Research on the Structural Rigidity Characteristics of a Reconfigurable TBM Thrust Mechanism

AbstractTo improve the adaptability of TBMs in diverse geological environments, this paper proposes a reconfigurable Type-V thrust mechanism (V-TM) with rearrangeable working states, in which structural stiffness can be automatically altered during operation. Therefore, millions of configurations can be obtained, and thousands of instances of working status per configuration can be set respectively. Nonetheless, the complexity of configurations and diversity of working states contributes to further complications for the structural stiffness algorithm. This results in challenges such as difficulty calculating the payload compliance index and the environment adaptability index. To solve this problem, we use the configuration matrix to describe the relationship between propelling jacks under reconfiguration and adopt pattern vectors to describe the working state of each hydraulic cylinder. Then, both the dynamic compatible equation between propeller forces of the hydraulic cylinders and driving forces, and the kinematic harmonizing equation between the hydraulic cylinder displacements and their deformations are established. Next, we derive the stiffness analytical equation using Hooke's law and the Jacobian Matrix. The proposed approach provides an effective algorithm to support structural rigidity analysis, and lays a solid theoretical foundation for calculating the performance indexes of the V-TM. We then analyze the rigidity characteristics of typical configurations under different working states, and obtain the main factors affecting structural stiffness of the V-TM. The results show the deviation degree of structural parameters in hydraulic cylinders within the same group, and the working status of propelling jacks. Finally, our constructive conclusions contribute valuable information for matching and optimization by drawing on the factors that affect the structural rigidity of the V-TM

Melanocortin 1 receptor targeted imaging of melanoma with gold nanocages and positron emission tomography

Purpose: Melanoma is a lethal skin cancer with unmet clinical needs for targeted imaging and therapy. Nanoscale materials conjugated with targeting components have shown great potential to improve tumor delivery efficiency while minimizing undesirable side effects in vivo. Herein, we proposed to develop targeted nanoparticles for melanoma theranostics. Method: In this work, gold nanocages (AuNCs) were conjugated with α-melanocyte-stimulating hormone (α-MSH) peptide and radiolabeled with 64Cu for melanocortin 1 receptor-(MC1R) targeted positron emission tomography (PET) in a mouse B16/F10 melanoma model. Results: Their controlled synthesis and surface chemistry enabled well-defined structure and radiolabeling efficiency. In vivo pharmacokinetic evaluation demonstrated comparable organ distribution between the targeted and nontargeted AuNCs. However, micro-PET/computed tomography (CT) imaging demonstrated specific and improved tumor accumulation via MC1R-mediated delivery. By increasing the coverage density of α-MSH peptide on AuNCs, the tumor delivery efficiency was improved. Conclusion: The controlled synthesis, sensitive PET imaging, and optimal tumor targeting suggested the potential of targeted AuNCs for melanoma theranostics. </jats:sec

Radially Aligned, Electrospun Nanofibers as Dural Substitutes for Wound Closure and Tissue Regeneration Applications

This paper reports the fabrication of scaffolds consisting of radially aligned poly(ε-caprolactone) nanofibers by utilizing a collector composed of a central point electrode and a peripheral ring electrode. This novel class of scaffolds was able to present nanoscale topographic cues to cultured cells, directing and enhancing their migration from the periphery to the center. We also established that such scaffolds could induce faster cellular migration and population than nonwoven mats consisting of random nanofibers. Dural fibroblast cells cultured on these two types of scaffolds were found to express type I collagen, the main extracellular matrix component in dural mater. The type I collagen exhibited a high degree of organization on the scaffolds of radially aligned fibers and a haphazard distribution on the scaffolds of random fibers. Taken together, the scaffolds based on radially aligned, electrospun nanofibers show great potential as artificial dural substitutes and may be particularly useful as biomedical patches or grafts to induce wound closure and/or tissue regeneration

In vivo evaluation of adipose-derived stromal cells delivered with a nanofiber scaffold for tendon-to-bone repair

Rotator cuff tears are common and cause a great deal of lost productivity, pain, and disability. Tears are typically repaired by suturing the tendon back to its bony attachment. Unfortunately, the structural (e.g., aligned collagen) and compositional (e.g., a gradient in mineral) elements that produce a robust attachment in the healthy tissue are not regenerated during healing, and the repair is prone to failure. Two features of the failed healing response are deposition of poorly aligned scar tissue and loss of bone at the repair site. Therefore, the objective of the current study was to improve tendon-to-bone healing by promoting aligned collagen deposition and increased bone formation using a biomimetic scaffold seeded with pluripotent cells. An aligned nanofibrous poly(lactic-co-glycolic acid) scaffold with a gradient in mineral content was seeded with adipose-derived stromal cells (ASCs) and implanted at the repair site of a rat rotator cuff model. In one group, cells were transduced with the osteogenic factor bone morphogenetic protein 2 (BMP2). The healing response was examined in four groups (suture only, acellular scaffold, cellular scaffold, and cellular BMP2 scaffold) using histologic, bone morphology, and biomechanical outcomes at 14, 28, and 56 days. Histologically, the healing interface was dominated by a fibrovascular scar response in all groups. The acellular scaffold group showed a delayed healing response compared to the other groups. When examining bone morphology parameters, bone loss was evident in the cellular BMP2 group compared to other groups at 28 days. When examining repair-site mechanical properties, strength and modulus were decreased in the cellular BMP2 groups compared to other groups at 28 and 56 days. These results indicated that tendon-to-bone healing in this animal model was dominated by scar formation, preventing any positive effects of the implanted biomimetic scaffold. Furthermore, cells transduced with the osteogenic factor BMP2 led to impaired healing, suggesting that this growth factor should not be used in the tendon-to-bone repair setting

Denoising enabled channel estimation for underwater acoustic communications: A sparsity-aware model-driven learning approach

It has always been difficult to achieve accurate information of the channel for underwater acoustic communications because of the severe underwater propagation conditions, including frequency-selective property, high relative mobility, long propagation latency, and intensive ambient noise, etc. To this end, a deep unfolding neural network based approach is proposed, in which multiple layers of the network mimic the iterations of the classical iterative sparse approximation algorithm to extract the inherent sparse features of the channel by exploiting deep learning, and a scheme based on the Sparsity-Aware DNN (SA-DNN) for UAC estimation is proposed to improve the estimation accuracy. Moreover, we propose a Denoising Sparsity-Aware DNN (DeSA-DNN) based enhanced method that integrates a denoising CNN module in the sparsity-aware deep network, so that the degradation brought by intensive ambient noise could be eliminated and the estimation accuracy can be further improved. Simulation results demonstrate that the performance of the proposed schemes is superior to the state-of-the-art compressed sensing based and iterative sparse recovery schems in the aspects of channel recovery precision, pilot overhead, and robustness, particularly under unideal circumstances of intensive ambient noise or inadequate measurement pilots

Radioactive ^(198)Au-Doped Nanostructures with Different Shapes for In Vivo Analyses of Their Biodistribution, Tumor Uptake, and Intratumoral Distribution

With Au nanocages as an example, we recently demonstrated that radioactive ^(198)Au could be incorporated into the crystal lattice of Au nanostructures for simple and reliable quantification of their in vivo biodistribution by measuring the γ radiation from ^(198)Au decay and for optical imaging by detecting the Cerenkov radiation. Here we extend the capability of this strategy to synthesize radioactive ^(198)Au nanostructures with a similar size but different shapes and then compare their biodistribution, tumor uptake, and intratumoral distribution using a murine EMT6 breast cancer model. Specifically, we investigated Au nanospheres, nanodisks, nanorods, and cubic nanocages. After PEGylation, an aqueous suspension of the radioactive Au nanostructures was injected into a tumor-bearing mouse intravenously, and their biodistribution was measured from the γ radiation while their tumor uptake was directly imaged using the Cerenkov radiation. Significantly higher tumor uptake was observed for the Au nanospheres and nanodisks relative to the Au nanorods and nanocages at 24 h postinjection. Furthermore, autoradiographic imaging was performed on thin slices of the tumor after excision to resolve the intratumoral distributions of the nanostructures. While both the Au nanospheres and nanodisks were only observed on the surfaces of the tumors, the Au nanorods and nanocages were distributed throughout the tumors

Integrated microfluidic tmRNA purification and real-time NASBA device for molecular diagnostics.

We demonstrate the first integrated microfluidic tmRNA purification and nucleic acid sequence-based amplification (NASBA) device incorporating real-time detection. The real-time amplification and detection step produces pathogen-specific response in < 3 min from the chip-purified RNA from 100 lysed bacteria. On-chip RNA purification uses a new silica bead immobilization method. On-chip amplification uses custom-designed high-selectivity primers and real-time detection uses molecular beacon fluorescent probe technology; both are integrated on-chip with NASBA. Present in all bacteria, tmRNA (10Sa RNA) includes organism-specific identification sequences, exhibits unusually high stability relative to mRNA, and has high copy number per organism; the latter two factors improve the limit of detection, accelerate time-to-positive response, and suit this approach ideally to the detection of small numbers of bacteria. Device efficacy was demonstrated by integrated on-chip purification, amplification, and real-time detection of 100 E. coli bacteria in 100 microL of crude lysate in under 30 min for the entire process

A Facile and General Method for the Encapsulation of Different Types of Imaging Contrast Agents Within Micrometer-Sized Polymer Beads

Polystyrene (PS) hollow beads with holes on the surfaces are employed as containers for quick loading and encapsulation of a variety of contrast enhancement agents: saline solutions for thermoacoustic tomography, iodinated organic compounds for micro-computed tomography, and perfluorooctane for magnetic resonance. Because of the hole on the surface of the PS hollow bead, the contrast agent to be encapsulated could quickly enter the hollow interior via direct flow rather than slow diffusion through the wall. After loading, the hole on the surface is conveniently sealed by annealing the sample at a temperature (e.g., 95 °C) slightly above the glass-transition temperature of PS. In vitro methods are also used to investigate the effectiveness of encapsulation by quantifying the contrast enhancement enabled by the contrast agents

Enhanced hemangioblast generation and improved vascular repair and regeneration from embryonic stem cells by defined transcription factors

SummaryThe fetal liver kinase 1 (FLK-1)+ hemangioblast can generate hematopoietic, endothelial, and smooth muscle cells (SMCs). ER71/ETV2, GATA2, and SCL form a core transcriptional network in hemangioblast development. Transient coexpression of these three factors during mesoderm formation stage in mouse embryonic stem cells (ESCs) robustly enhanced hemangioblast generation by activating bone morphogenetic protein (BMP) and FLK-1 signaling while inhibiting phosphatidylinositol 3-kinase, WNT signaling, and cardiac output. Moreover, etsrp, gata2, and scl inhibition converted hematopoietic field of the zebrafish anterior lateral plate mesoderm to cardiac. FLK-1+ hemangioblasts generated by transient coexpression of the three factors (ER71-GATA2-SCL [EGS]-induced FLK-1+) effectively produced hematopoietic, endothelial, and SMCs in culture and in vivo. Importantly, EGS-induced FLK-1+ hemangioblasts, when codelivered with mesenchymal stem cells as spheroids, were protected from apoptosis and generated functional endothelial cells and SMCs in ischemic mouse hindlimbs, resulting in improved blood perfusion and limb salvage. ESC-derived, EGS-induced FLK-1+ hemangioblasts could provide an attractive cell source for future hematopoietic and vascular repair and regeneration

Comparison Study of Gold Nanohexapods, Nanorods, and Nanocages for Photothermal Cancer Treatment

Gold nanohexapods represent a novel class of optically tunable nanostructures consisting of an octahedral core and six arms grown on its vertices. By controlling the length of the arms, their localized surface plasmon resonance peaks could be tuned from the visible to the near-infrared region for deep penetration of light into soft tissues. Herein we compare the in vitro and in vivo capabilities of Au nanohexapods as photothermal transducers for theranostic applications by benchmarking against those of Au nanorods and nanocages. While all these Au nanostructures could absorb and convert near-infrared light into heat, Au nanohexapods exhibited the highest cellular uptake and the lowest cytotoxicity in vitro for both the as-prepared and PEGylated nanostructures. In vivo pharmacokinetic studies showed that the PEGylated Au nanohexapods had significant blood circulation and tumor accumulation in a mouse breast cancer model. Following photothermal treatment, substantial heat was produced in situ and the tumor metabolism was greatly reduced for all these Au nanostructures, as determined with ^(18)F-flourodeoxyglucose positron emission tomography/computed tomography (^(18)F-FDG PET/CT). Combined together, we can conclude that Au nanohexapods are promising candidates for cancer theranostics in terms of both photothermal destruction and contrast-enhanced diagnosis