bluuebunny/crossref_metadata_2025 huggingface dataset:
Spatiotemporal Structure of Nonlinear Subunits in Macaque Visual Cortex
Authors: Pack Christopher C. , Conway Bevil R. , Born Richard T. , Livingstone Margaret S.
Published: January 2006

The primate visual system is arranged hierarchically, starting from the retina and continuing through a series of extrastriate visual areas. Selectivity for motion is first found in individual neurons in the primate visual cortex (V1), in which many simple cells respond selectively to the direction and speed of moving stimuli. Beyond simple cells, most studies of direction selectivity have focused on either V1 complex cells or neurons in the middle temporal area (MT/V5). To understand how visual information is transferred along this pathway, we have studied all three types of neurons, using a reverse correlation procedure to obtain high spatial and temporal resolution maps of activity for different motion stimuli. Most complex and MT cells showed strong second-order interactions, indicating that they were tuned for particular displacements of an apparent motion stimulus. The spatiotemporal structure of these interactions showed a high degree of similarity between the populations of V1 complex cells and MT cells, in terms of the spatiotemporal limits and preferences for motion and their two-dimensional spatial structure. Much of the structure in the V1 and MT second-order kernels could be accounted for on the basis of the first-order responses of V1 simple cells, under the assumption of a Reichardt or motion-energy type of computation.
Temporal Structure in Zebra Finch Song: Implications for Motor Coding
Authors: Glaze Christopher M. , Troyer Todd W.
Published: January 2006

Adult zebra finch songs consist of stereotyped sequences of syllables. Although some behavioral and physiological data suggest that songs are structured hierarchically, there is also evidence that they are driven by nonhierarchical, clock-like bursting in the premotor nucleus HVC (used as a proper name). In this study, we developed a semiautomated template-matching algorithm to identify repeated sequences of syllables and a modified dynamic time-warping algorithm to make fine-grained measurements of the temporal structure of song. We find that changes in song length are expressed across the song as a whole rather than resulting from an accumulation of independent variance during singing. Song length changes systematically over the course of a day and is related to the general level of bird activity as well as the presence of a female. The data also show patterns of variability that suggest distinct mechanisms underlying syllable and gap lengths: as tempo varies, syllables stretch and compress proportionally less than gaps, whereas syllable–syllable and gap–gap correlations are significantly stronger than syllable–gap correlations. There is also increased temporal variability at motif boundaries and especially strong positive correlations between the same syllables sung in different motifs. Finally, we find evidence that syllable onsets may have a special role in aligning syllables with global song structure. Generally, the timing data support a hierarchical view in which song is composed of smaller syllable-based units and provide a rich set of constraints for interpreting the results of physiological recordings.
A Neural Correlate of Stochastic Echo Imaging
Authors: Firzlaff Uwe , Schörnich Sven , Hoffmann Susanne , Schuller Gerd , Wiegrebe Lutz
Published: January 2006

Bats quickly navigate through a highly structured environment relying on echolocation. Large natural objects in the environment, like bushes or trees, produce complex stochastic echoes, which can be characterized by the echo roughness. Previous work has shown that bats can use echo roughness to classify the stochastic properties of natural objects. This study provides both psychophysical and electrophysiological data to identify a neural correlate of statistical echo analysis in the batPhyllostomus discolor. Psychophysical results show that the bats require a fixed minimum roughness of 2.5 (in units of base 10 logarithm of the stimulus fourth moment) for roughness discrimination. Electrophysiological results reveal a subpopulation of 15 of 94 recorded cortical units, located in an anterior region of auditory cortex, whose rate responses changed significantly with echo roughness. It is shown that the behavioral ability to discriminate differences in the statistics of complex echoes can be quantitatively predicted by the neural responses of this subpopulation of auditory-cortical neurons.
Traumatic Injury and the Presence of Antigen Differentially Contribute to T-Cell Recruitment in the CNS
Authors: Ling Changying , Sandor Matyas , Suresh M. , Fabry Zsuzsa
Published: January 2006

T-cell recruitment into the brain is critical in inflammatory and autoimmune diseases of the CNS. We use intracerebral antigen microinjection and tetramer technology to track antigen-specific CD8+T-cells in the CNS and to clarify the contribution of antigen deposition or traumatic injury to the accumulation of T-cells in the brain. We demonstrate that, after intracerebral microinjection of ovalbumin, ovalbumin-specific CD8+T-cells expand systemically and then migrate into the brain where they complete additional proliferation cycles. T-cells in the brain are activated and respond toin vitrosecondary antigen challenge. CD8+T-cells accumulate and persist in sites of antigen in the brain without replenishment from the periphery. Persistent survival of CD8+T-cells at sites of cognate antigen is significantly reduced by blocking CD154 molecules. A small traumatic injury itself does not lead to recruitment of CD8+T-cells into the brain but attracts activated antigen-specific CD8+T-cells from cognate antigen injection sites. This process is presumably antigen independent and cannot be inhibited by blocking CD154 molecules. These data show that activated antigen-specific CD8+T-cells accumulate in the CNS at both cognate antigen-containing and traumatic injury sites after intracerebral antigen delivery. The accumulation of activated antigen-specific T-cells at traumatic injury sites, in addition to antigen-containing areas, could amplify local inflammatory processes in the CNS. Combination therapies in neuroinflammatory diseases to block both of these processes should be considered.
Morphine and Pain-Related Stimuli Enhance Cell Surface Availability of Somatic δ-Opioid Receptors in Rat Dorsal Root Ganglia
Authors: Gendron Louis , Lucido Anna Lisa , Mennicken Françoise , O'Donnell Dajan , Vincent Jean-Pierre , Stroh Thomas , Beaudet Alain
Published: January 2006

The present study demonstrates that perikaryalδ-opioid receptors (δORs) in rat dorsal root ganglion (DRG) neurons bind and internalize opioid ligands circulating in the CSF. Using confocal and electron microscopy, we found that prolonged morphine treatment increased the cell surface density of these perikaryal δORs and, by way of consequence, receptor-mediated internalization of the fluorescent deltorphin (DLT) analog ω-Bodipy 576/589 deltorphin-I 5-aminopentylamide (Fluo-DLT) in all three types of DRG neurons (small, medium, and large). In contrast, chronic inflammatory pain induced by the injection of complete Freund's adjuvant (CFA) into one hindpaw selectively increased Fluo-DLT internalization in small and medium-sized DRG neurons ipsilateral to the inflammation. Based on our previous studies in the spinal cord of μ-opioid receptor (μOR) knock-out mice, it may be assumed that the enhanced membrane recruitment of δORs observed after sustained morphine is attributable to stimulation of μORs. However, the selectivity of the effect induced by inflammatory pain suggests that it involves a different mechanism, namely a modality-specific and pain-related activation of C and Aδ fibers. Indeed, stimulation by capsaicin of transient receptor potential vanilloid 1 receptors, which are selectively expressed by small diameter (< 600 μm2) DRG neurons, increased Fluo-DLT internalization exclusively in this cell population. The present results, therefore, demonstrate that DRG neurons express perikaryal δORs accessible to CSF-circulating ligands and that the density and, hence, presumably also the responsiveness, of these receptors may be modulated by both pain-related stimuli and sustained exposure to μOR agonists.
In VivoImaging of Preferential Motor Axon Outgrowth to and Synaptogenesis at Prepatterned Acetylcholine Receptor Clusters in Embryonic Zebrafish Skeletal Muscle
Authors: Panzer Jessica A. , Song Yuanquan , Balice-Gordon Rita J.
Published: January 2006

Little is known about the spatial and temporal dynamics of presynaptic and postsynaptic specializations that culminate in synaptogenesis. Here, we imaged presynaptic vesicle clusters in motor axons and postsynaptic acetylcholine receptor (AChR) clusters in embryonic zebrafish to study the earliest events in synaptogenesisin vivo. Prepatterned AChR clusters are present on muscle fibers in advance of motor axon outgrowth from the spinal cord. Motor axon growth cones and filopodia are selectively extended toward and contact prepatterned AChR clusters, followed by the rapid clustering of presynaptic vesicles and insertion of additional AChRs, hallmarks of synaptogenesis. All initially formed neuromuscular synapses contain AChRs that were inserted into the membrane at the time the prepattern is present. Examination of embryos in which AChRs were blocked or clustering is absent showed that neither receptor activity or receptor protein is required for these events to occur. Thus, during initial synaptogenesis, postsynaptic differentiation precedes presynaptic differentiation, and prepatterned neurotransmitter clusters mark sites destined for synapse formation.
The Role of Striatum in Initiation and Execution of Learned Action Sequences in Rats
Authors: Bailey Kathleen R. , Mair Robert G.
Published: January 2006

To understand the role of striatum in motor sequence learning, we trained rats to perform a series of tasks measuring speed and accuracy of responding to luminance cues presented as discriminative stimuli for single nose pokes or for sequences of nose pokes in a serial reaction time task. Habit (stimulus–response) learning was measured by comparing performances when stimuli were repeated (predictable) with when they were selected randomly (unpredictable). Sequences had defined start and end points and were limited to five nose pokes to minimize chunking. When sequences were repeated, response time (RT) increased for nose pokes initiating the sequence and decreased for nose pokes completing it. These effects developed incrementally across sessions, consistent with the time course of habit learning. Medial (mCPu), lateral, and complete (CPu) caudate–putamen lesions affected speed and accuracy of single nose poke responses, confirming the role of these areas in guiding responses with external sensory stimuli. None of these lesions affected the short-term increase in accuracy observed when single nose poke responses were repeated. Both mCPu and CPu lesions increased RTs for initiating sequential responses, effects that were exacerbated across sessions in which specific sequences were repeated. None of the lesions affected the gradual decrease in RT for nose pokes completing repeated sequences. Correlational analyses confirmed the relationship between the extent of dorsal striatal damage and the ability to respond to brief luminance cues and to initiate learned sequences. These results provide evidence implicating dorsal striatum in higher-level organizational aspects of learning reflected in planning that precedes the execution of learned action sequences.
Mitochondrial Encephalomyopathy inDrosophila
Authors: Celotto Alicia M. , Frank Adam C. , McGrath Steven W. , Fergestad Tim , Van Voorhies Wayne A. , Buttle Karolyn F. , Mannella Carmen A. , Palladino Michael J.
Published: January 2006

Mitochondrial encephalomyopathies are common and devastating multisystem genetic disorders characterized by neuromuscular dysfunction and tissue degeneration. Point mutations in the human mitochondrialATP6gene are known to cause several related mitochondrial disorders: NARP (neuropathy, ataxia, and retinitis pigmentosa), MILS (maternally inherited Leigh's syndrome), and FBSN (familial bilateral striatal necrosis). We identified a pathogenic mutation in theDrosophilamitochondrialATP6gene that causes progressive, adult-onset neuromuscular dysfunction and myodegeneration. Our results demonstrate ultrastructural defects in the mitochondrial innermembrane, neural dysfunction, and a marked reduction in mitochondrial ATP synthase activity associated with this mutation. ThisDrosophilamutant recapitulates key features of the human neuromuscular disorders enabling detailedin vivostudies of these enigmatic diseases.
A Signaling Mechanism from Gαq-Protein-Coupled Metabotropic Glutamate Receptors to Gene Expression: Role of the c-Jun N-Terminal Kinase Pathway
Authors: Yang Lu , Mao Limin , Chen Hai , Catavsan Michael , Kozinn Jonathan , Arora Anish , Liu Xianyu , Wang John Q.
Published: January 2006

Gαq-protein-coupled group I metabotropic glutamate receptors (mGluRs) are densely expressed in brain neurons and are actively involved in various cellular activities. In this study, we investigated the role of group I mGluRs in regulating the c-Jun N-terminal kinase (JNK)/stress-activated protein kinase in cultured neurons. We found that selective activation of mGluR5 induced a rapid and transient phosphorylation of JNK. In a series of studies to determine the mechanisms, we found that the conventional mGluR5-associated signaling pathways (inositol-1,4,5-triphosphate-mediated Ca2+release and activation of protein kinase C) were not involved in the mGluR5 regulation. Instead, ligand stimulation of mGluR5 caused a dynamic transactivation of the epidermal growth factor (EGF) receptor, which in turn triggered a downstream signaling pathway to upregulate JNK phosphorylation. Furthermore, the mGluR5-dependent JNK activation specifically activated c-Jun, but not activating transcription factor-2 or JunD, and increased activator protein-1 (AP-1)-mediated endogenous transcriptional activity. Together, we identified a novel mGluR5-to-nucleus communication through the EGF/JNK pathway, which functions to regulate AP-1-mediated transcription.
Reversal of Neuronal Migration in a Mouse Model of Fetal Alcohol Syndrome by Controlling Second-Messenger Signalings
Authors: Kumada Tatsuro , Lakshmana Madepalli K. , Komuro Hitoshi
Published: January 2006

The brains of fetal alcohol syndrome patients exhibit impaired neuronal migration, but little is known about the mechanisms underlying this abnormality. Here we show that Ca2+signaling and cyclic nucleotide signaling are the central targets of alcohol action in neuronal cell migration. Acute administration of ethanol reduced the frequency of transient Ca2+elevations in migrating neurons and cGMP levels and increased cAMP levels. Experimental manipulations of these second-messenger pathways, through stimulating Ca2+and cGMP signaling or inhibiting cAMP signaling, completely reversed the action of ethanol on neuronal migrationin vitroas well asin vivo. Each second messenger has multiple but distinct downstream targets, including Ca2+/calmodulin-dependent protein kinase II, calcineurin, protein phosphatase 1, Rho GTPase, mitogen-activated protein kinase, and phosphoinositide 3-kinase. These results demonstrate that the aberrant migration of immature neurons in the fetal brain caused by maternal alcohol consumption may be corrected by controlling the activity of these second-messenger pathways.
Multimodale Gerätekooperation basierend auf expliziten Zielen: Konzepte & Potentiale (Multimodal Appliance Cooperation based on Explicit Goals: Concepts & Potentials)
Authors: Giersich Martin , Heider Thomas , Kirste Thomas
Published: January 2006

Smart Environments werden sich zunehmend aus individuellen Komponenten (Smart Appliances) zusammensetzen, die sich selbst in ein schlüssig agierendes Ensemble einbetten müssen. Das erfordert Softwaretechnologien, die es den Geräten ermöglichen, mit Blick auf die Nutzerbedürfnisse spontan zu kooperieren. In diesem Beitrag werden wir erläutern, warum ein zielbasierter Ansatz sinnvoll ist, wie explizite Ziele genutzt werden können, systemweite Strategien zu finden und wie explizit deklarative Ziele als Maßstab für die Bewertung des Systemdesigns dienen können.
Ontologiebasiertes Engineering kontextadaptiver Webanwendungen (Ontology-based Engineering of Context-adaptive Web Applications)
Authors: Kaltz J. Wolfgang , Lohmann Steffen , Lang Eike , Hussein Tim , Ziegler Jürgen
Published: January 2006

Angesichts des zunehmenden Leistungsumfangs moderner Informations- und Kommunikationstechnologien und einer wachsenden Informationsflut in globalen Netzen werden Methoden und Mechanismen benötigt, die den Nutzern dem jeweiligen Nutzungskontext angepasste Informationen und Dienste liefern. In diesem Beitrag wird eine ontologiebasierte Methodik vorgestellt, die die Integration von Context Engineering-Mechanismen in den Entwicklungsprozess von Webanwendungen zum Ziel hat. Anschließend wird anhand einer Architektur für kontextadaptive Webanwendungen erläutert, wie sich durch diese Vorgehensweise Kontextanpassungen auf unterschiedlichen Ebenen bewirken lassen.
Strukturierte verankerte Diskussion als Form kooperativen Lernens mit eLectures (Structured Anchored Discussion as a Means of Collaborative Learning with eLectures)
Authors: Trahasch Stephan , Lauer Tobias
Published: January 2006

Vorlesungsaufzeichnungen als Lerninhalte bieten relativ eingeschränkte Möglichkeiten für kooperatives Lernen. Dieser Beitrag beschreibt das Konzept der skriptgesteuerten verankerten Diskussion, um netzbasierte Gruppendiskussion auf der Basis von eLectures zu unterstützen. Bei diesem Ansatz werden die Diskussionsbeiträge räumlich und zeitlich an den für den Beitrag relevanten Teilen von eLectures verankert, so dass für jeden Beitrag der inhaltliche Kontext ersichtlich ist. Zudem unterstützen Beitragstypisierung und Prompts eine strukturierte Diskussion gemäß einem vorgegebenen Kooperationsskript.
A Multistate Model for the Fluorescence Response of R‐Phycoerythrin
Authors: Gaigalas A. , Gallagher T. , Cole K. D. , Singh T. , Wang Lili , Zhang Yu‐Zhong
Published: January 2006

Although strong fluorescence makes the R‐phycoerythrin (R‐PE) proteins increasingly useful in biological and clinical assays, they are subject to nonlinear effects including transitions to collective dark states and photodegradation, which complicate quantitative applications. We report measurements of R‐PE fluorescence intensity as a function of incident power, duration of illumination and temperature. Emission intensity in the band at 570 nm is proportional to incident power for low power levels. At higher incident power, the emission at 570 nm is smaller than expected from a linear dependence on power. We propose that R‐PE undergoes both reversible emission cessation on a millisecond time scale attributed to transitions to a collective dark state, and irreversible photodegradation on a time scale of minutes. Singlet oxygen scavengers such as dithiothreitol and n‐propyl gallate have protective effects against the latter effect but not the former. Electrophoretic analysis of irradiated solutions of R‐PE indicates that significant noncovalent aggregation is correlated with photodegradation. A multistate model based on fluorescence measurements and geometric analysis is proposed for the fluorophores in R‐PE. The phycobilin fluorophores are partitioned into three groups: the phycourobilins (PUB) absorbing at 490 nm, one group of phycoerythobilins (PEB) absorbing at 530 nm (PEB‐530) and another group of PEB absorbing at 560 nm (PEB‐560). The two processes that result in the loss of fluorescence intensity are most likely associated with the PEB‐560 group.
Determination of the Minimum Temperature Required for Selective Photothermal Destruction of Cancer Cells with the Use of Immunotargeted Gold Nanoparticles
Authors: Huang Xiaohua , Jain Prashant K. , El‐Sayed Ivan H. , El‐Sayed Mostafa A.
Published: January 2006

Laser photothermal therapy of cancer with the use of gold nanoparticles immunotargeted to molecular markers on the cell surface has been shown to he an effective modality to selectively kill cancer cells at much lower laser powers than those needed for healthy cells. To elucidate the minimum light dosimetry required to induce cell death, photothermal destruction of two cancerous cell lines and a noncancerous cell line treated with antiepidermal growth factor receptor (anti‐EGFR) antibody‐conjugated gold nanoparticles is studied, and a numerical heat transport model is used to estimate the local temperature rise within the cells as a result of the laser heating of the gold nanoparticles. It is found that cell samples with higher nanoparticle loading require a lower incident laser power to achieve a certain temperature rise. Numerically estimated temperatures of 70–80°C achieved by heating the gold particles agree well with the measured threshold temperature for destruction of the cell lines by oven heating and those measured in an earlier nanoshell method. Specific binding of anti‐EGFR antibody to cancerous cells overexpressing EGFR selectively increases the gold nanoparticle loading within cancerous cells, thus allowing the cancerous cells to be destroyed at lower laser power thresholds than needed for the noncancerous cells. in addition, photothermal therapy using gold nanoparticles requires lower laser power thresholds than therapies using conventional dyes due to the much higher absorption coefficient of the gold nanoparticles.
Microsatellites Reveal Population Substructure of Klickitat River Native Steelhead and Genetic Divergence from an Introduced Stock
Authors: Narum Shawn R. , Powell Madison S. , Evenson Rolf , Sharp Bill , Talbot AndréJ.
Published: January 2006

Determining fine-scale genetic diversity and structure is critical for the conservation and management of populations, especially those under heavy anthropogenic influence. We analyzed 446 individuals at nine microsatellite loci to determine the local population structure of naturally produced steelhead Oncorhynchus mykiss and genetic differentiation from introduced hatchery strain steelhead in the Klickitat River of the Pacific Northwest. We detected significant genetic structure among steelhead in various tributaries to the Klickitat River; the most divergent population was located above a waterfall that acts as a partial upstream migration barrier (average pairwise FST = 0.13; P < 0.0001). Analysis of mixtures indicated an estimate of six to seven genetically distinct populations of naturally reproducing steelhead in this river system. The hatchery strain appears to remain genetically distinguishable from native stocks (average pairwise FST of 0.078 with P < 0.0001), as only 4.0% of naturally produced steelhead had their most likely assignment to the hatchery strain. These results indicate that the genetic integrity and variation of native Klickitat River steelhead have been maintained despite repeated hatchery introductions and that the potential is high for restoring this threatened population. Further, this study suggests that hierarchical analyses of mixtures to identify distinct populations in a watershed are a valuable method for directing management of reproductively isolated populations.
Effects of Sediment Cover on Survival and Development of White Sturgeon Embryos
Authors: Kock Tobias J. , Congleton James L. , Anders Paul J.
Published: January 2006

A simple, inexpensive apparatus (embryo incubation unit (EIU)) was developed and used to assess the relationship between sediment cover (Kootenai River sediments, 97% by weight in the 0.83-mm- to 1.0-mm-diameter range) and survival of white sturgeon Acipenser transmontanus embryos in the laboratory. An apparatus-testing trial assessed the effects of two sediment depths (5 and 20 mm), three EIU ventilation hole sizes (4.8, 6.8, and 9.5 mm) providing three levels of intrasediment flow, and EIU location (upstream or downstream in laboratory troughs) on embryo survival at two above-substrate flow velocities (0.05 and 0.15 m/s). A second trial assessed the effects of sediment cover duration (5-mm sediment cover for 4, 7, 9, 11, or 14 d, with a ventilation hole size of 9.5 mm and a flow velocity of 0.17 m/s) on mean embryo survival and larval length and weight. In the apparatus-testing trial, embryo survival was reduced (P < 0.0001) to 0–5% under sediment covers of either 5 or 20 mm in both the higher-flow and lower-flow troughs; survival in control EIUs without sediments exceeded 80%. Survival was not significantly affected by ventilation hole size but was weakly affected by EIU location. In the second trial, embryo survival was negatively correlated (P = 0.001) with increasing duration of sediment cover and was significantly higher for embryos covered for 4 d (50% survival) or 7 d (30% survival) than for those covered for 9, 11, or 14 d (15–20% survival). Sediment cover also delayed hatch timing (P < 0.0001) and decreased mean larval length (P < 0.0001). Our results suggest that sediment cover may be an important early life stage mortality factor in rivers where white sturgeon spawn over fine-sediment substrates.
The importance of plankton and nekton distributions in Ordovician palaeogeographical reconstructions
Authors: Servais Thomas , Blieck Alain , Caridroit Martial , Chen Xu , Paris Florentin , Tortello M. Franco
Published: January 2006

Trilobites and brachiopods are the two main fossil groups that allowed construction of the first palaeogeographical maps for the early Palaeozoic. Together with the bivalves and ostracodes, the benthic elements of these fossil groups have proved to be of great palaeobiogeographical importance. For this reason, these groups are usually considered to be ‘better’ fossils for inferring Ordovician palaeogeography. The present study indicates that planktic and nektic fossil groups should not be neglected in such palaeobiogeographical studies. The plotting on a palaeogeographical reconstruction for the Arenig (Lower Ordovician, – 480 Ma) of some planktic (acritarchs, chitinozoans) and nektic (vertebrates, pelagic trilobites) fossil groups indicates that their distribution appears in part surprisingly similar to that of the benthic trilobite faunas that are considered to display the greatest provincialism. For example, the distribution of the ‘peri-Gondwanan’ acritarch province including Arbusculidium filamentosum, Coryphidium and Striatotheca, and the distribution of the Eremochitina brevis chitinozoan assemblage are almost identical to the palaeogeographical distribution of the Calymenacean-Dalmanitacean trilobite fauna. A review of the different planktic and nektic fossil groups also indicates that it is very important to carefully select ‘good’ palaeogeographical indicators, in most cases from a large number of taxa. It appears that almost all fossil groups include some ‘good’ palaeobiogeographical ‘markers’. Therefore it is important to search for ‘better’ taxa within each fossil group, instead of looking only for the ‘better’ fossil groups as a whole.
Hospital and Physician Group Practice Participation in Prior and Next-Generation Value-Based Payment Programs
Authors: Kang So-Yeon , Anderson Gerard
Published: February 2024

This cohort study examines whether prior direct or indirect participation in the Centers for Medicare & Medicaid Innovation Bundled Payments for Care Improvement (BCPI) Initiative was associated with their participation in the next generation of the program.
Treating Adolescent Opioid Use Disorder in Primary Care
Authors: Hadland Scott E. , Burr William H. , Zoucha Kenneth , Somberg Chloe A. , Camenga Deepa R.
Published: February 2024

This survey study explores primary care pediatricians’ preparedness to counsel and treat adolescents with opioid use disorder (OUD) and perceived barriers to prescribing OUD medications.
Preparation and Performance Study of Titanium‐Based Nanocomposites in Selective Laser Melting: Microstructure Regulation and Optimization of Mechanical Properties
Authors: Shi Xiaojie , Wu Meiping , Lu Peipei , Ye Xiu
Published: February 2024

This study focuses on exploring the application of selective laser melting (SLM) technology in the preparation of titanium‐based nanocomposite materials. By introducing 0.5 wt% graphene oxide (GO) and 7.0% nanomolybdenum (Mo) powder, an attempt is made to improve the microstructure and mechanical properties of titanium alloy materials. The experimental results indicate that the microstructure of the titanium‐based nanocomposite material undergoes significant crystal refinement and phase transition behavior, suggesting a positive role of introducing nanoreinforcing phases in crystal structure regulation. Simultaneously, the introduction of GO significantly improves the thermal conductivity of the material, contributing to more uniform energy transfer and temperature distribution, thereby optimizing the process control of laser melting. In terms of mechanical performance, through microhardness and tensile performance tests, the microhardness of TC4–0.5GO–7Mo increases by ≈30.8% compared with pure TC4. This strengthening effect is primarily attributed to the uniform distribution of GO and Mo powder in the matrix, effectively hindering lattice slip and dislocation movement, enhancing the hardness and tensile properties of the material. Through a comprehensive analysis of microstructure and mechanical properties, not only the mapping relationship between the microstructure and mechanical properties of titanium‐based nanocomposite materials is clarified but also the strengthening mechanism is revealed.
MXene‐Based Energy Devices: From Progressive to Prospective
Authors: Kazim Samrana , Huang Chun , Hemasiri Naveen Harindu , Kulkarni Ashish , Mathur Sanjay , Ahmad Shahzada
Published: February 2024

Every once in a while, a revolutionary technological development arises, which leads to a significant change in the way to approach research and push development efforts. The appetite for new technology compels society to look for game‐changing materials, that can transform the industry and make advances. Sustainable energy production is paramount to addressing the climate crisis, and energy generation and storage play an important role in the development of self‐powered microelectronic devices. The 2D materials, MXenes have emerged as promising candidates for energy and other applications owing to their inherent electrical merits, high specific surface area, and tunable properties. Particularly, in the context of additive and interfacial materials for perovskite solar cell fabrication and utilization as additives in secondary batteries, this review delves into the application of MXenes in such devices. The protocols of MXenes and their nanostructures tailoring toward such applications and, the underlying mechanism is uncovered. Further, the existing challenges and direction for future in MXene‐based energy harvesters are discussed.
Recent Advances in Nanomedicine for Ocular Fundus Neovascularization Disease Management
Authors: Zhou Yifan , Xu Mingyu , Shen Wenyue , Xu Yufeng , Shao An , Xu Peifang , Yao Ke , Han Haijie , Ye Juan
Published: February 2024

As an indispensable part of the human sensory system, visual acuity may be impaired and even develop into irreversible blindness due to various ocular pathologies. Among ocular diseases, fundus neovascularization diseases (FNDs) are prominent etiologies of visual impairment worldwide. Intravitreal injection of anti‐vascular endothelial growth factor drugs remains the primary therapy but is hurdled by common complications and incomplete potency. To renovate the current therapeutic modalities, nanomedicine emerged as the times required, which is endowed with advanced capabilities, able to fulfill the effective ocular fundus drug delivery and achieve precise drug release control, thus further improving the therapeutic effect. This review provides a comprehensive summary of advances in nanomedicine for FND management from state‐of‐the‐art studies. First, the current therapeutic modalities for FNDs are thoroughly introduced, focusing on the key challenges of ocular fundus drug delivery. Second, nanocarriers are comprehensively reviewed for ocular posterior drug delivery based on the nanostructures: polymer‐based nanocarriers, lipid‐based nanocarriers, and inorganic nanoparticles. Thirdly, the characteristics of the fundus microenvironment, their pathological changes during FNDs, and corresponding strategies for constructing smart nanocarriers are elaborated. Furthermore, the challenges and prospects of nanomedicine for FND management are thoroughly discussed.
Octadecyl Gallate and Lipid‐Modified MnSe2 Nanoparticles Enhance Radiosensitivity in Esophageal Squamous Cell Carcinoma and Promote Radioprotection in Normal Tissues
Authors: Li Xinyue , Liu He , Gao Wenyan , Yang Qi , Li Xin , Zhou Xuantong , Wang Longwei , Lu Zhihao , Liu Jing , Luo Aiping , Chen Chunying , Liu Zhihua , Zhao YuLiang
Published: February 2024

Radiotherapy, a widely used therapeutic strategy for esophageal squamous cell carcinoma (ESCC), is always limited by radioresistance of tumor tissues and side‐effects on normal tissues. Herein, a signature based on four core genes of cyclic GMP‐AMP synthase‐stimulator of interferon genes (cGAS‐STING) pathway, is developed to predict prognosis and assess immune cell infiltration, indicating that the cGAS‐STING pathway and radiotherapy efficacy are closely intertwined in ESCC. A novel lipid‐modified manganese diselenide nanoparticle (MnSe2‐lipid) with extraordinarily uniform sphere morphology and tumor microenvironment (TME) responsiveness is developed to simultaneously overcome radioresistance and reduce side‐effects of radiation. The uniform MnSe2 encapsulated lipid effectively achieves tumor accumulation. Octadecyl gallate on surface of MnSe2 forming pH‐responsive metal–phenolic covalent realizes rapid degradation in TME. The released Mn2+ promotes radiosensitivity by generating reactive oxygen species induced by Fenton‐like reaction and activating cGAS‐STING pathway. Spontaneously, selenium strengthens immune response by promoting secretion of cytokines and increasing white blood cells, and performs antioxidant activity to reduce side‐effects of radiotherapy. Overall, this multifunctional remedy which is responsive to TME is capable of providing radiosensitivity by cGAS‐STING pathway‐mediated immunostimulation and chemodynamic therapy, and radioprotection of normal tissues, is highlighted here to optimize ESCC treatment.
Extreme Thermal Insulation and Tradeoff of Thermal Transport Mechanisms between Graphene and WS2 Monolayers
Authors: Zhang Ruiling , Gan Lin , Zhang Danyang , Sun Hao , Li Yongzhuo , Ning Cun‐Zheng
Published: February 2024

Controlling and understanding the heat flow at a nanometer scale are challenging, but important for fundamental science and applications. Two‐dimensional (2D) layered materials provide perhaps the ultimate solution for meeting these challenges. While there have been reports of low thermal conductivities (several mW m−1 K−1) across the 2D heterostructures, phonon‐dominant thermal transport remains strong due to the nearly‐ideal contact between the layers. Here, this work experimentally explores the heat transport mechanisms by increasing the interlayer distance from perfect contact to a few nanometers and demonstrates that the phonon‐dominated thermal conductivity across the WS2/graphene interface decreases further with the increasing interlayer distance until the air‐dominated thermal conductivity increases again. This work finds that the resulting tradeoff of the two heat conduction mechanisms leads to the existence of a minimum thermal conductivity at 2.11 nm of 1.41 × 10−5 W m−1 K−1, which is two thousandths of the smallest value reported previously. This work provides an effective methodology for engineering thermal insulation structures and understanding heat transport at the ultimate small scales.
Rational Design of New Conjugated Polymers with Main Chain Chirality for Efficient Optoelectronic Devices: Carbo[6]Helicene and Indacenodithiophene Copolymers as Model Compounds
Authors: Gedeon Clement , Del Rio Natalia , Furlan Francesco , Taddeucci Andrea , Vanthuyne Nicolas , Gregoriou Vasilis G. , Fuchter Matthew J. , Siligardi Giuliano , Gasparini Nicola , Crassous Jeanne , Chochos Christos L.
Published: February 2024

The unique properties of conjugated polymers (CPs) in various optoelectronic applications are mainly attributed to their different self‐assembly processes and superstructures. Various methods are utilized to tune and control CP structure and properties with less attention paid to the use of chirality. CPs with main chain chirality are rare and their microscopic and macroscopic properties are still unknown. In this work, the first experimental results are provided along these lines by synthesizing a series of racemic and enantiopure CPs containing statistical and alternating carbo[6]helicene and indacenodithiophene moieties and evaluating their microscopic (optical, energy levels) and macroscopic properties (hole mobilities, photovoltaic performance). It is demonstrated that a small statistical insertion of either the racemic or enantiopure helicene into the polymer backbone finely tunes the microscopic and macroscopic properties as a function of the statistical content. The microscopic properties of the enantiopure versus the racemic polymers with the same helicene loading remain similar. On the contrary, the macroscopic properties, and more interestingly those between the two enantiomeric forms, are altered as a function of the statistical content. Once incorporated into a solar cell device, these chiral CPs display better performance in their enantiopure versus racemic forms.
One‐Pot Production of Vanillin from Capsaicinoids through a Retrosynthetic Enzyme Cascade
Authors: Kim Hong‐Gon , Jang Youngho , Shin Jong‐Shik
Published: February 2024

Vanillin is a key organoleptic component in vanilla, one of the most important natural flavors in the industry. The limited supply of natural vanilla, extracted from cured vanilla beans, elevates the commercial value of ‘natural’‐labeled vanillin, producible by microbial conversion of natural precursors such as ferulic acid, eugenol, isoeugenol, lignin, and glucose. However, cellular toxicity and undesirable overoxidation of vanillin remain challenges to the microbial methods. Here, we developed a one‐pot enzymatic conversion of capsaicinoids to vanillin by retracing the biosynthetic pathway found in Capsicum plants. The enzyme cascade consists of the hydrolysis of capsaicinoids by immobilized lipase B from Candida antarctica (CALB) and the oxidative deamination of the resulting vanillylamine by ω‐transaminase from Paracoccus denitrificans (PDTA). Process optimization of individual enzyme reactions was conducted on an analytical scale, enabling>95% reaction yield of vanillin from capsaicinoids in the one‐pot cascade reaction without undesirable accumulation of the oxidation byproduct and the inhibitory reaction intermediate, i. e., vanillic acid and vanillylamine, respectively. To verify practical applicability, we performed a preparative‐scale reaction starting with 1.75 g capsaicinoids and 2.75 g sodium pyruvate at 10 mg/mL CALB and 3 μM PDTA, leading to an 81% reaction yield and a 57% isolation yield. This study is, to the best of our knowledge, the first demonstration of one‐pot production of vanillin from capsaicinoids, which might pave the way for cost‐effective and sustainable access to natural‐labeled vanillin from a renewable feedstock readily available from Capsicum fruits.
Poly(Glutamic Acid‐Lysine) Hydrogels with Alternating Sequence Resist the Foreign Body Response in Rodents and Non‐Human Primates
Authors: Zhou Xianchi , Cao Wenzhong , Chen Yongcheng , Zhu Zihao , Chen Yifeng , Ni Yanwen , Liu Zuolong , Jia Fan , Lu Zhouyu , Ye Yang , Han Haijie , Yao Ke , Liu Weifeng , Wei Xinyue , Chen Shengfu , Wang Youxiang , Ji Jian , Zhang Peng
Published: February 2024

The foreign body response (FBR) to implanted biomaterials and biomedical devices can severely impede their functionality and even lead to failure. The discovery of effective anti‐FBR materials remains a formidable challenge. Inspire by the enrichment of glutamic acid (E) and lysine (K) residues on human protein surfaces, a class of zwitterionic polypeptide (ZIP) hydrogels with alternating E and K sequences to mitigate the FBR is prepared. When subcutaneously implanted, the ZIP hydrogels caused minimal inflammation after 2 weeks and no obvious collagen capsulation after 6 months in mice. Importantly, these hydrogels effectively resisted the FBR in non‐human primate models for at least 2 months. In addition, the enzymatic degradability of the gel can be controlled by adjusting the crosslinking degree or the optical isomerism of amino acid monomers. The long‐term FBR resistance and controlled degradability of ZIP hydrogels open up new possibilities for a broad range of biomedical applications.
Large‐Scale, Mechanically Robust, Solvent‐Resistant, and Antioxidant MXene‐Based Composites for Reliable Long‐Term Infrared Stealth
Authors: Guo Bi‐Fan , Wang Ye‐Jun , Cao Cheng‐Fei , Qu Zhang‐Hao , Song Jiang , Li Shi‐Neng , Gao Jie‐Feng , Song Pingan , Zhang Guo‐Dong , Shi Yong‐Qian , Tang Long‐Cheng
Published: February 2024

MXene‐based thermal camouflage materials have gained increasing attention due to their low emissivity, however, the poor anti‐oxidation restricts their potential applications under complex environments. Various modification methods and strategies, e.g., the addition of antioxidant molecules and fillers have been developed to overcome this, but the realization of long‐term, reliable thermal camouflage using MXene network (coating) with excellent comprehensive performance remains a great challenge. Here, a MXene‐based hybrid network comodified with hyaluronic acid (HA) and hyperbranched polysiloxane (HSi) molecules is designed and fabricated. Notably, the presence of appreciated HA molecules restricts the oxidation of MXene sheets without altering infrared stealth performance, superior to other water‐soluble polymers; while the HSi molecules can act as efficient cross‐linking agents to generate strong interactions between MXene sheets and HA molecules. The optimized MXene/HA/HSi composites exhibit excellent mechanical flexibility (folded into crane structure), good water/solvent resistance, and long‐term stable thermal camouflage capability (with low infrared emissivity of ≈0.29). The long‐term thermal camouflage reliability (≈8 months) under various outdoor weathers and the scalable coating capability of the MXene‐coated textile enable them to disguise the IR signal of various targets in complex environments, indicating the great promise of achieved material for thermal camouflage, IR stealth, and counter surveillance.
Hydrogen Bond‐Mediated Self‐Shielded Moisture‐Responsive Structural Color for Time‐Temperature Indicating
Authors: Kou Donghui , Gao Lei , Lin Ruicheng , Zhang Shufen , Ma Wei
Published: February 2024

Effective monitoring of the time‐temperature history of biological reagents, chemical drugs, and perishable foods during cold chain storage is crucial for ensuring their quality and efficacy. Time‐temperature indicators (TTIs) are developed to assess the cumulative impact of time and temperature on product quality. However, current indicators face challenges related to complex wrapping procedures, narrow tracking ranges, susceptibility to photobleaching, and pre‐use instability, hampering widespread use. Herein, the first moisture‐responsive 1D photonic crystal (1DPC) TTIs featuring robust structural colors, customizable time‐temperature ranges, and reliable renewability are demonstrated. The indicators exhibit distinct color‐changing responsiveness toward water vapor, which remains observable after prolonged storage at low temperatures. Significantly, the moisture responsiveness gradually diminishes at elevated temperatures over time due to ambient water‐induced hydrogen bond formation, effectively shielding the indicator from external stimuli. This property enables the naked‐eye inspection of product efficacy during cold chain storage. Additionally, the endowed flexibility of the TTI facilitates its easy attachment to targets, functioning as a convenient indicator label. Remarkably, the indicator can be stably stored for an extended period at room temperature before use, thereby showcasing substantial market potential.
Synergistic Integration of Nanogenerators and Solar Cells: Advanced Hybrid Structures and Applications
Authors: Hajra Sugato , Ali Amanat , Panda Swati , Song Heewoon , Rajaitha P. M. , Dubal Deepak , Borras Ana , In‐Na Pichaya , Vittayakorn Naratip , Vivekananthan Venkateswaran , Kim Hoe Joon , Divya Sivasubramani , Oh Tae Hwan
Published: February 2024

The rapid growth of global energy consumption and the increasing demand for sustainable and renewable energy sources have urged vast research into harnessing energy from various sources. Among them, the most promising approaches are nanogenerators (NGs) and solar cells (SCs), which independently offer innovative solutions for energy harvesting. This review paper presents a comprehensive analysis of the integration of NGs and SCs, exploring advanced hybrid structures and their diverse applications. First, an overview of the principles and working mechanisms of NGs and SCs is provided for seamless hybrid integrations. Then, various design strategies are discussed, such as piezoelectric and triboelectric NGs with different types of SCs. Finally, a wide range of applications are explored that benefit from the synergistic integration of NGs and SCs, including self‐powered electronics, wearable devices, environmental monitoring, and wireless sensor networks. The potential for these hybrid systems is highlighted to address real‐world energy needs and contribute to developing sustainable and self‐sufficient technologies. In conclusion, this review provides valuable insights into the state‐of‐the‐art developments in NGs and SCs integration, shedding light on advanced hybrid structures and their diverse applications.
Capturing mesoscale structures in computational fluid dynamics simulations of gas‐solid flows
Authors: Kumar Balivada Kusum , Ganesh Swathi , Goyal Himanshu
Published: February 2024

Multiphase reactors' performance depends on the mesoscale structures formed due to multiphase hydrodynamics. Examples of mesoscale structures include gas bubbles in a fluidized bed and particle clusters in a riser. Experimental investigation of these mesoscale structures is challenging and expensive. To this end, computational fluid dynamics (CFD) simulations are extensively employed; however, post‐processing CFD data to capture mesoscale structures is challenging. This article develops a density‐based spatial clustering of applications with noise (DBSCAN)‐based methodology to capture and characterize mesoscale structures from multiphase CFD simulation data. DBSCAN is an unsupervised machine‐learning algorithm, which requires the value of two hyperparameters. A simple technique to calculate these hyperparameters is provided and the performance of DBSCAN is assessed on CFD‐DEM simulations of bubbling fluidized beds and particle clustering. We demonstrate the computational complexity of DBSCAN to be , lower than the existing techniques, by testing its scalability on highly resolved grids (up to 100 million grid points).