Modelling in-situ Matrix Diffusion at Palmottu Natural Analogue Study Site in SW Finland.

1992 ◽  
Vol 294 ◽  
Author(s):  
Karl Rasilainen ◽  
Juhani Suksi
Keyword(s):  
Diffusion Theory ◽  
Crystalline Rock ◽  
Natural Fracture ◽  
Matrix Diffusion ◽  
Specific Data ◽  
Analogue Study ◽  
The Matrix ◽  
Simulated Concentration ◽  
And Migration

ABSTRACTRadioactive disequilibria, between U-238, U-234, and Th-230, in crystalline rock adjacent to a fracture, indicates mass transfer of U and Th between water in the fracture and the rock. The matrix diffusion theory was used to interpret the observed profiles of mobilized nuclides around the natural fracture. The interpretation of the profiles was based on the use of uranium series disequilibrium code, URSE, and migration code FTRANS. The model system was characterized using all available site-specific data, and the system evolution was outlined using the geology of the Palmottu site. The simulated concentration profiles, as a function of depth from the fracture surface, indicate that measured profiles can be modelled by matrix diffusion, assuming realistic initial and boundary conditions and diffusion times of 300,000 years.

scholarly journals A85 THE CLINICAL IMPACT OF COVID-19 DELAYS ON PLASTIC BILIARY STENT REMOVAL IN NOVA SCOTIA

2021 ◽  
Vol 4 (Supplement_1) ◽  
pp. 54-56
Author(s):  
D R Lim ◽  
M Tsai ◽  
S E Gruchy ◽  
J Jones ◽  
G Williams ◽  
...  
Keyword(s):  
Survival Analysis ◽  
Nova Scotia ◽  
Stent Placement ◽  
Biliary Stent ◽  
Biliary Stents ◽  
Stent Occlusion ◽  
Stent Removal ◽  
Kaplan Meier ◽  
And Migration

Abstract Background The COVID-2019 pandemic continues to restrict access to endoscopy, resulting in delays or cancellation of non-urgent endoscopic procedures. A delay in the removal or exchange of plastic biliary stents may lead to stent occlusion with consensus recommendation of stent removal or exchange at three-month intervals [1–4]. We postulated that delayed plastic biliary stent removal (DPBSR) would increase complication rates. Aims We aim to report our single-centre experience with complications arising from DPBSR. Methods This was a retrospective, single-center, observational cohort study. All subjects who had ERCP-guided plastic biliary stent placement in Halifax, Nova Scotia between Dec 2019 and June 2020 were included in the study. DPBSR was defined as stent removal >=90 days from insertion. Four endpoints were assigned to patients: 1. Stent removed endoscopically, 2. Died with stent in-situ (measured from stent placement to documented date of death/last clinical encounter before death), 3. Pending removal (subjects clinically well, no liver enzyme elevation, not expired, endpoint 1 Nov 2020), and 4. Complication requiring urgent reintervention. Kaplan-Meier survival analysis was used to represent duration of stent patency (Fig.1). Results 102 (47.2%) had plastic biliary stents placed between 2/12/2019 and 29/6/2020. 49 (48%) were female, and the median age was 68 (R 16–91). Median follow-up was 167.5 days, 60 (58.8%) subjects had stent removal, 12 (11.8%) died before replacement, 21 (20.6%) were awaiting stent removal with no complications (median 230d, R 30–332), 9 (8.8%) had complications requiring urgent ERCP. Based on death reports, no deaths were related to stent-related complications. 72(70.6%) of patients had stents in-situ for >= 90 days. In this population, median time to removal was 211.5d (R 91-441d). 3 (4.2%) subjects had stent-related complications requiring urgent ERCP, mean time to complication was 218.3d (R 94–441). Stent removal >=90 days was not associated with complications such as occlusion, cholangitis, and migration (p=1.0). Days of stent in-situ was not associated with occlusion, cholangitis, and migration (p=0.57). Sex (p=0.275), cholecystectomy (p=1.0), cholangiocarcinoma (p=1.0), cholangitis (p=0.68) or pancreatitis (p=1.0) six weeks prior to ERCP, benign vs. malignant etiology (p=1.0) were not significantly associated with stent-related complications. Conclusions Plastic biliary stent longevity may have been previously underestimated. The findings of this study agree with CAG framework recommendations [5] that stent removal be prioritized as elective (P3). Limitations include small sample size that could affect Kaplan-Meier survival analysis. Despite prolonged indwelling stent time as a result of COVID-19, we did not observe an increased incidence of stent occlusion or other complications. Funding Agencies None

scholarly journals Supramolecular ionic polymer/carbon nanotube composite hydrogels with enhanced electromechanical performance

2020 ◽  
Vol 9 (1) ◽  
pp. 478-488 ◽  
Author(s):  
Yun-Fei Zhang ◽  
Fei-Peng Du ◽  
Ling Chen ◽  
Ka-Wai Yeung ◽  
Yuqing Dong ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Ion Mobility ◽  
Artificial Muscles ◽  
Ionic Polymer ◽  
Composite Hydrogels ◽  
The Matrix ◽  
Electromechanical Performance ◽  
Carbon Nanotube Composite ◽  
Robotic Devices

AbstractElectroactive hydrogels have received increasing attention due to the possibility of being used in biomimetics, such as for soft robotics and artificial muscles. However, the applications are hindered by the poor mechanical properties and slow response time. To address these issues, in this study, supramolecular ionic polymer–carbon nanotube (SIPC) composite hydrogels were fabricated via in situ free radical polymerization. The polymer matrix consisted of carbon nanotubes (CNTs), styrene sulfonic sodium (SSNa), β-cyclodextrin (β-CD)-grafted acrylamide, and ferrocene (Fc)-grafted acrylamide, with the incorporation of SSNa serving as the ionic source. On applying an external voltage, the ions accumulate on one side of the matrix, leading to localized swelling and bending of the structure. Therefore, a controllable and reversible actuation can be achieved by changing the applied voltage. The tensile strength of the SIPC was improved by over 300%, from 12 to 49 kPa, due to the reinforcement effect of the CNTs and the supramolecular host–guest interactions between the β-CD and Fc moieties. The inclusion of CNTs not only improved the tensile properties but also enhanced the ion mobility, which lead to a faster electromechanical response. The presented electro-responsive composite hydrogel shows a high potential for the development of robotic devices and soft smart components for sensing and actuating applications.

scholarly journals In situ structure and organization of the influenza C virus surface glycoprotein

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Steinar Halldorsson ◽  
Kasim Sader ◽  
Jack Turner ◽  
Lesley J. Calder ◽  
Peter B. Rosenthal
Keyword(s):  
Membrane Fusion ◽  
Hexagonal Lattice ◽  
Surface Glycoprotein ◽  
Structural Basis ◽  
Virus Surface ◽  
The Matrix ◽  
Influenza C Virus ◽  
Subtomogram Averaging ◽  
Electron Cryotomography

AbstractThe lipid-enveloped influenza C virus contains a single surface glycoprotein, the haemagglutinin-esterase-fusion (HEF) protein, that mediates receptor binding, receptor destruction, and membrane fusion at the low pH of the endosome. Here we apply electron cryotomography and subtomogram averaging to describe the structural basis for hexagonal lattice formation by HEF on the viral surface. The conformation of the glycoprotein in situ is distinct from the structure of the isolated trimeric ectodomain, showing that a splaying of the membrane distal domains is required to mediate contacts that form the lattice. The splaying of these domains is also coupled to changes in the structure of the stem region which is involved in membrane fusion, thereby linking HEF’s membrane fusion conformation with its assembly on the virus surface. The glycoprotein lattice can form independent of other virion components but we show a major role for the matrix layer in particle formation.

scholarly journals Application of Furcellaran Nanocomposite Film as Packaging of Cheese

Polymers ◽  
2021 ◽  
Vol 13 (9) ◽  
pp. 1428
Author(s):  
Agnieszka Pluta-Kubica ◽  
Ewelina Jamróz ◽  
Gohar Khachatryan ◽  
Adam Florkiewicz ◽  
Pavel Kopel
Keyword(s):  
Silver Nanoparticles ◽  
Nanocomposite Film ◽  
Microbiological Quality ◽  
Inhibitory Effect ◽  
Quality Properties ◽  
In Situ Method ◽  
And Migration ◽  
Total Bacteria

There is a serious need to develop and test new biodegradable packaging which could at least partially replace petroleum-based materials. Therefore, the objective of this work was to examine the influence of the recently developed furcellaran nanocomposite film with silver nanoparticles (obtained by an in situ method) on the quality properties of two cheese varieties: a rennet-curd (gouda) and an acid-curd (quark) cheese. The water content, physicochemical properties, microbiological and organoleptic quality of cheese, and migration of silver nanoparticles were examined. Both the number of Lactococcus and total bacteria count did not differ during storage of gouda regardless of the packaging applied. The number of Lactococcus decreased in analogous quark samples. The use of the film slowed down and inhibited the growth of yeast in gouda and quark, respectively. An inhibitory effect of this film on mold count was also observed; however, only regarding gouda. The level of silver migration was found to be lower in quark than in gouda. The film improved the microbiological quality of cheeses during storage. Consequently, it is worth continuing research for the improvement of this film in order to enable its use in everyday life.

scholarly journals Development of a Decellularized Porcine Esophageal Matrix for Potential Applications in Cancer Modeling

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1055
Author(s):  
Hersh Chaitin ◽  
Michael L. Lu ◽  
Michael B. Wallace ◽  
Yunqing Kang
Keyword(s):  
Cell Growth ◽  
Lymphatic Vessels ◽  
Significant Loss ◽  
Cancer Cell Growth ◽  
Cell Growth And Migration ◽  
Decellularized Extracellular Matrix ◽  
Cancer Models ◽  
The Matrix ◽  
Potential Applications ◽  
And Migration

Many decellularized extracellular matrix-derived whole organs have been widely used in studies of tissue engineering and cancer models. However, decellularizing porcine esophagus to obtain decellularized esophageal matrix (DEM) for potential biomedical applications has not been widely investigated. In this study a modified decellularization protocol was employed to prepare a porcine esophageal DEM for the study of cancer cell growth. The cellular removal and retention of matrix components in the porcine DEM were fully characterized. The microstructure of the DEM was observed using scanning electronic microscopy. Human esophageal squamous cell carcinoma (ESCC) and human primary esophageal fibroblast cells (FBCs) were seeded in the DEM to observe their growth. Results show that the decellularization process did not cause significant loss of mechanical properties and that blood ducts and lymphatic vessels in the submucosa layer were also preserved. ESCC and FBCs grew on the DEM well and the matrix did not show any toxicity to cells. When FBS and ESCC were cocultured on the matrix, they secreted more periostin, a protein that supports cell adhesion on matrix. This study shows that the modified decellularization protocol can effectively remove the cell materials and maintain the microstructure of the porcine esophageal matrix, which has the potential application of studying cell growth and migration for esophageal cancer models.

scholarly journals The Sorting of Mitochondrial DNA and Mitochondrial Proteins in Zygotes: Preferential Transmission of Mitochondrial DNA to the Medial Bud

1998 ◽  
Vol 142 (3) ◽  
pp. 613-623 ◽  
Author(s):  
Koji Okamoto ◽  
Philip S. Perlman ◽  
Ronald A. Butow
Keyword(s):  
Mitochondrial Dna ◽  
Fluorescent Protein ◽  
Yeast Cells ◽  
Mitochondrial Matrix ◽  
Outer Membranes ◽  
Marker Proteins ◽  
The Matrix ◽  
Green Fluorescent ◽  
Mitochondrial Reticulum

Green fluorescent protein (GFP) was used to tag proteins of the mitochondrial matrix, inner, and outer membranes to examine their sorting patterns relative to mtDNA in zygotes of synchronously mated yeast cells in ρ+ × ρ0 crosses. When transiently expressed in one of the haploid parents, each of the marker proteins distributes throughout the fused mitochondrial reticulum of the zygote before equilibration of mtDNA, although the membrane markers equilibrate slower than the matrix marker. A GFP-tagged form of Abf2p, a mtDNA binding protein required for faithful transmission of ρ+ mtDNA in vegetatively growing cells, colocalizes with mtDNA in situ. In zygotes of a ρ+ × ρ+ cross, in which there is little mixing of parental mtDNAs, Abf2p–GFP prelabeled in one parent rapidly equilibrates to most or all of the mtDNA, showing that the mtDNA compartment is accessible to exchange of proteins. In ρ+ × ρ0 crosses, mtDNA is preferentially transmitted to the medial diploid bud, whereas mitochondrial GFP marker proteins distribute throughout the zygote and the bud. In zygotes lacking Abf2p, mtDNA sorting is delayed and preferential sorting is reduced. These findings argue for the existence of a segregation apparatus that directs mtDNA to the emerging bud.

The contribution of friction stress to the creep behaviour of the nickel-base in situ composite, γ—γ'-Cr 3 C 2

1980 ◽  
Vol 373 (1752) ◽  
pp. 93-109 ◽  
Keyword(s):  
Activation Energy ◽  
Creep Behaviour ◽  
Friction Stress ◽  
Matrix Alloy ◽  
Dislocation Motion ◽  
Self Diffusion ◽  
The Matrix ◽  
Nickel Base ◽  
Distribution Of Stress

Transient creep following stress reductions has been analysed by the method described by McLean (1980) to determine the friction stress σ 0 as a function of temperature and directional solidification conditions for the γ-γ'-Cr 3 Cr 2 in-situ composite and for the γ-γ' matrix alloy. These values of σ 0 are identical to the flow stresses at creep strain rates and can be identified with the sums of the barriers to dislocation motion through the matrix by climb around γ'-particles and Orowan bowing between the carbide fibres. The friction stress and the kinetics of deformation of the composite are determined by the matrix behaviour, whereas its creep strength depends on the distribution of stress between fibre and matrix. When the steady-state creep behaviour of γ-γ'-Cr 3 C 2 is analysed by using the usual power law description in terms of the effective stress σ — σ 0 , rather than the applied stress σ, the stress exponent is ca 4 and the activation energy is similar to the activation energy of self-diffusion for nickel. The results provide strong evidence for the operation of recovery-creep in both the composite and matrix alloys.

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