Web crippling behaviour of laterally restrained cold-formed steel re-entrant profiled deckings

Web crippling failure is often found to be critical in cold-formed steel profiled deckings during construction of composite slabs. Therefore, accurate prediction to the web crippling resistances of profiled deckings over internal supports under hogging moment is highly desirable. This paper presents an extensive experimental investigation into the structural behaviour of laterally restrained re-entrant profiled deckings under concentrated loads. A total of 104 web crippling tests on fully supported re-entrant profiled deckings with nominal yield strengths at 235 and 550 N/mm² are carried out to provide data for direct comparison with design resistances obtained from codified design rules. It should be noted that in the past, little attention has been paid to establish the lateral restraint condition of profiled deckings under concentrated loads in tests. Hence, local section distortion or ‘section spreading’ is often observed in tests but seldom dealt with rigorously during design development. In the present study, effective lateral restraints are provided to the test specimens in order to fully mobilize the web crippling resistances of the profiled deckings. It is found that the measured web crippling resistances are typically 20%–40% higher than those obtained from the codified design rules given in BS5950: Part 6, Eurocode 3: Part 1.3 and the North America Specification, depending on the steel grades and thicknesses, the load bearing lengths as well as the loading conditions.

In general, both BS5950 and Eurocode 3 give conservative web crippling resistances for re-entrant profiled deckings with both low and high strength steel under internal and end loading conditions. Moreover, the corresponding resistance factors determined according to a codified reliability analysis are considerably larger than the required values. Thus, the design rules are reliable and conservative, although they tend to be very conservative for profiled deckings under end loading condition. However, an examination on the design rules given in the NAS shows that only some of them are applicable to predict the web crippling resistances of low and high strength steel re-entrant profiled steel deckings. The design rule for IOF condition always gives both conservative and reliable resistances for both low and high strength steel profiled deckings, compared to the measured values. The design rule for EOF condition is also found to be both conservative and reliable for low strength steel profiled deckings only, but not for high strength steel profiled deckings. The design rules for ITF and ETF conditions are not applicable for both low and high strength steel profiled deckings according to the reliability analyses.

It is demonstrated that a set of new design rules specifically for re-entrant profiled deckings is needed for both improved efficiency and reliability. Moreover, the comprehensive set of test data is readily adopted to calibrate both finite element models and design expressions in subsequent studies.     

Mode shape linearization and correction in coupled dynamic analysis of wind‐excited tall buildings

The three‐dimensional mode shapes found in modern tall buildings complicate the use of the high‐frequency base balance (HFBB) technique in wind tunnel testing for predicting their wind‐induced loads and effects. The linearized‐mode‐shape (LMS) method was recently proposed to address some of the complications in the calculation of the generalized wind forces, which serve as the input to modal analysis for predicting wind‐induced dynamic responses of tall buildings. An improved LMS method, called the advanced linearized‐mode‐shape (ALMS) method, is developed in this paper by introducing torsional mode shape corrections to account for the partial correlation of torques over building height. The ALMS method has been incorporated into the accurate complete quadratic combination method in the coupled dynamic analysis to form a comprehensive procedure for the determination of equivalent static wind loads (ESWLs) for structural design of complex tall buildings. The improved accuracy in the prediction of generalized forces by the ALMS method has been validated by a 60‐storey benchmark building with multiple‐point simultaneous pressure measurements. A practical 40‐storey residential building with significant swaying and torsional effects is presented to demonstrate the effectiveness of the proposed wind load and response analysis procedure based on the HFBB data. Copyright © 2010 John Wiley & Sons, Ltd.     

Ultrathin Polymeric Coatings Based on Hydrogen‐Bonded Polyphenol for Protection of Pancreatic Islet Cells

Though transplantation of pancreatic islet cells has emerged as a promising treatment for Type 1 diabetes its clinical application remains limited due to a number of limitations including both pathogenic innate and adaptive immune responses. This paper reports on a novel type of multifunctional cytoprotective material applied to coat living pancreatic islets. The coating utilizes hydrogen‐bonded interactions of a natural polyphenol (tannic acid) with poly(N‐vinylpyrrolidone) deposited on the islet surface via non‐ionic layer‐by‐layer assembly. It is demonstrated that the coating is conformal over the surface of mammalian islets including those derived from rat, non‐human primate (NHP), and human. In contrast to unmodified controls, the coated islets maintain their viability and β‐cell functionality for at least 96 hours in vitro. It is also determined that the coating demonstrates immunomodulatory cytoprotective properties suppressing pro‐inflammatory cytokine synthesis in stimulated bone marrow‐derived macrophages and diabetogenic BDC‐2.5 T cells. The coating material combines high chemical stability under physiologically relevant conditions with capability of suppressing cytokine synthesis, crucial parameters for prolonged islet integrity, viability, and function in vivo. This study offers new opportunities in the area of advanced multifunctional materials to be used for a cell‐based transplantation therapy     

Numerical simulation of a steam-injection pilot study for a PCP-contaminated aquifer

The following study was focused on the simulation of a steam-injection field pilottest conducted in our past research. The scope of research contained two main subjects: heat transfer and contaminant transport when steam was injected into a pentachlorophenol (PCP)-contaminated aquifer. Numerical simulation of the heat transfer during the field test showed that vertical permeability is more influential to the distribution of water temperature than the horizontal permeability. If the vertical permeability is relatively high, the steam in the aquifer has a higher tendency to migrate upward and cause the aquifer temperature to rise faster. The simulation results also showed that heat convection is very sensitive to the soil permeability. Therefore, high permeability media makes the effect of heat convection more important on applying the steam-injection method. Heat conduction dominates the heat transfer within the hot aqueous zone. However, the hot aqueous zone is relatively smaller than the steam zone when steam is injected into the aquifer. Therefore, heat conduction is not as important as heat convection within the steam zone, which is the same result observed in the field test. Specific heat of soil media is also a sensitive factor. A numerical simulator, T2VOC, was utilized to simulate the PCP transport in the aquifer when steam was injected into the aquifer. The results showed that the shape of PCP distribution was identical to that of steam. It illustrated thatthe steam carried PCP upward and laterally. The high vertical soil permeability causes the steam to migrate upward with PCP easily. A low partitioning coefficient allows PCP to be desorbed easier, also an important factor. A majority of the PCP in the soil was transferred to the aqueous phase as the water temperature increased, showing similar results to those observed in the field test. According to the sensitivity analysis, PCP transport is more sensitive to the vertical permeability than the partitioning coefficient. The steam-injection rate is also an important operation parameter and may determine the success of the remediation work.     

Optical and acoustic detection of laser-generated microbubbles in single cells

Acoustically monitored laser-induced optical breakdown (LIOB) has potential as an important tool to diagnose and treat living cells. Laser-induced intracellular microbubbles are readily detectable using high-frequency ultrasound, and LIOB can be controlled to operate within two distinct regimes. In the nondestructive regime, a single, short-lived bubble can be generated within a cell, without affecting its immediate viability. In the destructive regime, the induced photodisruption quickly can kill a targeted cell. To generate and monitor this range of bioeffects in real time, we have developed a system integrating an ultrafast laser source with optical and acoustic microscopy. Experiments were performed on monolayers of Chinese hamster ovary (CHO) cells. A 793 nm, 100 fs laser pulsed at 3.8 kHz was tightly focused within each cell to produce the photodisruption, and a 50 MHz ultrasonic transducer monitored the resultant bubble via continuous pulse-echo recordings. Photodisruption was also observed using bright field microscopy, and cell viability was assessed following laser exposure with a trypan blue assay. By controlling laser pulse fluence and exposure duration, either nondestructive or destructive LIOB could be produced. The intracellular position of the laser focus was also varied to demonstrate that cell viability was affected by the specific location of material breakdown.     

Temperature Measurement Technique for Stabilizing the Light Output of RGB LED Lamps

The efficiency of light-emitting-diode (LED) lights approaches that of fluorescent lamps. LED light sources find more applications than conventional light bulbs due to their compactness, lower heat dissipation, and real-time color-changing capability. Stabilizing the colors of red–green–blue (RGB) LED lights is a challenging task, which includes color light intensity control using switching-mode power converters, color point maintenance against LED junction temperature change, and limiting LED device temperature to prolong the LED lifetime. In this paper, we present a LED junction temperature measurement technique for a pulsewidth modulation diode forward current controlled RGB LED lighting system. The technique has been automated and can effectively stabilize the color without the need for using expensive feedback systems that involve light sensors. Performance in terms of chromaticity and luminance stability for a temperature-compensated RGB LED system will be presented.      

Compressive damage in filament‐wound carbon/carbon composites

The processing characteristics and the induced compressive damage in filament‐wound carbon/carbon composites were examined. Tubular carbon/phenolic composites were made by the filament winding method. The inside diameter was 25.4 mm and the nominal thickness was 2.5 mm. The cured composites were then carbonized. Three more cycles of matrix densification were repeated. After densification, the composites were graphitized at 2600°C. Compressive tests were then carried out for the cured, carbonized, and graphitized composites. The load was applied directly on the end of the tube. The loading response and the induced damage were studied. Their microscopic fracture behaviors were examined by optical and scanning electron microscopes. With the heating temperature increased, the damage modes shifted from a ductile fracture in the cured composites to a more brittle fracture in the graphitized composites. The resulting strength and stiffness were also decreased significantly with the temperature. Kinking of fibers was the major mode in the cured specimens, while separation of bundles became more prominent in the graphitized specimens. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Molecularly Imprinted Polymers as Synthetic Antibodies for Protein Recognition: The Next Generation

Molecularly imprinted polymers (MIPs) are chemical antibody mimics obtained by nanomoulding the 3D shape and chemical functionalities of a desired target in a synthetic polymer. Consequently, they possess exquisite molecular recognition cavities for binding the target molecule, often with specificity and affinity similar to those of antigen-antibody interactions. Research on MIPs targeting proteins began in the mid-90s, and this review will evaluate the progress made till now, starting from their synthesis in a monolith bulk format through surface imprinting to biocompatible soluble nanogels prepared by solid-phase synthesis. MIPs in the latter format will be discussed more in detail because of their tremendous potential of replacing antibodies in the biomedical domain like in diagnostics and therapeutics, where the workforce of antibodies is concentrated. Emphasis is also put on the development of epitope imprinting, which consists of imprinting a short surface-exposed fragment of a protein, resulting in MIPs capable of selectively recognizing the whole macromolecule, amidst others in complex biological media, on cells or tissues. Thus selecting the ‘best’ peptide antigen is crucial and in this context a rational approach, inspired from that used to predict peptide immunogens for peptide antibodies, is described for its unambiguous identification.     

Multiplex Single-Cell Analysis of Cancer Cells Enables Unbiased Uncovering Subsets Associated with Cancer Relapse: Heterogeneity of Multidrug Resistance in Precursor B-ALL

Earlier detection of biomarkers responsible for cancer relapse facilitates more rational cancer treatment regimens to be designed. Herein, we develop a mass cytometry-based strategy for unbiased mining of cell subsets that potentially contribute to cancer recurrence through panoramic examination of the immunophenotypic features and multidrug resistance characteristics. The incorporation of metal tags enables multiplexed information of single cells to be interrogated based on metal fingerprint. Using acute lymphoblastic leukemia (B-ALL) as a showcase, we show overexpressed multidrug resistance biomarkers, i. e., BCRP, Bcl-2, MRP1, and P-gp in B-ALL cells compared with healthy control, and a positive correlation among different multidrug resistance biomarkers. Different cell subsets with multidrug resistance are well-defined, featured with CD34⁺CD38⁺CD10⁻ and CD34⁺CD38^+/intCD10⁺. Importantly, we uncovered that CD34 expression level is positively correlated to multidrug resistance, indicative of a higher potential of immature cells to induce B-ALL relapse. In addition, the cell subsets positively expressing CD73 and CD304 (CD34⁺CD10⁺CD304⁺; CD34⁺CD38^+/intCD10⁺CD73⁺) also overexpress multidrug resistance biomarkers, suggesting that they may serve as additional new biomarkers for B-ALL stratification and prognosis. Our data provide the first evidence that highly expressed multidrug resistance biomarkers in certain cell subpopulations with specific immunophenotypes may potentially induce B-ALL recurrence. The incorporation of multidrug resistance features with cell phenotypes using mass cytometry proposed in this study provides a general strategy for risk assessment and the prediction of recurrence of different types of cancers.     

Molecularly Imprinted Polymer Hydrogel Nanoparticles: Synthetic Antibodies for Cancer Diagnosis and Therapy

Cancer is a leading cause of death worldwide and according to the World Health Organization (WHO) accounted for 10 million deaths in 2020. Promising theranostic (therapy and diagnostic) agents in the treatment of cancer are nanomaterials, which have come to the forefront because of their small size approaching those of protein complexes in the human body, and of their easy functionalization giving access to nanocomposite materials with diverse functions (fluorescence, magnetic, stimuli-responsiveness, etc.), and improved biocompatibility. Among them, affinity nanoparticles, often decorated with highly specific targeting ligands such as antibodies, aptamers, lectins and peptides, have enabled enhanced binding and exquisite recognition of biomarkers overexpressed in cancer cells. In this review, we describe an emerging class of targeting ligands, molecularly imprinted polymer hydrogel nanoparticles for their application in the early detection of disease, with the aim to improve diagnosis and treatment.