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Severe building integrated photovoltaic (BIPV) fires enhance the need of precise risk assessment on photovoltaic (PV) modules. In the current study, two widely used photovoltaic (PV) panels with different coverings are tested using a cone calorimeter under a wide range of incident heat fluxes (from 18 to 70 kW/m²) to characterize the influence of window flame radiation on the burning behaviors of the samples. Several key parameters including the ignition temperature and time, heat release rate (HRR), and concentration of toxic gases are investigated. The experimental results show that glass covering instead of polyethylene terephthalate covering could effectively improve the flame-retardant and smoke-suppression properties of PV composites. In addition, exposing the two samples to high incident heat fluxes would be very dangerous for the peak HRR and fire growth rate index, and fractional effective exposure dose values rise as the incident heat flux increases from 18 to 70kW/m², while the ignition time and time to peak HRR reduce. Further, three different decomposition regions of the two composites, which are identified within the range of the applied external heat flux, represent the different roles of flame retardants and covering glass, respectively. This work provides a method for fire safety specialists to evaluate the fire hazards of PV modules, which include thermal and toxic hazards, in BIPV safety assessments. [ABSTRACT FROM AUTHOR]

Background: The underlying pathophysiology of BA distribution is unclear and intriguing. Using high-resolution magnetic resonance imaging (HR-MRI), we sought to explore the plaque distribution of low-grade basilar artery (BA) atherosclerosis and its clinical relevance.Methods: We retrospectively analyzed the imaging and clinical data of 61 patients with low-grade atherosclerotic BA stenosis (<50%). On HR-MRI, the plaques were categorized based on the involvement of the ventral, dorsal, or lateral sides of BA wall. A culprit plaque was defined if it was on the same slice or neighboring slices of symptomatic pontine infarcts and played a probable causal role (dorsal plaques with median pontine infarcts or lateral plaques with ipsilateral pontine infarcts). The relationships between plaque distribution and clinical presentations were analyzed.Results: Twenty-five symptomatic and thirty-six asymptomatic BAs with 752 HR-MRI image slices were studied. The average length of BA atherosclerosis plaques was 12.16 ± 5.61mm (10.30 ± 6.44mm in symptomatic and 13.46 ± 7.03mm in asymptomatic patients, p = 0.079). The plaque distribution was similar at ventral (29.0%), dorsal (37.6%) and lateral walls (33.1%). The BA plaques in symptomatic patients were more frequently located at the dorsal (42.5%) and lateral (41.2%) walls than at the ventral walls (16.1%; P < 0.05). Compared with symptomatic patients, asymptomatic patients more likely had their plaques distributed at the ventral walls (P = 0.022). Culprit plaques were observed in 85.0% (17/20) pontine infarcts in symptomatic patients and only 14.3% (2/14) silent pontine infarcts in asymptomatic patients (p < 0.001).Conclusions: Low-grade BA atherosclerosis has a long distribution and evenly involves ventral, dorsal and lateral walls. The plaques at dorsal and lateral walls are associated with symptomatic pontine infarcts but not with silent infarcts. [ABSTRACT FROM AUTHOR]

A new methylene-bridged dimeric flavonol glycoside, methylenebisnicotiflorin (1), was isolated from ripe Pu-er tea, along with 10 known flavonoids (2–11) and seven known phenolic compounds (12–18). The structure elucidation was based on spectroscopic analysis. Among them, 1,3-dihydroxyphenyl-2-O-sulfate (13), 2,3,4-trihydroxybenzoic acid (16) and 3,3′,4,4′-tetrahydroxybiphenyl (18) are reported from tea plants for the first time. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Seismic behavior of SRC column–steel truss beam hybrid joint is investigated. [•] Structural mechanism and failure modes of the joint are revealed. [•] Beam flexural failure yields better seismic behavior than joint shear failure. [•] Design formula for shear strength of joint core is proposed. [•] Method for controlling failure mode is presented for strong joint/weak member goal. [Copyright &y& Elsevier]

Abstract: Based on the research of the companion paper, the influence of the slab spatial composite effect on the lateral stiffness and internal force distributions of composite frame structures has been investigated. The critical factors influencing the equivalent stiffness of composite beams are firstly analyzed using beam-shell mixed element models. Furthermore, a parametric analysis is conducted to derive a simplified design formula of the composite beam stiffness amplification coefficient. The methods for considering the slip effect at the steel–concrete interface have also been discussed. Several regular and irregular composite frame system models with different parameters are used to sufficiently verify the reasonability of the proposed formula in this paper. It can be found that the proposed “line” element composite beam frame model considering the slab spatial composite effect can accurately predict the periods of natural vibration, the seismic story shear forces, the lateral displacements, the story drifts and the internal forces of composite beams etc. However, the model using the formula proposed by Eurocode 4 or neglecting the slab spatial composite effect may give unsatisfactory predictions. Finally, five experimental programs of the composite frames are selected to validate the design methods proposed in this and the companion paper. It can be concluded that the proposed design method in this research can be used to more accurately consider the influence of the slab spatial composite effect in the routine design practice of composite frame systems compared with other methods proposed in the literature and the current design codes. [Copyright &y& Elsevier]

Abstract: The slab spatial composite effect plays a significant role in the behavior of composite frame structural systems subjected to lateral forces. Since the ultimate loading capacity and stiffness are the two most basic characteristic behaviors in a design practice, this paper focuses on the influence of the slab spatial composite effect on the ultimate loading capacity, and the companion paper pays attention to the structural stiffness and internal force distribution. The extensive verifications of the proposed design methods for evaluating the ultimate loading capacity and stiffness considering the slab spatial composite effect based on various numerical examples and experimental programs are also carried out in the companion paper. In this paper, an elasto-plastic elaborate finite element model of the side joint is firstly developed in order to find the critical factors dominating the slab participation at the ultimate limit states. Furthermore, a parametric analysis is conducted to derive the simplified design formulas of the slab effective widths for calculating the ultimate positive and negative moments at the composite beam end. The predictions calculated using the proposed formulas correlate well with the numerical results. In addition, the proposed design methods are verified adapted for both side and middle joints. Finally, the proposed formulas are compared with some available formulas provided in the literature and current design codes. It is found that the proposed formulas can give the most satisfactory results for predicting the ultimate effective width and beam end moments. [Copyright &y& Elsevier]

The expansion of DNA repeat sequences is associated with many genetic diseases in humans. Simple bulge DNA structures have been implicated as intermediates in DNA slippage within the DNA repeat regions. To probe the possible role of bulged structures in DNA slippage, we designed and synthesized a pair of simple chiral spirocyclic compounds [Xi Z, Ouyang D & Mu HT (2006) Bioorg Med Chem Lett 16, 1180–1184], DDI-1A and DDI-1B, which mimic the molecular architecture of the enediyne antitumor antibiotic neocarzinostatin chromophore. Both compounds strongly stimulated slippage in various DNA repeats in vitro. Enhanced slippage synthesis was found to be synchronous for primer and template. CD spectra and UV thermal stability studies supported the idea that DDI-1A and DDI-1B exhibited selective binding to the DNA bulge and induced a significant conformational change in bulge DNA. The proposed mechanism for the observed in vitro expansion of long DNA is discussed. [ABSTRACT FROM AUTHOR]

• The S-C–W-B criterion is inadequate for avoiding the column hinges in RC frames. • A biaxial bending strength model of RC columns under axial load is developed. • A biaxial overstrength factor is proposed to improve the S-C–W-B criterion. • The inelastic response of RC frames under biaxial seismic excitation is investigated. • The effect of the biaxial overstrength factor is validated by FEM analysis. In several earthquakes, numerous reinforced concrete (RC) frames subjected to seismic excitation exhibit a collapse pattern characterised by column hinges, although these frames are designed according to the strong-column–weak-beam (S-C–W-B) criterion. The effect of biaxial seismic excitation on the disparity between the design and the actual performance of RC frames is investigated in this study. First, a modified load contour method was proposed to derive a closed-form equation of the biaxial bending moment strength, which was verified based on numerical and experimental results. Subsequently, a group of time-history analyses of a simple frame modelled using fibre beam-column elements subjected to biaxial seismic excitation were conducted to verify that the current S-C–W-B criterion is inadequate for preventing the occurrence of column hinges. A biaxial overstrength factor was developed based on the proposed equation, and the reinforcement of columns was appropriately amplified using this factor to prevent the occurrence of column hinges under biaxial excitation; this approach was proved to be effective through another group of time-history analyses. Thus, the findings of this study can serve as a basis for improving the seismic design of RC frames, which will enable the construction of safer engineering structures. [ABSTRACT FROM AUTHOR]

An innovative composite structural system with separated gravity and lateral resisting systems (SGLR system) was proposed to overcome the shortcomings of existing prefabricated structural systems. Two representative frame specimens with a scale ratio of 0.5 were tested under vertical floor loads and lateral cyclic loads to investigate the mechanical behaviour of the SGLR system. The slab crack patterns, failure modes, load–displacement curves, strength and stiffness degradations, energy dissipation capacity, deformation characteristics and strain development were analysed. The experimental results showed that the bent frame specimen (SGLR-1) exhibited good and stable seismic performance and the shear wall–bent frame (SGLR-2) with higher stiffness and capacity demonstrated obvious degradation due to buckling and fracture of steel plates at the bottom of shear walls. From test observations, flexural deformation was the dominated deformation pattern of the SGLR system under lateral loads. On the basis of test data, seismic performance assessment indicated that the SGLR system had larger safety margin than the conventional composite rigid frame (RF) system with the same design criteria of inter-storey drift ratios. The internal force analysis of the SGLR system showed that the base shear distribution in shear walls and columns varied with the increase of overall drift ratio. Moreover, it was revealed from the experimental analysis that the semi-rigidity of connections was significant and had conspicuous influence on both gravity and lateral force transfer mechanisms of the SGLR system. Unlabelled Image • An innovative structural system is proposed to improve prefabricated construction. • Tests on two representative frame specimens with a 0.5 scale ratio are conducted. • The new system has larger safety margin than the conventional rigid frame system. • The base shear distribution in walls and columns varies with loading amplitude. • Semi-rigidity of connections is significant and affects force transfer mechanisms. [ABSTRACT FROM AUTHOR]

• A test on a large-scale composite frame with wide floor slabs is conducted. • The effect of floor loads on the seismic behaviour of the frame is considered. • The weld fracture near exterior joints impacts the global performance greatly. • The effective slab width is 0.75 times column width with obvious shear lag effect. • Deformation characteristics and force mechanism under cyclic loading are discussed. The steel–concrete composite frame systems are widely used in multistory and high-rise buildings owing to good mechanical performance and high construction efficiency. In previous research on the composite frame systems, many lateral cyclic tests were conducted on specimens with small-width floor slabs without floor loads, which could not precisely reflect the actual behaviour of composite frames in spatial multistory buildings. Therefore, this paper presents an experimental study on the seismic behaviour of composite frames with wide floor slabs considering the effect of floor loads. The specimen was a two-story two-span composite frame with the scale ratio of 0.5, and three load cases, including the vertical floor loading test, the lateral cyclic loading test and the pushover test, were respectively applied to investigate the mechanical performance of the composite frame. The slab crack development, mid-span deflection and strain distribution of slab reinforcements in the vertical floor loading test were discussed. The overall responses of the specimen in the lateral cyclic loading test and pushover test were analysed, including failure phenomena, load–displacement curves, strength and stiffness degradation, energy dissipation capacity and deformation characteristics. Moreover, the seismic performance of columns, beams, slabs and joints in the specimen was discussed in detail and the force mechanism of the composite frame was revealed based on the structural analysis of components. The results indicated that the specimen exhibited sufficient load-bearing capacity, good ductility, stable strength and stiffness degradation and excellent energy dissipation capacity under the combination of vertical floor loads and lateral loads. The welds at the bottom flange near the exterior joint fractured under cyclic loading, which was found to have significant influence on the deformation pattern and force mechanism of the composite frame. The shear lag effect was obvious in the wide floor slabs and the effective width of the slabs was estimated to be nearly 0.75 times the column width. [ABSTRACT FROM AUTHOR]