiviation and then purified by ultrafiltration and ion exchange chromatography: AFF1, AFF2 and AFF3 with high (3–60 fructose units), medium (2–40) and low (2–22) DP, respectively. The fructan profile was determined with high-performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), which confirmed a branched fructan structure. Structural elucidation was performed by Fourier Transform Infra-Red Spectroscopy. The AFF spectrum shows characteristic fructan bands. The prebiotic effect of these fractions was assessed in vitro through fermentation by Bifidobacterium and Lactobacillus strains. Four growth patterns were observed. Some bacteria did not grow with any of the AFF, while other strains grew with only AFF3. Some bacteria grew according to the molecular weight of the AFF and some grew indistinctly with the three fructan fractions.
Journal Article
Cytotoxicity and Chemotaxonomic Significance of Saponins from Wild and Cultured Asparagus Shoots
by
Chileh-Chelh, Tarik
,
Ezzaitouni, Mohamed
,
Guil-Guerrero, José L.
in
Asparagus
,
Asparagus Plant - chemistry
,
Asparagus Plant - classification
2024
The shoots of Asparagus L. are consumed worldwide, although most species belonging to this genus have a restricted range, and several taxa remain unstudied. In this work, a total of four taxa from different locations were scrutinized and compared with cultivated A. officinalis. All shoots were screened for saponins via LC-MS, and in vitro antiproliferative activities against the HT-29 colorectal cancer cell line were assessed via the MTT assay. The total saponins (TS) contained in the crude extracts ranged from 710.0 (A. officinalis) to 1258.6 mg/100 g dw (A. acutifolius). The richness of the compounds detected in this work stands out; a total of 47 saponins have been detected and quantified in the edible parts (shoots) of five taxa of Asparagus. The structure of all the saponins found present skeletons of the furostane and spirostane type. In turn, the structures with a furostane skeleton are divided into unsaturated and dioxygenated types, both in the 20–22 position. The sum of dioscin and derivatives varied largely among the studied taxa, reaching the following percentages of TS: 27.11 (A. officinalis), 18.96 (A. aphyllus), 5.37 (A. acutifolius), and 0.59 (A. albus); while in A. horridus, this compound remains undetected. Aspachiosde A, D, and M varied largely among samples, while a total of seven aspaspirostanosides were characterized in the analyzed species. The hierarchical cluster analysis of the saponin profiles clearly separated the various taxa and demonstrated that the taxonomic position is more important than the place from which the samples were acquired. Thus, saponin profiles have chemotaxonomic significance in Asparagus taxa. The MTT assay showed dose- and time-dependent inhibitory effects of all saponins extracts on HT-29 cancer cells, and the strongest cell growth inhibition was exercised by A. albus and A. acutifolius (GI50 of 125 and 175 µg/mL). This work constitutes a whole approach to evaluating the saponins from the shoots of different Asparagus taxa and provides arguments for using them as functional foods.
Journal Article