Photo‐Crosslinked Side‐Chain Liquid‐Crystalline Elastomers for Microsystems

Photo‐crosslinkable side‐chain liquid‐crystalline polymers (LCPs) containing photoreactive benzophenone cores are synthesized in order to obtain their corresponding side‐chain liquid‐crystalline elastomers (LCEs). This strategic synthesis allows thin elastomeric films and their integration into microsystems for actuators and micromachines to be obtained. As an example of this principle, a gripper was developed. The position of its arms can be changed by applying voltages from 1.5 to 3.5 V at different rates. Small changes in the liquid‐crystalline elastomer film cause strains of up to 150% in the microdevice and the capacity to move up to 400 times its own mass due to the nematic‐to‐isotropic transformation.

     

Fluorene‐Based Single‐Chain Copolymers for Color‐Stable White Light‐Emitting Diodes

Fluorene‐based single‐chain copolymers with a white light emitter consisting of a blue and an orange chromophore have been synthesized and their photophysical and electroluminescent properties are investigated. The experimental results suggest that only a relatively small fraction of the orange‐emitting units incorporated into the fluorene is needed to achieve efficient white light emission by controlled incomplete energy transfer. A device from a copolymer with 0.02% DDQ content showed the highest external quantum efficiency of 2.64% with a luminance efficiency of 4.06 cd · A^?1 with CIE coordinates (0.28, 0.24). The EL emissions are extremely stable over a wide range of current densities.

     

Image‐guided radio‐frequency gain calibration for high‐field MRI

High‐field (≥ 3T) MRI provides a means to increase the signal‐to‐noise ratio, due to its higher tissue magnetization compared with 1.5T. However, both the static magnetic field (B₀) and the transmit radio‐frequency (RF) field (B) inhomogeneities are comparatively higher at higher field strengths than those at 1.5T. These challenging factors at high‐field strengths make it more difficult to accurately calibrate the transmit RF gain using standard RF calibration procedures. An image‐based RF calibration procedure was therefore developed, in order to accurately calibrate the transmit RF gain within a specific region‐of‐interest (ROI). Using a turbo fast low‐angle shot (TurboFLASH) pulse sequence with centric k‐space reordering, a series of ‘saturation‐no‐recovery’ images was acquired by varying the flip angle of the preconditioning pulse. In the resulting images, the signal null occurs in regions where the flip angle of the preconditioning pulse is 90°. For a given ROI, the mean signal can be plotted as a function of the nominal flip angle, and the resulting curve can be used to quantitatively identify the signal null. This image‐guided RF calibration procedure was evaluated through phantom and volunteer imaging experiments at 3T and 7T. The image‐guided RF calibration results in vitro were consistent with standard B₀ and B maps. The standard automated RF calibration procedure produced approximately 20% and 15–30% relative error in the transmit RF gain in the left kidney at 3T and brain at 7T, respectively. For initial application, a T₂ mapping pulse sequence was applied at 7T. The T₂ measurements in the thalamus at 7T were 60.6 ms and 48.2 ms using the standard and image‐guided RF calibration procedures, respectively. This rapid, image‐guided RF calibration procedure can be used to optimally calibrate the flip angle for a given ROI and thus minimize measurement errors for quantitative MRI and MR spectroscopy. Copyright © 2009 John Wiley & Sons, Ltd.     

IL‐27p28 is essential for parent‐to‐F1 acute graft‐versus‐host disease

Acute graft versus host disease (aGVHD) remains a life‐threatening complication of bone marrow transplantation. Here we show that IL‐27, a member of the IL‐12 cytokine family, plays an essential role in a parent‐to‐F1 murine aGVHD model, using B6 mice as parents and B6D2 mice as F1 recipients. IL‐27 is transiently detectable in the serum of B6D2 recipients of B6 spleen cells, with a peak at day 10. Treatment with anti‐IL‐27p28 mAb MM27.7B1 (αp28Ab), at the time of and six days after B6 cell transfer, blocked GVHD. Protection was associated with host cell survival and undiminished engraftment of donor cells, lack of host B‐cell depletion, increased Th2‐type immunoglobulin production, a decrease in serum IFN‐γ, a drop in anti‐H‐2D^d cytotoxic T lymphocyte activity and an increase in Foxp3⁺ T cells. We therefore conclude that IL‐27 plays a critical role in the parent‐to‐F1 model of aGVHD and that blocking IL‐27 could have therapeutic relevance.     

Syntheses of Biaxially Extended Octithiophene‐Based Conjugated Copolymers for High‐Open‐Circuit‐Voltage Photovoltaic‐Cell Applications

Novel biaxially extended octithiophene (8T)‐based conjugated polymers are successfully ­synthesized using Stille coupling reactions of the branched octithiophene moiety with seleno­phene (P8TSe), thiophene (P8TT), and thieno[3,2‐b]thiophene (P8TTT). The 8T moiety can signifi­cantly lower the highest occupied molecular orbital (HOMO) level and leads to an enhanced open‐circuit voltage because of the branched conformation. The power conversion efficiencies (PCE) of the polymer/[6,6]‐phenyl‐C71‐butyric acid methyl ester PC₇₁BM photovoltaic cells are in the range of 1.28–2.30%. In particular, the P8TTT‐based device processed from an o‐dichlorobenzene/1,8‐diiodoctane mixed solvent shows the best PCE among the studied polymers (2.81%), demonstrating that 8T‐based polymers with a low HOMO level can emerge as promising candidates for organic device applications.

     

In‐laboratory diffraction‐enhanced X‐ray imaging for articular cartilage

The loss of articular cartilage characteristic of osteoarthritis can only be diagnosed by joint space narrowing when conventional radiography is used. This is due to the lack of X‐ray contrast of soft tissues. Whereas conventional radiography harnesses the X‐ray attenuation properties of tissues, Diffraction Enhanced Imaging (DEI), a novel radiographic technique, allows the visualization of soft tissues simultaneous with calcified tissues by virtue of its ability to not only harness X‐ray attenuation but also the X‐ray refraction from tissue boundaries. Previously, DEI was dependent upon synchrotron X‐rays, but more recently, the development of nonsynchrotron DEI units has been explored. These developments serve to elaborate the full potential of radiography. Here, we tested the potential of an in‐laboratory DEI system, called Diffraction‐Enhanced X‐ray Imaging (DEXI), to render images of articular cartilage displaying varying degrees of degradation, ex vivo. DEXI allowed visualization of even early stages of cartilage degeneration such as surface fibrillation. This may be of eventual clinical significance for the diagnosis of early stages of degeneration, or at the very least, to visualize soft tissue degeneration simultaneous with bone changes. Clin. Anat. 23:530–538, 2010. © 2010 Wiley‐Liss, Inc.     

Crosslinked polymer gels for boron extraction derived from N‐glucidol‐N‐methyl‐2‐hydroxypropyl methacrylate

Glycidyl methacrylate was reacted in 2‐methyl pyrrolidone solution with N‐methyl‐D ‐glucamine (NMG) to produce N‐D ‐glucidol, N‐methyl‐2‐hydroxy propyl methacrylate (GMHP). The reaction proceeded exclusively via ring opening of the oxirane. The resulting vinyl monomer was a waxy product and soluble in water, ethanol, methanol, DMF, and NMP. Copolymerization of GMHP with N,N′‐tetraallyl piperazinium dichloride by the inverse suspension method (water in oil), using a toluene/chloroform (3 : 1) mixture as continuous phase, led to crosslinked hydrogels in imperfect bead form. Crosslinking was also achieved without using additional crosslinker. Heating of N‐methyl‐D ‐glucamine with 10% excess of glycidyl methacrylate in NMP at 60°C for 4 h, resulting the formation of N‐methyl‐D ‐glucamine carrying two methacrylate groups. These dimethacrylate groups serve as a crosslinking agents. In situ redox polymerization of the mixture in water led to transparent hydrogels. These hydrogels in the swollen state have been demonstrated to be very efficient sorbents for the removal of boron on ppm levels. The boron loaded polymers can be regenerated by simple acid (0.1 M HCl) and base (0.1 M NaOH) treatment.     

Candidate region for cardio‐facio‐cutaneous syndrome

The breakpoints of deletions and translocations in the proximal chromosome 14q region were defined in nine patients, four of whom have not been reported previously. The aberrant chromosomes were isolated by flow cytometry and used to map the chromosome 14 deletion or translocation breakpoints. The parental origins of deletions were ascertained as paternal in five cases and maternal in one. With the draft genomic sequence for human chromosome 14 available, gene searches were performed on selected intervals of the 14q11.2–q21 region to identify candidate genes for the observed phenotype in some of those affected. Gain of function of the gene PAX9 on chromosome 14 is a possible candidate for a t(14;18) patient affected with mesomelic bone dysplasia. Furthermore, a compilation of other human chromosome 14q proximal deletion and translocation cases was obtained from a search on cytogenetic databases. These findings suggest a locus for myelofibrosis at chromosome 14q13. This study contributes to useful information for identifying disease genes in this region. © 2001 Wiley‐Liss, Inc.     

Highly Water‐Soluble Alpha‐Hydroxyalkylphenone Based Photoinitiator for Low‐Migration Applications

In this study, the bifunctional hydroxyketone based photoinitiator (PI) 1,1′‐{[(2,3‐dihydroxybutane‐1,4‐diyl)bis(oxy)]bis(4,1‐phenylene)}bis(2‐hydroxy‐2‐methylpropan‐1‐one) (Di‐PI) is synthesized with the aim to facilitate a highly photoactive water‐soluble PI which offers high migration stability. Di‐PI provides a five times higher water‐solubility than the state of the art water soluble PI 2‐hydroxy‐1‐[3‐(hydroxymethyl)phenyl]‐2‐methyl‐1‐propanone (I2959). Photo differential scanning calorimetry (Photo‐DSC) measurements reveal that the curing speed and conversion of N‐acroylmorpholine (NAM) in aqueous solution containing 0.5 mol% of Di‐PI are only slightly lower than formulations containing the reference PI I2959 in a concentration of 1 mol%. Most importantly, Di‐PI offers almost identical activity in dipropylene glycol diacrylate (DPDA) as I2959, although its migration from cured DPDA is significantly reduced by a factor of 7.6 compared to I2959.

     

A group‐specific sequence‐based typing approach for HLA‐DQA1

An HLA‐DQA1 sequence‐based typing method reliant upon group‐specific amplification to achieve an unambiguous second‐field DQA1 typing assignment is presented. Method validation, using 51 reference DNA samples covering 21 different DQA1 alleles, showed 100% concordance with the reference types. This typing strategy has several important uses including identifying DQA1 mismatches in kidney donor/recipient pairs to inform patient DQ antibody assignments.     

Tunable High‐Molecular‐Weight Anion‐Exchange Membranes for Alkaline Fuel Cells

Tunable alkaline anion‐exchange membranes based on QPMBV are synthesized using a bottom‐up approach, miniemulsion copolymerization, which can incorporate functional groups into the copolymers with designated composition and high molecular weight. The mechanical and electrochemical properties of the obtained QPMBV membranes are tuned by varying the composition. It is found that the ion exchange capacity of the copolymer, the hydrophilicity of the copolymer chains, the molecular weight, and the glass transition temperature of the copolymers are essential to balance the mechanical and OH^– transport properties of QPMBV membranes. QPMBV membrane fuel cells show the best power output and the long‐lasting fuel cell performance among the APE membranes in open literature.

     

Novel Sulfur‐Containing Cross‐Linking Agent for Si‐Based Preceramic Polymers

Cross‐linking polymethylhydrosiloxane (PMHS) with divinylthiophene (DVT) via hydrosilylation in highly dilute conditions and subsequent supercritical drying in CO₂ yield a polymeric aerogel containing aromatic sulfur integrally and uniformly distributed throughout the monolith. Fourier‐transform infrared (FT‐IR) spectroscopy indicates almost complete consumption of vinyl groups and Si? H bonds in the product. Both FT‐IR and Raman spectroscopic analyses support loss of conjugation of vinyl groups with the retained double bonds of the thiophene ring. Scanning electron microscopy (SEM) indicates a condensed colloidal structure with characteristic particulate diameters of about 165 nm. SEM coupled with energy dispersive X‐ray spectroscopy elemental mapping shows that sulfur is distributed homogeneously in the polymeric aerogel. Porosimetry of the mesoporous aerogel indicates the effective average pore diameters are about 12 nm. Thermogravimetric analysis (TGA) establishes greater thermal stability of the PMHS‐DVT product than either of the pure unreacted components. TGA coupled with mass spectrometric (TG‐MS) identification of the volatiles released during pyrolysis shows that sulfur is driven from the cross‐linked polymer as thiophene and its derivatives. Recorded mass spectra support the hypothesis that cross‐linking DVT bridges between PMHS chains in the polymeric aerogel, and that this results in a more thermally stable monolith.     

A Novel Poly(N‐Isopropylacrylamide‐co‐acryloylamidobenzo‐12‐crown‐4) Microgel with Rapid Stimuli‐Responsiveness for Molecule‐Specific Adsorption of γ‐Cyclodextrin

A novel poly(N‐isopropylacrylamide‐co‐acryloylamidobenzo‐12‐crown‐4) (PNB) microgel with rapid γ‐cyclodextrin (CD)‐responsive characteristics and adsorption property is developed. The microgel is composed of benzo‐12‐crown‐4 (B₁₂C₄) units as molecule‐recognition receptors and poly(N‐isopropylacrylamide) networks as phase‐transition actuators as well as adsorbent backbone chains. The PNB microgels significantly increase their volumes induced by γ‐CD, and adsorb γ‐CD molecules within PNB networks because of formation of γ‐CD/B₁₂C₄ inclusion complexes. Detection of γ‐CD‐concentration and the molecule‐specific adsorption processes of the microgels are investigated systematically. The PNB microgels provide a new tool for rapid concentration measurement and effective separation of γ‐CD.     

Diagnostic efficacy of anti‐SARS‐CoV‐2 IgG/IgM test for COVID‐19: A meta‐analysis

The serological testing of anti‐SARS‐CoV‐2 immunoglobulin G (IgG) and/or IgM is widely used in the diagnosis of COVID‐19. However, its diagnostic efficacy remains unclear. In this study, we searched for diagnostic studies from the Web of Science, PubMed, Embase, CNKI, and Wanfang databases to calculate the pooled diagnostic accuracy measures using bivariate random‐effects model meta‐analysis. As a result, 22 from a total of 1613 articles, including 2282 patients with SARS‐CoV‐2 and 1485 healthy persons or patients without SARS‐CoV‐2, were selected for a meta‐analysis. Pooled sensitivity, specificity, and area under curve of the summary receiver operator curve (SROC) were: (a) 0.85 (95% confidence interval [CI]: 0.79‐0.90), 0.99 (95% CI: 0.98‐1.00), and 0.99 (95% CI: 0.97‐0.99) for anti‐SARS‐CoV‐2 IgG and (b) 0.74 (95% CI: 0.65‐0.81), 0.99 (95% CI: 0.97‐1.00), and 0.95 (95% CI: 0.93‐0.97) for IgM. A subgroup analysis among detection methods indicated the sensitivity of IgG and IgM using enzyme‐linked immunosorbent assay were slightly lower than those using gold immunochromatography assay (GICA) and chemiluminescence immunoassay (P > .05). These results showed that the detection of anti‐SARS‐CoV‐2 IgG and IgM had high diagnostic efficiency to assist the diagnosis of SARS‐CoV‐2 infection. And, GICA might be used as the preferred method for its accuracy and simplicity.     

Synthesis and Characterization of a Phthalimide‐Containing Redox‐Active Polymer for High‐Voltage Polymer‐Based Redox‐Flow Batteries

A phthalimide‐containing redox‐active polymer is designed and synthesized in particular for the application in all‐organic redox‐flow batteries. 4‐Vinylbenzyl phthalimide is prepared in a one‐step reaction and copolymerized with a solubility promoting comonomer. The novel polymer is electrochemically characterized in various electrolytes via cyclic voltammetry and features a quasireversible reduction reaction at E⁰_½ = ?1.89 V versus AgNO₃/Ag. Afterward, the polymer is applied as anode‐active material in a first preliminary battery test in combination with a 2,2,6,6‐tetramethylpiperdinyl‐N‐oxyl‐containing polymer as cathode‐active material and a porous membrane as separator, yielding a polymer‐based all‐organic battery system with a high cell voltage of 2.0 V.     

Highly Air‐Stable Thieno[3,2‐b]thiophene‐Thiophene‐Thiazolo[5,4‐d]thiazole‐Based Polymers for Light‐Emitting Diodes

A series of highly air‐stable, low‐bandgap poly(3‐alkylthiophene)s containing electron‐rich thieno[3,2‐b]thiophene and electron‐deficient thiazolo[5,4‐d]thiazole rings were synthesized by the Stille coupling reaction. The polymers exhibited good thermal stability and solubility with excellent film forming properties when drop‐ or spin‐cast from solution. A strong absorption at 564–568 nm and a shoulder at 614–616 nm were observed. The optical bandgap of the polymers was found to be 1.82–1.85 eV. The IP of the polymers was found to be 5.62–5.65 eV. All polymers showed strong fluorescent emission both in solution and in the solid state. EL devices were fabricated using the polymers as an emissive layer and red emission was observed with the emission range of 649–679 nm.

     

2‐Naphthoxymethyl‐Substituted Polystyrenes for Homeotropic Liquid‐Crystal Alignment Layers

A series of 2‐naphthoxymethyl‐substituted polystyrenes (P2NAP) were prepared by the reaction of poly(chloromethylstyrene) with different amounts of 2‐naphthol to investigate the liquid‐crystal (LC) alignment properties of these polymer films. P2NAP with only 2‐naphthoxymethyl side groups (100% conversion of chloromethyl to 2‐naphthoxymethyl) was obtained when 180 mol‐% of naphthol was used in the reaction at 80 °C for 12 h. LC cells fabricated with unrubbed P2NAP films exhibited a homeotropic LC alignment behavior with a pretilt angle of approximately 90°. The homeotropic LC alignment behavior of the unrubbed LC cell of the P2NAP film was ascribed to the head‐on type incorporation of a nonpolar bulky 2‐naphthoxymethyl group into the phenyl side group of the polystyrene.