scholarly journals Using Plasma Etching to Access the Polymer Density Distribution and Diffusivity of Gel Particles

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2537
Author(s):  
Ivan J. Suarez ◽  
Benjamin Sierra-Martin ◽  
Antonio Fernandez-Barbero
Keyword(s):  
Diffusion Coefficient ◽  
Density Distribution ◽  
Plasma Etching ◽  
Polymer Network ◽  
Plasma Oxidation ◽  
Relaxation Length ◽  
Gel Particles ◽  
Before And After ◽  
Spatial Relaxation ◽  
Polymer Density

In this paper we examine the polymer density distribution of gel particles and its effect on solvent diffusivity through the polymer network. In order to access the inner particle regions, external polymer layers were removed by plasma etching, thus reducing them from the outside. Higher polymer densities after erosion showed internal heterogeneity, with the density increasing towards the center of the particles. An exponential decay polymer density model is proposed, and the spatial relaxation length measured. The diffusion of solvent through the particles, before and after the plasma oxidation, revealed a correlation between the diffusion coefficient and the internal density.

Evaluation of extraocular muscles in patients with thyroid associated ophthalmopathy using apparent diffusion coefficient measured by magnetic resonance imaging before and after radiation therapy

2021 ◽  
pp. 028418512110340
Author(s):  
Wu Yu ◽  
Lao Zheng ◽  
Zhang Shuo ◽  
Liu Xingtong ◽  
Jiang Mengda ◽  
...  
Keyword(s):  
Diffusion Coefficient ◽  
Radiation Therapy ◽  
Apparent Diffusion Coefficient ◽  
Extraocular Muscles ◽  
Clinical Activity ◽  
Inferior Rectus ◽  
Thyroid Associated Ophthalmopathy ◽  
Before And After ◽  
Apparent Diffusion ◽  
The Mean

Background Thyroid-associated ophthalmopathy (TAO) is an autoimmune orbital disease characterized by edema of extraocular muscles (EOMs). Purpose To characterize the inflammation of EOMs in patients with TAO before and after radiation therapy using apparent diffusion coefficient (ADC) and to analyze the correlation between ADC and clinical activity of TAO. Material and Methods The ADCs of superior rectus (SR), inferior rectus (IR), medial rectus (MR), and lateral rectus (LR) muscles were measured in 52 eyes of 26 patients with TAO before and three months after orbital radiation therapy. In addition, 38 eyes of 20 healthy volunteers were included. The clinical activity score (CAS) was evaluated. The ADC maps were reconstructed and measured on the coronal diffusion-weighted imaging (DWI) sequence and calculated in mm2/s. Results The mean ADCs of EOMs before treatment were 1.42 ± 0.23 in SR, 1.37 ± 0.23 in IR, 1.41 ± 0.21 in MR, and 1.28 ± 0.25 in LR. The mean ADCs after treatment were 1.27 ± 0.18, 1.22 ± 0.26, 1.30 ± 0.22, and 1.15 ± 0.21, respectively. The ADCs were significantly decreased after treatment (all P < 0.001). The ADCs of patients with TAO were significantly higher than those of controls. There was a statistically significant correlation between the mean ADCs and the CAS in each patient with TAO both before and after treatment (before: r = 0.520; P < 0.001; after: r = 0.625; P < 0.001). Conclusion The ADC values of EOMs can be exploited as a quantitative indicator to evaluate the clinical activity and monitor the therapeutic responses of patients with TAO.

scholarly journals The rainfall effect onto solidification and stabilization of heavy metal-polluted sediments

2020 ◽  
Vol 7 (7) ◽  
pp. 192234
Author(s):  
Yan Sun ◽  
Daofang Zhang ◽  
Feipeng Li ◽  
Hong Tao ◽  
Moting Li ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
Diffusion Coefficient ◽  
Simulated Acid Rain ◽  
Curing Process ◽  
Deterioration Rate ◽  
Before And After ◽  
Calculated Diffusion Coefficient ◽  
Leaching Procedure

Rainfall makes impacts on the process of solidification/stabilization (S/S) and the long-term safety of solidified matrix. In this study, the effect of rainfall on solidification/stabilization process was investigated by the rainfall test. The unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) were adopted to characterize the properties of S/S sediments before and after the rainfall test. The samples cured for 28 days were selected for semi-dynamic leaching tests with a simulated acidic leachant prepared at pH of 2.0, 4.0 and 7.0. The effectiveness of S/S treatment was evaluated by diffusion coefficient ( D e ) and leachability index (LX). The results indicated that UCS decreased at maximum deterioration rate of 34.23% after 7 days of curing, along with the minimum rate of 7.98% after 28 days by rainfall, with greater than 14 days referred. The rainfall had little effect on the leaching characteristics of heavy metals during the curing process. However, the simulated acid rain made significant impacts on the leaching behaviours of the heavy metals in the S/S materials. All the values of cumulative fraction of leached heavy metals were less than 2.0%, exhibition of good stabilization of cement. Furthermore, the calculated diffusion coefficient ( D e ) for Cu was 1.28 × 10 1 cm 2 s –1 , indicating its low mobility of heavy metal ions in S/S sediments. Furthermore, the calculated diffusion coefficients ( D i ) for Cd, Cu and Pb were 7.44 × 10 −11 , 8.18 × 10 −12 and 7.85 × 10 −12 cm 2 s –1 , respectively, indicating their relatively low mobility of heavy metal in S/S sediments.

scholarly journals Polymer gel with a flexible and highly ordered three-dimensional network synthesized via bond percolation

2019 ◽  
Vol 5 (12) ◽  
pp. eaax8647 ◽  
Author(s):  
X. Li ◽  
S. Nakagawa ◽  
Y. Tsuji ◽  
N. Watanabe ◽  
M. Shibayama
Keyword(s):  
Network Formation ◽  
General Scheme ◽  
Polymer Network ◽  
Three Dimensional ◽  
Geometric Constraints ◽  
Polymer Chains ◽  
Bond Percolation ◽  
Polymer Gel ◽  
Temporal Correlations ◽  
Before And After

Gels are a soft elastic material consisting of a three-dimensional polymer network with nanometer-sized pores and are used in a variety of applications. However, gel networks typically have a substantial level of defects because the network formation reaction proceeds stochastically. In this study, we present a general scheme to fabricate gels with extremely low levels of defects by applying geometric constraints into pregel solution based on the “bond percolation” concept. In the formed gel, stationary laser speckles, which are an indicator of spatial defects, were not observed at all. In addition, we found that the concentration fluctuations of the polymer chains were ergodic across the whole gel network. In such a homogeneous gel, both the spatial and temporal correlations of polymer chains are the same before and after gelation.

scholarly journals The Value of Intravoxel Incoherent Motion (IVIM) Magnetic Resonance Imaging in the Evaluation of the Osteosarcoma Response to Preoperative Neoadjuvant Chemotherapy in Teens

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Houdong Zuo
Keyword(s):  
Magnetic Resonance Imaging ◽  
Diffusion Coefficient ◽  
Magnetic Resonance ◽  
Neoadjuvant Chemotherapy ◽  
Roc Curves ◽  
Intravoxel Incoherent Motion ◽  
Imaging Biomarkers ◽  
Fast Diffusion ◽  
Resonance Imaging ◽  
Before And After

Purpose. To investigate the value of intravoxel incoherent motion (IVIM) magnetic resonance imaging in the evaluation of the osteosarcoma (OS) response to preoperative neoadjuvant chemotherapy (NAC) in teens. Methods. Eighteen consecutive osteosarcoma patients (12 males and 6 females) diagnosed by histopathology were enrolled. All enrolled patients received NAC and underwent MRI examinations before and after 2 cycles of NAC. The volume (V), apparent diffusion coefficient (ADC), (slow) diffusion coefficient (D), pseudo-perfusion (fast) diffusion coefficient (D⁎or D star), and perfusion fractions (f) of the OS before and after NAC were measured and analysed. The sensitivity and the specificity of the ADC, D, D⁎ and f values and the correlation between changes in volume (ΔV) and the IVIM-derived parameters (ΔADC, ΔD, ΔD⁎ and Δf) were also calculated and analysed. Paired Student’s t-tests, receiver operating characteristic (ROC) curves, and Spearman correlation analyses were used. Results. The mean volume of the OS after NAC decreased significantly (61.55±9.3 cm3 vs 40.26±4.1 cm3) (P<0.05). After NAC, the ADC (1.21±0.09 × 10-3 mm2/s vs 1.73±0.11 × 10-3 mm2/s) and D (1.14±0.09 × 10-3 mm2/s vs 1.63±0.1 × 10-3 mm2/s) values increased and f (28.58±1.37% vs 20.93±1.16%) values decreased significantly (P<0.05), while D⁎ (9.17±0.98 × 10-3 mm2/s vs 8.94±0.13 × 10-3 mm2/s) values changed slightly (P>0.05). The AUC values of ADC (0.938) and D (0.943) were higher than those of D⁎ (0.574) and f (0.765). The sensitivity and specificity of ADC (0.778, 1) and D (0.944, 0.833) values were superior to those of D⁎ (0.278, 0.722) and f (0.5, 0.944) values. No significant correlations were found between the ΔV and ΔADC, ΔD, ΔD⁎ and Δf values (P>0.05). Conclusion. IVIM-derived parameters ADC and D have the potential to be imaging biomarkers for evaluation of the therapeutic response to NAC in OS patients.

Reproducibility of measurements with a semi-automatic software package for the evaluation of rectal cancer

2019 ◽  
Vol 61 (5) ◽  
pp. 586-594
Author(s):  
Lisa Hörberg ◽  
Daniel Roth ◽  
Peter Leander ◽  
Sven Månsson ◽  
Tobias Fält ◽  
...  
Keyword(s):  
Rectal Cancer ◽  
Diffusion Coefficient ◽  
Apparent Diffusion Coefficient ◽  
Lymph Nodes ◽  
Software Package ◽  
Cancer Management ◽  
Mri Staging ◽  
Before And After ◽  
Apparent Diffusion ◽  
Chemoradiation Treatment

Background Staging of rectal cancer with MRI has major impact on treatment choice and may be of importance in new cancer management strategies such as “wait-and-see” policy. Purpose To assess the reproducibility of a software package recently developed at our department to measure volumes, apparent diffusion coefficient, and the skewness of apparent diffusion coefficient in lymph nodes and tumors in rectal cancer patients before and after chemoradiation treatment. Material and Methods This study included 20 consecutive patients with biopsy-verified rectal cancer, in whom MRI staging had been performed both before and after chemoradiation treatment. The diffusion-weighted images were transferred to the software. The volume, apparent diffusion coefficient, and skewness were determined for 93 lymph nodes and 40 tumors. The volumes were compared with manual measurements of the volume of the same lymph nodes and tumors. Results The agreement in semi-automatic measurements of lymph nodes was very good (ICC = 0.99), and in tumors good (ICC = 0.88). The agreement in manual measurements of lymph nodes was very good (ICC = 0.95) when all lymph nodes were included, but low (ICC = 0.52) if three outliers were excluded. Bland–Altman plots showed clear agreement between manual and semi-automatic measurements in the lymph nodes, but not in measurements of tumors. The values of apparent diffusion coefficient and skewness in tumors differed before and after treatment but did not differ in lymph nodes as a group. Conclusion The software package showed a high degree of reproducibility in measurements on lymph nodes but requires further development to improve the reproducibility of tumor measurements.

Grain Boundary Diffusion in Co/Cu and Co/Cr Magnetic Thin Films

1993 ◽  
Vol 313 ◽  
Author(s):  
John G. Holl-Pellerin ◽  
S.G.H. Anderson ◽  
P.S. Ho ◽  
K.R. Coffey ◽  
J.K. Howard ◽  
...  
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Diffusion Coefficient ◽  
Grain Boundary ◽  
Photoelectron Spectroscopy ◽  
Boundary Diffusion ◽  
Magnetic Thin Films ◽  
Grain Boundary Diffusion ◽  
X Ray ◽  
Before And After

ABSTRACTX-ray photoelectron spectroscopy (XPS) has been used to investigate grain boundary diffusion of Cu and Cr through 1000 Å thick Co films in the temperature range of 325°C to 400°C. Grain boundary diffusivities were determined by modeling the accumulation of Cu or Cr on Co surfaces as a function of time at fixed annealing temperature. The grain boundary diffusivity of Cu through Co is characterized by a diffusion coefficient, D0gb, of 2 × 104 cm2/sec and an activation energy, Ea,gb, of 2.4 eV. Similarly, Cr grain boundary diffusion through Co thin films occurs with a diffusion coefficient, Do,gb, of 6 × 10-2cm2/sec and an activation energy, Ea,gb of 1.8 eV. The Co film microstructure has been investigated before and after annealing by x-ray diffraction and transmission electron Microscopy. Extensive grain growth and texturing of the film occurred during annealing for Co deposited on a Cu underlayer. In contrast, the microstructure of Co deposited on a Cr underlayer remained relatively unchanged upon annealing. Magnetometer Measurements have shown that increased in-plane coercivity Hc, reduced remanence squareness S, and reduced coercive squareness S* result from grain boundary diffusion of Cu and Cr into the Co films.

scholarly journals Cerebral blood flow, transit time, and apparent diffusion coefficient in moyamoya disease before and after acetazolamide

2016 ◽  
Vol 59 (1) ◽  
pp. 5-12 ◽  
Author(s):  
Christian Federau ◽  
Soren Christensen ◽  
Zungho Zun ◽  
Sun-Won Park ◽  
Wendy Ni ◽  
...  
Keyword(s):  
Blood Flow ◽  
Diffusion Coefficient ◽  
Cerebral Blood Flow ◽  
Apparent Diffusion Coefficient ◽  
Transit Time ◽  
Moyamoya Disease ◽  
Before And After ◽  
Apparent Diffusion

DEPTH-DEPENDENT MIXING OF AN AlAs-GaAs SUPERLATTICE BY ION IMPLANTATION

1985 ◽  
Vol 56 ◽  
Author(s):  
S.A. SCHWARZ ◽  
T. VENKATESAN ◽  
R. BHAT ◽  
M. KOZA ◽  
H.W. YOON ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Diffusion Coefficient ◽  
Ion Implantation ◽  
Secondary Ion Mass Spectrometry ◽  
Mixing Effect ◽  
Thermal Mixing ◽  
Projected Range ◽  
Ion Mass Spectrometry ◽  
Before And After ◽  
Secondary Ion

AbstractThe effects of implantation and annealing on an AlAs-GaAs superlattice grown by OMCVD is examined with SIMS (secondary ion mass spectrometry). Several 180 keV 28Si+ implants, with doses ranging from 3 × 1013 to 3 × 1015 cm−2, are examined before and after a three hour 850 C anneal. While the implantation by itself causes some intermixing in the vicinity of the projected range, the 850 C thermal anneal induces significant mixing at depths well beyond the implant range. In the region of maximum implant damage, however, the post-thermal mixing effect is inhibited. Depth dependent diffusion lengths of Al and Si are derived from the SIMS data. The diffusion coefficient of Si is markedly enhanced in the mixed regions.

Transport Properties of Magnetic Nanowires with Multiple Constrictions Formed by FIB

2004 ◽  
Vol 818 ◽  
Author(s):  
Tie Liu ◽  
Yihong Wu
Keyword(s):  
Electrical Properties ◽  
Electrochemical Deposition ◽  
Oxygen Plasma ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Magnetic Nanowires ◽  
Plasma Oxidation ◽  
Metal Electrodes ◽  
Filtration Membranes ◽  
Before And After

AbstractNi nanowires were fabricated by electrochemical deposition in the pores of alumina filtration membranes, with the diameter around 200nm. To study the magnetic and electrical properties of Ni nanowires, individual nanowire was selected and connected with metal electrodes. Single and multiple constrictions were formed on the nanowires by focused ion beam (FIB). The wires were further thinned using oxygen plasma oxidation. Magnetoresistance curves were studied and compared before and after FIB trimming and oxidization.

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