Simultaneous Crosslinking Research Articles

Disambiguation of Patent Inventors and Assignees Using High-Resolution Geolocation Data

Patent data represent a significant source of information on innovation and the evolution of technology through networks of citations, co-invention and co-assignment of new patents. A major obstacle to extracting useful information from this data is the problem of name disambiguation: linking alternate spellings of individuals or institutions to a single identifier to uniquely determine the parties involved in the creation of a technology. In this paper, we describe a new algorithm that uses high-resolution geolocation to disambiguate both inventor and assignees on more than 3.6 million patents found in the European Patent Office (EPO), under the Patent Cooperation treaty (PCT), and in the US Patent and Trademark Office (USPTO). We show that our algorithm has both high precision and recall in comparison to a manual disambiguation of EPO assignee names in Boston and Paris, and show it performs well for a benchmark of USPTO inventor names that can be linked to a high-resolution address (but poorly for inventors that never provided a high quality address). The most significant benefit of this work is the high quality assignee disambiguation with worldwide coverage coupled with an inventor disambiguation that is competitive with other state of the art approaches. To our knowledge this is the broadest and most accurate simultaneous disambiguation and cross-linking of the inventor and assignee names for a significant fraction of patents in these three major patent collections.

Simultaneous Sheet Cross-Linking and Deoxygenation in the Graphene Oxide Sol–Gel Transition

The precursor material to graphene aerogels is a hydrogel formed from an aqueous solution of graphene oxide. We investigate the time evolution of the physical and chemical properties of a graphene oxide suspension as it transitions to a hydrogel. Fully formed hydrogels undergo densification during reaction, forming mechanically stable monoliths. We demonstrate that the gelation process removes oxygen functional groups, partially re-forms the sp2 network, and creates bonds between graphene oxide sheets. Furthermore, these changes to the physical and chemical properties occur on exactly the same time scale, suggesting that they have a common origin. This discovery lends greater understanding to the formation of graphene oxide-based hydrogels, which could allow more flexibility and tunability in synthetic methods for graphene-like materials.

Simultaneous polymerization and crosslinking for the synthesis of molecular-level graphene oxide–polyacryl amide–CeOx composites

Synthesis of molecular-level multiple-component composites are particularly challenging due to the lack of direct bonding among different components. In this study, molecular-level graphene oxide (GO)–polyacryl amide (PAM)–CeOx composites were successfully synthesized, using the simultaneous polymerization and crosslinking strategy. Attenuated total reflection Fourier transform infrared (ATR-FTIR) and nuclear magnetic resonance (NMR) techniques confirmed that polyacryl amide (PAM) chains were successfully grafted onto the surface of GO. X-ray photoelectron spectroscopic (XPS) and X-ray diffraction (XRD) analyses further revealed the characteristic signals of cerium elements and CeO2 phase respectively. Scanning electron microscopy (SEM) showed that the surface morphology of the GO–PAM–CeOx composites was substantially thicker and rougher than those of the original GO. Further exploration of the reaction mechanism clearly demonstrate the existence of strong chelating interaction among PAM chains and Ce(IV) ions. In particular, the polymerization of acryl amide monomers and the crosslinking reaction between PAM and Ce(IV) or Ce(III) ions were realized simultaneously, leading to the final formation of molecular-level GO–PAM–CeOx composites. Moreover, the as-synthesized GO–PAM–CeOx composites were capable of effectively decomposing Rhodamine B under simulated sunlight, making it a potential candidate as a new photo catalyst. To sum up, this report demonstrates the potential utility of simultaneous polymerization and crosslinking method for the synthesis of other multiple-component composites at molecular-level.

Utilization of hollow kapok fiber for the fabrication of a pH-sensitive superabsorbent composite with improved gel strength and swelling properties

A pretreated kapok fiber (PKF) with a hollow tube structure was introduced into a poly(sodium acrylate) network by a simultaneous free-radical graft copolymerization and crosslinking reaction to fabricate a novel kapok fiber-g-poly(sodium acrylate) (PNaA/PKF) superabsorbent composite. The network characteristics and surface morphologies of the PNaA/PKF superabsorbent composite were investigated by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), as well as by determination of mechanical properties, swelling and stimuli responses to salts, and pH. The results showed that the incorporation of a specific amount of PKF not only improved the water absorption, but also the gel content and gel strength. The composite with 10 wt% PKF showed the best water absorption, gel content and gel strength. The swelling kinetics of the composite followed Schott's pseudo-second-order kinetics model, and the swelling rate constant was enhanced 2.63 fold after adding 10 wt% PKF. The swelling and deswelling behaviors in various saline and pH solutions revealed the stimuli-sensitivity of the PNaA/PKF composite to salt concentration, ionic charge and external pH, and a remarkable time-dependent swelling process with an overshooting characteristic was observed in pH 2 solutions.

Gamma ray-induced synthesis of hyaluronic acid/chondroitin sulfate-based hydrogels for biomedical applications

Hyaluronic acid (HA)/chondroitin sulfate (CS)/poly(acrylic acid) (PAAc) hydrogel systems were synthesized by gamma-ray irradiation without the use of additional initiators or crosslinking agents to achieve a biocompatible hydrogel system for skin tissue engineering. HA and CS derivatives with polymerizable residues were synthesized. Then, the hydrogels composed of glycosaminoglycans, HA, CS, and a synthetic ionic polymer, PAAc, were prepared using gamma-ray irradiation through simultaneous free radical copolymerization and crosslinking. The physicochemical properties of the HA/CS/PAAc hydrogels having various compositions were investigated to evaluate their feasibility as artificial skin substitutes. The gel fractions of the HA/CS/PAAc hydrogels increased in absorbed doses up to 15kGy, and they exhibited 91–93% gel fractions under 15kGy radiation. All of the HA/CS/PAAc hydrogels exhibited relatively high water contents of over 90% and reached an equilibrium swelling state within 24h. The enzymatic degradation kinetics of the HA/CS/PAAc hydrogels depended on both the concentration of the hyaluronidase solution and the ratio of HA/CS/PAAc. The in vitro drug release profiles of the HA/CS/PAAc hydrogels were significantly influenced by the interaction between the ionic groups in the hydrogels and the ionic drug molecules as well as the swelling of the hydrogels. From the cytotoxicity results of human keratinocyte (HaCaT) cells cultured with extracts of the HA/CS/PAAc hydrogels, all of the HA/CS/PAAc hydrogel samples tested showed relatively high cell viabilities of more than 82%, and did not induce any significant adverse effects on cell viability.

A Polymerizable Bioionic Liquid Based Nanogel: A New Nanocarrier for an Anticancer Drug

Nanogels (NGs) are considered as one of the most suitable nanocarrier matrices for drug, gene and protein delivery. There are many methods of synthesis of NGs but polymerizable bioionic liquids are not being applied so far for the synthesis of such nanocarriers. The synthesis of a stimuli‐responsive NG system having average hydrodynamic size of 41 ± 15 nm is reported here, obtained by the simultaneous polymerization and crosslinking of a polymerizable biobased ionic liquid. The NG thus obtained shows prolonged drug delivery for 5‐fluorouracil, an anticancer drug, at pH 1.2 (stomach pH) for 10 days at physiological human body temperature (37 °C). However, no substantial drug delivery is observed at pH 5 and 7.4. Such a prolonged drug release profilemakes the reported NG system a potential candidate in the formulation of a pH‐sensitive drug nanocarrier vehicle for in vivo delivery of stomach‐specific therapeutic agents. image

Simultaneous corneal crosslinking and surface ablation combined with phakic intraocular lens implantation for managing keratoconus.

To assess the efficacy and stability of simultaneous topography-guided photorefractive keratectomy (PRK) and crosslinking (Athens protocol) followed by phakic intraocular lens (IOL) implantation for managing keratoconus. Ain-Shams University, Cairo, Egypt. Prospective non-randomized study. All patients underwent topography-guided PRK followed immediately by collagen crosslinking (Athens protocol), 2-4 months later, eyes were implanted with either an iris claw or an angle-supported phakic IOL. Statistical analysis was performed with SigmaPlot software version 11.0 (Systat Software, Inc.). This study evaluated 22 eyes of 14 patients. Follow-up interval was at least 6 months. A Veriflex phakic IOL was implanted in 14 eyes (63.6 %), and a Cachet phakic IOL was implanted in 8 eyes (36.4 %). The mean preoperative keratometric reading (45.57 ± 1.51 D) was significantly reduced at 3 months and at 6 months after treatment (43.82 ± 1.98 D, P < 0.001). The mean spherical equivalent was significantly reduced from -9.08 ± 2.5 to -0.69 ± 0.67 D, P = <0.001. The mean UCVA improved from 1.24 ± 0.49 to 0.37 ± 0.08 logMAR. The mean corrected distance visual acuity (CDVA; logMAR) improved from 0.69 ± 0.3 preoperatively to 0.35 ± 0.01 postoperatively (P = <0.001). At last follow-up, all eyes could achieve CDVA of 0.3 or better. The difference between pre- and postoperative endothelial cell counts was not statistically significant. Combining phakic IOLs and the Athens protocol improved and stabilized visual performance in patients with keratoconus. These results justify a future, large-scale study with a longer follow-up.

Mechanical properties of tough hydrogels synthesized with a facile simultaneous radiation polymerization and cross-linking method

Radiation-induced polymerization and cross-linking method has been applied to hydrogel preparations for decades, but less attention has been paid to the mechanical properties of the hydrogels. In this work, we provide a systematic study on the mechanical properties of hydrogels synthesized with the simultaneous radiation polymerization and cross-linking method. The prepared polyacrylamide (PAAm) had very good mechanical properties, namely high compressive strengths (several to more than 10MPa), high tensile strengths (up to 260kPa), high fracture strains (up to 12) and high fracture energies (10–160J/m2). Absorbed dose and monomer concentration were the two important factors affecting the mechanical properties of the gels. The compressive strength and elastic modulus of the gels increased with increasing absorbed dose and monomer concentration, while the tensile strength, fracture strain and fracture energy of the gels decreased with increasing absorbed dose. The gels also showed excellent elastic recovery property, as indicated by the low stress–strain hysteresis ratios in cyclic tensile tests as well as the small loss factors measured with dynamic mechanical analysis (DMA).

Simultaneous crosslinking and cationization of cotton cellulose by using dialdehyde and choline chloride: comparison between the pad-dry-cure and microwave irradiation process

Simultaneous crosslinking and cationization of cotton cellulose were carried out by using two dialdehydes, glyoxal (GO) and glutaraldehyde (GA), along with choline chloride (ChCl). Two heating methods, conventional pad-dry-cure (PDC) and microwave irradiation, were investigated and compared. The results revealed that two aldehyde molecules reacted very differently in the presence of ChCl under two different heating methods. GO reacted predominantly with the cellulose molecule, stimulating the crosslinking reaction and consequently resulting in high wrinkle recovery angle (WRA) values regardless of the heating process. Contrarily, GA favored the reaction with ChCl, allowing high K/S values with acid dye under microwave irradiation. The crosslinked and cationized cotton cellulose was only obtained by treatment with GA and ChCl under the PDC process, resulting in high WRA and K/S values. Characteristics of the treated fabrics were also evaluated by Fourier transform infrared analysis, thermogravimetric analysis, scanning electron microscopy, water of imbibition, and tensile strength test. Additionally, the treatments with GA and ChCl also provided high antimicrobial properties of the cotton celluloses; thereby most bacteria reductions of the specimens were close or equal to 99.9 %. Therefore, economically viable yet ecofriendly crosslinking and cationization of cotton cellulose could be made by treatment with GA and ChCl.

Crosslinked fibrin gels for tissue engineering: two approaches to improve their properties.

Fibrin is a protein that can be used as an ideal scaffolding material to promote tissue regeneration. In order to enhance its physical properties in this study a natural crosslinker, genipin (GP), was employed with the aim to obtain a hydrogel with tuneable properties for tissue engineering applications. The fibrin gel was crosslinked by two different methods using four concentrations of GP to get a stable hydrogel network. Crosslinking density, mechanical properties, swelling, and enzymatic degradation of the hydrogels were tested for each GP content and method employed. The method I: Crosslinking after gel formation promotes a high crosslinking and retains the gel shape for long term whilst the method II: Simultaneous gel formation and crosslinking improves the mechanical properties of the gel. This study confirms the use of GP at different concentrations as a suitable crosslinker of fibrin that promotes the cellular viability of L929 for 21 days of in vitro culture.

Effect of titanium dioxide on chemical and molecular changes in PVC sidings during QUV accelerated weathering

Titanium dioxide (TiO2) is the most essential additive in polyvinyl chloride (PVC) matrixes used for outdoor applications. In this study, we primarily investigate the effect of TiO2 on the chemical and molecular changes in PVC sidings during QUV accelerated weathering. The results of this study show that carbonyl and polyene groups were generated on the surface of all of the specimens after 480 h of accelerated weathering but that loading TiO2 into PVC successfully inhibited the increase in the number of these oxidative groups over the entire exposure period compared to PVC without TiO2. In addition, a significant decrease in the number average molecular weight (Mn) and the formation of an insoluble gel were observed for PVC without TiO2 after accelerated weathering. However, the time required for the Mn to decline increased with the amount of TiO2 that was loaded into the PVC matrix, and no insoluble gel was observed during weathering. Furthermore, the crystallinity of PVC without TiO2 increased noticeably after 1920 h of accelerated weathering, whereas no significant change was observed in the crystallinity of PVC with TiO2. These results demonstrate that simultaneous chain scission and crosslinking reactions occurred in PVC without TiO2, whereas only chain scission occurred in PVC containing TiO2. In addition, the chain scission of PVC without TiO2 was initiated earlier than for PVC with TiO2, producing shorter and more mobile chains that underwent secondary crystallization. Accordingly, TiO2 acted as a UV absorber and a radiation screener such that the probability of chain scission was reduced for TiO2-loaded PVC sidings.

Thermosensitive Ionic Microgels via Surfactant-Free Emulsion Copolymerization and in Situ Quaternization Cross-Linking

A type of thermosensitive ionic microgel was successfully prepared via the simultaneous quaternized cross-linking reaction during the surfactant-free emulsion copolymerization of N-isopropylacrylamide (NIPAm) as the main monomer and 1-vinylimidazole or 4-vinylpyridine as the comonomer. 1,4-Dibromobutane and 1,6-dibromohexane were used as the halogenated compounds to quaternize the tertiary amine in the comonomer, leading to the formation of a cross-linking network and thermosensitive ionic microgels. The sizes, morphologies, and properties of the obtained ionic microgels were systematically investigated by using transmission electron microscopy (TEM), dynamic and static light scattering (DLS and SLS), electrophoretic light scattering (ELS), thermogravimetric analyses (TGA), and UV-visible spectroscopy. The obtained ionic microgels were spherical in shape with narrow size distribution. These ionic microgels exhibited thermosensitive behavior and a unique feature of poly(ionic liquid) in aqueous solutions, of which the counteranions of the microgels could be changed by anion exchange reaction with BF4K or lithium trifluoromethyl sulfonate (PFM-Li). After the anion exchange reaction, the ionic microgels were stable in aqueous solution and could be well dispersed in the solvents with different polarities, depending on the type of counteranion. The sizes and thermosensitive behavior of the ionic microgels could be well tuned by controlling the quaternization extent, the type of comonomer, halogenated compounds, and counteranions. The ionic microgels showed superior swelling properties in aqueous solution. Furthermore, these ionic microgels also showed capabilities to encapsulate and release the anionic dyes, like methyl orange, in aqueous solutions.

Crosslinked poly (ether ether ketone) hydroxide exchange membranes with improved conductivity

Crosslinked poly (ether ether ketone) (PEEK) hydroxide exchange membranes are prepared using bi-functional cyclic ammonium, 1,4-diazabicyclo [2,2,2] octane (DABCO), as simultaneous quaternization and crosslinking reagent. Hydroxide conductivity and ion mobility are evaluated as a function of ion concentration, which integrates the counteracting effects of the hydroxide ion amount and crosslinking degree. With the increase of ion concentration, effective mobility of hydroxide ion increases to a high level and then levels off or slightly goes down, suggesting a balance existed between ion concentration and mobility in the crosslinked membranes. As a result, hydroxide conductivity increases rapidly to a high stable level, indicating the applicable range of ion concentration (up to 1.0molL−1) for improving hydroxide conductivity. The crosslinked membranes exhibit high hydroxide conductivity of 33.4mScm−1 at 25°C and low swelling ratio of 48.2% at 60°C. Thermal stability (Tonset: 176°C) of the crosslinked membranes is better as compared with the non-crosslinked (Tonset: 165°C) and trimethylamine quaternized PEEK membranes.

Advantages of Orthogonal Folding of Single Polymer Chains to Soft Nanoparticles

We investigate, by means of computer simulations, the formation of soft nanoparticles by irreversible intramolecular cross-linking of homofunctional polymer precursors in good solvent. Simulations reveal that the early and intermediate stages of the cross-linking process are dominated by bonding at short contour distances. Because of the initial self-avoiding character of the precursor, bonding at long contour distances, which is the efficient mechanism for global compactation, is a rare event that essentially occurs in the late stage of cross-linking. Thus, irreversible cross-linking of precursors with identical molecular weight and linker fraction produces both compact and sparse objects. This is confirmed by a detailed analysis of the size and shape distribution of the fully cross-linked nanoparticles. We also investigate intramolecular cross-linking of heterofunctional polymers with two species of orthogonal linkers, bonding between distinct species being forbidden. It is found that simultaneous cross-linking of both species and sequential cross-linking (activation of one species after full cross-linking of the other) lead to the same structural properties for the resulting nanoparticles. The heterofunctional nanoparticles are on average smaller and more spherical than the homofunctional counterparts, though still a significant fraction of sparse objects is found. The simulation results are compared with results from SEC/MALLS and SAXS experiments in real polymeric nanoparticles.

Transepithelial Photorefractive Keratectomy with Crosslinking for Keratoconus

Purpose:To analyse visual, refractive and topographic outcomes of combining transepithelial photorefractive keratectomy (tPRK) with simultaneous corneal crosslinking for the visual rehabilitation of contact lens intolerant keratoconus patients.Methods:Patients with topographically significant keratoconus, limited corrected vision and intolerant of contact lenses were prospectively recruited, subject to ethical approval and consent. All patients underwent single step aspheric tPRK and sequential crosslinking. Preoperative vision, refraction, corneal topography and wavefront were assessed, with postoperative assessment at 1, 3, 6, and 12 months.Results:22 eyes of 14 patients were included in the pilot study. Mean age was 32 years (SD 6.8, range 24 to 43). Mean preoperative unaided vision was 1.39 LogMAR (SD 0.5) best corrected 0.31 LogMAR (SD 0.2). Mean preoperative spherical equivalent was -2.74 Diopters (D) (SD 4.1 range -12.25 to +7.75), and mean cylinder -2.9 D (SD 1.2, range 0 to -5.5). Mean central corneal thickness was 461um (SD 29, range 411 to 516). Vision improved postoperatively; unaided 0.32 LogMAR (SD 0.4), best corrected 0.11 (SD 0.13) (P=<0.005). Mean postoperative cylinder was -1.4D (SD1.2), significantly reduced (p<0.005). Maximum keratometry (Kmax) was stable throughout postoperative follow up. (p<0.05).Conclusions:Non topographic transepithelial PRK with simultaneous crosslinking improves vision, and may offer an alternative to keratoplasty in contact lens intolerant keratoconus. Further comparative studies to topographic PRK techniques are indicated.

Antitumor Immunity: Easy as 1, 2, 3 with Monoclonal Bispecific Trifunctional Antibodies?

Monoclonal antibodies occupy an increasing niche in the arsenal available to treat cancer. Several developments have rendered this the fastest growing sector in the pharmaceutical industry. Traditionally, antibodies were developed to block key signaling molecules implicated in tumor progression. However, antibodies also recruit additional immune effector mechanisms against tumors, a property that may be exploited for clinical benefit. Bispecific antibodies represent one such strategy in which elements derived from two monoclonal antibodies are incorporated into a single molecular species. Commonly, the bispecific approach is used to achieve simultaneous cross-linking of CD3 and a tumor antigen such as epithelial cell adhesion molecule (EpCAM), thereby recruiting T-cell activation to the tumor cell surface. A further sophistication involves the engineering of trifunctional derivatives such as the clinically approved agent, catumaxomab. Catumaxomab has antigen-binding arms that engage CD3 and EpCAM and a constant domain that recruits Fc receptor-bearing cells, notably monocytes, dendritic cells, and natural killer cells. Owing to this triangular binding capability, catumaxomab can activate both innate and adaptive immune effector mechanisms in addition to promoting immunologic memory. Recent data indicate that this agent can also promote immunogenic cell death, particularly when used in combination with selected chemotherapeutic agents such as oxaliplatin.

Effects of simultaneous chemical cross-linking and physical filling on separation performances of PU membranes

The novel modified polyurethane (PU) membranes were prepared by β-cyclodextrin (CD) cross-linking and SiO2/carbon fiber filler, simultaneously. The structures, thermal stabilities, morphologies, and surface properties were characterized by FTIR, TGA, SEM, and contact angle. The results showed that the addition of inorganic particles increased the thermal stabilities of PU membranes. The modified PU membranes possessed more hydrophobic surfaces than pure PU. In the swelling investigation, PU and its modified membranes were swelled gradually with increasing phenol content in the mixture. The membranes modified by CD cross-linking (PUCD) demonstrated the highest swelling degree. Pervaporation (PV) performances were investigated in the separation of phenol from water. Three kinds of modified membranes obtained better permeability and selectivity than PU membranes. With the feed mixture of 0.5 wt% phenol at 60 °C, the modified PU membrane by CD cross-linking and SiO2 filler (PUCD-S) obtained the total flux of 5.92 kg μm m−2 h−1 which was above doubled that of PU (2.90 kg μm m−2 h−1). The modified PU membrane by CD cross-linking and carbon fiber filling (PUCD-C) obtained the separation factor of 51.31 which was nearly tripled that of PU (17.72). The PUCD membranes showed both better permeability and selectivity than the pure PU membranes. The increased phenol content induced an increased separation factor of PUCD and PU, but a decreased selectivity of PUCD-S and PUCD-C. The methods of CD cross-linking and inorganic particle filling were effective to develop the overall separation performances, greatly.

Radio-synthesized polyacrylamide hydrogels for proteins release

The use of hydrogels for biomedical purposes has been extensively investigated. Pharmaceutical proteins correspond to highly active substances which may be applied for distinct purposes. This work concerns the development of radio-synthesized hydrogel for protein release, using papain and bovine serum albumin as model proteins. The polymer was solubilized (1% w/v) in water and lyophilized. The proteins were incorporated into the lyophilized polymer and the hydrogels were produced by simultaneous crosslinking and sterilization using γ-radiation under frozen conditions. The produced systems were characterized in terms of swelling degree, gel fraction, crosslinking density and evaluated according to protein release, bioactivity and cytotoxicity. The hydrogels developed presented different properties as a function of polymer concentration and the optimized results were found for the samples containing 4–5% (w/v) polyacrylamide. Protein release was controlled by the electrostatic affinity of acrylic moieties and proteins. This selection was based on the release of the proteins during the experiment period (up to 50h), maintenance of enzyme activity and the nanostructure developed. The system was suitable for protein loading and release and according to the cytotoxic assay it was also adequate for biomedical purposes, however this method was not able to generate a matrix with controlled pore sizes.

Catalyst Coated PBI Membrane High Temperature Assemblies

A route has been developed to stabilise a polybenzimidazole gel membrane formed in polyphosphoric acid by simultaneous cross-linking. With increasing degrees of cross-linking the mechanical properties of the high acid content PBI membranes are significantly improved, while the phosphoric acid content and the membrane conductivity are not greatly affected. PBI/H3PO4 membranes are generally integrated into an assembly using gas diffusion electrodes. In the present work, cross-linked PBI membranes have been used as substrates for catalyst coated membrane preparation using a Pt/C catalyst transferred by decal to the membrane surfaces. The final membrane electrode assemblies have been characterized for their high temperature performance and durability.

Chemically Reduced Graphene Oxide with Crosslinked Shell Showing Enhanced Environmental Stability Using Thiol-grafted Pluronic

Abstract Soluble RGO/Plu–S–S assembly with crosslinked Pluronic shell structure was formulated through noncovalent interaction between Plu–SH and RGO plates and simultaneous crosslinking of Plu–SH on RGO plates. While other RGO/aliphatic polymer assemblies show limited solubility only in aqueous media, RGO/Plu–S–S assembly showed enhanced environmental stability and organic solubility with the help of crosslinked shell structure.