High-density Matrix Research Articles

Amelioration of breast cancer therapies through normalization of tumor vessels and microenvironment: paradigm shift to improve drug perfusion and nanocarrier permeation.

Breast cancer (BC) is the most commonly diagnosed cancer among women. Chemo-, immune- and photothermal therapies are employed to manage BC. However, the tumor microenvironment (TME) prevents free drugs and nanocarriers (NCs) from entering the tumor premises. Formulation scientists rely on enhanced permeation and retention (EPR) to extravasate NCs in the TME. However, recent research has demonstrated the inconsistent nature of EPR among different patients and tumor types. In addition, angiogenesis, high intra-tumor fluid pressure, desmoplasia, and high cell and extracellular matrix density resist the accumulation of NCs in the TME. In this review, we discuss TME normalization as an approach to improve the penetration of drugs and NCSs in the tumor premises. Strategies such as normalization of tumor vessels, reversal of hypoxia, alleviation of high intra-tumor pressure, and infiltration of lymphocytes for the reversal of therapy failure have been discussed in this manuscript. Strategies to promote the infiltration of anticancer immune cells in the TME after vascular normalization have been discussed. Studies strategizing time points to administer TME-normalizing agents are highlighted. Mechanistic pathways controlling the angiogenesis and normalization processes are discussed along with the studies. This review will provide greater tumor-targeting insights to the formulation scientists.

Smart Metrology Control of Through Silicon Via Etching Process for High End Devices

In this paper, we report on an innovative process characterization solution that aims to control the uniformity of the Through Silicon Via (TSV) etching process. The solution relies on measuring complementary geometric characteristics of the open Through-Silicon-VIA (TSV) that are key to establish a reliable vertical interconnection. When TSV are fabricated either in high-density matrix or in isolated locations, the solution presented here allows the non-destructive reliable measurement of top / bottom diameter, depth, and thickness of top hard mask layer with a combination of optical techniques. As example of use case, we present the result of the characterization of three different products hosting TSV with top diameter as small as 3 μm and aspect ratio up to 17:1. The new methodology is compared to the state of the art of metrology control solutions used in the semiconductor industry.

Comparative Tensile Properties and Collagen Patterns in Domestic Cat (Felis catus) and Dog (Canis lupus familiaris) Ovarian Cortical Tissues.

The importance of the ovarian extracellular environment and tissue rigidity on follicle survival and development has gained attention in recent years. Our laboratory has anecdotally observed differences in the rigidity of domestic cat and dog ovarian cortical tissues, which have been postulated to underlie the differences in in vitro culture responses between the species, wherein cat ovarian tissues display higher survival in extended incubation. Here, the tensile strengths of cat and dog ovarian cortical tissues were compared via micropipette aspiration. The underlying collagen patterns, including fiber length, thickness, alignment, curvature, branch points and end points, and overall tissue lacunary and high-density matrix (HDM) were quantified via picrosirius red staining and TWOMBLI analysis. Finally, we explored the potential of MMP (-1 and -9) and TIMP1 supplementation in modulating tissue rigidity, collagen structure, and follicle activation in vitro. No differences in stiffness were observed between cat or dog cortical tissues, or pre- versus post-pubertal status. Cat ovarian collagen was characterized by an increased number of branch points, thinner fibers, and lower HDM compared with dog ovarian collagen, and cat tissues exposed to MMP9 in vitro displayed a reduced Young's modulus. Yet, MMP exposure had a minor impact on follicle development in vitro in either species. This study contributes to our growing understanding of the interactions among the physical properties of the ovarian microenvironment, collagen patterns, and follicle development in vitro.

Novel Electrode Designs for Electrotactile Stimulation of the Finger: A Comparative Assessment.

Electrotactile stimulation can be an attractive technology to restore tactile feedback in different application scenarios (e.g., virtual and augmented reality, tele-manipulation). This technology allows designing compact solutions with no mechanical elements that can integrate a high-density matrix of stimulation points. The present study introduced four novel multi-pad finger-electrode designs with different arrangements (two matrix and two circular) and shapes of active pads (producing sensation) and reference pads (ideally, no sensation produced below the pad). The electrodes were used to investigate the subjects' ability to spatially discriminate active pads within phalanges individually (6-9 pads) as well as across the full finger (18-19 pads). The tests were conducted in 12 subjects and the results showed that all designs led to high success rates when applied to the fingertip (70-81%). When tested on the full finger, the matrix and circular designs were characterized with similar performance (54-57%), and when the phalanges were analyzed individually, the spatial discrimination was best at the fingertip. Additionally, new approaches for faster amplitude calibration were proposed and tested, demonstrating that calibration duration can be reduced by approximately 40% compared to the standard approach of calibrating single pads individually. Finally, discrimination tests of dynamic tactile patterns were conducted using circular and matrix designs on the fingertip and full finger, respectively. The tests showed that the different patterns generated by the two arrangements could be clearly discriminated, especially in the case of full-finger matrix-style patterns. The present study, therefore, provides several important insights that are relevant when delivering tactile feedback to the finger using an electrotactile interface.

Symbol Position Recovery for Optical Camera Communication With High-Density Matrix Codes

Symbol Position Recovery for Optical Camera Communication With High-Density Matrix Codes

Dynamic Model-Based Safety Margins for High-Density Matrix Headlight Systems

Real-time masking of vehicles in a dynamic road environment is a demanding task for adaptive driving beam systems of modern headlights. Next-generation high-density matrix headlights enable precise, high-resolution projections, while advanced driver assistance systems enable detection and tracking of objects with high update rates and low-latency estimation of the pose of the ego-vehicle. Accurate motion tracking and precise coverage of the masked vehicles are necessary to avoid glare while maintaining a high light throughput for good visibility. Safety margins are added around the mask to mitigate glare and flicker caused by the update rate and latency of the system. We provide a model to estimate the effects of spatial and temporal sampling on the safety margins for high-and low-density headlight resolutions and different update rates. The vertical motion of the ego-vehicle is simulated based on a dynamic model of a vehicle suspension system to model the impact of the motion-to-photon latency on the mask. Using our model, we evaluate the light throughput of an actual matrix headlight for the relevant corner cases of dynamic masking scenarios depending on pixel density, update rate, and system latency. We apply the masks provided by our model to a high beam light distribution to calculate the loss of luminous flux and compare the results to a light throughput approximation technique from the literature.

Fission gas retention of densely packed uranium carbonitride tristructural-isotropic fuel particles in a 3D printed SiC matrix

The Transformational Challenge Reactor (TCR) fuel form was designed to contain large, densely packed uranium carbonitride (UCN) tristructural-isotropic (TRISO) fuel particles within a 3D printed SiC matrix, increasing the uranium density compared to conventional TRISO fuel forms and offering full geometric freedom for core design. This work summarizes initial low-burnup, high-power irradiation testing of TCR fuel materials, including loose UCN TRISO particles and integral fuel compacts with ∼55% TRISO particles by volume, to evaluate fission gas retention. Fission gasses were fully retained in all loose particle tests and in integral compacts irradiated at low (<250 °C) surface temperatures. Initial testing at higher (∼700–750 °C) fuel surface temperatures showed fission gas release (FGR) and complete fracture of three compacts, but no FGR was observed in later high temperature tests (∼300–750 °C) of both fueled compacts and loose TRISO particles. Calculated thermal stresses in the failed compacts were far less than the measured strength of the SiC matrix and the stresses in some failed compacts were less than those in compacts that did not show FGR. Thermal stress-induced matrix cracks also would not cause complete fracture because the tensile stresses transition to compression in the higher temperature regions. Therefore, fuel failure was likely not caused by thermal stresses and may have been related to leakage currents from the electrical heaters and erratic fuel surface temperatures that were only observed in the test for which failure was observed. In any case, the matrix cracks propagated through the coatings of TRISO particles located in the high-density matrix regions on the peripheries of the compacts, resulting in measurable fission gas release. The discussion focuses on the importance of understanding matrix density distributions and the particle-matrix interface properties to prevent matrix cracks from causing TRISO particle failures.

Comparison of the Effectiveness of Fluoride versus Grape Seed Extract in Biomimetic Remineralization of Dentin

This study aims to compare the remineralization efficiency of grape seed extract versus fluoride in artificial carious dentin lesions in the biomimetic remineralization procedure. One hundred and twelve extracted impacted human teeth were demineralized for 10 days and divided into 4 groups. Demineralization group (DM), remineralization group (RM group), remineralization fluoride group (RM F), remineralization grape seed extract group (RM GSE). Demineralization (DM) group were stored in physiological saline after demineralization. RM F was kept in 1000 ppm fluorine solution and RM GSE was kept in 6.5% grape seed extract for 10 min. RM, RM F, RM GSE groups were stored in simulated body fluid (SBF) with biomimetic analogues and Portland cement discs for 6 weeks. The specimens were evaluated by microhardness test, elasticity modulus measurement, and scanning electron microscope (SEM) analysis. Kruskal–Wallis H test with Bonferroni correction was used for between-group comparisons. Microhardness and elasticity modulus values differed significantly among the groups, with the highest values in the RM-GSE group, followed by the RM-F group, RM group, and DM group. SEM images showed granular structure formations in the RM-GSE and RM-F groups. It is concluded that although remineralization can occur by mineral precipitation in structures with high organic matrix density such as dentin, the collagen structure must be supported to increase the degree of remineralization.

The Influence of Matrix Density on The Weibull Modulus of Natural Fiber Reinforced Nanocomposites

In recent decades, polymer composites have gained significant interests within the research community due to its high strength-to-weight ratio. Its properties, such as low cost, lightweight, corrosion resistance, and impact resistance, make it desirable for both household and industrial applications. However, the reliability of the composite model with density influence is still challenging. In this study, experiments were carried out using epoxy systems of varying densities to fabricate oil palm empty fruit bunch (OPEFB) carbon nanoparticle composites to investigate the influence of matrix density on its Weibull modulus. It is found that the increase in matrix density increases the nanocomposite reliability. A Weibull modulus of 9.5, 82.2 and 183.4 were obtained for low, medium and high matrix density nanocomposites, respectively. Such findings would facilitate the development of particle-reinforced composites.

VO2-based ultra-reconfigurable intelligent reflective surface for 5G applications

As demand for higher capacity wireless communications increases, new approaches are needed to improve capacity. The lack of configurable radio platforms and power consumed to create new signals are some of the limitations preventing further advancements. To address these limitations, we propose an Ultra-Reconfigurable Intelligent Surface (URIS) platform based on the metal-to-insulator transition property of VO2. A VO2 layer is placed on a high-density micro-heater matrix consisting of pixels that can be electronically switched on. With this manner of control, heat can be transferred to selected areas of the VO2 layer and convert it to highly conductive metallic phase. This technique allows dynamically changing the shape of the reflection surface with high speed. We numerically investigated the heat activated switching and RF reflection characteristics of a reflectarray designed for potential 5G applications operating at 32 GHz. It consists of heating pixels with the size of 40 × 40 μm which can generate metallic VO2 patches or arbitrary shapes with ~ 100 × 100 μm spatial resolution. Our analyses resulted in large phase range of ~ 300° and approximate losses of −2 dB. The proposed device can serve as a novel platform for ultra-reconfigurable reflectarrays, other IRSs, and various wide spectral range RF applications.

Temporal coherency of mechanical stimuli modulates tactile form perception

The human hand can detect both form and texture information of a contact surface. The detection of skin displacement (sustained stimulus) and changes in skin displacement (transient stimulus) are thought to be mediated in different tactile channels; however, tactile form perception may use both types of information. Here, we studied whether both the temporal frequency and the temporal coherency information of tactile stimuli encoded in sensory neurons could be used to recognize the form of contact surfaces. We used the fishbone tactile illusion (FTI), a known tactile phenomenon, as a probe for tactile form perception in humans. This illusion typically occurs with a surface geometry that has a smooth bar and coarse textures in its adjacent areas. When stroking the central bar back and forth with a fingertip, a human observer perceives a hollow surface geometry even though the bar is physically flat. We used a passive high-density pin matrix to extract only the vertical information of the contact surface, suppressing tangential displacement from surface rubbing. Participants in the psychological experiment reported indented surface geometry by tracing over the FTI textures with pin matrices of the different spatial densities (1.0 and 2.0 mm pin intervals). Human participants reported that the relative magnitude of perceived surface indentation steeply decreased when pins in the adjacent areas vibrated in synchrony. To address possible mechanisms for tactile form perception in the FTI, we developed a computational model of sensory neurons to estimate temporal patterns of action potentials from tactile receptive fields. Our computational data suggest that (1) the temporal asynchrony of sensory neuron responses is correlated with the relative magnitude of perceived surface indentation and (2) the spatiotemporal change of displacements in tactile stimuli are correlated with the asynchrony of simulated sensory neuron responses for the fishbone surface patterns. Based on these results, we propose that both the frequency and the asynchrony of temporal activity in sensory neurons could produce tactile form perception.

The investigating on mechanical properties of ultra-high strength and ultra-high ductility cementitious composites (UHS-UHDCC)

This study presents an ultra-high strength and ultra-high ductility cementitious composites (UHS-UHDCC) with a compressive strength higher than 160 ​MPa and an uniaxial tensile ductility exceeding 6%. When the mixture ratio is 0.4SF ​+ ​W0.19 ​+ ​PE, the UHS-UHDCC's compressive strength, compression elastic modulus, uniaxial tensile ductility, four-point bending mid-span deflection is 163 ​MPa, 54 ​GPa, more than 6% and 29.72 ​mm, respectively. The toughness at the ultimate mid-span deflection accurately reflects the energy absorption capacity of UHS-UHDCC. Compared with high-strength matrix without fiber, the flexural strength of USH-UHDCC grows 53.21%, its compressive strength only grows 8.24%, the effect of fiber on the flexural strength is more pronounced, and it shows a residual compressive strength of 40%, residual flexural strength of 50%, a good compression deformation capacity and compression toughness. The combination of high fiber dispersion, high matrix density, appropriate interfacial bonding strength, and high tensile strength and high elastic modulus of PE fiber achieves the ultra-high strength and ultra-high ductility of UHS-UHDCC.

Wholly vascularized millimeter-sized engineered tissues by cell-sized microscaffolds.

The in vitro fabrication of wholly vascularized millimeter-sized engineered tissues is still a key challenge in the tissue engineering field. Recently we reported a unique approach ‘sedimentary culture’ using a collagen microfiber (CMF) to fabricate large-scale engineered tissues. The millimeter-sized tissues with high extracellular matrix (ECM) density were easily obtained by centrifugation of cells and CMFs and subsequent cultivation because the CMFs acted as a micrometer-sized scaffold. However, cell distribution in the obtained tissues was not homogeneous because of the different sedimentation velocity of the cells and CMFs because of their size difference.Here we report the fabrication of wholly vascularized millimeter-sized engineered tissues using cell-sized CMFs. To avoid dissolving, vacuum drying was performed at 200 °C for 24 h for thermal crosslinking of primary amine groups of type I collagen. The 200- and 20-μm-sized CMFs (CMF-200 and CMF-20) were obtained by homogenization and subsequent sonication of the crosslinked collagen. Interestingly, the CMF-20 indicated a similar sedimentation velocity with cells because of their same size range, thus uniform millimeter-sized tissue with homogeneous cell distribution was fabricated by the sedimentary culture method. To form a whole blood capillary structure in the tissues, fibronectin (FN) was adsorbed on the surface of CMF-20 to stimulate endothelial cell migration. The distribution of the blood capillary network in 1.6-mm-sized tissues was markedly improved by FN-adsorbed CMF-20 (FN-CMF-20). Sedimentary culture using FN-CMF-20 will create new opportunities in tissue engineering for the in vitro fabrication of wholly vascularized millimeter-sized engineered tissues.

Impact of content and length of curauá fibers on mechanical behavior of extruded cementitious composites: Analysis of variance

The use of composite materials in construction has grown considerably in recent years, such as cementitious matrices and concrete reinforced with fibers. The vegetable fibers have become an alternative due to its abundance, low cost and low energy consumption for its production, and appropriate properties mechanical. Curauá fiber is a plant native from Amazonas harvested manually in commercial farming and it is used in the manufacture of ropes and baskets or as reinforcement in composite with organic matrix of components for cars, buses and trucks. On the other hand, the extrusion process can produce composites with high-density matrix with fibers, low permeability and good interface between fiber and matrix. This process is also compatible with the use of vegetable fibers as raw materials in the production of cost-effective construction elements such as ceiling panels and drywalls. The objective of this research was use the analysis of variance (ANOVA) for evaluating with rigor mathematical the influence of content and length of curauá fibers on the mechanical behavior of the extruded cementitious composites. Composites without fibers and reinforced with 1% and 2% by mass of fibers as well as 6 mm and 10 mm of length these curauá fibers were evaluated. The composites with fibers of 10 mm have showed better mechanical results. Besides, the composites with fibers curauá after 200 accelerated aging cycles were better than one non-aging.

Upper Arm Motion High-Density sEMG Recognition Optimization Based on Spatial and Time-Frequency Domain Features.

Background Spatial characteristics of sEMG signals are obtained by high-density matrix sEMG electrodes for further complex upper arm movement classification. Multiple electrode channels of the high-density sEMG acquisition device aggravate the burden of the microprocessor and deteriorate control system's real-time performance at the same time. A shoulder motion recognition optimization method based on the maximizing mutual information from multiclass CSP selected spatial feature channels and wavelet packet features extraction is proposed in this study. Results The relationship between the number of channels and recognition rate is obtained by the recognition optimization method. The original 64 electrodes channels are reduced to only 4-5 active signal channels with the accuracy over 92%. Conclusion The shoulder motion recognition optimization method is combined with the spatial-domain and time-frequency-domain features. In addition, the spatial feature channel selection is independent of feature extraction and classification algorithm. Therefore, it is more convenient to use less channels to achieve the desired classification accuracy.

Collagen density regulates the activity of tumor-infiltrating T cells

BackgroundTumor progression is accompanied by dramatic remodeling of the surrounding extracellular matrix leading to the formation of a tumor-specific ECM, which is often more collagen-rich and of increased stiffness. The altered ECM of the tumor supports cancer growth and metastasis, but it is unknown if this effect involves modulation of T cell activity. To investigate if a high-density tumor-specific ECM could influence the ability of T cells to kill cancer cells, we here studied how T cells respond to 3D culture in different collagen densities.MethodsT cells cultured in 3D conditions surrounded by a high or low collagen density were imaged using confocal fluorescent microscopy. The effects of the different collagen densities on T cell proliferation, survival, and differentiation were examined using flow cytometry. Cancer cell proliferation in similar 3D conditions was also measured. Triple-negative breast cancer specimens were analyzed for the number of infiltrating CD8+ T cells and for the collagen density. Whole-transcriptome analyses were applied to investigate in detail the effects of collagen density on T cells. Computational analyses were used to identify transcription factors involved in the collagen density-induced gene regulation. Observed changes were confirmed by qRT-PCR analysis.ResultsT cell proliferation was significantly reduced in a high-density matrix compared to a low-density matrix and prolonged culture in a high-density matrix led to a higher ratio of CD4+ to CD8+ T cells. The proliferation of cancer cells was unaffected by the surrounding collagen-density. Consistently, we observed a reduction in the number of infiltrating CD8+ T-cells in mammary tumors with high collagen-density indicating that collagen-density has a role in regulating T cell abundance in human breast cancer.Whole-transcriptome analysis of 3D-cultured T cells revealed that a high-density matrix induces downregulation of cytotoxic activity markers and upregulation of regulatory T cell markers. These transcriptional changes were predicted to involve autocrine TGF-β signaling and they were accompanied by an impaired ability of tumor-infiltrating T cells to kill autologous cancer cells.ConclusionsOur study identifies a new immune modulatory mechanism, which could be essential for suppression of T cell activity in the tumor microenvironment.

Age-related changes in the mitochondria of human mural granulosa cells.

What changes in the mitochondria of human mural granulosa cells (mGCs) with maternal aging? The mitochondrial membrane potential (MMP) and the ability of oxidative phosphorylation (OXPHOS) of mGCs declines with reproductive aging, accompanied with more abnormal mitochondria. Mitochondria play an important role in the dialogue between the mGCs and oocytes. However, the underlying mechanism of mitochondrial dysfunction in mGCs in aging is still poorly understood. In total, 149 infertile women underwent IVF in the ART Centre of the Chinese PLA General Hospital, China from September 2016 to May 2017. Two age groups were investigated: the young group (<38 years old) and the old group (≥38 years old). The mitochondrial ultrastructure of mGCs was observed by transmission electron microscopy, and real-time quantitative polymerase chain reaction was applied to quantify the mitochondrial DNA (mtDNA) copy number, 4977-bp deleted DNA and mRNA expression of mitochondrial ATP synthases ATP5A1 and ATP5I. MMP was detected by flow cytometry and fluorescence microscopy, respectively. Reactive oxygen species (ROS) was tested by flow cytometry. A luminometer was used to measure the ATP levels and western blot to analyse the OXPHOS complex. In the young group, mitochondria were mostly round or oval, with a few intact parallel tubular-vesicular cristae and homogenous matrix density, while elongated mitochondria were mainly observed in the old group, which had numerous cristae and more high-density matrix particles. Abnormal mitochondria were more common in aging women (P = 0.012). mtDNA relative copy number was positively correlated with maternal age (r = 0.294, P = 0.009) and we found no one with 4977-bp deleted mitochondria. JC-1 (dye used as an indicator of MMP) ratio in the old group was significantly lower than the young group (3.01 ± 0.21 vs 3.85 ± 0.27, P = 0.033). Intracellular ROS levels between the groups did not differ significantly (P = 0.191). The intracellular ATP level in the young group was 1.75-fold higher than that of the advanced-age group (7.17 ± 1.16 vs 4.15 ± 0.60, P = 0.025). The protein expression of ATP5A1, as one of five proteins of OXPHOS, decreased with aging (P < 0.001). ATP5A1 mRNA expression was negatively correlated with aging (r = -0.341, P = 0.012). The quantity of mGCs from some individual patient, especially an advanced-age individual, was small, which cannot meet the demands of all the detections. mGCs dysfunction with aging is mainly linked to impaired mitochondrial function, especially OXPHOS function. Improving the OXPHOS ability in mGCs should be the focus in resolving infertility among advanced age women and making mGCs the proper mitochondria donor cells in the autologous mitochondria transplantation to oocytes. This work was supported by the grants of the National High Technology Research and Development Program of China, 863 Program No. SS2015AA020402, and the Key Projects of Military Medical Research, No. BWS11J058. There were no competing interests.

Abstract A65: Topographical guidance of angiogenesis at an interface of collagen densities

Abstract Tumor vasculature is characterized by leaky, tortuous, and dilated blood vessels that create heterogeneous blood flow and diminish the transport of oxygen. Pioneered by Jain, an emerging cancer treatment strategy seeks to normalize tumor vasculature in order to increase the delivery and efficacy of therapeutics. Overexpression of vascular endothelial growth factor (VEGF) and other pro-angiogenic factors within the tumor microenvironment have been considerably investigated as the major contributing factor to abnormal tumor vasculature, but less is understood about the influence of the physical environment and the underlying molecular mechanisms. During tumor progression, increased extracellular matrix (ECM) deposition occurs resulting in mechanically heterogeneous tissue defined by local alterations in density. Such changes to ECM density and composition can significantly disrupt cell behaviors. Our previous work has demonstrated that the presence of an interface produces directional migration and net cell migration is a function of collagen matrix density. Here, we utilize a similar sequential polymerization technique to create a distinct low-to-high collagen density interface, in order to replicate the heterogeneity found in tumor tissue and investigate the role of tumor matrix mechanics in promoting abnormal tumor vasculature. Specifically, Human Umbilical Vein Endothelial Cells (HUVECs) were encapsulated in a low-density collagen matrix, cultured for three days until capillary-like networks were formed, and a second, high-density collagen matrix supplemented with VEGF and basic fibroblast growth factor (bFGF) was added to create a 3D interface. Angiogenesis across and capillary-like network organization at the collagen density interface was then evaluated by time-lapse microscopy and immunofluorescence. Preliminary data indicates that the presence of a low-to-high density interface increased HUVEC capillary-like network branching and length. We demonstrate that the number of branches per network, total number of branches, and total network length all increased as a function of the density interface, where the larger difference in density between the two regions produced more branching points and increased network length. Together, our data demonstrate how ECM heterogeneities, in the form of interfacial boundaries, affect capillary-like network architecture and promote abnormal branching. This work provides further insight into cellular sensing during tumor angiogenesis, as well as helps to identify novel methods for tumor vasculature normalization, as a means to improve the efficacy of many chemotherapeutic and radiation treatments. Citation Format: Matthew R. Zanotelli, Francois Bordeleau, Cynthia A. Reinhart-King. Topographical guidance of angiogenesis at an interface of collagen densities. [abstract]. In: Proceedings of the AACR Special Conference on Engineering and Physical Sciences in Oncology; 2016 Jun 25-28; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2017;77(2 Suppl):Abstract nr A65.

Recent developments in neutron imaging with applications for porous media research

Abstract. Computed tomography has become a routine method for probing processes in porous media, and the use of neutron imaging is especially suited to the study of the dynamics of hydrogenous fluids, and of fluids in a high-density matrix. In this paper we give an overview of recent developments in both instrumentation and methodology at the neutron imaging facilities NEUTRA and ICON at the Paul Scherrer Institut. Increased acquisition rates coupled to new reconstruction techniques improve the information output for fewer projection data, which leads to higher volume acquisition rates. Together, these developments yield significantly higher spatial and temporal resolutions, making it possible to capture finer details in the spatial distribution of the fluid, and to increase the acquisition rate of 3-D CT volumes. The ability to add a second imaging modality, e.g., X-ray tomography, further enhances the feature and process information that can be collected, and these features are ideal for dynamic experiments of fluid distribution in porous media. We demonstrate the performance for a selection of experiments carried out at our neutron imaging instruments.

Preparation of carbon/carbon composite by pyrolysis of ethanol and methane

A high textured carbon/carbon (C/C) composite was prepared using the mixture gas of ethanol and methane as the precursor by isothermal chemical vapor infiltration. The preform was infiltrated at 1180°C with the gas pressure from 2 to 10kPa. For 85h infiltration, the average bulk density is up to 1.8±0.02gcm−3. The texture of the infiltrated carbon was studied by polarized-light microscopy and characterized with the aid of the extinction angle. Texture and fracture morphology of the pyrolytic carbon matrix were observed using scanning electronic microscope. C/C composites with high textured pyrolytic carbon matrix and high density were obtained by pyrolysis of ethanol and methane. This indicates the mixture of ethanol and methane is a promising candidate of the precursors for the preparation of C/C composites.