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Primary cilia in hard tissue development and diseases

《医学前沿（英文）》 2021年第15卷第5期页码 657-678 doi: 10.1007/s11684-021-0829-6

摘要： Bone and teeth are hard tissues. Hard tissue diseases have a serious effect on human survival and quality of life. Primary cilia are protrusions on the surfaces of cells. As antennas, they are distributed on the membrane surfaces of almost all mammalian cell types and participate in the development of organs and the maintenance of homeostasis. Mutations in cilium-related genes result in a variety of developmental and even lethal diseases. Patients with multiple ciliary gene mutations present overt changes in the skeletal system, suggesting that primary cilia are involved in hard tissue development and reconstruction. Furthermore, primary cilia act as sensors of external stimuli and regulate bone homeostasis. Specifically, substances are trafficked through primary cilia by intraflagellar transport, which affects key signaling pathways during hard tissue development. In this review, we summarize the roles of primary cilia in long bone development and remodeling from two perspectives: primary cilia signaling and sensory mechanisms. In addition, the cilium-related diseases of hard tissue and the manifestations of mutant cilia in the skeleton and teeth are described. We believe that all the findings will help with the intervention and treatment of related hard tissue genetic diseases.

关键词： primary cilia bone mechanical sensing hard tissue cilium-related bone disease tooth

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Analysis of load and adaptability of disc cutters during shield tunneling in soft–hard varied strata

《结构与土木工程前沿（英文）》 2023年第17卷第4期页码 533-545 doi: 10.1007/s11709-023-0946-1

摘要： The disc cutters of shield machines exhibit unsatisfactory adaptability and performance during the soft–hard varied strata tunneling process. To analyze the rotation state, cutting performance, and adaptability of disc cutters during shield tunneling in soft–hard varied strata, the Holmquist Johnson Cook and Federal Highway Administration constitutive models are introduced to numerically simulate the failure process of materials on the excavation face and to calculate the load of disc cutters. Additionally, the parameters of the models are modified based on laboratory disc cutter excavation test results. The results of numerical calculation can reflect the load level and the behavior of the disc cutters during operation. The tangential loads of the disc cutters during the cutting of four typical soft-strata excavation face models are numerically calculated, thus providing reference values for the starting torque of the disc cutters. A greater penetration is suggested for soft-strata tunneling to allow the disc cutters to rotate smoothly and continuously as well as to guarantee a better cutting effect. The disc cutters in the center of the cutterhead should be specified with a lower starting torque to prevent uneven wear, rotation stagnation, cutterhead clogging, and other adverse phenomena.

关键词： shield tunneling disc cutter load laboratory excavation test numerical calculation soft–hard varied strata

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Advances in molecular dynamics simulation of ultra-precision machining of hard and brittle materials

Xiaoguang GUO,Qiang LI,Tao LIU,Renke KANG,Zhuji JIN,Dongming GUO

《机械工程前沿（英文）》 2017年第12卷第1期页码 89-98 doi: 10.1007/s11465-017-0412-7

摘要：

Hard and brittle materials, such as silicon, SiC, and optical glasses, are widely used in aerospace, military, integrated circuit, and other fields because of their excellent physical and chemical properties. However, these materials display poor machinability because of their hard and brittle properties. Damages such as surface micro-crack and subsurface damage often occur during machining of hard and brittle materials. Ultra-precision machining is widely used in processing hard and brittle materials to obtain nanoscale machining quality. However, the theoretical mechanism underlying this method remains unclear. This paper provides a review of present research on the molecular dynamics simulation of ultra-precision machining of hard and brittle materials. The future trends in this field are also discussed.

关键词： MD simulation ultra-precision machining hard and brittle materials machining mechanism review

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浅埋深两硬条件下特厚煤层综放开采技术

张忠温,吴吉南

《中国工程科学》 2011年第13卷第11期页码 107-112

摘要：

针对平朔矿区4号煤层条件，采用理论分析方法研究了浅埋深两硬条件下4号煤层顶煤的冒放性及合理采煤方法。以提高顶煤冒放性为目标，采用数值模拟的方法进行了综放工作面参数及设备选型配套研究。实践表明，浅埋深两硬煤层条件下通过加大综放工作面长度与割煤高度，可以实现安全、高效、高回收率开采。

关键词：浅埋深两硬煤层顶煤冒放性大采高综放

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Crystalline mesoporous transition metal oxides: hard-templating synthesis and application in environmental

Zhen MA, Bei ZHOU, Yu REN

《环境科学与工程前沿（英文）》 2013年第7卷第3期页码 341-355 doi: 10.1007/s11783-012-0472-1

摘要： Mesoporous silicas such as MCM-41 and SBA-15 possess high surface areas, ordered nanopores, and excellent thermal stability, and have been often used as catalyst supports. Although mesoporous metal oxides have lower surface areas compared to mesoporous silicas, they generally have more diversified functionalities. Mesoporous metal oxides can be synthesized via a soft-templating or hard-templating approach, and these materials have recently found some applications in environmental catalysis, such as CO oxidation, N O decomposition, and elimination of organic pollutants. In this review, we summarize the synthesis of mesoporous transition metal oxides using mesoporous silicas as hard templates, highlight the application of these materials in environmental catalysis, and furnish some prospects for future development.

关键词： mesoporous materials silica metal oxide hard-templating environmental catalysis

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Field and laboratory experimental studies on hard-rock tunnel excavation based on disc cutter coupled

《结构与土木工程前沿（英文）》页码 1370-1386 doi: 10.1007/s11709-023-0947-0

摘要： The tunnel boring machine (TBM) is typically used in hard-rock tunnel excavation. Owing to the unsatisfactory adaptability of TBM to the surrounding rock, when crossing high-strength and high-wear strata, the TBM can easily cause defects, such as abnormal wear on cutters and overload damage to bearings, thus affecting the construction efficiency and cost. Therefore, high-pressure waterjet technology should be applied to assist in rock breaking for efficient TBM tunneling. In this study, the effects of water pressure, nozzle diameter, and nozzle speed on cutting are investigated via laboratory experiments of cutting hard rock using high-pressure waterjets. The penetration performance of the TBM under different water pressures is investigated via a field industrial penetration test. The results show that high-pressure waterjets are highly efficient for rock breaking and are suitable for industrial applications, as they can accommodate the advancing speed of the TBM and achieve high-efficiency rock breaking. However, during the operation of high-pressure waterjets, the ambient temperature and waterjet temperature in the tunnel increase significantly, which weakens the cooling effect of the cutterhead and decreases the construction efficiency of the TBM. Therefore, temperature control and cooling measures for high-pressure waterjets during their long-term operation must be identified. This study provides a useful reference for the design and construction of high-pressure water-jet-assisted cutterheads for breaking road headers.

关键词： tunnel boring machine hard-rock cutting free face disc cutter rock-cutting efficiency

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Atypical pituitary hormone–target tissue axis

《医学前沿（英文）》 2023年第17卷第1期页码 1-17 doi: 10.1007/s11684-022-0973-7

摘要： A long-held belief is that pituitary hormones bind to their cognate receptors in classical target glands to actuate their manifold functions. However, a number of studies have shown that multiple types of pituitary hormone receptors are widely expressed in non-classical target organs. Each pituitary gland-derived hormone exhibits a wide range of nonconventional biological effects in these non-classical target organs. Herein, the extra biological functions of pituitary hormones, thyroid-stimulating hormone, follicle-stimulating hormone, luteinizing hormone, adrenocorticotrophic hormone, and prolactin when they act on non-classical organs were summarized, defined by the novel concept of an “atypical pituitary hormone–target tissue axis.” This novel proposal explains the pathomechanisms of abnormal glucose and lipid metabolism, obesity, hypertension, fatty liver, and atherosclerosis while offering a more comprehensive and systematic insights into the coordinated regulation of environmental factors, genetic factors, and neuroendocrine hormones on human biological functions. The continued exploration of the physiology of the “atypical pituitary hormone–target tissue axis” could enable the identification of novel therapeutic targets for metabolic diseases.

关键词： thyroid-stimulating hormone follicle-stimulating hormone luteinizing hormone adrenocorticotrophic hormone prolactin

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Progress and perspectives of neural tissue engineering

null

《医学前沿（英文）》 2015年第9卷第4期页码 401-411 doi: 10.1007/s11684-015-0415-x

摘要：

Traumatic injuries to the nervous system lead to a common clinical problem with a quite high incidence and affect the patient’s quality of life. Based on a major challenge not yet addressed by current therapeutic interventions for these diseases, a novel promising field of neural tissue engineering has emerged, grown, and attracted increasing interest. This review provides a brief summary of the recent progress in the field, especially in combination with the research experience of the author’s group. Several important aspects related to tissue engineered nerves, including the theory on their construction, translation into the clinic, improvements in fabrication technologies, and the formation of a regenerative environment, are delineated and discussed. Furthermore, potential research directions for the future development of neural tissue engineering are suggested.

关键词： nerve injury tissue engineering nerve grafts

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The stem cell and tissue engineering research in Chinese ophthalmology

GE Jian, LIU Jingbo

《医学前沿（英文）》 2007年第1卷第1期页码 6-10 doi: 10.1007/s11684-007-0002-x

摘要： Much has been considerably developed recently in the ophthalmic research of stem cell (SC) and tissue engineering (TE). They have become closer to the clinical practice, standardized and observable. Leading edge research of SC and TE on the ocular surface reconstruction, neuroregeneration and protection, and natural animal model has become increasingly available. However, challenges remain on the way, especially on the aspects of function reconstruction and specific differentiation. This paper reviews the new developments in this area with an intention of identifying research priorities for the future.

关键词： available observable neuroregeneration protection function reconstruction

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Decellularized extracellular matrix mediates tissue construction and regeneration

《医学前沿（英文）》 2022年第16卷第1期页码 56-82 doi: 10.1007/s11684-021-0900-3

摘要： Contributing to organ formation and tissue regeneration, extracellular matrix (ECM) constituents provide tissue with three-dimensional (3D) structural integrity and cellular-function regulation. Containing the crucial traits of the cellular microenvironment, ECM substitutes mediate cell–matrix interactions to prompt stem-cell proliferation and differentiation for 3D organoid construction in vitro or tissue regeneration in vivo. However, these ECMs are often applied generically and have yet to be extensively developed for specific cell types in 3D cultures. Cultured cells also produce rich ECM, particularly stromal cells. Cellular ECM improves 3D culture development in vitro and tissue remodeling during wound healing after implantation into the host as well. Gaining better insight into ECM derived from either tissue or cells that regulate 3D tissue reconstruction or organ regeneration helps us to select, produce, and implant the most suitable ECM and thus promote 3D organoid culture and tissue remodeling for in vivo regeneration. Overall, the decellularization methodologies and tissue/cell-derived ECM as scaffolds or cellular-growth supplements used in cell propagation and differentiation for 3D tissue culture in vitro are discussed. Moreover, current preclinical applications by which ECM components modulate the wound-healing process are reviewed.

关键词： decellularized extracellular matrix 3D culture organoids tissue repair

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Improved CO

Mahboube Ghahramaninezhad, Fatemeh Mohajer, Mahdi Niknam Shahrak

《化学科学与工程前沿（英文）》 2020年第14卷第3期页码 425-435 doi: 10.1007/s11705-019-1873-5

摘要： Post-synthetic functionalization or modification has been regarded as a promising strategy to treat surfaces of adsorbents for their applications in targeted adsorption and separation processes. In this work, a novel microporous adsorbent for carbon capturing was developed via functionalization of zeolitic imidazolate framework-91 (ZIF-91) to generate a hard/hard (metal-oxygen) structure named as lithium-modified ZIF-91 (ZIF-91-OLi compound). To this purpose, the ZIF-91 compound as an intermediate product was achieved by reduction of ZIF-90 in the presence of NaBH as a good reducing agent. Afterwards, acidic hydrogen atoms in the hydroxyl groups of ZIF-91 were exchanged with lithium cations via reaction of -BuLi compound as an organo lithium agent through an appropriate procedure. In particular, the as-synthesized ZIF-91-OLi operated as an excellent electron-rich center for CO adsorption through trapping the positive carbon centers in the CO molecule. DFT calculations revealed that the presence of lithium over the surface of ZIF-91-OLi adsorbent plays an effective role in double enhancement of CO storage via creating a strong negative charge center at the oxygen atoms of the imidazolate linker as a result of the lithium/hydrogen exchange system. Finally, the selectivity of CO /N was investigated at different temperatures, revealing the ZIF-91-OLi as a selective adsorbent for industrial application.

关键词： hard/hard structure acidic hydrogen ZIF-91 carbon capture ZIF-91-OLi

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Non-closure of the peritoneum and subcutaneous tissue at radical hysterectomy: A randomized controlled

Zhou-Fang XIONG MD, Wei-Hong DONG MD, Ze-Hua WANG MD,

《医学前沿（英文）》 2010年第4卷第1期页码 112-116 doi: 10.1007/s11684-010-0016-7

摘要： We conducted a trial to assess the influence of closure or nonclosure of the peritoneum and subcutaneous tissue on the clinical outcomes of cervical cancer patients who underwent radical hysterectomy with lower abdominal cross incision. This randomized controlled trial was performed on 158 cervical cancer patients in our hospital between January 2002 and June 2004. Eighty-two patients were allocated to the “closure” group and 76 patients to the “nonclosure” group. Results showed that non-closure of the peritoneum and subcutaneous tissue could shorten operation time and febrile duration, reduce antibiotics requirement, increase the volume of drainage and decrease the incidence of liquefaction of subcutaneous fat (<0.05). There was no difference in blood loss, postoperative complications, bowel function restoration and post-operative stay between the two groups (>0.05). Our study revealed that closure of the peritoneum and subcutaneous tissue provides no immediate postoperative benefits while unnecessarily lengthening surgical time and anesthesia exposure. The practice of closure of the peritoneum and subcutaneous tissue at radical hysterectomy should be questioned.

关键词： cervical cancer radical surgery peritoneum subcutaneous tissue

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Microstructure investigation of dynamic recrystallization in hard machining: From thermodynamic irreversibility

Binxun LI, Xinzhi ZHANG, Song ZHANG

《机械工程前沿（英文）》 2021年第16卷第2期页码 315-330 doi: 10.1007/s11465-020-0612-4

摘要： The drastically changed thermal, mechanical, and chemical energies within the machined surface layer during hard machining tend to initiate microstructural alteration. In this paper, attention is paid to the introduction of thermodynamic potential to unravel the mechanism of microstructure evolution. First, the thermodynamic potential-based model expressed by the Helmholtz free energy was proposed for predicting the microstructure changes of serrated chip and the machined surface layer. Second, the proposed model was implemented into a validated finite element simulation model for cutting operation as a user-defined subroutine. In addition, the predicted irreversible thermodynamic state change in the deformation zones associated with grain size, which was reduced to less than 1 m from the initial size of 1.5 m on the machined surface, was provided for an in-depth explanation. The good consistency between the simulated results and experimental data validated the efficacy of the developed model. This research helps to provide further insight into the microstructure alteration during metal cutting.

关键词： thermodynamic irreversibility Helmholtz free energy microstructure evolution dynamic recrystallization hard milling

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Effect of magneto rheological damper on tool vibration during hard turning

P. Sam PAUL, A. S. VARADARAJAN

《机械工程前沿（英文）》 2012年第7卷第4期页码 410-416 doi: 10.1007/s11465-012-0341-4

摘要：

Recently, the concept of hard turning has gained considerable attention in metal cutting as it can apparently replace the traditional process cycle of turning, heat treating, and finish grinding for assembly of hard wear resistant steel parts. The present investigation aims at developing a magneto rheological (MR) fluid damper for suppressing tool vibration and promoting better cutting performance during hard turning. The magneto rheological Fluid acts as a viscoelastic spring with non-linear vibration characteristics that are controlled by the composition of the magneto rheological fluid, the shape of the plunger and the electric parameters of the magnetizing field. Cutting experiments were conducted to arrive at a set of electrical, compositional and shape parameters that can suppress tool vibration and promote better cutting performance during turning of AISI 4340 steel of 46 HRC with minimal fluid application using hard metal insert with sculptured rake face. It was observed that the use of MR fluid damper reduces tool vibration and improves the cutting performance effectively. Also commercialization of this idea holds promise to the metal cutting industry.

关键词： tool vibration magneto rheological damper hard turning surface finish tool wear

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Crack evolution of soft–hard composite layered rock-like specimens with two fissures under uniaxial compression

《结构与土木工程前沿（英文）》 2021年第15卷第6期页码 1372-1389 doi: 10.1007/s11709-021-0772-2

摘要： Acoustic emission and digital image correlation were used to study the spatiotemporal evolution characteristics of crack extension of soft and hard composite laminated rock masses (SHCLRM) containing double fissures under uniaxial compression. The effects of different rock combination methods and prefabricated fissures with different orientations on mechanical properties and crack coalescence patterns were analyzed. The characteristics of the acoustic emission source location distribution, and frequency changes of the crack evolution process were also investigated. The test results show that the damage mode of SHCLRM is related to the combination mode of rock layers and the orientation of fractures. Hard layers predominantly produce tensile cracks; soft layers produce shear cracks. The first crack always sprouts at the tip or middle of prefabricated fractures in hard layers. The acoustic emission signal of SHCLRM with double fractures has clear stage characteristics, and the state of crack development can be inferred from this signal to provide early warning for rock fracture instability. This study can provide a reference for the assessment of the fracture development status between adjacent roadways in SHCLRM in underground mines, as well as in roadway layout and support.

关键词： soft−hard composite layered rock mass double cracks crack evolution acoustic emission digital image correlation