2,248 research outputs found
Mixed Finite Elements of Higher-Order in Elastoplasticity
In this paper a higher-order mixed finite element method for elastoplasticity
with linear kinematic hardening is analyzed. Thereby, the non-differentiability
of the involved plasticity functional is resolved by a Lagrange multiplier
leading to a three field formulation. The finite element discretization is
conforming in the displacement field and the plastic strain but potentially
non-conforming in the Lagrange multiplier as its Frobenius norm is only
constrained in a certain set of Gauss quadrature points. A discrete inf-sup
condition with constant 1 and the well posedness of the discrete mixed problem
are shown. Moreover, convergence and guaranteed convergence rates are proved
with respect to the mesh size and the polynomial degree, which are optimal for
the lowest order case. Numerical experiments underline the theoretical results.Comment: 20 page
A Posteriori Error Estimates for -FE Discretizations in Elastoplasticity
In this paper, a reliable a posteriori error estimator for a model problem of
elastoplasticity with linear kinematic hardening is derived, which satisfies
some (local) efficiency estimates. It is applicable to any discretization that
is conforming with respect to the displacement field and the plastic strain.
Furthermore, the paper presents -finite element discretizations relying on
a variational inequality as well as on a mixed variational formulation and
discusses their equivalence by using biorthogonal basis functions. Numerical
experiments demonstrate the applicability of the theoretical findings and
underline the potential of - and -adaptive finite element
discretizations for problems of elastoplasticity.Comment: 20 page
Karte der potentiellen natürlichen Vegetation Deutschlands im Maßstab 1:500.000
Mit dem ersten gemeinsamen Land/Bund-Forschungsvorhaben wurde bereits im Jahr 2000 die sogenannte „Landeskarte“ der Potentiellen Natürlichen Vegetation von Sachsen-Anhalt veröffentlicht mit Erläuterungen zu standörtlichen Verhältnissen, den Vegetationseinheiten und naturnahen Wäldern (LAU 2000). In den nachfolgenden Jahren wurden weitere Bundesländer bearbeitet und zu der nun vorliegenden PNV-Karte von Deutschland im Maßstab 1:500.000 zusammengefasst (BfN 2010)
Synthesis, Characterization And Antitumor Activity Of Copper(II) Complexes, [CuL2] [HL1-3=N,N-Diethyl-N'-(R-Benzoyl)Thiourea (R=H, o-Cl and p-NO2)]
The copper (II) complexes (CuL2) were prepared by reaction of Cu(CH3COO)2 with the corresponding derivatives of acylthioureas in a Cu:HL molar ratio of 1:2. Acylthiourea ligands, N,N-diethyl-N'-(R-benzoyl)
thiourea (HL1-3) [R=H, o-Cl and p-NO2] were synthesized in high yield (78-83%) and characterized
by elemental analysis, infrared spectroscopy, 1H and 13C NMR spectroscopy. The complexes CuL2 were
characterized by elemental analysis, IR, FAB(+)-MS, magnetic susceptibility measurements, EPR and cyclic
voltammetry. The crystal structure of the complex Cu(L2)2 shows a nearly square-planar geometry with two
deprotonated ligands (L) coordinated to CuII through the oxygen and sulfur atoms in a cis arrangement. The
antitumor activity of the copper(II) complexes with acylthiourea ligands was evaluated in vitro against the
mouse mammary adenocarcinoma TA3 cell line. These complexes exhibited much higher cytotoxic activity
(IC50 values in the range of 3.9-6.9 μM) than their corresponding ligands (40-240 μM), which indicates that
the coordination of the chelate ligands around the CuII enhances the antitumor activity and, furthermore, this
result confirmed that the participation of the nitro and chloro substituent groups in the complex activities is
slightly relevant. The high accumulation of the complexes Cu(L2)2 and Cu(L3)2 in TA3 tumor cells and the
much faster binding to cellular DNA than Cu(L1)2 are consistent with the in vitro cytotoxic activities found
for these copper complexes
Synthesis, Characterization and Antitumor Activity of cis-bis(acylthioureato) platinum(II) Complexes, cis-[PtL2] [HL1=N,N-Diphenyl-N'-Benzoylthiourea or HL2=N,N-diphenyl-N'-(p-nitrobenzoyl)thiourea]
A low-molecular weight chromium-containing fraction of the material resulting from dichromate
reduction by bovine liver homogenate was investigated by NMR and ES-MS. The ES-MS spectrum showed a
readily detectable peak at m/z 786.1. The same molecular weight reasonably agreed with the relatively low
diffusion coefficient measured by NMR-DOSY experiments on the main species observed in the 1H NMR
spectrum. At least two downfield shifted and broad paramagnetic signals were apparent in the 1H NMR
spectrum. Temperature dependence of chemical shift was exploited in order to estimate the diamagnetic shift
of the signals in the diamagnetic region of the spectrum. 2D TOCSY, NOESY, COSY and 1H-13C HMQC
spectra revealed the presence of aromatic protons (which were assigned as His residues), Gly and some other
short chain amino-acids. Combinations of the molecular masses of such components together with acetate
(which is present in the solution) and chromium atoms allowed a tentative proposal of a model for the
compound
Изучение процессов неравновесного выхода водорода из металлических образцов (Ni,Ti) различной толщины различных видах стимуляции
Рассмотрены особенности неравновесного выхода водорода из образцов (Ni, Ti ) при различных способах насыщения материалов водородом ( электролиз, метод Сивертса, плазма ВЧ разряда) и стимуляции (термическая и стимуляция с высокой эффективной температурой).
Проанализированы современные подходы теоретического рассмотрения данных процессов, включая обратный эффект Мессбауэра.
Результаты работы актуальны для решения проблемы водородного охрупчивания конструкционных материалов в ядерной и водородной энергетике и предотвращения пассивирования примесных центров свечения в светодиодах.The features of the nonequilibrium hydrogen output from samples (Ni, Ti) at various methods of hydrogen saturation with materials (electrolysis, Sievert method, high-frequency discharge plasma) and stimulation (thermal and stimulation with high effective temperature) are considered.
Modern approaches to theoretical consideration of these processes, including the inverse Mossbauer effect, are analyzed.
The results of the work are relevant for the solution of the problem of hydrogen embrittlement of structural materials in nuclear and hydrogen energy and prevention of passivation of impurity centers of luminescence in light-emitting diodes
Virulence-associated genes, resistance genes and adhesion and probiotic activity tested by a new screening method
We established an automated screening method to characterize adhesion of
Escherichia coli to intestinal porcine epithelial cells (IPEC-J2) and their
probiotic activity against infection by enteropathogenic E. coli (EPEC). 104
intestinal E. coli isolates from domestic pigs were tested by PCR for the
occurrence of virulence-associated genes, genes coding for resistances to
antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion
rates and probiotic activity were examined for correlation with the presence
of these genes. Finally, data were compared with those from 93 E. coli
isolates from wild boars. Isolates from domestic pigs carried a broad variety
of all tested genes and showed great diversity in gene patterns. Adhesions
varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial
cell after 2 or 6 hours respectively. Most isolates from domestic pigs and
wild boars showed low adherence, with no correlation between
adhesion/probiotic activity and E. coli genes or gene clusters. The gene
sfa/foc, encoding for a subunit of F1C fimbriae did show a positive
correlative association with adherence and probiotic activity; however E. coli
isolates from wild boars with the sfa/foc gene showed less adhesion and
probiotic activity than E. coli with the sfa/foc gene isolated from domestic
pigs after 6 hour incubation. In conclusion, screening porcine E. coli for
virulence associated genes genes, adhesion to intestinal epithelial cells, and
probiotic activity revealed a single important adhesion factor, several
probiotic candidates, and showed important differences between E. coli of
domestic pigs and wild boars
Porcine E. coli: Virulence-Associated Genes, Resistance Genes and Adhesion and Probiotic Activity Tested by a New Screening Method
We established an automated screening method to characterize adhesion of Escherichia colito intestinal porcine epithelial cells (IPEC-J2) and their probiotic activity against infection by enteropathogenic E. coli (EPEC). 104 intestinal E. coli isolates from domestic pigs were tested by PCR for the occurrence of virulence-associated genes, genes coding for resistances to antimicrobial agents and metals, and for phylogenetic origin by PCR. Adhesion rates and probiotic activity were examined for correlation with the presence of these genes. Finally, data were compared with those from 93 E. coli isolates from wild boars.
Isolates from domestic pigs carried a broad variety of all tested genes and showed great diversity in gene patterns. Adhesions varied with a maximum of 18.3 or 24.2 mean bacteria adherence per epithelial cell after 2 or 6 hours respectively. Most isolates from domestic pigs and wild boars showed low adherence, with no correlation between adhesion/probiotic activity and E. coli genes or gene clusters. The gene sfa/foc, encoding for a subunit of F1C fimbriae did show a positive correlative association with adherence and probiotic activity; however E. coliisolates from wild boars with the sfa/foc gene showed less adhesion and probiotic activity thanE. coli with the sfa/foc gene isolated from domestic pigs after 6 hour incubation.
In conclusion, screening porcine E. coli for virulence associated genes genes, adhesion to intestinal epithelial cells, and probiotic activity revealed a single important adhesion factor, several probiotic candidates, and showed important differences between E. coli of domestic pigs and wild boars
KRAS, EGFR, PDGFR-α, KIT and COX-2 status in carcinoma showing thymus-like elements (CASTLE)
Background
CASTLE (Carcinoma showing thymus-like elements) is a rare malignant neoplasm of the thyroid resembling lymphoepithelioma-like and squamous cell carcinoma of the thymus with different biological behaviour and a better prognosis than anaplastic carcinoma of the thyroid.
Methods
We retrospectively investigated 6 cases of this very rare neoplasm in order to investigate the mutational status of KRAS, EGFR, PDGFR-α and KIT, as well as the immunohistochemical expression pattern of CD117, EGFR and COX-2, and possibly find new therapeutic targets.
Results
Diagnosis was confirmed by a moderate to strong expression of CD5, CD117 and CK5/6, whereas thyroglobulin, calcitonin and TTF-1 were negative in all cases. Tumors were also positive for COX-2 and in nearly all cases for EGFR. In four cases single nucleotide polymorphisms (SNPs) could be detected in exon 12 of the PDGFR-α gene (rs1873778), in three cases SNPs were found in exon 20 of the EGFR gene (rs1050171). No mutations were found in the KIT and KRAS gene.
Conclusions
All tumors showed a COX-2 expression as well as an EGFR expression except for one case and a wild-type KRAS status. No activating mutations in the EGFR, KIT and PDGFR-α gene could be detected. Our data may indicate a potential for targeted therapies, but if these therapeutic strategies are of benefit in CASTLE remains to be determined
Seroepidemiological study on the spread of SARS-CoV-2 in Germany:
The SARS-CoV-2 coronavirus has spread rapidly across Germany. Infections are likely to be under-recorded in the notification data from local health authorities on laboratory-confirmed cases since SARS-CoV-2 infections can proceed with few symptoms and then often remain undetected. Seroepidemiological studies allow the estimation of the proportion in the population that has been infected with SARS-CoV-2 (seroprevalence) as well as the extent of undetected infections.
The ‘CORONA-MONITORING bundesweit’ study (RKI-SOEP study) collects biospecimens and interview data in a nationwide population sample drawn from the German Socio-Economic Panel (SOEP).
Participants are sent materials to self-collect a dry blood sample of capillary blood from their finger and a swab sample from their mouth and nose, as well as a questionnaire. The samples returned are tested for SARS-CoV-2 IgG antibodies and SARS-CoV-2 RNA to identify past or present infections.
The methods applied enable the identification of SARS-CoV-2 infections, including those that previously went undetected. In addition, by linking the data collected with available SOEP data, the study has the potential to investigate social and health-related differences in infection status. Thus, the study contributes to an improved understanding of the extent of the epidemic in Germany, as well as identification of target groups for infection protection
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