Fast Curing Research Articles

A novel and feasible approach for one-pack flame-retardant epoxy resin with long pot life and fast curing

Liquid epoxy resins (EP), curing agents, as well as other additives such as flame retardants are preferred to be formulated as one-pack materials rather than being mixed just prior to their applications. Therefore, they suffer premature curing with increasing of viscosity during storing and operating. To address the above challenging problem, we designed and synthesized a novel latent flame-retardant curing agent named 1-(diphenylphosphinyl)-1H-imidazole oxide (DPPIO) for EP, which was proved exhibiting not only long pot life during storing and fast curing as operating, but also excellent flame retardance after curing. It was observed from dynamic rheometry that, DPPIO/EP kept stable near room temperature for a long time but quickly gelated within only 6.5 min at 150 °C. With only 15 wt% addition of DPPIO, the limiting oxygen index (LOI) of the cured sample increased to 38.0% from 21.0% of the contrast sample, and UL-94 V-0 rating at 1.6 mm thickness was successfully achieved. Peak of heat release rate (PHRR) and total heat release (THR) obtained from cone calorimetry further certified excellent flame retardance of DPPIO/EP. Another typical flame-retardant group with different chemical environment was designed for modifying imidazole to obtain a derivative named diphenyl 1H-imidazol-1-ylphosphonate (DPIPP) in the same way. It was verified that DPIPP/EP showed acceptable latent curing efficiency and satisfactory flame retardance as DPPIO/EP did. Therefore, it’s a generally effective and facile approach to develop latent flame-retardant curing agents for EP by modifying imidazole with appropriate flame-retardant groups. Taking advantage of the features, these one-pack flame-retardant epoxy materials can bring more chances for widespread applications.

Environmental Factors Affecting the Strength Characteristics of Modified Resin Mortars

Resin concretes are composites in which a cement binder has been completely replaced by a synthetic resin. These materials are a good choice for the construction industry, especially in solutions requiring high strength, fast curing and durability. Polymer mortars are mainly used for the manufacture of industrial floors and prefabricated products such as tanks for aggressive chemicals, sewage pipes, or road and bridge drainage systems, as well as for the repair of damaged concrete structures. In all these applications, the strength and high chemical resistance of the applied material solutions are of key importance. It is particularly crucial to obtain information on how resin composites behave when exposed to aggressive agents over extended periods of time. It is also very important to use waste materials in order to obtain resin composites, as these activities are very well inscribed in the idea of environmental protection and meet the criteria of sustainable construction. The mortars described in this article meet the above principles. The article presents how the compressive strength of glycolyzate-modified epoxy mortars, obtained with the use of poly(ethylene terephthalate), changes after they are immersed in 10% sodium chloride solution. Sodium chloride solution was chosen due to the prospective applicability of the tested composites as repair materials used for e.g. bridges or overpasses that are exposed to this salt solution in wintertime. Changes in the properties of the composite samples were monitored over the period of one year. Statistical analysis of the test results was carried out with the use of Statistica programme. The module available in the mentioned program called Nonparametric Statistics - Comparing multiple independent samples made it possible to check the monitoring times during which the compressive strength values differed significantly. The obtained results allowed for determining the equation of the function approximating the course of changes in mortar properties. The designated parameters of regression equations can be used to project the properties of composites.

TTT‐diagram for epoxy film adhesives using quasi‐isothermal scans with initial fast ramps

ABSTRACTThe characterization of film adhesives is challenging because they required freezer storage, contain an inseparable filler—thermoplastic knit or fiber‐reinforcement, and are heat activated systems with a pre‐cure and unknown chemistry. A testing protocol that eliminates these sources of error is proposed. This study presents a method to generate time–temperature‐transformation (TTT) diagrams of epoxy film adhesives via differential scanning calorimetry (DSC). Non‐isothermal and isothermal DSC scans are used to capture the reaction and the glass transition temperature. The use of an initial fast ramp—up to 500 K/min—in the isothermal scans is explored for the first time. This technique shows the potential to produce a quasi‐isothermal cycle, eliminating the loss of data in the initial stage of the reaction. The total heat released, the activation energy, and the fractional kinetic parameter, are estimated via model‐free methods. The Kamal–Sourour model and the formal kinetic model are fit to model the rate of cure. The simplest model that accurately captures the reaction, a parallel two‐step model, A , is outlined. The glass transition temperature is modeled via DiBenedetto's equation to include the diffusion‐controlled mechanism. The TTT‐diagrams of two commercial adhesives, DA 408 and DA 409, are shown with an analysis of processing optimization. The use of quasi‐isothermal scans with initial fast ramps combined with the correction for filler, moisture, and pre‐curing history can be applied to characterize fast curing thermosets, complex B‐stage resins, and thermosetting composites. The modeling results can also be used in numerical studies of residual stresses and dimensional stability in the manufacturing of thermosetting composites. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45791.

Fast Curing Bio-Based Phenolic Resins via Lignin Demethylated under Mild Reaction Condition.

Demethylation technique has been used to enhance lignin reactivity for preparation of phenolic resins. However, the demethylation efficiency and the demethylated lignin (DL) reactivity were still unsatisfactory. To improve the demethylation efficiency, alkali lignin was demethylated under different mild conditions using sodium sulfite as a catalyst. Lignin and DL were characterized by 1H-NMR (nuclear magnetic resonance) and Fourier transform infrared (FT-IR) spectroscopy to determine the demethylation mechanism. With the demethylation of lignin, the methoxyl group content decreased from 1.93 m mol/g to 1.09 m mol/g, and the phenolic hydroxyl group content increased from 0.56 m mol/g to 0.82 m mol/g. These results revealed that methoxyl groups were attacked by SO32−, and some methoxyl groups were converted to phenolic hydroxyl groups by a nucleophilic substitution reaction, generating DL with high reactivity. The chemical properties of lignin-based phenolic resins were studied by 13C-NMR and FT-IR spectroscopy, and their physical properties were also investigated. The results indicated that lignin-based phenolic resins exhibited faster curing rate and shorter gel time. In addition, the bonding strength increased from 0.92 MPa to 1.07 MPa, and the formaldehyde emission decreased from 0.58 mg/L to 0.22 mg/L after lignin demethylated at the optimum condition.

Development of a thiol‐ene based screening platform for enzyme immobilization demonstrated using horseradish peroxidase

Efficient immobilization of enzymes on support surfaces requires an exact match between the surface chemistry and the specific enzyme. A successful match would normally be identified through time consuming screening of conventional resins in multiple experiments testing individual immobilization strategies. In this study we present a versatile strategy that largely expands the number of possible surface functionalities for enzyme immobilization in a single, generic platform. The combination of many individual surface chemistries and thus immobilization methods in one modular system permits faster and more efficient screening, which we believe will result in a higher chance of discovery of optimal surface/enzyme interactions. The proposed system consists of a thiol-functional microplate prepared through fast photochemical curing of an off-stoichiometric thiol-ene (OSTE) mixture. Surface functionalization by thiol-ene chemistry (TEC) resulted in the formation of a functional monolayer in each well, whereas, polymer surface grafts were introduced through surface chain transfer free radical polymerization (SCT-FRP). Enzyme immobilization on the modified surfaces was evaluated by using a rhodamine labeled horseradish peroxidase (Rho-HRP) as a model enzyme, and the amount of immobilized enzyme was qualitatively assessed by fluorescence intensity (FI) measurements. Subsequently, Rho-HRP activity was measured directly on the surface. The broad range of utilized surface chemistries permits direct correlation of enzymatic activity to the surface functionality and improves the determination of promising enzyme-surface candidates. The results underline the high potential of this system as a screening platform for synergistic immobilization of enzymes onto thiol-ene polymer surfaces. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1267-1277, 2017.

Urea-formaldehyde resins: production, application, and testing

Urea-formaldehyde (UF) resin, one of the most important formaldehyde resin adhesives, is a polymeric condensation product of formaldehyde with urea, and being widely used for the manufacture of wood-based composite panels, such as plywood, particleboard, and fiberboard. In spite of its benefits such as fast curing, good performance in the panels (colorless), and lower cost; formaldehyde emission (FE) originated from either UF resin itself or composite products bonded by UF resins is considered a critical drawback as it affects human health particularly in indoor environment. In order to reduce the FE, lowering formaldehyde/urea (F/U) mole ratio in the synthesis of the UF resin was done. In this study, synthesis of UF resins was carried out following the conventional alkaline-acid two-step reaction with a second addition of urea, resulting in F/U mole ratio around 1.0, namely 0.95; 1.05, and 1.15. The UF resins produced were used as binder for particleboard making. The board was manufactured in the laboratory using shaving type particle of Gmelina wood, 8% UF resin based on oven dry particle, and 1% NH4Cl (20%wt) as hardener for the resin. The target of the thickness was 10 mm and the dimension was 25 cm x 25 cm. The resulted particleboard then was evaluated the physical and the mechanical properties by Japanese Industrial Standard (JIS) A 5908 (2003). Further, the resulted particleboard also was used for the mice cage’s wall in order to mimic the real living environment. After four weeks exposure in the cages, the mice then were evaluated their mucous organs as well as their blood. The experiment results were as follows: 1) It was possible to synthesis UF resins with low F/U mole ratio; 2) However, the particleboard bonded UF resins with low F/U mole ratio showed poor properties, particularly on the thickness swelling and modulus of elasticity; 3) There was no significant differences among the mucous organs of the mice after a month exposure FE originated from cages wall using histopathology assessment.

The CTX-M-14 plasmid pHK01 encodes novel small RNAs and influences host growth and motility.

The dissemination of extended-spectrum β-lactamases (ESBLs) genes among bacteria is commonly achieved by plasmid conjugation. In the last decade, the CTX-M type enzyme was the most widespread and prevalent ESBLs in the world. In Hong Kong and mainland China, among the commonly found CTX-M-carrying plasmids were pHK01 and pHK01-like plasmids, which belong to incompatibility group FII (IncFII). In this work, we studied the physiological effect caused by the pHK01 plasmid in bacterial host Escherichia coli J53. The plasmid did not affect cell growth of the host but reduced their motility. The reduction of host motility was attributed to downregulation of genes that encode the flagellar system. We also identified several plasmid-encoded sRNAs, and showed that the overexpression of one of them, AS-traI, in the presence of pHK01 plasmid shortened the lag phase of host growth. In addition to the study of pHK01 in bacteria, we also developed a fast and incompatibility group-specific curing method using countertranscribed RNA, which could be of general usage for studying plasmid-host interaction in clinical aspects.

Abstract 3214: Systematic drug repurposing for faster cures of pediatric cancer identifies that Digoxin prolongs survival in a PDOX model of group 4 medulloblastoma

Abstract Background: Medulloblastoma (MB) is the most common malignant brain tumor of childhood. While the current standard care for MB leads to long term survival in approximately 75 % of patients; recurrent and refractory MB continues to have dismal outcomes. In addition, long term survivors face significant treatment-related sequelae especially poor neurocognitive outcomes. Drug repositioning for known drugs is a promising potential strategy not only for drug discovery but also for accelerated translation into the clinical setting. To systematically explore thousands of known drugs available, we integrated computational biology and empirical biology methods to find old drugs for new indications in MB. Results: A non-parametric, bootstrapping based simulated annealing (NPBSA) algorithm was employed to identify driver signaling pathways for over 1,800 patients with Group 3 and Group 4 MB through an integrative analysis on their mRNA expression, DNA-copy number, DNA-methylation and DNA-seq profiles. Then, drug functional networks were constructed based on gene expression profiles under drug treatment as well as chemical structures and were clustered into drug modules with potential mechanisms of action. By evaluating targeted effects of 1,309 drugs from connectivity map database within each drug module in driver signaling pathways, we identified a group of known cardiac glycosides that top ranked among the total drug candidates for the Group 3 and 4 MB subtypes. In addition to traditional chemotherapeutic agents, members of the cardiac aminoglycoside family were repeatedly identified as potential therapeutic agents for MB. These findings were validated in multiple MB-derived cell lines which showed high rates of growth inhibition by cardiac aminoglycosides compared to controls. To evaluate if this growth inhibition in vitro correlated to prolonged survival in vivo, an extensively characterized patient-derived orthotopic-xenograft (PDOX) model of Group 4 MB (ICb-1078MB) was treated with digoxin (2 mg/kg i.p.) for 2 cycles of 14 days. Digoxin treatment significantly prolonged survival to 113 days from a median of 92 days in untreated controls (p=0.001). Histological evaluation of recurrent tumors following digoxin treatment demonstrated changes in the pattern of tumor spread, vascularity and necrosis compared to untreated controls. Conclusions: Leveraging big data in the domains of pharmacogenomics and the notion of drug functional networks and driver signaling pathways represents a powerful tool to repurpose known drugs for new indications in pediatric cancers. Using this integrative biology approach, we identified the cardiac aminoglycosides family generally and Digoxin, specifically, as potential novel agents in the treatment of pediatric medulloblastoma Citation Format: Lei Huang, Sarah G. Injac, Hong Zhao, Qi Lin, Mari Kogiso, Chris T. Man, Xiao-Nan Li, Ching C. Lau, Stephen T. Wong. Systematic drug repurposing for faster cures of pediatric cancer identifies that Digoxin prolongs survival in a PDOX model of group 4 medulloblastoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 3214. doi:10.1158/1538-7445.AM2017-3214

Abstract 1627: Enhancement of anti-cancer immunity by OMX, a novel oxygen carrier immunotherapeutic that ameliorates the hypoxic tumor microenvironment

Abstract Hypoxia is a hallmark of cancer and a driver of tumor progression and poor patient outcomes. By generating an immunosuppressive tumor microenvironment that limits cytotoxic T lymphocyte (CTL) infiltration and activation, hypoxia limits the effectiveness of cancer immunotherapy and thus promotes tumor cell evasion of the host immune response. Omniox has developed a first-in-class anti-cancer immunotherapeutic, OMX, specifically designed to reverse tumor hypoxia to enhance cancer immunotherapy efficacy. In preclinical models, we have demonstrated that OMX accumulates in rodent subcutaneous and orthotopic tumors, as well as spontaneous canine melanomas and brain tumors, resulting in significant tumor hypoxia reduction.Here, using multiple subcutaneous syngeneic mouse tumor models (MC38, CT26, 4T1), we assessed OMX effects on intratumoral CTLs and immunosuppressive regulatory T cells (Treg), as well as the anti-tumor potential of OMX as a single agent and in combination with established immunotherapies. Using quantitative immunohistochemistry, we confirmed reports that hypoxic tumor areas are devoid of CTLs. Accordingly, by flow cytometry we observed a negative correlation between tumor hypoxia and CTL infiltration. While OMX single agent treatment did not affect the overall CD45-positive leukocyte population, Treg cells were selectively depleted and the CTL:Treg ratio was substantially increased, suggesting that OMX induced a shift towards immunosensitization. Consistent with this finding, we observed OMX single agent anti-tumor efficacy in MC38 colon tumors. Impressively, anti-tumor effects of OMX single agent were equivalent to that of a single treatment of the checkpoint inhibitor anti-CTLA4. We next assessed whether OMX would enhance the efficacy of checkpoint inhibitors when used in combination. In CT26 colon tumors, OMX exhibited combination anti-tumor activity with anti-CTLA4, giving rise to faster cures and a greater number of complete and durable responders compared to anti-CTLA4 alone. Of note, this enhanced response was observed for both early-stage and late-stage CT26 tumors. In 4T1 breast tumors, known to be insensitive to checkpoint inhibitors, treatment of early-stage (~60mm3) tumors with combination OMX and anti-PD1 resulted in a 27% response rate, compared to a 0% response rate to anti-PD1 alone. Taken together, our data suggest that OMX, by delivering oxygen to hypoxic tumor areas, induces a microenvironmental change from an immunosuppressive to an immunopermissive state. Given that OMX is well-tolerated in both small and large animals, and that its mechanism of action is upstream of numerous major immunosuppressive pathways, OMX holds great clinical potential to synergize with multiple immunotherapeutic agents to enhance tumor control by restoring anti-cancer immune responses in cancer patients. Citation Format: Kevin G. Leong, Yuqiong Pan, Jonathan A. Winger, Stephen P. Cary, Natacha Le Moan, Ana Krtolica. Enhancement of anti-cancer immunity by OMX, a novel oxygen carrier immunotherapeutic that ameliorates the hypoxic tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1627. doi:10.1158/1538-7445.AM2017-1627

Improvement of corrosion properties of porous alloy supports for solid oxide fuel cells

The development of protective coatings for porous metal supports is critical for sufficient life time for the fuel cells by enabling improved oxidation resistance, reduced chromium evaporation, and increased conductivity of the protective oxide scale. The oxidation of coated and non-coated substrates has been compared, and shows that it is possible to increase the oxidation resistance at 600 °C in air by a factor of 10 and in wet hydrogen by a factor of 1000, after vacuum coating of the porous metal supports by infiltration of a lanthanum–manganese–cobalt solution and fast curing in air at 900 °C. Chromium evaporation is also lowered by a factor of 10 in air at 600 °C. The experiments on pre-coated porous metal supports verify that the coating is well suited to use for metal supported fuel cells prepared by a low temperature fabrication route (below 1100 °C). An alternative coating procedure for coating of the metal supports after co-sintering of the anode and electrolyte has also been investigated and is well suited for the high-temperature fabrication route. For the high temperature fabrication route, the oxidation tests at 600 °C for 500 h in air and 100 h in wet hydrogen showed that post-coating is better than the pre-coating approach since the cell sintering steps has a detrimental effect on the pre-coated samples.

P11.08 Systematic drug repurposing for faster cures of pediatric cancer identifies that Digoxin prolongs survival in a PDOX model of group 4 medulloblastoma

Abstract Background: Medulloblastoma (MB) is the most common malignant brain tumor of childhood. While the current standard care for MB leads to long term survival in approximately 75 % of patients; recurrent and refractory MB continues to have dismal outcomes. In addition, long term survivors face significant treatment-related sequelae especially poor neurocognitive outcomes. Drug repositioning for known drugs is a promising potential strategy not only for drug discovery but also for accelerated translation into the clinical setting. To systematically explore thousands of known drugs available, we integrated computational biology and empirical biology methods to find old drugs for new indications in MB. Results: A non-parametric, bootstrapping based simulated annealing (NPBSA) algorithm was employed to identify driver signaling pathways for over 1,800 patients with Group 3 and Group 4 MB through an integrative analysis on their mRNA expression, DNA-copy number, DNA-methylation and DNA-seq profiles. Then, drug functional networks were constructed based on gene expression profiles under drug treatment as well as chemical structures and were clustered into drug modules with potential mechanisms of action. By evaluating targeted effects of 1,309 drugs from connectivity map database within each drug module in driver signaling pathways, we identified a group of known cardiac glycosides that top ranked among the total drug candidates for the Group 3 and 4 MB subtypes. In addition to traditional chemotherapeutic agents, members of the cardiac aminoglycoside family were repeatedly identified as potential therapeutic agents for MB. These findings were validated in multiple MB-derived cell lines which showed high rates of growth inhibition by cardiac aminoglycosides compared to controls. To evaluate if this growth inhibition in vitro correlated to prolonged survival in vivo, an extensively characterized patient-derived orthotopic-xenograft (PDOX) model of Group 4 MB (ICb-1078MB) was treated with digoxin (2 mg/kg i.p.) for 2 cycles of 14 days. Digoxin treatment significantly prolonged survival to 113 days from a median of 92 days in untreated controls (p=0.001). Histological evaluation of recurrent tumors following digoxin treatment demonstrated changes in the pattern of tumor spread, vascularity and necrosis compared to untreated controls. Conclusions: Leveraging big data in the domains of pharmacogenomics and the notion of drug functional networks and driver signaling pathways represents a powerful tool to repurpose known drugs for new indications in pediatric cancers. Using this integrative biology approach, we identified the cardiac aminoglycosides family generally and Digoxin, specifically, as potential novel agents in the treatment of pediatric medulloblastoma.

Investigation of foaming cell development for epoxy resin with blowing and curing agent by rheological properties

The effects of the curing and blowing agent concentration in an epoxy resin were investigated using rheological, mechanical, and optical methods. The curing time from the time sweep test decreased with increasing amount of curing agent at the fixed blowing agent concentration. On the other hand, with increasing blowing agent at a fixed curing agent concentration, the curing time showed a local minimum value. Minimization of the curing time is very useful for reducing the processing time. Axial normal forces as a function of time showed a relationship between the contraction force by the curing process and the expansion force by foaming process. From the axial normal force measurements, it could be categorized quantitatively into three parts: the curing dominant region (negative axial normal force development), transition region, and the foaming dominant region (positive axial normal force development). At the transition region, the axial normal force development was delayed because the foaming process was disturbed by the contraction. Mechanical and structural analysis were conducted for the fully cured and foamed epoxy resin. The completely developed epoxy foams with the high curing agent concentration become brittle. On the other hand, they contained well-distributed unit cell foams inside. This is because the fast curing process interrupts the coalescence of the closed foams. Overall, the optimal curing and blowing agent concentration for the epoxy resin could be determined from rheological analysis during the process and mechanical and structural analysis for fully cured and foamed epoxy resin.

Degree of cure of epoxy/acrylic photopolymers: Characterization with raman spectroscopy and a modified phenomenological model

This study characterizes the degree of cure c, of a two‐part epoxy/acrylic photopolymer used in stereolithography, SLA. The use of solid free form fabrication has added a whole new list of thermosets with a chemical reaction—curing reaction—targeted for these specific manufacturing processes. The studied thermosetting system exhibits a fast curing reaction triggered by a UV‐light source. An innovative stepwise method to quantify the degree of cure using Raman spectroscopy is reported. This method abates the Raman noise and compensates for the weak signal of fast measurements. The Raman data processing algorithm BEADS was implemented. The technique presented here was capable of following the degree of cure of the individual components of the photopolymer. Based on the epoxy/acrylic monomers concentration (75%/25%), the degree of cure for the whole system was quantified. The experimental results were modeled using a modified phenomenological kinetics equation. This model includes the dependency of the rate of cure on the light intensity, and cure state. Based on the analysis reported here, the proposed model accurately fits the initiation, propagation, and termination phases of the cure cycle. The technique and methods presented here can potentially be integrated to in situ process monitoring with instant parameter feedback, and numerical modeling of residual stresses in additive manufacturing of thermosets. POLYM. ENG. SCI., 58:228–237, 2018. © 2017 Society of Plastics Engineers

CALCULATION OF TIMES AND TEMPERATURES FOR PRESS VULCANIZATION OF THICK RUBBER PADS

ABSTRACT Rubber manufacturers need simple rules to enable them to find the correct cure time and temperature for thick articles. To this end finite element analysis, controlled by Python scripting, has been used to calculate press times that meet specifications for adequate cure for uniaxial heat flow through molded rubber pads over a range of thicknesses. Three press temperatures, the effect of first preheating the rubber, and the rate of cooling were investigated. A low press temperature, preheating of the rubber, and fast cooling were required to achieve a reasonably even state of cure through thick moldings. The heat of vulcanization was included in some of the models. Its effect was small. Unified plots of the simulation results for five commercial rubber compounds are presented, and simple equations are provided to enable the cure time at any cure temperature to be estimated. The applicability of the results to fast cures of thin sections is discussed.

Manufacturing gluing-in-rods under low temperatures and with shorter process times using induction and resistive heating

This paper summarizes joint research efforts of the University of Kassel and Fraunhofer IFAM, focusing on resistive and inductive heating as techniques to achieve fast curing in the particular context of tests on glued-in rods, as performed in the last 2 years. In different series of experiments, conducted on metallic bars glued into timber, the difficulties practitioners face with regard to temperature control are described. In a further set of experiments, induction is combined with a pre-applicable structural adhesive (PASA); it is shown how an innovative combination of PASA with induction heating leads to a process of gluing G-FRP rods into timber that substantially gains in terms of process quality and time. In the final series, in which a 1 K epoxy is mixed with metallic particles that exhibit a Curie temperature adapted to the curing temperature of the adhesive, we show how the induction process can be run without any outside control, leading to a technical solution adapted to practitioners.

Co-Curing of CFRP-Steel Hybrid Joints Using the Vacuum Assisted Resin Infusion Process

This study focuses on the one-step co-curing process of carbon fiber reinforced plastics (CFRP) joined with a steel plate to form a hybrid structure. In this process CFRP laminate and bond to the metal are realized simultaneously by resin infusion, such that the same resin serves for both infusion and adhesion. For comparison, the commonly applied two-step process of adhesive bonding is studied. In this case, the CFRP laminate is fabricated in a first stage through resin infusion of Non Crimp Fabric (NCF) and joined to the steel plate in a further step through adhesive bonding. For this purpose, the commercially available epoxy-based Betamate 1620 is applied. CFRP laminates were fabricated using two different resin systems, namely the epoxy (EP)-based RTM6 and a newly developed fast curing polyurethane (PU) resin. Results show comparable mechanical performance of the PU and EP based CFRP laminates. The strength of the bond of the co-cured samples was in the same order as the samples adhesively bonded with the PU resin and the structural adhesive. The assembly adhesive with higher ductility showed a weaker performance compared to the other tests. It could be shown that the surface roughness had the highest impact on the joint performance under the investigated conditions.

Surge in Philanthropy Fuels Cancer Research.

Philanthropy could lead to faster cures by funding riskier research-projects more likely to fail but with potentially high impact-and promoting better teamwork among researchers. However, researchers and fundraisers say that it should augment, not replace, government funding.

Advancing the manufacture of complex geometry GFRC for today's building envelopes

Advancing the manufacture of complex geometry GFRC for today's building envelopes

Advancing the manufacture of complex geometry GFRC for today's building envelopes

Advancing the manufacture of complex geometry GFRC for today's building envelopes

Drying time and post-harvest quality of onion bulbs submitted to artificial curing

ABSTRACT After harvest, onion bulbs are submitted to curing, whose objective is to provide loss of moisture in leaves and drying of outer layers (peel) of bulbs, reaching attractive external coloration and reduction in the intensity of rottenness. The objective of this study was to use an air treatment unit (ATU) - known as heat pump - as an alternative drying method, and to evaluate drying time and preservation of the chemical and physical characteristics. The experiment was carried out in a complete random design with ten replicates and three treatments, which were the following: T1- (control) natural curing in shed; (2) T2- (aeration with air artificially heated by propane burning); and (3) T3- (aeration with artificially dehydrated and heated air using ATU). Curing completion time, relative water content (RWC) of the skin and inner layers, pulp color and skin coloring, total titratable acidity (TTA), total soluble solids (TSS), visual index of dormancy breaking (VID), and fresh weight loss (FWL) were evaluated in this study. No significant difference (p < 0.05) were found for TTA, TSS, VID, FWL, and pulp color among treatments. It can be concluded that T3 promoted a faster curing (12 hours) of bulbs, which provided bulbs with drier skin and intense yellow color.