Silicon photonic-based refractive index sensors are of great value in the detection of gases, biological and chemical substances. Among them, microring resonators are the most promising due to their ...compact size and narrow Lorentzian-shaped spectrum. The electric field in a subwavelength grating waveguide (SWG) is essentially confined in the low-refractive index dielectric, favoring enhanced analyte-photon interactions, which represents higher sensitivity. However, it is very challenging to further significantly improve the sensitivity of SWG ring resonator refractive index sensors. Here, a hybrid waveguide blocks double slot subwavelength grating microring resonator (HDSSWG-MRR) refractive index sensor operating in a water refractive index environment is proposed. By designing a new waveguide structure, a sensitivity of up to 1005 nm/RIU has been achieved, which is 182 nm/RIU higher than the currently highest sensitivity silicon photonic micro ring refractive index sensor. Meanwhile, utilizing a unique waveguide structure, a Q of 22,429 was achieved and a low limit of detection of 6.86 × 10
RIU was calculated.
Lower urinary tract symptoms (LUTS) are associated with frailty phenotype, a risk factor for functional decline. Our objective was to determine the association between baseline LUTS and 2-year risk ...of new functional limitation among older men.
We analyzed data from the Osteoporotic Fractures in Men (MrOS) study with baseline at Year 7 and follow-up through Year 9. Participants included 2716 community-dwelling men age ≥ 71 years without any baseline self-reported functional limitation. LUTS severity (American Urologic Association Symptom Index) was classified as none/mild (score 0-7), moderate (8-19), and severe (20-35). At baseline and follow-up, men reported their ability to complete several mobility, activities of daily living (ADLs), and cognition-dependent tasks. Risk was estimated for 3 incident functional limitation outcomes: (1) mobility (any difficulty walking 2-3 blocks or climbing 10 steps), (2) ADL (any difficulty bathing, showering, or transferring), and (3) cognition-dependent (any difficulty managing money or medications). We used Poisson regression with a robust variance estimator to model adjusted risk ratios (ARR) and 95% CIs controlling for age, site, and comorbidities; other demographic/lifestyle factors did not meet criteria for inclusion.
Overall, the 2-year risk was 15% for mobility, 10% for ADLs, and 4% for cognition-dependent task limitations. Compared to none/mild LUTS, risk of incident mobility limitations was increased for moderate (ARR = 1.35, 95% CI: 1.12, 1.63) and severe LUTS (ARR = 1.98, 95% CI: 1.48, 2.64). Men were also at higher risk for incident ADL limitations if they reported moderate (ARR = 1.32, 95% CI: 1.05, 1.67) and severe LUTS (ARR = 1.62, 95% CI: 1.07,2.43). Results were somewhat attenuated after adjusting for the frailty phenotype but remained statistically significant. LUTS were not associated with incident cognition-dependent task limitations.
LUTS severity is associated with incident mobility and ADL limitations among older men. Increased clinical attention to risk of functional limitations among older men with LUTS is likely warranted.
Background South Asian individuals have increased cardiovascular disease and mortality risks. Reliance on creatinine- rather than cystatin C-based estimated glomerular filtration rate (eGFRcys) may ...underestimate the cardiovascular disease risk associated with chronic kidney disease. Methods and Results Among 7738 South Asian UK BioBank participants without prevalent heart failure (HF) or atherosclerotic cardiovascular disease, we investigated associations of 4 eGFRcys and creatinine-based estimated glomerular filtration rate categories (<45, 45-59, 60-89, and ≥90 mL/min per 1.73 m
) with risks of all-cause mortality, incident HF, and incident atherosclerotic cardiovascular disease. The mean age was 53±8 years; 4085 (53%) were women. Compared with creatinine, cystatin C identified triple the number of participants with estimated glomerular filtration <45 (n=35 versus n=113) and 6 times the number with estimated glomerular filtration 45 to 59 (n=80 versus n=481). After multivariable adjustment, the eGFRcys 45 to 59 category was associated with higher risks of mortality (hazard ratio HR, 2.38 95% CI, 1.55-3.65) and incident HF (sub-HR sHR, 1.87 95% CI, 1.09-3.22) versus the eGFRcys ≥90 category; the creatinine-based estimated glomerular filtration rate 45 to 59 category had no significant associations with outcomes. Of the 7623 participants with creatinine-based estimated glomerular filtration rate ≥60, 498 (6.5%) were reclassified into eGFRcys <60 categories. Participants who were reclassified as having eGFRcys <45 had higher risks of mortality (HR, 4.88 95% CI, 2.56-9.31), incident HF (sHR, 4.96 95% CI, 2.21-11.16), and incident atherosclerotic cardiovascular disease (sHR, 2.29 95% CI, 1.14-4.61) versus those with eGFRcys ≥90; those reclassified as having eGFRcys 45 to 59 had double the mortality risk (HR, 2.25 95% CI, 1.45-3.51). Conclusions Among South Asian individuals, cystatin C identified a high-risk chronic kidney disease population that was not detected by creatinine and enhanced estimated glomerular filtration rate-based risk stratification for mortality, incident HF, and incident atherosclerotic cardiovascular disease.
Large differences between estimated glomerular filtration rate (eGFR) based on cystatin C (eGFRcys) and creatinine (eGFRcr) occur commonly. A comprehensive evaluation of factors that contribute to ...these differences is needed to guide the interpretation of discrepant eGFR values.
Cohort study.
468,969 participants in the UK Biobank.
Candidate sociodemographic, lifestyle factors, comorbidities, medication usage, and physical and laboratory predictors.
eGFRdiff, defined as eGFRcys minus eGFRcr, categorized into 3 levels: lower eGFRcys (eGFRdiff, less than−15mL/min/1.73m2), concordant eGFRcys and eGFRcr (eGFRdiff, −15 to<15mL/min/1.73m2), and lower eGFRcr (eGFRdiff, ≥15mL/min/1.73m2).
Multinomial logistic regression models were constructed to identify predictors of lower eGFRcys or lower eGFRcr. We developed 2 prediction models comprising 375,175 participants: (1) a clinical model using clinically available variables and (2) an enriched model additionally including lifestyle variables. The models were internally validated in an additional 93,794 participants.
Mean±standard deviation of eGFRcys was 88±16mL/min/1.73m2, and eGFRcr was 95±13mL/min/1.73m2; 25% and 5% of participants were in the lower eGFRcys and lower eGFRcr groups, respectively. In the multivariable enriched model, strong predictors of lower eGFRcys were older age, male sex, South Asian ethnicity, current smoker (vs never smoker), history of thyroid dysfunction, chronic inflammatory disease, steroid use, higher waist circumference and body fat, and urinary albumin-creatinine ratio>300mg/g. Odds ratio estimates for these predictors were largely inverse of those in the lower eGFRcr group. The model’s area under the curve was 0.75 in the validation set, with good calibration (1.00).
Limited generalizability.
This study highlights the multitude of demographic, lifestyle, and health characteristics that are associated with large eGFRdiff. The clinical model may identify individuals who are likely to have discrepant eGFR values and thus should be prioritized for cystatin C testing.
Estimated glomerular filtration rate (eGFR) based on cystatin C and creatinine may differ substantially within an individual. Although most clinicians are aware that creatinine is influenced by muscle mass, there are additional numerous lifestyle and health characteristics that may affect serum concentrations of either biomarker. Our analyses of 468,969 individuals in the UK Biobank identified independent predictors of large differences between eGFR based on cystatin C and eGFR based on creatinine, which may inform the interpretation of discrepant eGFR values within an individual. We developed models that may be implemented at a population level to help health systems identify individuals who are likely to have large differences between eGFR based on cystatin C and eGFR based on creatinine and thus should be prioritized for cystatin C testing.
•The damage of stud has a greater influence on fatigue performances compared to static properties.•Compared with the stud damage, the concrete crack has less influence on the fatigue performance.•The ...existing calculation methods of residual slip are not completely applicable to the test results.
As a key component in composite beams, the studs are prone to fatigue failure under reciprocating load. Fatigue problem is more prominent especially under circumstances of concrete cracking, stud corrosion or with initial damage. Therefore, static and fatigue tests are carried out to study the fatigue properties of push-out specimens with initial defects, including stud damage and concrete cracking. The test results show that the damage of stud has a great influence on fatigue life, while the crack of concrete has a little influence on fatigue life. The damage of stud has a greater influence on fatigue performances compared to static properties. In addition, based on the dissipative energy theory and experimental phenomenon, the roles of stud and concrete in the process of stud fatigue failure and their interaction are summarized. The dissipative energy mainly includes the shear plastic strain energy of the stud, the plastic strain energy of concrete under compression after the stud, and the heat energy generated by the friction between the stud and concrete.
•A three-dimensional nonlinear finite element model was established and validated by the experimental results of the push-out tests.•The parametric analyses were conducted to discuss the influences ...of the stud diameter, concrete strength, stud aspect ratio and cover thickness on the shear behavior for stud-UHPC connections.•An algebraic model characterized by elastic, elasto-plastic and plastic stages is proposed to predict the load-slip relationships, which agrees well with the experimental curves.
This paper focuses on prediction of longitudinal shear behaviour including load-slip relationships of stud connections between UHPC (ultra-high performance concrete) slabs and steel beams. An experimentally validated finite element (FE) model is used for parametric studies to understand the influences of stud diameter, concrete strength, stud aspect ratio and cover thickness on the shear behaviour. This study shows that the shear strength increases as parabolic and linear functions of the stud diameter and concrete strength, respectively, especially for large diameter studs embedded in higher strength concretes. Smaller stud aspect ratios and cover thicknesses are important to ensure stud fracture, thereby leading to an optimal UHPC slab thickness. Moreoever, an algebraic calculation model characterized by elastic, elasto-plastic and plastic stages is proposed, in which the key parameters, including the yielding slip of concrete, the effective plastic length in the concrete and the slip at onset of stud yielding are defined based on the FE results. This algebraic model’s predictions are successfully compared with the experimental curves from different published studies.
•The curing method had a negligible effect on the fatigue performance of the prefabricated CA-UHPC decks.•The fatigue performance of prefabricated CA-UHPC decks subjected to negative bending moment ...is extremely superior.•Joints will crack at low stress levels and when S/Smax was smaller than 0.438, the fatigue performance only under fatigue loading could be guaranteed.
The concrete deck of a steel–concrete composite bridge is vulnerable to cracking under negative bending moments of fatigue loads. Thus, this work performed fatigue tests on the prefabricated decks to study the influences of the curing method and stress level on the fatigue behavior of the prefabricated ultrahigh-performance concrete (UHPC) deck in an assembled steel–UHPC composite beam under negative bending moments. A numerical simulation was further conducted to investigate the behavior of the decks with joints. The results indicate that the effect of the curing method on the fatigue performance of reinforced UHPC decks is not as pronounced as that on their static performance. The prefabricated UHPC decks exhibit excellent fatigue performance, and fatigue cracks do not form until 13 million loading cycles when the upper fatigue limit is near the breaking load. On the other hand, the deck with a joint has a substantially lower fatigue cracking resistance than the prefabricated ones. The maximum fatigue crack width of the deck with a joint is 0.08 mm at low stress amplitudes. As a result, even though the UHPC has high fatigue performance, further joint reinforcing is recommended.
•Large-diameter (30 mm) high-strength friction grip through-bolts were proposed to connect the prefabricated thin UHPC slab (55 and 35 mm thick）and steel girder to reduce the self-weight of composite ...bridges and improve the constructional efficiency.•Thirty push-out tests were carried out to observe the influences of bolt diameter, slab thickness, bolt strength, pretension force and random asymmetric clearance of the bolt within the slab and joist on the shear strength and stiffness.•Regression analysis of these experimental data was conducted to study the shear behaviour of such connections.•A plastic-hinging based mechanical model was proposed to predict the shear resistance of such connections.
In order to improve the construction efficiency and reduce the self-weight of composite bridges, prefabricated thin UHPC (ultra-high performance concrete) decks can be connected to steel girders by high-strength, large-diameter friction grip through-bolts. This paper presents a pilot experimental study into the shear performances of such composite connections. Thirty push-out tests were carried out to observe the influences of bolt diameter, slab thickness, bolt strength, pretension force and random asymmetric clearance of the bolt within the slab and joist. The observed failure modes include bolt fracture, pronounced permanent flexure of the bolts due to extensive yield, and crushing/splitting of the UHPC. 36% and 25% increases in diameter (from 22 to 30 mm) and tensile resistance (from 795 to 995 MPa) in 55 mm thick slabs led to 43% and 11% improvement respectively in connection shear resistance. Moreover, a bolt pretension force increase from 150 to 200 kN and a slab decrease in thickness from 55 to 35 mm respectively changed the failure mode from bolt bending to bolt fracture and reduced the shear resistance by 15%. Random asymmetric clearances of the bolts between 0.17 and 5.43 mm led to 88%-100% reduction of connection stiffness at the first slip stage and decreased shear resistance by up to 11%. Regression analysis shows that connection shear strength, stiffness and ductility are mixed polynomial and exponential functions of the key connection variables.
•A two-layered FGUHPC member was designed to meet the bearing and fire-resistant requirements under high temperature.•All specimens exhibited good integrality and fire-resistant behaviors despite of ...microcracks.•Cast-in bolts could improve bond strength under room temperature whereas the effect was insignificant as temperature rose.
This paper designed a two-layered functionally graded ultra-high performance concrete (FGUHPC) member to meet the bearing and fire-resistant requirements subjected to elevated temperature, where the UHPC layer was used to bear loads and was protected by the lightweight aggregate concrete (LWAC) layer from high temperature. Debonding tests were conducted to evaluate its interfacial behaviors under ambient and high temperatures and the effect of cast-in bolts were investigated. The results showed that all specimens exhibited good fire-resistant behaviors, no visible cracks and spalling were observed for the UHPC layers while the LWAC layers maintained good integrality. Embedded bolts could significantly improve the initial stiffness, bond strength and post-peak ductility of specimens under direct tension at room temperature. The enhancement of bond strength was 40.0 % and 56.5 % when employing bolts with a diameter of 10 mm and 12 mm while that of ultimate displacement was 62.2 % and 58.1 % respectively compared with the specimens without bolts. In the case of high temperature, all specimens showed brittle failure, the bond strength obviously decreased and the effect of bolts on bond behaviors was insignificant due to the deterioration of the LWAC layers. All specimens without bolts showed debonding failure during the tests while the failure mode was converted from breakout to splitting or pullout for the specimens with bolts as the temperature increased.
•The joint using UHPC with coarse aggregates may ensure the fatigue performance.•SWM treatment is beneficial to fatigue performance of bridge deck with wet joint.•The joint can reduce the effect of ...overload on fatigue performance of bridge deck.
The Fifth Nanjing Yangtze River Bridge had adopted accelerated bridge construction utilizing precast systems to connect the prefabricated plate with the cast-in-place ultra-high performance concrete (UHPC) wet joint. Wet joints are prone to crack under fatigue load. In this study, the steel wire mesh (SWM) treatment method was adopted to enhance the interface crack resistance, and add coarse aggregate (CA) to UHPC to reduce cost. Decks were tested under static and fatigue loadings to study the effects of CA, SWM interface treatment, and stress level on fatigue performance. Results indicate that the fatigue performance of wet joints using UHPC with CA was similar to that using regular UHPC. Dovetail wet joints using SWM interface treatment effectively guarantee the bridging effect of the fiber at the interface and disperse fatigue cracks. Overloading affected the fatigue performance, and the fatigue damage was linear to the upper limit of stress when the stress ratio was fixed. Secant stiffness was used to evaluate the fatigue damage of decks, and the calculated damage was in good agreement with the actual bearing capacity loss. This study verified that the innovative dovetail wet joint is practical, economical, and guarantees fatigue performance.
