Microwave heating of ceramic composites

The microwave heating of a ceramic composite is modelled and analysed. The composite consists of many small ceramic particles embedded in a ceramic cement. The composite is assumed to be well insulated, and each particle is assumed to be in imperfect thermal contact with the surrounding cement. Based on these two assumptions an asymptotic theory exploiting the small Blot number and small non-dimensional contact conductance is developed. Our asymptotic theory yields a set of nonlinear partial differential equations which govern the temperature in the composite. These are reduced to a set of coupled nonlinear ordinary differential equations in which the surface area of each particle enters as a parameter. Recent experiments with such composites have shown that the steady-state temperature of the composite is strongly dependent upon the radii of the embedded particles. Our model captures this effect. In fact, our analysis shows that the assumption of imperfect thermal contact between the particles and the ceramic cement is essential for this trend to be established

A multiscale derivation of a new parabolic equation which includes density variations

AbstractA new parabolic equation is obtained from the acoustic equation by the multiscale method. The new equation incorporates the effects of a variable ocean density. The density can be smooth or piecewise smooth. Thus, the new formulation alleviates the need for interfacial conditions when the density is stratified in a piecewise constant fashion. It also reduces to the standard P.E. when the density is constant. The new equation has the same conservation law as the P.E. A difference equation is presented which has a discrete version of the same law

An Illustrative Model Describing the Refraction of Long Water Waves by a Circular Island

The refraction of small shallow water waves by an idealized island is studied in this paper. The island\u27s shoal is modeled by a quartic polynomial in the radial variable. This particular model allows the explicit construction of the rays (wave orthogonals) and the determination of several important features of the wave motion. The various shortcomings of the particular profile are discussed

Einfluss von Zyklonen auf das Meereis in der zentralen Arktis: Modellstudien und Beobachtungen (Impact of cyclones on sea ice in the central Arctic: model studies and observations)

Arctic sea-ice is a barrier between ocean and atmosphere and as such, plays an important role in the climate system. In winter, a closed ice cover reduces the sensible and latent heat fluxes between ocean and atmosphere to a great extent. In summer, the sea ice reflects the most part of the incoming shortwave radiation. Strong winds, as they occure in cyclones, lead to sea-ice drift and influence the fraction of ocean surface which is covered by sea ice. This study investigates the impact of cyclones on sea ice, with a focus an the sea-ice concentration in the central Arctic. The impact of cyclones is analyzed on the basis of observations of the field campaigns DAMOCLES 2007 and DAMOCLES 2008, on the basis of satellite measurements (AMSR-E ice concentrations) and furthermore on the basis of simulations with a coupled sea-ice-ocean model. For the simulations the dynamic-thermodynamic model NAOSIM (North Atlantic Arctic Ocean Sea Ice Model) is forced with 6-hourly ECMWF-analyses (European Centre for Medium- Range Weather Forecasts). The comparison of simulated ice drift and concentration with observations made clear that the choosen model configuration is appropriate for the performed studies. Sensitivity studies were performed with a wind field that represents a cyclone passing through the Arctic. The experiments show, that the ice concentration is reduced in general under the influence of a cyclone. The reduction is the stronger, (1) the slower the cyclone, (2) the higher the pressure difference between core and surrounding, (3) the smaller the deviation angle between 10 m-wind and geostrophic wind, and (4) the higher the initial ice concentration is. Between reduction of ice concentration and initial ice thickness no correlation has been found. The comparison of simulated ice drift with data of drift buoys reveals, that the model overestimates the drift speed in general whereas extreme events like storms are unterestimated. A systematic deviation in simulated and observed drift direction is found. Furthermore it is shown, in which region the agreement between simulated and messuared ice drift is high and in which regions it is low. In Winter, the model simulates realistic ice concentrations and realistic ice extent. In summer, the ice concentration is too low and the ice extent is too large. A new approach has been made in this study: for a statistical analyses of the impact of a large number of real cyclones on simulated sea ice, 6-hourly positions of cyclones on the basis of the ECMWF sea level pressure field are used. It is investigated how the ice drift, ice concentration and the windfactor are changing at the cyclone’s positions. These investigations include the intensity of the cyclones, the initial ice conditions, the seasonal variability and regional distribution. In summer there is an important climatologic impact of cyclone due to the reduced albedo of a reduced ice cover. Thus, the absorption of solar radiation is increased until the next freezing period. In summer, an increase of cyclone activity accelerates the reduction of the arctic ice concentration

SCATTERING BY PENETRABLE ACOUSTIC TARGETS

An acoustic target of constant density pt and variable index of refraction is imbedded in a surrounding acoustic fluid of constant density pa. A time harmonic wave propagating in the surrounding fluid is incident on the target. We consider two limiting cases of the target where the parameter e = pa/p, + 0 (the nearly rigid target) or E + ~0 (the nearly soft target). When the frequency of the incident wave is bounded away from the 'in-vacua' resonant frequencies of the target, the resulting scattered field is essentially the field scattered by the rigid target for E = 0 or the soft target if E + a). However, when the frequency of the incident wave is near a resonant frequency, the target oscillates and its interaction with the surrounding fluid produces peaks in the scattered field amplitude. In this paper we obtain asymptotic expansions of the solutions of the scattering problems for the nearly rigid and the nearly soft targets as E + 0 or E + co, respectively, that are uniformly valid in the incident frequency. The method of matched asymptotic expansions is used in the analysis. The outer and inner expansions correspond to the incident frequencies being far or near to the resonant frequencies, respectively. We have applied the method only to simple resonant frequencies, but it can be extended to multiple resonant frequencies. The method is applied to the incidence of a plane wave on a nearly rigid sphere of constant index of refraction. The far field expressions for the scattered fields, including the total scattering cross-sections, that are obtained from the asymptotic method and from the partial wave expansion of the solution are in close agreement for sufficiently small values of E

Tetra­potassium dianti­mony(III) tin(IV) tetra­deca­fluoride

The title compound, K4Sb2SnF14, is built from anionic layers, with an overall composition of [Sb2SnF14]4− extending parallel to the ac plane, and K+ cations. The layers are made up from vertex-sharing centrosymmetric SnF6 octa­hedra and Sb2F12 dimers. The Sn—F distances are in the range 1.9581 (14)–1.9611 (17) Å. The Sb polyhedra contain three short terminal Sb—F bonds [1.9380 (14)–2.0696 (15) Å], one short bridging bond [2.0609 (17) Å], one bridging bond of medium length [2.7516 (15) Å], and two longer bridging bonds [3.0471 (18) and 3.117 (2) Å]. The K+ ions are coordinated by F atoms with coordination numbers 10 and 8, and K—F bond lengths are in the range 2.6235 (16)–3.122 (2) Å

Canonical NF-κB promotes lung epithelial cell tumour growth by downregulating the metastasis suppressor CD82 and enhancing epithelial-to-mesenchymal cell transition

Copyright: © 2021 by the authors. Background: The development of non-small cell lung cancer (NSCLC) involves the progressive accumulation of genetic and epigenetic changes. These include somatic oncogenic KRAS and EGFR mutations and inactivating TP53 tumour suppressor mutations, leading to activation of canonical NF-κB. However, the mechanism(s) by which canonical NF-κB contributes to NSCLC is still under investigation. Methods: Human NSCLC cells were used to knock-down RelA/p65 (RelA/p65KD) and investigate its impact on cell growth, and its mechanism of action by employing RNA-seq analysis, qPCR, immunoblotting, immunohistochemistry, immunofluorescence and functional assays. Results: RelA/p65KD reduced the proliferation and tumour growth of human NSCLC cells grown in vivo as xenografts in immune-compromised mice. RNA-seq analysis identified canonical NF-κB targets mediating its tumour promoting function. RelA/p65KD resulted in the upregulation of the metastasis suppressor CD82/KAI1/TSPAN27 and downregulation of the proto-oncogene ROS1, and LGR6 involved in Wnt/β-catenin signalling. Immunohistochemical and bioinformatics analysis of human NSCLC samples showed that CD82 loss correlated with malignancy. RelA/p65KD suppressed cell migration and epithelial-to-mesenchymal cell transition (EMT), mediated, in part, by CD82/KAI1, through integrin-mediated signalling involving the mitogenic ERK, Akt1 and Rac1 proteins. Conclusions: Canonical NF-κB signalling promotes NSCLC, in part, by downregulating the metastasis suppressor CD82/KAI1 which inhibits cell migration, EMT and tumour growth.Institutional Program Grant for the Development of Research Institutes “Advanced research activities in biomedical and agro-alimentary technologies, ARABAT (BITAD)” (MIS5002469) of the operational program “Competitiveness, Entrepreneurship and Innovation” (NSRF2014-20, EU-ERDF); research grant in Biomedical Sciences from FONDATION SANTÉ; STAVROS NIARCHOS Foundation-FORTH Fellowship for PhD candidates of the program ARCHERS: Advancing young researchers’ human capital in cutting edge technologies in the preservation of cultural heritage and the tackling of societal challenges; Biomedical Research Division, IMBB-FORTH; University of Ioannina Research Committee

Drug-microenvironment perturbations reveal resistance mechanisms and prognostic subgroups in CLL

The tumour microenvironment and genetic alterations collectively influence drug efficacy in cancer, but current evidence is limited and systematic analyses are lacking. Using chronic lymphocytic leukaemia (CLL) as a model disease, we investigated the influence of 17 microenvironmental stimuli on 12 drugs in 192 genetically characterised patient samples. Based on microenvironmental response, we identified four subgroups with distinct clinical outcomes beyond known prognostic markers. Response to multiple microenvironmental stimuli was amplified in trisomy 12 samples. Trisomy 12 was associated with a distinct epigenetic signature. Bromodomain inhibition reversed this epigenetic profile and could be used to target microenvironmental signalling in trisomy 12 CLL. We quantified the impact of microenvironmental stimuli on drug response and their dependence on genetic alterations, identifying interleukin 4 (IL4) and Toll-like receptor (TLR) stimulation as the strongest actuators of drug resistance. IL4 and TLR signalling activity was increased in CLL-infiltrated lymph nodes compared with healthy samples. High IL4 activity correlated with faster disease progression. The publicly available dataset can facilitate the investigation of cell-extrinsic mechanisms of drug resistance and disease progression

Germline genetic variants of the renin-angiotensin system, hypoxia and angiogenesis in non-small cell lung cancer progression: Discovery and validation studies

Introduction: The renin–angiotensin system (RAS) is involved in cell proliferation, immunoinflammatory response, hypoxia and angiogenesis, which are critical biological processes in lung cancer. Our aim was to study the association of putatively functional genetic polymorphisms in genes coding for proteins involved in RAS, hypoxia and angiogenesis with non-small cell lung cancer (NSCLC) prognosis. Methods: Genotyping of 52 germline variants from genes of the RAS and hypoxic/angiogenic factors/receptors was performed using MassARRAY iPLEX Gold in a retrospective cohort (n = 167) of advanced NSCLC patients. Validation of the resulting genetic markers was conducted in an independent group (n = 190), matched by clinicopathological characteristics. Results: Multivariate analysis on the discovery set revealed that MME rs701109 C carriers were protected from disease progression in comparison with homozygous T (hazard ratio (HR) = 0.5, 95% confidence interval (CI) = 0.2–0.8, p = 0.010). Homozygous A and T genotypes for KDR rs1870377 were at increased risk for disease progression and death compared to heterozygous (HR = 1.7, 95% CI = 1.2–2.5, p = 0.005 and HR = 2.1, 95% CI = 1.2–3.4, p = 0.006, respectively). Carriers of homozygous genotypes for ACE2 rs908004 presented increased risk for disease progression, only in the subgroup of patients without tumour actionable driver mutations (HR = 2.9, 95% CI = 1.3–6.3, p = 0.010). Importantly, the association of homozygous genotypes in MME rs701109 with risk for disease progression was confirmed after multivariate analysis in the validation set. Conclusion: This study provides evidence that MME polymorphism, which encodes neprilysin, may modulate progression-free survival in advanced NSCLC. Present genetic variation findings will foster basic, translational, and clinical research on their role in NSCLC.M.J.C. was supported by the Associação de Estudos Respiratórios and the Portuguese Pulmonology Society

Lung Adenocarcinoma Cell Sensitivity to Chemotherapies: A Spotlight on Lipid Droplets and SREBF1 Gene

To explore the relationship between cancer cell SREBF1 expression, lipid droplets (LDs) formation, and the sensitivity to chemotherapies, we cultured lung adenocarcinoma cells H1299 (with LD) and H1563 (without LD) in a serum-free basal medium (BM) or neutrophil degranulation products containing medium (NDM), and tested cell responses to cisplatin and etoposide. By using the DESeq2 Bioconductor package, we detected 674 differentially expressed genes (DEGs) associated with NDM/BM differences between two cell lines, many of these genes were associated with the regulation of sterol and cholesterol biosynthesis processes. Specifically, SREBF1 markedly declined in both cell lines cultured in NDM or when treated with chemotherapeutics. Despite the latter, H1563 exhibited LD formation and resistance to etoposide, but not to cisplatin. Although H1299 cells preserved LDs, these cells were similarly sensitive to both drugs. In a cohort of 292 patients with non-small-cell lung cancer, a lower SREBF1 expression in tumors than in adjacent nontumor tissue correlated with overall better survival, specifically in patients with adenocarcinoma at stage I. Our findings imply that a direct correlation between SREBF1 and LD accumulation can be lost due to the changes in cancer cell environment and/or chemotherapy. The role of LDs in lung cancer development and response to therapies remains to be examined in more detail.The study was supported by German Center for Lung Research, grants number 82DZL002B1 (Janciauskiene) and 82DZL00402 (Schneider).S