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Long-term monitoring of cycles in Clethrionomys rutilus in the Yukon boreal forest

Integrative Zoology 2024年第1期19卷 27-36页

作者： Charles J.KREBS Alice J.KENNEY B.Scott GILBERT Rudy BOONSTRA Department of Zoology University of British ColumbiaVancouverBritish ColumbiaCanada Renewable Resources Management Program Yukon UniversityWhitehorseYukonCanada Department of Biological Sciences University of Toronto ScarboroughTorontoOntarioCanada

Baseline studies of small rodent populations in undisturbed ecosystems are rare.We report here 50 years of mon-itoring and experimentation in Yukon of a dominant rodent species in the North American boreal forest,the red-backed vole Clethrionomys rutilus.These voles breed in summer,weigh 20–25 g,and reach a maximum density of 20 to 25 per ha.Their populations have shown consistent 3–4-year cycles for the last 50 years with the only change being that peak densities averaged 8/ha until 2000 and 18/ha since that year.During the last 25 years,we have measured food resources,predator numbers,and winter weather,and for 1-year social interactions,to estimate their contribution to changes in the rate of summer increase and the rate of overwinter decline.All these potential limiting factors could contribute to changes in density,and we measured their relative contributions statistically with multiple regressions.The rate of winter decline in density was related to both food supply and winter severity.The rate of summer increase was related to summer berry crops and white spruce cone production.No measure of predator numbers was related to winter or summer changes in vole abundance.There was a large signal of climate change effects in these populations.There is no density dependence in summer population growth and only a weak one in winter population declines.None of our results provide a clear understanding of what generates 3–4-year cycles in these voles,and the major missing piece may be an understanding of social interactions at high density.

关键词： boreal forest climate change density dependence population cycles predation winter severity

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A thermodynamic perspective on electrode poisoning in solid oxide fuel cells

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International Journal of Minerals,Metallurgy and Materials 2024年第6期31卷 1449-1455页

作者： Kevin Huang Department of Mechanical Engineering University of South CarolinaColumbiaUSA

A critical challenge to the commercialization of clean and high-efficiency solid oxide fuel cell(SOFC)technology is the insuf-ficient stack lifespan caused by a variety of degradation mechanisms,which are associated with cell components and chemical feedstocks.Cell components related degradation refers to thermal/chemical/electrochemical deterioration of cell materials under operating conditions,whereas the latter regards impurities in feedstocks of oxidant(air)and reductant(fuel).This article provides a thermodynamic perspective on the understanding of the impurities-induced degradation mechanisms in SOFCs.The discussion focuses on using thermodynamic ana-lysis to elucidate poisoning mechanisms in cathodes by impurity species such as Cr,CO_(2),H_(2)O,and SO_(2) and in the anode by species such as S(or H_(2)S),SiO_(2),and P_(2)(or PH_(3)).The author hopes the presented fundamental insights can provide a theoretical foundation for search-ing for better technical solutions to address the critical degradation challenges.

关键词： impurities air fuel reaction activity

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Engineering Nano/Microscale Chiral Self‑Assembly in 3D Printed Constructs

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Nano-Micro Letters 2024年第3期16卷 313-332页

作者： Mohsen Esmaeili Ehsan Akbari Kyle George Gelareh Rezvan Nader Taheri‑Qazvini Monirosadat Sadati Department of Chemical Engineering University of South CarolinaColumbiaSC 29208USA TA Instruments Waters LLCNew CastleDE 19720USA Biomedical Engineering Program University of South CarolinaColumbiaSC 29208USA

Helical hierarchy found in biomolecules like cellulose,chitin,and collagen underpins the remarkable mechanical strength and vibrant colors observed in living organisms.This study advances the integration of helical/chiral assembly and 3D printing technology,providing precise spatial control over chiral nano/microstructures of rod-shaped colloidal nanoparticles in intricate geometries.We designed reactive chiral inks based on cellulose nanocrystal(CNC)suspensions and acrylamide monomers,enabling the chiral assembly at nano/microscale,beyond the resolution seen in printed materials.We employed a range of complementary techniques including Orthogonal Superposition rheometry and in situ rheo-optic measurements under steady shear rate conditions.These techniques help us to understand the nature of the nonlinear flow behavior of the chiral inks,and directly probe the flow-induced microstructural dynamics and phase transitions at constant shear rates,as well as their post-flow relaxation.Furthermore,we analyzed the photo-curing process to identify key parameters affecting gelation kinetics and structural integrity of the printed object within the supporting bath.These insights into the interplay between the chiral inks self-assembly dynamics,3D printing flow kinematics and photopolymerization kinetics provide a roadmap to direct the out-of-equilibrium arrangement of CNC particles in the 3D printed filaments,ranging from uniform nematic to 3D concentric chiral structures with controlled pitch length,as well as random orientation of chiral domains.Our biomimetic approach can pave the way for the creation of materials with superior mechanical properties or programable photonic responses that arise from 3D nano/microstructure and can be translated into larger scale 3D printed designs.

关键词： Directed chiral self-assembly Cellulose nanocrystals Bioinspired nanocomposite 3D printing Rheology

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Flow structure and shear stress in the presence of both ice cover on water surface and leafless vegetation in channel bed

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Journal of Hydrodynamics 2024年第2期36卷 340-354页

作者： Mahboubeh Barahimi Jueyi Sui School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

This study aimed to investigate the previously unexplored effects of ice cover and submerged vegetation on flow structure.Experiments were undertaken under both open channel and ice-covered flow conditions.The bed material consisted of three non-uniform sands.The findings revealed that when vegetation patches were present on the bed and an ice cover was present,the velocity profiles exhibited a distinctive pattern with two peak values.Turbulent kinetic energy(TKE)also exhibited two peaks,one above the vegetation bending height and another at the sheath section,with a decreasing trend towards the ice cover.Furthermore,quadrant analysis showed that when the flow surface is covered by an ice cover,the contributions of inward and outward events increased compared with those observed in an open channel flow.In most cases,these contributions surpassed the sweep and ejection events.The findings enhance our understanding of vegetation’s response to diverse surface conditions and have practical implications for river management and environmental engineering.

关键词： Ice cover vegetation flow structure Reynolds shear stress turbulent kinetic energy(TKE) quadrant analysis

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Roles of fibroblast growth factors in the treatment of diabetes

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World Journal of Diabetes 2024年第3期15卷 392-402页

作者： Chun-Ye Zhang Ming Yang Bond Life Sciences Center University of MissouriColumbiaMO 65211United States Department of Surgery University of MissouriColumbiaMO 65212United States NextGen Precision Health Institution University of MissouriColumbiaMO 65212United States

Diabetes affects about 422 million people worldwide,causing 1.5 million deaths each year.However,the incidence of diabetes is increasing,including several types of diabetes.Type 1 diabetes(5%-10%of diabetic cases)and type 2 diabetes(90%-95%of diabetic cases)are the main types of diabetes in the clinic.Accumulating evidence shows that the fibroblast growth factor(FGF)family plays important roles in many metabolic disorders,including type 1 and type 2 diabetes.FGF consists of 23 family members(FGF-1-23)in humans.Here,we review current findings of FGFs in the treatment of diabetes and management of diabetic complications.Some FGFs(e.g.,FGF-15,FGF-19,and FGF-21)have been broadly investigated in preclinical studies for the diagnosis and treatment of diabetes,and their therapeutic roles in diabetes are currently under investigation in clinical trials.Overall,the roles of FGFs in diabetes and diabetic complications are involved in numerous processes.First,FGF intervention can prevent high-fat diet-induced obesity and insulin resistance and reduce the levels of fasting blood glucose and triglycerides by regulating lipolysis in adipose tissues and hepatic glucose production.Second,modulation of FGF expression can inhibit renal and cardiac fibrosis by regulating the expression of extracellular matrix components,promote diabetic wound healing process and bone repair,and inhibit cancer cell proliferation and migration.Finally,FGFs can regulate the activation of glucoseexcited neurons and the expression of thermogenic genes.

关键词： Fibroblast growth factors Type 1 diabetes Type 2 diabetes Metabolic disorders Treatment Clinical trials

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Anti-oxidative stress treatment and current clinical trials

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World Journal of Hepatology 2024年第2期16卷 294-299页

作者： Chun-Ye Zhang Ming Yang Bond Life Sciences Center University of MissouriColumbiaMO 65211United States Department of Surgery University of MissouriColumbiaMO 65212United States

Oxidative stress disturbs the balance between the production of reactive oxygen species(ROS)and the detoxification biological process.It plays an important role in the development and progression of many chronic diseases.Upon exposure to oxidative stress or the inducers of ROS,the cellular nucleus undergoes some biological processes via different signaling pathways,such as stress adaption through the forkhead box O signaling pathway,inflammatory response through the IκB kinase/nuclear factor-κB signaling pathway,hypoxic response via the hypoxia-inducible factor/prolyl hydroxylase domain proteins pathway,DNA repair or apoptosis through the p53 signaling pathway,and antioxidant response through the Kelch-like ECH-associated protein 1/nuclear factor E2-related factor 2 signaling pathway.These processes are involved in many diseases.Therefore,oxidative stress has gained more attraction as a targeting process for disease treatment.Meanwhile,anti-oxidative stress agents have been widely explored in pre-clinical trials.However,only limited clinical trials are performed to evaluate the efficacy of anti-oxidative stress agents or antioxidants in diseases.In this letter,we further discuss the current clinical trials related to anti-oxidative stress treatment in different diseases.More pre-clinical studies and clinical trials are expected to use anti-oxidative stress strategies as disease treatment or dietary supplementation to improve disease treatment outcomes.

关键词： Anti-oxidative stress treatment Clinical trials Drugs Dietary invention Reactive oxygen species

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Influence of indoor airflow on airborne disease transmission in a classroom

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Building Simulation 2024年第3期17卷 355-370页

作者： Mojtaba Zabihi Ri Li Joshua Brinkerhoff School of Engineering Faculty of Applied ScienceUniversity of British ColumbiaKelownaCanada

It has been widely accepted that the most effective way to mitigate airborne disease transmission in an indoor space is to increase the ventilation airflow,measured in air change per hour(ACH).However,increasing ACH did not effectively prevent the spread of COVID-19.To better understand the role of ACH and airflow large-scale patterns,a comprehensive fully transient computational fluid dynamics(CFD)simulation of two-phase flows based on a discrete phase model(DPM)was performed in a university classroom setting with people present.The investigations encompass various particle sizes,ventilation layouts,and flow rates.The findings demonstrated that the particle size threshold at which particles are deemed airborne is highly influenced by the background flow strength and large-scale flow pattern,ranging from 5µm to 10µm in the cases investigated.The effects of occupants are significant and must be precisely accounted for in respiratory particle transport studies.An enhanced ventilation design(UFAD-CDR)for university classrooms is introduced that places a premium on mitigating airborne disease spread.Compared to the baseline design at the same ACH,this design successfully reduced the maximum number density of respiratory particles by up to 85%.A novel airflow-related parameter,Horizontality,is introduced to quantify and connect the large-scale airflow pattern with indoor aerosol transport.This underscores that ACH alone cannot ensure or regulate air quality.In addition to the necessary ACH for air exchange,minimizing horizontal bulk motion is essential for reducing aerosol transmissibility within the room.

关键词： aerosol transmission airflow pattern horizontality COVID-19 simulation classroom ventilation

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Small molecule conjugates with selective estrogen receptor β agonism promote anti-aging benefits in metabolism and skin recovery

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Acta Pharmaceutica Sinica B 2024年第5期14卷 2137-2152页

作者： Tarik Zahr Vijay K.Boda Jian Ge Lexiang Yu Zhongzhi Wu Jianwen Que Wei Li Li Qiang Naomi Berrie Diabetes Center Columbia UniversityNew YorkNY 10032USA Department of Molecular Pharmacology and Therapeutics Columbia UniversityNew YorkNY 10032USA Department of Pharmaceutical Sciences College of PharmacyUniversity of Tennessee Health Science CenterMemphisTN 38163USA Drug Discovery Center College of PharmacyUniversity of Tennessee Health Science CenterMemphisTN 38163USA Division of Digestive and Liver Diseases Columbia UniversityNew YorkNY 10032USA Center for Human Development Columbia UniversityNew YorkNY 10027USA Department of Pathology and Cell Biology Columbia UniversityNew YorkNY 10032USA Department of Medicine Columbia UniversityNew YorkNY 10032USA

Estrogen is imperative to mammalian reproductivity,metabolism,and aging.However,the hormone activating estrogen receptor(ERs)αcan cause major safety concerns due to the enrichment of ERαin female tissues and certain malignancies.In contrast,ERβis more broadly expressed in metabolic tissues and the skin.Thus,it is desirable to generate selective ERβagonist conjugates for maximizing the therapeutic effects of ERs while minimizing the risks of ERαactivation.Here,we report the design and production of small molecule conjugates containing selective non-steroid ERβagonists Gtx878 or genistein.Treatment of aged mice with our synthesized conjugates improved aging-associated declines in insulin sensitivity,visceral adipose integrity,skeletal muscle function,and skin health,with validation in vitro.We further uncovered the benefits of ERβconjugates in the skin using two inducible skin injury mouse models,showing increased skin basal cell proliferation,epidermal thickness,and wound healing.Therefore,our ERβ-selective agonist conjugates offer novel therapeutic potential to improve aging-associated conditions and aid in rejuvenating skin health.

关键词： Estrogen receptorβ Aging Metabolism Skin injury Muscle metabolism Small molecule conjugates Regeneration Adiposity

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Monogenic features of urolithiasis: A comprehensive review

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Asian Journal of Urology 2024年第2期11卷 169-179页

作者： Kyo Chul Koo Abdulghafour Halawani Victor K.F.Wong Dirk Lange Ben H.Chew Department of Urology Yonsei University College of MedicineSeoulRepublic of Korea Department of Urology King Abdulaziz UniversityJeddahSaudi Arabia Department of Urological Sciences University of British ColumbiaStone Centre at Vancouver General HospitalVancouverBritish ColumbiaCanada

Objective: Urolithiasis formation has been attributed to environmental and dietary factors. However, evidence is accumulating that genetic background can contribute to urolithiasis formation. Advancements in the identification of monogenic causes using high-throughput sequencing technologies have shown that urolithiasis has a strong heritable component.Methods: This review describes monogenic factors implicated in a genetic predisposition to urolithiasis. Peer-reviewed journals were evaluated by a PubMed search until July 2023 to summarize disorders associated with monogenic traits, and discuss clinical implications of identification of patients genetically susceptible to urolithiasis formation.Results: Given that more than 80% of urolithiases cases are associated with calcium accumulation, studies have focused mainly on monogenetic contributors to hypercalciuric urolithiases, leading to the identification of receptors, channels, and transporters involved in the regulation of calcium renal tubular reabsorption. Nevertheless, available candidate genes and linkage methods have a low resolution for evaluation of the effects of genetic components versus those of environmental, dietary, and hormonal factors, and genotypes remain undetermined in the majority of urolithiasis formers.Conclusion: The pathophysiology underlying urolithiasis formation is complex and multifactorial, but evidence strongly suggests the existence of numerous monogenic causes of urolithiasis in humans.

关键词： Gene Genetic expression Inheritance pattern Urolithiasis

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Direct Pointwise Comparison of FE Predictions to StereoDIC Measurements:Developments and Validation Using Double Edge-Notched Tensile Specimen

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1263-1298页

作者： Troy Myers Michael A.Sutton Hubert Schreier Alistair Tofts Sreehari Rajan Kattil Department of Mechanical Engineering University of South CarolinaColumbiaSC29208USA Correlated Solutions Incorporated 121 Dutchman BlvdColumbiaSC29063USA

To compare finite element analysis(FEA)predictions and stereovision digital image correlation(StereoDIC)strain measurements at the same spatial positions throughout a region of interest,a field comparison procedure is developed.The procedure includes(a)conversion of the finite element data into a triangular mesh,(b)selection of a common coordinate system,(c)determination of the rigid body transformation to place both measurements and FEA data in the same system and(d)interpolation of the FEA nodal information to the same spatial locations as the StereoDIC measurements using barycentric coordinates.For an aluminum Al-6061 double edge notched tensile specimen,FEA results are obtained using both the von Mises isotropic yield criterion and Hill’s quadratic anisotropic yield criterion,with the unknown Hill model parameters determined using full-field specimen strain measurements for the nominally plane stress specimen.Using Hill’s quadratic anisotropic yield criterion,the point-by-point comparison of experimentally based full-field strains and stresses to finite element predictions are shown to be in excellent agreement,confirming the effectiveness of the field comparison process.

关键词： StereoDIC spatial co-registration data transformation finite element simulations point-wise comparison of measurements and FEA predictions double edge notch specimen model validation

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