Exceptional Early Jurassic fossils with leathery eggs shed light on dinosaur reproductive biology.

Our understanding of pre-Cretaceous dinosaur reproduction is hindered by a scarcity of evidence within fossil records. Here we report three adult skeletons and five clutches of embryo-containing eggs of a new sauropodomorph from the Lower Jurassic of southwestern China, displaying several significant reproductive features that are either unknown or unlike other early-diverging sauropodomorphs, such as relatively large eggs with a relatively thick calcareous shell formed by prominent mammillary cones, synchronous hatching and a transitional prehatching posture between the crocodilians and living birds. Most significantly, these Early Jurassic fossils provide strong evidence for the earliest known leathery eggs. Our comprehensive quantitative analyses demonstrate that the first dinosaur eggs were probably leathery, elliptical and relatively small, but with relatively long eggshell units, and that along the line to living birds, the most significant change in reptilian egg morphology occurred early in theropod evolution rather than near the origin of Aves.

Bioinspired Separator with Ion-Selective Nanochannels for Lithium Metal Batteries.

The free transport of anions through commercial polyolefin separators used in lithium metal batteries (LMBs) gives rise to concentration polarization and rapid growth of lithium dendrites, leading to poor performance and short circuits. Here, a new poly(ethylene-co-acrylic acid) (EAA) separator with functional active sites (i.e., carboxyl groups) distributing along the pore surface was fabricated, forming bioinspired ion-conducting nanochannels within the separator. As the carboxyl groups effectively desolvated Li+ and immobilized anion, the as-prepared EAA separator selectively accelerated the transport of Li+ with transference number of Li+ (tLi+) up to 0.67, which was further confirmed by molecular dynamics simulations. The battery with the EAA separator can be stably cycled over 500 h at 5 mA cm-2. The LMBs with the EAA separator have exceptional electrochemical performance of 107 mAh g-1 at 5 C and a capacity retention of 69% after 200 cycles. This work provides new commercializable separators toward dendrite-free LMBs.

One-pot synthesis of hyperbranched polymers via visible light regulated switchable catalysis.

Switchable catalysis promises exceptional efficiency in synthesizing polymers with ever-increasing structural complexity. However, current achievements in such attempts are limited to constructing linear block copolymers. Here we report a visible light regulated switchable catalytic system capable of synthesizing hyperbranched polymers in a one-pot/two-stage procedure with commercial glycidyl acrylate (GA) as a heterofunctional monomer. Using (salen)CoIIICl (1) as the catalyst, the ring-opening reaction under a carbon monoxide atmosphere occurs with high regioselectivity (>99% at the methylene position), providing an alkoxycarbonyl cobalt acrylate intermediate (2a) during the first stage. Upon exposure to light, the reaction enters the second stage, wherein 2a serves as a polymerizable initiator for organometallic-mediated radical self-condensing vinyl polymerization (OMR-SCVP). Given the organocobalt chain-end functionality of the resulting hyperbranched poly(glycidyl acrylate) (hb-PGA), a further chain extension process gives access to a core-shell copolymer with brush-on-hyperbranched arm architecture. Notably, the post-modification with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) affords a metal-free hb-PGA that simultaneously improves the toughness and glass transition temperature of epoxy thermosets, while maintaining their storage modulus.

Advances on Thermally Conductive Epoxy-Based Composites as Electronic Packaging Underfill Materials-A Review.

The integrated circuits industry has been continuously producing microelectronic components with ever higher integration level, packaging density, and power density, which demand more stringent requirements for heat dissipation. Electronic packaging materials are used to pack these microelectronic components together, help to dissipate heat, redistribute stresses, and protect the whole system from the environment. They serve an important role in ensuring the performance and reliability of the electronic devices. Among various packaging materials, epoxy-based underfills are often employed in flip-chip packaging. However, widely used capillary underfill materials suffer from their low thermal conductivity, unable to meet the growing heat dissipation required of next-generation IC chips with much higher power density. Many strategies have been proposed to improve the thermal conductivity of epoxy, but its application as underfill materials with complex performance requirements is still difficult. In fact, optimizing the combined thermal-electrical-mechanical-processing properties of underfill materials for flip-chip packaging remains a great challenge. Herein, state-of-the-art advances that have been made to satisfy the key requirements of capillary underfill materials are reviewed. Based on these studies, the perspectives for designing high-performance underfill materials with novel microstructures in electronic packaging for high-power density electronic devices are provided.

Grafting Polytetrafluoroethylene Micropowder via in Situ Electron Beam Irradiation-Induced Polymerization.

Decreasing the surface energy of polyacrylate-based materials is important especially in embossed holography, but current solutions typically involve high-cost synthesis or encounter compatibility problems. Herein, we utilize the grafting of polytetrafluoroethylene (PTFE) micropowder with poly (methyl methacrylate) (PMMA). The grafting reaction is implemented via in situ electron beam irradiation-induced polymerization in the presence of fluorinated surfactants, generating PMMA grafted PTFE micropowder (PMMA⁻g⁻PTFE). The optimal degree of grafting (DG) is 17.8%. With the incorporation of PMMA⁻g⁻PTFE, the interfacial interaction between polyacrylate and PTFE is greatly improved, giving rise to uniform polyacrylate/PMMA⁻g⁻PTFE composites with a low surface energy. For instance, the loading content of PMMA⁻g⁻PTFE in polyacrylate is up to 16 wt %, leading to an increase of more than 20 degrees in the water contact angle compared to the pristine sample. This research paves a way to generate new polyacrylate-based films for embossed holography.

Superior flame retardancy and smoke suppression of epoxy-based composites with phosphorus/nitrogen co-doped graphene.

Phosphorus and/or nitrogen doping is an effective method of improving the physical and chemical properties of reduced graphene oxide (rGO). In this work, phosphorus and nitrogen co-doped rGO (PN-rGO), synthesized using a scalable hydrothermal and microwave process, was used as an additive to improve the flame retardancy of epoxy resin (EP) for the first time. Chemical structure and morphology characterization confirmed that the nitrogen and phosphorus atoms were doped into the graphite lattice adopting pyrrolic-N, pyridinic-N, quaternary-N and pyrophosphate and metaphosphate forms. Doping increased the oxidization resistance of rGO and the thermal-oxidative stability of its composites' char, while also improving the catalytic charring ability of polymer. Both effects resulted in the formation of a stable char protective layer during burning and to a significant improvement in flame retardation and smoke suppression in the final composites. The peak heat release rate (PHRR), total heat release (THR) and total smoke production (TSP) for the EP-based composite (containing 5 wt% PN-rGO) decreased by 30.9%, 29.3% and 51.3%, respectively, compared to neat EP. Our work has produced a promising graphene-based flame retardant additive for the mass production of high-performance composites, also expended the application of heteroatom-doped graphene.

Efficacy and safety of therapeutic angiogenesis from direct myocardial administration of an adenoviral vector expressing vascular endothelial growth factor 165.

OBJECTIVE: To investigate whether direct administration of adenoviral vectors (Ad) containing the complementary deoxyribonucleic acid (cDNA) of vascular endothelial growth factor 165 (Ad-VEGF165) induces porcine coronary collateral vessel formation, improves regional myocardial perfusion and function and is safe. METHODS: Three weeks after miniature swine underwent left thoracotomy and placement of an Ameroid constrictor on the left circumflex coronary artery (LCX), Ad-VEGF165 (n = 6) or the control, Ad expressing beta-galactosidase cDNA (Ad-Gal, n = 6), was directly administered into the ischemic myocardium in the circumflex distribution. All animals were sacrificed 4 wk after the second surgery. Myocardial perfusion and function were assessed by electrocardiogram-gated single photon emission computed tomography (GSPECT) imaging. Ex vivo coronary angiography was performed to examine collateral vessels. Toxicity was assessed by blood analyses on the day just before (day 0) and on day 1, 3, 7, 28 after vector delivery and by vascular, myocardial and liver histology after sacrifice. RESULTS: GSPECT imaging 4 wk after administration of Ad-VEGF165 demonstrated significant reduction in ischemic area (P < 0.01) and rest ischemic severity (P < 0.01) and significant improvement in the left ventricular ejection fraction (P < 0.01) and regional wall motion (P < 0.05) compared with that of Ad-Gal and before administration of Ad-VEGF165. Collateral vessel development assessed by coronary angiography was significantly greater in the Ad-VEGF165 group than in the Ad-Gal group (P < 0.05). General safety parameters, including routine blood parameters, liver and kidney function and cardiac specific parameters demonstrated no difference between Ad-VEGF165 and Ad-Gal animals except for the red blood cell count on day 28 (P < 0.05) and blood urea nitrogen on day 7 (P < 0.05). Only transient elevations in creatine phosphokinase (P < 0.05) and aspartate transaminase (P < 0.05) on day 1 were revealed compared with that before vector administration in both groups. Histologically, no atherosclerotic lesion in the circumflex and no inflammation in liver were revealed and only a small myocardial necrosis was observed in one Ad-VEGF165 animal (area < or = 20%) and one Ad-Gal animal (area < 10%). CONCLUSIONS: Ad-VEGF165 can induce coronary collateral vessel formation, improve regional myocardial perfusion and function and is safe by means of direct injection, which suggesting that this strategy may be useful in treating human ischemic heart disease.