Browsing by Author "Zhang, Kai"

Now showing 1 - 7 of 7
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    A unique biomimetic modification endows polyetherketoneketone scaffold with osteoinductivity by activating cAMP/PKA signaling pathway
    (AAAS, 2022) Yuan, Bo; Zhang, Yuxiang; Zhao, Rui; Lin, Hai; Yang, Xiao; Zhu, Xiangdong; Zhang, Kai; Mikos, Antonios G.; Zhang, Xingdong
    Osteoinductivity of a biomaterial scaffold can notably enhance the bone healing performance. In this study, we developed a biomimetic and hierarchically porous polyetherketoneketone (PEKK) scaffold with unique osteoinductivity using a combined surface treatment strategy of a sulfonated process and a nano bone-like apatite deposition. In a beagle intramuscular model, the scaffold induced bone formation ectopically after 12-week implantation. The better bone healing ability of the scaffold than the original PEKK was also confirmed in orthotopic sites. After culturing with bone marrow–derived mesenchymal stem cells (BMSCs), the scaffold induced osteogenic differentiation of BMSCs, and the new bone formation could be mainly depending on cell signaling through adenylate cyclase 9, which activates the cyclic adenosine monophosphate/protein kinase A signaling cascade pathways. The current work reports a new osteoinductive synthetic polymeric scaffold with its detailed molecular mechanism of action for bone repair and regeneration.
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    Compiling for software distributed-shared memory systems
    (2000) Zhang, Kai; Mellor-Crummey, John
    In this thesis, we explore the use of software distributed shared memory (SDSM) as a target communication layer for parallelizing compilers. We explore how to effectively exploit compiler-derived knowledge of sharing and communication patterns for regular access patterns to improve their performance on SDSM systems. We introduce two novel optimization techniques: compiler-restricted consistency which reduces the cost of false sharing, and compiler-managed communication buffers which, when used together with compiler-restricted consistency, reduce the cost of fragmentation. We focus on regular applications with wavefront computation and tightly-coupled sharing due to carried data dependence. Along with other types of compiler-assisted SDSM optimizations such as compiler-controlled eager update, our integrated compiler and run-time support provides speedups for wavefront computations on SDSM that rival those achieved previously only for loosely synchronous style applications. (Abstract shortened by UMI.)
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    Compiling for Software Distributed-Shared Memory Systems
    (2000-04-03) Zhang, Kai
    In this thesis, we explore the use of software distributed shared memory (SDSM) as a target communication layer for parallelizing compilers. ForSDSM to be effective for this purpose it must efficiently support both regular and irregular communication patterns. Previous studies have demonstrated techniques that enable SDSM to achieve performance that is competitive with hand-coded message passing for irregular applications. Here, we explore how to effectively exploit compiler-derived knowledge of sharing and communication patterns for regular access patterns to improve their performance on SDSM systems. We introduce two novel optimization techniques: compiler-restricted consistency which reduces the cost of false sharing, and compiler-managed communication buffers which, when used together with compiler-restricted consistency, reduce the cost of fragmentation. We focus on regular applications with wavefront computation and tightly-coupled sharing due to carried data dependence. Previous studies of regular applications all focus on loosely-coupled parallelism for which it is easier to achieve good performance. We describe point-to-point synchronization primitives we have developed that facilitate the parallelization of this type of applications on SDSM. Along with other types of compiler-assisted SDSM optimizations such as compiler-controlled eager update, our integrated compiler and run-time support provides speedups for wavefront computations on SDSM that rival those achieved previously only for loosely synchronous style applications. For example, we achieve a speed up of 11 out of 16 for SOR benchmark—a tightly-coupled computation based on wavefront, of a problem size of 4Kx4K. which compares favorably with the 14 out of 16 speed up which we obtain for Red Black SOR—a loosely-coupled computation, of the same problem size under the same hardware and software environment. With the NAS-BT application benchmark using the Class A problem size, we achieved an impressive boost of speedup, from 4 out of 16, to 10 out of 16, on SDSM as a result of the compiler and runtime optimizations we described here.
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    Evidence-based biomaterials research
    (Elsevier, 2022) Zhang, Kai; Ma, Bin; Hu, Kaiyan; Yuan, Bo; Sun, Xin; Song, Xu; Tang, Zhonglan; Lin, Hai; Zhu, Xiangdong; Zheng, Yufeng; García, Andrés J.; Mikos, Antonios G.; Anderson, James M.; Zhang, Xingdong
    The fast development of biomaterials science and engineering has generated significant number of studies and publications as well as tremendous amount of research data. A methodology is needed to translate such research data and results to validated scientific evidence. This article for the first time proposes the concept and methodology of evidence-based biomaterials research, which is to use evidence-based research approach represented by systematic reviews to generate evidence for answering scientific questions related to biomaterials. After briefly introducing the advancement of biomaterials since 1950s, the scientific and engineering nature of biomaterials are discussed along with the roadmap of biomaterials translation from basic research to commercialized medical products, and the needs of scientific evidence. Key information of the evidence-based approach such as its origination from evidence-based medicine, levels of evidence, systematic review and meta-analysis, differences between systematic and narrative reviews is then highlighted. Applications with a step-by-step procedure of conducting evidence-based biomaterials research, three examples of biomaterials research using evidence-based approach to generate scientific evidence, and opportunities and challenges of evidence-based biomaterials research are presented. With its notable impact on the practice of medicine, the evidence-based approach is also expected to make influential contributions to the biomaterials field.
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    High Strength Titanium with Fibrous Grain for Advanced Bone Regeneration
    (Wiley, 2023) Wang, Ruohan; Wang, Mingsai; Jin, Rongrong; Wang, Yanfei; Yi, Min; Li, Qinye; Li, Juan; Zhang, Kai; Sun, Chenghua; Nie, Yu; Huang, Chongxiang; Mikos, Antonios G.; Zhang, Xingdong
    Pure titanium is widely used in clinical implants, but its bioinert properties (poor strength and mediocre effect on bone healing) limit its use under load-bearing conditions. Modeling on the structure of collagen fibrils and specific nanocrystal plane arrangement of hydroxyapatite in the natural bone, a new type of titanium (Ti) with a highly aligned fibrous-grained (FG) microstructure is constructed. The improved attributes of FG Ti include high strength (≈950 MPa), outstanding affinity to new bone growth, and tight bone-implant contact. The bone-mimicking fibrous grains induce an aligned surface topological structure conducive to forming close contact with osteoblasts and promotes the expression of osteogenic genes. Concurrently, the predominant Ti(0002) crystal plane of FG Ti induces the formation of hydrophilic anatase titanium oxide layers, which accelerate biomineralization. In conclusion, this bioinspired FG Ti not only proves to show mechanical and bone-regenerative improvements but it also provides a new strategy for the future design of metallic biomaterials.
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    The role of hydrogen in the energy transition of the oil and gas industry
    (Elsevier, 2024) Zhang, Kai; He, Liu; Jiang, Liangliang; Jiang, Shu; Yu, Ruyang; Lau, Hon Chung; Xie, Congjiao; Chen, Zhangxin
    Hydrogen, primarily produced from steam methane reforming, plays a crucial role in oil refining, and provides a solution for the oil and gas industry's long-term energy transition by reducing CO2 emissions. This paper examines hydrogen’s role in this transition. Firstly, experiences from oil and gas exploration, including in-situ gasification, can be leveraged for hydrogen production from subsurface natural hydrogen reservoirs. The produced hydrogen can serve as fuel for generating steam and heat for thermal oil recovery. Secondly, hydrogen can be blended into gas for pipeline transportation and used as an alternative fuel for oil and gas hauling trucks. Additionally, hydrogen can be stored underground in depleted gas fields. Lastly, oilfield water can be utilized for hydrogen production using geothermal energy from subsurface oil and gas fields. Scaling up hydrogen production faces challenges, such as shared use of oil and gas infrastructures, increased carbon tax for promoting blue hydrogen, and the introduction of financial incentives for hydrogen production and consumption, hydrogen leakage prevention and detection.
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    Translation of biomaterials from bench to clinic
    (Elsevier, 2022) Zhang, Kai; Mikos, Antonios G.; Reis, Rui L.; Zhang, Xingdong
    Scientific research originates from curiosity and interests. Translational research of biomaterials should always focus on addressing specific needs of the targeted clinical applications. The guest editors of this special issue hope that the included articles have provided cutting-edge biomaterials research as well as insights of the translation of biomaterials from bench to clinic.