This work aims to evaluate the dynamic performance of a highly selective Ni-based surface during the oxidative dehydrogenation of ethane (ODH-C2). The catalyst comprises an in-house bimetallic ...mixed-oxide formulation with a Ni/Sn atomic ratio of 10. To corroborate its proper synthesis, it is characterized by TGA, AES, XRD, physisorption of N2 and TEM. The catalytic evaluation of the mixed oxide under dynamic conditions allows the proposition of a redox surface mechanism whose reliability is evaluated through a rigorous analysis, which is based on the development of a kinetic model and a robust experimentation program using a fully-automated micro-reaction unit and registering in-situ surface temperatures and continuous inline monitoring of oxygen and carbon dioxide. Experiments are carried out using a mixture of ethane or ethylene, oxygen and nitrogen as feedstock, at temperatures from 360 to 480 °C, total pressures from 100 to 500 kPa, and space-time values from 8.1 to 133.1 kgcat s molC2H6−1. Oxygen conversion ranges from 5% to 100% while the one for ethane varies from 5% to 60%. Besides, the selectivity and yield to ethylene vary from 30% to 90% and from 2% to 40%, respectively. The suitability of the redox mechanism is here assessed by evaluating statistical and phenomenological foundations, including Boudart’s criteria. Kinetic parameters, estimated by non-linear regression and using the reparametrized form of the Arrhenius and van’t Hoff equations, are phenomenologically well founded, such that changes of entropy and enthalpy of adsorption correctly describe the loss of mobility due to adsorption and the exothermic nature of the adsorption processes. Ethylene formation is the reaction demanding the lowest activation energy (Ea1= 61.94 kJ mol−1), while the total oxidation of ethane is the path requiring the largest activation energy (Ea2= 132.6 kJ mol−1). Concerning the adsorption enthalpy, ethylene exhibits the largest value (−ΔHC2H4° = 123.39 kJ mol−1), while carbon dioxide presents the lowest one (−ΔHCO2° = 42.00 kJ mol−1). Additional findings can be summarized as follows: activity and selectivity are recovered after the dynamic operation under oxidative conditions of the catalytic surface; carbon dioxide is identified as the only no desired byproduct; and hydroxyl surface species lead to the formation of water which affects the selectivity to ethylene, as well as the reaction rates. These findings are of interest for future studies directed at elucidating the performance of the Ni-based catalyst at larger scales, paving the way for the efficient design of the industrial reactor for the ODH-C2.
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•A kinetic analysis was performed under dynamic conditions.•A kinetic model was developed by using mathematical and phenomenological grounds.•Activity and selectivity were recovered after the dynamic operation of the surface.•Carbon-based molecules were weakly adsorbed on the catalytic surface.•Hydroxyl surface species affected reaction rates and the selectivity to ethylene.
Vertebral hemangiomas are benign vascular lesions that are almost always incidentally found in the spine. Their classic typical hyperintense appearance on T1- and T2-weighted MR images is diagnostic. ...Unfortunately, not all hemangiomas have the typical appearance, and they can mimic metastases on routine MR imaging. These are generally referred to as atypical hemangiomas and can result in misdiagnosis and ultimately additional imaging, biopsy, and unnecessary costs. Our objective was to assess the utility of dynamic contrast-enhanced MR imaging perfusion in distinguishing vertebral atypical hemangiomas and malignant vertebral metastases. We hypothesized that permeability and vascular density will be increased in metastases compared with atypical hemangiomas.
Consecutive patients from 2011 to 2015 with confirmed diagnoses of atypical hemangiomas and spinal metastases from breast and lung carcinomas with available dynamic contrast-enhanced MR imaging were analyzed. Time-intensity curves were qualitatively compared among the groups. Perfusion parameters, plasma volume, and permeability constant were quantified using an extended Tofts 2-compartment pharmacokinetic model. Statistical significance was tested using the Mann-Whitney
test.
Qualitative inspection of dynamic contrast-enhanced MR imaging time-intensity curves demonstrated differences in signal intensity and morphology between metastases and atypical hemangiomas. Quantitative analysis of plasma volume and permeability constant perfusion parameters showed significantly higher values in metastatic lesions compared with atypical hemangiomas (
< .001).
Our data demonstrate that plasma volume and permeability constant perfusion parameters and qualitative inspection of contrast-enhancement curves can be used to differentiate atypical hemangiomas from vertebral metastatic lesions. This work highlights the benefits of adding perfusion maps to conventional sequences to improve diagnostic accuracy.
The ability of tumor cells to evade the immune system is one of the main challenges we confront in the fight against cancer. Multiple strategies have been developed to counteract this situation, ...including the use of immunostimulant molecules that play a key role in the anti-tumor immune response. Such a response needs to be tumor-specific to cause as little damage as possible to healthy cells and also to track and eliminate disseminated tumor cells. Therefore, the combination of immunostimulant molecules and tumor-associated antigens has been implemented as an anti-tumor therapy strategy to eliminate the main obstacles confronted in conventional therapies. The immunostimulant 4-1BBL belongs to the tumor necrosis factor (TNF) family and it has been widely reported as the most effective member for activating lymphocytes. Hence, we will review the molecular, pre-clinical, and clinical applications in conjunction with tumor-associated antigens in antitumor immunotherapy, as well as the main molecular pathways involved in this association.
The Human Papillomavirus (HPV) is a sexually transmitted infection that significantly affects the population worldwide. HPV preventive methods include vaccination, prophylactics, and education. ...Different types of cancers associated with HPV usually take years or decades to develop after infections, such as Head and Neck Cancer(HNC). Therefore, HPV prevention can be considered cancer prevention. A sample of medical students in Puerto Rico was evaluated to assess their knowledge about HPV, HPV vaccine, and HNC through two previously validated online questionnaires composed of 38 dichotomized questions, we measured HPV, HPV vaccination(HPVK), and HNC knowledge (HNCK). Out of 104 students surveyed, the mean HPVK score obtained was 20.07/26, SD = 3.86, while the mean score for HNCK was 6.37/12, SD = 1.78. Bidirectional stepwise regression showed study year and HPV Vaccine name had been the most influential variables on HPVK and HNCK. MS1 participants scored lower than MS2-MS4 participants, with no significant difference between MS2-MS4 scores. The results reveal knowledge gaps in HPV/HPV Vaccine and HNC among surveyed medical students. Our findings also suggest an association between knowledge of personal vaccination status, self-perceived risk, and how uncertainty in these factors may affect the medical students' understanding of HPV, HPV vaccination, and associated cancers.
This paper analyzes the behavior of Hong's point estimate methods to account for uncertainties on the probabilistic power flow problem. This uncertainty may arise from different sources as load ...demand or generation unit outages. Point estimate methods constitute a remarkable tool to handle stochastic power system problems because good results can be achieved by using the same routines as those corresponding to deterministic problems, while keeping low the computational burden. In previous works related to power systems, only the two-point estimate method has been considered. In this paper, four different Hong's point estimate schemes are presented and tested on the probabilistic power flow problem. Binomial and normal distributions are used to model input random variables. Results for two different case studies, based on the IEEE 14-bus and IEEE 118-bus test systems, respectively, are presented and compared against those obtained from the Monte Carlo simulation. Particularly, this paper shows that the use of the scheme provides the best performance when a high number of random variables, both continuous and discrete, are considered.
This work focuses on the coupling of three different approaches into the same reactor at the same time: microfluidic cells, anodic oxidation with diamond anodes, and an electro-Fenton process. To ...supply oxygen a jet aerator was used and a CB/PTFE Duocel Al foam cathode was installed to promote the formation of hydrogen peroxide. This novel concept is applied for the direct treatment (without the addition of salts or other reagents) of soil washing wastes obtained in the remediation of soil spiked with clopyralid. Results obtained pointed out that this approach can increase the efficiency of the process by folds as compared to traditional treatment technologies. The chemical analysis of the intermediates showed different reaction mechanisms: anodic oxidation, electro-Fenton, and a negligible contribution of coagulation. The coupled systems studied in this work present several advantages such as high treatment efficiency and short treatment time which indicate that the development of electrochemical reactors for diluted liquid wastes is progressing in an adequate direction.
High lactate production in cells during growth under oxygen-rich conditions (aerobic glycolysis) is a hallmark of tumor cells, indicating the role of mitochondrial function in tumorigenesis. In fact, ...enhanced mitochondrial biogenesis and impaired quality control are frequently observed in cancer cells. Mitochondrial DNA (mtDNA) encodes 13 subunits of oxidative phosphorylation (OXPHOS), is present in thousands of copies per cell, and has a very high mutation rate. Mutations in mtDNA and nuclear DNA (nDNA) genes encoding proteins that are important players in mitochondrial biogenesis and function are involved in oncogenic processes. A wide range of germline mtDNA polymorphisms, as well as tumor mtDNA somatic mutations have been identified in diverse cancer types. Approximately 72% of supposed tumor-specific somatic mtDNA mutations reported, have also been found as polymorphisms in the general population. The ATPase 6 and NADH dehydrogenase subunit genes of mtDNA are the most commonly mutated genes in breast cancer (BC). Furthermore, nuclear genes playing a role in mitochondrial biogenesis and function, such as peroxisome proliferators-activated receptor gamma coactivator-1 (PGC-1), fumarate hydratase (FH) and succinate dehydrogenase (SDH) are frequently mutated in cancer. In this review, we provide an overview of the mitochondrial germline variants and mutations in cancer, with particular focus on those found in BC. Abbreviations: mtDNA, mitochondria DNA; BC, breast cancer; OXPHOS, oxidative phosphorylation; NEMtG, nuclear-encoded mitochondrial genes Key words: mitochondria DNA variants, mutations, breast cancer, haplogroups
Diabetic neuropathy (DN) encompasses a group of clinical or subclinical manifestations involving a dysfunction in the peripheral nervous system. The cause of the dysfunction is the development of ...microvascular complications related to diabetes, a disease that affects about 381 million people worldwide. Approximately 50% of patients currently diagnosed with diabetes are expected to manifest DN in the next 10 years. The diagnosis can be made clinically by establishing a good patient history and delving into the symptoms to rule out other etiologies. Treatment of DN focuses on glycemic control and the use of medications to reduce pain, including NSAIDs, antidepressants and antiepileptic drugs. The pathogenesis is of multifactorial origin, associated with various metabolic, vascular, inflammatory and neurodegenerative disorders. The three fundamental cellular alterations participating in the development of DN are chronic inflammation, endothelial dysfunction and oxidative stress. Since the combination of all three is capable of giving rise to nerve ischemia and direct axonal injury, these factors play a key role in the development of polyneuropathy. However, neuronal and microvascular changes do not occur in the same way in all patients with DN, some of whom have no detectable blood abnormalities.
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During the Late Glacial–Early Holocene transition Southern Iberia has an extensive record of Palaeolithic coastal sites, wich have been preserved due thanks to the morphology of the continental ...shelf. This is was a period with rapid palaeoclimatic oscillations and changes in sea level. However, the sites show an apparent continuity in technology and subsistence trends, although human groups made increasingly intense use of marine resources. In this paper we will focus on the study of Mediterranean seal remains from the Vestíbulo hall of Cueva de Nerja (Málaga, Spain), unit NV4, dated 12,990–11,360 cal. BP. The presence of these bones at the site are interpreted as direct exploitation of seals by humans, who processed different parts of the animal like the flesh, blubber and skin. These data allow us to assess the changing role of marine mammals in the regional Palaeolithic economy.
Mathematical models simulating different and representative engineering problem, atomic dry friction, the moving front problems and elastic and solid mechanics are presented in the form of a set of ...non-linear, coupled or not coupled differential equations. For different parameters values that influence the solution, the problem is numerically solved by the network method, which provides all the variables of the problems. Although the model is extremely sensitive to the above parameters, no assumptions are considered as regards the linearization of the variables. The design of the models, which are run on standard electrical circuit simulation software, is explained in detail. The network model results are compared with common numerical methods or experimental data, published in the scientific literature, to show the reliability of the model.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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