Complex Interface Research Articles

Information system for carrying out vocational guidance work in schools of Ukraine

Problem. The problem for Ukrainian universities is the annual enrollment of students in the amount that allows the university to exist and fulfill its purpose. In the conditions of a significant decrease in the number of graduates in our country and an increase in the number of higher educational institutions, the competition among universities for entrants has sharply increased. Goal. It is necessary to create an information system to inform high school students throughout Ukraine about the existence of the Kharkiv National Automobile and Highway University, its specialties, opportunities, advantages, etc. Perhaps the consequence of such widespread information will be an increase in the number of applicants at our university. Methodology. When developing an information system for fast automatic sending of messages to many thousands of addresses of educational institutions of Ukraine of the III level of accreditation, it was impossible to rely on existing analogues, because such were not found in the information space. We used the method of synthesis of information systems on the technical task. Results. An information system has been developed for fast sending of messages to ten thousand addresses of educational institutions of the III level of accreditation. The developed information system searches for the corresponding addresses on the Internet and enters them into the computer database. The basis of the developed system is the database "Graduate of Ukraine", which contains the necessary information about almost all educational institutions with III level of accreditation. The algorithm of work of the developed information system and a kind of the interface of a software complex are resulted. In addition, many results of the system are presented: the created tables with data on educational institutions, the developed inquiries and reports, e-mails with invitations to the Open Doors Day. Originality. The developed system is an original development in Ukraine. No mention was found of an information system that creates and generates database tables and then uses them for programmed actions. Practical value. The developed information system is already used to provide students of graduation and other classes of all educational institutions of Ukraine of the III level of accreditation with information about our university; regarding the specialties offered by the university and the corresponding professions; regarding open days, preparatory courses and much more.

Nanomechanics serving polymer-based composite research

Tremendous progress in nanomechanical testing and modelling has been made during the last two decades. This progress emerged from different areas of materials science dealing with the mechanical behaviour of thin films and coatings, polymer blends, nanomaterials or microstructure constituents as well as from the rapidly growing field of MEMS. Nanomechanical test methods include, among others, nanoindentation, in-situ testing in a scanning or transmission electron microscope coupled with digital image correlation, atomic force microscopy with new advanced dynamic modes, micropillar compression or splitting, on-chip testing, or notched microbeam bending. These methods, when combined, reveal the elastic, plastic, creep, and fracture properties at the micro- and even the nanoscale. Modelling techniques including atomistic simulations and several coarse graining methods have been enriched to a level that allows treating complex size, interface or surface effects in a realistic way. Interestingly, the transfer of this paradigm to advanced long fibre-reinforced polymer composites has not been as intense compared to other fields. Here, we show that these methods put together can offer new perspectives for an improved characterisation of the response at the elementary fibre-matrix level, involving the interfaces and interphases. Yet, there are still many open issues left to resolve. In addition, this is the length scale, typically below 10 micrometres, at which the current multiscale modelling paradigm still requires enhancements to increase its predictive potential, in particular with respect to non-linear plasticity and fracture phenomena.

The slab–mantle wedge interface of an incipient subduction zone: Insights from the P–T–D evolution and petrological characteristics of the Dalrymple Amphibolite, Palawan Ophiolite, Philippines

AbstractIn this contribution, we present the petrological characteristics and pressure–temperature–deformation (P–T–D) history of the Dalrymple Amphibolite in Palawan Island, Philippines. This unit occurs below the residual mantle peridotites of the Palawan Ophiolite composed of interlayered dunite and harzburgite. The Dalrymple Amphibolite is predominantly composed of high‐grade metamafic blocks with minor metasedimentary units surrounded by a highly sheared hybridized matrix (kyanite + Ca‐amphibole + biotite + ilmenite ± garnet). Zr‐in‐rutile geothermometry and quartz‐in‐garnet geobarometry of the garnet amphibolite block reveal the P–T conditions of the prograde metamorphism from ~625°C, 11.5 kbar to ~700°C, 13 kbar. Zr‐in‐rutile geothermometer and the TZARS geobarometer (clinozoisite + rutile + quartz = anorthite + titanite + H2O) further indicate comparable peak metamorphic conditions for the amphibolite and epidote amphibolite (~605–710°C, 10–13 kbar) blocks. Geothermobarometry of the matrix surrounding the blocks reveals similar peak metamorphic conditions of ~700°C and 13 kbar to the garnet amphibolite blocks. The paleogeothermal gradient preserved in the Dalrymple Amphibolite (~16°C/km) and its block‐in‐matrix structure are atypical of metamorphic soles and are more akin to high‐T mélange complexes interpreted to have formed during incipient subduction. These P–T estimates and its block‐in‐matrix structure suggest that the Dalrymple Amphibolite likely represents the slab–mantle wedge interface of a young arc complex already transitioning from the much warmer paleogeothermal gradients of the slab–mantle wedge interface when subduction was first initiated. The similar peak metamorphic conditions constrained in the matrix and the metamafic blocks in the Dalrymple Amphibolite indicate that the matrix‐forming deformation started before the sequence reached peak metamorphic conditions at depths of around 45 km. Furthermore, the petrological and geochemical characteristics of this block‐in‐matrix sequence and the multiple generation of cross‐cutting veins reveal the complex processes that occur in the slab–mantle wedge interface of an arc in its infancy. Our results highlight the prevalence of Ca‐amphibole and kyanite over phyllosilicates (e.g., chlorite and serpentine) in the mélange matrix, mixing of crustal components along the slab–mantle wedge interface promoted by multiple deformation events and the ubiquity of fluids throughout its history. Subduction zones with similar geothermal gradients (e.g., warm subduction zones) possibly share these petrological characteristics.

A hybrid moment of fluid–level set framework for simulating primary atomization

This paper presents a hybrid moment of fluid–level set (HyMOFLS) method of liquid/gas interface reconstruction for the application to simulate primary atomization of liquid fuel. This method combines the moment of fluid (MOF) method and the level set framework in the coupled level set volume of fluid (CLSVOF) method. In this hybrid method, the MOF and CLSVOF methods are used to reconstruct the interface in the under-resolved and the resolved regions of the flow, respectively. An interface surface resolution metric called interface resolution quality (IRQ) is introduced to identify and classify these two flow regions in the computational domain. Such a strategy classifies/tags each computational cell with MOF or CLSVOF method based on a threshold value for the IRQ. The MOF method uses liquid volume fraction as well as centroids of liquid and gas phases for the interface reconstruction. The CLSVOF method uses the level set for describing the interface and liquid volume fraction for conserving the mass. The phase centroids in the HyMOFLS method are computed and transported on-the-fly during the cell tagging process. The transport of the liquid volume fraction, level set, and the phase centroids are performed using a directionally split algorithm. This algorithm is coupled with the Navier-Stokes equations solver that uses ghost fluid method as well as consistent mass and momentum flux computation for the momentum equation. Various numerical tests that exhaustively assess the capabilities, accuracy, and computational time consumption of the HyMOFLS method under multiple flow conditions and configurations are presented. The results from these tests suggest that this hybrid framework is capable of well capturing the liquid/gas interface belonging to thin and under-resolved structures that are often encountered in simulations of turbulent atomization of liquids. Following these tests, a detailed parametric study on the threshold value of IRQ is presented to test its effect on the accuracy of interface reconstruction. Finally, this hybrid framework is employed to simulate turbulent jet injection and pre-filming planar Airblast atomization cases of engineering applications. The proposed HyMOFLS method is found to achieve a good balance between the accuracy and the computational cost of reconstructing the liquid/gas interface for complex and turbulent atomization configurations.

A Novel Type of PD-L1 Inhibitor rU1 snRNPA From Human-Derived Protein Scaffolds Library.

Three marketed anti-PD-L1 antibodies almost have severe immune-mediated side effects. The therapeutic effects of anti-PD-L1 chemical inhibitors are not satisfied in the clinical trials. Here we constructed human-derived protein scaffolds library and screened scaffolds with a shape complementary to the PD-1 binding domain of PD-L1. The RNA binding domain of U1 snRNPA was selected as one of potential binders because it had the most favorable binding energies with PD-L1 and conformed to pre-established biological criteria for the screening of candidates. The recombinant U1 snRNPA (rU1 snRNPA) in Escherichia coli exhibits anti-cancer activity in melanoma and breast cancer by reactivating tumor-suppressed T cells in vitro and anti-melanoma activity in vivo. Considering hydrophobic and electrostatic interactions, three residues were mutated on the interface of U1 snRNPA and PD-L1 complex, and the ranked variants by PatchDock and A32D showed an increased active phenotype. The screening of human-derived protein scaffolds may become the potential development of therapeutic agents.

Termination of DNA replication at Tus-ter barriers results in under-replication of template DNA

The complete and accurate duplication of genomic information is vital to maintain genome stability in all domains of life. In Escherichia coli, replication termination, the final stage of the duplication process, is confined to the "replication fork trap" region by multiple unidirectional fork barriers formed by the binding of Tus protein to genomic ter sites. Termination typically occurs away from Tus-ter complexes, but they become part of the fork fusion process when a delay to one replisome allows the second replisome to travel more than halfway around the chromosome. In this instance, replisome progression is blocked at the nonpermissive interface of the Tus-ter complex, termination then occurs when a converging replisome meets the permissive interface. To investigate the consequences of replication fork fusion at Tus-ter complexes, we established a plasmid-based replication system where we could mimic the termination process at Tus-ter complexes invitro. We developed a termination mapping assay to measure leading strand replication fork progression and demonstrate that the DNA template is under-replicated by 15 to 24 bases when replication forks fuse at Tus-ter complexes. This gap could not be closed by the addition of lagging strand processing enzymes or by the inclusion of several helicases that promote DNA replication. Our results indicate that accurate fork fusion at Tus-ter barriers requires further enzymatic processing, highlighting large gaps that still exist in our understanding of the final stages of chromosome duplication and the evolutionary advantage of having a replication fork trap.

Setting the tone at the top: How the interface processes of organizational climate and non-TMT Managers' leadership transmit TMT cohesion to employees

We explore whether, and how, Top Management Team (TMT) cohesion can affect the collective turnover intentions of employees, through two interrelated interface processes. Based on Social Information Processing theory, we propose that the organization's corrosive climate and non-TMT managers' transformational leadership transmit TMT cohesion-based symbolic and relational information through a moderated-mediation model. The results of our Structural Equations Modelling (SEM) analyses of a multi-source dataset of 96 organizations—including 305 TMT members and 10964 employees split across three surveys—support our hypotheses. Confirmatory Factor Analyses support our measurement model, and the testing of various alternative models indicate that our findings are robust. Overall, our theory and findings highlight a more complex interface perspective on how the TMT affects employees, as key internal stakeholders, and provides a comprehensive model for future work.

Compound jetting from bubble bursting at an air-oil-water interface

Bursting of bubbles at a liquid surface is ubiquitous in a wide range of physical, biological, and geological phenomena, as a key source of aerosol droplets for mass transport across the interface. However, how a structurally complex interface, widely present in nature, mediates the bursting process remains largely unknown. Here, we document the bubble-bursting jet dynamics at an oil-covered aqueous surface, which typifies the sea surface microlayer as well as an oil spill on the ocean. The jet tip radius and velocity are altered with even a thin oil layer, and oily aerosol droplets are produced. We provide evidence that the coupling of oil spreading and cavity collapse dynamics results in a multi-phase jet and the follow-up droplet size change. The oil spreading influences the effective viscous damping, and scaling laws are proposed to quantify the jetting dynamics. Our study not only advances the fundamental understanding of bubble bursting dynamics, but also may shed light on the airborne transmission of organic matters in nature related to aerosol production.

Wakefield's Offspring

Wakefield's Offspring

H2O treatment-induced uniform NiOX interfacial layer boosting brightness and light-emitting efficiency of blue perovskite electroluminescence

The reported NiO x interfacial layers in blue perovskite light-emitting diodes (PeLEDs) usually require high-temperature annealing and complex interface modification. Herein, we report a kind of uniform NiO x anode interfacial layer induced by H 2 O treatment, which effectively enhances the brightness and light-emitting efficiency of blue PeLEDs simultaneously. Compared to the as-prepared NiO x anode interfacial layer, H 2 O treatment renders uniform and pinhole-free NiO x morphology. The solution-processed perovskite blue emissive layer prepared atop the H 2 O-treated NiO x interfacial layer demonstrates enhanced photoluminescent property and superior morphology with low trap density. The blue PeLEDs employing H 2 O-treated NiO x as anode interfacial layer show a maximum luminance of 9052 cd/m 2 and a maximum external quantum efficiency (EQE) of 1.80%, whereas the control device based on the as-prepared NiO x anode interfacial layer merely exhibits a maximum luminance of 3850 cd/m 2 and an EQE of 0.88%, leading to about 135% and 104% increase in brightness and efficiency, respectively. The PeLEDs emit pure blue light with emission peak located at 482 nm and demonstrate superior spectral stability under different driving voltages and operating time. • High-brightness blue PeLEDs were fabricated using NiO x interfacial layer. • H 2 O-treated NiO x interfacial layer induces to form high-quality blue perovskite emissive layer. • The blue PeLEDs attain a maximum luminance of 9052 cd/m 2 and a maximum EQE of 1.80%. • The PeLEDs emit stable blue light with emission peak at 482 nm.

Geometrical and electro-static determinants of protein-protein interactions.

Protein-protein interactions (PPI) are pivotal to the numerous processes in the cell. Therefore, it is of interest to document the analysis of these interactions in terms of binding sites, topology of the interacting structures and physiochemical properties of interacting interfaces and the of forces interactions. The interaction interface of obligatory protein-protein complexes differs from that of the transient interactions. We have created a large database of protein-protein interactions containing over100 thousand interfaces. The structural redundancy was eliminated to obtain a non-redundant database of over 2,265 interaction interfaces. Therefore, it is of interest to document the analysis of these interactions in terms of binding sites, topology of the interacting structures and physiochemical properties of interacting interfaces and the offorces interactions. The residue interaction propensity and all of the rest of the parametric scores converged to a statistical indistinguishable common sub-range and followed the similar distribution trends for all three classes of sequence-based classifications PPInS. This indicates that the principles of molecular recognition are dependent on the preciseness of the fit in the interaction interfaces. Thus, it reinforces the importance of geometrical and electrostatic complementarity as the main determinants for PPIs.

An attempt to predict spray characteristics at early stage of the atomization process by using surface density and curvature distribution

Nowadays, numerical simulations of atomization has reached a mature state through interface capturing approaches. With these approaches, the liquid–gas flow with its complex interface morphology can be precisely described but at the price of high mesh resolution, that makes these simulations very intensive in terms of computational cost. Practically, for most of the injection system, it is not possible to achieve a simulation up to a point where the spray formation is completed. Thus, there are several attempts based on the transformation of liquid elements such as ligaments, liquid sheet or other non-spherical to equivalent droplets. Overall, these approaches assumed that before the complete finalization of the atomization process the spray under formation carries enough information to be representative of the final spray. In this work, we have pushed this idea a step further by using global variables such as the liquid volume fraction and the surface density available in ELSA models to ensure the transports and the conservation of the main features of the spray. Then, the surface curvature distribution is analysed assuming that a part of the interface carries already curvatures that are relevant with respect to the final spray. A well-known academic test case representative of an aeronautical injection system and based on a planar prefilmer atomizer with a gas co-flow has been selected to evaluate our proposal. This configuration was studied both experimentally and numerically thanks to high-fidelity simulations. Our purpose has been to follow the already validated numerical approaches but with less computationally intensive simulations. Then, new analysis based on surface density and surface curvature distribution have been tested to recover spray characteristics and even the spray diameter distribution. It appears that these variables are meaningful even when there is no droplet yet formed, and thus they allow the description of the full atomization process from the early stage even on the liquid film. Finally, a procedure has been proposed where the spray is sufficiently atomized to reconstruct the diameter distribution from the curvature distribution. At our best knowledge, this last step is a first attempt on practical injection system. We have proposed a very simple method to detect which part of the interface carries the relevant curvature, thus obtaining a reconstructed diameter distribution that fit well with available experimental data. Although the proposed approach cannot be still considered universally applicable to any case, this preliminary assessment clearly shows its potential.

An efficient and accurate numerical method for the heat conduction problems of thermal metamaterials based on edge-based smoothed finite element method

Thermal metamaterials are a class of artificial composite structures with special thermal conduction properties. Due to the existence of complex multi-phase materials arrangement and interfaces in the thermal metamaterials, an efficient and accurate numerical method is on-demand to predict their temperature distribution and performances. In this paper, we studied the edge-based smoothed finite element method (ES-FEM) for simulating the heat conduction of thermal metamaterials in both steady-state and transient circumstances. Benefit from the adopted smoothing technique, the numerical errors caused by the complex interface are further eliminated. The most significant advantage of the proposed method is that one can directly use the automatically generated coarse triangle mesh to reduce the computational costs while ensuring accuracy. Two numerical examples are presented, in which two typical thermal metamaterials, the thermal cloak and thermal concentration device, are considered respectively in both steady-state and transient cases. The results illustrate that the ES-FEM based approach has good efficiency and accuracy in the heat conduction simulation of the thermal metamaterials.

(Invited) Multiscale Modeling and Theory Experiment Integration for Understanding Complex Interfaces in Materials for Hydrogen Production and Storage

Chemical processes occurring at solid-gas, solid-liquid, and solid-solid interfaces critically determine the performance and durability of hydrogen production and storage technologies. While probing behavior of these interfaces under operating conditions remains challenging, recent progress in predictive multiscale modeling methods together with high-fidelity experimental characterization has led to significant advancements in understanding how microscopic interfacial processes translate to macroscopic device behavior. In this talk, we will provide an overview of our materials modeling efforts within the DOE HydroGEN, HyMARC, and H2NEW hydrogen production and storage consortia, which span ab-initio atomistic modeling to macroscopic device modeling while leveraging state-of-art experimental characterization to ensure fidelity of interpretation. Concrete examples will be provided from our recent activities focused on identifying factors that dictate performance and durability of materials under operating conditions. In particular, we will discuss how computational models have helped to elucidate mechanisms of interface chemistry, formation of new phases, and the impact of interfaces on key reaction pathways that are intimately related to the device performance and durability. We will also illustrate how experimental characterization data has been incorporated to constrain the models and obtain new understanding of interfacial phenomena. Finally, we will discuss how the obtained knowledge may be used to develop strategies for improving materials used in hydrogen production and storage technologies. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Immunological Mechanisms of Metal Allergies and the Nickel-Specific TCR-pMHC Interface.

Besides having physiological functions and general toxic effects, many metal ions can cause allergic reactions in humans. We here review the immune events involved in the mediation of metal allergies. We focus on nickel (Ni), cobalt (Co) and palladium (Pd), because these allergens are among the most prevalent sensitizers (Ni, Co) and immediate neighbors in the periodic table of the chemical elements. Co-sensitization between Ni and the other two metals is frequent while the knowledge on a possible immunological cross-reactivity using in vivo and in vitro approaches remains limited. At the center of an allergic reaction lies the capability of a metal allergen to form T cell epitopes that are recognized by specific T cell receptors (TCR). Technological advances such as activation-induced marker assays and TCR high-throughput sequencing recently provided new insights into the interaction of Ni2+ with the αβ TCR-peptide-major histocompatibility complex (pMHC) interface. Ni2+ functionally binds to the TCR gene segment TRAV9-2 or a histidine in the complementarity determining region 3 (CDR3), the main antigen binding region. Thus, we overview known, newly identified and hypothesized mechanisms of metal-specific T cell activation and discuss current knowledge on cross-reactivity.

Application of a high-order MP scheme to computation of multi-phase flows with heat and mass transfer

Reliable prediction of unsteady multiphase flows with mass changes, large density ratios, and complex flow features is very challenging due to the need to accurately resolve both complex interface deformations and steep gradients associated with material interfaces. This paper describes an application of our recently developed high-order monotonicity preserving (MP) scheme – a reliable and robust scheme for long-term computations of flows contain complex smooth structures interspersed with discontinuities (Ha and Lee, 2020) − to the solution of unsteady incompressible two-phase flows in the presence of heat and mass changes. The flow is governed by the multiphase Navier–Stokes equations, which comprises of the mixture continuity equation, the mixture momentum equations, the mixture energy equation, and the continuity equation for the individual phase. The numerical discretization is implemented on generalized curvilinear grids for facilitating flow simulations of the complex geometries. Our high-order MP scheme is applied to the calculations of the convective and surface tension terms. To obtain an effectively simultaneous solution of all equations, a novel dual-time stepping approach in conjunction with an implicit Runge–Kutta three-stage scheme is proposed. The reliability of the proposed numerical algorithm is then examined for a 1D Stefan condensation problem and two condensing flows including single bubble and steam-jet condensation problems. Particularly, for the single bubble condensation test, the bubble characteristics at different time instants are evaluated both qualitatively and quantitatively. For the steam-jet condensation test, the capability for capturing the evolution of interface deformations under different thermal and hydrodynamic flow conditions is highlighted. Finally, the effects of subcooling degree and steam mass flow rate on heat and mass transfer characteristics are investigated and discussed.

Solution NMR Spectroscopy for Characterizing Protein-Glycosaminoglycan Interactions.

Solution nuclear magnetic resonance (NMR) spectroscopy and, in particular, chemical shift perturbation (CSP) titration experiments are ideally suited for mapping and characterizing the binding interface of macromolecular complexes. 1H-15N-HSQC-based CSP studies have become the method of choice due to their simplicity, short-time requirements, and minimal working knowledge of NMR. CSP studies for characterizing protein-glycosaminoglycan (GAG) interactions can be challenging due to binding-induced aggregation/precipitation and/or poor quality data. In this chapter, we discuss how optimizing experimental conditions such as protein concentration, choice of buffer pH, ionic strength, and GAG size, as well as sensitivity of NMR instrumentation can overcome these roadblocks to obtain meaningful structural insights into protein-GAG interactions.

Molecular modeling and rational design of noncovalent halogen⋯oxygen⋯hydrogen motif at the complex interface of EGFR kinase domain with RALT peptide

Epidermal growth factor receptor (EGFR) of ErbB tyrosine kinase is involved in the pathogenesis and progression of diverse carcinoma types. The receptor-associated late transducer (RALT) is an endogenous feedback inhibitor of EGFR by competitively disrupting the kinase dimerization event through its fragment 1 (fgt1). In the present study, the intermolecular interaction of EGFR kinase domain with RALT fgt1 was investigated to rationally design a noncovalent halogen⋯oxygen⋯hydrogen motif across the interaction interface, which consists of a halogen bond between the kinase and fgt1-derived peptide as well as a hydrogen bond in the kinase that share a common carbonyl oxygen acceptor. The halogen types and substitution positions were systematically optimized to determine their best combination involved in the noncovalent motif. A cooperative effect was observed between the halogen bond and hydrogen bond, suggesting that the whole noncovalent motif is a holonomic system that can work together to promote the kinase–peptide binding.

Structural Characterization of Degrader-Induced Ternary Complexes Using Hydrogen-Deuterium Exchange Mass Spectrometry and Computational Modeling: Implications for Structure-Based Design.

The field of targeted protein degradation (TPD) has grown exponentially over the past decade with the goal of developing therapies that mark proteins for destruction leveraging the ubiquitin-proteasome system. One common approach to achieve TPD is to employ a heterobifunctional molecule, termed as a degrader, to recruit the protein target of interest to the E3 ligase machinery. The resultant generation of an intermediary ternary complex (target-degrader-ligase) is pivotal in the degradation process. Understanding the ternary complex geometry offers valuable insight into selectivity, catalytic efficiency, linker chemistry, and rational degrader design. In this study, we utilize hydrogen-deuterium exchange mass spectrometry (HDX-MS) to identify degrader-induced protein-protein interfaces. We then use these data in conjunction with constrained protein docking to build three-dimensional models of the ternary complex. The approach was used to characterize complex formation between the E3 ligase CRBN and the first bromodomain of BRD4, a prominent oncology target. We show marked differences in the ternary complexes formed in solution based on distinct patterns of deuterium uptake for two degraders, CFT-1297 and dBET6. CFT-1297, which exhibited positive cooperativity, altered the deuterium uptake profile revealing the degrader-induced protein-protein interface of the ternary complex. For CFT-1297, the ternary complexes generated by the highest scoring HDX-constrained docking models differ markedly from those observed in the published crystal structures. These results highlight the potential utility of HDX-MS to provide rapidly accessible structural insights into degrader-induced protein-protein interfaces in solution. They further suggest that degrader ternary complexes exhibit significant conformation flexibility and that biologically relevant complexes may well not exhibit the largest interaction surfaces between proteins. Taken together, the results indicate that methods capable of incorporating linker conformation uncertainty may prove an important component in degrader design moving forward. In addition, the development of scoring functions modified to handle interfaces with no evolved complementarity, for example, through consideration of high levels of water infiltration, may prove valuable. Furthermore, the use of crystal structures as validation tools for novel degrader methods needs to be considered with caution.

The Role of the Thalamus in Declarative and Procedural Linguistic Memory Processes.

Typically, thalamic aphasias appear to be primarily lexical-semantic disorders representing difficulty using stored declarative memories for semantic information to access lexical word forms. Yet, there also is reason to believe that the thalamus might play a role in linguistic procedural memory. For more than two decades, we have known that basal ganglia dysfunction is associated with difficulties in procedural learning, and specific thalamic nuclei are the final waypoint back to the cortex in cortico-basal ganglia-cortical loops. Recent analyses of the role of the thalamus in lexical-semantic processes and of the role of the basal ganglia in linguistic processes suggest that thalamic participation is not simply a matter of declarative vs. procedural memory, but a matter of how the thalamus participates in lexical-semantic processes and in linguistic procedural memory, as well as the interaction of these processes. One role for the thalamus in accessing lexical forms for semantic concepts relates to the stabilization of a very complex semantic-lexical interface with thousands of representations on both sides of the interface. Further, the possibility is discussed that the thalamus, through its participation in basal ganglia loops, participates in two linguistic procedural memory processes: syntactic/grammatical procedures and procedures for finding words to represent semantic concepts, with the latter interacting intricately with declarative memories. These concepts are discussed in detail along with complexities that can be addressed by future research.