Search

Suspension bridge’s main cable under live load undergoes deformation depending on its gravity stiffness, i.e., work done against gravity under the initial dead load. In three-tower suspension bridges (3TSB), the middle tower's effect on the main cable's gravity stiffness is crucial but hard to assess. In this paper, the 3TSB model was simplified to the 2TSB with elastic constraints. The main cable shape was then calculated via the ratio between the simply supported beam's bending moment and the horizontal force component. The 2TSB model results were used to derive the 3TSB main cable's deflection using the middle tower's stiffness under vertical load. The analytical formula for gravity stiffness of 3TSB was derived by matching the latter with the simply supported beam's deflection formula. For a case-study 3TSB with main spans of 248 m + 1060 m + 1360 m + 380 m, analytical predictions were verified by FEM numerical results obtained via ANSYS. Linear relationships between live load and increments of the main cable's deflection and horizontal force component were derived. Besides, the main cable's deflection under live load can be reduced by increasing its sag-to-span ratio and cross-sectional area.

Whole-brain mesoscale mapping in primates has been hindered by large brain sizes and the relatively low throughput of available microscopy methods. Here, we present an approach that combines primate-optimized tissue sectioning and clearing with ultrahigh-speed fluorescence microscopy implementing improved volumetric imaging with synchronized on-the-fly-scan and readout technique, and is capable of completing whole-brain imaging of a rhesus monkey at 1 × 1 × 2.5 µm3 voxel resolution within 100 h. We also developed a highly efficient method for long-range tracing of sparse axonal fibers in datasets numbering hundreds of terabytes. This pipeline, which we call serial sectioning and clearing, three-dimensional microscopy with semiautomated reconstruction and tracing (SMART), enables effective connectome-scale mapping of large primate brains. With SMART, we were able to construct a cortical projection map of the mediodorsal nucleus of the thalamus and identify distinct turning and routing patterns of individual axons in the cortical folds while approaching their arborization destinations. A whole monkey brain is imaged at high resolution in 100 hours.

The speed of high-resolution optical imaging has been a rate-limiting factor for meso-scale mapping of brain structures and functional circuits, which is of fundamental importance for neuroscience research. Here, we describe a new microscopy method of Volumetric Imaging with Synchronized on-the-fly-scan and Readout (VISoR) for high-throughput, high-quality brain mapping. Combining synchronized scanning beam illumination and oblique imaging over cleared tissue sections in smooth motion, the VISoR system effectively eliminates motion blur to obtain undistorted images. By continuously imaging moving samples without stopping, the system achieves high-speed 3D image acquisition of an entire mouse brain within 1.5 hours, at a resolution capable of visualizing synaptic spines. A pipeline is developed for sample preparation, imaging, 3D image reconstruction and quantification. Our approach is compatible with immunofluorescence methods, enabling flexible cell-type specific brain mapping and is readily scalable for large biological samples such as primate brains. Using this system, we examined behaviorally relevant whole-brain neuronal activation in 16 c-Fos-shEGFP mice under resting or forced swimming conditions. Our results indicate the involvement of multiple subcortical areas in stress response. Intriguingly, neuronal activation in these areas exhibits striking individual variability among different animals, suggesting the necessity of sufficient cohort size for such studies.

Triple-tower suspension bridges with two asymmetrical main spans can adapt to complicated terrain conditions. If the top and bottom main cables with different sags are used on the two main...

Whole-brain mesoscale mapping of primates has been hindered by large brain size and the relatively low throughput of available microscopy methods. Here, we present an integrative approach that combines primate-optimized tissue sectioning and clearing with ultrahigh-speed, large-scale, volumetric fluorescence microscopy, capable of completing whole-brain imaging of a rhesus monkey at 1 µm × 1 µm × 2.5 µm voxel resolution within 100 hours. A progressive strategy is developed for high-efficiency, long-range tracing of individual axonal fibers through the dataset of hundreds of terabytes, establishing a “Serial sectioning and clearing, 3-dimensional Microscopy, with semi-Automated Reconstruction and Tracing” (SMART) pipeline. This system supports effective connectome-scale mapping of large primates that reveals distinct features of thalamocortical projections of the rhesus monkey brain at the level of individual axonal fibers.

Whole-brain mesoscale mapping in primates has been hindered by large brain sizes and the relatively low throughput of available microscopy methods. Here, we present an approach that combines primate-optimized tissue sectioning and clearing with ultrahigh-speed fluorescence microscopy implementing improved volumetric imaging with synchronized on-the-fly-scan and readout technique, and is capable of completing whole-brain imaging of a rhesus monkey at 1 × 1 × 2.5 µm

Three-pylon suspension bridges with unequal main-span lengths are terrain-adaptive, and this feature makes them suitable for broad applications. However, the design and construction control...

The use of a computation-guided method and the discovered structure–property relationship would establish a rational strategy to aid the development of ethanol oxidation reaction (EOR) catalysts for possible commercialization of direct ethanol fuel cells. Here, we investigate the promotion roles of additive metals in ternary Pt–Sn–Ag catalysts toward EOR via a combination of density functional theory calculation and experimental evidence. By calculating the EOR energetics, the promotion roles of Sn and Ag were revealed from the viewpoints of electronic and structural effects, respectively: (1) The addition of Sn and Ag on Pt essentially reduce the reaction energy and activation barrier of the second two-electron transfer process of EOR, facilitating the oxidation of acetaldehyde to acetic acid; (2) a homogeneous Pt–Sn–Ag surface configuration strengthens the adsorption energy of ethanol, thus improving the activity for ethanol oxidizing to acetaldehyde. Experimentally, various Pt–Sn–Ag nanorod catalysts ...

Self-injurious behavior (SIB) is commonly observed in patients with neuropsychiatric disorders, as well as in nonclinical populations with stress-related mental-health problems. However, the exact circuitry mechanisms underlying SIB have remained poorly understood. Here, with bilateral injection of muscimol into the entopeduncular nucleus (EP), we established a rat model of SIB. Following the muscimol injection, the male rats exhibited in a dose-dependent manner stereotypic self-biting behavior that lasted for hours and often resulted in wounds of various severities. The SIB was associated with an elevated level of serum corticosterone and could be exacerbated by enhancing the corticosterone signaling and, conversely, alleviated by inhibiting the corticosterone signaling. Activity mapping using c-fos immunostaining, combined with connectivity mapping using herpes simplex virus-based anterograde tracing from the EP and pseudorabies virus-based retrograde tracing from the masseter muscle, revealed the potential involvement of many brain areas in SIB. In particular, the lateral habenula (LHb) and the ventral tegmental area (VTA), the two connected brain areas involved in stress response and reward processing, showed a significant increase in neuronal activation during SIB. Furthermore, suppressing the LHb activity or modulating the GABAergic transmission in the VTA could significantly reduce the occurrence of SIB. These results demonstrate the importance of stress hormone signaling and the LHb–VTA circuit in modulating SIB resulting from EP malfunction, and suggest potential targets for therapeutic intervention of SIB and related disorders. SIGNIFICANCE STATEMENT Self-injurious behavior (SIB) occurs in ∼4% of the general population, with substantially higher occurrence among adolescents and patients of neuropsychiatric disorders. Stress has been linked to the occurrence of SIB, yet the underlying mechanisms have remained unclear. Using a rat model of SIB induced by disruption of activity in the entopeduncular nucleus (EP), we found that the behavior is regulated by stress and linked to corticosterone signaling. Viral tracing and c-fos immunostaining revealed the involvement of various subcortical areas, especially the EP–lateral habenula (LHb)–ventral tegmental area (VTA) circuit, in SIB. Furthermore, regulating activity in the LHb or the VTA alleviates SIB. These results may have implications in the development of new strategies for treating SIB.

The development of Pt-based bimetallic catalysts for ethanol oxidation reaction (EOR) is an important subject to enhance the performance of the promising and clean direct ethanol fuel cells (DEFCs). In this study, we thoroughly investigated EOR activity on Pt and its bimetallic catalysts PtM (M = Au, Ag and Sn) with different degrees of oxophilicity. The computational results found that EOR on Pt-based catalysts prefers the sequence of CH3CH2OH* → CH3CH2O* → CH3CHO* to form the main product of acetaldehyde and rate-determining step is controlled in the initial O H bond cleavage. The foreign elements M can reduce the barrier to some extents. Additionally, their surface oxygen containing species (OCS) can further lower the barrier to better enhance EOR activity. Among those PtM, PtSn has the highest oxophilicity and the most abundant surface OCS, which can most effectively lower the barrier. Thus, the computational study predicted that PtSn shows the best EOR activity through bifunctional mechanism. Experimentally, PtM nanorods with varied surface OCS have been synthesized, characterized and applied for electrochemical tests. The enhanced EOR activity was observed on the PtM with significant amount of surface OCS. The computational and experimental efforts concluded that the oxophilicity plays an important role for the enhanced EOR activity, attributable to the highly active surface OCS.

Death domain (DD)-fold assemblies play a crucial role in regulating the signaling to cell survival or death. Here we report the crystal structure of the caspase recruitment domain (CARD)-CARD disk of the human apoptosome. The structure surprisingly reveals that three 1:1 Apaf-1:procaspase-9 CARD protomers form a novel helical DD-fold assembly on the heptameric wheel-like platform of the apoptosome. The small-angle X-ray scattering and multi-angle light scattering data also support that three protomers could form an oligomeric complex similar to the crystal structure. Interestingly, the quasi-equivalent environment of CARDs could generate different quaternary CARD assemblies. We also found that the type II interaction is conserved in all DD-fold complexes, whereas the type I interaction is found only in the helical DD-fold assemblies. This study provides crucial insights into the caspase activation mechanism, which is tightly controlled by a sophisticated and highly evolved CARD assembly on the apoptosome, and also enables better understanding of the intricate DD-fold assembly.

Neuron segmentation is an important task for automatic analyses of brain images that are of huge volume. Previous methods for neuron segmentation rely on handcrafted image features, and have difficulty in coping with high-resolution, low signal-to-noise-ratio brain images. Convolutional neural network (CNN) has achieved remarkable success in natural image segmentation, but CNN requires accurately labeled data for training that are difficult to achieve on brain images of huge volume. In this paper, we present a weakly supervised learning strategy to deal with the inaccurate training data problem, and thus adopt 3D CNN to perform automatic soma segmentation from brain images. We test our method on our own collected mouse brain images that are of single-neuron resolution, and results show that 3D CNN-based method outperforms the traditional methods by a significant margin.

We describe a new light-sheet microscopy method for fast, large-scale volumetric imaging. Combining synchronized scanning illumination and oblique imaging over cleared, thick tissue sections in smooth motion, our approach achieves high-speed 3D image acquisition of an entire mouse brain within 2 hours, at a resolution capable of resolving synaptic spines. It is compatible with immunofluorescence labeling, enabling flexible cell-type specific brain mapping, and is readily scalable for large biological samples such as primate brain.

This paper presents a novel tone mapping method for the display of high dynamic range (HDR) 3D brain images at single-neuron resolution, where the fluorescent labeled neurons exhibit extremely high local contrast. Existing tone mapping methods fit for natural images cannot well preserve the details of neurons in the 3D brain image, and require huge memory when the image resolution is ultra high. Therefore, we propose a block-wise, progressive tone mapping strategy for efficient and high quality display of such image, which further offers two different modes for optimum global or local visual experience. Experimental results demonstrate that the proposed approach significantly improves the visualization quality of high contrast neurons in HDR brain images compared with existing methods.

Three-tower suspension bridges with unequal-length main spans more easily adapt to different terrain features and therefore, have broader application prospects. However, due to the unique “central tower effect” of the three-tower suspension bridge, it is required that the lateral stiffness of the central tower in the longitudinal direction of the bridge girder should be neither too large nor too small. To calculate the reasonable range for the central tower stiffness in the three-tower suspension bridge with unequal-length main spans, this study proposes an analytical algorithm based on the segmental catenary theory. Firstly, hanger tensile forces under the joint action of dead and live loads are calculated. Next, the governing equations for the main cable shape of each span are constructed for the following conditions: closure of elevation difference, closure of span length, moment balance of splay saddle, and conservation of unstrained length of the main cable. The solutions of the derived set of simultaneous equations are obtained for (i) deflection-to-span ratio limit of the stiffening girder and (ii) anti-slip control between the main cable and saddle conditions, which yield the lower and upper limits of reasonable stiffness of the central tower, respectively. This study discusses a three-tower suspension bridge spanned as 248 m + 1060 m + 1360 m + 380 m. The calculation is performed for the two cases of the live load application: (i) to the longer main span and (ii) to the shorter main span. The results obtained proved the feasibility and effectiveness of the proposed algorithm. The following findings are reported: The upper and lower limits of reasonable central tower stiffness are derived from the above two cases, respectively. Therefore, it is not sufficient to consider only the former case when calculating the central tower stiffness of the three-tower suspension bridge with equal-length main spans. The dead-to-live load ratio and friction coefficient between the main cable and saddle also strongly influence the central tower stiffness: their increase can expand the reasonable range of the latter but if they are too small, no such optimization can be provided.

One emerging principle is that neuromodulators, such as neuropeptides, regulate multiple behaviors, particularly motivated behaviors, e.g., feeding and locomotion. However, how neuromodulators act on multiple neural networks to exert their actions remains poorly understood. These actions depend on the chemical form of the peptide, e.g., an alternation of L- to D- form of an amino acid can endow the peptide with bioactivity, as is the case for the Aplysia peptide GdFFD (where dF indicates D-phenylalanine). GdFFD has been shown to act as an extrinsic neuromodulator in the feeding network, while the all L-amino acid form, GFFD, was not bioactive. Given that both GdFFD/GFFD are also present in pedal neurons that mediate locomotion, we sought to determine whether they impact locomotion. We first examined effects of both peptides on isolated ganglia, and monitored fictive programs using the parapedal commissural nerve (PPCN). Indeed, GdFFD was bioactive and GFFD was not. GdFFD increased the frequency with which neural activity was observed in the PPCN. In part, there was an increase in bursting spiking activity that resembled fictive locomotion. Additionally, there was significant activity between bursts. To determine how the peptide-induced activity in the isolated CNS is translated into behavior, we recorded animal movements, and developed a computer program to automatically track the animal and calculate the path of movement and velocity of locomotion. We found that GdFFD significantly reduced locomotion and induced a foot curl. These data suggest that the increase in PPCN activity observed in the isolated CNS during GdFFD application corresponds to a reduction, rather than an increase, in locomotion. In contrast, GFFD had no effect. Thus, our study suggests that GdFFD may act as an intrinsic neuromodulator in the Aplysia locomotor network. More generally, our study indicates that physiological and behavioral analyses should be combined to evaluate peptide actions.

CARD subfamily is the second largest subfamily in the DD superfamily that plays important roles in regulating various signaling pathways, including but not limited to NF-kB activation signaling, apoptosis signaling and inflammatory signaling. The CARD subfamily contains 33 human CARD-containing proteins, regulating the assembly of many signaling complexes, including apoptosome, inflammsome, nodosome, the CBM complex, PIDDosome, the TRAF2 complex, and the MAVS signalosome, by homotypic CARD-CARD interactions. The mechanism of how CARDs find the right binding partner to form a specific complex remains unclear. This review uses different classification schemes to update the classification of CARD-containing proteins. Combining the classification based on domain structures, functions, associated signaling complexes, and roles would help better understand the structural and function diversity of CARD-containing proteins. This review also summarizes recent structural studies on CARDs. Especially, the CARD-containing complexes can be divided into the homodimeric, heterodimeric, oligomeric, filamentous CARD complexes and the CARD-ubiquitin complex. This review will give an overview of the versatile roles of CARDs in regulating signaling transduction, as well as the therapeutic drugs targeting CARD-containing proteins.

Apoptosis is an important process to maintain cellular homeostasis. Deregulated apoptosis has linked to a number of diseases, such as inflammatory diseases, neurodegenerative disorder, and cancers. A major signaling complex in the death receptor signaling pathway leading to apoptosis is death-induced signaling complex (DISC), which is regulated mainly by death effector domain (DED)-containing proteins. There are seven DED-containing proteins in human, including FADD, c-FLIP, caspase-8, caspase-10, DEDD, DEDD2, and PEA-15. The main players in DISC formation employ tandem DEDs for regulating signaling complex formation. The regulatory mechanism of signaling complex formation is important and yet remains unclear. Interestingly, three caspase recruitment domain (CARD)-containing members, which belong to the same DD superfamily as DED-containing proteins, also contains similar tandem CARDs. Recent structural studies have shown that tandem CARDs are essential for the formation of a helical signaling complex. This review summarizes recent structural studies on DED-containing proteins and especially discusses the studies on tandem DEDs and tandem CARDs, which suggest new mechanisms of signaling complex assembly.