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BackgroundCurrent clinical tests for mycobacterial pulmonary diseases (MPD), such as pulmonary tuberculosis (PTB) and non-tuberculous mycobacteria pulmonary diseases (NTM-PD), are inaccurate, time-consuming, sputum-dependent, and/or costly. We aimed to develop a simple, rapid and accurate breath test for screening and differential diagnosis of MPD patients in clinical settings.MethodsExhaled breath samples were collected from 142 PTB, 68 NTM-PD and 9 PTB&NTM-PD patients, 93 patients with other pulmonary diseases (OPD) and 181 healthy controls (HC), and tested using the online high-pressure photon ionisation time-of-flight mass spectrometer (HPPI-TOF-MS). Machine learning models were trained and blindly tested for the detection of MPD, PTB, NTM-PD, and the discrimination between PTB and NTM-PD, respectively. Diagnostic performance was evaluated by metrics of sensitivity, specificity, accuracy, and area under the receiver operating characteristic curve (AUC).ResultsThe breath PTB detection model achieved a sensitivity of 81.8%, a specificity of 94.3%, an accuracy of 90.7%, and an AUC of 0.957 in the blinded test set (n=150). The corresponding metrics for the NTM-PD detection model were 95.5%, 86.7%, 88.0% and 0.947, respectively. For distinguishing PTB from NTM-PD, the model also achieved good performance with sensitivity, specificity, accuracy, and AUC of 95.5%, 90.9%, 93.9% and 0.974, respectively. 24 potential breath biomarkers associated with MPD were putatively identified and discussed, which included 2-picoline, ethanol, 1-Pentene, etc.ConclusionsThe developed breathomics-based MPD detection method was demonstrated for the first time with good performance for potential screening and diagnosis of PTB and NTM-PD using a refined operating procedure on the HPPI-TOF-MS platform.

The mechanical characteristics of high-strength steel (HSS) at high temperatures vary significantly from those of mild steel, so fire design regulations derived from mild steel cannot be transferred to HSS structures. Therefore, this paper investigates the fire resistance of beams made of HSSs, which will facilitate the design and application of HSS structures. Due to the heat dissipation of the concrete floor, steel beams are generally heated from three sides, and the temperature distribution in the steel beam cross-section is nonuniform. For such cases, the fire resistance of HSS beams is assessed using finite element models (FEMs) with nonuniform temperature distribution. A Ramberg–Osgood model was used to predict stress–strain relationships of Q460, Q690, and Q960 HSSs at elevated temperatures, and the model was verified by material tests. In the FEM, the proposed stress–strain relationships of HSSs at elevated temperatures, initial geometric imperfections and residual stress are considered for better accuracy. After verifying the established model against experimental results, the influence of nonuniform temperature distribution, load pattern, steel grade, and slenderness ratio on the resistance of HSS beams is investigated by conducting parametric analyses using the verified FEM. It is found that the critical bending moment of steel beams at elevated temperatures associated with lateral-torsional buckling highly depends on the reduction of elastic modulus of steel. By comparing FEM results with EN 1993-1-2, it is evident that EN 1993-1-2 is unsuitable for assessing the fire resistance of HSS beams. Therefore, the expression specified in EN 1993-1-2 is modified by fitting the finite analysis results to more accurately evaluate the fire resistance of HSS beams considering the nonuniform temperature distribution.

Using precast concrete floors can greatly improve the construction efficiency of steel structures, and the development of the connection between precast slabs affects the application of precast concrete floors in steel structures. In this paper, a new connection between the precast concrete floor and steel beam is proposed. The bending capacity of the connection was investigated through experiments, and compared with that of the cast-in-place floor. The test results showed that the reliability of the new connection was excellent, and the bending capacity of the floor with this connection is basically the same as that of the cast-in-place floor. The finite element software ABAQUS was employed to simulate the bending behavior of the new connection floor and cast-in-place floor, and the feasibility of the model was verified by comparing it with the experimental results. The model was used to analyze the structural response of the two types of composite beams composed of new connections and precast floor, cast-in-place floor, and steel beam, respectively. The load-bearing capacity and failure modes of the two composite beams were compared. The results showed that the bearing capacity of the composite beam fabricated with the new connection can reach that of the cast-in-place floor composite beam. This is only a preliminary investigation about the new connection and there are some limitations as well.

Steel tube confined reinforced concrete (STCRC) column is a new type of composite compressive member. In recent years, the structural performance of the STCRC columns has been widely studied to promote its application, and this paper presents experimental and numerical studies on the fire-resistance behaviour of the middle-length members. Parameters, including thickness of steel tube, loading mode (axial or eccentric), and load ratio, were considered in the tests. Moreover, the furnace temperature, column temperature, axial displacement, lateral displacement, and applied load were recorded during the tests, and the failure pattern was obtained after the tests. The finite element model (FEM) was developed by ABAQUS and validated against the test results. Through parametric analyses, the effects from eccentric ratio, load ratio, cross-section diameter, material strength, the thickness of steel tube, and reinforcement ratio on the fire resistance of the middle-length STCRC columns were further studied. It was found that increasing the section diameter, concrete strength, yield strength of reinforcement, and reinforcement ratio would enhance the fire resistance of the columns. However, increasing eccentricity, yield strength of steel tube, thickness of steel tube, and load ratio would reduce the fire resistance of the columns.

In recent years, high-strength steel (HSS) is finding increasing applications in building construction due to its excellent strength and durability properties. However, structures, incorporating HSS, exhibit lower fire resistance due to rapid deterioration of their mechanical properties at elevated temperatures. For evaluating the fire resistance of steel structures, high-temperature properties of steel are to be specified as input data. The properties of steel not only vary with temperature but also the extent of variation is influenced by the type and grade of steel. This paper presents a state-of-the-art review on temperature-dependent properties of HSS. The available data and relations for thermal, mechanical, and deformation properties of HSS are compiled. Using these data, the variations in the elevated properties of HSS are established and the reasoning for such variation is explained. Finally, the critical properties to be considered for evaluating the fire resistance of structures, incorporating HSS, are discussed.

In this paper, we study the Fraunhofer diffraction pattern in a four-level quantum dot nanostructure. The quantum dot interacts with two weak probe and signal laser fields and two strong coupling lights where one of them is a two-dimensional standing wave field. We study the Fraunhofer diffraction pattern of the transmitted probe light when the coherent driving light becomes plan wave or Laguerre Gaussian (LG) vortex light. We found that by controlling the relative phase of the applied lights and orbital angular momentum (OAM) of LG light, the Fraunhofer diffraction pattern can be controlled and the probe energy transfer from zero order to the higher orders, respectively. Moreover, we realized that by controlling the OAM number of the vortex light the asymmetric diffraction pattern is possible.

To deeply understand and even describe the evolutions of the low-energy twin boundary density (BLD∑3n) in a thermal-plastic deformation process, an improved twin density model as a function of average grain size and stored energy is developed. For Nimonic 80A superalloy, the model is solved based on the EBSD statistical results of grain size and BLD∑3n in the specimens compressed at temperatures of 1273–1423 K and strain rates of 0.001–10 s–1. The corresponding relationships of BLD∑3n with stored energy and grain size varying with temperature and strain rate are clarified by the superimposed contour plot maps. It is summarized that BLD∑3n increases with increasing stored energy and decreasing grain size, and higher BLD∑3n with finer grains corresponds with lower temperatures and higher strain rates. Such relationships are described by the improved twin density model, and the prediction tolerance of the solved model is limited in 2.8%.

Most of the previous studies on restrained steel beam behaviour in fire conditions have neglected the creep effect due to the lack of applicable creep models. A finite element model (FEM) is determined in this study to investigate fire resistance and the behaviour of restrained high-strength (RHS) Q690 steel beams in fire considering the high-temperature Fields & Fields creep model. A comparison of the results obtained by the FEM with those from previous tests proved the validity of the FEM. A second FEM without a creep model is also established to study the influence of creep on the fire resistance of restrained steel beams. Results showed that creep has a serious effect on the behaviour of restrained steel beams in fire. Thus, ignoring creep will possibly lead to unsafe designs. Several parametric studies are carried out using the validated FEM with the aim to investigate the influencing factors on the fire response of RHS Q690 steel beams. Analysis shows that some of the investigated factors, such as heating rate, cross-section temperature distribution, rotational restraint stiffness and span-to-depth ratio, have been found crucial in the fire resistance of RHS Q690 steel beams. Furthermore, a simplified approach is presented for RHS Q690 steel beams based on the results of the FEM, including the creep effect, to calculate the moment capacity. This approach is also suitable for calculating the critical temperature of RHS Q690 steel beams.

In order to deeply understand the grain growth behaviors of Ni80A superalloy, a series of grain growth experiments were conducted at holding temperatures ranging from 1223 to 1423 K and holding time ranging from 0 to 3600 s. A back-propagation artificial neural network (BP-ANN) model and a Sellars model were solved based on the experimental data. The prediction and generalization capabilities of these two models were evaluated and compared on the basis of four statistical indicators. The results show that the solved BP-ANN model has better performance as it has higher correlation coefficient (r), lower average absolute relative error (AARE), lower absolute values of mean value (μ) and standard deviation (ω). Eventually, a response surface of average grain size to holding temperature and holding time is constructed based on the data expanded by the solved BP-ANN model, and the grain growth behaviors are described.

Post-earthquake fires occur after earthquakes and have commonly been encountered throughout history. The fires are particularly deadly and threaten the stability of buildings as possible structural damages caused by seismic loading can be exacerbated by temperature loading. Moreover, damage to insulation during seismic events causes accelerated heating in portions of members experiencing large bending moments. A method is proposed for evaluating the stability and deflection of a semi-braced structural steel frame subjected to post-earthquake fire conditions. The proposed method adopts the interstorey drift concept and assumes that each member in the frame has three segments of differing temperatures, modelling the damage to insulation near moment connections and/or midspans of flexural members. The method is presented in the form of a deflection equation, which indicates the instability of the frame when the lateral stiffness in the denominator reaches zero. The proposed method is demonstrated via a numerical example, and the duration of fire until the given frame becomes unstable is computed, with the results validated via finite element analysis. The degrees of structural and insulation damage are also varied in parametric analyses, showing that the lateral stiffness and critical temperatures of a frame subjected to post-earthquake conditions can be severely reduced.

In the present study, a novel single domain antibody (sdAb) fusion protein, named everestmab, composing of a mutated GLP-1(A8G) fused to the tandem bispecific humanized GLP-1R-targeting and albumin-binding nanobodies was designed and characterized for the therapies for type 2 diabetes mellitus (T2DM). Surface plasmon resonance (SPR) measurements demonstrated everestmab associates with serum albumins of rat and monkey species with high affinity, and tends to be cross-reactive with rat and monkey species.

The current cold-formed steel (CFS) wall is limited to the low-rise cold-formed thin-walled steel structure, which is inappropriate for multi-story constructions due to its low shear resistance and poor corrosion resistance of outer sheathing board. Therefore, a new composite wall of CFS frame sheathing with concrete and plasterboard was proposed, the cast-in situ concrete layer was used for the outer surface in response to the needs of corrosion resistance, and the plasterboard was utilized for the inner surface to reduce weight. This paper presented a quasi-static test on the seismic behavior of one CFS wall and three composite-walls’ sheathings with concrete and plasterboard to obtain different failure modes and investigate the influence of different sheathing and opening sizes. Combined with the finite element model, a large parametric study of composite walls was conducted to analyze the impact of load ratio, reinforcement ratio, sheathing board, and concrete and steel strength. Test and finite element analysis (FEA) results demonstrate that the seismic performance of composite walls with concrete and plasterboard is satisfactory considering their shear strength, ductility, and energy dissipation. Load ratio, opening size, and reinforcement ratio significantly affect the seismic performance of the composite wall, while the concrete and steel strength and sheathing board have minimal effects. The seismic design suggestions of composite walls are given based on this study.

Due to its high load-bearing capacity, high-strength steel is progressively more used in present engineering applications. However, the current design codes methodology for the lateral-torsional buckling (LTB) ultimate capacity of laterally unrestrained steel beams is based on experiments limited to room temperature and mild steel. A numerical analysis of steel beams’ ultimate bearing capacity in bending was carried out to evaluate the lateral-torsional bending of different high-strength steels, namely, Q460, Q690, and Q960 steel at high temperatures. As a comparison, the lateral-torsional bending of Q235 steel beam was also studied. Finite element models (FEMs) were generated using Abaqus with taking into account initial geometrical imperfection and residual stress. The validation of the FEMs has been established by comparing the ultimate flexural resistances obtained from previous tests with those from FEM. A number of parametric studies were taken to investigate the effects of different factors such as various span lengths, residual stress, steel grades, temperatures, and cross-section size on the flexural-torsional buckling (FTB) behavior of laterally unrestrained steel beams. Furthermore, the overall bending capacity of laterally unrestrained steel beams has been shown to be deteriorating at high temperatures. In addition, based on findings from the FEMs, design curves were proposed for evaluating the FTB of high-strength steel beams at elevated temperatures. The results were compared with the design curves given by design codes of GB 51249-2017 and EN 1993-1-2.

To better understand the mechanical behavior of cold-formed steel (CFS) quadruple-limb built-up box-section (QBB) columns associated with flexural buckling, 12 axial compression tests with ...

In mammals, dormant primordial follicles represent the ovarian reserve throughout reproductive life. In vitro activation of dormant primordial follicles has been used to treat patients with premature ovarian insufficiency (POI). However, there remains a lack of effective strategies to stimulate follicle activation in vivo. In this study, we used an in vitro ovarian culture system and intraperitoneal injection to study the effect of lithium treatment on primordial follicle activation. Lithium increased the number of growing follicles in cultured mouse ovaries and promoted pre-granulosa cell proliferation. Furthermore, lithium significantly increased the levels of phosphorylated protein kinase B (Akt) and the number of oocytes with forkhead Box O3a (FOXO3a) nuclear export. Inhibition of the phosphatidylinositol 3 kinase (PI3K)/Akt pathway by LY294002 reversed lithium-promoted mouse primordial follicle activation. These results suggest that lithium promotes mouse primordial follicle activation by the PI3K/Akt signaling. Lithium also promoted primordial follicle activation and increased the levels of p-Akt in mouse ovaries in vivo and in human ovarian tissue cultured in vitro. Taken together, lithium promotes primordial follicle activation in mice and humans by the PI3K/Akt signaling. Lithium might be a potential oral drug for treating infertility in POI patients with residual dormant primordial follicles.

The objective of this paper is to to ascertain the reliable mechanical properties of cold-formed Q345 steel at elevated temperatures while considerting the effects of tensile strain rate an...

The comprehensive nonlinear flow behaviors of a ductile alloy play a significant role in the numerical analysis of its forming process. The accurate characterization of as-forged Ti−13Nb−13Zr alloy was conducted by an improved intelligent algorithm, GA−SVR, the combination of genetic algorithm (GA) and support vector regression (SVR). The GA−SVR model learns from a training dataset and then is verified by a test dataset. As for the generalization ability of the solved GA−SVR model, no matter in β phase temperature range or (α+β) phase temperature range, the correlation coefficient R-values are always larger than 0.9999, and the AARE-values are always lower than 0.18%. The solved GA−SVR model accurately tracks the highly-nonlinear flow behaviors of Ti−13Nb−13Zr alloy. The stress−strain data expanded by this model are input into finite element solver, and the computation accuracy is improved.

A series of fire tests on eight circular tubed steel reinforced concrete (CTSRC) stub columns subjected to axial loading are presented in this paper. The influences of load level and steel tube thickness on the fire resistance of the CTSRC stub columns were investigated. Two similar specimens were tested with the same test scenario to obtain more reasonable data. The temperatures in steel and concrete, axial displacement, fire resistance, and failure mode were recorded and discussed. The test results show that the load level has a great influence on the fire resistance of CTSRC stub columns. The steel tube thickness has a significant influence on the fire resistance of CTSRC stub columns when subjected to a higher load level. Thermal and structural finite element (FE) models were developed to analyze the temperature distributions and fire responses of CTSRC stub columns by employing the program ABAQUS. These developed models were validated by the test data. Extensive parametric studies were carried out by using the FE method to investigate the influences of key factors on the temperature distributions and fire resistances of CTSRC stub columns. The factors considered for thermal analysis include cross-sectional dimension, steel tube thickness, and concrete type, while the factors considered for structural analysis include load ratio, cross-sectional dimension, steel tube thickness, concrete strength, and steel strength. The parametric studies indicate that the cross-sectional dimension has a more significant influence than the steel tube thickness on the temperature magnitudes of CTSRC stub columns. The load ratio, cross-sectional dimension, and steel tube thickness have more significant influence than concrete strength on the fire resistance of CTSRC stub columns. Based on the results of the parametric studies, a simplified method to predict the steel temperatures and the compressive load bearing capacities of CTSRC stub columns exposed to fire is proposed.

When it is subjected to a fire, creep strain developed in a steel column can significantly influence the behaviour of the column. As the result, the column deformation will be increased and the strength will be decreased. However, the effect of creep in steel structures has not been fully considered in current fire resistance design codes. Presented in this paper is a study on creep buckling of Q460 steel columns subjected to elevated temperatures via experimental and numerical investigations. Six high-strength Q460 steel columns with welded H shape were tested for the determination of creep buckling strength at elevated temperatures. The effects of the slenderness ratio, load ratio, and elevated temperature on failure time corresponding to creep buckling (also called as creep buckling time) were taken into consideration in the investigations. The evolutions of furnace and column temperatures, column lateral and axial displacements associated with fire duration were measured. The creep buckling time of the columns were obtained based on the magnitudes of axial and lateral displacement of the columns subjected to constant elevated temperature and compressive load. The test results showed that the creep deformation of high strength Q460 steel columns became significant at temperature 800 °C even the applied load level was as low as 10%. The creep buckling time of Q460 steel columns are sensitive to load ratio, slenderness and temperature. Finite element analysis program ANSYS was employed to establish a structural model of Q460 steel column subjected to the constant elevated temperature and compressive load, with mechanical properties at elevated temperature, creep strains and residual stresses induced by welding being taken into account. The finite element model was validated by the test results. Parametric studies were carried out to quantitatively determine the effects of the slenderness ratio, load ratio, temperature and geometric imperfections on the creep buckling time of Q460 steel columns.

Presented in this paper are test results on mechanical properties of high strength Q690 steel after being exposed to high temperatures. Yield strength, tensile strength, elastic modulus and ratio of ultimate elongation were obtained based on tension stress-strain relationships of Q690 steel after exposure to temperature ranging from 300 to 1000 °C. Two cooling methods, namely air cooling and water cooling, were applied to cool down the heated specimens from high temperature to ambient condition. The mechanical properties comparison on different high strength steels with various thickness are carried out to investigate the effect of thickness on reduction factors of strength and elastic modulus of high strength steels after high temperature exposure. The study shows that the strength deterioration after being exposed to high temperatures is not significant for the temperature up to 600 °C, no matter which cooling method is applied. The strength reduction is approximately 25% after being exposed to temperature 700 °C. However, when the air cooling is applied, the strength decreases significantly and the ultimate elongation increases noticeably being exposed to temperature 800 °C−1000 °C but the opposite is found when water cooling is applied. The influence of elevated temperature and cooling method on the elastic modulus is negligible. The deteriorations of the material properties are different for different steels. The strength deterioration of thinner steel plate is more significant than that of thicker steel plate. Equations to predict residual factors of mechanical properties of high strength Q690 steel with 20 mm thickness were proposed to evaluate the post fire capacity of high strength Q690 steel members.

Lightweight floors built with cold-formed steel C-shape joists and oriented strand board sheathing is one of the primary floor systems in cold-formed steel residential construction. In order to investigate the flexural capacity with accounting for the composite action of the floor system, two tests on the flexural capacity of the floor system were carried out. The test results indicated that the load-carrying capacity of the floor system was significantly affected by the spacing of the screws that connect the joist and oriented strand board sheathing. The primary failure mode of the floor system was the local buckling at the critical section of the C-shape joist although there was tendency of lateral-torsion buckling of the joist. The wavelength of the buckling mode was approximately equal to the screw spacing. A finite element mode was established to simulate the structural behaviour of the floors by commercial software ANSYS and it was found that the numerical results agreed well with the test data. Parametric studies were carried out based on numerical analysis to investigate how the flexural capacity of the floors was influenced by different factors such as screw spacing, joist spacing and sheathing thickness, etc. Finally, based on the test data and numerical analysis results, a simplified design method was proposed to predict the flexural capacity of the floors with accounting for the composite action. The results obtained from the proposed method were validated by both experimental and numerical investigations of two full-scale lightweight floors built with cold-formed steel C-shape joist and oriented strand board subfloor.

This paper presents the effect of temperature and tensile-strain rate on the mechanical properties of high-strength low-alloy structural Q460 steel. Standard coupon tensile tests were carri...

When exposed to elevated temperatures, steel structures undergo increasing permanent deformations with time even when the applied stress level is below that of yield stress, and this time-dependent deformation is referred to as creep. Thus, creep can be defined as an increase in strain in a solid material under constant stress over a period. The creep strain can be calculated by a creep model. As the creep models are highly phenomenological, without a consistent description, it is difficult to evaluate and extend the application of existing creep models to different structural steels. In addition, much of the available creep data in literature are for carbon steels. Therefore, for better understanding of creep effects in new type steels, which are widely used in structural engineering applications, relevant experimental creep data and the corresponding constitutive creep models are needed. This chapter deals with the creep strain of high strength steels, including Q460 steel, Q690 steel, and A572 steel, at elevated temperatures. Creep test data and creep model and creep buckling of high strength steel columns are also presented.