Comparative Effectiveness of Laterally Placed Expandable versus Static Interbody Spacers: A 1-Year Follow-Up Radiographic and Clinical Outcomes Study

Li Yan Michael,Frisch Richard Francis,Huang Zheng,Towner James Edward,Li Yan Icy,Edsall Amber Lynn,Ledonio Charles 대한척추외과학회 2021 Asian Spine Journal Vol.15 No.1

Study Design: Retrospective chart review.Purpose: This study compared the clinical and radiographic outcomes of patients treated with expandable and static interbody spacers following minimally invasive lateral lumbar interbody fusion (MIS-LLIF) with 12-month follow-up.Overview of Literature: A common surgical option for the treatment of degenerative disk disease (DDD) is MIS-LLIF using static or expandable spacers to restore disk height (DH), neuroforaminal height (NH), and segmental lordosis. Static spacers may require excessive trialing and aggressive impaction, potentially leading to endplate disruption and subsidence. Expandable spacers allow for in situ expansion to help address complications associated with static spacers.Methods: This is an Institutional Review Board-exempt review of 69 patients (static, n=32; expandable, n=37) diagnosed with DDD who underwent MIS-LLIF at 1–2 contiguous level(s) using static or expandable spacers. Radiographic and clinical outcomes were collected and compared at pre- and postoperative time points up to 12 months.Results: The expandable group had a significantly higher mean change in Visual Analog Scale (VAS) scores at 6 weeks, 6 months, and 12 months vs. static (∆VAS at 12 months: expandable, 6.7±1.3; static, 5.1±2.6). Mean improvement of Oswestry Disability Index (ODI) scores at 3, 6, and 12 months were significantly better for the expandable group vs. static (∆ODI at 12 months: expandable, 63.2±13.2; static, 29.8±23.4). Mean DH and NH significantly increased at final follow-up for both groups, with no significant difference in DH improvement between groups. The expandable mean NH improvement at 6 weeks and 6 months was significantly greater vs. static. Segmental lordosis significantly improved in the expandable group at all time intervals vs static. Subsidence rate at 12 months was significantly lower in the expandable group (1/46, 2.2%) vs. static (12/37, 32.4%).Conclusions: Expandable spacers resulted in a significantly lower subsidence rate, improve segmental lordosis, and VAS and ODI outcomes at 12 months vs. static.

Development of self-centring energy-dissipative rocking columns equipped with SMA tension braces

Yan-Wen Li,Michael C.H. Yam,Ping Zhang,Ke Ke,Yan-Bo Wang 국제구조공학회 2022 Structural Engineering and Mechanics, An Int'l Jou Vol.82 No.5

Energy-dissipative rocking (EDR) columns are a class of seismic mitigation device capable of dissipating seismic energy and preventing weak-story failure of moment resisting frames (MRFs). An EDR consists of two hinge-supported steel columns interconnected by steel dampers along its height. Under earthquakes, the input seismic energy can be dissipated by plastic energy of the steel dampers in the EDR column. However, the unrecoverable plastic deformation of steel dampers generally results in residual drifts in the structural system. This paper presents a proof-of-concept study on an innovative device, namely self-centring energy-dissipative rocking (SC-EDR) column, aiming at enabling self-centring capability of the EDR column by installing a set of shape memory alloy (SMA) tension braces. The working mechanism of the SC-EDR column is presented in detail, and the feasibility of the new device is carefully examined via experimental and numerical studies considering the parameters of the SMA bar diameter and the steel damper plate thickness. The seismic responses including load carrying capacities, stress distributions, base rocking behaviour, source of residual deformation, and energy dissipation are discussed in detail. A rational combination of the steel damper and the SMA tension braces can achieve excellent energy dissipation and self-centring performance.

Shear resistance of corrugated web steel beams with circular web openings: Test and machine learning-based prediction

Yan-Wen Li,Guo-Qiang Li,Lei Xiao,Michael C. H. Yam,JingZhou Zhang 국제구조공학회 2023 Steel and Composite Structures, An International J Vol.47 No.1

This paper presents an investigation on the shear resistance of corrugated web steel beams (CWBs) with a circular web opening. A total of five specimens with different diameters of web openings were designed and tested with vertical load applied on the top flange at mid-span. The ultimate strengths, failure modes, and load versus middle displacement curves were obtained from the tests. Following the tests, numerical models of the CWBs were developed and validated against the test results. The influence of the web plate thickness, steel grade, opening diameter, and location on the shear strength of the CWBs was extensively investigated. An XGBoost machine learning model for shear resistance prediction was trained based on 256 CWB samples. The XGBoost model with optimal hyperparameters showed excellent accuracy and exceeded the accuracy of the available design equations. The effects of geometric parameters and material properties on the shear resistance were evaluated using the SHAP method.

Seismic collapse risk of RC frames with irregular distributed masonry infills

Yan-Wen Li,Michael C.H. Yam,Ke Cao 국제구조공학회 2020 Structural Engineering and Mechanics, An Int'l Jou Vol.76 No.3

Masonry infills are normally considered as non-structural elements in design practice, therefore, the interaction between the bounding frame and the strength contribution of masonry infills is commonly ignored in the seismic analysis work of the RC frames. However, a number of typical RC frames with irregular distributed masonry infills have suffered from undesirable weak-story failure in major earthquakes, which indicates that ignoring the influence of masonry infills may cause great seismic collapse risk of RC frames. This paper presented the investigation on the risk of seismic collapse of RC frames with irregularly distributed masonry infills through a large number of nonlinear time history analyses (NTHAs). Based on the results of NTHAs, seismic fragility curves were developed for RC frames with various distribution patterns of masonry infills. It was found that the existence of masonry infills generally reduces the collapse risk of the RC frames under both frequent happened and very strong earthquakes, however, the severe irregular distribution of masonry infills, such as open ground story scenario, results in great risk of forming a weak story failure. The strong-column weak-beam (SCWB) ratio has been widely adopted in major seismic design codes to control the potential of weak story failures, where a SCWB ratio value about 1.2 is generally accepted as the lower limit. In this study, the effect of SCWB ratio on inter-story drift distribution was also parametrically investigated. It showed that improving the SCWB ratio of the RC frames with irregularly distributed masonry infills can reduce inter-story drift concentration index under earthquakes, therefore, prevent weak story failures. To achieve the same drift concentration index limit of the bare RC frame with SCWB ratio of about 1.2, which is specified in ACI318-14, the SCWB ratio of masonry-infilled RC frames should be no less than 1.5. For the open ground story scenario, this value can be as high as 1.8.

Stimulated Release of Size‐Selected Cargos in Succession from Mesoporous Silica Nanoparticles

Wang, Cheng,Li, Zongxi,Cao, Dennis,Zhao, Yan‐,Li,Gaines, Justin W.,Bozdemir, O. Altan,Ambrogio, Michael W.,Frasconi, Marco,Botros, Youssry Y.,Zink, Jeffrey I.,Stoddart, J. Fraser WILEY‐VCH Verlag 2012 Angewandte Chemie Vol.124 No.22

<P><B>Zwei Fliegen mit einer Klappe</B>: Die kovalente Bindung von β‐Cyclodextrin (gelb; siehe Bild) an mesoporöse Siliciumdioxid‐Nanopartikel (MSNs) ergibt ein duales Freisetzungssystem, das mit unterschiedlich großen Wirkstoffen (blaue und rote Kugeln) beladen werden kann, die sich auf verschiedene Stimuli hin nacheinander freisetzen lassen. Die kleineren Moleküle werden durch Absenken des pH‐Wertes freigesetzt, die größeren nach Abspaltung der Cyclodextrine von der MSN‐Oberfläche.</P>

Cretaceous beetles of the Jinju Formation (Coleoptera): An overview of the Jinju Formation, its coleopteran diversity, and past and future research

Lee Soo Bin,Li Yan-Da,Cai Chenyang,Engel Michael S.,Nam Gi Soo,Park Jong Kyun,Nel André,Jenkins Shaw Josh,Jouault Corentin,Legalov Andrei,Kundrata Robin 한국응용곤충학회 2024 Journal of Asia-Pacific Entomology Vol.27 No.2

Several Coleoptera fossils, including Coptoclavidae, Elateridae, Ommatidae, and Staphylinidae, were previously described from the Jinju Formation (Albian), South Korea. However, numerous beetle fossils require further research to fully understand the biodiversity of this important Cretaceous deposit. In this study, we present an overview of the diversity of Coleoptera from the Jinju Formation. Future studies on beetles of the Jinju For mation will be divided into several parts corresponding to the major lineages found in this Albian deposit. In this first part, we introduce the geological context, review previous studies related to Coleoptera fossils from the Jinju Formation, and present specimens that will undergo detailed examination in subsequent papers.