Interstitial Movement Research Articles

Paesaggi dell’interstizio. Per un Illuminismo post-coloniale

The landscape of tomorrow can be imagined today starting from events currently emerging from what Michel Foucault called “the interstice”. According to him, the interstice is the gray area that lies between the fundamental choices and exclusion’s strategies that every culture accomplishes to affirm its identity. Some of these interstices have been brought to light precisely in the context of landscape theories, notably by Gilles Clément. Others, however, are now emerging in political fields where landscape is not the object of a theory, but a reference for struggle and contestation. Thus, starting from a visit to the 2024 Venice Art Biennale, this essay outlines the intertwining between some interstitial movements of today - post-colonial studies, migrations, queer identities - and their impact on a possible landscape to come: not identitarian but fluid, inclusive and open towards a new idea of cosmopolitism.

Abstract 2952: Predicting concentration of PARP inhibitors in human tumor tissue using PBPK modeling

Abstract Poly (ADP-ribose) polymerase (PARP) inhibitors exert their effect intracellularly within tumor, thus sufficient tumor penetration is essential for a pharmacological response. Preclinical mouse xenograft data show a 3.3-fold higher tumor versus plasma exposure of niraparib, while for olaparib tumor exposure was less than plasma. This study aimed to build a physiologically-based pharmacokinetic (PBPK) model extended with a tissue composition-based permeability-limited tumor model to: (a) gain a mechanistic understanding of the differences in tumor exposure of niraparib and olaparib; and (b) to predict clinical tumor exposure in ovarian cancer patients at clinically relevant dosing regimens. A permeability-limited tumor model was developed that integrates data on tumor composition and drug physicochemical properties analogous to the established permeability-limited organ model available for the liver in the Simcyp Simulator [1,2]. The model assumes that unbound unionized drug is in equilibrium between the vascular and interstitial compartments and movement of the drug between the interstitial and intracellular space is via passive permeability. Total tumor concentration is dependent on passive permeability of the drug, drug binding to PARP and nonspecific binding to neutral lipids, neutral phospholipids, and acidic phospholipids in the intracellular space, albumin in the interstitial and pH of the tumor interstitial and intracellular spaces. Clinical and preclinical tumor physiological parameters such as volume, blood flow, and tissue composition are defined using published data. The model was developed using the Simcyp Simulator V17.1 and R [3]. Consistent with preclinical data, the model predicts a 5-7-fold higher tumor exposure relative to plasma, as measured by the AUC tumor to plasma ratio of niraparib compared with olaparib. Significant binding to acidic phospholipids contributes to the increased tumor exposure to niraparib, a basic drug, a mechanism that is not relevant to the neutral drug olaparib. Ongoing work aims to extrapolate the model to predict the clinical tumor concentration of olaparib and niraparib in ovarian cancer patients and to investigate the sensitivity of the model to key tumor attributes, including blood flow and interstitial pH that may contribute to variability in tumor drug exposure. A similar modeling approach may be used to predict the tumor exposure of other small molecule anticancer drugs from their plasma concentration and physicochemical properties in different types of solid tumor. References Jamei M et al, Clin Pharmacokinet. 2014;53:73-87 Poulin P et al, J Pharm Sci. 2015;104:1508-21 R Core Team (2018). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL https://www.R-project.org/. Citation Format: Rachel H. Rose, Kaiming Sun, Linzhong Li, Keyur Gada, Jing Yu Wang, Yongchang Qiu. Predicting concentration of PARP inhibitors in human tumor tissue using PBPK modeling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2952.

Embodying Alternatives to Capitalism in the 21st Century

The goal of this article is twofold. First, to illustrate how in the last decade a growing number of critical and Marxist thinkers committed to discussing and developing theories of change have started to broaden their focus by including social movements and grassroots initiatives that are “interstitial”, i.e. initiatives that are developing within capitalism and are striving to prefigure a post-capitalist society in the here and now without engaging in contentious, violent and revolutionary actions and activities. To achieve this, I mainly focus on the work of four authors: Erik Olin Wright, John Holloway, Ana C. Dinerstein, and Luke Martell. The second goal of this article is to understand why these interstitial movements are getting so much attention from critical scholars and to argue that the time is ripe for establishing a theory of (and for) prefigurative social movements. The article closes with some brief reflections on the future of radical thinking that includes an invitation, directed mostly at the young generation of critical and Marxist scholars, to begin a dialogue with theories of change developed within other disciplines, to engage with activists, and to experiment with participatory methods and techniques.

The effect of injected interstitials on void formation in self-ion irradiated nickel containing concentrated solid solution alloys

Pure nickel and three nickel containing single-phase concentrated solid solution alloys (SP-CSAs) have been irradiated using 3 MeV Ni2+ ions at 500°C to fluences of 1.5×1016 and 5.0×1016cm−2. The radiation-induced voids were characterized using cross sectional transmission electron microscopy that distributions of voids and dislocation loops were presented as a function of depth. A various degree of void suppression was observed on the tested samples and a defect clusters migration mechanism was proposed for NiCo. In order to sufficiently understand the defect dynamics in these SP-CSAs, the injected interstitial effect has been taken into account along with the 1-dimentional (1-D) and 3-dimentional (3-D) interstitial movement mechanisms.

A theoretical study on the elastic deformation of cellular phase and creation of necrosis due to the convection reaction process inside a spherical tumor

Several biological processes, such as convective nutrient transport and convective drug delivery in biological tissues involves the transvascular and interstitial movement of biofluids. This work addresses transvascular and interstitial transport of nutrient inside a spherical tumor. Most of the biological tissues behave like deformable porous material and show mechanical behavior towards the fluid motion, due to the fact, that the forces like the drag, which is associated with fluid flow may compress the tissue material. On the macroscopic level, transport of solutes like nutrients, drug molecules, etc. within the tumor interstitial space is modeled. The hydrodynamic problem is treated with biphasic mixture theory under steady state and spherically symmetry situation. The transvascular transport of nutrient is modeled with the modified Sterling’s equation. The present model describes the overall nutrient distribution and predicts various criteria for the necrosis formation inside the tumor. Present study justifies that the parameters, which controls the nutrient supply to the tumor interstitial space through the blood vessel network inside the tumor, competes with reversible nutrient consumption kinetics of the tumor cells. This study also finds the role of some of those parameters on the deformation of cellular phase of the tumor as a consequence of interstitial fluid flow.

Microenvironmental Control of High-Speed Interstitial T Cell Migration in the Lymph Node

T cells are highly concentrated in the lymph node (LN) paracortex, which serves an important role in triggering adoptive immune responses. Live imaging using two-photon laser scanning microscopy revealed vigorous and non-directional T cell migration within this area at average velocity of more than 10 μm/min. Active interstitial T cell movement is considered to be crucial for scanning large numbers of dendritic cells (DCs) to find rare cognate antigens. However, the mechanism by which T cells achieve such high-speed movement in a densely packed, dynamic tissue environment is not fully understood. Several new findings suggest that fibroblastic reticular cells (FRCs) and DCs control T cell movement in a multilateral manner. Chemokines and lysophosphatidic acid produced by FRCs cooperatively promote the migration, while DCs facilitate LFA-1-dependent motility via expression of ICAM-1. Furthermore, the highly dense and confined microenvironment likely plays a key role in anchorage-independent motility. We propose that T cells dynamically switch between two motility modes; anchorage-dependent and -independent manners. Unique tissue microenvironment and characteristic migration modality of T cells cooperatively generate high-speed interstitial movement in the LN.

Interaction between oxygen interstitials and deformation twins in alpha-titanium

Twinning is an important deformation mechanism in many hexagonal close packed metals, including α-titanium (Ti) alloys. However, the mechanisms for twin nucleation, growth, and interaction with other defects are not completely understood. In this study we interrogate the behavior of oxygen (O) interstitials near a (101¯2) twin boundary using a combination of density functional theory (DFT) and modified embedded atom method (MEAM) calculations. The presence of the twin boundary significantly affects both interstitial formation energy as well as the activation barriers for diffusion between sites. We demonstrate that a tetrahedral interstitial is stable in the twin boundary, despite being unstable in bulk Ti, while the formation energies of the octahedral, hexahedral, and crowdion interstitials are all modified by a nearby twin. Further, the activation barriers for diffusion in the region near the twin are uniformly lower than in the bulk. An atom diffusing across the twin boundary moves through several paths with peak energies more than 0.3 eV lower than for comparable diffusion far from the twin, suggesting that the (101¯2) twin is a fast diffusion pathway and movement of oxygen interstitials across the twin during twin growth is possible.

Interstitial Movements in the Works of Hanada Kiyoteru: A Preliminary Study

This is a study of Hanada Kiyoteru, a communist literary and art critic whose position in the world of postwar art criticism has gone relatively unexamined in Japanese studies and art history in English. One of the more aggressive critical figures during the immediate postwar era, he helped to foster a community of art critics and artists who carried into practice aspects of his dialectical and surrealist-inflected method of reading. He was in many ways responsible for signifying how postwar avant-garde art should be read, as well as how the prewar efforts could be revived to continue the leftist struggle. This article is primarily concerned with his earlier work, starting from his first collection of essays, Spirit of Renaissance (1946), to his well-known Avant-Garde Art (1954), touching upon some of his major motifs found in these texts. Beginning with Hanada's concern for the “transformative age” referred to as tenkeiki, the article examines his dynamic thinking process, which mirrored the very performative maneuvers he saw in the figures who occupied a transitional period. His investment in the historical interstice was a way to escape essentialism, humanism, and ultimately, Japan. He did so in order to conceive of plurality, nonhuman agency, and becoming. This article, rather than to place Hanada in the historical context in which he wrote, treats his work aesthetically, paying particular attention to the rhythmic and agile movement of his writing and thought.

A review of recent findings about stress-relaxation in the respiratory system tissues.

This article reviews the state of the art about an unclear physiological phenomenon interesting respiratory system tissues, i.e., stress-relaxation. Due to their visco-elastic properties, the tissues do not maintain constant stress under constant deformation. Rather, the stress slowly relaxes and falls to a lower value. The exact molecular basis of this complex visco-elastic behavior is not well defined, but it has been suggested that it may be generated because of the anisotropic mechanical properties of elastin and collagen fibers in the alveolar septa and their interaction phenomena, such as reciprocal sliding, also in relation to interstitial liquid movements. The effects on stress-relaxation of various biochemical and physical factors are reviewed, including the consequences of body temperature variations, respiratory system inflammations and hyperbaric oxygen exposure, endocrinal factors, circulating blood volume variations, changes in inflation volume and/or flow, changes in intra-abdominal pressure because of pneumoperitoneum or Trendelenburg position. The effects of these factors on stress-relaxation have practical consequences because, depending on visco-elastic pressure amount which is requested to inflate the respiratory system in different conditions, respiratory muscles have to produce different values of inspiratory pressure during spontaneous breathing. High inspiratory pressure values might increase the risk of respiratory failure development on mechanical basis.

Interstitial movement and emergence of barbel Barbus barbus free embryos and larvae

The movement of barbel Barbus barbus free embryos in the interstitial zone and the timing of larval emergence were studied for 12 days in an artificial stream. After egg fertilization (day 1), hatching occurred on day 6, downstream interstitial movements of free embryos on day 9 and emergence and downstream movement of all larvae on day 12, with density of free embryos decreasing as day of emergence approached. The results suggest that a memory-based response of B. barbus to environmental conditions, previously observed in 0+ year juveniles, begins at an early age.

Dosimetric Impact of Inter-Fraction Variation in Interstitial HDR Brachytherapy

Background: Patient setup errors in External Beam Radiotherapy (EBRT) are minimized to a great extent, due to recent technological developments but in contrary brachytherapy received least attention in inter-fraction catheter movement and its impact in dose delivery. This article deals with inter-fraction interstitial catheter movement and its impact in dose delivery to the target. An attempt is made to study the dosimetric impact of this variation. Objectives: The objective of the study is to evaluate the inter-fraction variation in the position of implanted interstitial applicators and to assess the dosimetric impact in interstitial High Dose Rate (HDR) brachytherapy. Materials and Methods: 55 patients treated for carcinoma tongue, breast, buccal mucosa, cervix, floor of mouth and soft tissue sarcoma over a period of 2 years (December 2011-May 2013) were considered. All the patients underwent CT scan on the next day of the implant and 3D planning was done either by Eclipse or Oncentra Master plan Treatment Planning System (TPS). Patients were treated by HDR brachytherapy remote after-loading units, either by Gamma Med iX plus or Microselectron. At the end of the last fraction, CT scan was repeated and re-planning done. The variation in position of the implanted applicators/catheters and its impact on dosimetric parameters were evaluated and analyzed. Results: The range of positional displacement of the interstitial catheters ranges from 4.5 mm to 6.8 mm. The maximum variation in prescribed dose to D90 of Clinical Target Volume was 10.88%. Conclusions: If the total duration of interstitial implant of HDR brachytherapy extends for more than a week from the day of imaging, it is recommended to do CT imaging and re-plan again. It is mandatory to suture the buttons of the implant to the skin. Edema and movement of organs (e.g., tongue) are the main cause for the positional variation of the catheters.

Structural control of ionic conductivity in LiAlSi2O6 and LiAlSi4O10 glasses and single crystals

Abstract In order to better understand the mechanisms of lithium dynamics and to elucidate the influence of defects in lithium mobility, we have studied the Li-ion propagation through natural single crystals of α-spodumene, LiAlSi2O6 and petalite, LiAlSi4O10 using impedance spectroscopy. Electrical conductivity in petalite and α-spodumene is 4–5 orders of magnitude lower than in glasses of the same composition, and three orders of magnitude lower than in synthetic β-spodumene. Conductivity in α-spodumene is anisotropic with conductivity along the c-axis being 0.3–0.4 log units higher than perpendicular to the c-axis. Contrary to α-spodumene, isotropic conductivity was observed for petalite single crystals. Despite the large difference in conductivity values, the activation energies for ionic conduction of α-spodumene along the c-axis (74 to 86 kJ/mol) are only slightly higher than for LiAlSi2O6 and LiAlSi4O10 glasses (∼67 kJ/mol). On the other hand, much higher activation energies of 112–134 kJ/mol were determined for petalite. Based on our investigation, a vacancy-controlled transport mechanism is indicated for the densely packed α-spodumene structure, while in the open framework structure of petalite formation and movement of Li interstitials is proposed to be dominant mechanism for charge transfer.

Localization and movement of native interstitials in chlorinated SrCl2:Fe crystals

The formation of the electron trapped Fe+(IV) centre, produced by X-ray irradiation at 80 K and further annealing at temperatures of up to 700 K in chlorinated SrCl2:Fe crystals, has been investigated by Electron Paramagnetic Resonance. Our studies report the transformation of the monoclinic Fe+(III) centre into the axial Fe+(IV) centre above 450 K. The formation of the Fe+(IV) centre is attributed to the presence and thermally activated movement of neighbouring interstitial chlorine and alkali impurity Na+ ions. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A central role for DOCK2 during interstitial lymphocyte motility and sphingosine-1-phosphate–mediated egress

Recent observations using multiphoton intravital microscopy (MP-IVM) have uncovered an unexpectedly high lymphocyte motility within peripheral lymph nodes (PLNs). Lymphocyte-expressed intracellular signaling molecules governing interstitial movement remain largely unknown. Here, we used MP-IVM of murine PLNs to examine interstitial motility of lymphocytes lacking the Rac guanine exchange factor DOCK2 and phosphoinositide-3-kinase (PI3K)γ, signaling molecules that act downstream of G protein–coupled receptors, including chemokine receptors (CKRs). T and B cells lacking DOCK2 alone or DOCK2 and PI3Kγ displayed markedly reduced motility inside T cell area and B cell follicle, respectively. Lack of PI3Kγ alone had no effect on migration velocity but resulted in increased turning angles of T cells. As lymphocyte egress from PLNs requires the sphingosine-1-phosphate (S1P) receptor 1, a Gαi protein–coupled receptor similar to CKR, we further analyzed whether DOCK2 and PI3Kγ contributed to S1P-triggered signaling events. S1P-induced cell migration was significantly reduced in T and B cells lacking DOCK2, whereas T cell–expressed PI3Kγ contributed to F-actin polymerization and protein kinase B phosphorylation but not migration. These findings correlated with delayed lymphocyte egress from PLNs in the absence of DOCK2 but not PI3Kγ, and a markedly reduced cell motility of DOCK2-deficient T cells in close proximity to efferent lymphatic vessels. In summary, our data support a central role for DOCK2, and to a lesser extent T cell–expressed PI3Kγ, for signal transduction during interstitial lymphocyte migration and S1P-mediated egress.

Electron-trapping centers and interstitials in chlorinatedSrCl2:Fesingle crystals

Electron-trapped ${\mathrm{Fe}}^{+}$-type centers, produced by x-ray irradiation at $80\phantom{\rule{0.3em}{0ex}}\mathrm{K}$ and further annealing at higher temperatures in iron-doped ${\mathrm{SrCl}}_{2}$ single crystals grown in chlorine gas, have been investigated by electron paramagnetic resonance. The ${\mathrm{Fe}}^{+}(\mathrm{III})$ and ${\mathrm{Fe}}^{+}(\mathrm{IIIa})$ centers, produced by annealing at temperatures higher than $200\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, exhibit monoclinic local symmetry with the two $\stackrel{⃡}{g}$- tensor principal axes situated in the (110) plane slightly tilted away from the [001] and [1--10] directions, respectively. The ${\mathrm{Fe}}^{+}(\mathrm{IV})$ center, observed after several cycles of irradiation and annealing to $700\phantom{\rule{0.3em}{0ex}}\mathrm{K}$, exhibits tetragonal local symmetry around $⟨100⟩$ and a well-resolved four-component structure, attributed to the superhyperfine interaction with a neighboring monovalent impurity ion. The presence and properties of the low symmetry radiation-induced ${\mathrm{Fe}}^{+}$ paramagnetic centers are attributed to trapping and the thermally activated movement of chlorine interstitials. Both precursor ${\mathrm{Fe}}^{2+}$ and resulting ${\mathrm{Fe}}^{+}$ centers are perturbed by these interstitials, which are introduced in ${\mathrm{SrCl}}_{2}:\mathrm{Fe}$ crystals during growth under a chlorine atmosphere.

Thermally stimulated currents as a measure of degradation of zinc oxide varistors

ZnO varistor degradation phenomena was studied using thermally stimulated current (TSC) method. It is believed that asymmetrical degradation of V-I characteristics caused by DC biasing is due to charge accumulation on the reverse biased side of ZnO grain barrier. The TSCs' measuring system and cryostat apparatus used in experiment were described. The thermally stimulated currents observed in this study for varistor samples doped with different amounts of Co, due to their recovery from asymmetrical electric stress, could not be controlled by movement of Zn interstitials with activation energy 0.55 v eV, as it is widely believed, for the TSC activation energy determined in this experiment was 0.39 v eV.

Suppression of reverse-short-channel effect insub –0.1 µm n -MOSFETs with Sb S/D implantation

A study is presented into the reverse-short-channel effect (RSCE) for Sb S/D ion implantation at 10 keV. A high impurity concentration is found to reduce interstitial movement in the channel, which restricts the level RSCE at short-channel lengths. The interstitials can be healed by thermal treatment at 850°C directly after ion implantation, resulting in the suppression of the RSCE.

Point defects and their clusters in f.c.c. metals studied by computer simulations

Extensive theoretical and experimental studies of vacancies and interstitials in f.c.c. metals have been carried out at the University of Illinois since 1950. In the present work, the studies of molecular dynamics are carried out by computer simulation in order to explore the detailed atomistic process of dynamical movement of point defects of vacancies and interstitials, and their clustering in f.c.c. metals. An isotropic EAM potential due to Daw and Baskes ([itPhys. Rev. B, 29 (1984) 6443) was utilized to calculate the force which acts on atoms in a crystal. Calculations were carried out for Cu, Ag, Au, Ni and Al. The first part of the results of this paper describes the vacancies and their clusters. The importance of the migration of small vacancy clusters is emphasized. The atomistic growth step of vacancy clusters is also described. In the second part, the results of interstitials and their clusters are summarized. The small interstitial clusters relax to a bundle of parallel 〈110〉 crowdions which moves with the very small migration energy of 0.001 eV. The simulation of the movement of interstitials in Au at very low temperature was carried out. The movement of interstitial clusters is sensitively responsive on the strain field.

Solute segregation in dilute bcc alloys under irradiation

Abstract Computer models for the prediction of solute segregation in alloys under irradiation require expressions for the diffusion coefficients which appear in the generalized Fick equations used in these models. These expressions are obtained by analyses of atomic transport caused by the movement of vacancies and interstitials generated by the radiation. The present paper provides expressions for the required diffusion coefficients (ten in number) in terms of the properties of atomic models which are appropriate for many bcc transition metals including α-Fe.

A molecular dynamics study of displacement cascades in α-iron

The mechanisms of defect production in displacement cascades in α-iron have been investigated by computer simulation. Cascades of up to 5 keV in energy have been simulated by molecular dynamics in crystals with atomic interactions described by a many-body potential. The effects of lattice temperature have been studied by using block temperatures of either 100 or 600 K. 80 cascades have been modelled overall. The morphology of cascades during the collisional phase changes at about 1–2 keV, due to the collective nature of atomic displacements at higher energy. This transition is reflected in the relaxation time during the subsequent recombination phase, and it also decreases the efficiency factor for defect production. This factor is similar in size to that obtained from recent modelling of copper, an fcc metal. Although the cascade zone contains a large number of displaced atoms, true melting was not observed in α-Fe, and vacancy clustering did not occur in the thermal spike phase. Interstitial clustering has been analysed, and found to be less pronounced than in copper. One large cluster was observed to grow by interstitial movement during the thermal spike, and visual analysis has shown that it formed a perfect dislocation loop: it was not nucleated by the Eyre-Bullough mechanism, however. Statistics on the cascade parameters are presented, and comparisons with work on other crystal structures are drawn where possible.