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design Improvements and Validation of a Novel Fully 3d Printed Analogue Lumbar Spine Motion Segment

Journal of Bionic Engineering 2024年第3期21卷 1388-1396页

作者： Siril Teja dukkipati mark driscoll Musculoskeletal Biomechanics Research Lab Department of Mechanical EngineeringMcGill University845 Sherbrooke St.W(163)MontréalQCH3A 0C3Canada Orthopaedic Research Lab Montreal General Hospital1650 Cedar Ave(LS1.409)MontréalQCH3G 1A4Canada

Spine biomechanical testing methods in the past few decades have not evolved beyond employing either cadaveric studies or finite element modeling ***,both these approaches may have inherent cost and time *** studies are the present gold standard for spinal implant design and regulatory approval,but they introduce significant variability in measurements across patients,often requiring large sample *** element modeling demands considerable expertise and can be computationally expensive when complex geometry and material nonlinearity are *** analogue spine models could complement these traditional methods as a low-cost and high-fidelity alternative.A fully 3d printable L-S1 analogue spine model with ligaments is developed and validated in this *** stiffness of the model under pure bending loading in flexion-extension,Lateral Bending(LB)and Axial Rotation(AR)is evaluated and compared against historical ex vivo and in silico ***,the effect of interspinous,intertransverse ligaments and the Thoracolumbar Fascia(TLF)on spinal stiffness is evaluated by systematic construction of the *** flexion,model Range of Motion(ROM)was 12.92±0.11°(ex vivo:16.58°,in silico:12.96°)at *** LB,average ROM was 13.67±0.12°at 7.5 Nm(ex vivo:15.21±1.89°,in silico:15.49±0.23°).Similarly,in AR,average ROM was 17.69±2.12°at 7.5Nm(ex vivo:14.12±0.31°,in silico:15.91±0.28°).The addition of interspinous and intertransverse ligaments increased both flexion and LB stiffnesses by approximately 5%.Addition of TLF showed increase in flexion and AR stiffnesses by 29%and 24%,*** novel model can reproduce physiological ROMs with high repeatability and could be a useful open-source tool in spine biomechanics.

关键词： Lumbar spine 3d printing Intervertebral disc Biomechanical testing Spine mechanics

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Analysis of the inflection points of height-diameter models

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Forest Ecosystems 2024年第4期11卷 414-422页

作者： Tzeng Yih Lam mark J.ducey department of Forest Resources Management Faculty of ForestryThe University of British Columbia2045-2424 Main MallVancouverBCV6T 1Z4 Canada department of Natural Resources and the Environment University of New Hampshire114 James HallDurhamNH 03824USA

The inflection point is an important feature of sigmoidal height-diameter(H-d)*** is often cited as one of the properties favoring sigmoidal model ***,there are very few studies analyzing the inflection points of H-d *** goals of this study were to theoretically and empirically examine the behaviors of inflection points of six common H-d models with a regional *** six models were the Wykoff(WYK),Schumacher(SCH),Curtis(CUR),HossfeldⅣ(HOS),von Bertalanffy-Richards(VBR),and Gompertz(GPZ)*** models were first fitted in their base forms with tree species as random effects and were then expanded to include functional traits and spatial *** distributions of the estimated inflection points were similar between the two-parameter models WYK,SCH,and CUR,but were different between the threeparameter models HOS,VBR,and *** produced some of the largest inflection *** and VBR produced concave H-d curves without inflection points for 12.7%and 39.7%of the tree *** species or decreasing shade tolerance resulted in larger inflection *** trends in the estimated inflection points of HOS and VBR were entirely opposite across the ***,HOS could produce concave H-d curves for portions of the *** on the studied behaviors,the choice between two-parameter models may not *** recommend comparing seve ral three-parameter model forms for consistency in estimated inflection points before deciding on *** sigmoidal models to have inflection points does not necessarily mean that they will produce fitted curves with *** study highlights the need to integrate analysis of inflection points into modeling H-d relationships.

关键词： Concavity Forest inventory and analysis Generalized height-diameter models Growth functions Height-diameter functions Mixed-effects modeling Points of inflection Species-specific models

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The efficacy of vitamin E in preventing arthrofibrosis after joint replacement

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Animal Models and Experimental Medicine 2024年第2期7卷 145-155页

作者： Yingfang Fan Jean Yuh Sashank Lekkala Mehmet d.Asik Andrew Thomson Madeline McCanne mark A.Randolph Antonia F.Chen Ebru Oral Harris Orthopaedic Laboratory Department of Orthopaedic SurgeryMassachusetts General HospitalBostonMassachusettsUSA department of Orthopaedic Surgery Harvard Medical SchoolBostonMassachusettsUSA department of Surgery Harvard Medical SchoolBostonMassachusettsUSA department of Orthopaedic Surgery Brigham and Women's HospitalBostonMassachusettsUSA

Background:Arthrofibrosis is a joint disorder characterized by excessive scar formation in the joint *** E is an antioxidant with potential anti-fibroblastic *** aim of this study was to establish an arthrofibrosis rat model after joint replacement and assess the effects of vitamin E supplementation on joint ***:We simulated knee replacement in 16 male Sprague–dawley *** immobilized the surgical leg with a suture in full *** control groups were killed at 2 and 12 weeks(n=5 per group),and the test group was supplemented daily with vitamin E(0.2 mg/mL)in their drinking water for 12 weeks(n=6).We performed histological staining to investigate the presence and severity of *** staining andα2-macroglobulin(α2M)enzyme-linked immunosorbent assay(ELISA)were used to assess local and systemic *** weight bearing(total internal reflection)and range of motion(ROM)were collected for functional ***:The ROM and weight-bearing symmetry decreased after the procedure and recovered slowly with still significant deficit at the end of the study for both *** analysis confirmed fibrosis in both lateral and posterior periarticular *** E supplementation showed a moderate anti-inflammatory effect on the local and systemic *** vitamin E group exhibited significant improvement in ROM and weight-bearing symmetry at day 84 compared to the control ***:This model is viable for simulating arthrofibrosis after joint *** E may benefit postsurgical arthrofibrosis,and further studies are needed for dosing requirements.

关键词： arthrofibrosis range of motion total knee arthroplasty vitamin E

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Biopolymer stabilization of clayey soil

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第7期16卷 2801-2812页

作者： Mahdieh Azimi Amin Soltani Mehdi Mirzababaei mark B.Jaksa Nanjappa Ashwath College of Engineering and Aviation School of Engineering and TechnologyCQUniversityMelbourneVIC 3000Australia Institute of Innovation Science and Sustainabilityand Future Regions Research CenterFederation UniversityChurchillVIC 3842Australia department of Infrastructure Engineering Faculty of Engineering and Information TechnologyThe University of MelbourneParkvilleVIC 3010Australia School of Architecture and Civil Engineering The University of AdelaideAdelaideSA 5005Australia School of Health Medical and Applied SciencesCQUniversityRockhamptonQLD 4701Australia

This study investigates the efficacy of sodium alginate(SA),xanthan gum(XG),guar gum(GG)and chitosan(CS)d each applied at five different solid biopolymer-to-water mass ratios(or dosages)and cured for 7 d and 28 d d on the unconfined compressive strength(UCS)performance of a high plasticity clayey ***,on identifying the optimum biopolymer-treatment scenarios,their performance was compared against conventional stabilization using hydrated *** a given curing time,the UCS for all biopolymers followed a riseefall trend with increasing biopolymer dosage,peaking at an optimum dosage and then subsequently decreasing,such that all biopolymer-stabilized samples mobilized higher UCS values compared to the unamended *** optimum dosage was found to be 1.5%for SA,XG and CS,while a notably lower dosage of 0.5%was deemed optimum for ***,for a given biopolymer type and dosage,increasing the curing time from 7 d to 28 d further enhanced the UCS,with the achieved improvements being generally more pronounced for XG-and CS-treated *** of the investigated biopolymers was able to produce UCS improvements equivalent to those obtained by the 28-d soilelime samples;however,the optimum XG,GG and CS dosages,particularly after 28 d of curing,were easily able to replicate 7-d lime stabilization outcomes achieved with as high as twice the soil’s lime ***,the fundamental principles of clay chemistry,in conjunction with the soil mechanics framework,were employed to identify and discuss the clayebiopolymer stabilization mechanisms.

关键词： Soil stabilization High plasticity clay Biopolymer dosage Hydrated lime Curing time Unconfined compressive strength(UCS)

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A three-dimensional feature extraction-based method for coal cleat characterization using X-ray μCT and its application to a Bowen Basin coal specimen

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第1期16卷 153-166页

作者： Yulai Zhang Matthew Tsang mark Knackstedt Michael Turner Shane Latham Euan Macaulay Rhys Pitchers ARC Training Centre for M3d Innovation Research School of PhysicsAustralian National UniversityCanberraACT2601Australia department of Materials Physics Research School of PhysicsAustralian National UniversityCanberraACT2601Australia Anglo American Steelmaking Coal BrisbaneQLD4000Australia SCT Operations Pty Ltd. WollongongNSW2500Australia

Cleats are the dominant micro-fracture network controlling the macro-mechanical behavior of *** understanding of the spatial characteristics of cleat networks is therefore important to the coal mining *** fracture networks(dFNs)are increasingly used in engineering analyses to spatially model fractures at various *** reliability of coal dFNs largely depends on the confidence in the input cleat *** of these parameters can be made from image-based three-dimensional(3d)characterization of coal cleats using X-ray micro-computed tomography(m CT).One key step in this process,after cleat extraction,is the separation of individual cleats,without which the cleats are a connected network and statistics for different cleat sets cannot be *** this paper,a feature extraction-based image processing method is introduced to identify and separate distinct cleat groups from 3d X-ray m CT ***(filters)representing explicit cleat features of coal are built and cleat separation is successfully achieved by convolutional operations on 3d coal *** new method is applied to a coal specimen with 80 mm in diameter and 100 mm in length acquired from an Anglo American Steelmaking Coal mine in the Bowen Basin,Queensland,*** is demonstrated that the new method produces reliable cleat separation capable of defining individual cleats and preserving 3d topology after ***-parallel fractures are also identified and separated,which has his-torically been challenging to delineate and rarely reported.A variety of cleat/fracture statistics is measured which not only can quantitatively characterize the cleat/fracture system but also can be used for dFN ***,variability and heterogeneity with respect to the core axis are *** heterogeneity is observed and suggests that the representative elementary volume(REV)of the cleat groups for engineering purposes may be a complex problem requ

关键词： Cleat separation Cleat statistics Feature extraction discrete fracture network(dFN)modeling

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Importance of gastrin in the pathogenesis and treatment of gastric tumors

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World Journal of Gastroenterology 2009年第1期15卷 1-16页

作者： Michael d Burkitt Andrea Varro d.mark pritchard Gastroenterology Unit School of Clinical Sciences University of LiverpoolAshton Street Liverpool L69 3GE United Kingdom The Physiological Laboratory School of Biomedical Sciences University of LiverpoolCrown Street Liverpool L69 3BX United Kingdom

In addition to regulating acid secretion, the gastric antral hormone gastrin regulates several important cellular processes in the gastric epithelium including proliferation, apoptosis, migration, invasion, tissue remodelling and angiogenesis. Elevated serum concentrations of this hormone are caused by many conditions, particularly hypochlorhydria (as a result of autoimmune or Helicobacter pylori (H pylori)-induced chronic atrophic gastritis or acid suppressing drugs) and gastrin producing tumors (gastrinomas). There is now accumulating evidence that altered local and plasma concentrations of gastrin may play a role during the development of various gastric tumors. In the absence of H pylori infection, marked hypergastrinemia frequently results in the development of gastric enterochromaffi n cell-like neuroendocrine tumors and surgery to remove the cause of hypergastrinemia may lead to tumor resolution in this condition. In animal models such as transgenic INS-GAS mice, hypergastrinemia has also been shown to act as a cofactor with Helicobacter infection during gastric adenocarcinoma development. However, it is currently unclear as to what extent gastrin also modulates human gastric adenocarcinoma development. Therapeutic approaches targeting hypergastrinemia,such as immunization with G17dT, have been evaluated for the treatment of gastric adenocarcinoma, with some promising results. Although the mild hypergastrinemia associated with proton pump inhibitor drug use has been shown to cause ECL-cell hyperplasia and to increase H pylori-induced gastric atrophy, there is currently no convincing evidence that this class of agents contributes towards the development of gastric neuroendocrine tumors or gastric adenocarcinomas in human subjects.

关键词： Helicobacter py/ori Hypergastrinemia Neuroendocrine Gastric carcinoma Proton pumpinhibitor

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does a large prostate size,small lesion volume,or long needle distance from the probe to the lesion reduce magnetic resonance imaging–targeted cancer detection?

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Current Urology 2024年第2期18卷 144-147页

作者： mark d.Bevill Justin N.drobish Kevin J.Flynn Maheen Rajput Catherine Metz Chad R.Tracy Paul T.Gellhaus department of Urology University of Iowa Carver College of MedicineIowa CityIAUSA department of Radiology University of Iowa Carver College of MedicineIowa CityIAUSA

Background:We aimed to evaluate whether large prostate size,small lesion volume,or long lesion distance from the ultrasound probe tip would decrease cancer detection in transrectal magnetic resonance imaging(MRI)–targeted *** and methods:Patients who underwent MRI-targeted biopsy at our institution between May 2017 and August 2019 were enrolled in a prospective *** to 5 cores were obtained from≥2 prostate imaging reporting and data system v2 lesions.A multivariable model was created that included needle distance to the lesion,prostate specific antigen,prostate imaging reporting and data system,lesion volume,and prostate ***:A total of 377 patients with 533 lesions underwent a biopsy during the study period.A total of 233(44%)lesions were positive for prostate cancer,and 173(32%)lesions had clinically significant prostate *** mean needle distance to the lesion was 11.7mm(interquartile range,7.6–15.5mm).The likelihood of obtaining a positive core on biopsy decreased as the distance fromthe ultrasound probe increased for all prostate cancers and clinically significant prostate cancer(p=0.018 and p=0.004,respectively).Every 10mmfrom the rectum,there was an 8%–10%decrease in the rate of cancer ***,as the prostate volume increased,the odds of obtaining a positive core also decreased(p=0.039).There was no significant association between the lesion size and amount of cancer obtained on ***:Our data showed that transrectal MRI-targeted biopsy cancer detection modestly decreased the lesion from the ultrasound probe and with a large prostate volume but could not prove that lesion volume was a significant predictor of the amount of cancer detected.

关键词： Prostate cancer Biopsy Magnetic resonance imaging

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Measuring Pedestrian Stress Response (MPSR) Using Wearable Technologies

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Journal of Transportation Technologies 2024年第2期14卷 224-235页

作者： Ishita dash Rachael Anne Muscatello mark d. Abkowitz Ella R. Mostoller Mike Sewell department of Civil and Environmental Engineering Vanderbilt University 2301 Vanderbilt Place Nashville USA department of Psychiatry and Behavioral Sciences SENSE Lab Vanderbilt University Medical Center 1211 Medical Center Drive Nashville USA Gresham Smith 111 West Main Street Suite 201 Louisville USA

Walkability is an essential aspect of urban transportation systems. Properly designed walking paths can enhance transportation safety, encourage pedestrian activity, and improve community quality of life. This, in turn, can help achieve sustainable development goals in urban areas. This pilot study uses wearable technology data to present a new method for measuring pedestrian stress in urban environments and the results were presented as an interactive geographic information system map to support risk-informed decision-making. The approach involves analyzing data from wearable devices using heart rate variability (RMSSd and slope analysis) to identify high-stress locations. This data-driven approach can help urban planners and safety experts identify and address pedestrian stressors, ultimately creating safer, more walkable cities. The study addresses a significant challenge in pedestrian safety by providing insights into factors and locations that trigger stress in pedestrians. during the pilot study, high-stress pedestrian experiences were identified due to issues like pedestrian-scooter interaction on pedestrian paths, pedestrian behavior around high foot traffic areas, and poor visibility at pedestrian crossings due to inadequate lighting.

关键词： Wearable Technology Walkability Built Environment Pedestrian Safety

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A 3d In-vitro model of the human dentine interface shows long-range osteoinduction from the dentine surface

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International Journal of Oral Science 2024年第2期16卷 225-237页

作者： William Macalester Asme Boussahel Rafael O.Moreno-Tortolero mark R.Shannon Nicola West darryl Hill Adam Perriman School of Cellular and Molecular Medicine Biomedical Sciences BuildingUniversity of BristolUniversity WalkBristolUnited Kingdom Bristol Centre for Functional Nanomaterials HH Wills Physics LaboratoryUniversity of BristolTyndall AvenueBristolUnited Kingdom Centre for Protolife Research School of ChemistryUniversity of BristolCantocks CloseBristolUnited Kingdom Max Planck-Bristol Centre for Minimal Biology School of ChemistryUniversity of BristolBristolUnited Kingdom Periodontology Bristol Dental SchoolUniversity of BristolLower Maudlin StreetBristolUnited Kingdom

Emerging regenerative cell therapies for alveolar bone loss have begun to explore the use of cell laden hydrogels for minimally invasive surgery to treat small and spatially complex maxilla-oral ***,the oral cavity presents a unique and challenging environment for in vivo bone tissue engineering,exhibiting both hard and soft periodontal tissue as well as acting as key biocenosis for many distinct microbial communities that interact with both the external environment and internal body systems,which will impact on cell fate and subsequent treatment ***,we design and bioprint a facile 3d in vitro model of a human dentine interface to probe the effect of the dentine surface on human mesenchymal stem cells(hMSCs)encapsulated in a microporous hydrogel *** demonstrate that the dentine substrate induces osteogenic differentiation of encapsulated hMSCs,and that both dentine andβ-tricalcium phosphate substrates stimulate extracellular matrix production and maturation at the gel-media interface,which is distal to the gel-substrate *** findings demonstrate the potential for long-range effects on stem cells by mineralized surfaces during bone tissue engineering and provide a framework for the rapid development of 3d dentine-bone interface models.

关键词： interface den surface

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Anneal-free ultra-low loss silicon nitride integrated photonics

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Light(Science & Applications) 2024年第8期13卷 1565-1577页

作者： debapam Bose mark W.Harrington Andrei Isichenko Kaikai Liu Jiawei Wang Nitesh Chauhan Zachary L.Newman daniel J.Blumenthal department of Electrical and Computer Engineering University of California Santa BarbaraSanta BarbaraCA 93106USA Octave Photonics LouisvilleCO 80027USA

Heterogeneous and monolithic integration of the versatile low-loss silicon nitride platform with low-temperature materials such as silicon electronics and photonics,III–V compound semiconductors,lithium niobate,organics,and glasses has been inhibited by the need for high-temperature annealing as well as the need for different process flows for thin and thick *** techniques are needed to maintain the state-of-the-art losses,nonlinear properties,and CMOS-compatible processes while enabling this next generation of 3d silicon nitride *** report a significant advance in silicon nitride integrated photonics,demonstrating the lowest losses to date for an anneal-free process at a maximum temperature 250℃,with the same deuterated silane based fabrication flow,for nitride and oxide,for an order of magnitude range in nitride thickness without requiring stress mitigation or *** report record low anneal-free losses for both nitride core and oxide cladding,enabling 1.77 dBm^(-1) loss and 14.9 million Q for 80 nm nitride core waveguides,more than half an order magnitude lower loss than previously reported sub 300℃ *** 800 nm-thick nitride,we achieve as good as 8.66 dBm^(-1) loss and 4.03 million Q,the highest reported Q for a low temperature processed resonator with equivalent device area,with a median of loss and Q of 13.9 dBm^(-1) and 2.59 million each *** demonstrate laser stabilization with over 4 orders of magnitude frequency noise reduction using a thin nitride reference cavity,and using a thick nitride micro-resonator we demonstrate OPO,over two octave supercontinuum generation,and four-wave mixing and parametric gain with the lowest reported optical parametric oscillation threshold per unit resonator *** results represent a significant step towards a uniform ultra-low loss silicon nitride homogeneous and heterogeneous platform for both thin and thick waveguides capable of linear and nonlinear photonic circuits and

关键词： resonator thick free

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