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21.
The thermal evolution process of RuO2-SnO2/Ti mixed oxide thin films of varying noble metal content has been investigated by thermogravimetry-mass spectrometry and Fourier transform infrared emission spectroscopy. The gel-like films prepared from aqueous solutions of the precursor salts Sn(OH)2(CH3COO)2−xClx and Ru(OH)Cl3 on titanium metal support were heated in an atmosphere containing 20% O2 and 80% Ar up to 873 K.Chlorine evolution takes place in a single stage process between 573 and 773 K, while the decomposition of organic species like various types of carbonyls, carbonates and carboxylates occurs in two main stages between 423 and 773 K. The combustion temperature of the organic species formed decreases with the increase of the ruthenium content, indicating the catalytic effect of the noble metal. The secondary processes can significantly influence the morphology and electrochemical properties of the films when used as anodes in electrochemical processes. 相似文献
22.
This is the first study to analyze variations in time estimation during 60 h of sleep deprivation and the relation between time estimation performance and the activation measures of skin resistance level, body temperature, and Stanford Sleepiness Scale (SSS) scores. Among 30 healthy participants 18 to 24 years of age, for a 10-s interval using the production method, we found a lengthening in time estimations that was modulated by circadian oscillations. No differences in gender were found in the time estimation task during sleep deprivation. The variations in time estimation correlated significantly with body temperature, skin resistance level, and SSS throughout the sleep deprivation period. When body temperature is elevated, indicating a high level of activation, the interval tends to be underestimated, and vice versa. When the skin resistance level or SSS is elevated (low activation), time estimation is lengthened, and vice versa. This lengthening is important because many everyday situations involve duration estimation under moderate to severe sleep loss. Actual or potential applications of this research include transportation systems, emergency response work, sporting activities, and industrial settings in which accuracy in anticipation or coincidence timing is important for safety or efficiency. 相似文献
23.
During embryogenesis and in the early stages of life, the thymus is a crucial organ for the generation of the T cell repertoire. T cells are generated from hematopoietic stem cells already differentiated to precursor T cells in the bone marrow. These cells enter the thymus guided by chemotactic factors secreted by this organ. The complex maturation process takes place that ensures self-tolerance and homeostasis. Thymocytes that show autoreactivity do not leave the thymus, but rather die by apoptosis. The final percentage of mature T cells that survive to migrate from the thymus to the periphery is very low: at most 5%, under optimal conditions. The highest migration occurs in childhood and adulthood, at least in mice and humans; however, it declines throughout life and is minimal in the elderly. Under normal circumstances, the thymus commences involution soon after birth, and this involution correlates with the capacity to export mature T cells to the periphery. Hormones, cytokines, and neurotransmitters all play a role in this age-associated process, but the reasons for and mechanisms of this involution remain unknown. Apart from physiological conditions that change throughout life and govern age-related thymus evolution, random states and events provoked by intrinsic or extrinsic factors can induce either thymus involution, as in reversible transient thymic hypoplasias, or thymic hyperplasias. The age-associated involution, unlike transient involutions, follows a regular pattern for all individuals, though there are clear differences between the sexes. Nevertheless, even the age-associated involution seems to be reversible, raising the possibility of therapeutic strategies aimed at enhancing thymus function in the elderly. 相似文献
24.
M. Lourdes Borrajo Rosalía Laza Juan M. Corchado 《Applied Artificial Intelligence》2013,27(5):377-406
The complexity of current organization systems, and the increase in the importance of the realization of internal controls in firms, make it necessary to construct models that automate and facilitate the work of auditors. A tool for the decision support process has been developed. The objective of the system is to facilitate the process of internal auditing in small and medium-sized enterprises. The system analyzes the data that characterizes each one of the activities carried out by the firm, then determines the state of each activity, calculates the associated risk, detects the erroneous processes, and generates recommendations to improve these processes. The developed model is composed of two case-based reasoning systems. One is used to identify the activities that may be improved and the other to determine how the activities could be improved. Each of the two subsystems use a different problem-solving method in each of the steps of the reasoning cycle. The system has been tested in 22 small and medium-sized companies in the textile sector, located in the northwest of Spain during the last 38 months and the obtained results are very encouraging. 相似文献
25.
Ravi Garg Anastasios Roussos Lourdes Agapito 《International Journal of Computer Vision》2013,104(3):286-314
This paper addresses the problem of non-rigid video registration, or the computation of optical flow from a reference frame to each of the subsequent images in a sequence, when the camera views deformable objects. We exploit the high correlation between 2D trajectories of different points on the same non-rigid surface by assuming that the displacement of any point throughout the sequence can be expressed in a compact way as a linear combination of a low-rank motion basis. This subspace constraint effectively acts as a trajectory regularization term leading to temporally consistent optical flow. We formulate it as a robust soft constraint within a variational framework by penalizing flow fields that lie outside the low-rank manifold. The resulting energy functional can be decoupled into the optimization of the brightness constancy and spatial regularization terms, leading to an efficient optimization scheme. Additionally, we propose a novel optimization scheme for the case of vector valued images, based on the dualization of the data term. This allows us to extend our approach to deal with colour images which results in significant improvements on the registration results. Finally, we provide a new benchmark dataset, based on motion capture data of a flag waving in the wind, with dense ground truth optical flow for evaluation of multi-frame optical flow algorithms for non-rigid surfaces. Our experiments show that our proposed approach outperforms state of the art optical flow and dense non-rigid registration algorithms. 相似文献
26.
Twitter spam detection is a recent area of research in which most previous works had focused on the identification of malicious user accounts and honeypot-based approaches. However, in this paper we present a methodology based on two new aspects: the detection of spam tweets in isolation and without previous information of the user; and the application of a statistical analysis of language to detect spam in trending topics. Trending topics capture the emerging Internet trends and topics of discussion that are in everybody’s lips. This growing microblogging phenomenon therefore allows spammers to disseminate malicious tweets quickly and massively. In this paper we present the first work that tries to detect spam tweets in real time using language as the primary tool. We first collected and labeled a large dataset with 34 K trending topics and 20 million tweets. Then, we have proposed a reduced set of features hardly manipulated by spammers. In addition, we have developed a machine learning system with some orthogonal features that can be combined with other sets of features with the aim of analyzing emergent characteristics of spam in social networks. We have also conducted an extensive evaluation process that has allowed us to show how our system is able to obtain an F-measure at the same level as the best state-of-the-art systems based on the detection of spam accounts. Thus, our system can be applied to Twitter spam detection in trending topics in real time due mainly to the analysis of tweets instead of user accounts. 相似文献
27.
Marta Gabasa Marselina Arshakyan Alejandro Llorente Lourdes Chuli-Peris Irina Pavelescu Antoni Xaubet Javier Pereda Jordi Alcaraz 《International journal of molecular sciences》2020,21(22)
Pro-inflammatory cytokines like interleukin-1β (IL-1β) are upregulated during early responses to tissue damage and are expected to transiently compromise the mechanical microenvironment. Fibroblasts are key regulators of tissue mechanics in the lungs and other organs. However, the effects of IL-1β on fibroblast mechanics and functions remain unclear. Here we treated human pulmonary fibroblasts from control donors with IL-1β and used Atomic Force Microscopy to unveil that IL-1β significantly reduces the stiffness of fibroblasts concomitantly with a downregulation of filamentous actin (F-actin) and alpha-smooth muscle (α-SMA). Likewise, COL1A1 mRNA was reduced, whereas that of collagenases MMP1 and MMP2 were upregulated, favoring a reduction of type-I collagen. These mechanobiology changes were functionally associated with reduced proliferation and enhanced migration upon IL-1β stimulation, which could facilitate lung repair by drawing fibroblasts to sites of tissue damage. Our observations reveal that IL-1β may reduce local tissue rigidity by acting both intracellularly and extracellularly through the downregulation of fibroblast contractility and type I collagen deposition, respectively. These IL-1β-dependent mechanical effects may enhance lung repair further by locally increasing pulmonary tissue compliance to preserve normal lung distension and function. Moreover, our results support that IL-1β provides innate anti-fibrotic protection that may be relevant during the early stages of lung repair. 相似文献
28.
Yukio Kakuda Firouz Jahaniaval Massimo F. Marcone Lourdes Montevirgen Quintin Montevirgen Joselyn Umali 《Journal of the American Oil Chemists' Society》2000,77(9):991-997
The fatty acid and triacylglycerol composition of pili nut (Canarium ovatum) oil and fractions were analyzed by gas chromatography and reversed-phase high-performance liquid chromatography, respectively.
The oil obtained by solvent extraction was low in polyunsaturated fatty acids and high in saturates. The polyunsaturated fatty
acid (18∶2 and 18∶3) contents were less than 11%, whereas palmitic (16∶0) and stearic acid (18∶0) were 33.3 and 10.9%, respectively.
The saturated fatty acid level of the low-melting fraction oil was reduced from 44.4 to 35.5% and the total unsaturated fatty
acid levels were increased from 55.6 to 65% by fractional crystallization. Triacylglycerol analysis showed that the high-melting
fraction (HM) from pili nut oil consisted of POP, POS, and SOS+SSO (P=palmitic acid, O=oleic acid, and S=stearic acid) in
the proportion of 48.6, 38.8, and 8.7%, respectively. The physicochemical properties of the HM fraction were studied using
differential scanning calorimetry and pulsed nuclear magnetic resonance. The results showed that the melting range and solid
fat content of the HM fraction were very similar to those isolated from cocoa butter and olive oil. The content of POP played
an important role in determining the melting range of the HM fraction. It is suggested that this HM fraction may have applications
as a cocoa butter substitute in confectionery products. 相似文献
29.
Guadalupe Rosario Fajardo-Ordua Edgar Ledesma-Martínez Itzen Aguiiga-Snchez María de Lourdes Mora-García Benny Weiss-Steider Edelmiro Santiago-Osorio 《International journal of molecular sciences》2021,22(9)
Acute myeloid leukemia (AML), the most common type of leukemia in older adults, is a heterogeneous disease that originates from the clonal expansion of undifferentiated hematopoietic progenitor cells. These cells present a remarkable variety of genes and proteins with altered expression and function. Despite significant advances in understanding the molecular panorama of AML and the development of therapies that target mutations, survival has not improved significantly, and the therapy standard is still based on highly toxic chemotherapy, which includes cytarabine (Ara-C) and allogeneic hematopoietic cell transplantation. Approximately 60% of AML patients respond favorably to these treatments and go into complete remission; however, most eventually relapse, develop refractory disease or chemoresistance, and do not survive for more than five years. Therefore, drug resistance that initially occurs in leukemic cells (primary resistance) or that develops during or after treatment (acquired resistance) has become the main obstacle to AML treatment. In this work, the main molecules responsible for generating chemoresistance to Ara-C in AML are discussed, as well as some of the newer strategies to overcome it, such as the inclusion of molecules that can induce synergistic cytotoxicity with Ara-C (MNKI-8e, emodin, metformin and niclosamide), subtoxic concentrations of chemotherapy (PD0332991), and potently antineoplastic treatments that do not damage nonmalignant cells (heteronemin or hydroxyurea + azidothymidine). 相似文献
30.
Francisco Hernndez-Beltrn Juan Carlos Moreno-Mayorga María de Lourdes Guzmn-Castillo Juan Navarrete-Bolaos Montserrat Gonzlez-Gonzlez Brent E. Handy 《Applied Catalysis A: General》2003,240(1-2):41-51
The evolution of the properties of a REUSY zeolite contained in a fluid cracking catalyst was investigated under laboratory steam deactivation procedures and in age fractions of the corresponding equilibrium catalyst (Ecat). The aging pattern, defined by the evolution of the zeolite surface area (ZSA) related to the decrease of the unit cell size (UCS), was similar between lab-steamed zeolites and Ecat fractions. A sharp drop in ZSA occurred at ca. 2.430 nm UCS. A study done by FT-IR spectroscopy suggested that zeolite dealumination initially took place more extensively on the sodalite cages and double six-member rings (D6R) of the structure and that the final collapse of the zeolite framework occurred through destruction of the 12-member rings (12M). This can be explained by a crystal fracture and break down process and disassembling of the sodalite cages in the faujasite structure. NH3 microcalorimetry showed that strong acid sites in faujasites are destroyed by steam aging, but this effect does not lead to a reduction in the cracking activity of the Ecat form. The microactivity test (MAT) showed that the specific activity declined sharply at 2.430 nm UCS. Differences in product selectivity were related to the extent of damage of the zeolite, extra-framework alumina and mesoporosity. While further aging canceled the effect attributed to extra-framework alumina differences attributed to mesoporosity increased. 相似文献