Waterborne hyperbranched alkyd-acrylic resin obtained by miniemulsion polymerization

Directory of Open Access Journals (Sweden)

Edwin Murillo

Full Text Available Abstract Four waterborne hyperbranched alkyd-acrylic resins (HBRAA were synthesized by miniemulsion polymerization from a hyperbranched alkyd resin (HBR, methyl methacrylate (MMA, butyl acrylate (BA and acrylic acid (AA, by using benzoyl peroxide (BPO and ammonium persulfate (AP as initiators. The reaction between HBR and acrylic monomers was evidenced by differential scanning calorimetric (DSC, nuclear magnetic resonance (NMR and gel permeation chromatography (GPC. The conversion percentage, glass transition temperature (Tg, content of acrylic polymer (determined by soxhlet extraction and molecular weight increased with the content of acrylic monomers used in the synthesis. The main structure formed during the synthesis was the HBRAA. The analysis by dynamic light scattering (DLS showed that the particle size distribution of HBRAA2, HBRAA3 and HBRAA4 resins were mainly monomodal. The film properties (gloss, flexibility, adhesion and drying time of the HBRAA were good.

[Preparation of clear thermosetting resin for veneered crown from several bisMEPP monomers (author's transl)].

Science.gov (United States)

Tanaka, T; Nakabayashi, N; Masuhara, E

1978-07-01

The whitish translucent shade of a thermosetting resin cured from a mixture of a 2,2-Bis (p-methacryloxy (ethoxy)1-2 phenyl)-propane monomer and PMMA pearls makes it difficult to reconstruct a shade of the natural tooth. The attempt to improve the transparency of the mixed polymer was made in this study. Varying the molecular weight of BisMEPP monomer, PMMA polymer and curing temperature, cured specimens were prepared and their transparency was measured with a spectrophotometer. The results obtained are as follows. 1) In any molecular weight of PMMA, BisMEPP with 2.3 to 3.3 average number of ethylene oxide linkage showed the highest transpalency on the specimen. 2) With increasing the curing temperature, transpalency of the specimens made from BisME4.0 PP increased. With another molecular of BisMEPP, transpalency of the cured specimens showed the highest transpalency at the curing temperature of 120 degrees C. 3) With increasing the molecular weight of PMMA, the transpalency increased.

Waterborne hyperbranched alkyd-acrylic resin obtained by mini emulsion polymerization

Energy Technology Data Exchange (ETDEWEB)

Murillo, Edwin, E-mail: edwinalbertomurillo@gmail.com [Grupo de Investigacion en Materiales Polimericos (GIMAPOL), Universidad Francisco de Paula Santander, San Jose de Cucuta (Colombia); Lopez, Betty [Grupo de Investigacion en Ciencia de los Materiales, Universidad de Antioquia, Calle, Medellin (Colombia)

2016-10-15

Four waterborne hyper branched alkyd-acrylic resins (HBRAA) were synthesized by mini emulsion polymerization from a hyper branched alkyd resin (HBR), methyl methacrylate (MMA), butyl acrylate (BA) and acrylic acid (AA), by using benzoyl peroxide (BPO) and ammonium persulfate (AP) as initiators. The reaction between HBR and acrylic monomers was evidenced by differential scanning calorimetric (DSC), nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The conversion percentage, glass transition temperature (T{sub g}), content of acrylic polymer (determined by soxhlet extraction) and molecular weight increased with the content of acrylic monomers used in the synthesis. The main structure formed during the synthesis was the HBRAA. The analysis by dynamic light scattering (DLS) showed that the particle size distribution of HBRAA2, HBRAA3 and HBRAA4 resins were mainly mono modal. The film properties (gloss, flexibility, adhesion and drying time) of the HBRAA were good. (author)

N-Acetyl Cysteine Depletes Reactive Oxygen Species and Prevents Dental Monomer-Induced Intrinsic Mitochondrial Apoptosis In Vitro in Human Dental Pulp Cells.

Directory of Open Access Journals (Sweden)

Yang Jiao

Full Text Available To investigate the involvement of intrinsic mitochondrial apoptosis in dental monomer-induced cytotoxicity and the influences of N-acetyl cysteine (NAC on this process.Human dental pulp cells (hDPCs were exposed to several dental monomers in the absence or presence of NAC, and cell viability, intracellular redox balance, morphology and function of mitochondria and key indicators of intrinsic mitochondrial apoptosis were evaluated using various commercial kits.Dental monomers exerted dose-dependent cytotoxic effects on hDPCs. Concomitant to the over-production of reactive oxygen species (ROS and depletion of glutathione (GSH, differential changes in activities of superoxide dismutase, glutathione peroxidase, and catalase were detected. Apoptosis, as indicated by positive Annexin V/propidium iodide (PI staining and activation of caspase-3, was observed after dental monomer treatment. Dental monomers impaired the morphology and function of mitochondria, and induced intrinsic mitochondrial apoptosis in hDPCs via up-regulation of p53, Bax and cleaved caspase-3, and down-regulation of Bcl-2. NAC restored cell viability, relieved oxidative stress and blocked the apoptotic effects of dental monomers.Dental monomers induced oxidative stress and mitochondrial intrinsic apoptosis in hDPCs. NAC could reduce the oxidative stress and thus protect hDPCs against dental monomer-induced apoptosis.

A comparative evaluation of effect of modern-curing lights and curing modes on conventional and novel-resin monomers

Science.gov (United States)

Roy, Konda Karthik; Kumar, Kanumuru Pavan; John, Gijo; Sooraparaju, Sujatha Gopal; Nujella, Surya Kumari; Sowmya, Kyatham

2018-01-01

Aim: The aim of this study is to compare and to evaluate effect of curing light and curing modes on the nanohybrid composite resins with conventional Bis-GMA and novel tricyclodecane (TCD) monomers. Methodology: Two nanohybrid composites, IPS empress direct and charisma diamond were used in this study. Light-emitting diode (LED)-curing unit and quartz-tungsten-halogen (QTH)-curing unit which were operated into two different modes: continuous and soft start. Based on the composite resin, curing lights, and mode of curing used, the samples were divided into 8 groups. After polymerization, the samples were stored for 48 h in complete darkness at 37°C and 100% humidity. The Vickers hardness (VK) of the surface was determined with Vickers indenter by the application of 200 g for 15 s. Three VK readings were recorded for each sample surface both on top and bottom surfaces. For all the specimens, the three hardness values for each surface were averaged and reported as a single value. The mean VK and hardness ratio were calculated. The depth of cure was assessed based on the hardness ratio. Results: Comparison of mean hardness values and hardness ratios was done using ANOVA with post hoc Tukey's test. Conclusion: Both QTH- and LED-curing units had shown the adequate depth of cure. Soft-start-curing mode in both QTH- and LED-curing lights had effectively increased microhardness than the continuous mode of curing. TCD monomer had shown higher hardness values compared with conventional Bis-GMA-containing resin. PMID:29628651

Monomers and Monomer Mixtures Used in Impregnation of Fibrous Materials

Energy Technology Data Exchange (ETDEWEB)

NONE

1968-10-15

Some important properties of monomers and polymers in relation to their use for reinforcement of fibrous materials are listed. Some monomers and their properties important in impregnation of fibrous materials are also listed. In general it is not advantageous to use a pure monomer for impregnation but rather a mixture of monomers or a mixture of a monomer and a low molecular weight polymer such as unsaturated polyester. Some of these mixtures which have been well studied in connection with WPC are listed together with some of their properties when used in WPC. Other monomer mixtures may well come in question and other monomers can probably be used. For instance, it is reported from Japan that the cheap monomer ethyleneoxide, which cannot be polymerized by gamma radiation as such, can be polymerized (in bulk) as a mixture with methylmethacrylate. Good results with WPC have generally been obtained without swelling agents but more is grafted if some swelling agent is used, and it is possible that a swelling agent might be useful in the case of fibre-boards. Solvents, plasticizers, crosslinkable natural resins, aromatic chlorinated hydrocarbons, and retardants can be added, and with their use the properties of WPC can be widely modified. For example, a chlorinated wax can act as retardant, can reduce the total dose of radiation and can increase the flame resistance simultaneously.

Thermal behavior of halogenated imidebismaleimide resins

International Nuclear Information System (INIS)

Mohammad, A.; Al-Halim, N.Z.

1995-01-01

Several new poly-halogenated malecimides, bismaleimides and therir copoly resins were synthessised thermally from their corresponding amic acids. The synthesis was accomplished by two way method (amic acid-polimide) instead of the well-known three way method (amic acid-imide-polyimide). Thermal characterization of monomers and their cured resins was achieved using differential thermal analysis (DTA), dynamic thermogravimetric analysis (TGA) and isothermal gravimetric analysis (IGA). The effect of halogen substituent, especially in the ortho postion, is clear in the imidization proces, while polymerization proceeds almost equally in all systems. Thermal properties of homo and copolymers were correlated with their chemical structures. (author). 15 refs., 4

The LOMOsup(R) process: a solution for residual monomers

International Nuclear Information System (INIS)

Derbyshire, R.L.

1979-01-01

Regulatory activity over the last several years has addressed the potential problems associated with the migration of residual monomers from a number of commodity food packages. Regardless of the outcome of current debates, it will always be desirable to reduce monomer levels to as low a level as economically practicable so that they do not become indirect additives. The LOMO process is a body of technology inclusive of an ionizing radiation treatment which can result in sharp reduction of residual monomer levels in commodity plastic resins. The process may be applicable to factory intermediates, raw resins, or finished articles. Depending upon the individual system and its monomers, LOMO treatment can result in reductions to levels which press today's analytical test capability. Industrial radiation processing is normally accomplished with electron beam accelerators. Electron beam processing continues to gain in understanding and acceptance as one of the very few basic methods by which energy can be imparted to an industrial process system. Typically, whole factories are constructed around one accelerator. (author)

Controlled catalytic and thermal sequential pyrolysis and hydrolysis of phenolic resin containing waste streams to sequentially recover monomers and chemicals

Science.gov (United States)

Chum, H.L.; Evans, R.J.

1992-08-04

A process is described for using fast pyrolysis in a carrier gas to convert a waste phenolic resin containing feedstreams in a manner such that pyrolysis of said resins and a given high value monomeric constituent occurs prior to pyrolyses of the resins in other monomeric components therein comprising: selecting a first temperature program range to cause pyrolysis of said resin and a given high value monomeric constituent prior to a temperature range that causes pyrolysis of other monomeric components; selecting, if desired, a catalyst and a support and treating said feedstreams with said catalyst to effect acid or basic catalyzed reaction pathways to maximize yield or enhance separation of said high value monomeric constituent in said first temperature program range to utilize reactive gases such as oxygen and steam in the pyrolysis process to drive the production of specific products; differentially heating said feedstreams at a heat rate within the first temperature program range to provide differential pyrolysis for selective recovery of optimum quantity of said high value monomeric constituent prior to pyrolysis of other monomeric components therein; separating said high value monomeric constituent; selecting a second higher temperature program range to cause pyrolysis of a different high value monomeric constituent of said phenolic resins waste and differentially heating said feedstreams at said higher temperature program range to cause pyrolysis of said different high value monomeric constituent; and separating said different high value monomeric constituent. 11 figs.

Determination of unreacted monomers in restorative dental resins based on dimethacrylate by NMR hydrogen; Determinacao do teor de monomero residual em resinas restauradoras a base de dimetacrilatos por RMN de hidrogenio

Energy Technology Data Exchange (ETDEWEB)

Correa, Ivo Carlos; Miranda Junior, Walter G. [Sao Paulo Univ., SP (Brazil). Faculdade de Odontologia. Dept. de Materiais Dentarios]. E-mail: ivo@fo.usp.br; Tavares, Maria Ines B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas]. E-mail: mibt@ima.ufrj.br

2001-07-01

The presence of unreacted monomers after photo-activation of dental composites causes mechanical and biological properties to decrease and could be detected by NMR analysis. The aim of this study was to evaluate the percentage of leachable monomers of light-cured composites under the effect of variations of exposure time of photo activation by nuclear magnetic resonance of hydrogen in solution (NMR{sup 1}H). The composite resins tested Z250 and Fill Magic obtained similar values of unreacted monomers (%) at photo curing time suggested by the manufacturer and values were also lower than Durafill and A110 concentrations. From the NMR results, one day extractable time was efficient to quantify the amount of residual monomers in the dental composites tested, unless for Durafill composite. (author)

Shelf Life of PMR Polyimide Monomer Solutions and Prepregs Extended

Science.gov (United States)

Alston, William B.; Scheiman, Daniel A.

2000-01-01

PMR (Polymerization of Monomeric Reactants) technology was developed in the mid-1970's at the NASA Glenn Research Center at Lewis Field for fabricating high-temperature stable polyimide composites. This technology allowed a solution of polyimide monomers or prepreg (a fiber, such as glass or graphite, impregnated with PMR polyimide monomers) to be thermally cured without the release of volatiles that cause the formation of voids unlike the non-PMR technology used for polyimide condensation type resins. The initial PMR resin introduced as PMR 15 is still commercially available and is used worldwide by aerospace industries as the state-of-the-art resin for high-temperature polyimide composite applications. PMR 15 offers easy composite processing, excellent composite mechanical property retention, a long lifetime at use temperatures of 500 to 550 F, and relatively low cost. Later, second-generation PMR resin versions, such as PMR II 50 and VCAP 75, offer improvements in the upper-use temperature (to 700 F) and in the useful life at temperature without major compromises in processing and property retention but with significant increases in resin cost. Newer versions of nontoxic (non-methylene dianiline) PMR resins, such as BAX PMR 15, offer similar advantages as originally found for PMR 15 but also with significant increases in resin cost. Thus, the current scope of the entire PMR technology available meets a wide range of aeronautical requirements for polymer composite applications.

Contact allergy to epoxy resin

DEFF Research Database (Denmark)

Bangsgaard, Nannie; Thyssen, Jacob Pontoppidan; Menné, Torkil

2012-01-01

Background. Epoxy resin monomers are strong skin sensitizers that are widely used in industrial sectors. In Denmark, the law stipulates that workers must undergo a course on safe handling of epoxy resins prior to occupational exposure, but the effectiveness of this initiative is largely unknown...... in an educational programme. Conclusion. The 1% prevalence of epoxy resin contact allergy is equivalent to reports from other countries. The high occurrence of epoxy resin exposure at work, and the limited use of protective measures, indicate that reinforcement of the law is required....

Differential scanning calorimetry of the effects of temperature and humidity on phenol-formaldehyde resin cure

Science.gov (United States)

X.-M. Wang; B. Riedl; A.W. Christiansen; R.L. Geimer

1994-01-01

Phenol-formaldehyde (PF) resin is a widely used adhesive in the manufacture of wood composites. However, curing behaviour of the resin under various environmental conditions is not well known. A differential scanning calorimeter was employed to characterize the degree of resin cure in this study. Resin-impregnated glass cloth samples with varied moisture contents (0,31...

Radiation Induced Crosslinking of Polyethylene in the Presence of Bifunctional Vinyl Monomers

DEFF Research Database (Denmark)

Joshi, M. S.; Singer, Klaus Albert Julius; Silverman, J.

1977-01-01

Several reports have been published showing that the radiation induced grafting of bifunctional vinyl monomers to low density polyethylene results in a product with an unusually high density of crosslinks. The same grafting reactions are shown to reduce the incipient gel dose by more than a factor...... of fifty. This paper is concerned with the apparent crosslinking produced by the radiation grafting of two monomers to polyethylene: acrylic acid and acrylonitrile....

Solventless LARC-160 Polyimide Matrix Resin. [applied for use in aerospace engineering

Science.gov (United States)

Stclair, T. L.; Jewell, R. A.

1978-01-01

The addition polyimide, LARC-160, which was originally synthesized from low cost liquid monomers as a laminating resin in ethanol, was prepared as a solventless, high viscosity, neat liquid resin. The resin was processed by hot-melt coating techniques into graphite prepreg with excellent tack and drape. Comparable data on graphite reinforced laminates made from solvent-coated and various hot-melt coated prepreg were generated. LARC-160, because of its liquid nature, can be easily autoclave processed to produce low void laminates. Liquid chromatographic fingerprints indicate good reaction control on resin scale ups. Minor changes in monomer ratios were also made to improve the thermal aging performance of graphite laminates.

Radiation-induced decomposition of anion exchange resins

International Nuclear Information System (INIS)

Baidak, Aliaksandr; LaVerne, Jay A.

2010-01-01

Radiation-induced degradation of the strongly basic anion exchange resin Amberlite TM IRA400 in NO 3 - , Cl - and OH - forms has been studied. The research focused on the formation of molecular hydrogen in the gamma-radiolysis of water slurries of these quaternary ammonium resins with varying water content. Extended studies with various electron scavengers (NO 3 - , N 2 O and O 2 ) prove an important role of e solv - in the formation of H 2 from these resins. An excess production of H 2 in these systems at about 85% water weight fraction was found to be due to trimethylamine, dimethylamine and other compounds that leach from the resin to the aqueous phase. Irradiations with 5 MeV 4 He ions were performed to simulate the effects of α-particles.

Formulation of eb-curable epoxy resin : some important parameters

International Nuclear Information System (INIS)

Dahlan bin Haji Mohd; Hosoi, Fumio; Sasaki, Takashi

1989-01-01

The works on the electron-beam curing of surface coatings using epoxy acrylic-based resins were discussed. The works covered among other things the effect of molecular weights of the resins on the physical properties of coatings and their physical and chemical characterizations. The emphasis was given to formulating the resins applicable to surface coatings. Curings were done on a low-energy electron beam accelerator operating at 250 kV. A number of parameters deemed important to formulations, such as the molecular weights of the oligomers and monomers, monomer ratios, and HEA additions were explored. It was found that one could modify the physical properties of the coatings by changing or adjusting those parameters. (author)

Development of radiation-curable resin based on natural rubber

Energy Technology Data Exchange (ETDEWEB)

Mohd, Dahlan; Harun, Abdul Ghani [Nuclear Energy Unit, Bangi, Selangor (Malaysia)

1994-12-31

A new radiation curable resin based on natural rubber has been developed. The resin was based on the reaction between low molecular weight epoxidised natural rubber and acrylic acid. When formulated with reactive monomers and photoinitiator, it solidified upon irradiation with UV light. The resin may find applications in coating for cellulosic-based substrates and pressure-sensitive adhesive.

Development of radiation-curable resin based on natural rubber

International Nuclear Information System (INIS)

Dahlan Mohd; Abdul Ghani Harun

1993-01-01

A new radiation curable resin based on natural rubber has been developed. The resin was based on the reaction between low molecular weight epoxidised natural rubber and acrylic acid. When formulated with reactive monomers and photoinitiator, it solidified upon irradiation with UV light. The resin may find applications in coating for cellulosic-based substrates and pressure-sensitive adhesive

Bisphenol A Release: Survey of the Composition of Dental Composite Resins.

Science.gov (United States)

Dursun, Elisabeth; Fron-Chabouis, Hélène; Attal, Jean-Pierre; Raskin, Anne

2016-01-01

Bisphenol A (BPA) is an endocrine disruptor with potential toxicity. Composite resins may not contain pure BPA, but its derivatives are widely used. Several studies found doses of BPA or its derivatives in saliva or urine of patients after composite resin placement. The aims of this study were to establish an exhaustive list of composite resins marketed in Europe and their composition, and to assess the extent of BPA derivatives used. A research on manufacturers' websites was performed to reference all composite resins marketed in Europe, then their composition was determined from both material safety data sheets and a standardized questionnaire sent to manufacturers. Manufacturers had to indicate whether their product contained the monomers listed, add other monomers if necessary, or indicate "not disclosed". 160 composite resins were identified from 31 manufacturers and 23 manufacturers (74.2%) responded to the survey. From the survey and websites, the composition of 130 composite resins (81.2%) was: 112 (86.2%) based on BPA derivatives, 97 (74.7%) on bis-GMA, 17 (13.1%) without monomer derived from BPA (UDMA, sometimes with TEGDMA) and 6 (4.6%) with UDMA (only); 1 (0.8%) did not contain a BPA derivative or UDMA or TEGDMA. Pure BPA was never reported. This work has established a list of 18 composite resins that contain no BPA derivative. Manufacturers should be required to report the exact composition of their products as it often remains unclear or incomplete.

Do CAD/CAM dentures really release less monomer than conventional dentures?

Science.gov (United States)

Steinmassl, Patricia-Anca; Wiedemair, Verena; Huck, Christian; Klaunzer, Florian; Steinmassl, Otto; Grunert, Ingrid; Dumfahrt, Herbert

2017-06-01

Computer-aided design (CAD)/computer-aided manufacturing (CAM) dentures are assumed to have more favourable material properties than conventionally fabricated dentures, among them a lower methacrylate monomer release. The aim of this study was to test this hypothesis. CAD/CAM dentures were generated from ten different master casts by using four different CAD/CAM systems. Conventional, heat-polymerised dentures served as control group. Denture weight and volume were measured; the density was calculated, and the denture surface area was assessed digitally. The monomer release after 7 days of water storage was measured by high-performance liquid chromatography. Whole You Nexteeth and Wieland Digital Dentures had significantly lower mean volume and weight than conventional dentures. Baltic Denture System and Whole You Nexteeth had a significantly increased density. Baltic Denture System had a significantly smaller surface area. None of the CAD/CAM dentures released significantly less monomer than the control group. All tested dentures released very low amounts of methacrylate monomer, but not significantly less than conventional dentures. A statistically significant difference might nevertheless exist in comparison to other, less recommendable denture base materials, such as the frequently used autopolymerising resins. CAD/CAM denture fabrication has numerous advantages. It enables the fabrication of dentures with lower resin volume and lower denture weight. Both could increase the patient comfort. Dentures with higher density might exhibit more favourable mechanical properties. The hypothesis that CAD/CAM dentures release less monomer than conventional dentures could, however, not be verified.

Method of modifying a vinyl chloride resin by utilizing radiation cross-linking polymerization

Energy Technology Data Exchange (ETDEWEB)

Kagiya, T; Fujimoto, T; Hosoi, F; Tsuneta, K; Atogawa, M

1970-08-26

The polyvinyl chloride is improved in its mechanical, thermal and chemical properties, with particular advantages gained in dimensional stability at temperatures higher than the plasticizing temperature. The process comprises irradiating a vinyl chloride resin with ionizing radiations in the presence of a vinyl acetate monomer. In this process, the irradiation of vinyl acetate effects cross-linking and the polymerization of the monomer simultaneously. The vinyl chloride resin may be a copolymer along with another monomer, a polyvinyl chloride derivative, a graft polymer of polyvinyl chloride, a mixture of vinyl chloride with another resin and a graft copolymer of vinyl chloride on another resin in any form. The addition of the vinyl acetate monomer to the vinyl chloride is not limited to any particular procedure. The vinyl acetate monomer may be added to the polyvinyl chloride in a quantity ranging from a trace to 200% by weight. The radiation dose may be 10/sup 2/ to 10/sup 9/, but preferably 10/sup 3/ roentgen. In one example, 36 parts by weight of market available vinyl acetate monomer immersed in 100 parts by weight of hard vinyl tube were placed in a stainless reacting vessel. After the replacement of inner air with nitrogen, the vessel was exposed to ..gamma.. beams of 4.8 x 10 roentgen from a Co-60 source. After dipping the exposed samples in boiled tetrahydrofuran for 48 hours, the insoluble substance in the samjle was 78.9% by weight. In addition, after heating at 180/sup 0/C for 30 minutes, the sample did not show any deformation.

Column chromatographic separation of Y3+ from Sr2+ by polymeric ionizable crown ether resins

International Nuclear Information System (INIS)

Wood, D.J.; Elshani, S.; Wai, C.M.; Bartsch, R.A.; Huntley, M.; Hartenstein, S.

1993-01-01

Condensation polymers containing subunits of crown ether carboxylic acid monomers are effective stationary phases for the chromatographic separation of Y 3+ and Sr 2+ . The pH range and metal loading capacities for the resins have been determined under equilibrium conditions. The resin can be regenerated for repeated use without losing its separation capability. Altering the molecular structure of the monomer (sym-dibenzo-16-crown-5-oxyacetic acid) by an alkyl substitution on the macrocyclic cavity decreases the loading capacity of the resin

Radiation induced ionic polymerisation and grafting of vinyl monomers

International Nuclear Information System (INIS)

Stannett, V.T.

1981-01-01

Some special aspects of the radiation induced ionic polymerisation and grafting of vinyl monomers will be described. In particular the effects of solvents on the cationic polymerisation of the vinyl ethers will be discussed in detail. The unequivocal free ion nature of the polymerisation makes such information of considerable general interest. Estimates of the propagation rate constants with free cation polymerisation in solvents of different dielectric constants and solvation powers will be presented. Finally, some observations on the radiation induced graft polymerisation of ethyl vinyl ether to poly(vinyl chloride) and to polypropylene will be presented. (author)

Development of a novel oxirane-acrylate composite restorative resin material

Science.gov (United States)

Sripathi Panditaradhyula, Anuhya

The need for resin with a long clinical life can be satiated through the novel formulation of varying concentrations of oxirane and acrylate monomers with an increase in filler loading in the sample, which will allow the creation of a resin that is less susceptible to chemical degradation along with improved mechanical properties. Various concentrations of oxirane and acrylate monomers with a three-component photoinitiation system, which is capable of both free radical (acrylate) and cationic (oxirane) initiation, are used. The resin composites were placed in the Speedmixer for 30 seconds and gravitation convection oven for one minute, repeated 5-7 times. The resin composites were used to create a 9.525 mm diameter * 1.5875 mm thick resin mold. The mold was then photocured for twenty seconds on both sides using VALO blue LED light. The Rockwell hardness and shore D durometer hardness served as relative measures of bonding between the monomers. The ideal formulation of oxirane and acrylate concentrations were used to perform the Instron 3 point bend test, as well as contact angle determination. The goal is to identify a resin with a clinical life twice that of the resins being used in practice. Potential findings include ideal oxirane and acrylate concentrations with the highest shore D durometer hardness, Rockwell hardness, contact angle values, and Instron 3 point bend test values. Ideal color, transparency and properties of the resin are taken into account. Optimization of oxirane and acrylate monomers, impact while using various filler components (salination, number of fillers), filler particle size variations and variations in using different filler concentrations are observed. Results of using micro and nano-sized monomers are also studied. Addition of fluorinated acrylate monomer to the micro and nano composite was the next goal. A comparison of all the above stated compositions to the control group 70/30 BisTEG was done. A study on the degradation behavior

Effect of food simulating liquids on release of monomers from two dental resin composites

Directory of Open Access Journals (Sweden)

Ghavam M

2010-06-01

Full Text Available "nBackground and Aims: The elution of residual monomers from cured dental composites to oral cavity has a harmful effect on human health and can affect their clinical durability. The purpose of this study was to evaluate the amount of eluted monomers (Bis-GMA, TEGDMA, UDMA from two types of composites (Gradia and P60 after exposure to food simulating liquids such as ethanol (25, 50, 75 % and heptane 50 % for 24 hours and 7 days. "nMaterials and Methods: Forty specimens of each composite were prepared. Equal numbers of each composite were immersed in tubes containing 2cc volumes of 25, 50, 75 % ethanole and 50 % heptane. The amount of eluted monomers in standard condition such as Bis-GMA, TEGDMA and UDMA was measured by GC/MS (Gas Chromatography/Mass Spectroscopy and results were statistically analysed by three way and one way ANOVA. P<0.05 was considered as the level of significancy. "nResults: The results showed that Gradia released more TEGDMA than P60. In assessing the effect of environment, the result showed that ethanol caused releasing monomers more than heptane and the concentration rate of 75 % ethanole resulted in most releasing of monomers. In assessing the effect of time, the observation showed that more monomers were released 7 days compared to 24 hours. Bis-GMA and UDMA were not detected in any solutions in these conditions. "nConclusion: Ethanole caused more release of monomers than heptane and 75 % ethanole released the most amount of monomers. Gradia released more amount of TEGDMA than P60.

21 CFR 177.1570 - Poly-1-butene resins and butene/ethylene copolymers.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Poly-1-butene resins and butene/ethylene copolymers... resins and butene/ethylene copolymers. The poly-1-butene resins and butene/ethylene copolymers identified... the catalytic polymerization of 1-butene liquid monomer. Butene/ethylene copolymers are produced by...

New monomers for high performance polymers

Science.gov (United States)

Gratz, Roy F.

1993-01-01

This laboratory has been concerned with the development of new polymeric materials with high thermo-oxidative stability for use in the aerospace and electronics industries. Currently, there is special emphasis on developing matrix resins and composites for the high speed civil transport (HSCT) program. This application requires polymers that have service lifetimes of 60,000 hr at 350 F (177 C) and that are readily processible into void-free composites, preferably by melt-flow or powder techniques that avoid the use of high boiling solvents. Recent work has focused on copolymers which have thermally stable imide groups separated by flexible arylene ether linkages, some with trifluoromethyl groups attached to the aromatic rings. The presence of trifluoromethyl groups in monomers and polymers often improves their solubility and processibility. The goal of this research was to synthesize several new monomers containing pendant trifluoromethyl groups and to incorporate these monomers into new imide/arylene ether copolymers. Initially, work was begun on the synthesis of three target compounds. The first two, 3,5-dihydroxybenzo trifluoride and 3-amino 5-hydroxybenzo trifluoride, are intermediates in the synthesis of more complex monomers. The third, 3,5-bis (3-amino-phenoxy) benzotrifluoride, is an interesting diamine that could be incorporated into a polyimide directly.

4-META opaque resin--a new resin strongly adhesive to nickel-chromium alloy.

Science.gov (United States)

Tanaka, T; Nagata, K; Takeyama, M; Atsuta, M; Nakabayashi, N; Masuhara, E

1981-09-01

1) A new adhesive opaque resin containing a reactive monomer, 4-methacryloxy-ethyl trimellitate anhydride (4-META), was prepared, and its application to thermosetting acrylic resin veneer crowns was studied. 2) The 4-META opaque resin was applied to a variety of nickel-chromium dental alloy specimens which had undergone different treatment, and endurance tests were conducted to evaluate the durability of adhesion. 3) Stable adhesion against water penetration was achieved with metal surfaces first etched with HCl and then oxidized with HNO3. A bond strength of 250 kg/cm2 was maintained even after immersion in water at 37 degrees C for 30 wk or at 80 degrees C for ten wk. Furthermore, this value did not decrease even after the specimens were subjected to 500 thermal cycles. 4) The 4-META opaque resin studied can eliminate the necessity for retention devices on metal castings. 5) The smooth 4-META opaque resin should have no adverse effects on gingivae.

Radiation-induced graft polymerization of amphiphilic monomers with different polymerization characteristics onto hydrophobic polysilane

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Hidenori; Iwasaki, Isao; Kunai, Yuichiro [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Sato, Nobuhiro, E-mail: sato-n@rri.kyoto-u.ac.j [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Matsuyama, Tomochika [Research Reactor Institute, Kyoto University, Asashironishi 2-1010, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

2011-08-15

The structures of poly(methyl-n-propylsilane) (PMPrS) amphiphilically modified through {gamma}-ray-induced graft polymerization were investigated with {sup 1}H NMR measurement. By the use of methyl methacrylate (MMA) or diethyl fumarate (DEF) as monomers for the graft polymerization, grafting yield rose with increasing total absorption dose and monomer concentrations, but decreased with increasing dose rate. This result means that grafting yield of modified PMPrS can be controlled by changing irradiation conditions. However, the number of PMMA or PDEF graft chains per PMPrS chain was estimated to be less than 1.0 by analysis of {sup 1}H NMR spectra, and this value was lower than that we had expected. To improve graft density, maleic anhydride (MAH), which is known as a non-homopolymerizable monomer in radical polymerization, was used as a monomer for grafting. As a result, high density grafting (one MAH unit for 4.2 silicon atoms) was attained. It demonstrates that the structure of {gamma}-ray-modified polysilane strongly depends on the polymerization characteristics of grafted monomers.

Reduced toxicity polyester resins and microvascular pre-preg tapes for advanced composites manufacturing

Science.gov (United States)

Poillucci, Richard

Advanced composites manufacturing broadly encapsulates topics ranging from matrix chemistries to automated machines that lay-up fiber-reinforced materials. Environmental regulations are stimulating research to reduce matrix resin formulation toxicity. At present, composites fabricated with polyester resins expose workers to the risk of contact with and inhalation of styrene monomer, which is a potential carcinogen, neurotoxin, and respiratory irritant. The first primary goal of this thesis is to reduce the toxicity associated with polyester resins by: (1) identification of potential monomers to replace styrene, (2) determination of monomer solubility within the polyester, and (3) investigation of approaches to rapidly screen a large resin composition parameter space. Monomers are identified based on their ability to react with polyester and their toxicity as determined by the Globally Harmonized System (GHS) and a green screen method. Solubilities were determined by the Hoftyzer -- Van Krevelen method, Hansen solubility parameter database, and experimental mixing of monomers. A combinatorial microfluidic mixing device is designed and tested to obtain distinct resin compositions from two input chemistries. The push for safer materials is complemented by a thrust for multifunctional composites. The second primary goal of this thesis is to design and implement the manufacture of sacrificial fiber materials suitable for use in automated fiber placement of microvascaular multifunctional composites. Two key advancements are required to achieve this goal: (1) development of a roll-to-roll method to place sacrificial fibers onto carbon fiber pre-preg tape; and (2) demonstration of feasible manufacture of microvascular carbon fiber plates with automated fiber placement. An automated method for placing sacrificial fibers onto carbon fiber tapes is designed and a prototype implemented. Carbon fiber tows with manual placement of sacrificial fibers is implemented within an

Method for curing alkyd resin compositions by applying ionizing radiation

International Nuclear Information System (INIS)

Watanabe, T.; Murata, K.; Maruyama, T.

1975-01-01

An alkyd resin composition is prepared by dissolving a polymerizable alkyd resin having from 10 to 50 percent of oil length into a vinyl monomer. The polymerizable alkyd resin is obtained by a half-esterification reaction of an acid anhydride having a polymerizable unsaturated group and an alkyd resin modified with conjugated unsaturated oil having at least one reactive hydroxyl group per one molecule. The alkyd resin composition thus obtained is coated on an article, and ionizing radiation is applied on the article to cure the coated film thereon. (U.S.)

Cure Kinetics of Benzoxazine/Cycloaliphatic Epoxy Resin by Differential Scanning Calorimetry

Science.gov (United States)

Gouni, Sreeja Reddy

Understanding the curing kinetics of a thermoset resin has a significant importance in developing and optimizing curing cycles in various industrial manufacturing processes. This can assist in improving the quality of final product and minimizing the manufacturing-associated costs. One approach towards developing such an understanding is to formulate kinetic models that can be used to optimize curing time and temperature to reach a full cure state or to determine time to apply pressure in an autoclave process. Various phenomenological reaction models have been used in the literature to successfully predict the kinetic behavior of a thermoset system. The current research work was designed to investigate the cure kinetics of Bisphenol-A based Benzoxazine (BZ-a) and Cycloaliphatic epoxy resin (CER) system under isothermal and nonisothermal conditions by Differential Scanning Calorimetry (DSC). The cure characteristics of BZ-a/CER copolymer systems with 75/25 wt% and 50/50 wt% have been studied and compared to that of pure benzoxazine under nonisothermal conditions. The DSC thermograms exhibited by these BZ-a/CER copolymer systems showed a single exothermic peak, indicating that the reactions between benzoxazine-benzoxazine monomers and benzoxazine-cycloaliphatic epoxy resin were interactive and occurred simultaneously. The Kissinger method and isoconversional methods including Ozawa-Flynn-Wall and Freidman were employed to obtain the activation energy values and determine the nature of the reaction. The cure behavior and the kinetic parameters were determined by adopting a single step autocatalytic model based on Kamal and Sourour phenomenological reaction model. The model was found to suitably describe the cure kinetics of copolymer system prior to the diffusion-control reaction. Analyzing and understanding the thermoset resin system under isothermal conditions is also important since it is the most common practice in the industry. The BZ-a/CER copolymer system with

Facile synthesis of allyl resinate monomer in an aqueous solution ...

Indian Academy of Sciences (India)

The synthesized monomer product appeared as a viscous liquid, with a viscosity of 460 mPa·s at 25◦C and a density of ... ated under high reaction temperature, which reduces the ... The use of DMF as an organic solvent also comes with.

Synthesis and characterisation of epoxy resins reinforced with carbon nanotubes and nanofibers.

Science.gov (United States)

Prolongo, S G; Gude, M R; Ureña, A

2009-10-01

Epoxy nanocomposites were fabricated using two kinds of nanofiller, amino-functionalized multi-walled carbon nanotubes (CNTs) and non-treated long carbon nanofibers (CNFs). The non-cured mixtures were analysed through viscosity measurements. The effect of the nanoreinforcement on the curing process was determined by differential scanning calorimetry. Finally, the characterisation of cured nanocomposites was carried out studying their thermo-mechanical and electrical behaviour. At room temperature, the addition of CNTs causes a viscosity increase of epoxy monomer much more marked than the introduction of CNFs due to their higher specific area. It was probed that in that case exists chemical reaction between amino-functionalized CNTs and the oxirane rings of epoxy monomer. The presence of nanoreinforcement induces a decrease of curing reaction rate and modifies the epoxy conversion reached. The glass transition temperature of the nanocomposites decreases with the contents of CNTs and CNFs added, which could be related to plasticization phenomena of the nanoreinforcements. The storage modulus of epoxy resin significantly increases with the addition of CNTs and CNFs. This augment is higher with amino-functionalized CNTs due, between other reasons, to the stronger interaction with the epoxy matrix. The electrical conductivity is greatly increased with the addition of CNTs and CNFs. In fact, the percolation threshold is lower than 0.25 wt% due to the high aspect ratio of the used nanoreinforcements.

A study on radiation-induced graft copolymerization of monomer onto natural silk fabric

International Nuclear Information System (INIS)

Xiang Zhengyu; Wan Dairong; He Qian

1995-02-01

In order to improve the properties of natural silk fabric, the mechanism and method of the radiation induced graft copolymerization of monomers onto natural silk fabric were studied. Three monomers, acrylamide, methylacrylamide and hydroxymethyl acrylamide, were selected for grafting test according to requirements of graft processing. The processing conditions of monomer infusion were studied. The properties of grafted samples were measured. The results are as follows: the rate of weight increasing is 10%∼29%; the rate of thickness increasing is 5%∼20%; the abrupt elasticity rose by 30%; the retarded elasticity rose by 12%; wet elasticity rose by 40%; and the brightness of colour and lustre were improved. It is concluded that while the radiation grafted silk kept its natural characteristics, other properties were improved. It became even chubby and thicker. (4 refs., 3 figs., 3 tabs.)

The influence of monomeric resin and filler characteristics on the performance of experimental resin-based composites (RBCs) derived from a commercial formulation.

LENUS (Irish Health Repository)

Hahnel, Sebastian

2012-04-01

To explore experimental RBCs derived from a successful commercially available RBC (Grandio) to investigate resin monomer blend and filler parameters (volume fraction, density and diameter) on RBC performance.

Correlations of norbornenyl crosslinked polyimide resin structures with resin thermo-oxidative stability, resin glass transition temperature and composite initial mechanical properties

Science.gov (United States)

Alston, William B.

1988-01-01

PMR (polymerization of monomeric reactants) methodology was used to prepare 70 different polyimide oligomeric resins and 30 different unidirectional graphite fiber/polyimide composites. Monomeric composition as well as chain length between sites of crosslinks were varied to examine their effects on resin thermo-oxidative stability and glass transition temperature (Tg) of the cured/postcured resins. A linear correlation of decreasing 316 C resin weight loss/surface area versus (1) decreasing aliphatic content, or (2) increasing benzylic/aliphatic content stoichiometry ratio over a wide range of resin compositions was observed. An almost linear correlation of Tg versus molecular distance between the crosslinks was also observed. An attempt was made to correlate Tg with initial composite mechanical properties (flexural strength and interlaminar shear strength). However, the scatter in mechanical strength data prevented obtaining a clear correlation. Instead, only a range of composite mechanical properties was obtained at 25, 288, and 316 C. Perhaps more importantly, what did become apparent during the correlation study was (1) the PMR methodology could be used to prepare composites from resins containing a wide variety of monomer modifications, (2) that these composites almost invariably provided satisfactory initial mechanical properties as long as the resins formulated exhibited satisfactory processing flow, and (3) that PMR resins exhibited predictable rates of 316 C weight loss/surface area based on their benzylic/aliphatic stoichiometery ratio.

Effect of solubility parameter of monomers on electron beam induced graft-polymerization onto polyethylene films

International Nuclear Information System (INIS)

Mori, Koji; Koshiishi, Kenji; Masuhara, Ken-ichi

1991-01-01

Electron beam induced graft-polymerization by the mutual irradiation technique of monomers with different solubility parameters δ onto low density polyethylene films (LDPE) and high density polyethylene films (HDPE) were investigated at high dose rates (25 Mrad per second). Graft-polymerization mechanisms were discussed on the basis of grafting rates, surface tensions, atomic ratios of surface by XPS, and SEM images of the grafted films. Grafting rates decreased with increasing δ of monomers, and grafting rates onto LDPE were larger than those onto HDPE. Graft chain contents on surface, which were evaluated in terms of surface tensions and atomic ratios of the surface, increased with increasing δ of monomers, and graft chain contents on surface of HDPE were higher than those of LDPE. It is assumed that mutual solubility of PE and monomers, i.e., infiltration of monomers into PE during graft-polymerization influence grafting rates and graft sites in films. In case of high mutual solubility, grafting rates were large and graft sites spread from the surface into bulk. On the other hand, in case of low mutual solubility, grafting rates were small and graft sites localized on the surface of films. (author)

Simultaneous determination of components released from dental composite resins in human saliva by liquid chromatography/multiple-stage ion trap mass spectrometry.

Science.gov (United States)

Hsu, Wei-Yi; Wang, Ven-Shing; Lai, Chien-Chen; Tsai, Fuu-Jen

2012-02-01

Dental composite resins are widely used for fixing teeth; however, the monomers used in dental composite resins have been found to be cytotoxic and genotoxic, namely triethylene glycol dimethacrylate (TEGDMA), urethane dimethacrylate (UDMA), and bisphenol A glycol dimethacrylate (Bis-GMA). In this study, we incubated dental composite resins with human saliva for demonstrating the released monomers and biodegradation products. A simple saliva sample dilution method without purification or derivatization was used for quantification. We found that liquid chromatography coupled with multiple-stage ion trap mass spectrometry (LC-MS(n) ) operated in selected reaction monitoring (SRM) mode was able to separate the three monomers within 10 min. The calibration curves were linear (R² >0.996) over a wide range for each monomer in saliva: TEGDMA, 5-500 ppb; UDMA, 5-100 ppb, and Bis-GMA, 5-700 ppb. Furthermore, several biodegradation products were discovered with data-dependent MS/MS scan techniques. Although TEGMA degradation products have previously been reported, we identified two previously unknown UDMA degradation products. The LC-MS/MS method developed in this study was able to successfully quantify monomers and their principal biodegradation products from dental composite resins in human saliva. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Immobilization of enzymes by radiation-induced polymerization of glass-forming monomers

International Nuclear Information System (INIS)

Yoshida, M.; Kumakura, M.; Kaetsu, I.

1979-01-01

The effect of cooling rate of a monomeric system on the porosity and activity of an immobilized enzyme prepared by radiation-induced polymerization of 2-hydroxyethyl methacrylate at low temperatures has been studied. Slow cooling gave the same effect on porosity of the polymer as decreasing the monomer concentration. A glass-forming solvent such as diethylene glycol was added to water to study the effect of the supercooling tendency of the solvent. Addition of diethylene glycol decreased porosity and also enzymic activity. Water was replaced by the miscible solvent p-dioxane and the immiscible solvent n-decane in order to clarify the effect of solvent. p-Dioxane had a similar effect to water on the relation between the monomer concentration, porosity and activity. On the other hand, polymer prepared from the system containing n-decane showed different immobilization properties owing to the presence of independent pores in the matrix. (author)

Photopolymerizable phosphate acrylates as comonomers in dental adhesives with or without triclosan monomer units

International Nuclear Information System (INIS)

Melinte, Violeta; Buruiana, Tinca; Aldea, Horia; Matiut, Simona; Silion, Mihaela; Buruiana, Emil C.

2014-01-01

Phosphate diacrylates (CO-DAP, TMP-DAP) based on castor oil or trimethylolpropane were synthesized and evaluated in dental adhesive formulations in comparison with 3-acryloyloxy-2-hydroxypropyl methacrylate phosphate (AMP-P). In an attempt to promote antibacterial activity, another photopolymerizable monomer (TCS-UMA) containing 5-chloro-2-(2,4-dichlorophenoxy)phenol moiety (triclosan) was prepared and incorporated in adhesive resins. Each of these monomers had a molecular structure confirmed by spectral methods. The photopolymerization rates for monomers (0.063–0.088 s −1 ) were lower than those determined in the monomer combinations (0.116–0.158 s −1 ) incorporating phosphate diacrylate (11 wt.%), BisGMA (33 wt.%), TEGDMA (10 wt.%), UDMA (10 wt.%) and HEMA (15 wt.%), the degree of conversion varying between 63.4 and 74.5%. The formed copolymers showed high values for water sorption (18.65–57.02 μg/mm 3 ) and water solubility (3.51–13.38 μg/mm 3 ), and the contact angle was dependent on the presence of CO-DAP (θ F1 : 66.67°), TMP-DAP (θ F2 : 55.05°) or AMP-P (θ F3 : 52.90°) in the photocrosslinked specimens compared to the sample without phosphate monomer (θ F4 : 82.14°). The scanning electron microscopy image of the dentin–resin composite interface after applying our F1 formulation (pH: 4.1) and its light-curing for 20 s supports the evidence of the formation of the hybrid layer with the tooth structure created by self-etching approach, with no gaps or cracks in the adhesive. A comparative analysis of the adhesion achieved with commercial adhesive systems (Single Bond Universal, C-Bond) rather indicates similarities than differences between them. The addition of triclosan methacrylate (1 wt.%) into the formulation inhibited the bacterial growth of the Streptococcus mutans and Escherichia coli in the direct contact area due to the covalently linked antibacterial monomer. - Highlights: • Synthesis of photopolymerizable phosphate acrylate

Electroactive polymer gels based on epoxy resin

Science.gov (United States)

Samui, A. B.; Jayakumar, S.; Jayalakshmi, C. G.; Pandey, K.; Sivaraman, P.

2007-04-01

Five types of epoxy gels have been synthesized from common epoxy resins and hardeners. Fumed silica and nanoclay, respectively, were used as fillers and butyl methacrylate/acrylamide were used as monomer(s) for making interpenetrating polymer networks (IPNs) in three compositions. Swelling study, tensile property evaluation, dynamic mechanical thermal analysis, thermo-gravimetric analysis, scanning electron microscopy and electroactive property evaluation were done. The gels have sufficient mechanical strength and the time taken for bending to 20° was found to be 22 min for forward bias whereas it was just 12 min for reverse bias.

Simple introduction of sulfonic acid group onto polyethylene by radiation-induced cografting of sodium styrenesulfonate with hydrophilic monomers

International Nuclear Information System (INIS)

Tsuneda, Satoshi; Saito, Kyoichi; Furusaki, Shintaro; Sugo, Takanobu; Makuuchi, Keizo

1993-01-01

The sulfonic acid (SO 3 H) group was readily introduced into a polyethylene (PE) membrane by radiation-induced cografting of sodium styrenesulfonate (SSS) with hydrophilic monomers such as acrylic acid (AAc) and hydroxyethyl methacrylate (HEMA). The density of SSS grafted onto the PE membrane was determined as a function of molar ratio of hydrophilic monomer to SSS in the monomer mixture. Immersion of the electron-beam-irradiated PE membrane into the mixture of SSS and HEMA for 5 h at 323 K provided to the SO 3 H density of 2.5 mol/kg of the H-type product

Bonding auto-polymerising acrylic resin to acrylic denture teeth.

LENUS (Irish Health Repository)

Nagle, Susan

2009-09-01

This study investigated the effect of surface treatments on the shear bond strength of an auto-polymerising acrylic resin cured to acrylic denture teeth. The surface treatments included a combination of grit-blasting and\\/or wetting the surface with monomer. Samples were prepared and then stored in water prior to shear testing. The results indicated that the application of monomer to the surface prior to bonding did not influence the bond strength. Grit blasting was found to significantly increase the bond strength.

Going greener: Synthesis of fully biobased unsaturated polyesters for styrene crosslinked resins with enhanced thermomechanical properties

Directory of Open Access Journals (Sweden)

C. S. M. F. Costa

2017-11-01

Full Text Available The main goal of this work was the development of fully biobased unsaturated polyesters (UPs that upon crosslinking with unsaturated monomers (UM could lead to greener unsaturated polyester resins (UPRs with similar thermomechanical properties to commercial fossil based UPR. After the successful synthesis of the biobased UPs, those were crosslinked with styrene (Sty, the most commonly used monomer, and the influence of the chemical structure of the UPs on the thermomechanical characteristics of UPRs were evaluated. The properties were compared with those of a commercial resin (Resipur 9837©. The BioUPRs presented high gel contents and contact angles that are similar to the commercial resin. The thermomechanical properties were evaluated by dynamic mechanical thermal analysis (DMTA and it was found that the UPR synthesized using propylene glycol (PG, succinic acid (SuAc and itaconic acid (ItAc presented very close thermomechanical properties compared to the commercial resin.

Photopolymerizable phosphate acrylates as comonomers in dental adhesives with or without triclosan monomer units

Energy Technology Data Exchange (ETDEWEB)

Melinte, Violeta [Petru Poni Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, 700487 Iasi (Romania); Buruiana, Tinca, E-mail: tbur@icmpp.ro [Petru Poni Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, 700487 Iasi (Romania); Aldea, Horia [Gr. T. Popa University of Medicine and Pharmacy, Faculty of Dentistry, Iasi (Romania); Matiut, Simona [Praxis Medical Investigations, 33 Independence, 700102 Iasi (Romania); Silion, Mihaela; Buruiana, Emil C. [Petru Poni Institute of Macromolecular Chemistry, 41 A Gr. Ghica Voda Alley, 700487 Iasi (Romania)

2014-01-01

Phosphate diacrylates (CO-DAP, TMP-DAP) based on castor oil or trimethylolpropane were synthesized and evaluated in dental adhesive formulations in comparison with 3-acryloyloxy-2-hydroxypropyl methacrylate phosphate (AMP-P). In an attempt to promote antibacterial activity, another photopolymerizable monomer (TCS-UMA) containing 5-chloro-2-(2,4-dichlorophenoxy)phenol moiety (triclosan) was prepared and incorporated in adhesive resins. Each of these monomers had a molecular structure confirmed by spectral methods. The photopolymerization rates for monomers (0.063–0.088 s{sup −1}) were lower than those determined in the monomer combinations (0.116–0.158 s{sup −1}) incorporating phosphate diacrylate (11 wt.%), BisGMA (33 wt.%), TEGDMA (10 wt.%), UDMA (10 wt.%) and HEMA (15 wt.%), the degree of conversion varying between 63.4 and 74.5%. The formed copolymers showed high values for water sorption (18.65–57.02 μg/mm{sup 3}) and water solubility (3.51–13.38 μg/mm{sup 3}), and the contact angle was dependent on the presence of CO-DAP (θ{sub F1}: 66.67°), TMP-DAP (θ{sub F2}: 55.05°) or AMP-P (θ{sub F3}: 52.90°) in the photocrosslinked specimens compared to the sample without phosphate monomer (θ{sub F4}: 82.14°). The scanning electron microscopy image of the dentin–resin composite interface after applying our F1 formulation (pH: 4.1) and its light-curing for 20 s supports the evidence of the formation of the hybrid layer with the tooth structure created by self-etching approach, with no gaps or cracks in the adhesive. A comparative analysis of the adhesion achieved with commercial adhesive systems (Single Bond Universal, C-Bond) rather indicates similarities than differences between them. The addition of triclosan methacrylate (1 wt.%) into the formulation inhibited the bacterial growth of the Streptococcus mutans and Escherichia coli in the direct contact area due to the covalently linked antibacterial monomer. - Highlights: • Synthesis of

Radiation induced grafting of monomers onto natural rubber : processes and applications

International Nuclear Information System (INIS)

Sunny Sebastian, M.

2001-01-01

Full text: Certain inherent mechanical properties of natural rubber (NR) can be modified by grafting vinyl monomers onto the polymer backbone. This paper described the gamma radiation induced graft copolymerization of methyl methacrylate (MMA), styrene and acrylonitrile (AN) onto NR. The graft copolymers can be crosslinked by sulphur and organic accelerators. The crosslinked graft copolymers show improved modulus and hardness in their films compared to NR. However the tensile strength of the films is reduced by grafting. The methods for preparing the graft copolymers, their properties and applications are briefly described

Elution of Monomers from Provisional Composite Materials

Directory of Open Access Journals (Sweden)

Simon Daniel Schulz

2015-01-01

Full Text Available The aim of this study was to evaluate the elution of substances from different materials used for the manufacturing of temporary indirect restorations, after storage in saliva and ethanol 75%. 10 samples of three chemically cured materials (Protemp 3 Garant, Systemp.c&b, and Trim and one light-cured material (Clip F were stored in saliva and ethanol 75% for 24 h, 7, and days 28 days. From the storage media at each time period, samples were prepared and analysed by LC-MS/MS, in order to access the elution of monomers. The results differed among the materials (P ≤ 0.05. No monomers were detected in the samples of Protemp 3 Garant and Clip F. Substances were detected only in ethanol samples of Systemp.c&b and Trim. The amount of BisGMA, TEGDMA, and UDMA 2 released from Systemp.c&b was higher compared to Trim. Storage time affected the release of substances (P ≤ 0.05. The highest release was observed within the first 24 h. It can be concluded that provisional resin composite materials do not show high release of monomers and this release is material dependent. However, the detection of additional peaks during the analysis, suggesting the formation of by-products of the eluted substances, may not be in favour of these materials with respect to their toxicity.

Cell death effects of resin-based dental material compounds and mercurials in human gingival fibroblasts

Energy Technology Data Exchange (ETDEWEB)

Reichl, Franz-Xaver [Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany); Esters, Magali; Simon, Sabine; Seiss, Mario [Walther-Straub-Institute of Pharmacology and Toxicology, Munich (Germany); Kehe, Kai [Bundeswehr Institute of Pharmacology and Toxicology, Munich (Germany); Kleinsasser, Norbert [University of Regensburg, Head and Neck Surgery, Department of Otolaryngology, Regensburg (Germany); Folwaczny, Matthias; Glas, Juergen; Hickel, Reinhard [Ludwig-Maximilians-University, Department of Operative Dentistry and Periodontology, Munich (Germany)

2006-06-15

In order to test the hypothesis that released dental restorative materials can reach toxic levels in human oral tissues, the cytotoxicities of the resin-based dental (co)monomers hydroxyethylmethacrylate (HEMA), triethyleneglycoldimethacrylate (TEGDMA), urethanedimethacrylate (UDMA), and bisglycidylmethacrylate (BisGMA) compared with methyl mercury chloride (MeHgCl) and the amalgam component mercuric chloride (HgCl{sub 2}) were investigated on human gingival fibroblasts (HGF) using two different test systems: (1) the modified XTT-test and (2) the modified H 33342 staining assay. The HGF were exposed to various concentrations of the test-substances in all test systems for 24 h. All tested (co)monomers and mercury compounds significantly (P<0.05) decreased the formazan formation in the XTT-test. EC{sub 50} values in the XTT assay were obtained as half-maximum-effect concentrations from fitted curves. Following EC{sub 50} values were found (mean [mmol/l]; s.e.m. in parentheses; n=12; * significantly different to HEMA): HEMA 11.530 (0.600); TEGDMA* 3.460 (0.200); UDMA* 0.106 (0.005); BisGMA* 0.087 (0.001); HgCl{sub 2}* 0.013 (0.001); MeHgCl* 0.005 (0.001). Following relative toxicities were found: HEMA 1; TEGDMA 3; UDMA 109; BisGMA 133; HgCl{sub 2} 887; MeHgCl 2306. A significant (P<0.05) increase of the toxicity of (co)monomers and mercurials was found in the XTT-test in the following order: HEMA < TEGDMA < UDMA < BisGMA < HgCl{sub 2} < MeHgCl. TEGDMA and MeHgCl induced mainly apoptotic cell death. HEMA, UDMA, BisGMA, and HgCl{sub 2} induced mainly necrotic cell death. The results of this study indicate that resin composite components have a lower toxicity than mercury from amalgam in HGF. HEMA, BisGMA, UDMA, and HgCl{sub 2} induced mainly necrosis, but it is rather unlikely that eluted substances (solely) can reach concentrations, which might induce necrotic cell death in the human physiological situation, indicating that other (additional) factors may be involved in

Residual monomer content determination in some acrylic denture base materials and possibilities of its reduction

Directory of Open Access Journals (Sweden)

Kostić Milena

2009-01-01

Full Text Available Background/Aim. Polymethyl methacrylate is used for producing a denture basis. It is a material made by the polymerization process of methyl methacrylate. Despite of the polymerization type, there is a certain amount of free methyl methacrylate (residual monomer incorporated in the denture, which can cause irritation of the oral mucosa. The aim of this study was to determine the amount of residual monomer in four different denture base acrylic resins by liquid chromatography and the possibility of its reduction. Methods. After the polymerization, a postpolymerization treatment was performed in three different ways: in boiling water for thirty minutes, with 500 W microwaves for three minutes and in steam bath at 22º C for one to thirty days. Results. The obtained results showed that the amount of residual monomer is significantly higher in cold polymerizing acrylates (9.1-11%. The amount of residual monomer after hot polymerization was in the tolerance range (0.59- 0.86%. Conclusion. The obtained results denote a low content of residual monomer in the samples which have undergone postpolymerization treatment. A lower percent of residual monomer is established in samples undergone a hot polymerization.

A conditioning process for ion exchanger resins contaminated with radioactive elements

International Nuclear Information System (INIS)

Legros, R.; Wiegert, B.; Zeh, J.L.

1993-01-01

Ion exchanger resins are embedded in a pre-polymer syrup prepared from acrylic monomers having high boiling point. A curing catalyst (a peroxide) and an activation agent (a tertiary amine) are added. 12 examples are given. 9 p

Fully-differential spectrophotometry determination of trace thorium in uranium-containing waste water separated by CL-TBP levextrel resin

International Nuclear Information System (INIS)

You Jiannan

2000-01-01

A method for separation by CL-TBP levextrel resin and determination of trace thorium in uranium-containing waste water by fully-differential spectrophotometry is developed. In 4 mol/L HNO 3 medium, in presence of tartaric acid, CL-TBP levextrel resin is used for adsorption of thorium and separating from other elements. The thorium on the resin is stripped by 4 mol/L HCl, with oxalic acid and urea as screening agent, thorium forms red complex with arsenazo III. The maximum absorption of the complex is at 668 nm, and the molar absorptivity is 1.27 x 10 5 L/(mol·cm) . The complex can be steady for 2.5 h. By regulating micro-current of differential spectrophotometry, the method can realize determination with high precision. Sensitivity of this method increase 10 times than usual spectrophotometry. The relative standard deviation is better than +- 5% and recovery of thorium is 99%-107%

Synthesis and evaluation of novel siloxane-methacrylate monomers used as dentin adhesives.

Science.gov (United States)

Ge, Xueping; Ye, Qiang; Song, Linyong; Misra, Anil; Spencer, Paulette

2014-09-01

The objectives of this study were to synthesize two new siloxane-methacrylate (SM) monomers for application in dentin adhesives and to investigate the influence of different functionality of the siloxane-containing monomers on the adhesive photopolymerization, water sorption, and mechanical properties. Two siloxane-methacrylate monomers (SM1 and SM2) with four and eight methacrylate groups were synthesized. Dentin adhesives containing BisGMA, HEMA and the siloxane-methacrylate monomers were photo-polymerized. The experimental adhesives were compared with the control adhesive (HEMA/BisGMA, 45/55, w/w) and characterized with regard to degree of conversion (DC), water miscibility of the liquid resin, water sorption and dynamic mechanical analysis (DMA). The experimental adhesives exhibited improved water miscibility as compared to the control. When cured in the presence of 12 wt% water to simulate the wet environment of the mouth, the SM-containing adhesives showed DC comparable to the control. The experimental adhesives showed higher rubbery modulus than the control under dry conditions. Under wet conditions, the mechanical properties of the formulations containing SM monomer with increased functionality were comparable with the control, even with more water sorption. The concentration and functionality of the newly synthesized siloxane-methacrylate monomers affected the water miscibility, water sorption and mechanical properties of the adhesives. The experimental adhesives show improved water compatibility compared with the control. The mechanical properties were enhanced with an increase of the functionality of the siloxane-containing monomers. The results provide critical structure/property relationships and important information for future development of durable, versatile siloxane-containing dentin adhesives. Published by Elsevier Ltd.

Process for hardening synthetic resins by ionizing radiation

International Nuclear Information System (INIS)

Hesse, W.; Ritz, J.

1975-01-01

Synthetic resins containing hydroxy groups and polymerizable carbon-carbon bonds are reacted with diketenes to yield aceto ester derivatives, which when reacted with metal compounds to form chelates, and mixed with copolymerizable monomers, are capable of being hardened by unusually low radiation doses to form coatings and articles with superior properties. (E.C.B.)

Influence of the molecular structure on hydrolyzability of epoxy resins

International Nuclear Information System (INIS)

Pays, M.F.

1996-01-01

EDF has decided to use glass reinforced composites for certain pipework in Pressurized Water Reactors (service water, emergency-supplied service water, fine pipe works, etc...) as a replacement for traditional materials. In practice, steel is prone to rapid corrosion in these circuits; introducing composites could prove economically viable if their long term behaviour can be demonstrated. However, composite materials can undergo deterioration in service through hydrolysis of the resin or the fibre-matrix interface. Different resins can be chosen depending on the programmed use. A first study has covered the hydrolyzability of polyester and vinyl ester resins. The present document undertakes the resistance to hydrolysis of epoxy resins, concentrating on those reputed to withstand high temperatures. This research uses model monomer, linking the molecular structure of the materials to their resistance to hydrolysis. (author)

Radiation processed composite materials of wood and elastic polyester resins

International Nuclear Information System (INIS)

Tapolcai, I.; Czvikovszky, T.

1983-01-01

The radiation polymerization of multifunctional unsaturated polyester-monomer mixtures in wood forms interpenetrating network system. The mechanical resistance (compression, abrasion, hardness, etc.) of these composite materials are generally well over the original wood, however the impact strength is almost the same or even reduced, in comparison to the wood itself. An attempt is made using elastic polyester resins to produced wood-polyester composite materials with improved modulus of elasticity and impact properties. For the impregnation of European beech wood two types of elastic unsaturated polyester resins were used. The exothermic effect of radiation copolymerization of these resins in wood has been measured and the dose rate effects as well as hardening dose was determined. Felxural strength and impact properties were examined. Elastic unsaturated polyester resins improved the impact strength of wood composite materials. (author)

Structure-to-property relationships in addition cured polymers. II - Resin Tg and composite initial mechanical properties of norbornenyl cured polyimide resins

Science.gov (United States)

Alston, William B.

1986-01-01

PRM (polymerization of monomeric reactants) methodology was used to prepare thirty different polyimide oligomeric resins. Monomeric composition as well as chain length between sites of crosslinks were varied to examine their effects on glass transition temperature (Tg) of the cured/postcured resins. An almost linear correlation of Tg versus molecular distance between the crosslinks was observed. An attempt was made to correlate Tg with initial mechanical properties (flexural strength and interlaminar shear strength) of unidirectional graphite fiber composites prepared with these resins. However, the scatter in mechanical strength data prevented obtaining as clear a correlation as was observed for the structural modification/crosslink distance versus Tg. Instead, only a range of composite mechanical properties was obtained at the test temperatures studied (room temperature, 288 and 316 C). Perhaps more importantly, what did become apparent during the attempted correlation study was: (1) that PMR methodology could be used to prepare composites from resins that contain a wide variety of monomer modifications, and (2) that these composites almost invariably provided satisfactory initial mechanical properties as long as the resins selected were melt processable.

The effect of the polymerization initiator and light source on the elution of residual Bis-GMA and TEGDMA monomers: A study using liquid chromatography with UV detection.

Science.gov (United States)

Denis, Aline B; Diagone, Cristina A; Plepis, Ana M G; Viana, Rommel B

2015-12-05

A method for the extraction and quantification of two residual monomers, bisphenol glycidyl dimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA), that were evaluated using high efficiency liquid chromatography with UV detection was developed and validated in this study. Three types of solvents were applied in the extraction of the monomers (methanol, ethanol and acetonitrile), where the highest extraction efficiency was obtained using acetonitrile. The different resins were prepared by photoactivation of Bis-GMA and TEGDMA monomers. Additionally, the effects of the addition of two photoinitiators (camphorquinone (CQ) and phenyl propanodione (PPD) and that of a co-initiator (N,N-dimethyl-p-toluidine) were also analyzed. When only the CQ photoinitiator was used, a smaller amount of residual monomers was obtained, whereas a larger amount was obtained with PPD. When the two photoinitiators were used in the same matrix, however, no significant changes were observed in relation to the amount of residual TEGDMA monomers. For the addition of the co-initiator, there were no large changes in the extraction of residual monomers. The effect of the two photoactivation sources (halogen lamp and LED) led to small differences in the elution of the two monomers, although all of the resins differed significantly when photoactivated with a LED. Quantum chemical calculations using Density Functional Theory were carried out to characterize several molecular properties of each monomer. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthesis and properties of hydroxy acrylic resin with high solid content

Science.gov (United States)

Yu, Zhen; Hu, Mingguang; Cui, Han; Xiao, Jijun

2017-10-01

Manufacturers of automotive repair finishes are tending to reduce more and more the level of volatile organic compounds in their paints in order to comply with increasingly strict environmental legislation. A high solid hydroxy acrylic resin was synthesised using CARDURA E10 and a type of hydroxyacrylic acid resin, its' acid value, hydroxylvalue, viscosity, structure, morphology was measured and film-forming properties after curing were characterised. The results show that the addition of CARDURA E10 in the copolymer composition significantly reduced the viscosity of the polymer system, improved the solid content of the resin and the physical properties of the coating. The hydroxyl acrylate resin with solid content of 90% and excellent comprehensive performance were successfully prepared by controlling the initiator dosage, polymerization temperature and monomer ratio.

Dental Cements for Luting and Bonding Restorations: Self-Adhesive Resin Cements.

Science.gov (United States)

Manso, Adriana P; Carvalho, Ricardo M

2017-10-01

Self-adhesive resin cements combine easy application of conventional luting materials with improved mechanical properties and bonding capability of resin cements. The presence of functional acidic monomers, dual cure setting mechanism, and fillers capable of neutralizing the initial low pH of the cement are essential elements of the material and should be understood when selecting the ideal luting material for each clinical situation. This article addresses the most relevant aspects of self-adhesive resin cements and their potential impact on clinical performance. Although few clinical studies are available to establish solid clinical evidence, the information presented provides clinical guidance in the dynamic environment of material development. Copyright © 2017 Elsevier Inc. All rights reserved.

Composite plastic coatings and face rolled materials technology, energy- and environment-saving, based on irradiation of liquid monomers by broad and high-current electron beams in vacuum

Science.gov (United States)

Vaisburd, David

1994-05-01

The technology is based on the well-known process of hardening some organic liquid monomers and oligomers (resins and lacquers) under the action of ionizing radiation, i.e. electron, ion, ultra-violet, laser, and X-ray beams. The main mechanism of hardening is 3D polymerization of initial monomers induced by irradiation. First of all 1D polymer chains are created. And the next stage is cross-linking of them. Numerical attempts to apply such a process for plastic materials production met some earnest difficulties. Our decision to perform the whole processing in vacuum changed radically the main properties of radiation induced hardening technology. The inhibition of polymerization by reactive oxygen became unessential. The output window foil of accelerator became unnecessary. Application of super broad beams such as 1 sq.m became possible. The entire efficiency of grid electricity was increased to 60% and it was not the limit. One of the main advantages is that the processing carried out in vacuum may satisfy the highest ecological standards. The technology developed is contamination free and environment-saving.

Kinetic Parameters during Bis-GMA and TEGDMA Monomer Polymerization by ATR-FTIR: The Influence of Photoinitiator and Light Curing Source

Directory of Open Access Journals (Sweden)

Aline B. Denis

2016-01-01

Full Text Available This study aimed to analyze the kinetic parameters of two monomers using attenuated total reflectance Fourier transform infrared (ATR-FTIR: 2,2-bis-[4-(2-hydroxy-3-methacryloxypropyl-1-oxy-phenyl] propane (Bis-GMA and triethylene glycol dimethacrylate (TEGDMA. The following were calculated to evaluate the kinetic parameters: maximum conversion rate (Rpmax, time at the maximum polymerization rate (tmax, conversion at Rpmax, and total conversion recorded at the maximum conversion point after 300 s. Camphorquinone (CQ and phenyl propanedione (PPD were used in this study as photoinitiators, whereas N,N-dimethyl-p-toluidine (DMPT amine was used as a coinitiator. LED apparatus and halogen lamp were used in turn to evaluate the effect that light source had on the monomer kinetics. The mass concentration ratio for the three resin preparations was 0.7 : 0.3 for Bis-GMA and TEGDMA: R1 (CQ + DMPT, R2 (PPD + DMPT, and R3 (PPD + CQ + DMPT. The PPD association with the CQ photoinitiator altered the polymerization kinetics compared to a resin containing only the CQ photoinitiator. The light sources exhibited no significant differences for tmax of R1 and R3. Resins containing only the PPD initiator exhibited a higher tmax than those containing only CQ. However, the Rpmax decreased for resins containing the PPD photoinitiator.

Fabrication and Evaluation of Graphite Fiber-Reinforced Polyimide Composite Tube Forms Using Modified Resin Transfer Molding

Science.gov (United States)

Exum, Daniel B.; Ilias, S.; Avva, V. S.; Sadler, Bob

1997-01-01

The techniques necessary for the fabrication of a complex three-dimensional tubular form using a PMR-type resin have been developed to allow for the construction of several tubes with good physical and mechanical properties. Employing established resin transfer molding practices, the relatively non-hazardous AMB-21 in acetone formulation was used to successfully impregnate four layers of AS4 braided graphite fiber preform previously loaded around an aluminum cylindrical core in an enclosed mold cavity. Using heat and vacuum, the solvent was evaporated to form a prepreg followed by a partial imidization and removal of condensation products. The aluminum core was replaced by a silicone rubber bladder and the cure cycle continued to the final stage of 550 F with a bladder internal pressure of 200 lbs/sq in while simultaneously applying a strong vacuum to the prepreg for removal of any additional imidization products. A combination of several modifications to the standard resin transfer molding methodology enabled the mold to 'breathe', allowing the imidization products a pathway for escape. AMB-21 resin was chosen because of the carcinogenic nature of the primary commercial polyimide PMR-15. The AMB-21 resin was formulated using commercially available monomers or monomer precursors and dissolved in a mixture of methyl alcohol and acetone. The viscosity of the resulting monomer solution was checked by use of a Brookfield rheometer and adjusted by adding acetone to an easily pumpable viscosity of about 600 cP. In addition, several types of chromatographic and thermal analyses were of the braids, and excess handling of the preforms broke some of the microscopic fibers, needlessly decreasing the strength of the finished part. In addition, three dimensional braided preforms with fibers along the length of the tube will be significantly stronger in tension than the braided preforms used in this study.

[Analysis of anatomical pieces preservation with polyester resin for human anatomy study].

Science.gov (United States)

de Oliveira, Ítalo Martins; Mindêllo, Marcela Maria Aguiar; Martins, Yasmin de Oliveira; da Silva Filho, Antônio Ribeiro

2013-01-01

To evaluate the use of polyester resin in preserving anatomical specimens for the study of human anatomy. We used 150 anatomical specimens, comprised of unfixed (fresh), fixed in 10% formalin and vascular casts of organs injected with vinyl acetate and polyester resin. The solution used consisted of polyester resin with the diluent styrene monomer and catalyst (peroxol). After embedding in this solution, models in transparent resin were obtained, allowing full observation of structures and conservation of the specimens used. upon evaluation of the specimens, we observed a high degree of transparency, which promoted a complete visualization of structures with perfect preservation of the anatomy. The average time for the completion of the embedding was 48 hours. Only 14 specimens (9.3%) were lost during the preparation. Polyester resin can be used for preserving anatomical specimens for teaching human anatomy in a practical, aesthetic and durable way.

Radio-iodide uptake by modified poly (glycidyl methacrylate) as anion exchange resin

Energy Technology Data Exchange (ETDEWEB)

Othman, Sameh H. [Atomic Energy Authority, Cairo (Egypt). Nuclear Research Center; Atomic Energy Authority, Cairo (Egypt). Second Research Reactor; Elbarbary, Ahmed M. [Atomic Energy Authority, Cairo (Egypt). Radiation Research of Polymer Chemistry Dept.; Rashad, Ghada; Fasih, T.W. [Atomic Energy Authority, Cairo (Egypt). Hot Laboratories Center

2017-03-01

Poly(glycidyl methacrylate) (PGMA) microspheres were prepared by radiation induced polymerization of glycidyl methacrylate (GMA) monomer. The factors affecting the degree of polymerization and yield (%) of PGMA such as type of solvent, monomer concentration, and irradiation dose were investigated. It was found that the PGMA yield (%) increases with increasing monomer concentration up to 50% and absorbed dose of 5 kGy. The resulting PGMA containing the epoxy group was chemically modified by hydroxyl amine to act as anion-exchange resin for uptake of {sup 131}I{sup -} ions. The modified PGMA (MPGMA) was characterized by Fourier transform infrared (FT-IR) spectrophotometer, thermal gravimetric analysis (TGA) and scanning electron microscopy (SEM). I-131 is produced from the fission of U-235 with low-enrichment uranium (LEU) targets in the Egyptian Second Research Reactor (ETRR-2). Separation of iodide from the radioactive solution by batchwise and column techniques was employed to determine the adsorption capacity of the MPGMA. Quality control of {sup 131}I product solution and radiochemical purity was examined by using the ascending paper chromatography method. The uptake behavior of MPGMA towards {sup 131}I{sup -} ions were studied at different experimental conditions and achieved by X-ray fluorescence (XRF). The synthesized MPGMA showed good results as anion-exchange and an effective adsorbent for uptaking {sup 131}I{sup -} ions.

Ponderosa pine resin defenses and growth: metrics matter.

Science.gov (United States)

Hood, Sharon; Sala, Anna

2015-11-01

Bark beetles (Coleoptera: Curculionidae, Scolytinae) cause widespread tree mortality in coniferous forests worldwide. Constitutive and induced host defenses are important factors in an individual tree's ability to survive an attack and in bottom-up regulation of bark beetle population dynamics, yet quantifying defense levels is often difficult. For example, in Pinus spp., resin flow is important for resistance to bark beetles but is extremely variable among individuals and within a season. While resin is produced and stored in resin ducts, the specific resin duct metrics that best correlate with resin flow remain unclear. The ability and timing of some pine species to produce induced resin is also not well understood. We investigated (i) the relationships between ponderosa pine (Pinus ponderosa Lawson & C. Lawson) resin flow and axial resin duct characteristics, tree growth and physiological variables, and (ii) if mechanical wounding induces ponderosa pine resin flow and resin ducts in the absence of bark beetles. Resin flow increased later in the growing season under moderate water stress and was highest in faster growing trees. The best predictors of resin flow were nonstandardized measures of resin ducts, resin duct size and total resin duct area, both of which increased with tree growth. However, while faster growing trees tended to produce more resin, models of resin flow using only tree growth were not statistically significant. Further, the standardized measures of resin ducts, density and duct area relative to xylem area, decreased with tree growth rate, indicating that slower growing trees invested more in resin duct defenses per unit area of radial growth, despite a tendency to produce less resin overall. We also found that mechanical wounding induced ponderosa pine defenses, but this response was slow. Resin flow increased after 28 days, and resin duct production did not increase until the following year. These slow induced responses may allow

Preparation and characterization of ZnO-PMMA resin nanocomposites for denture bases.

Science.gov (United States)

Cierech, Mariusz; Wojnarowicz, Jacek; Szmigiel, Dariusz; Bączkowski, Bohdan; Grudniak, Anna Maria; Wolska, Krystyna Izabela; Łojkowski, Witold; Mierzwińska-Nastalska, Elżbieta

2016-01-01

The aim of the paper was to investigate the antifungal activity of zinc oxide nanoparticles (ZnONPs) against Candida albicans. Some attempts have been made to find out the best way to introduce ZnONPs into polymethyl methacrylate (PMMA) resin material and to determine some parameters of a newly formed composite. Zinc oxide nanoparticles were manufactured and their basic physical parameters were determined (average particle size, density, specific surface area). Minimal inhibitory concentration (MIC) of ZnONPs was determined for the Candida albicans standard strain. The average size of ZnO conglomerates in the monomer solution of PMMA resin was measured using a dynamic light scattering instrument. PMMA resin samples with incorporated ZnONPs were produced. The morphology of nanopowder and the newly formed composite was examined under a scanning electron microscope (SEM). In addition, the roughness parameter of PMMA resin material was investigated before and after ZnONPs modification. Nanopowder with the average particle size of 30 nm, density of 5.24 g/cm3 and surface area of 39 m2/g was obtained. MIC was determined at the level of 0.75 mg/mL. The average size of ZnO conglomerates in the monomer solution of acrylic resin dropped by 11 times after ultrasound activation. SEM examination of a newly formed composite showed a successful introduction of ZnONPs confirmed by the energy dispersive X-ray spectroscopy (EDS) analysis. There were no statistically significant differences in the biomaterial roughness before and after the modification of ZnONPs. Zinc oxide nanoparticles were successfully incorporated into acrylic resin used for the production of denture bases. The presence of nanoparticles with sizes below 100 nm was confirmed. Nevertheless a newly created composite needs to be further investigated to improve its homogeneity, and to check its microbiological properties, strength and biocompatibility prior to its possible clinical use.

Influence of oligomeric resins on traction and rolling resistance of silica tire treads

NARCIS (Netherlands)

Vleugels, N.; Pille-Wolf, W.; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.

2016-01-01

This study concerns the silica-reinforcement of synthetic rubber compounds for passenger tire treads with the objective to gain insight into the beneficial effects of oligomeric resins, derived from natural and synthetic monomers, on the major tire performance factors: rolling resistance and (wet)

Influence of oligomeric resins on traction and rolling resistance of silica tire treads

NARCIS (Netherlands)

Vleugels, N.; Pille-Wolf, W.; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.

2013-01-01

This study concerns the silica-reinforcement of synthetic rubber compounds for passenger tire treads with the objective to gain insight into the beneficial effects of oligomeric resins, derived from natural and synthetic monomers, on the major tire performance factors: Rolling Resistance and (Wet)

Development of radiation curable surface coating based on soybean oil. part II: Evaluation of the prepared acrylated resin as surface coatings by using EB or UV sources for radiation curing applications

International Nuclear Information System (INIS)

Ibrahim, M.S.; Said, H.M.; Moussa, I.M.

2005-01-01

In recent years, there has been a growing trend in using vegetable oils as raw materials in acylation production that can be cured by UV/EB systems. The acrylated resin formulates by using individually different functional acrylate monomers were prepared and cured by EB or UV sources. The characterization properties of the cured films were investigated in terms of pendulum hardness, bending, impact, gloss, adhesion and chemical tests. Other formulations were prepared by mixing a constant ratio of different functional acrylate monomers and exposed to UV or EB irradiation. The results showed that the hardness of cured films were increased by increasing the functionality of monomers with excellent adhesion for all formulations but at expense of other properties involving bending and impact tests. Therefore, it can be deduce that the hardness of the curing surface coating by using EB was found to be nearly twice the hardness of the curing surface coating by using UV irradiation. Also, the best formulations which have given good chemical and mechanical properties are (mono-di) functional acrylate monomer resin under EB and (mono-tri) functional acrylate monomer resin under UV irradiation

Radiation hardening lacquer binding agent based on a polyester resin with at least 3.5 double links pr. 1000 molecular weight units

International Nuclear Information System (INIS)

Crimlisk, D.J.; Wright, A.; Groves, T.E.

1976-01-01

The binding agent is suitable for hardening by electrons with an energy of between 100,000 and 500,000eV. It consists mainly of a solution of a polyester resin with at least 3.5 double links per 1000 mol, in an olefine-unsaturated monomer. The molecular weight of the polyester is between 800 and 1100 and the ratio of the number of double links in the monomer to that in the resin (degree of unsaturation) is in the range 0.75-2.0, or more specifically, between 1 and 1.5. Cellulose acetate/butyrate (CAB) and/or a butylated melamine/formaldehyde resin may be added to improve the surface properties. Likewise from 0.1 to 0.5% polyethylene wax may be added to give a better surface finish and hardness. (JIW)

Measurements of volatile compound contents in resins using a moisture analyzer.

Science.gov (United States)

Hashimoto, Masanori; Nagano, Futami; Endo, Kazuhiko; Ohno, Hiroki

2010-02-01

The contents of volatile adhesive compounds, such as water, solvents, and residual unpolymerized monomers, affect the integrity and durability of adhesive bonding. However, there is no method available that can be used to rapidly assess the residual solvent or water contents of adhesive resins. This study examined the effectiveness of a digital moisture analyzer to measure the volatile compound contents of resins. Five self-etching adhesives and seven experimental light-cured resins prepared with different contents (0, 10, and 20% by weight) of water or solvents (acetone and ethanol) were examined in this study. The resins were prepared using different methods (with and without air blast or light-curing) to simulate the clinical conditions of adhesive application. Resin weight changes (% of weight loss) were determined as the residual volatile compound contents, using the moisture analyzer. After the measurements, the resin films were examined using a scanning electron microscope. The weight changes of the resins were found to depend on the amount of water or solvents evaporating from the resin. Water and solvents were evaporated by air blast or light-curing, but some of the water and solvents remained in the cured resin. The moisture analyzer is easy to operate and is a useful instrument for using to measure the residual volatile compound contents of adhesive resin.

The Continuation Study of the Measurement of Residual Monomer from theDenture Base After Three Month Worn by Gas Chromatography on the Radiationand Non Radiation Worker

International Nuclear Information System (INIS)

Isyuniarto; Winoto

2000-01-01

Residual monomer measurement on the radiation and non radiation workerafter three month worn the denture has been done. The aim of the research isto investigated residual monomer concentration on after three month worn. Thedenture base material, made of resin acrylic, sometimes is cause mucosairritation in the mouth, and dental irritation or allergic reaction, becauseof residual monomer that left on the mouth cavity. In this research two groupwere needed there are the radiation and non radiation worker, the level ofthe residual monomer count by gas chromatography analysis. The result of thisresearch showed that the level of residual monomer of two group are same orthere have same level of the limit value. The measurement result is in therange of 0.1783 ± 0.011 mg/l to 0.1790 ± 0.004 mg/l. (author)

Structure–property relationships in hybrid dental nanocomposite resins containing monofunctional and multifunctional polyhedral oligomeric silsesquioxanes

Directory of Open Access Journals (Sweden)

Wang WG

2014-02-01

Full Text Available Weiguo Wang,1,* Xiang Sun,1,* Li Huang,2,* Yu Gao,1 Jinghao Ban,1 Lijuan Shen,1 Jihua Chen1 1Department of Prosthodontics, 2Department of General Dentistry and Emergency, School of Stomatology, Fourth Military Medical University, Xi'an, People's Republic of China*These authors contributed equally to this workAbstract: Organic-inorganic hybrid materials, such as polyhedral oligomeric silsesquioxanes (POSS, have the potential to improve the mechanical properties of the methacrylate-based composites and resins used in dentistry. In this article, nanocomposites of methacryl isobutyl POSS (MI-POSS [bears only one methacrylate functional group] and methacryl POSS (MA-POSS [bears eight methacrylate functional groups] were investigated to determine the effect of structures on the properties of dental resin. The structures of the POSS-containing networks were determined by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Monofunctional POSS showed a strong tendency toward aggregation and crystallization, while multifunctional POSS showed higher miscibility with the dimethacrylate monomer. The mechanical properties and wear resistance decreased with increasing amounts of MI-POSS, indicating that the MI-POSS agglomerates act as the mechanical weak point in the dental resins. The addition of small amounts of MA-POSS improved the mechanical and shrinkage properties. However, samples with a higher MA-POSS concentration showed lower flexural strength and flexural modulus, indicating that there is a limited range in which the reinforcement properties of MA-POSS can operate. This concentration dependence is attributed to phase separation at higher concentrations of POSS, which affects the structural integrity, and thus, the mechanical and shrinkage properties of the dental resin. Our results show that resin with 3% MA-POSS is a potential candidate for resin-based dental materials

Efecto de surfactantes polimerizables en la distribución de tamaño de partícula, pH, viscosidad, contenidos de sólidos y de monómero residual de una resina estireno-butilacrilato Effect of polymerizable surfactants on particle size distribution, pH, viscosity, contents of solids and residual monomer of a styrene-butylacrylate resin

Directory of Open Access Journals (Sweden)

Luis A. Rios

2013-01-01

Full Text Available Se presentan los resultados de la polimerización en emulsión de una resina acrílica estirenada usando surfactantes polimerizables, los cuales presentan ventajas técnicas como baja formación de espuma, alta resistencia de la película al contacto con agua y buena estabilidad en la polimerización. Se evaluó el efecto de estos surfactantes polimerizables en la distribución de tamaños de partícula de la resina; además se determinaron propiedades finales de la resina tales como porcentaje de sólidos, porcentaje de monómero libre, viscosidad y pH. Estos resultados se compararon con los obtenidos usando surfactantes convencionales no polimerizables del tipo alquil fenol etoxilado y alquilarilpoliglicol éter sulfato de sodio. Los resultados indican que que se pueden remplazar totalmente los surfactantes convencionales no polimerizables por los surfactantes poliméricos evaluados sin afectar significativamente las propiedades de la resina, mientras que la sustitución parcial de los surfactantes no polimerizables por los polimerizables induce, en algunos casos, a la formación de partículas con mayor tamaño a las presentes en la muestra estándar.Results on the emulsion polymerization of a styrenated acrylic resin using polymerizable surfactants are presented. These surfactants exhibit low foaming, high film strength upon contact with water and good stability in the polymerization. A comparison was made with results for conventional non-polymerizable alkyl aryl polyglycol ether sulphate, sodium salt and nonylphenolethoxylate surfactants. The effect of these polymerizable surfactants on the particle size distribution of the resin was evaluated; in addition to determining the final properties of the resin such as solids content, free monomer content, viscosity and pH. It is feasible to totally replace non-polymerizable surfactants by the polymerizable surfactants evaluated without affecting significantly the properties of the resin, while

Radiation Induced Grafting of Acrylate onto Waste Rubber: The Effect of Monomer Type

Directory of Open Access Journals (Sweden)

Shirajuddin Siti Salwa M.

2017-01-01

Full Text Available The effect of three different acrylate group monomers, namely n-butyl acrylate, methacrylic acid and tripropylene glycol diacrylate of radiation induced grafting onto waste rubber was studied. The electron beam accelerator operated at voltage of 2MeV was used to irradiate the waste rubber at 10 kGy and 100 kGy absorbed radiation dose, respectively. The formation of grafting was observed from the increase in the grafting yield and confirmed by Transformed Infra-Red Spectroscopy results. According to the result obtained, only tripropylene glycol diacrylate was selected to graft onto waste rubber. The carbonyl bond from acrylate groups was seen at 1726 cm-1 band which confirmed the presence of TPGDA in the polymer matrix. This indicates the successful preparation of the TPGDA-grafted waste rubber via radiation induced grafting techniques.

Radiation-induced crosslinking of polyethylene in the presence of bifunctional vinyl monomers

Energy Technology Data Exchange (ETDEWEB)

Joshi, M.S.

1976-10-06

The apparent crosslinking produced by the radiation grafting of two monomers to polyethylene, acrylic acid and acrylonitrile, was investigated. Evidence is presented to show that covalent crosslinks are not produced during the radiation grafting step; covalent crosslinks are produced by the post-irradiation heat treatment associated with measurements of gel; the enhancement in gel fraction and physical properties arises from true crosslinks rather than chain entanglements; and there may be practical value associated with the sensitization of crosslinking produced by the methods employed in this work. The effect of monomer-solvent composition on the graft and gel yield was studied. Viscoelastic properties of grafted films were determined above the melting point of pure polyethylene. The kinetic data, infrared spectra, and viscoelastic properties are the bases for the following mechanism: (1) Acrylic acid-g-PE: Acrylic acid enters the film in the form of a hydrogen bonded dimer and undergoes a grafting reaction that produces hydrogen-bond crosslinks. The heat treatment during the conventional methods for determining of crosslinks convert them into intermolecular anhydride bonds. (2) Acrylonitrile-g-PE: In this, the post-grafting crosslinking is the result of a thermally induced chain reaction leading to an uninterrupted conjugated sequence. The length of the ring structure increases with time and temperature, and the intensity of color increases with the length of the ring structure.

Radiation-induced crosslinking of polyethylene in the presence of bifunctional vinyl monomers

International Nuclear Information System (INIS)

Joshi, M.S.

1976-01-01

The apparent crosslinking produced by the radiation grafting of two monomers to polyethylene, acrylic acid and acrylonitrile, was investigated. Evidence is presented to show that covalent crosslinks are not produced during the radiation grafting step; covalent crosslinks are produced by the post-irradiation heat treatment associated with measurements of gel; the enhancement in gel fraction and physical properties arises from true crosslinks rather than chain entanglements; and there may be practical value associated with the sensitization of crosslinking produced by the methods employed in this work. The effect of monomer-solvent composition on the graft and gel yield was studied. Viscoelastic properties of grafted films were determined above the melting point of pure polyethylene. The kinetic data, infrared spectra, and viscoelastic properties are the bases for the following mechanism: (1) Acrylic acid-g-PE: Acrylic acid enters the film in the form of a hydrogen bonded dimer and undergoes a grafting reaction that produces hydrogen-bond crosslinks. The heat treatment during the conventional methods for determining of crosslinks convert them into intermolecular anhydride bonds. (2) Acrylonitrile-g-PE: In this, the post-grafting crosslinking is the result of a thermally induced chain reaction leading to an uninterrupted conjugated sequence. The length of the ring structure increases with time and temperature, and the intensity of color increases with the length of the ring structure

Polymerization shrinkage kinetics and shrinkage-stress in dental resin-composites.

Science.gov (United States)

Al Sunbul, Hanan; Silikas, Nick; Watts, David C

2016-08-01

To investigate a set of resin-composites and the effect of their composition on polymerization shrinkage strain and strain kinetics, shrinkage stress and the apparent elastic modulus. Eighteen commercially available resin-composites were investigated. Three specimens (n=3) were made per material and light-cured with an LED unit (1200mW/cm(2)) for 20s. The bonded-disk method was used to measure the shrinkage strain and Bioman shrinkage stress instrument was used to measure shrinkage stress. The shrinkage strain kinetics at 23°C was monitored for 60min. Maximum strain and stress was evaluated at 60min. The shrinkage strain rate was calculated using numerical differentiation. The shrinkage strain values ranged from 1.83 (0.09) % for Tetric Evoceram (TEC) to 4.68 (0.04) % for Beautifil flow plus (BFP). The shrinkage strain rate ranged from 0.11 (0.01%s(-1)) for Gaenial posterior (GA-P) to 0.59 (0.07) %s(-1) for BFP. Shrinkage stress values ranged from 3.94 (0.40)MPa for TET to 10.45 (0.41)MPa for BFP. The apparent elastic modulus ranged from 153.56 (18.7)MPa for Ever X posterior (EVX) to 277.34 (25.5) MPa for Grandio SO heavy flow (GSO). The nature of the monomer system determines the amount of the bulk contraction that occurs during polymerization and the resultant stress. Higher values of shrinkage strain and stress were demonstrated by the investigated flowable materials. The bulk-fill materials showed comparable result when compared to the traditional resin-composites. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

[Chinese medicinal monomer and compound for 60Co-gamma-induced spermatogenic disturbance in mice].

Science.gov (United States)

Zhang, Wei-xing; Wang, Hua-li; Wang, Rui; Li, Rui; He, Wei; Zhang, Tian-biao

2010-05-01

To explore the effects of the monomer and compound of the Chinese herbal drugs resveratrol, lycium barbarum polysaccharide (LBP) and icariin on 60Co-gamma-induced spermatogenic disturbance in mice based on the theory of modern Chinese medicine. A total of 105 male Kunming mice were randomly divided into seven groups, with 15 in each. Group A were normally raised and Groups B, C, D, E, F and G irradiated by 60Co-gamma 6 Gy followed by 60Co-gamma 4 Gy at the interval of 7 days. A week later, Groups C, D, E, F and G received intragastrically the suspension of resveratrol, resveratrol + LBP, resveratrol + icariin, resveratrol + LBP + icariin and resveratrol + LBP + icariin + L-carnitine, respectively, at the dose of 80 mg/(kg x d) for 60 days. The general condition, physical signs and body weight changes of the mice were recorded, and 24 hours after the intragastric medication, their testes were harvested to obtain the testicular weight and indexes, the levels of FSH, LH, T and E2 determined by ELISA, the T/E2 ratio calculated, and the histology of the testis tissues observed under the microscope. The testicular indexes of the mice were decreased by radiation-induced damage, but restored to some extent after intragastric medication, especially in Groups E, F and G. The levels of FSH, LH and T were obviously improved by LBP. The T level and testis weight were increased by Icariin. The level of T/E2 was elevated in Groups E, F and G. The best results were achieved in Group F, which exhibited almost complete recovery from reproductive endocrine disorder and spermatogenic damage. The Chinese medicinal monomer is effective for 60Co-gamma-induced spermatogenic disturbance in mice, and the compound suspension of resveratrol + LBP + icariin produces the best result.

Vinyl ester resin and process for curing same with ionizing radiation in the presence of amines

International Nuclear Information System (INIS)

Mani, I.

1975-01-01

The addition of about 2 to 5 weight percent of certain amines to a thermosettable mixture of certain vinyl monomers and a polymerizable vinyl ester resin reduces the dosage level of ionizing radiation required to cure the mixture. (U.S.)

TUNG OIL BASED MONOMER FOR THERMOSETTING POLYMERS: SYNTHESIS, CHARACTERIZATION AND COPOLYMERIZATION WITH STYRENE

Directory of Open Access Journals (Sweden)

Chengguo Liu,

2011-11-01

Full Text Available A tung oil (TO based monomer for rigid thermosetting polymer was synthesized, characterized, and copolymerized with styrene in this study. Tung oil was alcoholyzed with pentaerythritol (PER to get tung oil pentaerythritol alcoholysis products (TOPER, and the optimized conditions were explored according to the yields of TOPER analyzed by gas chromatography-mass spectrometry (GC-MS. The resulting alcoholysis products were maleinated to form tung oil maleate half ester (TOPERMA, and the reaction conditions were determined by monitoring the reaction extents of TOPER and maleic anhydride (MA with 1HNMR spectroscopy. The TO alcoholysis and maleinization reaction products were characterized by IR, 1HNMR, and electrospray ionization-mass spectrometry (ESI-MS techniques. At last, the TOPERMA mixture was cured with styrene (St, and the initiator tert-butyl peroxy benzoate (TPB. Differential scanning calorimetry (DSC was employed to characterize the curing process. Mechanical properties of the cured TOPERMA/St resin further confirmed the best procedure for the maleinization reaction. The loading of TO reached about 30% weight of the resulting thermosetting polymer. This promising material from renewable resources can be a potential substitution for petroleum products when used as sheet molding compounds.

Casting of organic glass by radiation-induced polymerization of glass-forming monomers at low temperature. II. Optical strain of remaining stress type

International Nuclear Information System (INIS)

Okubo, H.; Yoshii, F.; Kaetsu, I.; Honda, S.

1978-01-01

Previously it was found that casting could be carried out efficiently without strain formation by radiation-induced polymerization of glass-forming monomers. Two types of strain were observed in casting: thermal stream type, which was studied previously, and remained stress type. In this report, the effect of various factors on the formation of remaining stress-type strain in radiation-induced casting polymerization was studied. It was found that the molecular weight of prepolymer did not affect strain formation, while prepolymer concentration and viscosity of the system had a serious influence on strain formation. It could be deduced that this type of strain formed as a result of remaining inner stress due to poor relaxation of the shrinking stress. It was realized that less volume shrinkage of glass-forming monomers accompanying casting polymerization reduced the strain formation of this type in radiation-induced casting polymerization at low temperatures

Vinyl ester resin and process for curing same with ionizing radiation in the presence of amines

International Nuclear Information System (INIS)

Mani, I.

1975-01-01

The addition of about 1.5 to 5 weight percent of certain amines to a thermosettable mixture of an alkenyl aromatic monomer and a polymerizable vinyl ester resin reduces the dosage level of ionizing radiation required to cure the mixture. (U.S.)

Vegetable oil-derived epoxy monomers and polymer blends: A comparative study with review

Directory of Open Access Journals (Sweden)

T. P. Schuman

2013-03-01

Full Text Available Glycidyl esters of epoxidized fatty acids derived from soybean oil (EGS and linseed oil (EGL have been synthesized to have higher oxirane content, more reactivity and lower viscosity than epoxidized soybean oil (ESO or epoxidized linseed oil (ELO. The EGS and ESO, for comparison, were used neat and in blends with diglycidyl ether of bisphenol A (DGEBA. Thermosetting resins were fabricated with the epoxy monomers and either BF3 catalyst or anhydride. The curing behaviors, glass transition temperatures, crosslink densities and mechanical properties were tested. The results indicated that polymer glass transition temperatures were mostly a function of oxirane content with additional influence of glycidyl versus internal oxirane reactivity, pendant chain content, and chemical structure and presence of saturated components. EGS provided better compatibility with DGEBA, improved intermolecular crosslinking and glass transition temperature, and yielded mechanically stronger polymerized materials than materials obtained using ESO. Other benefits of the EGS resin blend systems were significantly reduced viscosities compared to either DGEBA or ESO-blended DGEBA counterparts. Therefore, EGS that is derived from renewable sources has improved potential for fabrication of structural and structurally complex epoxy composites, e.g., by vacuum-assisted resin transfer molding.

Kinetics of Waterborne Alkyd/Acrylic Hybrid Resin Free Radical Polymerization by Two Systems of Redox and Thermal Initiators

OpenAIRE

shirin Madadi; ali akbar Yousefi; elham Keshmirizadeh

2012-01-01

Kinetics of radical polymerizations of waterborne alkyd/acrylic hybrid resin via batch mini-emulsion technique was studied using redox initiators (TBHP/Fe2+/EDTA/AsAc  and  TBHP/Fe2+/EDTA/SFS) at relatively low temperatures and thermal initiators (BPO, KPS and AIBN) at higher temperatures to seek the most suitable initiator system. At the end of all reactions the unreacted monomer content was reduced using post-polymerization technique; consequently, leading to increased monomer conversion an...

MICROWAVE INDUCED DEGRADATION OF GLASS FIBER REINFORCED POLYESTER FOR FIBER AND RESIN RECOVERY

DEFF Research Database (Denmark)

Ucar, Hülya; Nielsen, Rudi Pankratz; Søgaard, Erik Gydesen

A solvolysis process to depolymerize the resin in glass fiber reinforced composites and recover the glass fibers has been investigated using microwave induced irradiation. The depolymerization was carried out in HNO3 with concentrations in the range of 1M-7M and in KOH with concentrations ranging...

Sustainable Poly(Ionic Liquids) for CO2 Capture Based on Deep Eutectic Monomers

KAUST Repository

Isik, Mehmet; Zulfiqar, Sonia; Edhaim, Fatimah; Ruiperez, Fernando; Rothenberger, Alexander; Mecerreyes, David

2016-01-01

The design of high performance solid sorbent materials for CO2 capture is a technology which has been employed to mitigate global warming. However, the covalent incorporation of functionalities into polymeric supports usually involves multistep energy-intensive chemical processes. This fact makes the net CO2 balance of the materials negative even though they possess good properties as CO2 sorbents. Here we show a new family of polymers which are based on amines, amidoximes, and natural carboxylic acids and can be obtained using sustainable low energy processes. Thus, deep eutectic monomers based on natural carboxylic acids, amidoximes, and amines have been prepared by just mixing with cholinium type methacrylic ammonium monomer. The formation of deep eutectic monomers was confirmed by differential scanning calorimetry measurements. In all cases, the monomers displayed glass transition temperatures well below room temperature. Computational studies revealed that the formation of eutectic complexes lengthens the distance between the cation and the anion causing charge delocalization. The liquid nature of the resulting deep eutectic monomers (DEMs) made it possible to conduct a fast photopolymerization process to obtain the corresponding poly(ionic liquids). Materials were characterized by means of nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction to evaluate the properties of the polymers. The polymers were then used as solid sorbents for CO2 capture. It has been shown that the polymers prepared with citric acid displayed better performance both experimentally and computationally. The current endeavor showed that sustainable poly(ionic liquids) based on deep eutectic monomers can be easily prepared to produce low-energy-cost alternatives to the materials currently being researched for CO2 capture. © 2016 American Chemical Society.

Sustainable Poly(Ionic Liquids) for CO2 Capture Based on Deep Eutectic Monomers

KAUST Repository

Isik, Mehmet

2016-10-05

The design of high performance solid sorbent materials for CO2 capture is a technology which has been employed to mitigate global warming. However, the covalent incorporation of functionalities into polymeric supports usually involves multistep energy-intensive chemical processes. This fact makes the net CO2 balance of the materials negative even though they possess good properties as CO2 sorbents. Here we show a new family of polymers which are based on amines, amidoximes, and natural carboxylic acids and can be obtained using sustainable low energy processes. Thus, deep eutectic monomers based on natural carboxylic acids, amidoximes, and amines have been prepared by just mixing with cholinium type methacrylic ammonium monomer. The formation of deep eutectic monomers was confirmed by differential scanning calorimetry measurements. In all cases, the monomers displayed glass transition temperatures well below room temperature. Computational studies revealed that the formation of eutectic complexes lengthens the distance between the cation and the anion causing charge delocalization. The liquid nature of the resulting deep eutectic monomers (DEMs) made it possible to conduct a fast photopolymerization process to obtain the corresponding poly(ionic liquids). Materials were characterized by means of nuclear magnetic resonance, differential scanning calorimetry, thermogravimetric analysis, and X-ray diffraction to evaluate the properties of the polymers. The polymers were then used as solid sorbents for CO2 capture. It has been shown that the polymers prepared with citric acid displayed better performance both experimentally and computationally. The current endeavor showed that sustainable poly(ionic liquids) based on deep eutectic monomers can be easily prepared to produce low-energy-cost alternatives to the materials currently being researched for CO2 capture. © 2016 American Chemical Society.

Synthesis of hemicellulose-acrylic acid graft copolymer super water absorbent resin by ultrasonic irradiation technology

Directory of Open Access Journals (Sweden)

Fangfang LIU

2015-12-01

Full Text Available The hemicellulose super water absorbent resin is prepared by using ultrasonic irradiation technology, with the waste liquid produced during the preparation of viscose fiber which contains a large amount of hemicellulose as raw material, acrylic acid as graft monomer, N,N’-methylene bis acrylamide (NMBA as cross linking agent, and (NH42S2O8-NaHSO3 as the redox initiation system. The synthesis conditions, structure and water absorption ability of resin are discussed. The results indicate that water absorbency of the resin is 311 g/g, the tap water absorbency is 102 g/g, the normal saline absorbency is 55 g/g, and the artificial urine absorbency is 31 g/g under the optimal synthesis conditions, so the resin has great water absorption rate and water retaining capacity. The FT-IR and SEM analysis shows that the resin with honeycomb network structure is prepared. The successfully synthesized of the resin means that the hemicellulose waste liquid can be highly effectively recycled, and it provides a kind of new raw material for the synthesis of super water absorbent resin.

Kinetics characterization of a novel photopolymerizable siloxane-modified acrylic resin

International Nuclear Information System (INIS)

Corcione, C. Esposito; Previderio, A.; Frigione, M.

2010-01-01

An experimental study was carried out for the development and characterization of innovative photopolymerizable siloxane-modified acrylic formulations for possible use as protective coatings. The kinetics of the radical photopolymerization mechanism induced by UV and visible radiations in presence of suitable photoinitiators was studied by a calorimetric analysis by varying the testing conditions (temperature, light power emission, atmosphere). The reactivity, expressed in terms of both heat developed and rate of reaction, was generally found to decrease when the photopolymerization was carried out in air, due the inhibiting action of the oxygen towards the free-radical polymerization. The addition of both a silane coupling agent or a high molecular weight polysiloxane monomer to the acrylic resin was found to reduce the heat of reaction. Experimental data were fitted to a kinetic model to quantify the effects of light intensity and temperature on reaction rates and extent of reaction. A good agreement between the experimental data and the theoretical model was generally found.

Effect of functional monomers in all-in-one adhesive systems on formation of enamel/dentin acid-base resistant zone.

Science.gov (United States)

Nikaido, Toru; Ichikawa, Chiaki; Li, Na; Takagaki, Tomohiro; Sadr, Alireza; Yoshida, Yasuhiro; Suzuki, Kazuomi; Tagami, Junji

2011-01-01

This study aimed at evaluating the effect of functional monomers in all-in-one adhesive systems on formation of acid-base resistant zone (ABRZ) in enamel and dentin. Experimental adhesive systems containing one of three functional monomers; MDP, 3D-SR and 4-META were applied to enamel or dentin surface and light-cured. A universal resin composite was then placed. The specimens were subjected to a demineralizing solution (pH 4.5) and 5% NaClO for acid-base challenge and then observed by SEM. The ABRZ was clearly observed in both enamel and dentin interfaces. However, enamel ABRZ was thinner than dentin ABRZ in all adhesives. Morphology of the ABRZ was different between enamel and dentin, and also among the adhesives. Funnel-shaped erosion was observed only in the enamel specimen with the 4-META adhesive. The formation of enamel/dentin ABRZ was confirmed in all adhesives, but the morphology was influenced by the functional monomers.

PETI-298 Prepared by Microwave Synthesis: Neat Resin and Composite Properties

Science.gov (United States)

Smith, Joseph G.; Connell, John W.; Li, Chao-Jun; Wu, Wei; Criss, Jim M., Jr.

2004-01-01

PETI-298 is a high temperature/high performance matrix resin that is processable into composites by resin transfer molding (RTM), resin infusion and vacuum assisted RTM techniques. It is typically synthesized in a polar aprotic solvent from the reaction of an aromatic anhydride and a combination of diamines and endcapped with phenylethynylphthalic anhydride. Microwave synthesis of PETI-298 was investigated as a means to eliminate solvent and decrease reaction time. The monomers were manually mixed and placed in a microwave oven for various times to determine optimum reaction conditions. The synthetic process was subsequently scaled-up to 330g. Three batches were synthesized and combined to give 1 kg of material that was characterized for thermal and rheological properties and compared to PETI-298 prepared by the classic solution based synthetic method. The microwave synthesized PETI-298 was subsequently used to fabricate flat laminates on T650 carbon fabric by RTM. The composite panels were analyzed and mechanical properties determined and compared with those fabricated from PETI-298 prepared by the classic solution method. The microwave synthesis process and characterization of neat resin and carbon fiber reinforced composites fabricated by RTM will be presented. KEY WORDS: Resin Transfer Molding, High Temperature Polymers, Phenylethynyl Terminated Imides, Microwave Synthesis

Biocompatibility of acrylic resin after being soaked in sodium hypochlorite

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Nike Hendrijatini

2009-06-01

Full Text Available Background: Acrylic resin as basic material for denture will stay on oral mucosa for a very long time. The polymerization of acrylic resin can be performed by conventional method and microwave, both produce different residual monomer at different toxicity. Acrylic resin can absorb solution, porous and possibly absorb disinfectantt as well, that may have toxic reaction with the tissue. Sodium Hypochlorite as removable denture disinfectant can be expected to be biocompatible to human body. The problem is how biocompatible acrylic resin which has been processed by conventional method and microwave method after being soaked in sodium hypochlorite solution. Purpose: The aim of this study was to understand in vitro biocompatibility of acrylic resin which has polimerated by conventional method and microwave after being soaked in sodium hypochlorite using tissue culture. Methods: Four groups of acrylic resin plate were produced, the first group was acrylic resin plate with microwave polymeration and soaked in sodium hypochlorite, the second group was acrylic resin plate with microwave polymeration but not soaked, the thirdwas one with conventional method and soaked and the last group was one with conventional method but not soaked, and in 1 control group. Each group consists of 7 plates. Biocompatibility test was performed in-vitro on each material using fibroblast tissue culture (BHK-21 cell-line. Result: The percentage between living cells and dead cells from materials which was given acrylic plate was wounted. The data was analyzed statistically with T test. Conclusion: The average value of living cells is higher in acrylic resin poimerization using microwave method compared to conventional method, in both soaked and non soaked (by sodium hypochlorite group. This means that sodium hypochlorite 0.5% was biocompatible to the mouth mucosa as removable denture disinfectant for 10 minutes soaking and washing afterwards.

In situ polymerization of vinyl monomers in polyester yarns

International Nuclear Information System (INIS)

Avny, Y.; Rebenfeld, L.; Weigmann, H.D.

1978-01-01

The effects of a pretreatment of polyester (PET) yarns with a strongly interacting solvent such as dimethylformamide (DMF) on vinyl monomer incorporation were investigated. When the DMF pretreatment is carried out at high temperatures (above 120 0 C), the swollen PET structure is stabilized by solvent-induced secondary crystallization. This substrate is highly suitable for the incorporation of vinyl monomers. In situ polymerization of vinyl monomers in DMF-treated PET was investigated using chemical and γ-irradiation polymerization techniques, both in the presence and in the absence of excess monomer outside the PET fibers. When polymerization was carried out in a system in which a constant supply of free radicals was available from the outside of the PET fibers, lower initiator concentrations and smaller γ-irradiation doses were necessary. These results are attributed to a low efficiency of the initiator inside the PET fiber due to mobility restrictions. Water uptake and moisture regain of PET yarns containing poly(hydroxyethyl methacrylate) and poly(acrylic acid) were also investigated. When most of the vinyl polymer was inside the PET fiber, water absorption was limited. The changes in mechanical properties of the PET yarns resulting from the DMF pretreatment were partially reversed by in situ polymerization of vinyl monomers

Polymerization of epoxy resins studied by positron annihilation

Energy Technology Data Exchange (ETDEWEB)

Suzuki, T. [Radiation Science Center, High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Hayashi, T. [Fine Chemical Research Lab., Sumitomo Chemical, Tsukuba (Japan); Ito, Y. [Research Center for Nuclear Science and Technology, Univ. of Tokyo (Japan)

2001-04-01

Positron annihilation lifetime spectroscopy (PALS) has been applied to study polymerization of epoxy resins of cresole novolac with a hardener of phenol novolac. PALS uses positrons to probe the microstructure of a nanometer (nm) size. Using PALS polymerization can be followed through three states: powder (monomer), liquid and solid. PALS is a unique method for the detection of intermolecular spaces, hence polymerization was followed from the point of view of free spaces (inter-molecular spaces) between polymer networks. The glass transition temperature (T{sub g}) was determined from the temperature dependence of the positronium (Ps) lifetime. Although Tg determined by PALS is usually lower than that determined by a mechanical analysis (TMA), it was observed that T{sub g} approached the value determined by TMA after long curing. Ps can form bubbles in a liquid, and the surface tension of a mixture of the resin and the hardener was calculated from a simple empirical formula using the Ps lifetime; the resulting value is similar to that of the bisphenol-A epoxy resin. Gelation was observed as an increase in the intensity of Ps and a sharp decrease in the lifetime. (orig.)

Effect of repair resin type and surface treatment on the repair strength of heat-polymerized denture base resin.

Science.gov (United States)

Alkurt, Murat; Yeşil Duymuş, Zeynep; Gundogdu, Mustafa

2014-01-01

Acrylic resin denture fracture is common in prosthodontic practice. When fractured denture bases are repaired, recurrent fractures frequently occur at the repair surface interface or adjacent areas. The purpose of this study was to evaluate the effect of different surface treatments on the flexural strength of the acrylic resin denture base repaired with heat-polymerized acrylic resin, autopolymerizing resin, and light-polymerized acrylic resin. Ninety-six specimens of heat-polymerized acrylic resin were prepared according to the American Dental Association Specification No. 12 (65.0 × 10.0 × 2.5 mm) and sectioned into halves to create a repair gap (3.0 × 10 × 2.5 mm). The sectioned specimens were divided into 3 groups according to their repair materials. The specimens from each group were divided into 4 subgroups according to their surface treatments: a control group without any surface treatment; an experimental group treated with methyl methacrylate monomer (MMA group); an experimental group treated with airborne-particle abrasion with aluminum oxide particles of 250-μm particle size (abrasion group); and an experimental group treated with erbium:yttrium-aluminum-garnet laser (laser group). After the surface treatments, the 3 materials were placed into the repair gaps and then polymerized. After all of the specimens had been ground and polished, they were stored in distilled water at 37°C for 1 week and subjected to a 3-point bend test. Data were analyzed with a 2-way analysis of variance, and the Tukey honestly significant difference test was performed to identify significant differences (α=.05). The effects of the surface treatments and repair resins on the surface of the denture base resin were examined with scanning electron microscopy. Significant differences were found among the groups in terms of repair resin type (P<.001). All surface-treated specimens had higher flexural strength than controls, except the surface treated with the methyl

Gamma irradiation-induced modifications of resins found in nuclear waste embedding processes; Modifications induites par irradiation gamma dans les differentes resines rencontrees dans le traitement des dechets nucleaires

Energy Technology Data Exchange (ETDEWEB)

Allali, H [Faculte des Science et Techniques, Settat (Morocco); Debre, O; Lambert, M; Nsouli, B; Thomas, J P [Inst. de Physique Nucleaire, Lyon-1 Univ., 69 - Villeurbanne (France); Collaboration: IPN-Lyon, Laboratoire d` Etude des Materiaux Plastiques et des Biomateriaux, URA 507, UCBL, Agence Nationale pour la Gestion des Dechets Radiactifs

1999-12-31

The various resins involved in nuclear waste disposal are subject to gamma irradiation-induced modifications. From Time-of-Flight Mass Spectrometry of Secondary ions emitted under High Energy Projectiles bombardment (HSF-SIMS) of such materials the following results are obtained: the embedding epoxy resin DGEBA-DDM does not exhibit significant bulk changes in chemical structure, whatever the dose rate and irradiation medium (air or water), at least up to 2 MGy. However, oxidation processes are well observed at the very surface. Under the same conditions Ion exchange resins to be embedded are subjected to scissions of their functional sites, leading to fixed ion release. Dehydration under irradiation is observed pointing out the crucial role of water in ion transport outside of the material. (authors)

Do water based resins find their use in radiation cure applications?

International Nuclear Information System (INIS)

Ravijst, J.-P.

1995-01-01

There is an increasing demand for UV/EB formulation without monomers. Water dilutable oligomers offer one approach to formulations of this type. Several ways to use water as a primary means of reducing oligomer viscosities are reviewed. A number of new water dilutable acrylate resins were prepared having different functionalities and properties. Depending on the structure, viscosity decreases significantly by adding water. Good reactivity, solvent and water resistance were achieved after curing

Monomers capable of forming four hydrogen bridges and supramolecular polymers formed by copolymerization of these monomers with regular monomers

NARCIS (Netherlands)

2004-01-01

The invention relates to the synthesis of polymers containing self-complementary quadruple hydrogen groups by copolymerizing monomers containing a quadruple hydrogen bonding group with one or more monomers of choice. The resulting polymers show unique new characteristics due to the presence of

Acrylated Palm Oil Resins for Radiation (UV) Curing of Over Print Varnish (OPV)

International Nuclear Information System (INIS)

Norshamsul Arif; Mohd Hilmi Mahmood; Khairul Zaman Mohd Dahlan; Rosley Che Ismail; Flora Sim; Sharilla Muhammad Faizal

2010-01-01

The purpose of this project was to determine the effects of Acrylated Epoxidized Palm Oil (EPOLA) on a radiation (UV) curing Over Print Varnish (OPV) application. The initial target was to produce an environmentally friendly resin (non-VOC) and reduce the dependence on petroleum (hydrocarbon) based products which are more toxic. Toxicity was determined via Acute Oral Toxicity (LD50), OECD 401 and Acute Toxicity (Dermal), OECD 402 technique whilst the reactivity, chemical resistance and other physical properties were obtained from actual printing application test. The developed EPOLA resin was combined with acrylated monomers, photo initiator(s) and additives in typical OPV formulation before being chemically converted into protective glossy printed film under Ultra Violet (UV-C) light. The gloss, flexibility and adhesion effects are significantly greater than conventional OPV epoxy based coupled with further extremely low irritancy to skin. The contributions of this project are twofold. First, the toxicity of developed acrylated Palm Oil resin is certainly lower than conventional epoxy acrylates resin. Secondly, the benefits towards radiation curing OPV applications were significantly demonstrated. (author)

Synthesis of Poly (Butyl Methacrylate/Butyl Acrylate) Highly Absorptive Resin Using Glow Discharge Electrolysis

International Nuclear Information System (INIS)

Li Yan; Yao Mengqi; Liao Ruirui; Yang Wu; Gao Jinzhang; Ren Jie

2014-01-01

A highly absorptive resin poly (butyl methacrylate (BMA)-co-butyl acrylate (BA)) was prepared by emulsion polymerization, which was initiated by glow discharge electrolysis plasma (GDEP). The effects of discharge voltage, discharge time, monomer ratio and the amounts of cross-linking agent were examined and discussed in detail. The chemical structure of the obtained resin was characterized by means of attenuated total reflectance Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The optimal conditions were obtained as: discharge voltage was 600 V, discharge time was 8 min, the ratios of BMA:BA being 2:1 for chloroform and 3:1 for xylene, with 2% N, N'-methylenebis. Under optimal conditions, the oil absorbency was 70 g/g for chloroform and 46 g/g for xylene. Moreover, the absorptive dynamical behavior of the resulting resin was also investigated

Low-temperature radiation-induced polymerization of vinyl monomers in the crystal matrix of polydimethyl siloxane

International Nuclear Information System (INIS)

Mujdinov, M.R.; Kiryukhin, D.P.; Barkalov, I.M.; Gol'danskij, V.I.

1979-01-01

It is shown that in the process of the slow cooling of vinyl monomer solution in dimethyl siloxane rubber (SKT mark) crystallization of SKT takes place, at that, considerable part of vinyl monomers (up to 70 wt. % of rubber) is sorbed in the pores of crystal matrix and it does not form its proper crystal phase. Slight anomalies in heat capacity in the 120-140 K range, the melting of non-sorbed part of MA and the melting of SKT + MA ''complex'' have been observed on the calorimetric curve at the SKT - methylacrylate (MA) system heating. In the process of heating such samples, irradiated at 77 K by γ-rays of 60 Co, heat evolution connected with sorbed monomer polarization, has been observed starting from 125-130 K. In the 140-200 K range already before MA and SKT melting intense polymerization takes place, which results in practically full monomer consumption and formation of graft copolymer. Radiation-chemical yield of monomer reduction reaches G(-M) approximately equal to 2x10 5 molecules for 100 eV, radiation yield of postpolymerization of crystal MA does not exceed G(-M) approximately equal to 50 molecules for 100 eV

SYNTHESIS, THERMAL STUDIES AND CONVERSION DEGREE OF DIMETHACRYLATE POLYMERS USING NEW NON-TOXIC COINITIATORS

Directory of Open Access Journals (Sweden)

Rafael Turra Alarcon

Full Text Available The aim of this paper is to replace toxic coinitiators (tertiary amines by non-toxic compounds such as glycerol and inositol (polyalcohol in dimethacrylate resins. For this purpose, mid infrared spectroscopy (MIR was used to calculate the monomers' degree of conversion (%DC; as well as simultaneous Thermogravimetric Analysis – Differential Thermal Analysis (TGA-DTA and Differential Scanning Calorimetry (DSC were conducted to evaluate thermal stability, degradation steps, and thermal events. The use of different initiator systems did not modify the thermal events or the thermal stability of each of the dimethacrylate resins. Results show a substitution of system 2 (toxicity by system 3 (low toxicity, which had a good conversion velocity and total conversion in some monomers, is plausible.

Gamma ray induced electrical conductivity in bisphenol-A type epoxy resin and polyethylene terephthalate

International Nuclear Information System (INIS)

Maeda, Hideaki; Nakakita, Tsuneo

1978-01-01

The insulation materials to support magnets for nuclear fusion reactors are exposed to high energy neutron beam and the gamma ray due to the accompanying induced radio activity through blankets or radiation shields. In such materials, radiation-induced conduction (RIC) is a problem, which occurs due to the charged particles generated in the insulation materials during irradiation. As one of such materials, use of epoxy composite material is expected, but its RIC has been scarcely measured. An approach to measure the wave form of transient current (or electric charge) caused by irradiating the radiation pulses of nano-second order to the materials has been developed. This paper reports the results of having measured RIC in bisphenol-A type epoxy resin at the electric field from 1 x 10 4 to 3 x 10 5 V/cm and γ dose rate from 9 x 10 3 to 9 x 10 5 R/h over the temperature range of -170 deg. C to +110 deg. C. The RIC of polyethylene terephthalate (PET) was also measured in the same regions, whose molecular structure is comparatively similar to the bisphenol-A type epoxy resin, and of which the fundamental processes for RIC have been clarified pretty well. The radiation sources of 4.3 kCi 60 Co of NAIG and 45 kCi 60 Co of JAERI were used. The experimental circuits and the cryostat are described, then as for the results, explanation and discussion are given to the characteristics of induced current, dependence on dose rate and dependence on temperature of RIC conductivity. The process of capturing carrier in deep traps seems to be dominant in the bisphenol-A type epoxy resin, similarly to that of PET. (Wakatsuki, Y.)

Effects of monomer shape on the formation of aggregates from a power law monomer distribution

International Nuclear Information System (INIS)

Perry, J; Kimery, J; Matthews, L S; Hyde, T W

2013-01-01

The coagulation of dust aggregates is an important process in many physical systems such as the Earth's upper atmosphere, comet tails and protoplanetary discs. Numerical models which study the aggregation in these systems typically involve spherical monomers. There is evidence, however, via the polarization of sunlight in the interstellar medium, as well as optical and LIDAR observations of high-altitude particles in Earth's atmosphere (70–100 km), which indicate that dust monomers may not necessarily be spherical. This study investigates the influence of different ellipsoidal monomer shapes on the morphology of aggregates given various distributions of monomer sizes. Populations of aggregates are grown from a single monomer using a combination of ballistic particle–cluster aggregation and ballistic cluster–cluster aggregation regimes incorporating the rotation of monomers and aggregates. The resulting structures of the aggregates are then compared via the compactness factor, geometric cross-section and friction time. (paper)

Preparation and Characterization of UV-Curable Cyclohexanone-Formaldehyde Resin and Its Cured Film Properties

Directory of Open Access Journals (Sweden)

Guang Yang

2014-01-01

Full Text Available UV-curable cyclohexanone-formaldehyde (UVCF resin was prepared with cyclohexanone-formaldehyde (CF resin, isophorone diisocyanate (IPDI, and pentaerythritol triacrylate (PETA as base substance, bridging agent, and functional monomer, respectively. The structure of UVCF was characterized by Fourier transform infrared spectroscopy (FT-IR, 1H-nuclear magnetic resonance spectroscopy (1H-NMR, and gel permeation chromatography (GPC. The viscosity and photopolymerization behavior of the UV-curable formulations were studied. The thermal stability and mechanical properties of the cured films were also investigated. The results showed that UVCF resin was successfully prepared, the number of average molecular weight was about 2010, and its molecular weight distribution index was 2.8. With the increase of UVCF resin content, the viscosity of the UV-curable formulations increased. After exposure to UV irradiation for 230 s, the photopolymerization conversion of the UV-curable formulations was above 80%. Moreover, when the UVCF content was 60%, the formulations had high photopolymerization rate, and the cured UVCF films showed good thermal stability and mechanical properties.

Process for producing a grafted thermoplastic resin having a multiple constituent

Energy Technology Data Exchange (ETDEWEB)

Watanabe, T; Nomura, T; Higasa, A; Ito, I

1964-05-15

A process for producing a thermoplastic graft copolymer having a multiple constituent is provided to obtain a stable, weather-proof resin with high impact strength by irradiating with high energy radiations an aqueous solution composed of: (1) a polymer or copolymer of isobutylene or a mixture thereof, (2) at least one aromatic vinyl monomer, (3) at least one acrylic monomer having no carboxylic radicals, and (4) at least one unsaturated carboxylic acid. The preferable proportions of the abovesaid materials are: (1) 10% to 40%, (2) 25% to 65%, (3) 10% to 45% and (4) 3% to 20%. The resin is suitable for high impact resistant materials for use in vehicles business machines, electric appliances, housing, pipes and the like. The concentration of monomers or polymers in the total emulsified solution may generally be 10% to 80%, but 30% to 60% is preferable. The concentration of the emulsifying agent may be 0.1% to 10%, preferably 1% to 5%. The range of the radiation doses is 1 x 10/sup 4/ to 5 x 10/sup 7/ rad. A dose rate of 1 x 10/sup 3/ to 1 x 10/sup 8/ rad/hr is preferred. The irradiation temperature may be 0/sup 0/ to about 100/sup 0/C, preferably room temperature to 80/sup 0/C. The irradiation time is several minutes to some ten minutes. In one of the examples, a graft copolymer thus produced had the following composition: 27% of isobutylene, 54% of styrene, 13% of acrylonitrile and 6% of maleic acid; and it showed a tensile strength of 293 kg/cm/sup 2/, a hardness of 93R and an impact strength of 0.572 kg.m/cm/sup 2/.

Comparison of water sorption and solubility of Acropars and Meliodent heat cure acrylic resins

Directory of Open Access Journals (Sweden)

Golbidi F

2006-06-01

Full Text Available Background and Aim: Water sorption and solubility are important properties of acrylic resins. Denture base acrylic resins have low solubility. This solubility results from the leaching out of unreacted monomer and water soluble additives into the oral fluids. The solubility of denture bases can cause oral soft tissue reactions. In addition, water absorbed into this material acts as a plasticizer and decreases the mechanical properties such as hardness, transverse strength, fatigue limit and also can change the color and dimensional stability. The aim of this study was to compare the water sorption and solubility of Acropars and Meliodent heat cure acrylic resins. Materials and Methods: This experimental study was performed on the basis of ADA specification No.12 and ISO No.1567 and standards NO: 2571 of Institute of Standards & Industrial Research of Iran. Six disc form samples of each acrylic resin were prepared, with the dimension of 50×0.5 mm. After desiccating, the samples were kept in an oven for 24 hours and weighed. Then they were immersed in water, kept in oven for 7 days and weighed again. After this phase, the samples were carried to a dessicator, for 24 hours and kept in an oven for drying and were weighed for the third time. Data were analyzed with Mann Whitney and one sample t-test. P<0.05 was considered as the limit of significance. Results: Water sorption mean values were 30.5±0.1 µg/mm3 or 0.76±0.01 mg/cm2 for Meliodent samples and 30.7±0.87 µg/mm3 or 0.77±0.009 mg/cm2 for Acropars samples. No significant difference was observed in water sorption of these two materials (P=0.9. Meliodent acrylic resin showed lower solubility (1.7±0.097 µg/mm3 or 0.042±0.001 mg/cm2 than Acropars acrylic resin (2.5±0.13 µg/mm3 or 0.062±0.001 mg/cm2 (P=0.002. Conclusion: Acropars heat cure acrylic resin matched well with the requirements of the international standards for water sorption, but its solubility was not favorable. This problem

An investigation on the effects of different polymerization techniques on dimensional changes ofAcropars, an Iranian autopolymerizing acrylic resin

Directory of Open Access Journals (Sweden)

Ebadian B

2004-02-01

Full Text Available Iranian product, Acropars autopolymerizing acrylic resin is nowadays widely used in"ndental prostheses. Dimensional change is a common problem among Iranian made acrylic resins in making"ncustom trays and record bases, seems to be more than the similar foreign products. In order to achieve a"ntechnique for making a record base with minimum dimensional changes, more research is necessary."nPurpose: The aim of the present study was to determine a curing technique for Iranian autopolymerizing"nacrylic resins leading to the least polymerization shrinkage and the most adaptation between record bases and"nstone casts."nMaterials and Methods: In this experimental study, 40 stone casts were divided into four 10- member group."nFor each group, polymerization shrinkage was determined at three points with one of the following"ntechniques: Bench curing, Curing under a coat of petroleum jelly , Curing in a monomer saturated"natmosphere, Curing in boiled water. Adaptation between bases and stone casts were measured at three points"n(the right and left crests of the ridge and the midpalatal region with a light-measuring microscope. To analyze"nthe data, Variance analysis was used."nResults: The monomer atmosphere technique showed the minimum dimensional changes and the samples in"nboiled water group had the maximum dimensional changes. No statistical differences were observed between"nother groups."nConclusion: More adaptation between record bases and stone casts was observed in monomer atmosphere"npolymerization technique. The differences between bench curing and curing under a coat of petroleum jelly"ntechniques with this method were not statistically significant. Therefore, it is suggested for making base"nrecords with maximum adaptation.

Scattering Studies of Hydrophobic Monomers in Liposomal Bilayers: An Expanding Shell Model of Monomer Distribution

International Nuclear Information System (INIS)

Richter, Andrew; Dergunov, Sergey; Ganus, Bill; Thomas, Zachary; Pingali, Sai Venkatesh; Urban, Volker S.; Liu, Yun; Porcar, Lionel; Pinkhassik, Eugene

2011-01-01

Hydrophobic monomers partially phase separate from saturated lipids when loaded into lipid bilayers in amounts exceeding a 1:1 monomer/lipid molar ratio. This conclusion is based on the agreement between two independent methods of examining the structure of monomer-loaded bilayers. Complete phase separation of monomers from lipids would result in an increase in bilayer thickness and a slight increase in the diameter of liposomes. A homogeneous distribution of monomers within the bilayer would not change the bilayer thickness and would lead to an increase in the liposome diameter. The increase in bilayer thickness, measured by the combination of small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), was approximately half of what was predicted for complete phase separation. The increase in liposome diameter, measured by dynamic light scattering (DLS), was intermediate between values predicted for a homogeneous distribution and complete phase separation. Combined SANS, SAXS, and DLS data suggest that at a 1.2 monomer/lipid ratio approximately half of the monomers are located in an interstitial layer sandwiched between lipid sheets. These results expand our understanding of using self-assembled bilayers as scaffolds for the directed covalent assembly of organic nanomaterials. In particular, the partial phase separation of monomers from lipids corroborates the successful creation of nanothin polymer materials with uniform imprinted nanopores. Pore-forming templates do not need to span the lipid bilayer to create a pore in the bilayer-templated films.

Synthesis of Novel Polymeric Resins by Gamma Irradiation for Separation of In(III) ions from Cd(II) in Aqueous Media

International Nuclear Information System (INIS)

Massoud, A.; Abou El-Nour, F.; Killa, H.

2012-01-01

In this work, Zn(II)polymethacrylates and poly(acrylamide-acrylic acid) were prepared by gamma irradiation polymerization technique of the corresponding monomer at 30 kGy. The polymeric resins were mixed with Indium ions to determine its capacity in aqueous solutions using batch experiment. The adsorption efficiency of obtained polymeric resins toward In(III) and Cd(II) in different experimental conditions was established. Batch and column methods were applied for separation of indium and cadmium. The effects of various eluants such as H 2 SO 4 , NH 4 NO 3 , HNO 3 and HCl on the recovery of both metal ions were studied. The polymeric resins may be regenerated using 3M HCl solutions.

Monoclonal antibody fragment removal mediated by mixed mode resins.

Science.gov (United States)

O'Connor, Ellen; Aspelund, Matthew; Bartnik, Frank; Berge, Mark; Coughlin, Kelly; Kambarami, Mutsa; Spencer, David; Yan, Huiming; Wang, William

2017-05-26

Efforts to increase monoclonal antibody expression in cell culture can result in the presence of fragmented species requiring removal in downstream processing. Capto adhere, HEA Hypercel, and PPA Hypercel anion exchange/hydrophobic interaction mixed mode resins were evaluated for their fragment removal capabilities and found to separate large hinge IgG1 antibody fragment (LHF) from monomer. Removal of greater than 75% of LHF population occurred at pH 8 and low conductivity. The mechanism of fragment removal was investigated in two series of experiments. The first experimental series consisted of comparison to chromatographic behavior on corresponding single mode resins. Both single mode anion exchange and hydrophobic interaction resins failed to separate LHF. The second experimental series studied the impact of phase modifiers, ethylene glycol, urea, and arginine on the mixed mode mediated removal. The addition of ethylene glycol decreased LHF removal by half. Further decreases in LHF separation were seen upon incubation with urea and arginine. Therefore, it was discovered that the purification is the result of a mixed mode phenomena dominated by hydrophobic interaction and hydrogen bonding effects. The site of interaction between the LHF and mixed mode resin was determined by chemical labeling of lysine residues with sulfo-NHS acetate. The labeling identified the antibody hinge and light chain regions as mediating the fragment separation. Sequence analysis showed that under separation conditions, a hydrophobic proline patch and hydrogen bonding serine and threonine residues mediate the hinge interaction with the Capto adhere ligand. Additionally, a case study is presented detailing the optimization of fragment removal using Capto adhere resin to achieve purity and yield targets in a manufacturing facility. This study demonstrated that mixed mode resins can be readily integrated into commercial antibody platform processes when additional chromatographic abilities

Method for coating a resinous coating material. [electron beam irradiation

Energy Technology Data Exchange (ETDEWEB)

Ino, T; Fujioka, S; Mibae, J; Takahashi, M

1968-07-13

The strength, flexibility and durability of a vinyl chloride resin, acryl resin and the like are improved. This method of application comprises the steps of applying and thereafter radically curing a mixture composed of a polymer (II) having double bond(s) on its side chain and an ethylenic unsaturated monomer, said polymer (II) being obtained by the reaction between an unsaturated carboxylic acid or anhydride represented by the formula XCH = CHY (X = (CH/sub 2/)sub(n)COOH, where 0 <= n <= 2, Y = COOR/sub 1/ or R/sub 2/(R/sub 1/ and R/sub 2/ are hydrogen or an alkyl group having from 1 to 10 atoms of carbon)) and the acrylic copolymer (I), containing a hydroxyl group, obtained by copolymerization of 10 to 50% by weight of at least one selected from the group of beta-hydroxy alkyl acrylate, beta-hydroxy alkyl methacrylate, N-methylol acrylamide and N-methylol methacryl amide with at least one selected from the group of acrylic ester, methacrylic ester and stylene. The copolymer (I) can be obtained by the usual radical polymerization such as bulk polymerization, solution polymerization, suspension polymerization or the like. The polymer (II) is dissolved in the ethylenic unsaturated monomer and radically cured with radical polymerization catalysts or electron beams, etc. The energy range of the electron beams may be 0.1 to 3 MeV. Any type of electron accelerator may be used.

Effects of trimethylsilane plasma coating on the hydrophobicity of denture base resin and adhesion of Candida albicans on resin surfaces.

Science.gov (United States)

Liu, Tianshuang; Xu, Changqi; Hong, Liang; Garcia-Godoy, Franklin; Hottel, Timothy; Babu, Jegdish; Yu, Qingsong

2017-12-01

Candida-associated denture stomatitis is the most common oral mucosal lesion among denture wearers. Trimethylsilane (TMS) plasma coating may inhibit the growth of Candida albicans on denture surfaces. The purpose of this in vitro study was to investigate whether TMS plasma coatings can effectively reduce C albicans adhesion on denture base acrylic resin surfaces. Sixty denture base acrylic resin disks with smooth and rough surfaces were prepared and were either left untreated (control group) or coated with TMS monomer (experimental group) by using plasma. Contact angles were measured immediately after TMS plasma coating. The morphology of C albicans adhesion was observed with scanning electron microscopy (SEM). Energy-dispersive spectroscopy (EDS) was used to characterize the elemental composition of the specimen surface. An adhesion test was performed by incubating the resin disk specimens in C albicans suspensions (1×10 7 cells/mL) at 37°C for 24 hours and further measuring the optical density of the C albicans by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay test. One-way ANOVA and 2-way ANOVA were followed by a post hoc test analysis (α=.05). The group with TMS coating exhibited a more hydrophobic surface than the control group. EDS analysis revealed successful TMS plasma coating. The difference in the mean contact angles between the uncoated group and the TMS-coated group was statistically significant (Pcoating than on the surfaces of the experimental group. In the adhesion test, the amount of C albicans adhering to the surface of denture base resin with the TMS coating was significantly less than that on the surfaces without TMS coating (Pcoating significantly reduced the adhesion of C albicans to the denture base resin and may reduce denture stomatitis. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

Experimental and numerical investigations of shock and shear wave propagation induced by femtosecond laser irradiation in epoxy resins

International Nuclear Information System (INIS)

Ecault, Romain; Touchard, Fabienne; Boustie, Michel; Berthe, Laurent; Lescoute, Emilien; Sollier, Arnaud; Voillaume, Hubert

2015-01-01

In this work, original shock experiments are presented. Laser-induced shock and shear wave propagations have been observed in an epoxy resin, in the case of femtosecond laser irradiation. A specific time-resolved shadowgraphy setup has been developed using the photoelasticimetry principle to enhance the shear wave observation. Shear waves have been observed in epoxy resin after laser irradiation. Their propagation has been quantified in comparison with the main shock propagation. A discussion, hinging on numerical results, is finally given to improve understanding of the phenomenon. (paper)

Reactivity of vinyl ethers and vinyl ribosides in UV-initiated free radical copolymerization with acceptor monomers.

Science.gov (United States)

Pichavant, Loic; Guillermain, Céline; Coqueret, Xavier

2010-09-13

The reactivity of various vinyl ethers and vinyloxy derivatives of ribose in the presence of diethyl fumarate or diethyl maleate was investigated for evaluating the potential of donor-acceptor-type copolymerization applied to unsaturated monomers derived from renewable feedstock. The photochemically induced polymerization of model monomer blends in the bulk state was monitored by infrared spectroscopy. The method allowed us to examine the influence of monomer pair structure on the kinetic profiles. The simultaneous consumption of both monomers was observed, supporting an alternating copolymerization mechanism. A lower reactivity of the blends containing maleates compared with fumarates was confirmed. The obtained kinetic data revealed a general correlation between the initial polymerization rate and the Hansen parameter δ(H) associated with the H-bonding aptitude of the donor monomer.

A Study of the Curing and Flammability Properties of Bisphenol A Epoxy Diacrylate Resin Utilizing a Novel Flame Retardant Monomer, bis[di-acryloyloxyethyl]-p-tert-butyl-phenyl Phosphate

Directory of Open Access Journals (Sweden)

Syang-Peng Rwei

2017-02-01

Full Text Available A UV-curable, flame-retardant monomer, DAPP (bis[di-acryloyloxyethyl]-p-tert-butyl-phenyl-phosphate, was synthesized based on BPDCP (4-tert-butylphenyl-dichloro phosphate and HEA (2-hydroxy ethyl acrylate. DAPP was blended with regular bisphenol A epoxy acrylate (BAEA in various ratios to yield various phosphorus contents. The TGA-IR (thermogravimetric analyzer interface with an infrared spectrometer results demonstrate that compounding 30 mol % DAPP with BAEA significantly reduced the amount of released CO gas. In contrast, the peak intensity of CO2 is independent of phosphorus content. The limiting oxygen index (LOI, reaching the saturated value of 26, and the heat release rate (HRR measured using a cone-calorimeter, 156.43 KW/m2, confirm the saturation point when 30 mol % DAPP was compounded into BAEA. A study of the kinetics of pyrolysis reveals that Ea decreases as the phosphorus content increases. Both the TGA-IR and pyrolysis results reveal that the phosphorus compound DAPP is easily decomposed during the initial stage of burning to form an insulating layer, which inhibits further burning of the resin and the consequent release of other flammable gases.

Synthesis of the diazonium (perfluoroalkyl) benzenesulfonimide monomer from Nafion monomer for proton exchange membrane fuel cells

Science.gov (United States)

Mei, Hua; D'Andrea, Dan; Nguyen, Tuyet-Trinh; Nworie, Chima

2014-02-01

One diazonium (perfluoroalkyl) benzenesulfonimide monomer, perfluoro-3, 6-dioxa-4-methyl-7-octene benzenesulfonyl imide, has been synthesized from Nafion monomer for the first time. With trifluorovinyl ether and diazonium precursors, the partially-fluorinated diazonium PFSI monomer can be polymerized and will provide chemically bonding with carbon electrode in proton exchange membrane fuel cells. A systematic study of the synthesis and characterization of this diazonium PFSI monomer has been conducted by varying reaction conditions. The optimized synthesis method has been established in the lab.

Production of sorption-active polypropylene fibers by radiation-induced grafting of glycidyl methacrylate as a precursor monomer

International Nuclear Information System (INIS)

Bondar, Yu.V.; Kim, H.J.; Lim, Y.J.

2006-01-01

The design and development of sorption-active natural and synthetic polymer fibers and textile materials is of great scientific and practical interest. The advantages of that type of polymeric adsorbents, as their highly developed specific surface, excellent ion-exchange and adsorption parameters and ease of their use especially under continuous conditions, allow them to find a great application in the chemical, biomedical, ecological and industrial fields. To obtain functional polymer materials with the desired performance, the non-active polymer surface have to be modified. Among different innovative techniques used for the introduction of graft chains, the radiation-chemical method of initiation has some economical and ecological preferences over others. It allows to introduce into inert polymeric matrix chains of a monomer already containing a desirable functional group, or to graft chains of a precursor-monomer and subsequently its chemical modification to form required functional groups. At present an epoxy-group containing monomer, glycidyl methacrylate (GMA), is successfully used as a precursor-monomer for production of polymeric adsorbents of variety applications on the base of membranes, films, fibers and fabrics. Two types of sorption-active polypropylene fiber carrying strong-acid sulfonate groups and amino groups have been synthesized by radiation-induced graft polymerization of GMA, with subsequent chemical modification of the epoxy groups of poly-GMA graft chains. The effect of various polymerization parameters on the GMA grafting degree was investigated in detail. The epoxy ring-opening of poly-GMA graft chains with introduction of strong-acid sulfonate groups was carried out with sodium hydrogen sulfite in water-dimethylformamide solution at 70 deg C. The main peculiarities of the sulfonation reaction in depending on the reaction time and GMA grafting degree have been investigated. Amine groups were incorporated by treatment of the GMA

Increased resin flow in mature pine trees growing under elevated CO2 and moderate soil fertility

Science.gov (United States)

K.A. Novick; G.G. Katul; H.R. McCarthy; R. Oren

2012-01-01

Warmer climates induced by elevated atmospheric CO2 (eCO2) are expected to increase damaging bark beetle activity in pine forests, yet the effect of eCO2 on resin production—the tree’s primary defense against beetle attack—remains largely unknown. Following growth-differentiation balance theory, if extra carbohydrates produced under eCO2 are not consumed by respiration...

Conformationally locked aryl C-nucleosides: synthesis of phosphoramidite monomers and incorporation into single-stranded DNA and LNA (locked nucleic acid)

DEFF Research Database (Denmark)

Babu, B. Ravindra; Prasad, Ashok K.; Trikha, Smriti

2002-01-01

. The phosphoramidite approach was used for automated incorporation of the LNA-type beta-configured C-aryl monomers 17a-17e into short DNA and 2'-OMe-RNA/LNA strands. It is shown that universal hybridization can be obtained with a conformationally restricted monomer as demonstrated most convincingly for the pyrene LNA...... monomer 17d, both in a DNA context and in an RNA-like context. Increased binding affinity of oligonucleotide probes for universal hybridization can be induced by combining the pyrene LNA monomer 17d with affinity-enhancing 2'-OMe-RNA/LNA monomers....

Luminal and parenteral TFF2 and TFF3 dimer and monomer in two models of experimental colitis in the rat

DEFF Research Database (Denmark)

Poulsen, Steen Seier; Kissow, Hannelouise; Hare, Kristine

2005-01-01

% dextran sodium sulphate in the drinking water or by one intraperitoneal injection of mitomycin C, 3.75 mg/kg. TFF peptides were administered as subcutaneous injections or directly into the lumen via a catheter placed in the proximal colon. Treatments were saline, TFF2, TFF3 monomer or TFF3 dimer 5 mg......2 had positive effect only in DSS-induced colitis. The TFF3 monomer was without any effects in both models. Treatment effect was most pronounced in the middle part of the colon, closest to the tip of the catheter. Injected TFF peptides, especially the TFF3 monomer, aggravated the colitis score...... in both colitis models. CONCLUSIONS: Intracolonic administration of TFF3 dimer and TFF2 improves experimentally induced colitis in rats. The TFF3 monomer has no effect. Parenteral administration of TFF peptides aggravates the colitis especially the TFF3 monomer....

Synthesis and characterization of UV-absorbing fluorine-silicone acrylic resin polymer

Science.gov (United States)

Lei, Huibin; He, Deliang; Guo, Yanni; Tang, Yining; Huang, Houqiang

2018-06-01

A series of UV-absorbing fluorine-silicone acrylic resin polymers containing different amount of UV-absorbent were successfully prepared by solution polymerization, with 2-[3-(2H-Benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate (BHEM), vinyltrimethoxysilane (VTMS) and hexafluorobutyl methacrylate (HFMA) as modifying monomers. The acrylic polymers and the coatings thereof were characterized by Fourier transform infrared spectrum (FT-IR), X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-vis) absorption spectrum, thermogravimetric analysis (TGA), water contact angle (CA) and Xenon lamp artificial accelerated aging tests. Results indicated that the resin exhibited high UV absorption performance as well as good thermal stability. The hydrophobicity of the coatings was of great improvement because of the bonded fluorine and silicone. Meanwhile, the weather-resistance was promoted through preferably colligating the protective effects of BHEM, organic fluorine and silicone. Also, a fitting formula about the weatherability with the BMHE content was tentatively proposed.

Curing behavior and reaction kinetics of binder resins for 3D-printing investigated by dielectric analysis (DEA)

Science.gov (United States)

Möginger, B.; Kehret, L.; Hausnerova, B.; Steinhaus, J.

2016-05-01

3D-Printing is an efficient method in the field of additive manufacturing. In order to optimize the properties of manufactured parts it is essential to adapt the curing behavior of the resin systems with respect to the requirements. Thus, effects of resin composition, e.g. due to different additives such as thickener and curing agents, on the curing behavior have to be known. As the resin transfers from a liquid to a solid glass the time dependent ion viscosity was measured using DEA with flat IDEX sensors. This allows for a sensitive measurement of resin changes as the ion viscosity changes two to four decades. The investigated resin systems are based on the monomers styrene and HEMA. To account for the effects of copolymerization in the calculation of the reaction kinetics it was assumed that the reaction can be considered as a homo-polymerization having a reaction order n≠1. Then the measured ion viscosity curves are fitted with the solution of the reactions kinetics - the time dependent degree of conversion (DC-function) - for times exceeding the initiation phase representing the primary curing. The measured ion viscosity curves can nicely be fitted with the DC-function and the determined fit parameters distinguish distinctly between the investigated resin compositions.

Paramagnetic epoxy resin

Directory of Open Access Journals (Sweden)

E. C. Vazquez Barreiro

2017-01-01

Full Text Available This work illustrates that macrocycles can be used as crosslinking agents for curing epoxy resins, provided that they have appropriate organic functionalities. As macrocycles can complex metal ions in their structure, this curing reaction allows for the introduction of that metal ion into the resin network. As a result, some characteristic physical properties of the metallomacrocycle could be transferred to the new material. The bisphenol A diglycidyl ether (BADGE, n = 0 and hemin (a protoporphyrin IX containing the Fe(III ion, and an additional chloride ligand have been chosen. The new material has been characterized by differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, Fourier Transform Infrared (FT-IR, Nuclear Magnetic Resonance (NMR, Transmission Electron Microscopy (TEM, and magnetic susceptibility measurements. Fe(III remains in the high-spin state during the curing process and, consequently, the final material exhibits the magnetic characteristics of hemin. The loss of the chlorine atom ligand during the cure of the resin allows that Fe(III can act as Lewis acid, catalyzing the crosslinking reactions. At high BADGE n = 0/hemin ratios, the formation of ether and ester bonds occurs simultaneously during the process.

Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran

Directory of Open Access Journals (Sweden)

Sari Fouad

2012-12-01

Full Text Available We reported in this work that the cationic copolymerization in one step takes place between carbon–carbon double-bond monomer styrene with cyclic monomer tetrahydrofuran. The comonomers studied belong to different families: vinylic and cyclic ether. The reaction is initiated with maghnite-H+ an acid exchanged montmorillonite as acid solid ecocatalyst. Maghnite-H+ is already used as catalyst for polymerization of many vinylic and heterocyclic monomers. The oxonium ion of tetrahydrofuran and carbonium ion of styrene propagated the reaction of copolymerization. The acetic anhydride is essential for the maintenance of the ring opening of tetrahydrofuran and the entry in copolymerization. The temperature was kept constant at 40°C in oil bath heating for 6 hours. A typical reaction product was analyzed by 1H-NMR, 13C-NMR and IR and the formation of the copolymer was confirmed. The reaction was proved by matched with analysis. The maghnite-H+ allowed us to obtain extremely pure copolymer in good yield by following a simples operational conditions. Copyright © 2012 by BCREC UNDIP. All rights reservedReceived: 29th October 2012; Revised: 29th November 2012; Accepted: 29th November 2012[How to Cite: S. Fouad, M.I. Ferrahi, M. Belbachir. (2012. Copolymerization of Carbon–carbon Double-bond Monomer (Styrene with Cyclic Monomer (Tetrahydrofuran. Bulletin of Chemical Reaction Engineering & Catalysis, 7(2: 165-171. (doi:10.9767/bcrec.7.2.4074.165-171][How to Link / DOI: http://dx.doi.org/10.9767/bcrec.7.2.4074.165-171 ] | View in 

Development of new and improved polymer matrix resin systems, phase 1

Science.gov (United States)

Hsu, M. S.

1983-01-01

Vinystilbazole (vinylstryrylpyridine) and vinylpolystyrulpyridine were prepared for the purpose of modifying bismaleimide composite resins. Cure studies of resins systems were investigated by differential scanning calorimetry. The vinylstyrylpyridine-modified bismaleimide composite resins were found to have lower cure and gel temperatures, and shorter cure times than the corresponding unmodified composite resins. The resin systems were reinforced with commercially avialable satin-weave carbon cloth. Prepregs were fabricated by solvent or hot melt techniques. Thermal stability, flammability, moisture absorption, and mechanical properties of the composites (such as flexural strength, modulus, tensile and short beam shear strength) were determined. Composite laminates showed substantial improvements in both processability and mechanical properties compared to he bismaleimide control systems. The vinylstyrylpyridine modified bismaleimide resins can be used as advanced matrix resins for graphite secondary structures where ease of processing, fireworthiness, and high temperature stability are required for aerospace applications.

Graft copolymers of polyurethane with various vinyl monomers via radiation-induced miniemulsion polymerization: Influential factors to grafting efficiency and particle morphology

Energy Technology Data Exchange (ETDEWEB)

Wang Hua [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China); Wang Mozhen [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)], E-mail: pstwmz@ustc.edu.cn; Ge Xuewu [CAS Key Laboratory of Soft Matter Chemistry, Department of Polymer Science and Engineering, University of Science and Technology of China (USTC), Hefei, Anhui 230026 (China)], E-mail: xwge@ustc.edu.cn

2009-02-15

Graft copolymers of polyurethane (PU) with various vinyl monomers were synthesized through a one-pot but two-step miniemulsion polymerization process. Firstly, the polycondensation of isophorone diisocyanate (IPDI) with hydroxyl-terminated polybutadiene (HTPB) had been performed in aqueous miniemulsion at 40 deg. C in order to obtain PU dispersions. Consecutively, an in-situ graft copolymerization of the vinyl monomers with the synthesized PU was initiated by {gamma}-ray radiation at room temperature. The grafting efficiency of PU with vinyl monomer (G{sub PU/monomer}) was calculated from {sup 1}H NMR spectra and the particle morphology of the final hybrid latex was observed by transmission electron microscopy (TEM). As there was no monomer transferring in miniemulsion system, homogenous hybrid particles would be synthesized provided that the monomer was miscible with PU, such as styrene. With the increase of the polarity of the monomer, the compatibility of PU with monomer decreased. G{sub PU/monomer} varied as G{sub PU/styrene}(37%)>G{sub PU/butyl} {sub acrylate} {sub (BA)}(21%)>G{sub PU/methyl} {sub methacrylate} {sub (MMA)}(12%). The proportion of homogeneous nucleation would increase as the hydrophilicity of the monomer increased. High temperature would destabilize the miniemulsion so as to result in a less grafting efficiency. Compared to the phase separation during the seeded emulsion polymerization, the miniemulsion polymerization method facilitated the preparation of homogeneous materials owing to its monomer droplet nucleation mechanism.

Method for removing cesium from aqueous liquid, method for purifying the reactor coolant in boiling water and pressurized water reactors and a mixed ion exchanged resin bed, useful in said purification

International Nuclear Information System (INIS)

Otte, J.N.A.; Liebmann, D.

1989-01-01

The invention relates to a method for removing cesium from an aqueous liquid, and to a resin bed containing a mixture of an anion exchange resin and cation exchange resin useful in said purification. In a preferred embodiment, the present invention is a method for purifying the reactor coolant of a presurized water or boiling water reactor. Said method, which is particularly advantageously employed in purifying the reactor coolant in the primary circuit of a pressurized reactor, comprises contacting at least a portion of the reactor coolant with a strong base anion exchange resin and the strong acid cation exchange resin derived from a highly cross-linked, macroporous copolymer of a monovinylidene aromatic and a cross-linking monomer copolymerizable therewith. Although the reactor coolant can sequentially be contacted with one resin type and thereafter with the second resin type, the contact is preferably conducted using a resin bed comprising a mixture of the cation and anion exchange resins. 1 fig., refs

Graft copolymers of polypropylene films. 1. radiation induced grafting of mixed monomers. Vol. 3

International Nuclear Information System (INIS)

El-Salmawi, K.M.; El-Naggar, A.M.; Said, H.M.; Zahran, A.H.

1996-01-01

Radiation graft copolymerization of co monomer mixtures of acrylic acid (AAC), and styrene (S) onto polypropylene (PP) film by mutual method has been investigated. The effects of different factors that may affect the grafting yield such as inhibitor concentration (Mohr's salt), solvent composition (MeOH and H 2 O), radiation dose and dose rate were considered. It was found that the role of Mohr's salt is very effective when the ratio of AAC in the co monomer mixtures was at lower values. However, the addition of 1.25 Wt% of Mohr's salt reduced the homo polymer formation and enhances the grafting process. Graft copolymerization in presence of solvent mixture composed of methanol and water was found to afford higher grafting than in pure methanol regardless of the composition of the co monomer mixture used. However, the highest degree of grafting was obtained at a solvent composition of 20% H 2 O:80%MeOH and a co monomer mixture of 20%AAC:80%sty. An attempt was made to determine each PAAC and PS fractions in the total graft yield obtained. Two methods of analysis based on using the reactivity ratios reported in literature, elemental analysis and IR spectroscopy. The determination of poly (acrylic acid) and polystyrene fractions by elemental analysis is believed more accurate than these by reactivity ratio. The precise results obtained by elemental analysis with respect to the chemical structure of known polymer prepared under identical conditions. The results obtained by IR measurements go well with that obtained with the reactivity ratio methods. 5 figs., 3 tabs

Preparation and characterization of silane-modified SiO2 particles reinforced resin composites with fluorinated acrylate polymer.

Science.gov (United States)

Liu, Xue; Wang, Zengyao; Zhao, Chengji; Bu, Wenhuan; Na, Hui

2018-04-01

A series of fluorinated dental resin composites were prepared with two kinds of SiO 2 particles. Bis-GMA (bisphenol A-glycerolate dimethacrylate)/4-TF-PQEA (fluorinated acrylate monomer)/TEGDMA (triethylene glycol dimethacrylate) (40/30/30, wt/wt/wt) was introduced as resin matrix. SiO 2 nanopartices (30nm) and SiO 2 microparticles (0.3µm) were silanized with 3-methacryloxypropyl trimethoxysilane (γ-MPS) and used as fillers. After mixing the resin matrix with 0%, 10%, 20%, 30% SiO 2 nanopartices and 0%, 10%, 20%, 30%, 40%, 50% SiO 2 microparticles, respectively, the fluorinated resin composites were obtained. Properties including double bond conversion (DC), polymerization shrinkage (PS), water sorption (W p ), water solubility (W y ), mechanical properties and cytotoxicity were investigated in comparison with those of neat resin system. The results showed that, filler particles could improve the overall performance of resin composites, particularly in improving mechanical properties and reducing PS of composites along with the addition of filler loading. Compared to resin composites containing SiO 2 microparticles, SiO 2 nanoparticles resin composites had higher DC, higher mechanical properties, lower PS and lower W p under the same filler content. Especially, 50% SiO 2 microparticles reinforced resins exhibited the best flexural strength (104.04 ± 7.40MPa), flexural modulus (5.62 ± 0.16GPa), vickers microhardness (37.34 ± 1.13 HV), compressive strength (301.54 ± 5.66MPa) and the lowest polymerization (3.42 ± 0.22%). Copyright © 2018 Elsevier Ltd. All rights reserved.

Cytotoxicity and cytokine expression induced by silorane and methacrylate-based composite resins.

Science.gov (United States)

Longo, Daniele Lucca; Paula-Silva, Francisco Wanderley Garcia; Faccioli, Lucia Helena; Gatón-Hernández, Patrícia Maria; Queiroz, Alexandra Mussolino de; Silva, Léa Assed Bezerra da

2016-01-01

The aim of this study was to evaluate cytotoxicity and cytokine production induced by light-cured or non-light-cured methacrylate-based and silorane composite resins in RAW 264.7 macrophages. Cells were stimulated with the extracts from light-cured or non-light-cured composite resins. After incubation for 24 h, cytotoxicity was assessed with the lactate dehydrogenase (LDH) and methyl thiazolyl tetrazolium (MTT) assays, and total protein was quantified using the Lowry method. TNF-α detection was examined with an enzyme-linked immunosorbent assay (ELISA) conducted with cell supernatants after cell stimulation for 6, 12, and 24 h. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's post hoc test (α=0.05). KaloreTM and FiltekTM Silorane were cytotoxic with or without light curing (p0.05). However, after 24 h FiltekTM Silorane inhibited the production of TNF-α (p<0.05). KaloreTM and FiltekTM Silorane were cytotoxic regardless of light curing. The extract obtained from KaloreTM after 15 days of incubation stimulated the production of TNF-α, unlike that obtained from FiltekTM Silorane.

Thermodynamics of monomer partitioning in polymer latices: effect of molar volume of the monomers

NARCIS (Netherlands)

Schoonbrood, H.A.S.; German, A.L.

1994-01-01

A model of the thermodn. of partitioning of moderately water-sol. monomers in polymer latex systems is developed to show deviations that occur when the molar vols. of the monomers are not similar. The model, as well as expts. with Me acrylate and cyclohexyl methacrylate in polystyrene latex systems,

Net expansion of dried demineralized dentin matrix produced by monomer/alcohol saturation and solvent evaporation.

Science.gov (United States)

Agee, Kelli A; Becker, Thomas D; Joyce, Anthony P; Rueggeberg, Frederick A; Borke, James L; Waller, Jennifer L; Tay, Franklin R; Pashley, David H

2006-11-01

The purpose of this work was to determine if nonaqueous methacrylate monomer/alcohol mixtures could expand dried collapsed demineralized dentin matrix. Thin disks (ca. 200 microm) of human dentin were demineralized and placed in wells beneath contact probes of linear variable differential transformers. The probes were placed on water-saturated expanded matrices to record the shrinkage associated with drying. Monomer mixtures containing hydroxyethyl methacrylate, 2,2-bis[4-(2-hydroxy-3 methacryloyloxy)propoxyphenyl] propane, or triethyleneglycol dimethacrylate were mixed with methanol or ethanol at alcohol/monomer mass fraction % of 90/10, 70/30, 50/50, or 30/70. They were randomly applied to the dried matrices to determine the rate and magnitude of expansion; then shrinkage was recorded during evaporation of the alcohols. The results indicated that matrix expansion was positively correlated with the Hoy's solubility parameters for hydrogen bonding forces (delta(h)) of the monomer/solvent mixtures (p methanol-containing than with ethanol-containing monomer mixtures. For the test solutions, triethyleneglycol dimethacrylate-containing mixtures produced the slowest rate of matrix expansion and hydroxyethyl methacrylate-containing mixtures the most rapid expansion. When the solvents were evaporated, the matrix shrank in proportion to the solvent content and the delta(h) of the monomer-solvent mixtures. The results indicate that expansion of dried, collapsed dentin matrices requires that the delta(h) of the mixtures be larger than 17 (J/cm(3))(1/2). The greater the delta(h) of the monomer solutions, the greater the rate and extent of expansion.

The mutual diffusion coefficient for (meth)acrylate monomers as determined with a nuclear microprobe

International Nuclear Information System (INIS)

Leewis, Christian M.; Mutsaers, Peter H.A.; Jong, Arthur M. de; Ijzendoorn, Leo J. van; Voigt, Martien J.A. de; Ren, Min Q.; Watt, Frank; Broer, Dirk J.

2004-01-01

The value of the mutual diffusion coefficient D V of two acrylic monomers is determined with nuclear microprobe measurements on a set of polymer films. These films have been prepared by allowing the monomers to diffuse into each other for a certain time and subsequently applying fast ultraviolet photo-polymerization, which freezes the concentration profile. The monomer diffusion profiles are studied with a scanning 2.1 MeV proton microprobe. Each monomer contains a marker element, e.g., Cl and Si, which are easily detected with proton induced x-ray emission. From the diffusion profiles, it is possible to determine the mutual diffusion coefficient. The mutual diffusion coefficient is dependent of concentration, which is concluded from the asymmetry in the Cl- and Si-profiles. A linear dependence of the mutual diffusion coefficient on the composition is used as a first order approximation. The best fits are obtained for a value of b=(0.38±0.15), which is the ratio of the diffusion coefficient of 1,3-bis(3-methacryloxypropyl)-1, 1,3,3-tetramethyldisiloxane in pure 2-chloroethyl acrylate and the diffusion coefficient of 2-chloroethyl acrylate in pure 1,3-bis(3-methacryloxypropyl)-1,1,3,3-tetramethyldisiloxane. Under the assumption of a linear dependence of the mutual diffusion coefficient D V on monomer composition, it follows that D V =(2.9±0.6)·10 -10 m 2 /s at a 1:1 monomer ratio. With Flory-Huggins expressions for the monomer chemical potentials, one can derive approximate values for the individual monomer diffusion coefficients

Silver distribution and release from an antimicrobial denture base resin containing silver colloidal nanoparticles.

Science.gov (United States)

Monteiro, Douglas Roberto; Gorup, Luiz Fernando; Takamiya, Aline Satie; de Camargo, Emerson Rodrigues; Filho, Adhemar Colla Ruvolo; Barbosa, Debora Barros

2012-01-01

The aim of this study was to evaluate a denture base resin containing silver colloidal nanoparticles through morphological analysis to check the distribution and dispersion of these particles in the polymer and by testing the silver release in deionized water at different time periods. A Lucitone 550 denture resin was used, and silver nanoparticles were synthesized by reduction of silver nitrate with sodium citrate. The acrylic resin was prepared in accordance with the manufacturers' instructions, and silver nanoparticle suspension was added to the acrylic resin monomer in different concentrations (0.05, 0.5, and 5 vol% silver colloidal). Controls devoid of silver nanoparticles were included. The specimens were stored in deionized water at 37°C for 7, 15, 30, 60, and 120 days, and each solution was analyzed using atomic absorption spectroscopy. Silver was not detected in deionized water regardless of the silver nanoparticles added to the resin and of the storage period. Micrographs showed that with lower concentrations, the distribution of silver nanoparticles was reduced, whereas their dispersion was improved in the polymer. Moreover, after 120 days of storage, nanoparticles were mainly located on the surface of the nanocomposite specimens. Incorporation of silver nanoparticles in the acrylic resin was evidenced. Moreover, silver was not detected by the detection limit of the atomic absorption spectrophotometer used in this study, even after 120 days of storage in deionized water. Silver nanoparticles are incorporated in the PMMA denture resin to attain an effective antimicrobial material to help control common infections involving oral mucosal tissues in complete denture wearers. © 2011 by the American College of Prosthodontists.

Graft copolymers of polypropylene films. 1. radiation induced grafting of mixed monomers. Vol. 3

Energy Technology Data Exchange (ETDEWEB)

El-Salmawi, K M; El-Naggar, A M; Said, H M; Zahran, A H [Radiation Chemistry Department, National Center for Radiation Research and Technology, Atomic Energy Authority, Cairo, (Egypt)

1996-03-01

Radiation graft copolymerization of co monomer mixtures of acrylic acid (AAC), and styrene (S) onto polypropylene (PP) film by mutual method has been investigated. The effects of different factors that may affect the grafting yield such as inhibitor concentration (Mohr`s salt), solvent composition (MeOH and H{sub 2} O), radiation dose and dose rate were considered. It was found that the role of Mohr`s salt is very effective when the ratio of AAC in the co monomer mixtures was at lower values. However, the addition of 1.25 Wt% of Mohr`s salt reduced the homo polymer formation and enhances the grafting process. Graft copolymerization in presence of solvent mixture composed of methanol and water was found to afford higher grafting than in pure methanol regardless of the composition of the co monomer mixture used. However, the highest degree of grafting was obtained at a solvent composition of 20% H{sub 2} O:80%MeOH and a co monomer mixture of 20%AAC:80%sty. An attempt was made to determine each PAAC and PS fractions in the total graft yield obtained. Two methods of analysis based on using the reactivity ratios reported in literature, elemental analysis and IR spectroscopy. The determination of poly (acrylic acid) and polystyrene fractions by elemental analysis is believed more accurate than these by reactivity ratio. The precise results obtained by elemental analysis with respect to the chemical structure of known polymer prepared under identical conditions. The results obtained by IR measurements go well with that obtained with the reactivity ratio methods. 5 figs., 3 tabs.

Kinetics of Waterborne Alkyd/Acrylic Hybrid Resin Free Radical Polymerization by Two Systems of Redox and Thermal Initiators

Directory of Open Access Journals (Sweden)

shirin Madadi

2012-12-01

Full Text Available Kinetics of radical polymerizations of waterborne alkyd/acrylic hybrid resin via batch mini-emulsion technique was studied using redox initiators (TBHP/Fe2+/EDTA/AsAc  and  TBHP/Fe2+/EDTA/SFS at relatively low temperatures and thermal initiators (BPO, KPS and AIBN at higher temperatures to seek the most suitable initiator system. At the end of all reactions the unreacted monomer content was reduced using post-polymerization technique; consequently, leading to increased monomer conversion and flm formation with improved properties. The kinetics of mini-emulsion polymerization showed that in all redox initiator systems (Fe2+ catalyst + EDTA chelating agent, the radials are produced at relatively low temperature with more effcient control of the reactor temperature. It was found that at 45°C TBHP/Fe2+/EDTA/SFS redox initiator system leads to 98% monomer conversion, a much higher rate than that of systems involved thermal initiators.

Effect of mineral acid on polymer produced during radiation-induced grafting of styrene monomer

International Nuclear Information System (INIS)

Garnett, J.L.; Jankiewicz, S.V.; Sangster, D.F.

1982-01-01

The inclusion of mineral acid in a solution of styrene in methanol subjected to 60 Co γ irradiation markedly enhances the yield of monomer grafted to cellulose and other radiation grafting systems. Results were reported from a preliminary investigation into the mechanism of this acid effect through a study of the action of acid during the solution polymerization process. It was found that the presence of acid in a monomer solution such as styrene in 1, 4-dioxan led to an enhancement in the homopolymer yield of styrene; and it was showed that the acid also effected the number-average molecular weight of this homopolymer. 1 figure, 4 tables

Thermoanalytical Study and Kinetics of New 8-Hydroxyquinoline 5-sulphonic Acid-Oxamide-Formaldehyde Terpolymer Resins

Directory of Open Access Journals (Sweden)

Rajesh N. Singru

2009-01-01

Full Text Available The terpolymer resins (8-HQ5-SAOF have been synthesized by the condensation of 8-hydroxyquinoline 5-sulphonic acid (8-HQ5-SA and oxamide (O with formaldehyde (F in the presence of acid catalyst and using varied molar proportion of the reacting monomers. The synthesized terpolymer resins have been characterized by different physico-chemical techniques. Thermogravimetric analysis of all terpolymer resins in present study have been carried out by non-isothermal thermogravimetric analysis technique in which sample is subjected to condition of continuous increase in temperature at linear rate. Thermal study of the resins was carried out to determine their mode of decomposition and relative thermal stabilities. Thermal decomposition curves were studied carefully with minute details. The Freeman-Carroll and Sharp-Wentworth methods have been used in the present investigation to calculate thermal activation energy and different kinetic parameter of the terpolymer resins. Thermal activation energy (Ea calculated with above two mentioned methods are in close agreement. The advantage of Freeman-Carroll method is to calculate both the order of reaction (n and energy of activation in one single stage by keeping heating rate constant. By using data of thermogravimetric analysis, various thermodynamic parameters like frequency factor (Z, entropy change (Δ S, free energy change (Δ F and apparent entropy (S* have been determined using Freeman-Carroll method.

Oligosilylarylnitrile: The Thermoresistant Thermosetting Resin with High Comprehensive Properties.

Science.gov (United States)

Wang, Mingcun; Ning, Yi

2018-04-11

One of the highest thermoresistant thermosetting resins ever studied so far, oligosilylarylnitrile resin, was investigated first in this study. Oligosilylarylnitrile was synthesized by lithium-reduced Wurtz-Fittig condensation reaction, and the prepared viscous resin exhibited moderate rheological behaviors while heated purely or together with 20% polysilazane as a cross-linking agent. The thermal curing temperatures were found by differential scanning calorimetry at 268 °C (pure) and 158 °C (with the polysilazane cross-linking agent), which is comparably close to that of polysilylarylacetylene resin (normally at 220-250 °C) but much lower than those of polyimide and phthalonitrile resins (normally >300 °C), indicating the admirable material processability of oligosilylnitrile. The cured oligosilylarylnitrile resins have extremely high thermal resistance, indicated by the results of thermogravimetric analysis (the mass residue at 800 °C is >90% under N 2 ) and dynamic mechanical analysis (the glass-transition temperature is >420 °C). The mechanical property of the oligosilylarylnitrile-matrixed silica-cloth reinforced laminate is comparably close to those of polyimide and phthalonitrile but much higher than that of polysilylarylacetylene, indicating the enviable thermal and mechanical properties of oligosilylnitrile. Thus, among the high-temperature resins ever studied so far, the oligosilylarylnitrile resin was found to have the almost best comprehensive characteristics of processability and properties.

Monomer-dependent secondary nucleation in amyloid formation.

Science.gov (United States)

Linse, Sara

2017-08-01

Secondary nucleation of monomers on the surface of an already existing aggregate that is formed from the same kind of monomers may lead to autocatalytic amplification of a self-assembly process. Such monomer-dependent secondary nucleation occurs during the crystallization of small molecules or proteins and self-assembled materials, as well as in protein self-assembly into fibrous structures. Indications of secondary nucleation may come from analyses of kinetic experiments starting from pure monomers or monomers supplemented with a low concentration of pre-formed aggregates (seeds). More firm evidence requires additional experiments, for example those employing isotope labels to distinguish new aggregates arising from the monomer from those resulting from fragmentation of the seed. In cases of amyloid formation, secondary nucleation leads to the formation of toxic oligomers, and inhibitors of secondary nucleation may serve as starting points for therapeutic developments. Secondary nucleation displays a high degree of structural specificity and may be enhanced by mutations or screening of electrostatic repulsion.

Troglitazone induces differentiation in Trypanosoma brucei

International Nuclear Information System (INIS)

Denninger, Viola; Figarella, Katherine; Schoenfeld, Caroline; Brems, Stefanie; Busold, Christian; Lang, Florian; Hoheisel, Joerg; Duszenko, Michael

2007-01-01

Trypanosoma brucei, a protozoan parasite causing sleeping sickness, is transmitted by the tsetse fly and undergoes a complex lifecycle including several defined stages within the insect vector and its mammalian host. In the latter, differentiation from the long slender to the short stumpy form is induced by a yet unknown factor of trypanosomal origin. Here we describe that some thiazolidinediones are also able to induce differentiation. In higher eukaryotes, thiazolidinediones are involved in metabolism and differentiation processes mainly by binding to the intracellular receptor peroxisome proliferator activated receptor γ. Our studies focus on the effects of troglitazone on bloodstream form trypanosomes. Differentiation was monitored using mitochondrial markers (membrane potential, succinate dehydrogenase activity, inhibition of oxygen uptake by KCN, amount of cytochrome transcripts), morphological changes (Transmission EM and light microscopy), and transformation experiments (loss of the Variant Surface Glycoprotein coat and increase of dihydroliponamide dehydrogenase activity). To further investigate the mechanisms responsible for these changes, microarray analyses were performed, showing an upregulation of expression site associated gene 8 (ESAG8), a potential differentiation regulator

Addition of phosphotungstic acid to ethanol for dehydration improves both the ultrastructure and antigenicity of pituitary tissue embedded in LR White acrylic resin.

Science.gov (United States)

Sakai, Yuko; Hosaka, Masahiro; Hira, Yoshiki; Watanabe, Tsuyoshi

2005-12-01

Although hydrophilic acrylic resins including LR White have been widely utilized as embedding media for immunocytochemical use, the constituents of tissues are often extracted by the resin monomer during the infiltration process of the embedment, resulting in a discernible impairment of the ultrastructure when the tissue is weakly fixed only with aldehydes. To minimize the extraction by the resin monomer, the embedding procedure with LR White resin was reexamined in the present study. Among the treatments tested, a partial dehydration with 70% ethanol containing 2% phosphotungstic acid (PTA) well preserved the ultrastructure of the pituitary tissue without spoiling the antigenicity of LHbeta and other representative markers for the Golgi apparatus. In addition, treatment with 1% tannic acid (TA) prior to the dehydration described above synergistically improved both the ultrastructure and antigenicity of the tissue so that the orientation of the Golgi apparatus could be determined by double immunogold labeling with commercially available anti-GM130 and anti-TGN38 antibodies. The ultrathin sections from the LR White-embedded tissue treated with TA and dehydrated in 70% ethanol containing 2% PTA also enhanced contrast without conventional heavy-metal staining with uranyl acetate and lead citrate. Our findings further suggest that the precipitation of TA and PTA protected the tissue from being extracted during the embedment, probably because an insoluble complex was transiently formed with the constituents of the tissue. This simple modification of the LR White embedment can extend the application of post-embedding immunocytochemistry as an alternative to pre-embedding immunolabeling with frozen ultrathin sections.

One-Pot Click Access to a Cyclodextrin Dimer-Based Novel Aggregation Induced Emission Sensor and Monomer-Based Chiral Stationary Phase

Directory of Open Access Journals (Sweden)

Xiaoli Li

2016-11-01

Full Text Available A ‘two birds, one stone’ strategy was developed via a one-pot click reaction to simultaneously prepare a novel cyclodextrin (CD dimer based aggregation induced emission (AIE sensor (AIE-DCD and a monomer based chiral stationary phase (CSP-MCD for chiral high performance liquid chromatography (CHPLC. AIE-DCD was found to afford satisfactory AIE response for specific detection of Zn2+ with a detection limit of 50 nM. CSP-MCD exhibits excellent enantioseparation ability toward dansyl amino acids, where the resolution of dansyl amino leucine reaches 5.43.

Characterisation of polyhydroxyalkanoate copolymers with controllable four-monomer composition.

Science.gov (United States)

Dai, Yu; Lambert, Lynette; Yuan, Zhiguo; Keller, Jurg

2008-03-20

Polyhydroxyalkanoate (PHA) copolymers comprising the four monomers 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 3-hydroxy-2-methylvalerate (3HMV) and 3-hydroxy-2-methylbutyrate (3HMB) were generated using the recently discovered Defluviicoccus vanus-related glycogen accumulating organisms (DvGAOs) under anaerobic conditions without applying any nutrient limitations. The composition could be manipulated in a defined range by modifying the ratio of propionate and acetate provided in the feed stream. The PHAs produced were characterised as random copolymers (from propionate alone) or a mixture of random copolymers (from mixture of propionate and acetate) through microstructure analysis using 13C NMR spectroscopy. The sequence distribution of all eight comonomer pairs in the carbonyl region of 3HB and 3HV was identified and assigned with confidence utilising two-dimensional heteronuclear multiple bond coherence (HMBC) spectroscopy. Weight average molecular weights were in the range 390-560 kg/mol. Differential scanning calorimetry (DSC) traces showed that the melting temperature (Tm) varied between 70 and 161 degrees C and glass transition temperature (Tg) ranged from -8 to 0 degrees C. The incorporation of considerable amounts of 3HMV and 3HMB monomer units introduced additional "defects" into the PHBV copolymer structure and hence greatly lowered the crystallinity. The data indicate the potential of these four-monomer PHAs to be employed for practical applications, considering their favourable properties and the cost-effective production process using a mixed culture and simple carbon sources.

Evaluation of glass transition temperature and dynamic mechanical properties of autopolymerized hard direct denture reline resins.

Science.gov (United States)

Takase, Kazuma; Watanabe, Ikuya; Kurogi, Tadafumi; Murata, Hiroshi

2015-01-01

This study assessed methods for evaluation of glass transition temperature (Tg) of autopolymerized hard direct denture reline resins using dynamic mechanical analysis and differential scanning calorimetry in addition to the dynamic mechanical properties. The Tg values of 3 different reline resins were determined using a dynamic viscoelastometer and differential scanning calorimeter, and rheological parameters were also determined. Although all materials exhibited higher storage modulus and loss modulus values, and a lower loss tangent at 37˚C with a higher frequency, the frequency dependence was not large. Tg values obtained by dynamic mechanical analysis were higher than those by differential scanning calorimetry and higher frequency led to higher Tg, while more stable Tg values were also obtained by that method. These results suggest that dynamic mechanical analysis is more advantageous for characterization of autopolymerized hard direct denture reline resins than differential scanning calorimetry.

Voltage-Induced Nonlinear Conduction Properties of Epoxy Resin/Micron-Silver Particles Composites

Science.gov (United States)

Qu, Zhaoming; Lu, Pin; Yuan, Yang; Wang, Qingguo

2018-01-01

The nonlinear conduction properties of epoxy resin (ER)/micron-silver particles (MP) composites were investigated. Under sufficient high intensity applied constant voltage, the obvious nonlinear conduction properties of the samples with volume fraction 25% were found. With increments in the voltage, the conductive switching effect was observed. The nonlinear conduction mechanism of the ER/MP composites under high applied voltages could be attributed to the electrical current conducted via discrete paths of conductive particles induced by the electric field. The test results show that the ER/MP composites with nonlinear conduction properties are of great potential application in electromagnetic protection of electron devices and systems.

Reactivity of Resorcinol Formaldehyde Resin with Nitric Acid

International Nuclear Information System (INIS)

King, William D.; Fondeur, Fernando F.; Wilmarth, William R.; Pettis, Myra E.

2005-01-01

Solid-state infrared spectroscopy, differential scanning calorimetry, and elemental analysis have been used to evaluate the reactivity of resorcinol formaldehyde resin with nitric acid and characterize the solid product. Two distinct reactions were identified within the temperature range 25-55 C. The first reaction is primarily associated with resin nitration, while the second involves bulk oxidation and degradation of the polymer network leading to dissolution and off-gassing. The threshold conditions promoting reaction have been identified. Reaction was confirmed with nitric acid concentrations as low as 3 M at 25 C applied temperature and 0.625 M at 66 C. Although a nitrated resin product can be isolated under appropriate experimental conditions, calorimetry testing indicates no significant hazard associated with handling the dry material

Preparation of supramolecular polymers by copolymerization of monomers containing quadruple hydrogen bonding units with regular monomers

NARCIS (Netherlands)

2004-01-01

The invention relates to the synthesis of polymers containing self-complementary quadruple hydrogen groups by copolymerizing monomers containing a quadruple hydrogen bonding group with one or more monomers of choice. The resulting polymers show unique new characteristics due to the presence of

Dexamethasone Suppresses Oxysterol-Induced Differentiation of Monocytic Cells

Directory of Open Access Journals (Sweden)

Yonghae Son

2016-01-01

Full Text Available Oxysterol like 27-hydroxycholesterol (27OHChol has been reported to induce differentiation of monocytic cells into a mature dendritic cell phenotype. We examined whether dexamethasone (Dx affects 27OHChol-induced differentiation using THP-1 cells. Treatment of monocytic cells with Dx resulted in almost complete inhibition of transcription and surface expression of CD80, CD83, and CD88 induced by 27OHChol. Elevated surface levels of MHC class I and II molecules induced by 27OHChol were reduced to basal levels by treatment with Dx. A decreased endocytosis ability caused by 27OHChol was recovered by Dx. We also examined effects of Dx on expression of CD molecules involved in atherosclerosis. Increased levels of surface protein and transcription of CD105, CD137, and CD166 by treatment with 27OHChol were significantly inhibited by cotreatment with Dx. These results indicate that Dx inhibits 27OHChol-induced differentiation of monocytic cells into a mature dendritic cell phenotype and expression of CD molecules whose levels are associated with atherosclerosis. In addition, we examined phosphorylation of AKT induced by 27OHChol and effect of Dx, where cotreatment with Dx inhibited the phosphorylation of AKT. The current study reports that Dx regulates oxysterol-mediated dendritic cell differentiation of monocytic cells.

Fluorescent oligonucleotides containing a novel perylene 2′-amino-α-L-LNA monomer: Synthesis and analytical potential

DEFF Research Database (Denmark)

Astakhova, Irina; Kumar, Santhosh T.; Wengel, Jesper

2011-01-01

efficiency of the resulting perylene-2'-amino-alpha-L-LNA monomer (T*) into synthetic oligonucleotides was significantly improved by replacement of the typically used 1H-tetrazole activator with pyridine hydrochloride. Generally, oligonucleotides containing monomer T* showed high binding affinity towards...... incorporations of monomers T* was quenched (quantum yield Phi(F) = 0.21) relative to duplexes of this probe with complementary DNA and RNA (Phi(F) = 0.42 and 0.35, respectively). On the contrary, a strong fluorescence quenching upon target binding was demonstrated by two short oligonucleotides of analogues...... sequences containing monomers T* at 5'- and 3'-terminal positions. We explain the hybridization-induced light-up effect observed for double-labeled probe by a reduction of fluorescence quenching due to precise positioning of the fluorophores within the double-stranded complexes. Furthermore, we propose...

Radiation curing of mixture of diallylphthalate prepolymer and vinyl monomer, 11

International Nuclear Information System (INIS)

Gotoda, Masao; Yagi, Toshiaki; Yoshizawa, Iwao; Okugawa, Hideo.

1975-01-01

Preparation of Wood-Polymer Composite (WPC) piled plywood for flooring, was attempted by electron beam irradiation of American Hemlock veneer, impregnated with low molecular weight diallylphthalate prepolymer (DAPsub(p).L)/vinyl monomer mixtures, in comparison with that by thermal curing reported previously. For the improvement of the mechanical properties of WPC piled plywood, 5-15 parts of low molecular weight polyvinylacetate (PVAc) was added to DAPsub(p).L/methyl acrylate/hydroxyethyl acrylate/benzoyl peroxide (50/40/10/2) mixture. The addition of PVAc did not give much influence to the degree of impregnation in the veneer and to the curability by electron beam irradiation. As to the resistance to hot and cold cycle test, WPC piled plywood, prepared by the resin containing 5 parts of PVAc gave the best results. As a general conclusion, due to the superior mechanical properties, the WPC piled plywood processed by electron beam irradiation is suitable for flooring use. (author)

Preparation of supramolecular polymers by copolymerization of monomers containing quadruple hydrogen bonding units with regular monomers

NARCIS (Netherlands)

2004-01-01

The invention relates to the synthesis of polymers contg. self-complementary quadruple H groups by copolymg. monomers contg. a quadruple H bonding group with ³1 monomers of choice. The resulting polymers show unique new characteristics due to the presence of addnl. phys. interactions between the

The Effect of Simplified Bonding Agents on the Bond Strength to Dentin of Self-Activated Dual-Cure Resin Cements

Science.gov (United States)

2013-04-26

steps that included an acidic conditioner, primer, and adhesive monomer. Examples include Optibond FL (Kerr) and Adper Scotchbond MultiPurpose ( 3M ESPE...Bond NT (Dentsply) and Adper Prompt L-Pop ( 3M /ESPE); and two non-simplified adhesives , Optibond FL (Kerr) and Clearfil SE (Kuraray). The four...presentation at the 2013 IADR by Bisco Inc. compared their simplified adhesive and self-cure resin combination All-Bond Universal and Duolink with

Evaluation of the polymerization shrinkage of experimental flowable composite resins through optical coherence tomography

Science.gov (United States)

Carneiro, Vanda S. M.; Mota, Cláudia C. B. O.; Souza, Alex F.; Cajazeira, Marlus R. R.; Gerbi, Marleny E. M. M.; Gomes, Anderson S. L.

2018-02-01

This study evaluated the polymerization shrinkage of two experimental flowable composite resins (CR) with different proportions of Urethane dimethacrylate (UDMA)/triethylene glycol dimethacrylate (TEGDMA) monomers in the organic matrix (50:50 and 60:40, respectively). A commercially available flowable CR, Tetric N-Flow (Ivoclair Vivadent, Liechtenstein, Germany), was employed as the control group. The resins were inserted in a cylindrical teflon mold (7 mm diameter, 0.6 mm height) and scanned with OCT before photoactivation, immediately after and 15 minutes after light-curing (Radii-Cal, SDI, Australia, 1,200 mW/cm2 ) exposure. A Callisto SD-OCT system (Thorlabs Inc, USA), operating at 930 nm central wavelength was employed for imaging acquisition. Cross-sectional OCT images were captured with 8 mm transverse scanning (2000x512 matrix), and processed by the ImageJ software, for comparison between the scanning times and between groups. Pearson correlation showed significant shrinkage for all groups in each time analyzed. Kruskal-Wallis test showed greater polymerization shrinkage for the 50:50 UDMA/TEGDMA group (p=0.001), followed by the control group (p=0.018). TEGDMA concentration was proportionally related to the polymerization shrinkage of the flowable composite resins.

Immobilization of spent resin with epoxy resin

International Nuclear Information System (INIS)

Gultom, O.; Suryanto; Sayogo; Ramdan

1997-01-01

immobilization of spent resin using epoxy resin has been conducted. The spent resin was mixtured with epoxy resin in variation of concentration, i.e., 30, 40, 50, 60, 70 weight percent of spent resin. The mixture were pour into the plastic tube, with a diameter of 40 mm and height of 40 mm. The density, compressive strength and leaching rate were respectively measured by quanta chrome, paul weber apparatus and gamma spectrometer. The results showed that the increasing of waste concentration would be decreased the compressive strength, and increased density by immobilized waste. The leaching rate of 137 Cs from waste product was not detected in experiment (author)

Photo-polymerization of photocurable resins containing polyhedral oligomeric silsesquioxane methacrylate

International Nuclear Information System (INIS)

Lin, Ho-May; Wu, Shi-Yin; Chang, Feng-Chih; Yen, Ying-Chieh

2011-01-01

Photocurable resins, bisphenol A propoxylate glycerolate diacrylate (BPA-PGDA, containing two hydroxyl) and bisphenol A propoxylate diacrylate (BPA-PDA), with fixed photoinitiator (Irgacure 907) concentration and various contents of methacrylisobutyl polyhedral oligomeric silsesquioxane (MI-POSS) were prepared and characterized by FTIR spectroscopy, scanning electron microscope and differential photocalorimetry. The MI-POSS molecules form crystals or aggregated particles in the cured resin matrix. The BPA-PGDA series photocurable resins show higher viscosity and lower photo-polymerization reactivity than the BPA-PDA series resins. The photo-polymerization rate and conversion of BPA-PGDA series are improved with increasing MI-POSS content. On the contrary, the photo-polymerization behavior of BPA-PDA series photocurable resins remains nearly unchanged by the addition of MI-POSS. Hydrogen-bonding interaction between the hydroxyl of BPA-PGDA and the siloxane of MI-POSS tends to attract and concentrate these acrylate double bonds around MI-POSS particles and thus enhances the photo-polymerization rate and conversion.

Qualitative Beam Profiling of Light Curing Units for Resin Based Composites.

Science.gov (United States)

Haenel, Thomas; Hausnerová, Berenika; Steinhaus, Johannes; Moeginger, Ing Bernhard

2016-12-01

This study investigates two technically simple methods to determine the irradiance distribution of light curing units that governs the performance of a visible-light curing resin-based composites. Insufficient light irradiation leads to under-cured composites with poor mechanical properties and elution of residual monomers. The unknown irradiance distribution and its effect on the final restoration are the main critical issues requiring highly sophisticated experimental equipment. The study shows that irradiance distributions of LCUs can easily be determined qualitatively with generally available equipment. This significantly helps dentists in practices to be informed about the homogeneity of the curing lights. Copyright© 2016 Dennis Barber Ltd.

Interference of functional monomers with polymerization efficiency of adhesives.

Science.gov (United States)

Hanabusa, Masao; Yoshihara, Kumiko; Yoshida, Yasuhiro; Okihara, Takumi; Yamamoto, Takatsugu; Momoi, Yasuko; Van Meerbeek, Bart

2016-04-01

The degree of conversion (DC) of camphorquinone/amine-based adhesives is affected by acidic functional monomers as a result of inactivation of the amine co-initiator through an acid-base reaction. During bonding, functional monomers of self-etch adhesives chemically interact with hydroxyapatite (HAp). Here, we tested in how far the latter interaction of functional monomers with HAp counteracts the expected reduction in DC of camphorquinone/amine-based adhesives. The DC of three experimental adhesive formulations, containing either of the two functional monomers [10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) or 4-methacryloxyethyl trimellitic acid anhydride (4-META)] or no functional monomer (no-FM; control), was measured with and without HAp powder added to the adhesive formulations. Both the variables 'functional monomer' and 'HAp' were found to be significant, with the functional monomer reducing the DC and HAp counteracting this effect. It is concluded that the functional monomers 10-MDP and 4-META interfere with the polymerization efficiency of adhesives. This interference is less prominent in the presence of HAp, which would clinically correspond to when these two functional monomers of the adhesive simultaneously interact with HAp in tooth tissue. © 2016 Eur J Oral Sci.

The effect of polymerization mode on monomer conversion, free radical entrapment, and interaction with hydroxyapatite of commercial self-adhesive cements.

Science.gov (United States)

D'Alpino, Paulo Henrique Perlatti; Silva, Marília Santos; Vismara, Marcus Vinícius Gonçalves; Di Hipólito, Vinicius; Miranda González, Alejandra Hortencia; de Oliveira Graeff, Carlos Frederico

2015-06-01

This study evaluated the degree of conversion, the free radical entrapment, and the chemical interaction of self-adhesive resin cements mixed with pure hydroxyapatite, as a function of the polymerization activation mode among a variety of commercial self-adhesive cements. Four cements (Embrace WetBond, MaxCem Elite, Bifix SE, and RelyX U200) were mixed, combined with hydroxyapatite, dispensed into molds, and distributed into three groups, according to polymerization protocols: IP (photoactivation for 40s); DP (delayed photoactivation, 10 min self-curing plus 40s light-activated); and CA (chemical activation, no light exposure). Infrared (IR) spectra were obtained and monomer conversion (%) was calculated by comparing the aliphatic-to-aromatic IR absorption peak ratio before and after polymerization (n=10). The free radical entrapment values of the resin cements were characterized using Electron Paramagnetic Resonance (EPR) and the concentration of spins (number of spins/mass) calculated (n=3). Values were compared using two-way ANOVA and Tukey's post-hoc test (α=5%). X-ray diffraction (XRD) characterized the crystallinity of hydroxyapatite as a function of the chemical interactions with the resin cements. The tested parameters varied as a function of resin cement and polymerization protocol. Embrace WetBond and RelyX U200 demonstrated dependence on photoactivation (immediate or delayed), whereas MaxCem Elite exhibited dependence on the chemical activation mode. Bifix SE presented the best balance based on the parameters analyzed, irrespective of the activation protocol. Choice of polymerization protocol affects the degree of conversion, free radical entrapment, and the chemical interaction between hydroxyapatite and self-adhesive resin cement mixtures. Copyright © 2015 Elsevier Ltd. All rights reserved.

Oligonucleotides with 1,4-dioxane-based nucleotide monomers

DEFF Research Database (Denmark)

Madsen, Andreas S; Wengel, Jesper

2012-01-01

An epimeric mixture of H-phosphonates 5R and 5S has been synthesized in three steps from known secouridine 1. Separation of the epimers has been accomplished by RP-HPLC, allowing full characterization and incorporation of monomers X and Y into 9-mer oligonucleotides using H-phosphonates building...... blocks 5R and 5S, respectively. A single incorporation of either monomer X or monomer Y in the central position of a DNA 9-mer results in decreased thermal affinity toward both DNA and RNA complements (ΔT(m) = -3.5 °C/-3.5 °C for monomer X and ΔT(m) = -11.0 °C/-6.5 °C for monomer Y). CD measurements do...

Surface active monomers synthesis, properties, and application

CERN Document Server

Borzenkov, Mykola

2014-01-01

This brief includes information on the background?of and development of synthesis of various types of surface active monomers. The authors explain the importance of utilization of surface active monomers for creation of surface active polymers? and the various biomedical applications of such compounds . This brief introduces techniques for the synthesis of novel types of surface active monomers, their colloidal and polymerizable properties and application for needs of medicine and biology.

Single Low-Dose Radiation Induced Regulation of Keratinocyte Differentiation in Calcium-Induced HaCaT Cells

Science.gov (United States)

Hahn, Hyung Jin; Youn, Hae Jeong; Cha, Hwa Jun; Kim, Karam; An, Sungkwan

2016-01-01

Background We are continually exposed to low-dose radiation (LDR) in the range 0.1 Gy from natural sources, medical devices, nuclear energy plants, and other industrial sources of ionizing radiation. There are three models for the biological mechanism of LDR: the linear no-threshold model, the hormetic model, and the threshold model. Objective We used keratinocytes as a model system to investigate the molecular genetic effects of LDR on epidermal cell differentiation. Methods To identify keratinocyte differentiation, we performed western blots using a specific antibody for involucrin, which is a precursor protein of the keratinocyte cornified envelope and a marker for keratinocyte terminal differentiation. We also performed quantitative polymerase chain reaction. We examined whether LDR induces changes in involucrin messenger RNA (mRNA) and protein levels in calcium-induced keratinocyte differentiation. Results Exposure of HaCaT cells to LDR (0.1 Gy) induced p21 expression. p21 is a key regulator that induces growth arrest and represses stemness, which accelerates keratinocyte differentiation. We correlated involucrin expression with keratinocyte differentiation, and examined the effects of LDR on involucrin levels and keratinocyte development. LDR significantly increased involucrin mRNA and protein levels during calcium-induced keratinocyte differentiation. Conclusion These studies provide new evidence for the biological role of LDR, and identify the potential to utilize LDR to regulate or induce keratinocyte differentiation. PMID:27489424

Evaluation of three different decontamination techniques on biofilm formation, and on physical and chemical properties of resin composites.

Science.gov (United States)

André, Carolina Bosso; Dos Santos, Andressa; Pfeifer, Carmem Silvia; Giannini, Marcelo; Girotto, Emerson Marcelo; Ferracane, Jack Liborio

2018-04-01

This study evaluated three different sterilization/disinfection techniques for resin composites on bacterial growth and surface modification after decontamination. Two resin composites were sterilized/disinfected with three different techniques: UV light, 1% chloramine T, and 70% ethanol. Four different times were used for each technique to determine the shortest time that the solution or UV light was effective. The influence of sterilization/disinfection technique on bacterial growth was evaluated by analyzing the metabolic activity, using the AlamarBlue™ assay, bacterial viability, and SEM images from biofilms of Streptococcus mutans. The surface change, after the process, was analyzed with ATR/FTIR and SEM images. The solutions used for decontamination (1% chloramine-T and 70% ethanol) were analyzed with 1 H-NMR to identify any resin compounds leached during the process. One minute of decontamination was efficient for all three methods tested. Chloramine-T increased the surface porosity on resin composites, no changes were observed for UV light and 70% ethanol, however, 1 H-NMR identified leached monomers only when 70% ethanol was used. No chemical change of the materials was found under ATR/FTIR analyses after the decontamination process. Chloramine-T, with no previous wash, increased the bacterial viability for both resin composites and increased the bacterial metabolism for the resin composite without fluoride. UV light had no interference on the resin composites properties tested using 1 min of exposure compared to the other decontamination methods. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 945-953, 2018. © 2017 Wiley Periodicals, Inc.

Resin impregnation process for producing a resin-fiber composite

Science.gov (United States)

Palmer, Raymond J. (Inventor); Moore, William E. (Inventor)

1994-01-01

Process for vacuum impregnation of a dry fiber reinforcement with a curable resin to produce a resin-fiber composite, by drawing a vacuum to permit flow of curable liquid resin into and through a fiber reinforcement to impregnate same and curing the resin-impregnated fiber reinforcement at a sufficient temperature and pressure to effect final curing. Both vacuum and positive pressure, e.g. autoclave pressure, are applied to the dry fiber reinforcement prior to application of heat and prior to any resin flow to compact the dry fiber reinforcement, and produce a resin-fiber composite of reduced weight, thickness and resin content, and improved mechanical properties. Preferably both a vacuum and positive pressure, e.g. autoclave pressure, are also applied during final curing.

Integrin-linked kinase is involved in matrix-induced hepatocyte differentiation

International Nuclear Information System (INIS)

Gkretsi, Vasiliki; Bowen, William C.; Yang, Yu; Wu, Chuanyue; Michalopoulos, George K.

2007-01-01

Hepatocytes have restricted proliferative capacity in culture and when cultured without matrix, lose the hepatocyte-specific gene expression and characteristic cellular micro-architecture. Overlay of matrix-preparations on de-differentiated hepatocytes restores differentiation. Integrin-linked kinase (ILK) is a cell-matrix-adhesion protein crucial in fundamental processes such as differentiation and survival. In this study, we investigated the role of ILK, and its binding partners PINCH, α-parvin, and Mig-2 in matrix-induced hepatocyte differentiation. We report here that ILK is present in the liver and localizes at cell-matrix adhesions of cultured hepatocytes. We also show that ILK, PINCH, α-parvin, and Mig-2 expression level is dramatically reduced in the re-differentiated hepatocytes. Interestingly, hepatocytes lacking ILK undergo matrix-induced differentiation but their differentiation is incomplete, as judged by monitoring cell morphology and production of albumin. Our results show that ILK and cell-matrix adhesion proteins play an important role in the process of matrix-induced hepatocyte differentiation

Efficacy of polishing kits on the surface roughness and color stability of different composite resins.

Science.gov (United States)

Kocaagaoglu, H; Aslan, T; Gürbulak, A; Albayrak, H; Taşdemir, Z; Gumus, H

2017-05-01

Different polishing kits may have different effects on the composite resin surfaces. The aim of this study was to evaluate the surface roughness and color stability of four different composites which was applied different polishing technique. Thirty specimens were made for each composite resin group (nanohybrid, GrandioSo-GS; nanohybrid, Clearfil Majesty Esthetic-CME; hybrid, Valux Plus-VP; micro-hybrid, Ruby Comp-RC; [15 mm in diameter and 2 mm height]), with the different monomer composition and particle size from a total of 120 specimens. Each composite group was divided into three subgroups (n = 10). The first subgroup of the each composite subgroups served as control (C) and had no surface treatment. The second subgroup of the each composite resin groups was polished with finishing discs (Bisco Finishing Discs; Bisco Inc., Schaumburg, IL, USA). The third subgroup of the each composite resin was polished with polishing wheel (Enhance and PoGo, Dentsply, Konstanz, Germany). The surface roughness and the color differences measurement of the specimens were made and recorded. The data were compared using Kruskal-Wallis test, and regression analysis was used in order to examine the correlation between surface roughness and color differences of the specimens (α = 0.05). The Kruskal-Wallis test indicated significant difference among the composite resins in terms of ΔE (P composite resins in terms of surface roughness (P > 0.05). Result of the regression analysis indicated statistically significant correlation between Ra and ΔE values (P < 0.05, r2 = 0.74). The findings of the present study have clinical relevance in the choice of polishing kits used.

Two-photon polymerization of metal ions doped acrylate monomers and oligomers for three-dimensional structure fabrication

International Nuclear Information System (INIS)

Duan Xuanming; Sun Hongbo; Kaneko, Koshiro; Kawata, Satoshi

2004-01-01

We have investigated two-photon polymerization of metal ions doped acrylate monomers and oligomers which is applied for three-dimensional (3D) micro/nano-structure fabrication. Titanium (IV) ions doped urethane acrylate photopolymerizable resins were synthesized, and their optical and polymerization properties were investigated. The resolution of two-photon polymerization for micro/nanofabrication was evaluated. Titanium dioxide (TiO 2 ) nanoparticles were generated in the polymer matrix of micron-sized polymer structures. A 3D diamond photonic crystal structure, which consisted of polymer composite materials of TiO 2 nanoparticles, was successfully fabricated by direct laser writing and its photonic bandgap was confirmed. This work would give us a new solution for producing 3D micro/nanodevices of functional polymer composite materials

On Volatility Induced Stationarity for Stochastic Differential Equations

DEFF Research Database (Denmark)

Albin, J.M.P.; Astrup Jensen, Bjarne; Muszta, Anders

2006-01-01

This article deals with stochastic differential equations with volatility induced stationarity. We study of theoretical properties of such equations, as well as numerical aspects, together with a detailed study of three examples.......This article deals with stochastic differential equations with volatility induced stationarity. We study of theoretical properties of such equations, as well as numerical aspects, together with a detailed study of three examples....

Synergetic interaction between neighbouring platinum monomers in CO2 hydrogenation

Science.gov (United States)

Li, Hongliang; Wang, Liangbing; Dai, Yizhou; Pu, Zhengtian; Lao, Zhuohan; Chen, Yawei; Wang, Menglin; Zheng, Xusheng; Zhu, Junfa; Zhang, Wenhua; Si, Rui; Ma, Chao; Zeng, Jie

2018-05-01

Exploring the interaction between two neighbouring monomers has great potential to significantly raise the performance and deepen the mechanistic understanding of heterogeneous catalysis. Herein, we demonstrate that the synergetic interaction between neighbouring Pt monomers on MoS2 greatly enhanced the CO2 hydrogenation catalytic activity and reduced the activation energy relative to isolated monomers. Neighbouring Pt monomers were achieved by increasing the Pt mass loading up to 7.5% while maintaining the atomic dispersion of Pt. Mechanistic studies reveal that neighbouring Pt monomers not only worked in synergy to vary the reaction barrier, but also underwent distinct reaction paths compared with isolated monomers. Isolated Pt monomers favour the conversion of CO2 into methanol without the formation of formic acid, whereas CO2 is hydrogenated stepwise into formic acid and methanol for neighbouring Pt monomers. The discovery of the synergetic interaction between neighbouring monomers may create a new path for manipulating catalytic properties.

21 CFR 888.4220 - Cement monomer vapor evacuator.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cement monomer vapor evacuator. 888.4220 Section... (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Surgical Devices § 888.4220 Cement monomer vapor evacuator. (a) Identification. A cement monomer vapor evacuator is a device intended for use during surgery to contain or remove...

Thermodynamically stable amyloid-β monomers have much lower membrane affinity than the small oligomers

Directory of Open Access Journals (Sweden)

Bidyut eSarkar

2013-04-01

Full Text Available Amyloid beta (Aβ is an extracellular 39-43 residue long peptide present in the mammalian cerebrospinal fluid, whose aggregation is associated with Alzheimer’s disease. Small oligomers of Aβ are currently thought to be the key to toxicity. However, it is not clear why the monomers of Aβ are non-toxic, and at what stage of aggregation toxicity emerges. Interactions of Aβ with cell membranes is thought to be the initiator of toxicity, but membrane-binding studies with different preparations of monomers and oligomers have not settled this issue. We have earlier found that thermodynamically stable Aβ monomers emerge spontaneously from oligomeric mixtures upon long term incubation in physiological solutions (Nag et al, JBC, 2011. Here we show that the membrane-affinity of these stable Aβ monomers is much lower than that of a mixture of small oligomers (containing dimers to decamers, providing a clue to the emergence of toxicity. Fluorescently labeled Aβ40 monomers show negligible binding to cell membranes of a neuronal cell line (RN46A at physiological concentrations (250 nM, while oligomers at the same concentrations show strong binding within 30 minutes of incubation. The increased affinity most likely does not require any specific neuronal receptor, since this difference in membrane-affinity was also observed in a somatic cell-line (HEK 293T. Similar results are also obtained for Aβ42 monomers and oligomers. Minimal amount of cell death is observed at these concentrations even after 36 hours of incubation. It is likely that membrane binding precedes subsequent slower toxic events induced by Aβ. Our results a provide an explanation for the non-toxic nature of Aβ monomers, b suggest that Aβ toxicity emerges at the initial oligomeric phase, and c provide a quick assay for monitoring the benign-to-toxic transformation of Aβ.

Ion exchange resins as high-dose radiation dosimeters

International Nuclear Information System (INIS)

Alian, A.; Dessouki, A.; El-Assay, N.B.

1984-01-01

This paper reports on the possibility of using various types of ion exchange resins as high-dose radiation dosimeters, by analysis of the decrease in exchange capacity with absorbed dose. The resins studied are Sojuzchim-export-Moscow Cation Exchanger KU-2 and Anion Exchanger AV-17 and Merck Cation Exchanger I, and Merck Anion Exchangers II and III. Over the dose range 1 to 100 kGy, the systems show linearity between log absorbed dose and decrease in resin ion exchange capacity. The slope of this response function differs for the different resins, depending on their ionic form and degree of cross-linking. The radiation sensitivity increases in the order KU-2; Exchanger I; AV-17; Exchanger II; Exchanger III. Merck resins with moisture content of 21% showed considerably higher radiation sensitivity than those with 2 to 3% moisture content. The mechanism of radiation-induced denaturing of the ion exchanger resins involves cleavage and decomposition of functional substituents, with crosslinking playing a stabilizing role, with water and its radiolytic products serving to inhibit radical recombination and interfering with the protection cage effect of crosslinking. (author)

Microarray analysis of the gene expression profile in triethylene glycol dimethacrylate-treated human dental pulp cells.

Science.gov (United States)

Torun, D; Torun, Z Ö; Demirkaya, K; Sarper, M; Elçi, M P; Avcu, F

2017-11-01

Triethylene glycol dimethacrylate (TEGDMA) is an important resin monomer commonly used in the structure of dental restorative materials. Recent studies have shown that unpolymerized resin monomers may be released into the oral environment and cause harmful biological effects. We investigated changes in the gene expression profiles of TEGDMA-treated human dental pulp cells (hDPCs) following short- (1-day) and long-term (7-days) exposure. HDPCs were exposed to a noncytotoxic concentration of TEGDMA, and gene expression profiles were evaluated by microarray analysis. The results were confirmed by quantitative reverse-transcriptase PCR (qRT PCR). In total, 1282 and 1319 genes (up- or down-regulated) were differentially expressed compared with control group after the 1- and 7-day incubation periods, respectively. Biological ontology-based analyses revealed that metabolic, cellular, and developmental processes constituted the largest groups of biological functional processes. qRT-PCR analysis on bone morphogenetic protein-2 (BMP-2), BMP-4, secreted protein, acidic, cysteine-rich, collagen type I alpha 1, oxidative stress-induced growth inhibitor 1, MMP3, interleukin-6, and heme oxygenase-1 genes confirmed the changes in expression observed in the microarray analysis. Our results suggest that TEGDMA can change the many functions of hDPCs through large changes in gene expression levels and complex interactions with different signaling pathways.

Gamma Radiation -Induced Preparation of Polymeric Composite Resins and their Structure Assignments

International Nuclear Information System (INIS)

El-Zahhar, A.A.; Abdel-Aziz, H.M.; Siyam, T.

2005-01-01

Poly(acrylamide-acrylic acid). ethylenediamine tetra acetic acid disodium salt P(AM-AA). EDTANa2, Poly(acrylamide-acrylic acid)montmorillonite P(AM-AA). montmorillonite, and Poly(acrylamide acrylic acid)-potassium nickel hexacyanoferrate P(AM-AA)-KNiHCF were prepared by gamma radiation- induced template polymerization of (AA) on P(AM) as a template polymer in the presence of EDTANa2, Clay(montmorillonite), KNiHCF and KZnHCF, respectively. The capacity of the prepared P (AM-AA)-EDTANa2 and P (AM-AA)-montmorillonite composites increases with increasing of EDTANa2 and montmorillonite concentration then decreases. While the capacity of P(AM- AA). KNiHCF composites increases with increasing of KNiHCF content. The characteristic properties of prepared polymeric composites resins were studied by using FTIR spectroscopy

A resin composite material containing an eugenol derivative for intracanal post cementation and core build-up restoration.

Science.gov (United States)

Almaroof, A; Rojo, L; Mannocci, F; Deb, S

2016-02-01

To formulate and evaluate new dual cured resin composite based on the inclusion of eugenyl methacrylate monomer (EgMA) with Bis-GMA/TEGDMA resin systems for intracanal post cementation and core build-up restoration of endodontically treated teeth. EgMA was synthesized and incorporated at 5% (BTEg5) or 10% (BTEg10) into dual-cure formulations. Curing properties, viscosity, Tg, radiopacity, static and dynamic mechanical properties of the composites were determined and compared with Clearfil™DC Core-Plus, a commercial dual-cure, two-component composite. Statistical analysis of the data was performed with ANOVA and the Tukey's post-hoc test. The experimental composites were successfully prepared, which exhibited excellent curing depths of 4.9, 4.7 and 4.2 mm for BTEg0, BTEg5 and BTEg10 respectively, which were significantly higher than Clearfil™DC. However, the inclusion of EgMA initially led to a lower degree of cure, which increased when measured at 24 h with values comparable to formulations without EgMA, indicating post-curing. The inclusion of EgMA also lowered the polymerization exotherm thereby reducing the potential of thermal damage to host tissue. Both thermal and viscoelastic analyses confirmed the ability of the monomer to reduce the stiffness of the composites by forming a branched network. The compressive strength of BTEg5 was significantly higher than the control whilst flexural strength increased significantly from 95.9 to 114.8 MPa (BTEg5) and 121.9 MPa (BTEg10). Radiopacity of the composites was equivalent to ∼3 mm Al allowing efficient diagnosis. The incorporation of EgMA within polymerizable formulations provides a novel approach to prepare reinforced resin composite material for intracanal post cementation and core build-up and the potential to impart antibacterial properties of eugenol to endodontic restorations. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Lactate induces osteoblast differentiation by stabilization of HIF1α.

Science.gov (United States)

Wu, Yu; Wang, Miaomiao; Feng, Haihua; Peng, Ying; Sun, Jieyun; Qu, Xiuxia; Li, Chunping

2017-09-05

Aerobic glycolysis is involved in osteoblast differentiation induced by Wnt signaling or PTH treatment. However, it is still unclear whether lactate, the end product of aerobic glycolysis, plays any role in osteoblast differentiation. Herein we report that in cultures of osteoblast-lineage cells, lactate promoted alkaline phosphatase-positive cell formation, increased the activity of alkaline phosphatase, and induced the expression of osteocalcin. This osteoblast differentiation-inducing effect of lactate can be inhibited by blocking its entry into cells with MCT1 siRNA or inhibitors, and by interfering with its metabolism by using specific siRNAs for LDHB and PDH. Moreover, lactate stabilized HIF1α expression and inhibited HIF1α activity, with BAY87-2243 lowering the osteoblast differentiation-inducing effect of lactate. Thus, these findings reveal an unrecognized role for aerobic glycolysis in osteoblast differentiation via its end product, lactate. Copyright © 2017 Elsevier B.V. All rights reserved.

Adsorption of uranium ions by crosslinked polyester resin functionalized with acrylic acid from aqueous solutions

International Nuclear Information System (INIS)

Cemal Oezeroglu; Niluefer Metin

2012-01-01

In this paper, the crosslinked polyester resin containing acrylic acid functional groups was used for the adsorption of uranium ions from aqueous solutions. For this purpose, the crosslinked polyester resin of unsaturated polyester in styrene monomer (Polipol 353, Poliya) and acrylic acid as weight percentage at 80 and 20%, respectively was synthesized by using methyl ethyl ketone peroxide (MEKp, Butanox M60, Azo Nobel)-cobalt octoate initiator system. The adsorption of uranium ions on the sample (0.05 g copolymer and 5 mL of U(VI) solution were mixed) of the crosslinked polyester resin functionalized with acrylic acid was carried out in a batch reactor. The effects of adsorption parameters of the contact time, temperature, pH of solution and initial uranium(VI) concentration for U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid were investigated. The adsorption data obtained from experimental results depending on the initial U(VI) concentration were analyzed by the Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption isotherms. The adsorption capacity and free energy change were determined by using D-R isotherm. The obtained experimental adsorption data depending on temperature were evaluated to calculate the thermodynamic parameters of enthalpy (ΔH o ), entropy (ΔS o ) and free energy change (ΔG o ) for the U(VI) adsorption on the crosslinked polyester resin functionalized with acrylic acid from aqueous solutions. The obtained adsorption data depending on contact time were analyzed by using adsorption models such as the modified Freundlich, Elovich, pseudo-first order and pseudo-second-order kinetic models. (author)

Highly Efficient Synthesis of Allopurinol Locked Nucleic Acid Monomer by C6 Deamination of 8-Aza-7-bromo-7-deazaadenine Locked Nucleic Acid Monomer

DEFF Research Database (Denmark)

Kosbar, Tamer Reda El-Saeed; Sofan, M.; Abou-Zeid, L.

2013-01-01

An allopurinol locked nucleic acid (LNA) monomer was prepared by a novel strategy through C6 deamination of the corresponding 8-aza-7-bromo-7-deazaadenine LNA monomer with aqueous sodium hydroxide. An 8-aza-7-deazaadenine LNA monomer was also synthesized by a modification of the new synthetic...... the required LNA monomers....

Copolymerization of carbon monoxide and styrene catalyzed by resin-supported palladium polymer

Directory of Open Access Journals (Sweden)

2007-02-01

Full Text Available Polyketone was prepared by the copolymerization of carbon monoxide (CO and styrene (ST catalyzed by o-phenylenediamine resin-supported palladium acetate. Effects of each catalytic system component such as 2,2’-bipyridine, 1,4-quinone and p-toluene-sulphonate on the copolymerization were investigated. The resin-supported catalyst and the copolymerization product were characterized by infrared spectroscopy (IR, differential scanning calorimetry (DSC, thermogravimetry (TG, X-ray photoelectron spectroscopy (XPS, Scanning Electron Microscopy (SEM. Results indicated that the resin-supported catalyst has excellent catalytic property. Furthermore, partial catalytic activity was maintained after the catalyst was used for five times.

Condensate-polisher resin-leakage quantification and resin-transport studies

International Nuclear Information System (INIS)

Stauffer, C.C.; Doss, P.L.

1983-04-01

The objectives of this program were to: (1) determine the extent of resin leakage from current generation condensate polisher systems, both deep bed and powdered resin design, during cut-in, steady-state and flow transient operation, (2) analyze moisture separator drains and other secondary system samples for resin fragments and (3) document the level of organics in the secondary system. Resin leakage samples were obtained from nine-power stations that have either recirculating steam generators or once through steam generators. Secondary system samples were obtained from steam generator feedwater, recirculating steam generator blowdown and moisture separator drains. Analysis included ultraviolet light examination, SEM/EDX, resin quantification and infrared analysis. Data obtained from the various plants were compared and factors affecting resin leakage were summarized

Shock-induced electrical activity in polymeric solids. A mechanically induced bond scission model

International Nuclear Information System (INIS)

Graham, R.A.

1979-01-01

When polymeric solids are subjected to high-pressure shock loading, two anomalous electrical phenomena, shock-induced conduction and shock-induced polarization, are observed. The present paper proposes a model of mechanically induced bond scission within the shock front to account for the effects. An experimental study of shock-induced polarization in poly(pyromellitimide) (Vespel SP-1) is reported for shock compressions from 17 to 23% (pressures from 2.5 to 5.4 GPa). Poly(pyromellitimide) is found to be a strong generator of such polarization and the polarization is found to reflect an irreversible or highly hysteretic process. The present measurements are combined with prior measurements to establish a correlation between monomer structure and strength of shock-induced polarization; feeble signals are observed in the simpler monomer repeat units of poly(tetrafluoroethylene) and polyethylene while the strongest signals are observed in more complex monomers of poly(methyl methacrylate) and poly(pyromellitimide). It is also noted that there is an apparent correlation between shock-induced conduction and shock-induced polarization. Such shock-induced electrical activity is also found to be well correlated with the propensity for mechanical bond scission observed in experiments carried out in conventional mechanochemical studies. The bond scission model can account for characteristics observed for electrical activity in shock-loaded polymers and their correlation to monomer structure. Localization of elastic energy within the monomer repeat unit or along the main chain leads to the different propensities for bond scission and resulting shock-induced electrical activity

Photothermal radiometric determination of thermal diffusivity depth profiles in a dental resin

International Nuclear Information System (INIS)

MartInez-Torres, P; Alvarado-Gil, J J; Mandelis, A

2010-01-01

The depth of curing due to photopolymerization in a commercial dental resin is studied using photothermal radiometry. The sample consists of a thick layer of resin on which a thin metallic layer is deposited guaranteeing full opacity of the sample. In this case, purely thermal-wave inverse problem techniques without the interference of optical profiles can be used. Thermal profiles are obtained by heating the coating with a modulated laser beam and performing a modulation frequency scan. Before each frequency scan, photopolymerization was induced using a high power blue LED. However due to the fact that dental resins are highly light dispersive materials, the polymerization process depends strongly on the optical absorption coefficient inducing a depth dependent thermal diffusion in the sample. It is shown that using a robust depth profilometric inverse method one can reconstruct the thermal diffusivity profile of the photopolymerized resin.

Surface coating of jeungjing wood (Paraserianthes Falcataria (L) NIELSEN) with acrylate resins by using radiation technique

International Nuclear Information System (INIS)

Suhariyono, Gatot

1998-01-01

An experiment on surface coating with acrylate resins has been done by using radiation technique to improve the quality and added value of jeunjing wood (Paraserianthes Falcataria (L) NIELSEN). Doses used in Electron Beam (BE) radiation were 20, 40, and 60 kGy. Epoxy acrylate and ester acrylate resins were used as coating materials after added with tripropylene glycol diacylate (TPGDA) monomer, 2,2-dimethyl-2hidroxy acetophenone (Darocur 1173) photoinitiator and talc as base coat. Top coat consists of este acrylate Setacure AM 548, after added with titanium dioxide OK 412 as additive respectively. Titanium dioxides in the mixture were varied at the concentration level of 0, 2, 4 and 6 % by weight. Conventional coating as comparison was carried out by using varnish as coating material. The results showed that the properties of film on jeunjing wood by EB curing are better than that of conventional one. (authors)

Pseudomonas syringae evades host immunity by degrading flagellin monomers with alkaline protease AprA

NARCIS (Netherlands)

Pel, Michiel J C; van Dijken, Anja J H; Bardoel, Bart W; Seidl, Michael F; van der Ent, Sjoerd; van Strijp, Jos A G; Pieterse, Corné M J

Bacterial flagellin molecules are strong inducers of innate immune responses in both mammals and plants. The opportunistic pathogen Pseudomonas aeruginosa secretes an alkaline protease called AprA that degrades flagellin monomers. Here, we show that AprA is widespread among a wide variety of

Pseudomonas syringae evades host Immunity by degrading flagellin monomers with alkaline protease AprA

NARCIS (Netherlands)

Pel, M.J.C.; Van Dijken, A.J.H.; Bardoel, B.W.; Seidl, M.F; Van der Ent, S.; Van Strijp, J.A.G.

2014-01-01

Bacterial flagellin molecules are strong inducers of innate immune responses in both mammals and plants. The opportunistic pathogen Pseudomonas aeruginosa secretes an alkaline protease called AprA that degrades flagellin monomers. Here, we show that AprA is widespread among a wide variety of

Thermal properties and corrosion resistance of organoclay/epoxy resin film

Science.gov (United States)

Baiquni, M.; Soegijono, B.

2018-03-01

Hybrid materials organoclay/epoxy resin films were prepared by varying organoclay content in epoxy resin as a matrix. The film were investigated by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermal conductivity. TGA and FT-IR results confirmed that the melting temperature shifted to a lower point. The thermal conductivity and corrosion resistant generally increase with increasing organoclay content. The changes on these properties may due to cross link between organoclay and epoxy.

Characterization of γ-radiation induced polymerization in ethyl methacrylate and methyl acrylate monomers solutions

Science.gov (United States)

Baccaro, Stefania; Casieri, Cinzia; Cemmi, Alessia; Chiarini, Marco; D'Aiuto, Virginia; Tortora, Mariagrazia

2017-12-01

The present work is focused on the γ-radiation induced polymerization of ethyl methacrylate (EMA) and methyl acrylate (MA) monomers mixture to obtain a co-polymer with specific features. The effect of the irradiation parameters (radiation absorbed dose, dose rate) and of the environmental atmosphere on the features of the final products was investigated. Attenuated Total Reflectance - Fourier Transform Infrared Spectroscopy (ATR-FTIR) and Nuclear Magnetic Resonance high-resolution analyses of hydrogen and carbon nuclei (1H and 13C NMR) were applied to follow the γ-induced modifications by monitoring the co-polymerization process and allowed the irradiation parameters optimization. Diffusion-Ordered NMR (DOSY-NMR) data were used to evaluate the co-polymers polydispersity and polymerization degree. Since the last parameter is strongly influenced by the γ radiation and environmental conditions, a comparison among samples prepared and irradiated in air and under nitrogen atmosphere was carried out. In presence of oxygen, higher radiation was required to obtain a full solid co-polymer since a partial amount of energy released to the samples was involved in competitive processes, i.e. oxygen-containing free radicals formation and primary radicals recombination. Irrespectively to the environmental atmosphere, more homogeneous samples in term of polymerization degree dispersion was achieved at lower dose rates. At radiation absorbed doses higher than those needed for the formation of the co-polymer, while in case of samples irradiated in air heavy depolymerization was verified, a sensible increase of the samples stability was attained if the irradiation was performed under nitrogen atmosphere.

Polymerization and curing kinetics of furan resins under conventional and microwave heating

International Nuclear Information System (INIS)

Lopez de Vergara, Unai; Sarrionandia, Mariasun; Gondra, Koldo; Aurrekoetxea, Jon

2014-01-01

Graphical abstract: - Highlights: • The furan resin structure was investigated using IR and RMN techniques. • The polymerization of furan resins was developed based on multistage kinetics. • Vyazovkin numerical analysis was found the most accurate kinetic method. • Microwave curing of furan resins was much faster than thermal curing. - Abstract: The challenge of this work is the microwave curing study of low free-furfuryl alcohol content furan resins. The chemical characterization of the furan resins has been made by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The chemical composition of the resin and its reactions with p-toluensulfonic acid are proposed, with the aim of understanding the mechanism responsible for the main reactions. The results show the presence of methyl and ether bridges between the furan rings, and the formation of ketone and conjugated structures. Furthermore, the curing kinetics of the furan resins has been characterized by differential scanning calorimetry. Different methods have been applied in order to obtain and compare the activation energy of the process. Vyazovkin numerical analysis was found the most accurate method. Finally, microwave and conventional curing processes has been compared. The analysis showed that microwave curing of furan resins was twice faster than thermal curing

Polymerization and curing kinetics of furan resins under conventional and microwave heating

Energy Technology Data Exchange (ETDEWEB)

Lopez de Vergara, Unai, E-mail: bergara@gaiker.es [Plastics and Composites Department, Gaiker IK4 Research Centre, Parque Tecnológico, Ed. 202, 48170 Zamudio Spain (Spain); Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain); Sarrionandia, Mariasun [Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain); Gondra, Koldo [Plastics and Composites Department, Gaiker IK4 Research Centre, Parque Tecnológico, Ed. 202, 48170 Zamudio Spain (Spain); Aurrekoetxea, Jon [Mechanical Engineering and Industrial Manufacturing Department, Mondragón Unibertsitatea, Loramendi 4, 20500 Mondragón Spain (Spain)

2014-04-01

Graphical abstract: - Highlights: • The furan resin structure was investigated using IR and RMN techniques. • The polymerization of furan resins was developed based on multistage kinetics. • Vyazovkin numerical analysis was found the most accurate kinetic method. • Microwave curing of furan resins was much faster than thermal curing. - Abstract: The challenge of this work is the microwave curing study of low free-furfuryl alcohol content furan resins. The chemical characterization of the furan resins has been made by infrared spectroscopy and nuclear magnetic resonance spectroscopy. The chemical composition of the resin and its reactions with p-toluensulfonic acid are proposed, with the aim of understanding the mechanism responsible for the main reactions. The results show the presence of methyl and ether bridges between the furan rings, and the formation of ketone and conjugated structures. Furthermore, the curing kinetics of the furan resins has been characterized by differential scanning calorimetry. Different methods have been applied in order to obtain and compare the activation energy of the process. Vyazovkin numerical analysis was found the most accurate method. Finally, microwave and conventional curing processes has been compared. The analysis showed that microwave curing of furan resins was twice faster than thermal curing.

Stark effect measurements on monomers and trimers of reconstituted light-harvesting complex II of plants

NARCIS (Netherlands)

Palacios, M.A.; Caffarri, S.; Bassi, R.; Grondelle, van R.; Amerongen, van H.

2004-01-01

The electric-field induced absorption changes (Stark effect) of reconstituted light-harvesting complex II (LHCII) in different oligomerisation states - monomers and trimers - with different xanthophyll content have been probed at 77 K. The Stark spectra of the reconstituted control samples,

Step growth of two flexible ABf monomers

DEFF Research Database (Denmark)

Cameron, Colin; Fawcett, Allan H.; Hetherington, Cecil R.

2000-01-01

A three-dimensional lattice model was used to simulate the competition between the growth of hyperbranched structures and cycle formation that occurs when flexible ABf monomers undergo step growth. The monomers in the model are mapped onto several lattice sites. The effect of functionality...

Thermodynamics of swelling of latex particles with two monomers

NARCIS (Netherlands)

Maxwell, I.A.; Kurja, J.; van Doremaele, G.H.J.; German, A.L.

1992-01-01

The partitioning of 2 monomers between the latex particle, monomer droplet, and aq. phases of an emulsion polymer latex are measured at satn. swelling of the latex particle phase (corresponding to intervals I and II of an emulsion polymn.). The monomer (Me acrylate, Bu acrylate, styrene) and polymer

Activation of PPARγ is not involved in butyrate-induced epithelial cell differentiation

International Nuclear Information System (INIS)

Ulrich, S.; Waechtershaeuser, A.; Loitsch, S.; Knethen, A. von; Bruene, B.; Stein, J.

2005-01-01

Histone deacetylase-inhibitors affect growth and differentiation of intestinal epithelial cells by inducing expression of several transcription factors, e.g. Peroxisome proliferator-activated receptor γ (PPARγ) or vitamin D receptor (VDR). While activation of VDR by butyrate mainly seems to be responsible for cellular differentiation, the activation of PPARγ in intestinal cells remains to be elucidated. The aim of this study was to determine the role of PPARγ in butyrate-induced cell growth inhibition and differentiation induction in Caco-2 cells. Treatment with PPARγ ligands ciglitazone and BADGE (bisphenol A diglycidyl) enhanced butyrate-induced cell growth inhibition in a dose- and time-dependent manner, whereas cell differentiation was unaffected after treatment with PPARγ ligands rosiglitazone and MCC-555. Experiments were further performed in dominant-negative PPARγ mutant cells leading to an increase in cell growth whereas butyrate-induced cell differentiation was again unaffected. The present study clearly demonstrated that PPARγ is involved in butyrate-induced inhibition of cell growth, but seems not to play an essential role in butyrate-induced cell differentiation

Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

1989-09-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

Characteristics of resin floc dispersion of anion and cation exchange resin in precoat filter using powdered ion exchange resin

International Nuclear Information System (INIS)

Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

1989-01-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of resin floc dispersion. The factors related to resin floc dispersion of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index in addition to the measurement of physical, chemical and electrochemical properties of powdered ion exchange resin. The effect of adsorption of iron oxide and polymer electrolyte and of ion exchange were determined. In addition, considered floc dispersion with adsorbing iron oxide, it was assumed that the amount and filling ratio of resin floc were related to summation and multiplication of surface electric charge respectively. An experimental expression was obtained for simulation of the change of specific settle volume of resin floc by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

Chemoviscosity modeling for thermosetting resins - I

Science.gov (United States)

Hou, T. H.

1984-01-01

A new analytical model for chemoviscosity variation during cure of thermosetting resins was developed. This model is derived by modifying the widely used WLF (Williams-Landel-Ferry) Theory in polymer rheology. Major assumptions involved are that the rate of reaction is diffusion controlled and is linearly inversely proportional to the viscosity of the medium over the entire cure cycle. The resultant first order nonlinear differential equation is solved numerically, and the model predictions compare favorably with experimental data of EPON 828/Agent U obtained on a Rheometrics System 4 Rheometer. The model describes chemoviscosity up to a range of six orders of magnitude under isothermal curing conditions. The extremely non-linear chemoviscosity profile for a dynamic heating cure cycle is predicted as well. The model is also shown to predict changes of glass transition temperature for the thermosetting resin during cure. The physical significance of this prediction is unclear at the present time, however, and further research is required. From the chemoviscosity simulation point of view, the technique of establishing an analytical model as described here is easily applied to any thermosetting resin. The model thus obtained is used in real-time process controls for fabricating composite materials.

Resin infusion of layered metal/composite hybrid and resulting metal/composite hybrid laminate

Science.gov (United States)

Cano, Roberto J. (Inventor); Grimsley, Brian W. (Inventor); Weiser, Erik S. (Inventor); Jensen, Brian J. (Inventor)

2009-01-01

A method of fabricating a metal/composite hybrid laminate is provided. One or more layered arrangements are stacked on a solid base to form a layered structure. Each layered arrangement is defined by a fibrous material and a perforated metal sheet. A resin in its liquid state is introduced along a portion of the layered structure while a differential pressure is applied across the laminate structure until the resin permeates the fibrous material of each layered arrangement and fills perforations in each perforated metal sheet. The resin is cured thereby yielding a metal/composite hybrid laminate.

Scanning electron microscopy evaluation of the interaction pattern between dentin and resin after cavity preparation using Er:YAG laser

International Nuclear Information System (INIS)

Schein, Marcelo Thome

2001-01-01

The aim of this study was to describe the interaction pattern formed between dentin and resin on cavities prepared with an erbium laser (Er:YAG). The morphological aspect of the irradiated dentin after acid etching was also observed. Ten dentin disks were obtained from fresh extracted third molars. Each disk received two cavities, one prepared with a conventional high-speed drill, while the other cavity was obtained by the use of an Er:YAG laser (KaVo KEY Laser, KaVo Co.). The laser treatment was performed with 250 mJ/pulse, 4 Hz, non contact mode, focused beam, and a fine water mist was used. Five disks were prepared for morphological analysis of the acid etched dentin. The other five disks had their cavities restored with Single Bond (3M) followed by Z100 resin (3M). The specimens were observed under scanning electron microscopy after dentin-resin interface demineralization and deproteinization. It was observed that the morphological characteristics of the acid-etched irradiated dentin were not favorable to the diffusion of monomers through the collagen network. The dentin resin interfacial aspect of irradiated dentin, after acid etching, showed thin tags and scarce hybridization zones, which agreed with the morphology of the irradiated and acid-etched dentin substrate observed. (author)

Green Thermosetting Factory: Novel Star-Shaped Biobased Systems and Their Thermosetting Resins; Synthesis and Characterization

Science.gov (United States)

Jahandideh, Arash

Increasing attentions toward sustainable development, economic and environmental issues have led to many attempts at replacing the petroleum-based materials with renewables. Substitution of petroleum-based platforms with green alternative technologies is beneficiary in different ways. Using bio-renewables reduces the dependency of the national plastic industry to the petroleum resources and substantially promotes the environmental profile and sustainability of the product. It is expected that the emergence of the corn-based thermosetting industry generates substantial profits for the corn production sector. Developments in the emerging biobased thermosets are spectacular from a technological point of view. However, there are still several disadvantages associated with the current biobased thermosetting resins, e.g. low processability, environmental issues, expensive sources and poor thermomechanical properties. Use of natural fibers not only contributes to the production of a more environmentally friendly product, but also has advantages such as low-weight product and low manufacturing costs. The results of this study show a possibility of production of biocomposites made from natural fibers and star-shaped resin, synthesized from corn-based materials (lactic acid and itaconic acid) and different multihydroxyl core molecules. These resins were synthesized via two-steps strategy: polycondensation of the monomers with the core molecules followed by end-functionalization of the branches by methacrylic anhydride or itaconic acid. The results have shown that these resin are capable of competing with or even surpassing fossil fuel based resins in terms of cost and eco-friendliness aspect. Inexpensive biobased raw material, better environmental profile, low viscosity, and better processability of the matrix along with better thermomechanical properties of the produced biocomposites are of advantages expected for these systems.

Tailoring surface properties of ArF resists thin films with functionally graded materials (FGM)

Science.gov (United States)

Takemoto, Ichiki; Ando, Nobuo; Edamatsu, Kunishige; Fuji, Yusuke; Kuwana, Koji; Hashimoto, Kazuhiko; Funase, Junji; Yokoyama, Hiroyuki

2007-03-01

Our recent research effort has been focused on new top coating-free 193nm immersion resists with regard to leaching of the resist components and lithographic performance. We have examined methacrylate-based resins that control the surface properties of ArF resists thin films by surface segregation behavior. For a better understanding of the surface properties of thin films, we prepared the six resins (Resin 1-6) that have three types fluorine containing monomers, a new monomer (Monomer A), Monomer B and Monomer C, respectively. We blended the base polymer (Resin 0) with Resin (1-6), respectively. We evaluated contact angles, surface properties and lithographic performances of the polymer blend resists. The static and receding contact angles of the resist that contains Resin (1-6) are greater than that of the base polymer (Resin 0) resist. The chemical composition of the surface of blend polymers was investigated with X-ray photoelectron spectroscopy (XPS). It was shown that there was significant segregation of the fluorine containing resins to the surface of the blend films. We analyzed Quantitative Structure-Property Relationships (QSPR) between the surface properties and the chemical composition of the surface of polymer blend resists. The addition of 10 wt% of the polymer (Resin 1-6) to the base polymer (Resin 0) did not influence the lithographic performance. Consequently, the surface properties of resist thin films can be tailored by the appropriate choice of fluorine containing polymer blends.

Surface coatings of unsaturated polyester resin Kamper wood (Dry obalan ops spp.) by using UV radiation

International Nuclear Information System (INIS)

Sugiarto Danu; Yusuf Sudo Hadi; Novi Eka Putri

1999-01-01

Kamper wood (Dryobalanops spp.) has high contribution in wood working industry and most of them need surface coating process. Radiation curing of surface coating, especially the use of ultra-violet (UV) light have potential to give contribution in the wood finishing. The experiment on surface coating of kamper wood has been conducted by using UV-radiation. Unsaturated polyester resin with the commercial name of Yucalac type 157 was used as coating materials after being added with styrene monomer, some fillers and radical photoinitiator of 2-hydroxy-2-2-methyl-l- phenyl propanone. Four photoinitiator concentration levels of 1.5 ; 2 ; 2.5 and 3 % by weight of resin were used. The coating materials were coated onto the wood panel samples by using high pressure sprayer. The wood samples were then exposed to irradiation by using 80 Watts/cm UV-source with variable conveyor speed of 3 ; 4 ; 5 and 5.8 m/min. Formulation of coating materials, pendulum hardness, adhesion, and gloss of cured films were evaluated

Resin Viscosity Influence on Fiber Compaction in Tapered Resin Injection Pultrusion Manufacturing

Science.gov (United States)

Masuram, N. B.; Roux, J. A.; Jeswani, A. L.

2018-06-01

Viscosity of the liquid resin effects the chemical and mechanical properties of the pultruded composite. In resin injection pultrusion manufacturing the liquid resin is injected into a specially designed tapered injection chamber through the injection slots present on top and bottom of the chamber. The resin is injected at a pressure so as to completely wetout the fiber reinforcements inside the tapered injection chamber. As the resin penetrates through the fibers, the resin also pushes the fibers away from the wall towards the center of chamber causing compaction of the fiber reinforcements. The fibers are squeezed together due to compaction, making resin penetration more difficult; thus higher resin injection pressures are required to efficaciously penetrate through the compacted fibers and achieve complete wetout. The impact of resin viscosity on resin flow, fiber compaction, wetout and on the final product is further discussed. Injection chamber design predominantly effects the resin flow inside the chamber and the minimum injection pressure required to completely wet the fibers. Therefore, a desirable injection chamber design is such that wetout occurs at lower injection pressures and at low internal pressures inside the injection chamber.

High-flexibility combinatorial peptide synthesis with laser-based transfer of monomers in solid matrix material.

Science.gov (United States)

Loeffler, Felix F; Foertsch, Tobias C; Popov, Roman; Mattes, Daniela S; Schlageter, Martin; Sedlmayr, Martyna; Ridder, Barbara; Dang, Florian-Xuan; von Bojničić-Kninski, Clemens; Weber, Laura K; Fischer, Andrea; Greifenstein, Juliane; Bykovskaya, Valentina; Buliev, Ivan; Bischoff, F Ralf; Hahn, Lothar; Meier, Michael A R; Bräse, Stefan; Powell, Annie K; Balaban, Teodor Silviu; Breitling, Frank; Nesterov-Mueller, Alexander

2016-06-14

Laser writing is used to structure surfaces in many different ways in materials and life sciences. However, combinatorial patterning applications are still limited. Here we present a method for cost-efficient combinatorial synthesis of very-high-density peptide arrays with natural and synthetic monomers. A laser automatically transfers nanometre-thin solid material spots from different donor slides to an acceptor. Each donor bears a thin polymer film, embedding one type of monomer. Coupling occurs in a separate heating step, where the matrix becomes viscous and building blocks diffuse and couple to the acceptor surface. Furthermore, we can consecutively deposit two material layers of activation reagents and amino acids. Subsequent heat-induced mixing facilitates an in situ activation and coupling of the monomers. This allows us to incorporate building blocks with click chemistry compatibility or a large variety of commercially available non-activated, for example, posttranslationally modified building blocks into the array's peptides with >17,000 spots per cm(2).

[Influences of composition on brush wear of composite resins. Influences of particle size and content of filler].

Science.gov (United States)

Yuasa, S

1990-07-01

The influences of the composition on abrasion resistance of composite resins were examined using various experimental composite resins which had various matrix resin, filler size and content. The abrasion test was conducted by the experimental toothbrush abrasion testing machine developed in our laboratory. Three series of heat-curing composite resins were tested. One series was made from a Bis-MPEPP or UDMA monomer, and a silica filler with an average particle size of 0.04, 1.9, 3.8, 4.3, 7.5, 13.8 and 14.1 microns. The filler content of this series was constant at 45 wt%. The second series contained a silica filler of 4.3 microns in a content ranging from 35 to 75 wt%. The third series contained a microfiller (0.04 microns) and macrofiller (4.3 microns) in total content of 45 wt%. In this series, the microfiller was gradually replaced by 5, 15, 25 and 45 wt% of the macrofiller. The results obtained for these three series indicated that the abrasion resistance of composite resins was controlled by the inorganic filler, mainly filler size and content. The abrasion loss did not vary with the difference of matrix resin. When the particle size of the filler was below about 5 microns, the abrasion resistance decreased markedly with the decrease in filler size. The composite resin which contained a 0.04 or 1.9 micron filler was less resistant to toothbrush wear than the unfilled matrix resin. However, the microfiller also contributed to abrasion resistance when used in combination with the macrofiller, although abrasion resistance decreased with the increase in the microfiller concentration. The increase of filler content clearly improved the abrasion resistance when used the macrofiller. The analysis of these results and SEM observations of the brushed surfaces of samples suggested that the toothbrush abrasion was three-body abrasion caused by the abrasive in the toothpaste, and affected by the difference in the particle size between abrasive and filler, and between

Effects of blood contamination on resin-resin bond strength.

Science.gov (United States)

Eiriksson, Sigurdur O; Pereira, Patricia N R; Swift, Edward J; Heymann, Harald O; Sigurdsson, Asgeir

2004-02-01

Incremental placement and curing of resin composites has been recommended. However, this requires longer operating time, and therefore, increased risk of contamination. The purpose of this study was to evaluate the effects of blood contamination on microtensile bond strengths (microTBS) between resin interfaces and to determine the best decontamination method to re-establish the original resin-resin bond strength. The top surfaces of 64, 4-mm composite blocks (Z-250, Renew, APX, Pertac II) were untreated as the control, or were treated as follows: blood applied and dried on the surface (Treatment 1), blood applied, rinsed, dried (Treatment 2), blood applied, rinsed, and an adhesive applied (Single Bond, One-Step, Clearfil SE, Prompt L-Pop) (Treatment 3). Fresh composite was applied and light-cured in 2-mm increments. After 24 h storage in water, the specimens were sectioned into 0.7-mm thick slabs, trimmed to a cross-sectional area of 1 mm(2), and loaded to failure at a crosshead speed of 1 mm/min using an Instron universal testing machine. Data were analyzed using two-way ANOVA and Fisher's PLSD test (pcontamination resulted in resin-resin bond strengths of only 1.0-13.1 MPa. Rinsing raised bond strengths to over 40 MPa for each material. Use of an adhesive further increased bond strengths except for Pertac II. Rinsing blood from contaminated surfaces increases the resin-resin bond strength significantly and the application of an appropriate adhesive increases the bond strength to control levels.

Dimer monomer transition and dimer re-formation play important role for ATM cellular function during DNA repair

International Nuclear Information System (INIS)

Du, Fengxia; Zhang, Minjie; Li, Xiaohua; Yang, Caiyun; Meng, Hao; Wang, Dong; Chang, Shuang; Xu, Ye; Price, Brendan; Sun, Yingli

2014-01-01

Highlights: • ATM phosphorylates the opposite strand of the dimer in response to DNA damage. • The PETPVFRLT box of ATM plays a key role in its dimer dissociation in DNA repair. • The dephosphorylation of ATM is critical for dimer re-formation after DNA repair. - Abstract: The ATM protein kinase, is a serine/threonine protein kinase that is recruited and activated by DNA double-strand breaks, mediates responses to ionizing radiation in mammalian cells. Here we show that ATM is held inactive in unirradiated cells as a dimer and phosphorylates the opposite strand of the dimer in response to DNA damage. Cellular irradiation induces rapid intermolecular autophosphorylation of serine 1981 that causes dimer dissociation and initiates cellular ATM kinase activity. ATM cannot phosphorylate the substrates when it could not undergo dimer monomer transition. After DNA repair, the active monomer will undergo dephosphorylation to form dimer again and dephosphorylation is critical for dimer re-formation. Our work reveals novel function of ATM dimer monomer transition and explains why ATM dimer monomer transition plays such important role for ATM cellular activity during DNA repair

HIF-1α as a Regulator of BMP2-Induced Chondrogenic Differentiation, Osteogenic Differentiation, and Endochondral Ossification in Stem Cells

Directory of Open Access Journals (Sweden)

Nian Zhou

2015-04-01

Full Text Available Background/Aims: Joint cartilage defects are difficult to treat due to the limited self-repair capacities of cartilage. Cartilage tissue engineering based on stem cells and gene enhancement is a potential alternative for cartilage repair. Bone morphogenetic protein 2 (BMP2 has been shown to induce chondrogenic differentiation in mesenchymal stem cells (MSCs; however, maintaining the phenotypes of MSCs during cartilage repair since differentiation occurs along the endochondral ossification pathway. In this study, hypoxia inducible factor, or (HIF-1α, was determined to be a regulator of BMP2-induced chondrogenic differentiation, osteogenic differentiation, and endochondral bone formation. Methods: BMP2 was used to induce chondrogenic and osteogenic differentiation in stem cells and fetal limb development. After HIF-1α was added to the inducing system, any changes in the differentiation markers were assessed. Results: HIF-1α was found to potentiate BMP2-induced Sox9 and the expression of chondrogenesis by downstream markers, and inhibit Runx2 and the expression of osteogenesis by downstream markers in vitro. In subcutaneous stem cell implantation studies, HIF-1α was shown to potentiate BMP2-induced cartilage formation and inhibit endochondral ossification during ectopic bone/cartilage formation. In the fetal limb culture, HIF-1α and BMP2 synergistically promoted the expansion of the proliferating chondrocyte zone and inhibited chondrocyte hypertrophy and endochondral ossification. Conclusion: The results of this study indicated that, when combined with BMP2, HIF-1α induced MSC differentiation could become a new method of maintaining cartilage phenotypes during cartilage tissue engineering.

Synthesis and Mechanism of Metal-Mediated Polymerization of Phenolic Resins

Directory of Open Access Journals (Sweden)

Zhao Yi

2016-04-01

Full Text Available Phenol-formaldehyde (PF resin is a high performance adhesive, but has not been widely developed due to its slow curing rate and high curing temperature. To accelerate the curing rate and to lower the curing temperature of PF resin, four types of metal-mediated catalysts were employed in the synthesis of PF resin; namely, barium hydroxide (Ba(OH2, sodium carbonate (Na2CO3, lithium hydroxide (LiOH, and zinc acetate ((CH3COO2Zn. The cure-acceleration effects of these catalysts on the properties of PF resins were measured, and the chemical structures of the PF resins accelerated with the catalysts were investigated by using Fourier transform infrared (FT-IR spectroscopy and quantitative liquid carbon-13 nuclear magnetic resonance (13C NMR. The results showed that the accelerated efficiency of these catalysts to PF resin could be ordered in the following sequence: Na2CO3 > (CH3COO2Zn > Ba(OH2 > LiOH. The catalysts (CH3COO2Zn and Na2CO3 increased the reaction activity of the phenol ortho position and the condensation reaction of ortho methylol. The accelerating mechanism of (CH3COO2Zn on PF resin is probably different from that of Na2CO3, which can be confirmed by the differences in the differential thermogravimetric (DTG curve and thermogravimetric (TG data. Compared to the Na2CO3-accelerated PF resin, the (CH3COO2Zn-accelerated PF resin showed different peaks in the DTG curve and higher weight residues. In the synthesis process, the catalyst (CH3COO2Zn may form chelating compounds (containing a metal-ligand bond, which can promote the linkage of formaldehyde to the phenolic hydroxyl ortho position.

Foam, Foam-resin composite and method of making a foam-resin composite

Science.gov (United States)

Cranston, John A. (Inventor); MacArthur, Doug E. (Inventor)

1995-01-01

This invention relates to a foam, a foam-resin composite and a method of making foam-resin composites. The foam set forth in this invention comprises a urethane modified polyisocyanurate derived from an aromatic amino polyol and a polyether polyol. In addition to the polyisocyanurate foam, the composite of this invention further contains a resin layer, wherein the resin may be epoxy, bismaleimide, or phenolic resin. Such resins generally require cure or post-cure temperatures of at least 350.degree. F.

Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials.

Science.gov (United States)

Cui, Yong; Hou, Xiaopeng; Wang, Wenliang; Chang, Jianmin

2017-06-18

In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF) resin-a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

Influence of CuO nanoparticle on palm oil based alkyd resin preparation and its antimicrobial activity

Science.gov (United States)

Ruey Ong, Huei; Maksudur Rahman Khan, Md.; Ramli, Ridzuan; Shein Hong, Chi; Yunus, Rosli Mohd

2018-03-01

An alkyd resin has been synthesized from palm oil that reacted with glycerol and phthalic anhydride by alcoholysis-polyesterification process and co-catalyzed by CuO nanoparticle. The CuO nanoparticle was pre-prepared in the glycerol via sol gel method, which creates a new reaction condition for resin preparation. The resins were characterized by fourier transform infrared spectroscopy (FTIR), where a new ester linkage bond (C-O-C) was noticed for resin sample. The antimicrobial activity and the curing behaviour of the resin were determined by Kirby-Bauer and differential scanning calorimeter technique. It was found that, the addition of CuO speeded up the reaction rate and played antimicrobial role. Moreover, it shortens the reaction time of alcoholysis and polyesterification process.

In-vitro transdentinal diffusion of monomers from adhesives.

Science.gov (United States)

Putzeys, Eveline; Duca, Radu Corneliu; Coppens, Lieve; Vanoirbeek, Jeroen; Godderis, Lode; Van Meerbeek, Bart; Van Landuyt, Kirsten L

2018-06-01

Biocompatibility of adhesives is important since adhesives may be applied on dentin near the pulp. Accurate knowledge of the quantity of monomers reaching the pulp is important to determine potential side effects. The aim of this study was to assess the transdentinal diffusion of residual monomers from dental adhesive systems using an in-vitro pulp chamber model. Dentin disks with a thickness of 300 µm were produced from human third molars. These disks were fixed between two open-ended glass tubes, representing an in-vitro pulp chamber. The etch-and-rinse adhesive OptiBond FL and the self-etch adhesive Clearfil SE Bond were applied to the dentin side of the disks, while on in the pulpal side, the glass tube was filled with 600 µL water. The transdentinal diffusion of different monomers was quantified using ultra-performance liquid chromatography-tandem mass spectrometry. The monomers HEMA, CQ, BisGMA, GPDM, 10-MDP and UDMA eluted from the dental materials and were able to diffuse through the dentin disks to a certain extent. Compounds with a lower molecular weight (uncured group: HEMA 7850 nmol and CQ 78.2 nmol) were more likely to elute and diffuse compared to monomers with a higher molecular weight (uncured group: BisGMA 0.42 nmol). When the adhesives were left uncured, diffusion was up to 10 times higher compared to the cured conditions. This in-vitro research resulted in the quantification of various monomers able to diffuse through dentin and therefore contributes to a more detailed understanding about the potential exposure of the dental pulp to monomers from dental adhesives. Biocompatibility of adhesives is important since adhesives may be applied on dentin near the pulp, where tubular density and diameter are greatest. Copyright © 2018. Published by Elsevier Ltd.

The effect of monomer molecular weight on grafting reaction

International Nuclear Information System (INIS)

Wu Minghong; Ding Zhongli; Ma Zueteh

1995-01-01

In this paper, some condensed ethylene glycol acrylate monomers with different molecular weight being grafted to the PE film by means of pre-irradiation is reported. The effect of molecular weight of monomer on grafting reaction and the hydrophilicity of grafting sample have been discussed. The experimental results show: molar degrees of grafting decreased non-linearly with the increasement of molecular weight of monomer, the grafting reaction of polymer is greater effected by the swelling degree of PE film, the greater the swelling degree of grafting material, the higher the grating degree grafting is, the initial rate of grafting reaction decreased with the increasement of molecular weight of monomer. (author)

Inactivation of EGFR/AKT signaling enhances TSA-induced ovarian cancer cell differentiation.

Science.gov (United States)

Shao, Genbao; Lai, Wensheng; Wan, Xiaolei; Xue, Jing; Wei, Ye; Jin, Jie; Zhang, Liuping; Lin, Qiong; Shao, Qixiang; Zou, Shengqiang

2017-05-01

Ovarian tumor is one of the most lethal gynecologic cancers, but differentiation therapy for this cancer is poorly characterized. Here, we show that thrichostatin A (TSA), the well known inhibitor of histone deacetylases (HDACs), can induce cell differentiation in HO8910 ovarian cancer cells. TSA-induced cell differentiation is characterized by typical morphological change, increased expression of the differentiation marker FOXA2, decreased expression of the pluripotency markers SOX2 and OCT4, suppressing cell proliferation, and cell cycle arrest in the G1 phase. TSA also induces an elevated expression of cell cycle inhibitory protein p21Cip1 along with a decrease in cell cycle regulatory protein cyclin D1. Significantly, blockage of epidermal growth factor receptor (EGFR) signaling pathway with specific inhibitors of this signaling cascade promotes the TSA-induced differentiation of HO8910 cells. These results imply that the EGFR cascade inhibitors in combination with TSA may represent a promising differentiation therapy strategy for ovarian cancer.

Kaempferol impedes IL-32-induced monocyte-macrophage differentiation.

Science.gov (United States)

Nam, Sun-Young; Jeong, Hyun-Ja; Kim, Hyung-Min

2017-08-25

Kaempferol possesses a wide range of therapeutic properties, including antioxidant, anti-inflammatory, and anticancer properties. The present study sought to evaluate the effects and possible pharmacological mechanisms of kaempferol on interleukin (IL)-32-induced monocyte-macrophage differentiation. In this study, we performed flow cytometry assay, immunocytochemical staining, quantitative real-time PCR, enzyme-linked immuno sorbent assay, caspase-1 assay, and Western blotting to observe the effects and underlying mechanisms of kaempferol using the human monocyte cell line THP-1. The flow cytometry, immunocytochemical staining, and real-time PCR results show that kaempferol attenuated IL-32-induced monocyte differentiation to product macrophage-like cells. Kaempferol decreased the production and mRNA expression of pro-inflammatory cytokines, in this case thymic stromal lymphopoietin (TSLP), IL-1β, tumor necrosis factor (TNF)-α, and IL-8. Furthermore, kaempferol inhibited the IL-32-induced activation of p38 and nuclear factor-κB in a dose-dependent manner in THP-1 cells. Kaempferol also ameliorated the lipopolysaccharide-induced production of the inflammatory mediators TSLP, IL-1β, TNF-α, IL-8, and nitric oxide of macrophage-like cells differentiated by IL-32. In brief, our findings may provide new mechanistic insights into the anti-inflammatory effects of kaempferol. Copyright © 2017 Elsevier B.V. All rights reserved.

Synthesis of 1, 4-Dioxan-2-one from 1, 3-Dioxolane and Carbon Monoxide over Cation-exchange Resin Catalyst

OpenAIRE

Takagi, Hiroyuki; Oumi, Yasunori; Uozumi, Toshiya; Masuda, Takashi; Sano, Tsuneji

2001-01-01

The possibility of the synthesis of 1, 4-dioxan-2-one (p-dioxanon) by carbonylation of 1, 3-dioxolane (cyclic ether) over Nafion® NR-50 cation-exchange resin catalyst was investigated. 1, 4-Dioxan-2-one, one of the cyclic esterethers used as a monomer of polyester, was obtained by depolymerization of polyester oligomers. The maximum yield (40%) of 1, 4-dioxan-2-one was achieved under reaction conditions of 25MPa initial PCO, 120°C reaction temperature and 4h reaction time.

Bacterial viability and physical properties of antibacterially modified experimental dental resin composites.

Directory of Open Access Journals (Sweden)

Stefan Rüttermann

Full Text Available PURPOSE: To investigate the antibacterial effect and the effect on the material properties of a novel delivery system with Irgasan as active agent and methacrylated polymerizable Irgasan when added to experimental dental resin composites. MATERIALS AND METHODS: A delivery system based on novel polymeric hollow beads, loaded with Irgasan and methacrylated polymerizable Irgasan as active agents were used to manufacture three commonly formulated experimental resin composites. The non-modified resin was used as standard (ST. Material A contained the delivery system providing 4 % (m/m Irgasan, material B contained 4 % (m/m methacrylated Irgasan and material C 8 % (m/m methacrylated Irgasan. Flexural strength (FS, flexural modulus (FM, water sorption (WS, solubility (SL, surface roughness Ra, polymerization shrinkage, contact angle Θ, total surface free energy γS and its apolar γS (LW, polar γS (AB, Lewis acid γS (+and base γS (- term as well as bacterial viability were determined. Significance was p < 0.05. RESULTS: The materials A to C were not unacceptably influenced by the modifications and achieved the minimum values for FS, WS and SL as requested by EN ISO 4049 and did not differ from ST what was also found for Ra. Only A had lower FM than ST. Θ of A and C was higher and γS (AB of A and B was lower than of ST. Materials A to C had higher γS (+ than ST. The antibacterial effect of materials A to C was significantly increased when compared with ST meaning that significantly less vital cells were found. CONCLUSION: Dental resin composites with small quantities of a novel antibacterially doped delivery system or with an antibacterial monomer provided acceptable physical properties and good antibacterial effectiveness. The sorption material being part of the delivery system can be used as a vehicle for any other active agent.

Decreased Intracellular pH Induced by Cariporide Differentially Contributes to Human Umbilical Cord-Derived Mesenchymal Stem Cells Differentiation

Directory of Open Access Journals (Sweden)

Wei Gao

2014-01-01

Full Text Available Background/Aims: Na+/H+ exchanger 1 (NHE1 is an important regulator of intracellular pH (pHi. High pHi is required for cell proliferation and differentiation. Our previous study has proven that the pHi of mesenchymal stem cells is higher than that of normal differentiated cells and similar to tumor cells. NHE1 is highly expressed in both mesenchymal stem cells and tumor cells. Targeted inhibition of NHE1 could induce differentiation of K562 leukemia cells. In the present paper we explored whether inhibition of NHE1 could induce differentiation of mesenchymal stem cells. Methods: MSCs were obtained from human umbilical cord and both the surface phenotype and functional characteristics were analyzed. Selective NHE1 inhibitor cariporide was used to treat human umbilical cord-derived mesenchymal stem cells (hUC-MSCs. The pHi and the differentiation of hUC-MSCs were compared upon cariporide treatment. The putative signaling pathway involved was also explored. Results: The pHi of hUC-MSCs was decreased upon cariporide treatment. Cariporide up-regulated the osteogenic differentiation of hUC-MSCs while the adipogenic differentiation was not affected. For osteogenic differentiation, β-catenin expression was up-regulated upon cariporide treatment. Conclusion: Decreased pHi induced by cariporide differentially contributes to hUC-MSCs differentiation.

PI3K/AKT and ERK regulate retinoic acid-induced neuroblastoma cellular differentiation

Energy Technology Data Exchange (ETDEWEB)

Qiao, Jingbo [Department of Pediatric Surgery, Vanderbilt University Medical Center, Nashville, TN 37232 (United States); Paul, Pritha; Lee, Sora [Department of Pediatric Surgery, Vanderbilt University Medical Center, Nashville, TN 37232 (United States); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232 (United States); Qiao, Lan; Josifi, Erlena; Tiao, Joshua R. [Department of Pediatric Surgery, Vanderbilt University Medical Center, Nashville, TN 37232 (United States); Chung, Dai H., E-mail: dai.chung@vanderbilt.edu [Department of Pediatric Surgery, Vanderbilt University Medical Center, Nashville, TN 37232 (United States); Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, TN 37232 (United States)

2012-08-03

Highlights: Black-Right-Pointing-Pointer Retinoic acid (RA) induces neuroblastoma cells differentiation, which is accompanied by G0/G1 cell cycle arrest. Black-Right-Pointing-Pointer RA resulted in neuroblastoma cell survival and inhibition of DNA fragmentation; this is regulated by PI3K pathway. Black-Right-Pointing-Pointer RA activates PI3K and ERK1/2 pathway; PI3K pathway mediates RA-induced neuroblastoma cell differentiation. Black-Right-Pointing-Pointer Upregulation of p21 is necessary for RA-induced neuroblastoma cell differentiation. -- Abstract: Neuroblastoma, the most common extra-cranial solid tumor in infants and children, is characterized by a high rate of spontaneous remissions in infancy. Retinoic acid (RA) has been known to induce neuroblastoma differentiation; however, the molecular mechanisms and signaling pathways that are responsible for RA-mediated neuroblastoma cell differentiation remain unclear. Here, we sought to determine the cell signaling processes involved in RA-induced cellular differentiation. Upon RA administration, human neuroblastoma cell lines, SK-N-SH and BE(2)-C, demonstrated neurite extensions, which is an indicator of neuronal cell differentiation. Moreover, cell cycle arrest occurred in G1/G0 phase. The protein levels of cyclin-dependent kinase inhibitors, p21 and p27{sup Kip}, which inhibit cell proliferation by blocking cell cycle progression at G1/S phase, increased after RA treatment. Interestingly, RA promoted cell survival during the differentiation process, hence suggesting a potential mechanism for neuroblastoma resistance to RA therapy. Importantly, we found that the PI3K/AKT pathway is required for RA-induced neuroblastoma cell differentiation. Our results elucidated the molecular mechanism of RA-induced neuroblastoma cellular differentiation, which may be important for developing novel therapeutic strategy against poorly differentiated neuroblastoma.

Development of a novel resin-based dental material with dual biocidal modes and sustained release of Ag+ ions based on photocurable core-shell AgBr/cationic polymer nanocomposites.

Science.gov (United States)

Cao, Weiwei; Zhang, Yu; Wang, Xi; Chen, Yinyan; Li, Qiang; Xing, Xiaodong; Xiao, Yuhong; Peng, Xuefeng; Ye, Zhiwen

2017-07-01

Research on the incorporation of cutting-edge nano-antibacterial agent for designing dental materials with potent and long-lasting antibacterial property is demanding and provoking work. In this study, a novel resin-based dental material containing photocurable core-shell AgBr/cationic polymer nanocomposite (AgBr/BHPVP) was designed and developed. The shell of polymerizable cationic polymer not only provided non-releasing antibacterial capability for dental resins, but also had the potential to polymerize with other methacrylate monomers and prevented nanoparticles from aggregating in the resin matrix. As a result, incorporation of AgBr/BHPVP nanocomposites did not adversely affect the flexural strength and modulus but greatly increased the Vicker's hardness of resin disks. By continuing to release Ag + ions without the impact of anaerobic environment, resins containing AgBr/BHPVP nanoparticles are particularly suitable to combat anaerobic cariogenic bacteria. By reason of the combined bactericidal effect of the contact-killing cationic polymers and the releasing-killing Ag + ions, AgBr/BHPVP-containing resin disks had potent bactericidal activity against S. mutans. The long-lasting antibacterial activity was also achieved through the sustained release of Ag + ions due to the core-shell structure of the nanocomposites. The results of macrophage cytotoxicity showed that the cell viability of dental resins loading less than 1.0 wt% AgBr/BHPVP was close to that of neat resins. The AgBr/BHPVP-containing dental resin with dual bactericidal capability and long term antimicrobial effect is a promising material aimed at preventing second caries and prolonging the longevity of resin composite restorations.

Old resinous turpentine stumps as an indicator of the range of longleaf pine in Southeastern Virginia

Science.gov (United States)

Thomas L. Eberhardt; Philip M. Sheridan; Jolie M. Mahfouz; Chi-Leung So

2006-01-01

Wood anatomy cannot be used to differentiate between the southern yellow pine species. Wood samples collected from old resinous turpentine stumps in coastal Virginia were subjected to chemical and spectroscopic analyses in an effort to determine if they could be identified as longleaf pine. The age and resinous nature of the samples were manifested in high specific...

Dynamic conformations of nucleophosmin (NPM1 at a key monomer-monomer interface affect oligomer stability and interactions with granzyme B.

Directory of Open Access Journals (Sweden)

Wei D Duan-Porter

Full Text Available Nucleophosmin (NPM1 is an abundant, nucleolar tumor antigen with important roles in cell proliferation and putative contributions to oncogenesis. Wild-type NPM1 forms pentameric oligomers through interactions at the amino-terminal core domain. A truncated form of NPM1 found in some hepatocellular carcinoma tissue formed an unusually stable oligomer and showed increased susceptibility to cleavage by granzyme B. Initiation of translation at the seventh methionine generated a protein (M7-NPM that shared all these properties. We used deuterium exchange mass spectrometry (DXMS to perform a detailed structural analysis of wild-type NPM1 and M7-NPM, and found dynamic conformational shifts or local "unfolding" at a specific monomer-monomer interface which included the β-hairpin "latch." We tested the importance of interactions at the β-hairpin "latch" by replacing a conserved tyrosine in the middle of the β-hairpin loop with glutamic acid, generating Y67E-NPM. Y67E-NPM did not form stable oligomers and further, prevented wild-type NPM1 oligomerization in a dominant-negative fashion, supporting the critical role of the β-hairpin "latch" in monomer-monomer interactions. Also, we show preferential cleavage by granzyme B at one of two available aspartates (either D161 or D122 in M7-NPM and Y67E-NPM, whereas wild-type NPM1 was cleaved at both sites. Thus, we observed a correlation between the propensity to form oligomers and granzyme B cleavage site selection in nucleophosmin proteins, suggesting that a small change at an important monomer-monomer interface can affect conformational shifts and impact protein-protein interactions.

X-radiation-induced differentiation of xenotransplanted human undifferentiated rhabdomyosarcoma

International Nuclear Information System (INIS)

Takizawa, T.; Matsui, T.; Maeda, Y.

1989-01-01

A serially xenotransplantable strain of undifferentiated embryonal rhabdomyosarcoma originating from the nasal cavity of a 42-year-old woman has been established in our laboratory. After radiotherapy for the tumor donor, distinct rhabdomyoblastic differentiation of the undifferentiated sarcoma cells appeared in the primary lesion, and it is a reasonable assumption that X-irradiation has a certain potentiality to induce morphologic differentiation of tumor cells. To study this possibility, tissue fragments of undifferentiated embryonal rhabdomyosarcoma that had grown to more than 10 mm after being transplanted to nude mice were selectively irradiated in situ. The degree of rhabdomyoblastic differentiation according to radiation dose was evaluated by light and electron microscopy and by immunostainability for myoglobin, creatine phosphokinase-MM, and desmin. Distinct morphologic differentiation of undifferentiated sarcoma cells could be induced by repeated X-irradiations at several-week intervals

Polymerization of impregnated monomer in wood by microwave irradiation

International Nuclear Information System (INIS)

Kawase, Kaoru; Hayakawa, Kiyoshi

1976-01-01

The manufacturing of a wood-plastic combination (WPC) by irradiation of microwave (2,450 and 915 +- 50 MHz) or gamma-ray was carried out. After the impregnation of dry woods (Hinoki: Chamaecyparis obtusa Endl., Buna: Acer mono Maxim., and Kaede: Fagus crenata Blume) with the mixture of the vinyl monomers and chemical reagents, the monomer in wood was polymerized by irradiation. In case of polymerization with microwave (2,450 MHz) the effect of oxygen was not recognized, but in the case of gamma-ray the rate of polymerization remarkably decreased in the presence of oxygen. The polymerization of various monomers was carried out also in the air, and the conversions of styrene, methyl-, ethyl-, n-propyl-, and n-butyl-methacrylate were 51.8 -- 89.1%, but that of vinyl acetate was lower (4.3 -- 8.2%). The conversion of monomers with irradiation of 915 MHz microwave was very low (2.6 -- 33.5%). The conversion of monomers increased when toluylene diisocyanate was added in the monomers. The percentage of extraction with hot benzene of WPC (chip) decreased by the addition of toluylene diisocyanate. It was concluded from C.H.N. analyses that the reaction took place among the wood, toluylene diisocyanate and methyl methacrylate. (auth.)

Environmental Effects on Constitutive and Inducible Resin Defences of Pinus taeda

Science.gov (United States)

Maria L. Lombardero; Matthew P. Ayres; Peter L. Lorio; Jonathan J. Ruel

2000-01-01

The ecological literature abounds with studies of environmental effects on plant antiherbivore defences. While various models have been proposed (e.g. plant stress, optimal allocation, growth-differentiation balance), each has met with mixed support. One possible explanation for the mixed results is that constitutive and induced defences are differentialiy affected by...

Synthesis and Characterization of Bio-Oil Phenol Formaldehyde Resin Used to Fabricate Phenolic Based Materials

Directory of Open Access Journals (Sweden)

Yong Cui

2017-06-01

Full Text Available In this study, bio-oil from the fast pyrolysis of renewable biomass was used as the raw material to synthesize bio-oil phenol formaldehyde (BPF resin—a desirable resin for fabricating phenolic-based material. During the synthesis process, paraformaldehyde was used to achieve the requirement of high solid content and low viscosity. The properties of BPF resins were tested. Results indicated that BPF resin with the bio-oil addition of 20% had good performance on oxygen index and bending strength, indicating that adding bio-oil could modify the fire resistance and brittleness of PF resin. The thermal curing behavior and heat resistance of BPF resins were investigated by differential scanning calorimetry (DSC and thermal gravimetric analysis (TGA. Results showed that adding bio-oil had an impact on curing characteristics and thermal degradation process of PF resin, but the influence was insignificant when the addition was relatively low. The chemical structure and surface characteristics of BPF resins were determined by Fourier transform infrared (FTIR spectroscopy and scanning electron microscopy (SEM. The analysis demonstrated that adding bio-oil in the amount of 20% was able to improve the crosslinking degree and form more hydrocarbon chains in PF resin.

Influence of template/functional monomer/cross‐linking monomer ratio on particle size and binding properties of molecularly imprinted nanoparticles

DEFF Research Database (Denmark)

Yoshimatsu, Keiichi; Yamazaki, Tomohiko; Chronakis, Ioannis S.

2012-01-01

A series of molecularly imprinted polymer nanoparticles have been synthesized employing various template/functional monomer/crosslinking monomer ratio and characterized in detail to elucidate the correlation between the synthetic conditions used and the properties (e.g., particle size and templat...... tuning of particle size and binding properties are required to fit practical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012...

Effects of various light curing methods on the leachability of uncured substances and hardness of a composite resin.

Science.gov (United States)

Moon, H-J; Lee, Y-K; Lim, B-S; Kim, C-W

2004-03-01

The purpose of this study was to evaluate the effect of the various light curing units (plasma arc, halogen and light-emitting diodes) and irradiation methods (one-step, two-step and pulse) using different light energy densities on the leachability of unreacted monomers (Bis-GMA and UDMA) and the surface hardness of a composite resin (Z250, 3M). Leachability of the specimens immersed for 7 days in ethanol was analysed by HPLC. Vicker's hardness number (VHN) was measured immediately after curing (IC) and after immersion in ethanol for 7 days. Various irradiation methods with three curing units resulted in differences in the amount of leached monomers and VHN of IC when light energy density was lower than 17.0 J cm(-2) (P = 0.05). However, regardless of curing units and irradiation methods, these results were not different when the time or light energy density increased. When similar light energy density was irradiated (15.6-17.7 J cm(-2)), the efficiency of irradiation methods was different by the following order: one-step > or = two-step > pulse. These results suggest that the amount of leached monomers and VHN were influenced by forming polymer structure in activation and initiation stages of polymerization process with different light source energies and curing times.

Bond strength of selected composite resin-cements to zirconium-oxide ceramic

Science.gov (United States)

Fons-Font, Antonio; Amigó-Borrás, Vicente; Granell-Ruiz, María; Busquets-Mataix, David; Panadero, Rubén A.; Solá-Ruiz, Maria F.

2013-01-01

Objectives: The aim of this study was to evaluate bond strengths of zirconium-oxide (zirconia) ceramic and a selection of different composite resin cements. Study Design: 130 Lava TM cylinders were fabricated. The cylinders were sandblasted with 80 µm aluminium oxide or silica coated with CoJet Sand. Silane, and bonding agent and/or Clearfil Ceramic Primer were applied. One hundred thirty composite cement cylinders, comprising two dual-polymerizing (Variolink II and Panavia F) and two autopolymerizing (Rely X and Multilink) resins were bonded to the ceramic samples. A shear test was conducted, followed by an optical microscopy study to identify the location and type of failure, an electron microscopy study (SEM and TEM) and statistical analysis using the Kruskal-Wallis test for more than two independent samples and Mann-Whitney for two independent samples. Given the large number of combinations, Bonferroni correction was applied (α=0.001). Results: Dual-polymerizing cements provided better adhesion values (11.7 MPa) than the autopolymerizing (7.47 MPa) (p-value M-Wzirconium-oxide ceramic, creating a more rough and retentive surface, thus providing an improved micromechanical interlocking between the cement and the ceramic. Key words:Shear bond strength, silica coating, surface treatment, zirconia ceramics, phosphate monomer. PMID:22926485

Development of transition metal oxide catalysts for treatment of off-gases released during pyrolysis of organic ion exchange resins

International Nuclear Information System (INIS)

Sathi Sasidharan, N.; Deshingkar, D.S.; Wattal, P.K.

2005-08-01

The spent IX resin wastes arising from nuclear power plants have high radiation level due to fission product 137 Cesium and activation product 60 Cobalt. The pyrolysis and oxidative pyrolysis processes have potential to minimize final waste form volumes of these wastes. The major difficulty in deploying these processes for treatment of spent IX resins is release of off-gases containing large quantities of aromatic hydrocarbons, amines, sulphur dioxide, hydrogen sulphide, carbonyl sulphide etc. As an alternative to high temperature incineration of the pyrolysis off gases, feasibility of using catalytic combustion at moderate temperatures was investigated in the laboratory. Copper chromite, copper oxide-ceric oxide and vanadium pentaoxide catalysts supported on alumina were prepared and tested for oxidation of styrene monomer, toluene, ethyl benzene and trimethyl amine at 22500 hr -1 space velocity and temperature range of 300 to 500 degC. At temperatures over 475 degC, all three catatyst gave oxidation efficiency of over 97% for these compounds over concentration range of few tens of ppm to few thousands ppm. A composite catalyst bed of three catalysts comprising principally of copper chromite is proposed for treatment of IX resin pyrolysis off-gases. (author)

Macroautophagy-generated increase of lysosomal amyloid β-protein mediates oxidant-induced apoptosis of cultured neuroblastoma cells

DEFF Research Database (Denmark)

Zheng, Lin; Terman, Alexei; Hallbeck, Martin

2011-01-01

and accumulation of Aβ within lysosomes, induced apoptosis in differentiated SH-SY5Y neuroblastoma cells. Cells under hyperoxia showed: (1) increased numbers of autophagic vacuoles that contained amyloid precursor protein (APP) as well as Aβ monomers and oligomers, (2) increased reactive oxygen species production...... and resulting lysosomal Aβ accumulation are essential for oxidant-induced apoptosis in cultured neuroblastoma cells and provide additional support for the interactive role of oxidative stress and the lysosomal system in AD-related neurodegeneration....

Properties of Eco-friendly Acrylic Resin/Clay Nanocomposites Prepared by Non-aqueous Dispersion (NAD) Polymerization

Energy Technology Data Exchange (ETDEWEB)

Kim, Yeongho; Lee, Minho; Jeon, Hyeon Yeol; Min, Byong Hun; Kim, Jeong Ho [Univ. of Suwon, Hwaseong (Korea, Republic of); Lee, Young Chul [Korea Institute of Industrial Technology, Seoul (Korea, Republic of)

2016-02-15

Eco-friendly acrylic resin/clay nanocomposites containing pristine montmorillonite (PM) or modified clays (30B and 25A) were prepared from acrylic and styrenic monomers using non-aqueous dispersion (NAD) polymerization. Effect of nanoclays on physical properties of polymerization product and resulting nanocomposites was investigated. In view of NAD particle stability, addition of nanoclay at the beginning of polymerization is proved to be good. Results of gel fraction, acid value and viscosity of the NAD product showed that nanocomposites containing clay 25A showed better physical properties than the ones with other clays. GPC results exhibit the increase in molecular weight and decrease in polydispersity index for the 25A nanocomposite. Increase in layer distance confirmed from XRD analysis showed good dispersion of 25A in the nanocomposite. Thermal and dynamic mechanical analysis showed that highest glass transition temperature and storage modulus for 25A nanocomposites. These results indicate that 25A nanoclay gives the best properties in the process of non-aqueous dispersion polymerization of acrylic resin/nanoclay nanocomposites.

Properties of Eco-friendly Acrylic Resin/Clay Nanocomposites Prepared by Non-aqueous Dispersion (NAD) Polymerization

International Nuclear Information System (INIS)

Kim, Yeongho; Lee, Minho; Jeon, Hyeon Yeol; Min, Byong Hun; Kim, Jeong Ho; Lee, Young Chul

2016-01-01

Eco-friendly acrylic resin/clay nanocomposites containing pristine montmorillonite (PM) or modified clays (30B and 25A) were prepared from acrylic and styrenic monomers using non-aqueous dispersion (NAD) polymerization. Effect of nanoclays on physical properties of polymerization product and resulting nanocomposites was investigated. In view of NAD particle stability, addition of nanoclay at the beginning of polymerization is proved to be good. Results of gel fraction, acid value and viscosity of the NAD product showed that nanocomposites containing clay 25A showed better physical properties than the ones with other clays. GPC results exhibit the increase in molecular weight and decrease in polydispersity index for the 25A nanocomposite. Increase in layer distance confirmed from XRD analysis showed good dispersion of 25A in the nanocomposite. Thermal and dynamic mechanical analysis showed that highest glass transition temperature and storage modulus for 25A nanocomposites. These results indicate that 25A nanoclay gives the best properties in the process of non-aqueous dispersion polymerization of acrylic resin/nanoclay nanocomposites

Partial swelling of latex particles by two monomers

NARCIS (Netherlands)

Noel, E.F.J.; Maxwell, I.A.; German, A.L.

1993-01-01

The swelling of polymeric latex particles with solvent and monomer is of great importance for the emulsion polymn. process in regard to compn. drift and rate of polymn. For the monomer combination, Me acrylate-vinyl acetate, both satn. and partial swelling were detd. exptl. Theories for satn.

HL-60 differentiating activity and flavonoid content of the readily extractable fraction prepared from citrus juices.

Science.gov (United States)

Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M

1999-01-01

Citrus plants are rich sources of various bioactive flavonoids. To eliminate masking effects caused by hesperidin, naringin, and neoeriocitrin, the abundant flavonoid glycosides which make up 90% of the conventionally prepared sample, the readily extractable fraction from Citrus juice was prepared by adsorbing on HP-20 resin and eluting with EtOH and acetone from the resin and was subjected to HL-60 differentiation assay and quantitative analysis of major flavonoids. Screening of 34 Citrus juices indicated that King (C. nobilis) had a potent activity for inducing differentiation of HL-60, and the active principles were isolated and identified as four polymethoxylated flavonoids, namely, nobiletin, 3,3',4',5,6,7, 8-heptamethoxyflavone, natsudaidain, and tangeretin. HPLC analysis of the readily extractable fraction also indicated that King contained high amounts of these polymethoxylated flavonoids among the Citrus juices examined. Principal component and cluster analyses of the readily extractable flavonoids indicated peculiarities of King and Bergamot.

Optical emission behavior and radiation resistance of epoxy resins

International Nuclear Information System (INIS)

Kawanishi, Shunichi; Udagawa, Akira; Hagiwara, Miyuki

1987-11-01

To make clear a mechanism of radiation resistance of epoxy resin systems, a role of energy trapping site induced in bisphenol A type epoxy resins cured with 4 kinds of aromatic amines (Φ N ) was studied in comparison with the case of aliphatic amine curing system through a measurement of optical emission. In the system of the epoxy resin cured with DETA, the optical emission from an excited state of bisphenol A unit of epoxy resin and a charge transfer complex was observed. On the other hand, the optical emission from Φ N was observed in the aromatic amine curing system. Their excitation spectrum consists of peaks of absorption spectrum of BA and those of Φ N , showing that the excited state of Φ N is formed through the excitation of both BA and Φ N . Therefore, the excited energy of BA transfers to the excited state of Φ N . Emission intensity of Φ N band was 20 ∼ 100 times as large as that of BA. These results indicate that the radiation energy is effectively released as an optical emission from excited state of Φ N in the epoxy resin when cured with aromatic amine. It can be concluded from the above results that aromatic amine hardeners contribute to enhancement of the radiation resistance of epoxy resin by acting as an energy transfer agent. (author)

Epoxy resins used to seal brachytherapy seed

International Nuclear Information System (INIS)

Ferreira, Natalia Carolina Camargos; Ferraz, Wilmar Barbosa; Reis, Sergio Carneiro dos; Santos, Ana Maria Matildes dos

2013-01-01

Prostate cancer treatment with brachytherapy is recommended for patients with cancer at an early stage. In this treatment, small radioactive seeds are implanted directly in the prostate gland. These seeds are composed at least of one radionuclide carrier and an X-ray marker enclosed within a metallic tube usually sealed by laser process. This process is expensive and, furthermore, it can provoke a partial volatilization of the radionuclide and change the isotropy in dose distribution around the seed. In this paper, we present a new sealing process using epoxy resin. Three kinds of resins were utilized and characterized by scanning electron microscopy (SEM), energy dispersive X ray (EDS) and by differential scanning calorimetry (DSC) after immersion in simulated body fluid (SBF) and in sodium iodine solution (NaI). The sealing process showed excellent potential to replace the sealing laser usually employed. (author)

Radiation-Induced Differentiation in Human Lung Fibroblast

International Nuclear Information System (INIS)

Park, Sa-Rah; Ahn, Ji-Yeon; Han, Young-Soo; Shim, Jie-Young; Yun, Yeon-Sook; Song, Jie-Young

2007-01-01

One of the most common tumors in many countries is lung cancer and patients with lung cancer may take radiotherapy. Although radiotherapy may have its own advantages, it can also induce serious problems such as acute radiation pneumonitis and pulmonary fibrosis. Pulmonary fibrosis is characterized by excessive production of α-SMA and accumulation of extracellular matrix (ECM) such as collagen and fibronectin. There has been a great amount of research about fibrosis but the exact mechanism causing the reaction is not elucidated especially in radiation-induced fibrosis. Until now it has been known that several factors such as transforming growth factor (TGF-β), tumor necrosis factor (TNF), interleukin (IL)-1, IL-6, platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF) are related to fibrosis. Among them TGF-β with Smad signaling is known to be the main stream and other signaling molecules such as MAPK, ERK and JNK (3) also participates in the process. In addition to those above factors, it is thought that more diverse and complicate mechanisms may involve in the radiationinduced fibrosis. Therefore, to investigate the underlying mechanisms in radiation induced fibrosis, first of all, we confirmed whether radiation induces trans differentiation in human normal lung fibroblasts. Here, we suggest that not only TGF-β but also radiation can induce trans differentiation in human lung fibroblast WI-38 and IMR-90

Preparation and properties of calcium-silicate filled resins for dental restoration. Part I: chemical-physical characterization and apatite-forming ability.

Science.gov (United States)

Profeta, Andrea Corrado

2014-11-01

The aim of this study was to measure dimensional changes due to hygroscopic expansion and the bioactivity of two experimental methacrylate-based dental adhesives either incorporating Bioglass 45S5 (3-E&RA/BG) or MTA (3-E&RA/WMTA). 3-E&RA/BG, 3-E&RA/WMTA and a control filler-free resin blend (3-E&RA) were formulated from commercially available monomers. Water sorption (WS) and solubility (SL) behaviour were evaluated by weighing material disks at noted intervals; the relationship between degree of hydration and the glass transition temperature (Tg) was investigated by using differential scanning calorimetry (DSC). In vitro apatite-forming ability as a function of soaking time in phosphate-containing solutions was also determined. Kruskal-Wallis analysis of variance (ANOVA) was used to evaluate differences between groups for maximum WS, SL, net water uptake and the percentage change in Tg values. Post-ANOVA pair-wise comparisons were conducted using Mann-Whitney-U tests. 3-E&RA/BG and 3-E&RA/WMTA exhibited values of maximum WS and net water uptake that were significantly higher when compared to 3-E&RA. However, no statistically significant differences were observed in terms of SL between all the adhesives. The addition of the Bioglass 45S5 and MTA to the 3-E&RA showed no reduction of the Tg after 60 days of storage in deionized water. ATR Fourier Transform Infrared Spectroscopy (ATR-FTIR) of the filled resin disks soaked in DPBS for 60 days showed the presence of carbonate ions in different chemical phases. Dentine bonding agents comprising calcium-silicates are not inert materials in a simulated oral environment and apatite formation may occur in the intra-oral conditions. A bioactive dental material which forms apatite on the surface would have several benefits including closure of gaps forming at the resin-dentine interface and potentially better bond strength over time (less degradation of bond).

Effect of Resin Extract from Commiphora swynnertonii

African Journals Online (AJOL)

Dr Olaleye

of Commiphora swynnertonii resin on biochemical parameters in rats was investigated. Sixty rats were ... significantly elevated protein and albumin levels but had no significant effect on bilirubin and all the liver enzymes in the rats. These findings are ... hypoglycemic and hypolipidemic effects against high fat diet- induced ...

Characteristics of low polymerization shrinkage flowable resin composites in newly-developed cavity base materials for bulk filling technique.

Science.gov (United States)

Nitta, Keiko; Nomoto, Rie; Tsubota, Yuji; Tsuchikawa, Masuji; Hayakawa, Tohru

2017-11-29

The purpose of this study was to evaluate polymerization shrinkage and other physical properties of newly-developed cavity base materials for bulk filling technique, with the brand name BULK BASE (BBS). Polymerization shrinkage was measured according to ISO/FDIS 17304. BBS showed the significantly lowest polymerization shrinkage and significantly higher depth of cure than conventional flowable resin composites (p<0.05). The Knoop hardness, flexural strength and elastic modulus of that were significantly lower than conventional flowable resin composites (p<0.05). BBS had the significantly greatest filler content (p<0.05). SEM images of the surface showed failure of fillers. The lowest polymerization shrinkage was due to the incorporation of a new type of low shrinkage monomer, which has urethane moieties. There were no clear correlations between inorganic filler contents and polymerization shrinkage, flexural strength and elastic modulus. In conclusion, the low polymerization shrinkage of BBS will be useful for cavity treatment in dental clinics.

Neuropharmacological screening of essential oil from oleo gum resin of Gardenia lucida Roxb.

Science.gov (United States)

Shareef, Mohammad Zubair; Yellu, Narsimha Reddy; Achanta, Venkata Narsimha Appa Rao

2013-10-07

The oleo gum resin of Gardenia lucida is commonly employed in traditional medicine to treat multiple ailments, including epilepsy and mania. The essential oil isolated from it was screened for CNS activities to check if it is responsible for the claims made regarding the traditional use of the oleo gum resin. The hypnotic and anticonvulsant activity was assessed by pentobarbitone induced hypnosis and convulsant models-Maximum electroshock (MES) and Pentylene tetrazole (PTZ) respectively. Effect on motor activity was evaluated using an actophotometer, rotarod and grip strength methods. The oil significantly potentiated the barbitone induced hypnosis and offered significant protection against the intensity and frequency of convulsions and mortality rate in both the convulsant models. A significant decrease in locomotion, motor impairment and loss of gripping reflex was also observed. The essential oil of the oleo gum resin of Gardenia lucida is a CNS depressant and anticonvulsant with central muscle relaxant properties. This justifies the claims made regarding the use of the oleo gum resin of Gardenia lucida in CNS disorders. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Gamma radiation effect on gas production in anion exchange resins

Energy Technology Data Exchange (ETDEWEB)

Traboulsi, A. [CEA Marcoule, DEN/DTCD/SPDE/LCFI, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); E.A. LISA – METICA, Aix Marseille Université, Pôle de l’Etoile, case 451, 13397 Marseille Cedex 20 (France); Labed, V., E-mail: veronique.labed@cea.fr [CEA Marcoule, DEN/DTCD/SPDE/LCFI, BP 17171, 30207 Bagnols-sur-Cèze Cedex (France); Dauvois, V. [CEA Saclay, DEN/DANS/DPC/SECR/LSRM, 91191 Gif sur Yvette Cedex (France); Dupuy, N.; Rebufa, C. [E.A. LISA – METICA, Aix Marseille Université, Pôle de l’Etoile, case 451, 13397 Marseille Cedex 20 (France)

2013-10-01

Radiation-induced decomposition of Amberlite IRA400 anion exchange resin in hydroxide form by gamma radiolysis has been studied at various doses in different atmospheres (anaerobic, anaerobic with liquid water, and aerobic). The effect of these parameters on the degradation of ion exchange resins is rarely investigated in the literature. We focused on the radiolysis gases produced by resin degradation. When the resin was irradiated under anaerobic conditions with liquid water, the liquid phase over the resin was also analyzed to identify any possible water-soluble products released by degradation of the resin. The main products released are trimethylamine (TMA), molecular hydrogen (H{sub 2g}) and carbon dioxide (CO{sub 2g}). TMA and H{sub 2g} are produced in all the irradiation atmospheres. However, TMA was in gaseous form under anaerobic and aerobic conditions and in aqueous form in presence of liquid water. In the latter conditions, TMA{sub aq} was associated with aqueous dimethylamine (DMA{sub aq}), monomethylamine (MMA{sub aq}) and ammonia (NH{sub 4}{sup +}{sub aq}). CO{sub 2g} is formed in the presence of oxygen due to oxidation of organic compounds present in the system, in particular the degradation products such as TMA{sub g}.

The effects of alkyd/melamine resin ratio and curing temperature on the properties of the coatings

Directory of Open Access Journals (Sweden)

RADMILA Z. RADICEVIC

2005-04-01

Full Text Available Synthetic resins are used as binders in protective coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of a coating called “baking enamel” cured through functional groups of resins. The effects of the alkyd/butylated melamine resin ratio (from 85/15 to 70/30 and curing temperature (from 100°C to 160°C on the crosslinking and properties of the coating are presented in this paper. The degree of curing was determined by differential scanning calorimetry. These data were used for the estimation of the degree of crosslinking. The hardness, elasticity, impact resistance, degree of adherence and gloss were also determined. Optimal coating properties could be achieved with an alkyd/melamine resin ratio of 75/25, a curing temperature of 130 °C and a curing time of 30 min.

Prostate cancer cells induce osteoblastic differentiation via semaphorin 3A.

Science.gov (United States)

Liu, Fuzhou; Shen, Weiwei; Qiu, Hao; Hu, Xu; Zhang, Chao; Chu, Tongwei

2015-03-01

Prostate cancer metastasis to bone is the second most commonly diagnosed malignant disease among men worldwide. Such metastatic disease is characterized by the presence of osteoblastic bone lesions, and is associated with high rates of mortality. However, the various mechanisms involved in prostate cancer-induced osteoblastic differentiation have not been fully explored. Semaphorin 3A (Sema 3A) is a newly identified regulator of bone metabolism which stimulates differentiation of pre-osteoblastic cells under physiological conditions. We investigated in this study whether prostate cancer cells can mediate osteoblastic activity through Sema 3A. We cultured osteoprogenitor MC3T3-E1 cells in prostate cancer-conditioned medium, and analyzed levels of Sema 3A protein in diverse prostate cancer cell lines to identify cell lines in which Sema 3A production showed a positive correlation with osteo-stimulation. C4-2 cells were stably transfected with Sema 3A short hairpin RNA to further determine whether Sema 3A contributes to the ability of C4-2 cells to induce osteoblastic differentiation. Down-regulation of Sema 3A expression decreased indicators of C4-2 CM-induced osteoblastic differentiation, including alkaline phosphatase production and mineralization. Additionally, silencing or neutralizing Sema 3A in C4-2 cells resulted in diminished β-catenin expression in osteogenitor MC3T3-E1 cells. Our results suggest that prostate cancer-induced osteoblastic differentiation is at least partially mediated by Sema 3A, and may be regulated by the β-catenin signalling pathway. Sema 3A may represent a novel target for treatment of prostate cancer-induced osteoblastic lesions. © 2014 Wiley Periodicals, Inc.

Irradiation effects in the storage and disposal of radioactive ion-exchange resins

International Nuclear Information System (INIS)

Swyler, K.J.; Dodge, C.E.; Dayal, R.; Weiss, A.J.

1982-01-01

Research is under way to characterize the effects of self-irradiation on radwastes which may be generated when organic ion-exchange media are used in water demineralization or decontamination operations at nuclear facilities. External factors affecting the relation between laboratory evaluations and field performance are emphasized. Initial experiments do not yet indicate substantial radiation dose-rate effects on radiolytic gas yields or acid product formation, when (fully swollen) sulfonic acid resins are irradiated in a sealed air environment. At the same time, oxygen gas is removed from the environment of irradiated resins. Interaction between mild steel coupons and acidic species produced in the irradiation induced decomposition of sulfonic acid resin results in irradiation enhanced corrosion. Corrosion rates depend on radiation dose rate, moisture content and resin chemical loading. In some cases, corrosion rates decrease with time, suggesting depletion of acidic species within the resin bed, or a synergistic interaction between resin and corrosion coupon. Implications of these and other results on evaluating field behavior of radwaste containing ion-exchange media are discussed. 4 figures, 2 tables

Microstructure and mechanical properties of composite resins subjected to accelerated artificial aging.

Science.gov (United States)

dos Reis, Andréa Cândido; de Castro, Denise Tornavoi; Schiavon, Marco Antônio; da Silva, Leandro Jardel; Agnelli, José Augusto Marcondes

2013-01-01

The aim of this study was to investigate the influence of accelerated artificial aging (AAA) on the microstructure and mechanical properties of the Filtek Z250, Filtek Supreme, 4 Seasons, Herculite, P60, Tetric Ceram, Charisma and Filtek Z100. composite resins. The composites were characterized by Fourier-transform Infrared spectroscopy (FTIR) and thermal analyses (Differential Scanning Calorimetry - DSC and Thermogravimetry - TG). The microstructure of the materials was examined by scanning electron microscopy. Surface hardness and compressive strength data of the resins were recorded and the mean values were analyzed statistically by ANOVA and Tukey's test (α=0.05). The results showed significant differences among the commercial brands for surface hardness (F=86.74, p<0.0001) and compressive strength (F=40.31, p<0.0001), but AAA did not affect the properties (surface hardness: F=0.39, p=0.53; compressive strength: F=2.82, p=0.09) of any of the composite resins. FTIR, DSC and TG analyses showed that resin polymerization was complete, and there were no differences between the spectra and thermal curve profiles of the materials obtained before and after AAA. TG confirmed the absence of volatile compounds and evidenced good thermal stability up to 200 °C, and similar amounts of residues were found in all resins evaluated before and after AAA. The AAA treatment did not significantly affect resin surface. Therefore, regardless of the resin brand, AAA did not influence the microstructure or the mechanical properties.

Natural Product Vibsanin A Induces Differentiation of Myeloid Leukemia Cells through PKC Activation.

Science.gov (United States)

Yu, Zu-Yin; Xiao, He; Wang, Li-Mei; Shen, Xing; Jing, Yu; Wang, Lin; Sun, Wen-Feng; Zhang, Yan-Feng; Cui, Yu; Shan, Ya-Jun; Zhou, Wen-Bing; Xing, Shuang; Xiong, Guo-Lin; Liu, Xiao-Lan; Dong, Bo; Feng, Jian-Nan; Wang, Li-Sheng; Luo, Qing-Liang; Zhao, Qin-Shi; Cong, Yu-Wen

2016-05-01

All-trans retinoic acid (ATRA)-based cell differentiation therapy has been successful in treating acute promyelocytic leukemia, a unique subtype of acute myeloid leukemia (AML). However, other subtypes of AML display resistance to ATRA-based treatment. In this study, we screened natural, plant-derived vibsane-type diterpenoids for their ability to induce differentiation of myeloid leukemia cells, discovering that vibsanin A potently induced differentiation of AML cell lines and primary blasts. The differentiation-inducing activity of vibsanin A was mediated through direct interaction with and activation of protein kinase C (PKC). Consistent with these findings, pharmacological blockade of PKC activity suppressed vibsanin A-induced differentiation. Mechanistically, vibsanin A-mediated activation of PKC led to induction of the ERK pathway and decreased c-Myc expression. In mouse xenograft models of AML, vibsanin A administration prolonged host survival and inhibited PKC-mediated inflammatory responses correlated with promotion of skin tumors in mice. Collectively, our results offer a preclinical proof of concept for vibsanin A as a myeloid differentiation-inducing compound, with potential application as an antileukemic agent. Cancer Res; 76(9); 2698-709. ©2016 AACR. ©2016 American Association for Cancer Research.

Radiation-initiated emulsion copolymerization of styrene and carboxylic acid monomers

International Nuclear Information System (INIS)

Egusa, S.; Makuuchi, K.

1982-01-01

The emulsion copolymerization of styrene and carboxylic acid monomers such as acrylic, methacrylic, and itaconic acids (AAc, MAAc, IAc) was studied by using 60 Co γ-rays as initiator and sodium dodecylsulfate as emulsifier. The polymerization behavior of these acid monomers was followed by simultaneous conductometric and potentiometric titrations for a latex sample taken in polymerization. The polymerization rate of these acid monomers increases in the following order of hydrophobicity: IAc < AAc < MAAc; this suggests that their polymerization sites are mainly the surface and/or subsurface regions of latex particles. The copolymerization rate of styrene and acid monomer increases with an increase in the acid monomer content for AAc and MAAc, whereas for IAc the rate decreases. The particle sizes determined by the stopped-flow method reveal that this variation of copolymerization rate cannot be explained by the number of growing particles and should be attributed to another factor; for instance, the transfer rate of styrene molecules from oil droplets to growing particles

Use of Monomer Fraction Data in the Parametrization of Association Theories

DEFF Research Database (Denmark)

Kontogeorgis, Georgios; Tsivintzelis, Ioannis; von Solms, Nicolas

2010-01-01

the monomer fraction of hydrogen bonding compounds and their mixtures. Monomer fraction data are obtained from spectroscopic measurements and they are available for a few compounds such as pure water and alcohols as well as for some alcohol–alkane and similar mixtures. These data are useful...... “improved” model parameters can be obtained if monomer fraction data are included in the parameter estimation together with vapor pressures and liquid densities. The expression “improved” implies parameters which can represent several pure compound properties as well as monomer fraction data for pure......, liquid densities and monomer fractions of water and alcohols. The 4C scheme is the best choice for water, while for methanol there is small difference between the 2B and 3B association schemes....

Investigation of an accident in a resins manufacturing site: The role of accelerator on polymerisation of methyl methacrylate

Energy Technology Data Exchange (ETDEWEB)

Casson, Valeria, E-mail: valeria.casson.moreno@gmail.com [Alma Mater Studiorum—Università di Bologna, Dipartimento di Ingegneria Chimica, Mineraria e delle Tecnologie Ambientali, Bologna (Italy); Dipartimento di Ingegneria Industriale, Via Marzolo 9, 35131 Padova (Italy); Snee, Tim, E-mail: Tim.Snee@hsl.gsi.gov.uk [Health and Safety Laboratory, Harpur Hill, Buxton, Derbyshire SK 179 JN (United Kingdom); Maschio, Giuseppe, E-mail: giuseppe.maschio@unipd.it [Dipartimento di Ingegneria Industriale, Via Marzolo 9, 35131 Padova (Italy)

2014-04-01

Highlights: • The accelerator produces an increase in the initial rate of polymerisation. • The accelerator increases the extent of polymerisation in certain conditions. • The accelerator decreases the induction time due to the presence of inhibitor. • Runaway reaction is more likely to occur in presence of the accelerator. • The experimental data support the hypothesis about the accident. - Abstract: This paper analyzes the effect of an accelerator on the polymerisation of methyl methacrylate (MMA). This study is based on the results of an investigation of an accident in a manufacturing site for resins located in the United Kingdom. As sequence of event to cause the accident the following was assumed: during an unattended batch process a runaway undesired polymerisation of methyl methacrylate occurred, generating rapid vaporisation of monomer, which in contact with an ignition source, led to an explosion followed by a fire. Since no initiator for the polymerisation reaction had been jet added to the blend, it was supposed that the accelerator contributed to the onset of the undesired polymerisation. The accelerator involved in the accident t has therefore been tested by differential scanning calorimetry and adiabatic calorimetry. The experimental data allowed the authors to prove the hypothesis made and to define safety ranges for the polymerisation reaction.

Differentiation-inducing factor-1 induces cyclin D1 degradation through the phosphorylation of Thr286 in squamous cell carcinoma

International Nuclear Information System (INIS)

Mori, Jun; Takahashi-Yanaga, Fumi; Miwa, Yoshikazu; Watanabe, Yutaka; Hirata, Masato; Morimoto, Sachio; Shirasuna, Kanemitsu; Sasaguri, Toshiyuki

2005-01-01

Differentiation-inducing factors (DIFs) are morphogens which induce cell differentiation in Dictyostelium. We reported that DIF-1 and DIF-3 inhibit proliferation and induce differentiation in mammalian cells. In this study, we investigated the effect of DIF-1 on oral squamous cell carcinoma cell lines NA and SAS, well differentiated and poorly differentiated cell lines, respectively. Although DIF-1 did not induce the expression of cell differentiation makers in these cell lines, it inhibited the proliferation of NA and SAS in a dose-dependent manner by restricting the cell cycle in the G 0 /G 1 phase. DIF-1 induced cyclin D1 degradation, but this effect was prevented by treatment with lithium chloride and SB216763, the inhibitors of glycogen synthase kinase-3β (GSK-3β). Depletion of endogenous GSK-3β by RNA interference also attenuated the effect of DIF-1 on cyclin D1 degradation. Therefore, we investigated the effect of DIF-1 on GSK-3β and found that DIF-1 dephosphorylated GSK-3β on Ser 9 and induced the nuclear translocation of GSK-3β, suggesting that DIF-1 activated GSK-3β. Then, we examined the effect of DIF-1 on cyclin D1 mutants (Thr286Ala, Thr288Ala, and Thr286/288Ala). We revealed that Thr286Ala and Thr286/288Ala mutants were highly resistant to DIF-1-induced degradation compared with wild-type cyclin D1, indicating that the phosphorylation of Thr 286 was critical for cyclin D1 degradation induced by DIF-1. These results suggest that DIF-1 induces degradation of cyclin D1 through the GSK-3β-mediated phosphorylation of Thr 286

Proteomic analysis of PC12 cell differentiation induced by ionizing radiation

International Nuclear Information System (INIS)

Zhang Junquan; Gao Ronglian; Chen Xiaohua; Wang Zhidong; Dong Bo; Rao Yalan; Hou Lili; Zhang Hao; Mao Bingzhi

2005-01-01

Objective: To explore the molecular mechanism of PC12 cell differentiation induced by ionizing radiation and screen the molecular target of nervous system injured by irradiation. Methods: PC12 cells were irradiated with 16 Gy 60 Co γ ray. Total proteins of normal and irradiated cells were prepared 48 hours after irradiation and separated with two dimensional gel electrophoresis. Some differential expressed proteins were characterized with mass spectrometry. Results: 876 differential expressed proteins were observed. Up-regulated expression of ubiquitin carboxyl-terminal hydratase L1 was found. Down-regulated expression of new protein similar to HP1α was found. Conclusion: The characterization of some differential expressed proteins through proteomic analysis would benefit the research of molecular mechanism of PC12 cell differentiation induced by ionizing radiation. (authors)

Development of critical molecular weight-property specifications for high performance polymers used as adhesives and composites

Science.gov (United States)

Kranbuehl, D. E.

1982-01-01

The polyimide resin, LARC-160, was prepared from diethyl-3, 3', 4,4'-benzophenone tetracarboxylate, ethyl-5-norbornene-2,3-dicarboxylate and Jeffamine AP-22. The imidization reactions of NE and BTDE were studied by HPLC, C-13-NMR and IR. NE imidizes slowly at 12 C; BTDE imidizes when the resin is heated above 100 C. Both imidization reactions proceed directly to the imide. Neither amic acid is present in significant quantities at any stage of the imidization reactions. The monomer mixture was stored at 12 C for periods up to 14 months. The effects of resin aging at this temperature on the chemical composition of the resin monomer mixture and the imidized polymer formed on curing were investigated. Aging the resin monomer mixture has the effect of partially advancing the imidization reaction. The average size of the cured polymer increases slightly with resin age.

Inhibition of the NAD-dependent protein deacetylase SIRT2 induces granulocytic differentiation in human leukemia cells.

Directory of Open Access Journals (Sweden)

Yoshitaka Sunami

Full Text Available Sirtuins, NAD-dependent protein deacetylases, play important roles in cellular functions such as metabolism and differentiation. Whether sirtuins function in tumorigenesis is still controversial, but sirtuins are aberrantly expressed in tumors, which may keep cancerous cells undifferentiated. Therefore, we investigated whether the inhibition of sirtuin family proteins induces cellular differentiation in leukemic cells. The sirtuin inhibitors tenovin-6 and BML-266 induce granulocytic differentiation in the acute promyelocytic leukemia (APL cell line NB4. This differentiation is likely caused by an inhibition of SIRT2 deacetylase activity, judging from the accumulation of acetylated α-tubulin, a major SIRT2 substrate. Unlike the clinically used differentiation inducer all-trans retinoic acid, tenovin-6 shows limited effects on promyelocytic leukemia-retinoic acid receptor α (PML-RAR-α stability and promyelocytic leukemia nuclear body formation in NB4 cells, suggesting that tenovin-6 does not directly target PML-RAR-α activity. In agreement with this, tenovin-6 induces cellular differentiation in the non-APL cell line HL-60, where PML-RAR-α does not exist. Knocking down SIRT2 by shRNA induces granulocytic differentiation in NB4 cells, which demonstrates that the inhibition of SIRT2 activity is sufficient to induce cell differentiation in NB4 cells. The overexpression of SIRT2 in NB4 cells decreases the level of granulocytic differentiation induced by tenovin-6, which indicates that tenovin-6 induces granulocytic differentiation by inhibiting SIRT2 activity. Taken together, our data suggest that targeting SIRT2 is a viable strategy to induce leukemic cell differentiation.

2D Numerical Modelling of the Resin Injection Pultrusion Process Including Experimental Resin Kinetics and Temperature Validation

DEFF Research Database (Denmark)

Rasmussen, Filip Salling; Sonne, Mads Rostgaard; Larsen, Martin

In the present study, a two-dimensional (2D) transient Eulerian thermo-chemical analysis of a carbon fibre epoxy thermosetting Resin Injection Pultrusion (RIP) process is carried out. The numerical model is implemented using the well known unconditionally stable Alternating Direction Implicit (ADI......) scheme. The total heat of reaction and the cure kinetics of the epoxy thermosetting are determined using Differential Scanning Calorimetry (DSC). A very good agreement is observed between the fitted cure kinetic model and the experimental measurements. The numerical steady state temperature predictions...

Mechanical, dielectric, and physicochemical properties of impregnating resin based on unsaturated polyesterimides

Science.gov (United States)

Fetouhi, Louiza; Petitgas, Benoit; Dantras, Eric; Martinez-Vega, Juan

2017-10-01

This work aims to characterize the dielectric and the mechanical properties of a resin based on an unsaturated polyesterimide diluted in methacrylate reactive diluents used in the impregnation of rotating machines. The broadband dielectric spectrometry and the dynamic mechanical analysis were used to quantify the changes in dielectric and mechanical properties of the network PEI resin, as a function of temperature and frequency. The network characterizations highlight the presence of two main relaxations, α and α', confirmed by the differential scanning calorimetry analysis, showing the complexity of the chemical composition of this resin. The dielectric spectroscopy shows a significant increase in the dielectric values due to an increase of the material conductivity, while the mechanical spectroscopy shows an important decrease of the polymer rigidity and viscosity expressed by an important decrease in the storage modulus. The PEI resin shows a high reactivity when it is submitted in successive heating ramps, which involves in a post-cross-linking reaction. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2016)", edited by Adel Razek

Solidification of ion exchange resins saturated with Na+ ions: Comparison of matrices based on Portland and blast furnace slag cement

Science.gov (United States)

Lafond, E.; Cau dit Coumes, C.; Gauffinet, S.; Chartier, D.; Stefan, L.; Le Bescop, P.

2017-01-01

This work is devoted to the conditioning of ion exchange resins used to decontaminate radioactive effluents. Calcium silicate cements may have a good potential to encapsulate spent resins. However, certain combinations of cement and resins produce a strong expansion of the final product, possibly leading to its full disintegration. The focus is placed on the understanding of the behaviour of cationic resins in the Na+ form in Portland or blast furnace slag (CEM III/C) cement pastes. During hydration of the Portland cement paste, the pore solution exhibits a decrease in its osmotic pressure, which causes a transient expansion of small magnitude of the resins. At 20 °C, this expansion takes place just after setting in a poorly consolidated material and is sufficient to induce cracks. In the CEM III/C paste, swelling of the resins also occurs, but before the end of setting, and induces limited stress in the matrix which is still plastic.

Base-catalyzed depolymerization of lignin : separation of monomers

Energy Technology Data Exchange (ETDEWEB)

Vigneault, A. [Sherbrooke Univ., PQ (Canada). Dept. of Chemical Engineering; Johnson, D.K. [National Renewable Energy Laboratory, Golden, CO (United States); Chornet, E. [Sherbrooke Univ., PQ (Canada). Dept. of Chemical Engineering; National Renewable Energy Laboratory, Golden, CO (United States)

2007-12-15

Biofuels produced from residual lignocellulosic biomass range from ethanol to biodiesel. The use of lignin for the production of alternate biofuels and green chemicals has been studied with particular emphasis on the structure of lignin and its oxyaromatic nature. In an effort to fractionate lignocellulosic biomass and valorize specific constitutive fractions, the authors developed a strategy for the separation of 12 added value monomers produced during the hydrolytic base catalyzed depolymerization (BCD) of a Steam Exploded Aspen Lignin. The separation strategy was similar to vanillin purification to obtain pure monomers, but combining more steps after the lignin depolymerization such as acidification, batch liquid-liquid-extraction (LLE), followed by vacuum distillation, liquid chromatography (LC) and crystallization. The purpose was to develop basic data for an industrial size process flow diagram, and to evaluate both the monomer losses during the separation and the energy requirements. Experimentally testing of LLE, vacuum distillation and flash LC in the laboratory showed that batch vacuum distillation produced up to 4 fractions. Process simulation revealed that a series of 4 vacuum distillation columns could produce 5 distinct monomer streams, of which 3 require further chromatography and crystallization operations for purification. 22 refs., 4 tabs., 8 figs.

Studies on curing effect of phosphite monomer by EB radiation in the air

International Nuclear Information System (INIS)

Xiao, B.; Zhou, Y.; Li, S.; Luo, M.; Wang, X.; Zhao, P.

2000-01-01

A new type phosphite active monomer was synthesized. The resisting oxygen inhibition effect of this monomer and the effects of irradiation dose and concentration of phosphite active monomer on curing were studied. At the same time, curing results were analysed, through gel content and IR spectrum. The excellent resisting oxygen inhibition result of this phosphite active monomer was shown by experiments. EB radiation curing in the air was successfully carried out by the phosphite active monomer. (author)

Effect of solvent content on resin hybridization in wet dentin bonding.

Science.gov (United States)

Wang, Yong; Spencer, Paulette; Yao, Xiaomei; Brenda, Bohaty

2007-09-15

With wet bonding techniques, the channels between the demineralized dentin collagen fibrils are filled with debris, solvent, and water. Commercial adhesives include solvents such as ethanol or acetone to facilitate resin-infiltration into this wet substrate. Under in vivo conditions, the solvent may be diluted because of repeated exposure of the material to the atmosphere, or concentrated because of separation of the bonding liquids into layers within the bottle. The purpose of this study was to investigate the effect of different concentrations of ethanol (10-50%) on infiltration of the adhesive resin and collagen fibril encapsulation in the adhesive/dentin interface using light microscopy, micro-Raman spectroscopy, and scanning electron microscopy. The results indicated that under wet bonding conditions the hybridization process was highly sensitive to the initial solvent concentration in the adhesive system. The staining and scanning electron microscopy results showed that the quality of the interfacial hybrid layer was poor at the lower (10%) or higher (50%) ethanol content. Micro-Raman analysis indicated that there was a distinct difference in the degree of adhesive penetration among adhesives containing different concentrations of ethanol. Adhesives containing 10 or 50% ethanol did not realize effective penetration; the penetration of the adhesive monomers increased dramatically when the initial ethanol content was 30%. The amount of solvents are essential for achieving effective bonding to dentin. Copyright 2007 Wiley Periodicals, Inc.

Thermotropic resin systems. Relationships between formulation parameters, material structure and optical properties

Energy Technology Data Exchange (ETDEWEB)

Resch, Katharina [Polymer Competence Center Leoben GmbH, Leoben (Austria); Wallner, Gernot M. [Univ. of Leoben (Austria)

2008-07-01

This paper focuses on a comprehensive characterization of various thermotropic resins under polymer physical aspects. Numerous thermotropic layers were produced under systematic variation of resin base, thermotropic additives and additive concentration. A detailed investigation of optical properties, switching temperature, switching process and residual transmittance was performed with a UV/Vis/NIR spectrophotometer. Switching temperatures are compared with thermal transitions in the material determined by Differential Scanning Calorimetry (DSC). Whereas the different film types show a direct solar transparency between 64 and 83% in the clear state, the direct solar transmittance decreases to values of about 27% to 80% above the switching temperature. In general the thermotropic resins are characterized by a steep and rapid switching process. The switching temperature can be adapted by varying the additives. The comparison of films thermal transitions with the switching performance reveals a good correlation. (orig.)

Aminoalkylated Merrifield Resins Reticulated by Tris-(2-chloroethyl Phosphate for Cadmium, Copper, and Iron (II Extraction

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Mokhtar Dardouri

2015-01-01

Full Text Available We aimed to synthesize novel substituted polymers bearing functional groups to chelate heavy metals during depollution applications. Three polyamine functionalized Merrifield resins were prepared via ethylenediamine (EDA, diethylenetriamine (DETA, and triethylenetetramine (TETA modifications named, respectively, MR-EDA, MR-DETA, and MR-TETA. The aminoalkylated polymers were subsequently reticulated by tris-(2-chloroethyl phosphate (TCEP to obtain new polymeric resins called, respectively, MR-EDA-TCEP, MR-DETA-TCEP, and MR-TETA-TCEP. The obtained resins were characterized via attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR, elemental analysis (EA, and thermogravimetric (TGA, thermodynamic (DTA, and differential thermogravimetric (DTG analysis. The synthesized resins were then assayed to evaluate their efficiency to extract metallic ions such as Cd2+, Cu2+, and Fe2+ from aqueous solutions.

Inverse opal pH sensors with various protic monomers copolymerized with polyhydroxyethylmethacrylate hydrogel

International Nuclear Information System (INIS)

Shin, Jinsub; Han, Sung Gu; Lee, Wonmok

2012-01-01

Highlights: ► We polymerized four different inverse opal pH sensors by using vinyl monomers containing acidic or basic substituents. ► Stepwise swelling response from polyprotic acid sensor was investigated. ► Opposite color changing responses were obtained for acidic and basic sensors. ► Composite pH sensor with wide pH sensing range was fabricated by mixing different monomers. ► Both acid and base sensors show the response time as fast as ∼10 s. - Abstract: pH sensitive inverse opal sensors were synthesized using various vinyl monomers containing acidic or basic substituents. Acrylic acid (AA), vinylphosphonic acid (VPA), vinylimidazole (VI), and dimethylaminoethylmethacrylic acid (DMAEMA) were respectively copolymerized with hydroxyethylmethacrylate (HEMA), the building block monomer of the hydrogel via UV-initiated photopolymerization. Opal templating and subsequent template removal enabled the fabrication of four inverse opal (IO) hydrogel colorimetric sensors, which responded to pH in different fashions. pH-dependent swelling of the IO hydrogel induced the red-shift of the diffracted color. The sensors containing AA or VPA, the proton donating monomers showed the color shifts from green to red with pH increase due to the increased concentration of carboxylate anions bound to the hydrogel. Diprotic VPA sensor exhibited two-step increases of diffracted wavelengths at its pK a1 and pK a2 respectively. The sensors containing proton acceptors, VI and DMAEMA showed the pH-dependent color changes in an opposite way to the AA sensor and the VPA sensor since their ionizations take place by lowering pH due to the protonation at the amino groups. The shapes of pH response curves of VI and DMAEMA sensors were similar but pK b s were different from each other. Optical diffraction responses of four sensors were compared with the calculated concentration ratios of the ionized species to the total monomer with pH variation, and a deswelling effect in the

Preparation of metal ion exchange resin by radiation-induced graft copolymerization

International Nuclear Information System (INIS)

Nakase, Yoshiaki; Akasaka, Nobuhiro.

1982-06-01

Radiation-induced graft copolymerization of 2-acrylamide-2-methyl propane sulfonic acid (AMPS) onto polyvinylchloride (PVC) and polyvinylidene chloride resin (PVD) was investigated in the water-acetone system and their adsorptive activities to metal ion were also examined. In the case of PVC, the degree of grafting increased with the increase of acetone content, but the adsorptive activity to metal ions (mainly lithic ion) became maximum in the system with water/acetone of 2/3. Grafted PVC prepared at about 35 0 C and at a higher concentration of AMPS showed higher adsorption activity than the other cases. In the case of PVD, a similar result was obtained with the case of PVC except the temperature dependence and effect of swelling agent. Polymerizations at temperatures of 35 and 50 0 C showed no effect on the degree of grafting, and the usage of a swelling agent was quite effective to the adsorptive activity. Glass transition temperature of the grafted copolymer was the same as that of original polymer, and their thermal stability was confirmed up to the temperature at which homopolymer of AMPS decomposed, about 180 0 C. (author)

Platelet-Released Growth Factors Induce Differentiation of Primary Keratinocytes

Science.gov (United States)

Tohidnezhad, Mersedeh; Lammel, Justus; Lippross, Sebastian; Behrendt, Peter; Klüter, Tim; Pufe, Thomas; Jahr, Holger; Cremer, Jochen; Rademacher, Franziska; Gläser, Regine; Harder, Jürgen

2017-01-01

Autologous thrombocyte concentrate lysates, for example, platelet-released growth factors, (PRGFs) or their clinically related formulations (e.g., Vivostat PRF®) came recently into the physicians' focus as they revealed promising effects in regenerative and reparative medicine such as the support of healing of chronic wounds. To elucidate the underlying mechanisms, we analyzed the influence of PRGF and Vivostat PRF on human keratinocyte differentiation in vitro and on epidermal differentiation status of skin wounds in vivo. Therefore, we investigated the expression of early (keratin 1 and keratin 10) and late (transglutaminase-1 and involucrin) differentiation markers. PRGF treatment of primary human keratinocytes decreased keratin 1 and keratin 10 gene expression but induced involucrin and transglutaminase-1 gene expression in an epidermal growth factor receptor- (EGFR-) dependent manner. In concordance with these results, microscopic analyses revealed that PRGF-treated human keratinocytes displayed morphological features typical of keratinocytes undergoing terminal differentiation. In vivo treatment of artificial human wounds with Vivostat PRF revealed a significant induction of involucrin and transglutaminase-1 gene expression. Together, our results indicate that PRGF and Vivostat PRF induce terminal differentiation of primary human keratinocytes. This potential mechanism may contribute to the observed beneficial effects in the treatment of hard-to-heal wounds with autologous thrombocyte concentrate lysates in vivo. PMID:28808357

Platelet-Released Growth Factors Induce Differentiation of Primary Keratinocytes

Directory of Open Access Journals (Sweden)

Andreas Bayer

2017-01-01

Full Text Available Autologous thrombocyte concentrate lysates, for example, platelet-released growth factors, (PRGFs or their clinically related formulations (e.g., Vivostat PRF® came recently into the physicians’ focus as they revealed promising effects in regenerative and reparative medicine such as the support of healing of chronic wounds. To elucidate the underlying mechanisms, we analyzed the influence of PRGF and Vivostat PRF on human keratinocyte differentiation in vitro and on epidermal differentiation status of skin wounds in vivo. Therefore, we investigated the expression of early (keratin 1 and keratin 10 and late (transglutaminase-1 and involucrin differentiation markers. PRGF treatment of primary human keratinocytes decreased keratin 1 and keratin 10 gene expression but induced involucrin and transglutaminase-1 gene expression in an epidermal growth factor receptor- (EGFR- dependent manner. In concordance with these results, microscopic analyses revealed that PRGF-treated human keratinocytes displayed morphological features typical of keratinocytes undergoing terminal differentiation. In vivo treatment of artificial human wounds with Vivostat PRF revealed a significant induction of involucrin and transglutaminase-1 gene expression. Together, our results indicate that PRGF and Vivostat PRF induce terminal differentiation of primary human keratinocytes. This potential mechanism may contribute to the observed beneficial effects in the treatment of hard-to-heal wounds with autologous thrombocyte concentrate lysates in vivo.

Experimental Studies on the Synthesis and Performance of Boron-containing High Temperature Resistant Resin Modified by Hydroxylated Tung Oil

Science.gov (United States)

Zhang, J. X.; Y Ren, Z.; Zheng, G.; Wang, H. F.; Jiang, L.; Fu, Y.; Yang, W. Q.; He, H. H.

2017-12-01

In this work, hydroxylated tung oil (HTO) modified high temperature resistant resin containing boron and benzoxazine was synthesized. HTO and ethylenediamine was used to toughen the boron phenolic resin with specific reaction. The structure of product was studied by Fourier-transform infrared spectroscopy(FTIR), and the heat resistance was tested by Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis(TGA). The results indicated that the conjugated triene structure of HTO was involved in the crosslinking of the heating curing progress, and in addition, the open-loop polymerization reaction of benzoxazine resin during heating can effectively reduce the curing temperature of the resin and reduce the release of small molecule volatiles, which is advantageous to follow-up processing. DSC data showed that the initial decomposition temperature of the resin is 350-400 °C, the carbon residue rate under 800 °C was 65%. It indicated that the resin has better heat resistance than normal boron phenolic resin. The resin can be used as an excellent ablative material and anti-friction material and has a huge application market in many fields.

Polyvinyl chloride resin

International Nuclear Information System (INIS)

Kim, Hong Jae

1976-06-01

This book contains polyvinyl chloride resin industry with present condition such as plastic industry and polyvinyl chloride in the world and Japan, manufacture of polyvinyl chloride resin ; suspension polymerization and solution polymerization, extruding, injection process, hollow molding vinyl record, vacuum forming, polymer powders process, vinyl chloride varnish, vinyl chloride latex, safety and construction on vinyl chloride. Each chapter has descriptions on of process and kinds of polyvinyl chloride resin.

Dynamic mechanical thermal analysis of composite resins with CQ and PPD as photo-initiators photoactivated by QTH and LED units.

Science.gov (United States)

Brandt, William Cunha; Silva, Cristina Gomes; Frollini, Elisabete; Souza-Junior, Eduardo Jose Carvalho; Sinhoreti, Mário Alexandre Coelho

2013-08-01

The aim of this study was to evaluate the thermal and mechanical properties of the composite resins containing the photo-initiators camphorquinone (CQ) and/or phenyl-propanodione (PPD) when photoactivated with halogen lamp (XL2500/3M-ESPE), monowave (UltraBlueIS/DMC) and polywave (UltraLume5/Ultradent) LED units. A blend of BisGMA, UDMA, BisEMA and TEGDMA was prepared with the same wt% of photo-initiators CQ and/or PPD and 65wt% of silaneted filler particles. Compression strength (CS), diametral tensile strength (DTS) and diametral modulus (DM) were tested. Thermogravimetric analysis (TGA) was made and the lost residual monomer were verified. Dynamic mechanical thermal analysis (DMTA) was used for to analyze the glass transition temperature (Tg) and the storage modulus in 37°C. Degree of conversion (DC) was accomplished in the same samples of DMA using middle-infrared spectroscopy (mid-IR). CQ, CQ/PPD and PPD obtained the same results for all mechanical properties (CS, DTS and DM), lost residual monomer and storage modulus in 37°C, regardless LCU used. The results of Tg showed that the combination PPD-UltraLume5 produced the highest values. DC showed that the combination CQ-UltraLume5 resulted in the highest values and PPD-XL2500 in the lowest DC values. The study shows that PPD is not only effective photosensitizers, but also photocrosslinking agents for dental composite resins with a similar efficiency to CQ. Copyright © 2013 Elsevier Ltd. All rights reserved.

BMP-2 Induced Expression of Alx3 That Is a Positive Regulator of Osteoblast Differentiation.

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Takashi Matsumoto

Full Text Available Bone morphogenetic proteins (BMPs regulate many aspects of skeletal development, including osteoblast and chondrocyte differentiation, cartilage and bone formation, and cranial and limb development. Among them, BMP-2, one of the most potent osteogenic signaling molecules, stimulates osteoblast differentiation, while it inhibits myogenic differentiation in C2C12 cells. To evaluate genes involved in BMP-2-induced osteoblast differentiation, we performed cDNA microarray analyses to compare BMP-2-treated and -untreated C2C12 cells. We focused on Alx3 (aristaless-like homeobox 3 which was clearly induced during osteoblast differentiation. Alx3, a homeobox gene related to the Drosophilaaristaless gene, has been linked to developmental functions in craniofacial structures and limb development. However, little is known about its direct relationship with bone formation. In the present study, we focused on the mechanisms of Alx3 gene expression and function during osteoblast differentiation induced by BMP-2. In C2C12 cells, BMP-2 induced increase of Alx3 gene expression in both time- and dose-dependent manners through the BMP receptors-mediated SMAD signaling pathway. In addition, silencing of Alx3 by siRNA inhibited osteoblast differentiation induced by BMP-2, as showed by the expressions of alkaline phosphatase (Alp, Osteocalcin, and Osterix, while over-expression of Alx3 enhanced osteoblast differentiation induced by BMP-2. These results indicate that Alx3 expression is enhanced by BMP-2 via the BMP receptors mediated-Smad signaling and that Alx3 is a positive regulator of osteoblast differentiation induced by BMP-2.

Differential expression of ozone-induced gene during exposures to ...

African Journals Online (AJOL)

Differential expression of ozone-induced gene during exposures to salt stress in Polygonum sibiricum Laxm leaves, stem and underground stem. ... PcOZI-1 mRNA in untreated plants was detected at low levels in underground stem, leaves and at higher levels in stem. PcOZI-1 mRNA accumulation was transiently induced ...

Synthesis of a hollow fiber type porous chelating resin containing the amide oxime group by radiation induced graft polymerization for the uranium recovery

International Nuclear Information System (INIS)

Hori, Takahiro; Saito, Kyoichi; Furusaki, Shintaro; Sugo, Takanobu; Okamoto, Jiro.

1986-01-01

A hollow fiber type porous chelating resin containing amide oxime as a functional group was synthesized and used as an adsorbent for the recovery of uranium. Hollow fiber type porous polyethylene was used as a base polymer. Acrylonitrile was grafted onto it by the radiation-induced graft polymerization. By changing the reaction time, four kinds of graft polymer were obtained. The degree of grafting ranged from 79 % to 127 %. Each resin was soaked in hydroxylamine solution, and the cyano group was converted to amide oxime group. By elemental analysis, the amount of nitrogen introduced on the graft polymer resin in amidoximation was determined to range from 4.3 mmol to 8.5 mmol per 1 g of base polymer. Most of the nitrogen is considered to belong to the amide oxime group. The pore radius, which was initially distributed broadly from about 500 A to 10000 A for the base polymer, was changed to about 1000 A with narrow distribution by the grafting. The pore volume was 1.2 ∼ 1.4 cm 3 per 1 gram of the amide oxime resin, which was about half of that of the initial base polymer. But the pore volume per 1 g base polymer of the amide oxime resin increased with an increase in the grafting degree, e.g. 4.5 cm 3 /g base polymer at 127 % of grafting degree. Specific surface area, which was 30 m 2 /g in base polymer, decreased with an increase in the grafting degree, e.g. 15 m 2 /g at 127 % of grafting degree. Both the amounts of the adsorbed hydrochloric acid and the adsorbed copper were about 1.5 times of the amount of nitrogen introduced in the amidoximation. The reason is considered to be caused by the formation of hydroxamic acid and amide from the measurements of the IR spectra. The amount of uranium adsorbed on the resin was 64 % of the amount of nitrogen introduced in the amidoximation. (author)

Analysis of the effects of reaction parameters upon the molecular weight of an aromatic poly(hydrazide) through experimental design

International Nuclear Information System (INIS)

Gomes, Dominique; Pinto, Jose Carlos; Borges, Cristiano P.; Nunes, Suzana P.

2001-01-01

Samples of an aromatic poly(hydrazide) were synthesized through low temperature solution polycondensation reactions. Monomers were characterized by nuclear magnetic resonance (NMR) and thermal analysis. The polymer material was characterized by intrinsic viscosity measurements and by NMR. The thermal behavior of the polymer samples was studied by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of various factors that influence the course of the polymerization reaction, such as concentration of monomer and electrolyte (LiCl) in the reaction medium, purity of the monomers, reaction temperature and reaction time, were investigated. Reaction conditions were then optimized in order to allow the preparation of high molecular weight polymer resins. Values of intrinsic viscosity obtained for the poly(hydrazide) in N-methyl-2-pyrrolidone were as high as 1.51 dL/g. (author)

Ligustrazine monomer against cerebral ischemia-reperfusion injury

Directory of Open Access Journals (Sweden)

Hai-jun Gao

2015-01-01

Full Text Available Ligustrazine (2,3,5,6-tetramethylpyrazine is a major active ingredient of the Szechwan lovage rhizome and is extensively used in treatment of ischemic cerebrovascular disease. The mechanism of action of ligustrazine use against ischemic cerebrovascular diseases remains unclear at present. This study summarizes its protective effect, the optimum time window of administration, and the most effective mode of administration for clinical treatment of cerebral ischemia/reperfusion injury. We examine the effects of ligustrazine on suppressing excitatory amino acid release, promoting migration, differentiation and proliferation of endogenous neural stem cells. We also looked at its effects on angiogenesis and how it inhibits thrombosis, the inflammatory response, and apoptosis after cerebral ischemia. We consider that ligustrazine gives noticeable protection from cerebral ischemia/reperfusion injury. The time window of ligustrazine administration is limited. The protective effect and time window of a series of derivative monomers of ligustrazine such as 2-[(1,1-dimethylethyloxidoimino]methyl]-3,5,6-trimethylpyrazine, CXC137 and CXC195 after cerebral ischemia were better than ligustrazine.

In situ polymerization of monomers for polyphenylquinoxaline-graphite fiber composites

Science.gov (United States)

Serafini, T. T.; Delvigs, P.; Vannucci, R. D.

1974-01-01

In situ polymerization of monomers was used to prepare graphite-fiber-reinforced polyphenylquinoxaline composites. Six different monomer combinations were investigated. Composite mechanical property retention characteristics were determined at 316 C (600 F) over an extended time period.

Isolation of furocoumarins from bergamot fruits as HL-60 differentiation-inducing compounds.

Science.gov (United States)

Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M

1999-10-01

The HL-60 differentiation-inducing compounds in bergamot fruits were isolated with column chromatography and identified as bergamottin, bergapten, and citropten by (1)H and (13)C NMR. Their HL-60 differentiation-inducing activity was measured by examining nitro blue tetrazolium (NBT) reducing, nonspecific acid esterase (NSE), specific esterase (SE), and phagocytic activities, and bergamottin showed the strongest activity among the coumarins isolated from bergamot fruits. The structure-activity relationship obtained from HL-60 differentiation assay suggests that hydrophobicity of furocoumarins is correlated with their activity.

Kinetics of the monomer-dimer reaction of yeast hexokinase PI.

Science.gov (United States)

Hoggett, J G; Kellett, G L

1992-10-15

Kinetic studies of the glucose-dependent monomer-dimer reaction of yeast hexokinase PI at pH 8.0 in the presence of 0.1 M-KCl have been carried out using the fluorescence temperature-jump technique. A slow-relaxation effect was observed which was attributed from its dependence on enzyme concentration to the monomer-dimer reaction; the reciprocal relaxation times tau-1 varied from 3 s-1 at low concentrations of glucose to 42 s-1 at saturating concentrations. Rate constants for association (kass.) and dissociation (kdiss.) were determined as a function of glucose concentration using values of the equilibrium association constant of the monomer-dimer reaction derived from sedimentation ultracentrifugation studies under similar conditions, and also from the dependence of tau-2 on enzyme concentration. kass. was almost independent of glucose concentration and its value (2 x 10(5) M-1.s-1) was close to that expected for a diffusion-controlled process. The influence of glucose on the monomer-dimer reaction is entirely due to effects on kdiss., which increases from 0.21 s-1 in the absence of glucose to 25 s-1 at saturating concentrations. The monomer and dimer forms of hexokinase have different affinities and Km values for glucose, and the results reported here imply that there may be a significant lag in the response of the monomer-dimer reaction to changes in glucose concentrations in vivo with consequent hysteretic effects on the hexokinase activity.

Experimental resin cements containing bioactive fillers reduce matrix metalloproteinase-mediated dentin collagen degradation.

Science.gov (United States)

Osorio, Raquel; Yamauti, Monica; Sauro, Salvatore; Watson, Thimoty F; Toledano, Manuel

2012-09-01

Collagen dentin matrix may represent a suitable scaffold to be remineralized in the presence of bioactive materials. The purpose of this study was to determine if experimental resin cements containing bioactive fillers may modulate matrix metalloproteinase-mediated collagen degradation of etched dentin. Human dentin beams demineralized using 10% phosphoric acid or 0.5 mol/L EDTA were infiltrated with the following experimental resins: (1) unfilled resin, (2) resin with Bioglass 45S5 particles (Sylc; OSspray Ltd, London, UK), and (3) resin with β-tricalcium phosphate-modified calcium silicate cement (HCAT-β) particles. The filler/resin ratio was 40/60 wt%. The specimens were stored in artificial saliva, and the determination of C-terminal telopeptide (ICTP) was performed by radioimmunoassay after 24 hours, 1 week, and 4 weeks. Scanning electron microscopic analysis of dentin surfaces after 4 weeks of storage was also executed. Collagen degradation was prominent both in phosphoric acid and EDTA-treated dentin. Resin infiltration strongly reduced the MMP activity in demineralized dentin. Resin-containing Bioglass 45S5 particles exerted higher and more stable protection of collagen at all tested dentin states and time points. HCAT-β induced collagen protection from MMPs only in EDTA-treated specimens. Dentin remineralization was achieved when dentin was infiltrated with the resin cements containing bioactive fillers. MMP degradation of dentin collagen is strongly reduced in resin-infiltrated dentin. The inclusion of Bioglass 45S5 particles exerted an additional protection of collagen during dentin remineralization. Copyright © 2012 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Encapsulation of dye molecules into mesoporous polymer resin and mesoporous polymer-silica films by an evaporation-induced self-assembly method

Energy Technology Data Exchange (ETDEWEB)

Chi Yue; Li Nan; Tu Jinchun; Zhang Yujie [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Li Xiaotian, E-mail: xiaotianli@jlu.edu.c [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Shao Changlu, E-mail: clshao@nenu.edu.c [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China)

2010-03-15

Polymer resin and polymer-silica films with highly ordered mesostructure have been used as host materials to encapsulate DCM (4-(dicyanomethylene) -2-methyl-6-(4-dimethylaminostyryl)-4h-pyran), a kind of fluorescent dye, through evaporation-induced self-assembly method (EISA). After encapsulation, the composites show significant blue-shift in photoluminescence (PL) spectra. Particularly, by changing the excitation wavelength, the samples show different emission bands. These phenomena are related to the mesostructure and the positions of DCM molecules in the host.

EPICOR-II resin degradation results from first resin samples of PF-8 and PF-20

International Nuclear Information System (INIS)

McConnell, J.W. Jr.; Sanders, R.D. Sr.

1985-12-01

The 28 March 1979 accident at Three Mile Island Unit 2 released approximately 560,000 gallons of contaminated water to the Auxiliary and Fuel Handling Buildings. The water was decontaminated using a demineralization system called EPICOR-II developed by Epicor, Inc. The Low-Level Waste Data Base Development - EPICOR-II Resin/Liner Investigation Project is studying the chemical and physical conditions of the synthetic ion exchange resins found in several EPICOR-II prefilters. This report summarizes results and analyses of the first sampling of ion exchange resins from EPICOR-II prefilters PE-8 and -20. Results are compared with baseline data from tests performed on unirradiated Epicor, Inc. resins to determine if degradation has occurred due to the high internal radiation dose received by the EPICOR-II resins. Results also are compared with recent findings on resin degradation by Battelle Columbus Laboratories and Brookhaven National Laboratory. Analyses comparing test results of resins from EPICOR-II prefilters PF-8 and -20 with unirradiated resins obtained from Epicor, Inc. show resin degradation has occurred in some of the EPICOR-II resins examined. The mechanism of degradation is compared with work of other researchers and is consistent with their findings. The strong acid cation resins (divinylbenzene, styrene base structure) are losing effective cross-linking along with scission of functional groups and are experiencing first an increase and eventually a decrease in total exchange capacity as the absorbed radiation dose increases. The phenolic cation resins (phenol-formaldehyde base structure) show a loss of effective cross-linking and oxidation of the polymer chain. Analyses of resins removed from EPICOR-II prefilters PF-8 and -20 over the next several years should show a further increase in degradation

Electron beam induced cationic polymerization of epoxy resins. Dependence of Tg on conversion

International Nuclear Information System (INIS)

Degrand, H.; Cazaux, F.; Coqueret, X.

2002-01-01

Complete text of publication follows. The high-energy radiation curing of monomer blends polymerizing by a free radical or by a cationic mechanism receives increasing attention in the perspective of high performance composite materials. In the present work, we have focused our attention on epoxy formulations as models of the matrices polymerizing by a cationic mechanism that could be used in fiber-reinforced composites for aerospace applications. We have examined the progress of the electron beam (EB) induced polymerization of diglycidylether of bisphenol A (DGEBA) in the presence of a diaryliodonium salt (DAIS) by FTIR spectroscopy and by dynamic mechanical thermal analysis (DMA). The obtained results allow to draw the gradual increase of the temperature for the network thermomechanical transition (T a , associated with the glass transition temperature T g ) over a broad range of conversion (p) and reveal a peculiar behavior at high conversion. In this domain (p > 0.90), the material's T g is shown to decrease when conversion approaches unity. Moreover, the post-irradiation thermal treatment of the materials, that generally yields effective 'dark curing', appears to induce a decrease of T g , with an amplitude correlated with the amount of DAIS in the formulation. Owing to the particular nature of the propagating centers in cationic polymerisation, the thermal relaxation of ionic clusters trapped in the glassy matrix can be reasonably invoked as a possible cause for this behavior

Application of linear pH gradients for the modeling of ion exchange chromatography: Separation of monoclonal antibody monomer from aggregates.

Science.gov (United States)

Kluters, Simon; Wittkopp, Felix; Jöhnck, Matthias; Frech, Christian

2016-02-01

The mobile phase pH is a key parameter of every ion exchange chromatography process. However, mechanistic insights into the pH influence on the ion exchange chromatography equilibrium are rare. This work describes a mechanistic model capturing salt and pH influence in ion exchange chromatography. The pH dependence of the characteristic protein charge and the equilibrium constant is introduced to the steric mass action model based on a protein net charge model considering the number of amino acids interacting with the stationary phase. This allows the description of the adsorption equilibrium of the chromatographed proteins as a function of pH. The model parameters were determined for a monoclonal antibody monomer, dimer, and a higher aggregated species based on a manageable set of pH gradient experiments. Without further modification of the model parameters the transfer to salt gradient elution at fixed pH is demonstrated. A lumped rate model was used to predict the separation of the monoclonal antibody monomer/aggregate mixture in pH gradient elution and for a pH step elution procedure-also at increased protein loadings up to 48 g/L packed resin. The presented model combines both salt and pH influence and may be useful for the development and deeper understanding of an ion exchange chromatography separation. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Coupled acoustic-gravity field for dynamic evaluation of ion exchange with a single resin bead.

Science.gov (United States)

Kanazaki, Takahiro; Hirawa, Shungo; Harada, Makoto; Okada, Tetsuo

2010-06-01

A coupled acoustic-gravity field is efficient for entrapping a particle at the position determined by its acoustic properties rather than its size. This field has been applied to the dynamic observation of ion-exchange reactions occurring in a single resin bead. The replacement of counterions in an ion-exchange resin induces changes in its acoustic properties, such as density and compressibility. Therefore, we can visually trace the advancement of an ion-exchange reaction as a time change in the levitation position of a resin bead entrapped in the field. Cation-exchange reactions occurring in resin beads with diameters of 40-120 microm are typically completed within 100-200 s. Ion-exchange equilibrium or kinetics is often evaluated with off-line chemical analyses, which require a batch amount of ion exchangers. Measurements with a single resin particle allow us to evaluate ion-exchange dynamics and kinetics of ions including those that are difficult to measure by usual off-line analyses. The diffusion properties of ions in resins have been successfully evaluated from the time change in the levitation positions of resin beads.

Novel Alkyd-Type Coating Resins Produced Using Cationic Polymerization [PowerPoint

Energy Technology Data Exchange (ETDEWEB)

Chisholm, Bret; Kalita, Harjyoti; Alam, Samim; Jayasooriyamu, Anurad; Fernando, Shashi; Samanata, Satyabrata; Bahr, James; Selvakumar, Sermadurai; Sibi, Mukund; Vold, Jessica; Ulven, Chad

2014-04-07

Novel, partially bio-based poly(vinyl ether) copolymers derived from soybean oil and cyclohexyl vinyl ether (CHVE) were produced by cationic polymerization and investigated for application as alkyd-type surface coatings. Compared to conventional alkyd resins, which are produced by high temperature melt condensation polymerization, the poly(vinyl ether)s provide several advantages. These advantages include miler, more energy efficient polymer synthesis, elimination of issues associated with gelation during polymer synthesis, production of polymers with well-defined composition and relatively narrow molecular weight distribution, and elimination of film formation and physical property issues associated with entrained monomers, dimers, trimmers, etc. The results of the studied showed that the thermal, mechanical, and physical properties of the coatings produced from these novel polymers varied considerable as a function of polymer composition and cure temperature. Overall, the results suggest a good potential for these novel copolymers to be used for coatings cured by autoxidation.

Hyperbranched polyester: single route synthesis, characterization and evaluation as impact modifier of an epoxy resin; Poliester hiperramificado: sintese por uma rota simples, caracterizacao e avaliacao como modificador de impacto de uma resina epoxi

Energy Technology Data Exchange (ETDEWEB)

Miranda, B.H.S.; Sousa, A.R., E-mail: rangel@deii.cefetmg.br [Centro Federal de Educacao Tecnologica de Minas Gerais (DEMAT/CEFET-MG), Belo Horizonte (Brazil). Departamento de Engenharia de Materiais; Alves, A.P.P.; Silva, G.G. [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte (Brazil). Departamento de Quimica. Lab. de Materiais Polimericos Multicomponentes

2015-07-01

Two hyperbranched polyesters were obtained using glycerol and adipic acid as monomers, they were characterized through nuclear magnetic resonance ({sup 13}C NMR) to branching degree determination, size exclusion chromatography to molar mass obtention and thermogravimetric analysis (TGA) to evaluate the thermal stability. The polyesters synthesized were added to epoxy resin, at 10% by weight, to evaluate the implication on mechanical properties, impact and stress strain, and thermal (glassy transition temperature - Tg). We observed that rising the synthesis time from 6 to 15,5 hours the degree of branching, molar mass and thermal stability of the polyester increased. The addition of hyperbranched polyesters did not change the mechanical properties of epoxy resin significantly, but the Tg was reduced. (author)

Dimethyl sulfoxide-inducible cytoplasmic factor involved in erythroid differentiation in mouse erythroleukemia (Friend) cells

International Nuclear Information System (INIS)

Watanabe, T.; Oishi, M.

1987-01-01

A previous report described an intracellular factor (differentiation-inducing factor I, or DIF-I) that seem to play a role in erythroid differentiation in mouse erythroleukemia (MEL) cells. The authors have detected another erythroid-inducing factor in cell-free extracts from dimethyl sulfoxide- or hexamethylenebis(acetamide)-treated MEL cells, which acts synergistically with DIF-I. The partially purified factor (termed DIF-II) triggered erythroid differentiation when introduced into undifferentiated MEL cells that had been potentiated by the induction of DIF-I. The activity in the extracts appeared in an inducible manner after addition of dimethyl sulfoxide or hexamethylenebis(acetamide), reached a maximum at 6 hr, and then rapidly decreased. The induction was inhibited by phorbol 12-myristate 13-acetate and also by cycloheximide. No induction was observed in a mutant MEL cell line defective in erythroid differentiation. These characteristics are consistent with the supposition that DIF-II is one of the putative dimethyl sulfoxide-inducible factors detected in previously reported cell-fusion and cytoplast-fusion experiments. The role of DIF-II in MEL-cell differentiation and in vitro differentiation in general is discussed

Post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin

International Nuclear Information System (INIS)

Yap, A.U.J.

1997-01-01

This study examined the post-irradiation hardness of resin-modified glass ionomer cements and a polyacid-modified composite resin using a digital microhardness tester. Change in hardness of these materials over a period of 6 months was compared to that of conventional glass ionomer cements and a composite resin. With the exception of the composite resin, all materials showed a significant increase in hardness over 24 h after their initial set. Dual-cure resin-modified glass ionomer cements showed decreased hardness with increased storage time in saline at 37 o C. Results suggest that the addition of resins to glass ionomer cements does not improve initial hardness and does not negate the acid-base reaction of conventional cements. Resin addition may, however, lead to increased water sorption and decreased hardness. (author)

Thermal cycling effects on adhesion of resin-bovine enamel junction among different composite resins.

Science.gov (United States)

Chen, Wen-Cheng; Ko, Chia-Ling; Wu, Hui-Yu; Lai, Pei-Ling; Shih, Chi-Jen

2014-10-01

Thermal cycling is used to mimic the changes in oral cavity temperature experienced by composite resins when used clinically. The purpose of this study is to assess the thermal cycling effects of in-house produced composite resin on bonding strength. The dicalcium phosphate anhydrous filler surfaces are modified using nanocrystals and silanization (w/NP/Si). The resin is compared with commercially available composite resins Filtek Z250, Z350, and glass ionomer restorative material GIC Fuji-II LC (control). Different composite resins were filled into the dental enamel of bovine teeth. The bond force and resin-enamel junction graphical structures of the samples were determined after thermal cycling between 5 and 55°C in deionized water for 600 cycles. After thermal cycling, the w/NP/Si 30wt%, 50wt% and Filtek Z250, Z350 groups showed higher shear forces than glass ionomer GIC, and w/NP/Si 50wt% had the highest shear force. Through SEM observations, more of the fillings with w/NP/Si 30wt% and w/NP/Si 50wt% groups flowed into the enamel tubule, forming closed tubules with the composite resins. The push-out force is proportional to the resin flow depth and uniformity. The push-out tubule pore and resin shear pattern is the most uniform and consistent in the w/NP/Si 50wt% group. Accordingly, this developed composite resin maintains great mechanical properties after thermal cycling. Thus, it has the potential to be used in a clinical setting when restoring non-carious cervical lesions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Resin composites

DEFF Research Database (Denmark)

Benetti, Ana Raquel; Peutzfeldt, Anne; Lussi, Adrian

2014-01-01

OBJECTIVE: To investigate how the modulus of elasticity of resin composites influences marginal quality in restorations submitted to thermocyclic and mechanical loading. METHODS: Charisma, Filtek Supreme XTE and Grandio were selected as they were found to possess different moduli of elasticity...... of resin composite (p=0.81) on the quality of dentine margins was observed, before or after loading. Deterioration of all margins was evident after loading (p....008). CONCLUSIONS: The resin composite with the highest modulus of elasticity resulted in the highest number of gap-free enamel margins but with an increased incidence of paramarginal enamel fractures. CLINICAL SIGNIFICANCE: The results from this study suggest that the marginal quality of restorations can...

Solubility of mixed monomers of tetrafluoroethylene and propylene in water and latex

International Nuclear Information System (INIS)

Watanabe, Hiromasa; Okamoto, Jiro

1978-03-01

For kinetical analysis of the emulsion copolymerization of tetrafluoroethylene with propylene and selection of the optimum reaction conditions, the monomer concentrations and composition of the polymer particle were measured and the relations with reaction conditions were determined. Solubilities of tetrafluoroethylene and propylene in water increase with pressure. solubility of propylene is larger than that of tetrafluoroethylene. Solubility of the mixed monomers in water and latex increases with pressure and propylene concentration and decreases with temperature. Propylene concentration in the dissolved monomers is dependent on its concentration in the gas phase and independent of pressure and temperature. The monomer concentrations and the composition were estimated from measurements. Under propylene concentration in the gas phase of 0 to 40 wt % at 30 Kg/cm 2 G and 40 0 C, the monomer concentration and propylene fraction of the polymer particle are 17 -- 27% and 0 -- 62% respectively. The amount of propylene in the particle increases with its fraction in the gas phase, but the amount of tetrafluoroethylene is independent of its fraction in the gas phase. Monomer composition of the polymer particle is dependent on monomer composition of the gas phase and independent of temperature and pressure. The concentration in the polymer particle is 17% at propylene concentration 10 mole % in the gas phase. (auth.)

Thermodynamics of swelling of latex particles with two monomers: a sensitivity analysis

NARCIS (Netherlands)

Maxwell, I.A.; Noel, E.F.J.; Schoonbrood, H.A.S.; German, A.L.

1993-01-01

A sensitivity anal. is performed to det. at what conditions the simplified model for swelling of latex particles by two monomers or two solvents is valid. This model proposes that, inter alia, the fractions of two monomers in the latex particles and in the monomer droplets are equal. The model is a

Diffusion through composite materials made with thermosetting resins

International Nuclear Information System (INIS)

Morin, Bruno.

1981-08-01

Medium and low-level radioactive wastes may be coated in a solid matrix mainly made with thermosetting resins: the study of water and cesium migration through composite materials made with thermosetting resins is usefull to compare the water tightness of different coatings. Disks with a thickness of two millimeters were used to measure the water absorption. Diffusion cells including a plane membrane the thickness of which was at least 70μ were used to measure the diffusion of cesium 137. The diffusion coefficient of water in pure thermosetting resins, polyester or epoxyde, is about 10 -9 cm 2 .s -1 ; the diffusion coefficients of cesium in the same materials are about 10 -12 cm 2 .s -1 ; the introduction of solid particles in these polymers generally induces an acceleration of the diffusion process: the diffusion coefficient may reach 10 -8 cm 2 .s -1 . This lost of water-tightness may be reduced either by rendering insoluble the filler mixed to the polymer, or by diminushing the porosity of the interfacial zones by improving the bonding between the polymer and the filler [fr

Gastroprotective effect of the Mapuche crude drug Araucaria araucana resin and its main constituents.

Science.gov (United States)

Schmeda-Hirschmann, Guillermo; Astudillo, Luis; Rodríguez, Jaime; Theoduloz, Cristina; Yáñez, Tania

2005-10-03

The resin from the tree Araucaria araucana (Araucariaceae) has been used since pre-columbian times by the Mapuche amerindians to treat ulcers. The gastroprotective effect of the resin was assessed in the ethanol-HCl-induced gastric ulcer in mice showing a dose-dependent gastroprotective activity at 100, 200 and 300 mg/kg per os. The main three diterpene constituents of the resin, namely imbricatolic acid, 15-hydroxyimbricatolal and 15-acetoxyimbricatolic acid were isolated and evaluated for gastroprotective effect at doses of 50, 100 and 200 mg/kg. A dose-related gastroprotective effect with highly significant activity (PMapuche culture.

Comparison of Mechanical Properties of Resin Composites with Resin Modified Glass Ionomers

Directory of Open Access Journals (Sweden)

Taha NA

2015-06-01

Full Text Available Statement of Problem: There are controversial reports regarding physical and mechanical properties of resin composites and glass ionomer cements. Some revealed higher strength and hardness for resin composites while others showed a comparable value for glass ionomer cements. Evaluation of mechanical properties of different types of resin composites in comparison with resin modified glass ionomers is not widely studied. Objectives: To measure and compare the flexural strength and Vickers hardness of three resin composites and two resins modified glass ionomer cements before and after ageing. Materials and Methods: Three resin composites, i.e. Filtek Supreme XTE (3M ESPE, Ice (SDI, Gradia (GC, and two resins modified glass ionomers, i.e. Fuji II LC (GC and Riva Light Cure (SDI, were selected. Ten barshaped specimens were prepared for each material and cured using LED curing light. After 24 hours storage in distilled water at 37oC, the specimens were randomly divided into two equal groups (n=5. The first group was tested as a baseline and the second group was restored at 37oC for another 29 days. Flexural strength was performed by four-point bending test using universal testing machine at crosshead speed of 0.5mm/min, and the maximum load at failure was recorded. The specimen’s halves were used for evaluating Vickers hardness, using a Digital Hardness Tester (300 g/15 sec and the Vickers hardness number (VHN was recorded. Data were analyzed using one-way analysis of variance (ANOVA, Tukey’s and student’s t-test. Results: After 24 hours of immersion, the highest hardness number was found for Filtek Supreme and Ice and the highest flexural strength was obtained for Gradia. After 30 days of storage, hardness of Fuji II LC and Gradia showed a significant decrease; flexural strength of Ice and Fuji II LC revealed a significant increase while Gradia and Filtek Supreme showed a significant decrease. Conclusions: Resin modified glass ionomers showed

CHARACTERIZATION OF ALKALINE LIGNINS FOR USE IN PHENOL-FORMALDEHYDE AND EPOXY RESINS

Directory of Open Access Journals (Sweden)

Nour Eddine El Mansouri

2011-05-01

Full Text Available Besides polyurethanes and polyesters, phenolic and epoxy resins are the most prominent applications for technical lignins in thermosetting materials. To evaluate the potential application of lignin raw materials in phenol formaldehyde and epoxy resins, three types of alkaline lignins were characterized in terms of their structures and thermal properties. The lignin samples analyzed were kraft lignin (LIG-1, soda–rice straw lignin (LIG-2, and soda-wheat straw lignin (LIG-3. FTIR and 1H-NMR methods were used to determine their structure. Gel permeation chromatography (GPC was used to determine the molecular weight distribution (MWD. Differential scanning calorimetry (DSC was used to measure the glass transition temperature (Tg, and thermogravimetric analysis (TGA to determine the thermal stability of lignin samples. Results showed that kraft lignin (LIG-1 has moderate hydroxyl-group content, is rich in G-type units, and has good thermal stability. These properties make it more suitable for direct use in phenol formaldehyde resins, and it is therefore a good raw material for this purpose. The alkaline soda-rice straw lignin (LIG-2 with a high hydroxyl-group content and excellent thermal stability is most suited to preparing lignin-based epoxy resins.

Method of solidifying radioactive laundry wastes

International Nuclear Information System (INIS)

Yasumura, Keijiro

1984-01-01

Purpose: To enable to solidify radioactive laundry wastes containing non-ionic liquid detergents less solidifiable by plastic solidification process in liquid laundry wastes for cloths or the likes discharged from a nuclear power plant. Method: Radioactive laundry wastes are solidified by using plastic solidifying agent comprising, as a main ingredient, unsaturated polyester resins and methylmethacrylate monomers. The plastic solidifying agents usable herein include, for example, unsaturated polyester resins prepared by condensating maleic anhydride and phthalic anhydride with propylene glycol and incorporated with methylmethacrylate monomers. The mixing ratio of the methylmethacrylate monomers is preferably 30 % by weight based on the unsaturated polyester resins. (Aizawa, K.)

Metformin induces differentiation in acute promyelocytic leukemia by activating the MEK/ERK signaling pathway

International Nuclear Information System (INIS)

Huai, Lei; Wang, Cuicui; Zhang, Cuiping; Li, Qihui; Chen, Yirui; Jia, Yujiao; Li, Yan; Xing, Haiyan; Tian, Zheng; Rao, Qing; Wang, Min; Wang, Jianxiang

2012-01-01

Highlights: ► Metformin induces differentiation in NB4 and primary APL cells. ► Metformin induces activation of the MEK/ERK signaling pathway in APL cells. ► Metformin synergizes with ATRA to trigger maturation of NB4 and primary APL cells. ► Metformin induces the relocalization and degradation of the PML-RARα fusion protein. ► The study may be applicable for new differentiation therapy in cancer treatment. -- Abstract: Recent studies have shown that metformin, a widely used antidiabetic agent, may reduce the risk of cancer development. In this study, we investigated the antitumoral effect of metformin on both acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL) cells. Metformin induced apoptosis with partial differentiation in an APL cell line, NB4, but only displayed a proapoptotic effect on several non-M3 AML cell lines. Further analysis revealed that a strong synergistic effect existed between metformin and all-trans retinoic acid (ATRA) during APL cell maturation and that metformin induced the hyperphosphorylation of extracellular signal-regulated kinase (ERK) in APL cells. U0126, a specific MEK/ERK activation inhibitor, abrogated metformin-induced differentiation. Finally, we found that metformin induced the degradation of the oncoproteins PML-RARα and c-Myc and activated caspase-3. In conclusion, these results suggest that metformin treatment may contribute to the enhancement of ATRA-induced differentiation in APL, which may deepen the understanding of APL maturation and thus provide insight for new therapy strategies.

The mechanism of uranium adsorption on Resin 508 and isoelectric point of the resin

International Nuclear Information System (INIS)

Han Qingping; Lu Weichang; Su Huijuan; Hu Jinbo; Zhang Liqin; Chen Banglin

1990-01-01

The adsorption process of uranium by Resin 508 at the solid-liquid interface was investigated and the mechanism of uranium adsorption including adsorption dynamics, adsorption thermodynamics and isoelectric point of resin was studied. The results are as follows: The maximum of uranium adsorption is attained at pH5-7; Uranium adsorption isotherm by Resin 508 in experimental conditions agrees with Langmuir's adsorption isotherm, the maximum of uranium adsorbed (Vm) is 716 mg U/g-dried resin; The adsorption of uranium by Resin 508 is an endothermic reaction and ΔH = 16.87 kJ/mol; The exchange-adsorption rate is mainly controlled by liquid film diffusion; The isoelectric points of Resin 508 before and after uranium adsorption are found to be pH7.5 and pH5.7 respectively. It is a specific adsorption for uranium

Avaliação de monômero residual em resinas acrílicas de uso ortodôntico e protético: análise por espectroscopia Evaluation of residual monomer in autopolymerizing acrylic resins: spectroscopy analysis

Directory of Open Access Journals (Sweden)

Roberto Rocha Filho

2007-04-01

Full Text Available OBJETIVO: duas marcas comerciais de resinas acrílicas ativadas quimicamente (RAAQ, uma de uso ortodôntico (Orto Cril® e outra de uso protético (Jet®, polimerizadas em presença e ausência de pressão, foram analisadas em relação ao conteúdo de monômero (MMA residual liberado em solução, em diferentes intervalos de tempo (0,083; 0,25; 1; 1,25; 2,17; 5; 9; 14 e 21 dias. METODOLOGIA: a espectroscopia de absorção no ultravioleta foi utilizada na análise de soluções aquosas de MMA, com concentrações conhecidas, visando a determinação de uma curva de calibração. Soluções aquosas contendo corpos-de-prova, confeccionados com as citadas RAAQ, foram também submetidas à análise por espectroscopia de absorção no ultravioleta. RESULTADOS E CONCLUSÕES: os resultados foram comparados aos dados da curva de calibração, visando estabelecer a concentração de MMA residual das amostras. Eles permitiram concluir que o nível de MMA residual liberado em solução foi mais elevado durante as primeiras 24 horas, havendo uma tendência à estabilização a partir desse período e que a resina acrílica de uso ortodôntico apresentou níveis mais elevados de MMA em solução do que a de uso protético, em ambas as condições de polimerização empregadas, com presença e ausência de pressão. Além disso, a presença de pressão, durante a polimerização das duas resinas, elevou a concentração de MMA em solução, não havendo, entretanto, efeito da interação entre as marcas das resinas e a presença e ausência de pressão na concentração de MMA em solução, medida ao longo do tempo. Porém, todas as três variáveis (tempo, resina e pressão foram significantes.AIM: Two comercial brands of auto polymerizing acrylic resins (one for orthodontics use, Orto Cril®, and the other for prosthetics use, Jet® were analyzed concerning the amount of methyl methacrilate (MMA monomer dissolved in solution, processed under and not under

Bond durability of adhesives containing modified-monomer with/without-fluoride after aging in artificial saliva and under intrapulpal pressure simulation.

Science.gov (United States)

El-Deeb, H A; Al Sherbiney, H H; Mobarak, E H

2013-01-01

To evaluate the dentin bond strength durability of adhesives containing modified-monomer with/without-fluoride after storage in artificial saliva and under intrapulpal pressure simulation (IPPS). The occlusal enamel of 48 freshly extracted teeth was trimmed to expose midcoronal dentin. Roots were sectioned to expose the pulp chamber and to connect the specimens to the pulpal-pressure assembly. Specimens were assigned into four groups (n=12) according to adhesive system utilized: a two-step etch-and-rinse adhesive system (SB, Adper Single Bond 2, 3M ESPE), a two-step self-etch adhesive system (CSE, Clearfil SE Bond, Kuraray Medical Inc), and two single-step self-etch adhesives with the same modified monomer (bis-acrylamide)-one with fluoride (AOF, AdheSE One F, Ivoclar-Vivadent) and the other without (AO, AdheSE One, Ivoclar-Vivadent). Bonding was carried out while the specimens were subjected to 15-mm Hg IPPS. Resin composite (Valux Plus, 3M ESPE) buildups were made. After curing, specimens were aged in artificial saliva and under 20-mm Hg IPPS at 37°C in a specially constructed incubator either for 24 hours or six months prior to testing. Bonded specimens (n=6/group) were sectioned into sticks (n=24/group) with a cross section of 0.9 ± 0.01 mm(2) and subjected to microtensile bond strength (μTBS) testing using a universal testing machine. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA tests, and a t-test (partificial saliva and under IPPS, yet these values remained significantly higher than those for the other two adhesives with modified monomers. There was no significant difference in the bond strength values between fluoride-containing and fluoride-free self-etch adhesive systems (AOF and AO) after 24 hours or six months. Modes of failure were mainly adhesive and mixed. Based on the results of this study, 1) Fluoride addition did not affect dentin bond durability; and 2) despite the fact that

Electron-beam curing of epoxy resins: effect of alcohols on cationic ...

Indian Academy of Sciences (India)

Unknown

Electron-beam (e-beam) induced polymerization of epoxy resins proceeds via cationic mechanism in presence of suitable ... generate ionic species, free radicals, and/or molecules in .... bisphenol A) and the effect of presence of different OH.

Evaluation of level of impregnation monomers in hydrotalcite

International Nuclear Information System (INIS)

Carmo, Danieli M. do; Machado, Jacson S.C.; Oliveira, Marcelo F.L.; Oliveira, Marcia G.; Soares, Bluma G.

2011-01-01

To evaluate the impregnation degree of 1,6-hexamethylene diisocyanate and 1,4-butanediol monomers in hydrotalcite clays it was prepared dispersions with mixing ratio 1:100 (clay/monomer), using the Ultraturrax and Ultrasound. Subsequently the samples were characterized by Fourier Transform Infrared Spectroscopy and X-ray Diffraction. Swelling tests and Tyndall effect were used to illustrate the different dispersions. The results indicated a strong interaction between the hydrotalcite with 1,6-hexamethylene diisocyanate, favoring the formation of intercalated structures. (author)

Resin regenerating device in condensate desalting system

International Nuclear Information System (INIS)

Sato, Yoshiaki; Igarashi, Hiroo; Oosumi, Katsumi; Nishimura, Yusaku; Ebara, Katsuya; Shindo, Norikazu.

1984-01-01

Purpose: To improve the accuracy in the separation of anionic and cationic exchange resins. Constitution: Resins transferred from a condensate desalting column are charged in a cationic exchange resin column. The temperature of water for separating and transferring the resins is measured by a temperature detector disposed in a purified water injection line, and water is adjusted to a suitable flow rate for the separation and transfer of the resins by an automatic flow rate control valve, and then is injected. The resins are separated into cationic exchange resins and anionic exchange resins, in which only the anionic exchange resins are transferred, through an anionic exchange transfer line, into an anionic exchange resin column. By controlling the flow rate depending on the temperature of the injected water, the developing rate of the resin layer is made constant to enable separation and transfer of the resins at high accuracy. (Seki, T.)

Characteristics of floc formation of anion and cation exchange resin in precoat filter using powdered ion exchange resin

International Nuclear Information System (INIS)

Adachi, Tetsurou; Sawa, Toshio; Shindoh, Toshikazu.

1989-01-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of floc formation. The physical, chemical and electrochemical properties of powdered ion exchange resin were measured and the factors related to floc formation of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index. It was found that these factors were mixing ratio, nature of resins and particle size of resins. In addition, it was assumed on the bases of these results that the amount of resin floc was related to sum of the surface electric charges of both resins. The filling ratio of resin floc was related to their product by multiplication and an experimental expression was obtained. The specific settle volume of resin floc could then be simulated by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author)

Characteristics of floc formation of anion and cation exchange resin in precoat filter using powdered ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

Adachi, Tetsurou (Nitto Denko Corp., Ibaraki, Osaka (Japan)); Sawa, Toshio; Shindoh, Toshikazu

1989-09-01

The filtration performance of mixed filter aid consisting of powdered anion and cation exchange resins used in the precoat filter is closely related to the characteristics of floc formation. The physical, chemical and electrochemical properties of powdered ion exchange resin were measured and the factors related to floc formation of anion and cation exchange resin were investigated by measuring the specific settle volume of resin floc as an evaluating index. It was found that these factors were mixing ratio, nature of resins and particle size of resins. In addition, it was assumed on the bases of these results that the amount of resin floc was related to sum of the surface electric charges of both resins. The filling ratio of resin floc was related to their product by multiplication and an experimental expression was obtained. The specific settle volume of resin floc could then be simulated by particle size, surface area, ion exchange capacity and degree of ionization of the powdered ion exchange resin. (author).

Solidification of ion exchange resins saturated with Na+ ions: Comparison of matrices based on Portland and blast furnace slag cement

International Nuclear Information System (INIS)

Lafond, E.; Cau dit Coumes, C.; Gauffinet, S.; Chartier, D.; Stefan, L.; Le Bescop, P.

2017-01-01

This work is devoted to the conditioning of ion exchange resins used to decontaminate radioactive effluents. Calcium silicate cements may have a good potential to encapsulate spent resins. However, certain combinations of cement and resins produce a strong expansion of the final product, possibly leading to its full disintegration. The focus is placed on the understanding of the behaviour of cationic resins in the Na + form in Portland or blast furnace slag (CEM III/C) cement pastes. During hydration of the Portland cement paste, the pore solution exhibits a decrease in its osmotic pressure, which causes a transient expansion of small magnitude of the resins. At 20 °C, this expansion takes place just after setting in a poorly consolidated material and is sufficient to induce cracks. In the CEM III/C paste, swelling of the resins also occurs, but before the end of setting, and induces limited stress in the matrix which is still plastic. - Highlights: • Solidification of cationic resins in the Na + -form is investigated. • Portland and blast furnace slag cements are compared. • Deleterious expansion is observed with Portland cement only. • Resin swelling is due to a decrease in the osmotic pressure of the pore solution. • The consolidation rate of the matrix is a key parameter to prevent damage.

The Off-rate of Monomers Dissociating from Amyloid-β Protofibrils*

Science.gov (United States)

Grüning, Clara S. R.; Klinker, Stefan; Wolff, Martin; Schneider, Mario; Toksöz, Küpra; Klein, Antonia N.; Nagel-Steger, Luitgard; Willbold, Dieter; Hoyer, Wolfgang

2013-01-01

The interconversion of monomers, oligomers, and amyloid fibrils of the amyloid-β peptide (Aβ) has been implicated in the pathogenesis of Alzheimer disease. The determination of the kinetics of the individual association and dissociation reactions is hampered by the fact that forward and reverse reactions to/from different aggregation states occur simultaneously. Here, we report the kinetics of dissociation of Aβ monomers from protofibrils, prefibrillar high molecular weight oligomers previously shown to possess pronounced neurotoxicity. An engineered binding protein sequestering specifically monomeric Aβ was employed to follow protofibril dissociation by tryptophan fluorescence, precluding confounding effects of reverse or competing reactions. Aβ protofibril dissociation into monomers follows exponential decay kinetics with a time constant of ∼2 h at 25 °C and an activation energy of 80 kJ/mol, values typical for high affinity biomolecular interactions. This study demonstrates the high kinetic stability of Aβ protofibrils toward dissociation into monomers and supports the delineation of the Aβ folding and assembly energy landscape. PMID:24247242

Step growth of an AB2 monomer, with cycle formation

DEFF Research Database (Denmark)

Cameron, Colin; Fawcett, Allan H.; Hetherington, Cecil R.

1998-01-01

A computer-based lattice model of the step growth reaction of an AB2 monomer, the next elaborate system after an AB monomer, has been devised that allows the simultaneous and explicit occurrence of inter- and intramolecular reactions of A and B groups of the flexible and moving molecules according...... with fractal characteristics. Growth stops when each molecule contains a cycle. For the model explored, in which six lattice sites are used for each monomer, the limiting value of the number average degree of polymerization, 〈x〉n,∞, is 14.6(±0.3) (after infinite time). The occurrence within the system of rings...... of m residues (m=1,2,3,...) is found to depend upon m and the extent of reaction of the A groups, pa, according to Rm=C0pm am-2.71, the constant C0 reflecting the structure of the lattice and the monomer, and being shown to determine the final degree of polymerization. The exponent of the integers m...

Characterization of dimethacrylate polymeric networks: a study of the crosslinked structure formed by monomers used in dental composites.

Science.gov (United States)

Pfeifer, Carmem S; Shelton, Zachary R; Braga, Roberto R; Windmoller, Dario; Machado, José C; Stansbury, Jeffrey W

2011-02-01

The resin phase of dental composites is mainly composed of combinations of dimethacrylate comonomers, with final polymeric network structure defined by monomer type/reactivity and degree of conversion. This fundamental study evaluates how increasing concentrations of the flexible triethylene glycol dimethacrylate (TEGDMA) influences void formation in bisphenol A diglycidyl dimethacrylate (BisGMA) co-polymerizations and correlates this aspect of network structure with reaction kinetic parameters and macroscopic volumetric shrinkage. Photopolymerization kinetics was followed in real-time by a near-infrared (NIR) spectroscopic technique, viscosity was assessed with a viscometer, volumetric shrinkage was followed with a linometer, free volume formation was determined by positron annihilation lifetime spectroscopy (PALS) and the sol-gel composition was determined by extraction with dichloromethane followed by (1)H-NMR analysis. Results show that, as expected, volumetric shrinkage increases with TEGDMA concentration and monomer conversion. Extraction/(1)H-NMR studies show increasing participation of the more flexible TEGDMA towards the limiting stages of conversion/crosslinking development. As the conversion progresses, either based on longer irradiation times or greater TEGDMA concentrations, the network becomes more dense, which is evidenced by the decrease in free volume and weight loss after extraction in these situations. For the same composition (BisGMA/TEGDMA 60-40 mol%) light-cured for increasing periods of time (from 10 to 600 s), free volume decreased and volumetric shrinkage increased, in a linear relationship with conversion. However, the correlation between free volume and macroscopic volumetric shrinkage was shown to be rather complex for variable compositions exposed for the same time (600 s). The addition of TEGDMA decreases free-volume up to 40 mol% (due to increased conversion), but above that concentration, in spite of the increase in conversion

Acid monomer analysis in waterborne polymer systems by targeted labeling of carboxylic acid functionality, followed by pyrolysis - gas chromatography.

Science.gov (United States)

Brooijmans, T; Okhuijsen, R; Oerlemans, I; Schoenmakers, P J; Peters, R

2018-05-14

Pyrolysis - gas chromatography - (PyGC) is a common method to analyse the composition of natural and synthetic resins. The analysis of acid functionality in, for example, waterborne polyacrylates and polyurethanes polymers has proven to be difficult due to solubility issues, inter- and intramolecular interaction effects, lack of detectability in chromatographic analysis, and lack of thermal stability. Conventional analytical techniques, such as PyGC, cannot be used for the direct detection and identification of acidic monomers, due to thermal rearrangements that take place during pyrolysis. To circumvent this, the carboxylic acid groups are protected prior to thermal treatment by reaction with 2-bromoacetophenone. Reaction conditions are investigated and optimised wrt. conversion measurements. The aproach is applied to waterborne polyacryalates and the results are discussed. This approach enables identification and (semi)quantitative analysis of different acid functionalities in waterborne polymers by PyGC. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis, characterization and thermal analysis of urea-formaldehyde/nanoSiO{sub 2} resins

Energy Technology Data Exchange (ETDEWEB)

Roumeli, E. [Solid State Physics Dept., School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Papadopoulou, E. [Chimar Hellas S.A., Sofouli 88, 55131 Thessaloniki (Greece); Pavlidou, E.; Vourlias, G. [Solid State Physics Dept., School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Bikiaris, D. [Department of Chemistry, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Paraskevopoulos, K.M. [Solid State Physics Dept., School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Chrissafis, K., E-mail: hrisafis@physics.auth.gr [Solid State Physics Dept., School of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

2012-01-10

Highlights: Black-Right-Pointing-Pointer UF/nanosilica resins have been produced using the minimum cost method. Black-Right-Pointing-Pointer The new resins had good dispersion and enhanced properties. Black-Right-Pointing-Pointer Nanosilica interacts with polymer chains as was proved by FTIR and DSC. Black-Right-Pointing-Pointer Nanosilica does not affect the resin's thermal stability but enhances its mechanical properties. - Abstract: In the present work urea-formaldehyde resins (UF) containing different amounts of SiO{sub 2} nanoparticles were synthesized and studied in depth. All the hybrids were characterized with Fourier transform infrared spectroscopy (FTIR) and powder X-ray diffractometry (XRD), while the dispersion of nanoparticles was studied with scanning electron microscopy with associated energy dispersive X-ray spectrometer (SEM/EDS). It was found that even though silanol groups of SiO{sub 2} can interact with UF resin and form hydrogen bonds, aggregates of SiO{sub 2} nanoparticles can still be formed in UF resin. Their size increases as SiO{sub 2} content is increased. The curing reactions were examined with differential scanning calorimetry (DSC) and it was revealed that curing temperature of UF resin is slightly affected by the addition of nanoparticles. Furthermore, the activation energy of the curing reactions, for every hybrid, was calculated using the Kissinger's method, which implied the existence of interactions between the nanoparticles and the polymer chain. Thermogravimetric analysis (TGA) revealed that SiO{sub 2} nanoparticles do not have an effect in the thermal stability of the resin. From the application of the prepared UF/SiO{sub 2} resins in wood panels it was found that the mechanical properties of the panels, like the internal bond and the modulus of rapture, are enhanced with increasing nanoSiO{sub 2} concentration.

Gene expression change in human dental pulp cells exposed to a low-level toxic concentration of triethylene glycol dimethacrylate: an RNA-seq analysis.

Science.gov (United States)

Cho, Sung-Geun; Lee, Jin-Woo; Heo, Jung Sun; Kim, Sun-Young

2014-09-01

Dental composite resin restoration for defective tooth may lead unpolymerized resin monomers to be leached into dental pulp tissue. The aim of this study was to investigate the early gene expression change over time of human dental pulp cells (HDPCs) treated with a low-level toxic concentration of Triethylene Glycol Dimethacrylate (TEGDMA), a common dental resin monomer, by adopting the novel high-throughput transcriptome analysis of RNA-seq. The low-level toxic concentration of TEGDMA was determined through MTT assays with serially diluted concentrations. After the HDPCs were exposed to TEGDMA for 6, 12, 24 or 48 hr, the total RNA of the samples was prepared for RNA-seq. qRT-PCR for several genes was performed for validation of RNA-seq results. In the treated group, 1280 genes were differentially expressed compared with the control group. Five patterns of time-series gene expression profiles were identified through k-means clustering analysis. Angiogenesis, cell adhesion and migration, extracellular matrix organization, response to extracellular stimulus, inflammatory response and mineralization-related process were major gene ontology terms in functional annotation clustering. HMOX1, OSGIN1, SMN2, SRXN1 AKR1C1, SPP1 and TOMM40L were highly up-regulated genes, and WRAP53 and CCL2 were highly down-regulated genes over time. qRT-PCR for several genes exhibited a high level of agreement with RNA-seq. TEGDMA induced the HDPCs to show massive and dynamic gene expression changes over time. The previously suggested toxic mechanism of TEGDMA was not only verified, but new genes whose functions have yet to be determined were also found. © 2014 Nordic Association for the Publication of BCPT (former Nordic Pharmacological Society).

46 CFR 151.50-34 - Vinyl chloride (vinyl chloride monomer).

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Vinyl chloride (vinyl chloride monomer). 151.50-34... chloride (vinyl chloride monomer). (a) Copper, aluminum, magnesium, mercury, silver, and their alloys shall... equipment that may come in contact with vinyl chloride liquid or vapor. (b) Valves, flanges, and pipe...

EDF specifications on nuclear grade resins

International Nuclear Information System (INIS)

Mascarenhas, Darren; Gressier, Frederic; Taunier, Stephane; Le-Calvar, Marc; Ranchoux, Gilles; Marteau, Herve; Labed, Veronique

2012-09-01

Ion exchange resins are widely used across EDF, especially within the nuclear division for the purification of water. Important applications include primary circuit, secondary circuit and effluent treatment, which require high quality nuclear grade resins to retain the dissolved species, some of which may be radioactive. There is a need for more and more efficient purification in order to decrease worker dose during maintenance but also to decrease volumes of radioactive resin waste. Resin performance is subject to several forms of degradation, including physical, chemical, thermal and radioactive, therefore appropriate resin properties have to be selected to reduce such effects. Work has been done with research institutes, manufacturers and on EDF sites to select these properties, create specifications and to continuously improve on these specifications. An interesting example of research regarding resin performance is the resin degradation under irradiation. Resins used in the CVCS circuit of EDF nuclear power plants are subject to irradiation over their lifetime. A study was carried out on the effects of total integrated doses of 0.1, 1 and 10 MGy on typically used EDF mixed bed resins in a 'mini-CVCS' apparatus to simultaneously test actual primary circuit fluid. The tests confirmed that the resins still perform efficiently after a typical CVCS radiation dose. Certain resins also need additional specifications in order to maintain the integrity of the particular circuits they are used in. Recently, EDF has updated its requirements on these high purity nuclear grade resins, produced generic doctrines for all products and materials used on site which include resins of all grades, and as a result have also updated a guide on recommended resin usage for the French fleet of reactors. An overview of the evolutions will be presented. (authors)

Radiation-Induced Graft Polymerization of Vinyl Monomers with Anion Groups onto MWNT Supports and Their Application as Electrogenerated Chemiluminescence (ECL Biosensors

Directory of Open Access Journals (Sweden)

Ji-Hye Park

2014-01-01

Full Text Available Vinyl polymer-grafted multiwalled carbon nanotube (MWNT supports with anion groups were prepared for use as biosensor supports by radiation-induced graft polymerization (RIGP of the vinyl monomers acryloyl diphosphoric acid (ADPA, acrylic acid (AA, sodium styrenesulfonate (NaSS, and methacrylic acid (MA onto the surface of MWNTs. The electrogenerated chemiluminescence sensors based on a glass carbon electrode (ECL-GCE and a screen printed electrode (ECL-SPE were fabricated by immobilization of Ru(bpy3 2+ complex after coating of vinyl polymer-grafted MWNT inks on the surface of the GCE and SPE without any polymer binders in order to obtain high electrogenerated chemiluminescence intensity. For detection of alcohol concentration, alcohol dehydrogenase (ADH was immobilized onto an ECL-GCE sensor prepared by poly(NaSS-g-MWNT supports. The prepared biosensor based on ADH is suitable for the detection of ethanol concentration in commercial drinks.

Chemical Characterization of Beer Aging Products Derived from Hard Resin Components in Hops (Humulus lupulus L.).

Science.gov (United States)

Taniguchi, Yoshimasa; Yamada, Makiko; Taniguchi, Harumi; Matsukura, Yasuko; Shindo, Kazutoshi

2015-11-25

The bitter taste of beer originates from resins in hops (Humulus lupulus L.), which are classified into two subtypes (soft and hard). Whereas the nature and reactivity of soft-resin-derived compounds, such as α-, β-, and iso-α-acids, are well studied, there is only a little information on the compounds in hard resin. For this work, hard resin was prepared from stored hops and investigated for its compositional changes in an experimental model of beer aging. The hard resin contained a series of α-acid oxides. Among them, 4'-hydroxyallohumulinones were unstable under beer storage conditions, and their transformation induced primary compositional changes of the hard resin during beer aging. The chemical structures of the products, including novel polycyclic compounds scorpiohumulinols A and B and dicyclohumulinols A and B, were determined by HRMS and NMR analyses. These compounds were proposed to be produced via proton-catalyzed cyclization reactions of 4'-hydroxyallohumulinones. Furthermore, they were more stable than their precursor 4'-hydroxyallohumulinones during prolonged storage periods.

System for removing contaminants from plastic resin

Science.gov (United States)

Bohnert, George W.; Hand, Thomas E.; DeLaurentiis, Gary M.

2010-11-23

A resin recycling system that produces essentially contaminant-free synthetic resin material in an environmentally safe and economical manner. The system includes receiving the resin in container form. A grinder grinds the containers into resin particles. The particles are exposed to a solvent in one or more solvent wash vessels, the solvent contacting the resin particles and substantially removing contaminants on the resin particles. A separator is used to separate the resin particles and the solvent. The resin particles are then placed in solvent removing element where they are exposed to a solvent removing agent which removes any residual solvent remaining on the resin particles after separation.

Metformin induces differentiation in acute promyelocytic leukemia by activating the MEK/ERK signaling pathway

Energy Technology Data Exchange (ETDEWEB)

Huai, Lei; Wang, Cuicui; Zhang, Cuiping; Li, Qihui; Chen, Yirui; Jia, Yujiao; Li, Yan; Xing, Haiyan; Tian, Zheng; Rao, Qing; Wang, Min [State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300020 (China); Wang, Jianxiang, E-mail: wangjx@ihcams.ac.cn [State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin 300020 (China)

2012-06-08

Highlights: Black-Right-Pointing-Pointer Metformin induces differentiation in NB4 and primary APL cells. Black-Right-Pointing-Pointer Metformin induces activation of the MEK/ERK signaling pathway in APL cells. Black-Right-Pointing-Pointer Metformin synergizes with ATRA to trigger maturation of NB4 and primary APL cells. Black-Right-Pointing-Pointer Metformin induces the relocalization and degradation of the PML-RAR{alpha} fusion protein. Black-Right-Pointing-Pointer The study may be applicable for new differentiation therapy in cancer treatment. -- Abstract: Recent studies have shown that metformin, a widely used antidiabetic agent, may reduce the risk of cancer development. In this study, we investigated the antitumoral effect of metformin on both acute myeloid leukemia (AML) and acute promyelocytic leukemia (APL) cells. Metformin induced apoptosis with partial differentiation in an APL cell line, NB4, but only displayed a proapoptotic effect on several non-M3 AML cell lines. Further analysis revealed that a strong synergistic effect existed between metformin and all-trans retinoic acid (ATRA) during APL cell maturation and that metformin induced the hyperphosphorylation of extracellular signal-regulated kinase (ERK) in APL cells. U0126, a specific MEK/ERK activation inhibitor, abrogated metformin-induced differentiation. Finally, we found that metformin induced the degradation of the oncoproteins PML-RAR{alpha} and c-Myc and activated caspase-3. In conclusion, these results suggest that metformin treatment may contribute to the enhancement of ATRA-induced differentiation in APL, which may deepen the understanding of APL maturation and thus provide insight for new therapy strategies.

Evaluation of fracture toughness and mechanical properties of ternary thiol-ene-methacrylate systems as resin matrix for dental restorative composites.

Science.gov (United States)

Beigi, Saeed; Yeganeh, Hamid; Atai, Mohammad

2013-07-01

Study and evaluation of fracture toughness, flexural and dynamic mechanical properties, and crosslink density of ternary thiol-ene-methacrylate systems and comparison with corresponding conventional methacrylate system were considered in the present study. Urethane tetra allyl ether monomer (UTAE) was synthesized as ene monomer. Different formulations were prepared based on combination of UTAE, BisGMA/TEGDMA and a tetrathiol monomer (PETMP). The photocuring reaction was conducted under visible light using BD/CQ combination as photoinitiator system. Mechanical properties were evaluated via measuring flexural strength, flexural modulus and fracture toughness. Scanning electron microscopy (SEM) was utilized to study the morphology of the fractured specimen's cross section. Viscoelastic properties of the samples were also determined by dynamic mechanical thermal analysis (DMTA). The same study was performed on a conventional methacrylate system. The data were analyzed and compared by ANOVA and Tukey HSD tests (significance level=0.05). The results showed improvement in fracture toughness of the specimens containing thiol-ene moieties. DMTA revealed a lower glass transition temperature and more homogenous structure for thiol-ene containing specimens in comparison to the system containing merely methacrylate monomer. The flexural modulus and flexural strength of the specimens with higher thiol-ene content were lower than the neat methacrylate system. The SEM micrographs of the fractured surface of specimens with higher methacrylate content were smooth and mirror-like (shiny) which represent brittle fracture. The thiol-ene-methacrylate system can be used as resin matrix of dental composites with enhanced fracture toughness in comparison to the methacrylate analogous. Copyright © 2013 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

The use of epoxidised palm oil products (EPOP) for the synthesis of radiation curable resins. II. Ultraviolet (UV) curing of epoxidised RBD palm oil acrylate (EPOLA)

International Nuclear Information System (INIS)

Mohd Hilmi bin Mahmood; Hussin bin Mohd Nor; Hamirin bin Kifli; Masni bin Abdul Ragman; Azman bin Rafei

1991-01-01

Epoxidised RBD palm olein acrylate (EPOLA) and polyurethane acrylate (PUA) prepared at UTN laboratory were used as base polymers or oligomers in the formulations of ultraviolet (UV) curable resins. Mono-, di- and trifunctional monomers were utilized both as crosslinkers as well as for diluents. Curing was done by means of 20 cm wide IST UV machine with the conditions of 8A current and 4m/min conveyor speed. The properties of the cured films were investigated by using pencil hardness tester and gel content analysis

The curing behavior and properties of phthalonitrile resins using ionic liquids as a new class of curing agents

Directory of Open Access Journals (Sweden)

K. Cheng

2017-11-01

Full Text Available Binary blends composed of 1,3-bis (3,4-dicyanophenoxy benzene (3BOCN and ionic liquids (ILs with different molecular structures were prepared. The curing behavior of these 3BOCN/ILs blends were studied by thermogravimetric analysis (TGA, differential scanning calorimetry (DSC and rheological analysis. The study suggested that the blends possessed a wide processing window and the structures of ILs (anion, cation and alkyl chain length at cation had an effect on curing behavior. The 3BOCN/[EPy]BF4 resins were prepared at elevated temperature. IR spectra of the resins showed that there were triazine and isoindoline formed in curing process. The TGA and dynamic mechanical analysis (DMA revealed that the resins have excellent thermal stability together with high storage modulus and high glass transition temperature (Tg. Dielectric properties, long term oxidative aging and water uptake measurements of the resins suggested the IL brought some unique properties to the resins.

Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation

International Nuclear Information System (INIS)

Sato, Chieri; Iwasaki, Tsuyoshi; Kitano, Sachie; Tsunemi, Sachi; Sano, Hajime

2012-01-01

Highlights: ► We investigated the role of S1P signaling for osteoblast differentiation. ► Both S1P and FTY enhanced BMP-2-stimulated osteoblast differentiation by C2C12 cells. ► S1P signaling enhanced BMP-2-stimulated Smad and ERK phosphorylation by C2C12 cells. ► MEK/ERK signaling is a pathway underlying S1P signaling for osteoblast differentiation. -- Abstract: We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P receptor-mediated signaling plays a crucial role for osteoblast differentiation.

[Exercise-induced inspiratory stridor. An important differential diagnosis of exercise-induced asthma].

Science.gov (United States)

Christensen, Pernille; Thomsen, Simon Francis; Rasmussen, Niels; Backer, Vibeke

2007-11-19

Recent studies suggest that exercise-induced inspiratory stridor (EIIS) is an important and often overlooked differential diagnosis of exercise-induced asthma. EIIS is characterised by astma-like symptoms, but differs by inspiratory limitation, fast recovery, and a lack of effect of inhaled bronchodilators. The prevalence of EIIS is reported to be 5-27%, and affects both children and adults. The pathophysiology, the pathogenesis, and the treatment of the condition are not yet clarified. At present, a population-based study is being conducted in order to address these points.

Exploring the potential of high resolution mass spectrometry for the investigation of lignin-derived phenol substitutes in phenolic resin syntheses.

Science.gov (United States)

Dier, Tobias K F; Fleckenstein, Marco; Militz, Holger; Volmer, Dietrich A

2017-05-01

Chemical degradation is an efficient method to obtain bio-oils and other compounds from lignin. Lignin bio-oils are potential substitutes for the phenol component of phenol formaldehyde (PF) resins. Here, we developed an analytical method based on high resolution mass spectrometry that provided structural information for the synthesized lignin-derived resins and supported the prediction of their properties. Different model resins based on typical lignin degradation products were analyzed by electrospray ionization in negative ionization mode. Utilizing enhanced mass defect filter techniques provided detailed structural information of the lignin-based model resins and readily complemented the analytical data from differential scanning calorimetry and thermogravimetric analysis. Relative reactivity and chemical diversity of the phenol substitutes were significant determinants of the outcome of the PF resin synthesis and thus controlled the areas of application of the resulting polymers. Graphical abstract ᅟ.

[Acrylic resin removable partial dentures].

Science.gov (United States)

de Baat, C; Witter, D J; Creugers, N H J

2011-01-01

An acrylic resin removable partial denture is distinguished from other types of removable partial dentures by an all-acrylic resin base which is, in principle, solely supported by the edentulous regions of the tooth arch and in the maxilla also by the hard palate. When compared to the other types of removable partial dentures, the acrylic resin removable partial denture has 3 favourable aspects: the economic aspect, its aesthetic quality and the ease with which it can be extended and adjusted. Disadvantages are an increased risk of caries developing, gingivitis, periodontal disease, denture stomatitis, alveolar bone reduction, tooth migration, triggering of the gag reflex and damage to the acrylic resin base. Present-day indications are ofa temporary or palliative nature or are motivated by economic factors. Special varieties of the acrylic resin removable partial denture are the spoon denture, the flexible denture fabricated of non-rigid acrylic resin, and the two-piece sectional denture. Furthermore, acrylic resin removable partial dentures can be supplied with clasps or reinforced by fibers or metal wires.

Synthesis and characterization of novel organotin carboxylate maleimide monomers and copolymers

Directory of Open Access Journals (Sweden)

2009-06-01

Full Text Available Two novel tributyltin carboxylate maleimide monomers, tributyltin(maleimidoacetate and tributyltin(4-maleimidobenzoate, were synthesized by condensation reaction of maleimidoacetic acid or 4-maleimidobenzoic acid with bis(tributyltin oxide. Copolymerization of these monomers with styrene was carried in dioxane at 70°C using asobisisobutyronitrile as free radical initiator. The structures of monomers and copolymers were confirmed by FT-IR (Fourier Transform Infrared, 1H and 13C NMR (nuclear magnetic resonance spectroscopy and elemental analysis. The copolymers were characterized by solubility and thermal analysis.

Differentiation of eosinophilic leukemia EoL-1 cells into eosinophils induced by histone deacetylase inhibitors.

Science.gov (United States)

Ishihara, Kenji; Takahashi, Aki; Kaneko, Motoko; Sugeno, Hiroki; Hirasawa, Noriyasu; Hong, JangJa; Zee, OkPyo; Ohuchi, Kazuo

2007-03-06

EoL-1 cells differentiate into eosinophils in the presence of n-butyrate, but the mechanism has remained to be elucidated. Because n-butyrate can inhibit histone deacetylases, we hypothesized that the inhibition of histone deacetylases induces the differentiation of EoL-1 cells into eosinophils. In this study, using n-butyrate and two other histone deacetylase inhibitors, apicidin and trichostatin A, we have analyzed the relationship between the inhibition of histone deacetylases and the differentiation into eosinophils in EoL-1 cells. It was demonstrated that apicidin and n-butyrate induced a continuous acetylation of histones H4 and H3, inhibited the proliferation of EoL-1 cells without attenuating the level of FIP1L1-PDGFRA mRNA, and induced the expression of markers for mature eosinophils such as integrin beta7, CCR1, and CCR3 on EoL-1 cells, while trichostatin A evoked a transient acetylation of histones and induced no differentiation into eosinophils. These findings suggest that the continuous inhibition of histone deacetylases in EoL-1 cells induces the differentiation into mature eosinophils.

Process for hardening an alkyd resin composition using ionizing radiation. [electron beams, gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Watanabe, T; Murata, K; Maruyama, T

1969-11-27

In an alkyd resin composition having free hydroxide radicals and containing a conjugated unsaturated fatty acid and/or oil as a component thereof, a process for hardening an alkyd resin composition comprises the steps of dissolving into a vinyl monomer, the product obtained by the semi-esterification reaction of said hydroxide radicals with acid anhydrides having polymerizable radicals and hardening by ionizing radiation to provide a coating with a high degree of cross-linking, with favorable properties such as toughness, hardness, chemical resistance and resistance to weather and with the feasibility of being applied as the ground and finish coat on metals, wood, paper, outdoor construction or the like. Any kind of ionization radiation, particularly accelerated electron beams, ..gamma.. radiation can be used at 50/sup 0/C to -5/sup 0/C for a few seconds or minutes, permitting continuous operation. In one example, 384 parts of phthalic anhydride, 115 parts of pentaerythritol, 233 parts of trimethylol ethane, 288 parts of tung fatty acid and 49 parts of para-tertiary-butyl benzoic acid are mixed and heated with 60 parts of xylene to an acid value of 12. In addition, 271 parts of maleic anhydride and 0.6 parts of hydroquinone are admixed with the content and heated to terminate the reaction. 100 parts of a 50% stylene solution of this alkyd resin are mixed with 1 part of a 60% toluene solution of cobalt naphthenate, and then coated on a glass plate and irradiated with high energy electron beams of 300 kV with a dose of 5 Mrad for 1 sec.

An Effective Model of the Retinoic Acid Induced HL-60 Differentiation Program.

Science.gov (United States)

Tasseff, Ryan; Jensen, Holly A; Congleton, Johanna; Dai, David; Rogers, Katharine V; Sagar, Adithya; Bunaciu, Rodica P; Yen, Andrew; Varner, Jeffrey D

2017-10-30

In this study, we present an effective model All-Trans Retinoic Acid (ATRA)-induced differentiation of HL-60 cells. The model describes reinforcing feedback between an ATRA-inducible signalsome complex involving many proteins including Vav1, a guanine nucleotide exchange factor, and the activation of the mitogen activated protein kinase (MAPK) cascade. We decomposed the effective model into three modules; a signal initiation module that sensed and transformed an ATRA signal into program activation signals; a signal integration module that controlled the expression of upstream transcription factors; and a phenotype module which encoded the expression of functional differentiation markers from the ATRA-inducible transcription factors. We identified an ensemble of effective model parameters using measurements taken from ATRA-induced HL-60 cells. Using these parameters, model analysis predicted that MAPK activation was bistable as a function of ATRA exposure. Conformational experiments supported ATRA-induced bistability. Additionally, the model captured intermediate and phenotypic gene expression data. Knockout analysis suggested Gfi-1 and PPARg were critical to the ATRAinduced differentiation program. These findings, combined with other literature evidence, suggested that reinforcing feedback is central to hyperactive signaling in a diversity of cell fate programs.

The Effect of Resin-modified Glass-ionomer Cement Base and Bulk-fill Resin Composite on Cuspal Deformation.

Science.gov (United States)

Nguyen, K V; Wong, R H; Palamara, J; Burrow, M F

2016-01-01

This study investigated cuspal deformation in teeth restored with different types of adhesive materials with and without a base. Mesio-occluso-distal slot cavities of moderately large dimension were prepared on extracted maxillary premolars (n=24). Teeth were assigned to one of four groups and restored with either a sonic-activated bulk-fill resin composite (RC) (SonicFill), or a conventional nanohybrid RC (Herculite Ultra). The base materials used were a flowable nanofilled RC (Premise Flowable) and a high-viscosity resin-modified glass-ionomer cement (RMGIC) (Riva Light-Cure HV). Cuspal deflection was measured with two direct current differential transformers, each contacting a buccal and palatal cusp. Cuspal movements were recorded during and after restoration placement. Data for the buccal and palatal cusp deflections were combined to give the net cuspal deflection. Data varied widely. All teeth experienced net inward cuspal movement. No statistically significant differences in cuspal deflection were found among the four test groups. The use of a flowable RC or an RMGIC in closed-laminate restorations produced the same degree of cuspal movement as restorations filled with only a conventional nanohybrid or bulk-fill RC.

Two-photon polymerization of an epoxy-acrylate resin material system

International Nuclear Information System (INIS)

Winfield, R.J.; O'Brien, S.

2011-01-01

Improved material systems are of great interest in the development of two-photon polymerization techniques for the fabrication of three dimensional micro- and nano-structures. The properties of the photosensitive resin are important in the realisation of structures with submicron dimensions. In this study investigation of a custom organic resin, cross-linked by a two-photon induced process, using a femtosecond Ti:sapphire laser, is described. A structural, optical and mechanical analysis of the optimised material is presented. The influence of both material system and laser processing parameters on achievable micro-structure and size is presented as are representative structures. Parameters include: laser power, photo-initiator concentration and material composition.

Properties of the Carboxylate ion exchange resins

International Nuclear Information System (INIS)

Allard, Bert; Dario, Maarten; Boren, Hans; Torstenfelt, Boerje; Puigdomenech, Ignasi; Johansson, Claes

2002-09-01

Weakly acidic, carboxylic resin has been selected, together with strong base anion resins, for water purification at the Forsmark 1 and 2 reactors. For the strong (but not the weak) ion exchange resin the Nuclear Power Inspectorate has given permission to dispose the spent resins in the SFR 1 (the Final Repository for Radioactive Operational Waste). This report gives a review of the carboxylic resins and comes to the conclusion that the resins are very stable and that there should not exist any risks for increased leaching of radionuclides from SFR 1 if these resins are disposed (compared to the strong resins)

Kinetics of monomer biodegradation in soil.

Science.gov (United States)

Siotto, Michela; Sezenna, Elena; Saponaro, Sabrina; Innocenti, Francesco Degli; Tosin, Maurizio; Bonomo, Luca; Mezzanotte, Valeria

2012-01-01

In modern intensive agriculture, plastics are used in several applications (i.e. mulch films, drip irrigation tubes, string, clips, pots, etc.). Interest towards applying biodegradable plastics to replace the conventional plastics is promising. Ten monomers, which can be applied in the synthesis of potentially biodegradable polyesters, were tested according to ASTM 5988-96 (standard respirometric test to evaluate aerobic biodegradation in soil by measuring the carbon dioxide evolution): adipic acid, azelaic acid, 1,4-butanediol, 1,2-ethanediol, 1,6-hexanediol, lactic acid, glucose, sebacic acid, succinic acid and terephthalic acid. Eight replicates were carried out for each monomer for 27-45 days. The numerical code AQUASIM was applied to process the CO₂ experimental data in order to estimate values for the parameters describing the different mechanisms occurring to the monomers in soil: i) the first order solubilization kinetic constant, K(sol) (d⁻¹); ii) the first order biodegradation kinetic constant, K(b) (d⁻¹); iii) the lag time in biodegradation, t(lag) (d); and iv) the carbon fraction biodegraded but not transformed into CO₂, Y (-). The following range of values were obtained: [0.006 d⁻¹, 6.9 d⁻¹] for K(sol), [0.1 d⁻¹, 1.2 d⁻¹] for K(b), and [0.32-0.58] for Y; t(lag) was observed for azelaic acid, 1,2-ethanediol, and terephthalic acid, with estimated values between 3.0 e 4.9 d. Copyright © 2011 Elsevier Ltd. All rights reserved.

Bond strength of resin-resin interfaces contaminated with saliva and submitted to different surface treatments

Directory of Open Access Journals (Sweden)

Adilson Yoshio Furuse

2007-12-01

Full Text Available The purpose of this study was to investigate the effect of different surface treatments on shear bond strength of saliva-contaminated resin-resin interfaces. Flat resin surfaces were fabricated. In the control group, no contamination or surface treatment was performed. The resin surfaces of the experimental groups were contaminated with saliva and air-dried, and then submitted to: (G1 rinsing with water and drying; (G2 application of an adhesive system; (G3 rinsing and drying, abrasion with finishing disks, etching and application of adhesive system; (G4 rinsing and drying, etching, application of silane and adhesive system. Resin cylinders were placed over the treated surfaces. The specimens were stored in water or ethanol. Shear bond strength tests were performed and the mode of failure was evaluated. Data were submitted to two-way ANOVA and Dunnett T3 test. Contamination of resin-resin interfaces with saliva significantly reduced shear strength, especially after prolonged storage (p<0.05. Similar values to the original bond strength were obtained after abrasion and application of adhesive (G3 or etching and application of silane and adhesive (G4. If contamination occurs, a surface treatment is required to guarantee an adequate interaction between the resin increments.

Comparative study of resin sealant and resin modified glass ionomer as pit and fissure sealant

Directory of Open Access Journals (Sweden)

Shirin Malek

2017-02-01

Full Text Available The purpose of the present study was to compare the marginal integrity of resin modified glass ionomer cement with that of resin sealant, in vitro. Forty artificial pit and fissure cavities were prepared in occlusal surface of extracted premolar teeth by using ¼ round carbide bur. Cavities were condensed with artificial organic debris followed by cleaning with prophylaxis pumice brush and paste and then separated into two treatment groups. In Group A, 15 fissure cavities were sealed by resin sealant and in Group B, 15 fissure cavities were sealed by resin modified glass ionomer sealant. These specimens were subjected to thermo-cycling followed by dye penetration test. The remaining 5 cavities from each group were analyzed for debris score by the SEM. The results of the microleakage test showed that the efficacy of preventing microleakage of samples sealed by resin modified glass ionomer sealant was higher than the samples sealed by resin sealant. However, no significant differences were found. It can be concluded that use of resin modified glass ionomer sealant is a good alternative for sealing pits and fissures.

Solidification of ion exchange resins saturated with Na{sup +} ions: Comparison of matrices based on Portland and blast furnace slag cement

Energy Technology Data Exchange (ETDEWEB)

Lafond, E. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Cau dit Coumes, C., E-mail: celine.cau-dit-coumes@cea.fr [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Gauffinet, S. [Laboratoire Interdisciplinaire Carnot de Bourgogne UMR 6303 CNRS-Université de Bourgogne, Dijon, France, 9 Av Alain Savary, BP 47870, 21078 Dijon cedex (France); Chartier, D. [CEA, DEN, DTCD, SPDE, F-30207 Bagnols-sur-Cèze cedex (France); Stefan, L. [AREVA, Back End Business Group, Dismantling & Services, 1 Place Jean Millier, 92084 Paris La Défense (France); Le Bescop, P. [CEA, DEN, DPC, SECR, F-91192 Gif-sur-Yvette (France)

2017-01-15

This work is devoted to the conditioning of ion exchange resins used to decontaminate radioactive effluents. Calcium silicate cements may have a good potential to encapsulate spent resins. However, certain combinations of cement and resins produce a strong expansion of the final product, possibly leading to its full disintegration. The focus is placed on the understanding of the behaviour of cationic resins in the Na{sup +} form in Portland or blast furnace slag (CEM III/C) cement pastes. During hydration of the Portland cement paste, the pore solution exhibits a decrease in its osmotic pressure, which causes a transient expansion of small magnitude of the resins. At 20 °C, this expansion takes place just after setting in a poorly consolidated material and is sufficient to induce cracks. In the CEM III/C paste, swelling of the resins also occurs, but before the end of setting, and induces limited stress in the matrix which is still plastic. - Highlights: • Solidification of cationic resins in the Na{sup +}-form is investigated. • Portland and blast furnace slag cements are compared. • Deleterious expansion is observed with Portland cement only. • Resin swelling is due to a decrease in the osmotic pressure of the pore solution. • The consolidation rate of the matrix is a key parameter to prevent damage.

Investigation on physical behavior of styrene wood-polymer in different concentrations of monomer

Directory of Open Access Journals (Sweden)

maryam ghorbani

2016-09-01

Full Text Available This research was conducted to study the effect of different concentrations of styrene lumen monomer on the physical properties of beech wood. Physical test samples were prepared according to ASTM-D1037 standard and treated with vacuum-pressure method at five concentration levels; 0, 40, 60, 80 and 100 percent of soluble monomer. For polymerization, treated samples were heated in oven for two 24-hour period at 90 and 103ºC respectively. Monomer and polymer absorption, density variation, water absorption, swelling and anti-swelling efficiency (ASE were determined. According to the results, Monomer and polymer absorption were increment by monomer concentration increase, and they were reported 38.2% and 26% in highest level. With polymer absorption enhancement, density of wood increased from 0/63g/cm³ in control to 0/91g/cm³ in the highest monomer concentration level that reduces pores in wood-polymer structure. Absorbed polymer enhancement decreased hydrophilicity and dimensional changes of treated samples, so that water absorption and swelling volume of the samples saturated with 100% concentration of monomer were decreased 64% and 45.3% after the longest immersion time. Highest Anti-swelling efficiency of Styrene-saturated samples was determined 56.15% in the maximum concentration level of treatment.

Copolymerization of 4-Acetylphenyl Methacrylate with Ethyl Methacrylate: Synthesis, Characterization, Monomer Reactivity Ratios, and Thermal Properties

Directory of Open Access Journals (Sweden)

Gamze Barim

2014-01-01

Full Text Available Methacrylates have high glass transition temperature (Tg values and high thermal stability. A new methacrylate copolymer, poly(4-acetylphenyl methacrylate-co-ethyl methacrylate (APMA-co-EMA, was synthesized. The thermal behaviors of copolymers were investigated by differential scanning calorimetry and thermogravimetric analysis. They behaved as new single polymers with single Tg’s and the thermal stability of the copolymers increased with increasing 4-acetylphenyl methacrylate (APMA fraction, leading to the manufacture of copolymers with desired Tg values. Structure and composition of copolymers for a wide range of monomer feed ratios were determined by Fourier transform infrared (FT-IR and 1H-nuclear magnetic resonance (1H-NMR spectroscopic techniques. Copolymerization reactions were continued up to 40% conversions. The monomer reactivity ratios for copolymer system were determined by the Kelen-Tüdös (ra(APMA=0.81; rb(EMA=0.61 and extended Kelen-Tüdös (ra=0.77; rb=0.54 methods and a nonlinear least squares (ra=0.74; rb=0.49 method.

Binding interactions between suberin monomer components and pesticides

Energy Technology Data Exchange (ETDEWEB)

Olivella, M.À., E-mail: angels.olivella@udg.edu [Department of Chemical Engineering, Escola Politècnica Superior, Universitat de Girona, Maria Aurèlia Capmany, 61, 17071 Girona (Spain); Bazzicalupi, C.; Bianchi, A. [Department of Chemistry “Ugo Schiff”, University of Florence, Via della Lastruccia, 3, 50019 Sesto Fiorentino (Italy); Río, J.C. del [Instituto de Recursos Naturales y Agrobiología de Sevilla, Consejo Superior de Investigaciones Científicas, P.O. Box 1052, 41080 Seville (Spain); Fiol, N.; Villaescusa, I. [Department of Chemical Engineering, Escola Politècnica Superior, Universitat de Girona, Maria Aurèlia Capmany, 61, 17071 Girona (Spain)

2015-09-15

Understanding the role of biomacromolecules and their interactions with pollutants is a key for elucidating the sorption mechanisms and making an accurate assessment of the environmental fate of pollutants. The knowledge of the sorption properties of the different constituents of these biomacromolecules may furnish a significant contribution to this purpose. Suberin is a very abundant biopolymer in higher plants. In this study, suberin monomers isolated from cork were analyzed by thermally-assisted methylation with tetramethylammonium hydroxide (TMAH) in a pyrolysis unit coupled to gas chromatography–mass spectrometry (GC/MS). The isolated monomer mixture was used to study the sorption of three pesticides (isoproturon, methomyl and oxamyl). The modes of pesticide–sorbent interactions were analyzed by means of two modeling calculations, the first one representing only the mixture of suberin monomers used in the sorption study, and the second one including glycerol to the mixture of suberin monomers, as a building block of the suberin molecule. The results indicated that the highest sorption capacity exhibited by the sorbent was for isoproturon (33%) being methomyl and oxamyl sorbed by the main suberin components to a lesser extent (3% and < 1%, respectively). In addition to van der Waals interactions with the apolar region of sorbent and isoproturon, modeling calculations evidenced the formation of a hydrogen bond between the isoproturon NH group and a carboxylic oxygen atom of a suberin monomer. In the case of methomyl and oxamyl only weak van der Waals interactions stabilize the pesticide–sorbent adducts. The presence of glycerol in the model provoked significant changes in the interactions with isoproturon and methomyl. - Highlights: • Suberin has low affinity to retain pesticides of aliphatic character. • Suberin has a moderate affinity to adsorb isoproturon. • Modeling calculations show that apolar portion of suberin interacts with isoproturon. �

Binding interactions between suberin monomer components and pesticides

International Nuclear Information System (INIS)

Olivella, M.À.; Bazzicalupi, C.; Bianchi, A.; Río, J.C. del; Fiol, N.; Villaescusa, I.

2015-01-01

Understanding the role of biomacromolecules and their interactions with pollutants is a key for elucidating the sorption mechanisms and making an accurate assessment of the environmental fate of pollutants. The knowledge of the sorption properties of the different constituents of these biomacromolecules may furnish a significant contribution to this purpose. Suberin is a very abundant biopolymer in higher plants. In this study, suberin monomers isolated from cork were analyzed by thermally-assisted methylation with tetramethylammonium hydroxide (TMAH) in a pyrolysis unit coupled to gas chromatography–mass spectrometry (GC/MS). The isolated monomer mixture was used to study the sorption of three pesticides (isoproturon, methomyl and oxamyl). The modes of pesticide–sorbent interactions were analyzed by means of two modeling calculations, the first one representing only the mixture of suberin monomers used in the sorption study, and the second one including glycerol to the mixture of suberin monomers, as a building block of the suberin molecule. The results indicated that the highest sorption capacity exhibited by the sorbent was for isoproturon (33%) being methomyl and oxamyl sorbed by the main suberin components to a lesser extent (3% and < 1%, respectively). In addition to van der Waals interactions with the apolar region of sorbent and isoproturon, modeling calculations evidenced the formation of a hydrogen bond between the isoproturon NH group and a carboxylic oxygen atom of a suberin monomer. In the case of methomyl and oxamyl only weak van der Waals interactions stabilize the pesticide–sorbent adducts. The presence of glycerol in the model provoked significant changes in the interactions with isoproturon and methomyl. - Highlights: • Suberin has low affinity to retain pesticides of aliphatic character. • Suberin has a moderate affinity to adsorb isoproturon. • Modeling calculations show that apolar portion of suberin interacts with isoproturon. �

Pseudomonas syringae evades host Immunity by degrading flagellin monomers with alkaline protease AprA

OpenAIRE

Pel, M.J.C.; Van Dijken, A.J.H.; Bardoel, B.W.; Seidl, M.F; Van der Ent, S.; Van Strijp, J.A.G.

2014-01-01

Bacterial flagellin molecules are strong inducers of innate immune responses in both mammals and plants. The opportunistic pathogen Pseudomonas aeruginosa secretes an alkaline protease called AprA that degrades flagellin monomers. Here, we show that AprA is widespread among a wide variety of bacterial species. In addition, we investigated the role of AprA in virulence of the bacterial plant athogen P. syringae pv. tomato DC3000. The AprA-deficient DC3000 ΔaprA knockout mutant was significantl...

Latexin is involved in bone morphogenetic protein-2-induced chondrocyte differentiation

International Nuclear Information System (INIS)

Kadouchi, Ichiro; Sakamoto, Kei; Tangjiao, Liu; Murakami, Takashi; Kobayashi, Eiji; Hoshino, Yuichi; Yamaguchi, Akira

2009-01-01

Latexin is the only known carboxypeptidase A inhibitor in mammals. We previously demonstrated that BMP-2 significantly induced latexin expression in Runx2-deficient mesenchymal cells (RD-C6 cells), during chondrocyte and osteoblast differentiation. In this study, we investigated latexin expression in the skeleton and its role in chondrocyte differentiation. Immunohistochemical studies revealed that proliferating and prehypertrophic chondrocytes expressed latexin during skeletogenesis and bone fracture repair. In the early phase of bone fracture, latexin mRNA expression was dramatically upregulated. BMP-2 upregulated the expression of the mRNAs of latexin, Col2a1, and the gene encoding aggrecan (Agc1) in a micromass culture of C3H10T1/2 cells. Overexpression of latexin additively stimulated the BMP-2-induced expression of the mRNAs of Col2a, Agc1, and Col10a1. BMP-2 treatment upregulated Sox9 expression, and Sox9 stimulated the promoter activity of latexin. These results indicate that latexin is involved in BMP-2-induced chondrocyte differentiation and plays an important role in skeletogenesis and skeletal regeneration.

Nicotinamide induces differentiation of embryonic stem cells into insulin-secreting cells

International Nuclear Information System (INIS)

Vaca, Pilar; Berna, Genoveva; Araujo, Raquel; Carneiro, Everardo M.; Bedoya, Francisco J.; Soria, Bernat; Martin, Franz

2008-01-01

The poly(ADP-ribose) polymerase (PARP) inhibitor, nicotinamide, induces differentiation and maturation of fetal pancreatic cells. In addition, we have previously reported evidence that nicotinamide increases the insulin content of cells differentiated from embryonic stem (ES) cells, but the possibility of nicotinamide acting as a differentiating agent on its own has never been completely explored. Islet cell differentiation was studied by: (i) X-gal staining after neomycin selection; (ii) BrdU studies; (iii) single and double immunohistochemistry for insulin, C-peptide and Glut-2; (iv) insulin and C-peptide content and secretion assays; and (v) transplantation of differentiated cells, under the kidney capsule, into streptozotocin (STZ)-diabetic mice. Here we show that undifferentiated mouse ES cells treated with nicotinamide: (i) showed an 80% decrease in cell proliferation; (ii) co-expressed insulin, C-peptide and Glut-2; (iii) had values of insulin and C-peptide corresponding to 10% of normal mouse islets; (iv) released insulin and C-peptide in response to stimulatory glucose concentrations; and (v) after transplantation into diabetic mice, normalized blood glucose levels over 7 weeks. Our data indicate that nicotinamide decreases ES cell proliferation and induces differentiation into insulin-secreting cells. Both aspects are very important when thinking about cell therapy for the treatment of diabetes based on ES cells

Method of solidifying radioactive ion exchange resin

International Nuclear Information System (INIS)

Minami, Yuji; Tomita, Toshihide

1989-01-01

Spent anion exchange resin formed in nuclear power plants, etc. generally catch only a portion of anions in view of the ion exchange resins capacity and most of the anions are sent while possessing activities to radioactive waste processing systems. Then, the anion exchange resins increase the specific gravity by the capture of the anions. Accordingly, anions are caused to be captured on the anion exchange resin wastes such that the specific gravity of the anion exchange resin wastes is greater than that of the thermosetting resins to be mixed. This enables satisfactory mixing with the thermosetting resins and, in addition, enables to form integral solidification products in which anion exchange resins and cation exchange resins are not locallized separately and which are homogenous and free from cracks. (T.M.)

Improvement of antithrombogenicity of a fluoro polymer by radiation-induced grafting of hydrophilic monomer

International Nuclear Information System (INIS)

Otsuhata, Kazushige; Razzak, M.T.; Tabata, Yoneho; Ohashi, Fumito; Takeuchi, Atsushi.

1985-01-01

Fluoro polymers have been used as biomaterials in medical field since they have good compatibility with both tissue and blood, and their biomaterial application are of variety. Blood compatibility of fluoro polymers, however, are not always enough for every applications. Especially, there is a large difficulty in the application for artificial vessel with small radius below than 4 mm. In the present study, grafting of a hydrophilic monomer onto a fluoro polymer has been carried out to improve blood compatibility of the fluoro polymer. The technique of grafting employed here was simultaneous irradiation method of gamma rays from a 60 Co source. The fluoro polymer and the hydrophilic monomer used in the experiment were alternative copolymer of ethylene and tetrafluoethylene(AFLON) and N,N-dimethylacry lamide(DMAA), respectively. After grafting, it was found by in vitro tests that antithrombogenicity of AFLON was improved by grafting of DMAA. It was, however, also found that degree of the improvement is affected by grafting conditions. When ethyl acetate was used as a solvent for the graft copolymerization, the improvement was affected by dose rate. Blood compatibility of DMAA-g-AFLON obtained at a higher dose rate of 1 x 10 5 rad/h was not improved, while it was improved in the sample of DMAA-g-AFLON obtained at a lower dose rate of 1 x 10 4 rad/h. On the other hand, when acetone was used as a solvent for the grafting, the degree of grafting gave a significant effect on the improvement. Blood compatibility of all samples with grafting percent more than 20 % was improved by grafting of DMAA. (author)

Physicochemical and bioactive properties of innovative resin-based materials containing functional halloysite-nanotubes fillers.

Science.gov (United States)

Degrazia, Felipe Weidenbach; Leitune, Vicente Castelo Branco; Takimi, Antonio Shigueaki; Collares, Fabrício Mezzomo; Sauro, Salvatore

2016-09-01

This study aimed to assess the degree of conversion, microhardness, solvent degradation, contact angle, surface free energy and bioactivity (e.g., mineral precipitation) of experimental resin-based materials containing, pure or triclosan-encapsulated, aluminosilicate-(halloysite) nanotubes. An experimental resin blend was prepared using bis-GMA/TEGDMA, 75/25wt% (control). Halloysite nanotubes (HNT) doped with or without triclosan (TCN) were first analyzed using transmission electron microscopy (TEM). HNT or HNT/TCN fillers were incorporated into the resin blend at different concentrations (5, 10, and 20wt%). Seven experimental resins were created and the degree of conversion, microhardness, solvent degradation and contact angle were assessed. Bioactive mineral precipitation induced by the experimental resins was evaluated through Raman spectroscopy and SEM-EDX. TEM showed a clear presence of TCN particles inside the tubular lumen and along the outer surfaces of the halloysite nanotubes. The degree of conversion, surface free energy, microhardness, and mineral deposition of polymers increased with higher amount of HNTs. Conversely, the higher the amount (20wt%) of TCN-loaded HNTs the lower the microhardness of the experimental resins. The incorporation of pure or TCN-loaded aluminosilicate-(halloysite) nanotubes into resin-based materials increase the bioactivity of such experimental restorative materials and promotes mineral deposition. Therefore, innovative resin-based materials containing functional halloysite-nanotube fillers may represent a valuable alternative for therapeutic minimally invasive treatments. Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Action of ionizing radiation on epoxy resins

Energy Technology Data Exchange (ETDEWEB)

Van de Voorde, M. E.

1970-12-01

The resistance of classical and experimental epoxy resins to irradiation was studied. The resistance to irradiation of epoxy resins of diverse compositions as well as the development of resins having a radioresistance that approaches that of certain ceramics are discussed. Sources of irradiation and the techniques of dosimetry used are described. The structures of certain epoxy resins and of hardeners are given. The preparation of these resins and their physical properties is described. The effects of radiation on epoxy resins, as well as conditions of irradiation, and suggested mechanisms for degradation of the irradiated resins are discussed. The relationship between chemical structure of the resins and their physical properties is evaluated. (115 references) (JCB)

Identification of salt-stress induced differentially expressed genes in ...

African Journals Online (AJOL)

Identification of salt-stress induced differentially expressed genes in barley leaves using the annealingcontrol- primer-based GeneFishing technique. S Lee, K Lee, K Kim, GJ Choi, SH Yoon, HC Ji, S Seo, YC Lim, N Ahsan ...

Antibacterial and remineralizing orthodontic adhesive containing quaternary ammonium resin monomer and amorphous calcium phosphate nanoparticles.

Science.gov (United States)

Liu, Yan; Zhang, Ling; Niu, Li-Na; Yu, Tao; Xu, Hockin H K; Weir, Michael D; Oates, Thomas W; Tay, Franklin R; Chen, Ji-Hua

2018-05-01

To evaluate the bonding performance, antibacterial activity, and remineralization effect on enamel of the orthodontic adhesive containing MAE-DB and NACP. Eighty non-carious human premolars were divided into 3 groups: Transbond XT (TB), PEHB + 5% MAE-DB (PD), and PEHB + 40% NACP + 5% MAE-DB (PND). Premolars were bonded with orthodontic brackets, the first subgroup (n = 10) and the second subgroup (n = 10) were subjected to shear bond strength testing after immersed in water for 1 day and in demineralization solution for 28 days respectively and then tested surface roughness, while the third subgroup (n = 6) was used for microhardness evaluation after aged in demineralization solution for 28 days. For each adhesive, fifty disk samples were prepared for antibacterial study. Specimens measuring 12 mm × 2 mm × 2 mm were fabricated for ion release test. Bond strengths were in the order TB = PND > PND = PD for "1-day in water", and in the order TB = PND > PD for "28-days in pH 4 solution". No significant difference in the ARI scores for the three adhesive. Numerous bacteria adhered to TB surface, while PD and PND had minimal bacterial growth and activity. PND showed high levels of Ca and P ions release and enamel hardness. The surface roughness of enamel in PND was much lower than TB and PD and showed no significant difference with the sound, control enamel. PND adhesive with 5% MAE-DB and 40% NACP exhibits antibacterial and remineralizing capabilities, and did not adversely affect bond strength compared to commercial adhesive. Novel adhesive containing quaternary ammonium monomer and nano-amorphous calcium phosphate represents a promising candidate in combating enamel white spot lesions and even dental caries. Copyright © 2018 Elsevier Ltd. All rights reserved.

Distinct cellular responses differentiating alcohol- and hepatitis C virus-induced liver cirrhosis

Directory of Open Access Journals (Sweden)

Boix Loreto

2006-11-01

Full Text Available Abstract Background Little is known at the molecular level concerning the differences and/or similarities between alcohol and hepatitis C virus induced liver disease. Global transcriptional profiling using oligonucleotide microarrays was therefore performed on liver biopsies from patients with cirrhosis caused by either chronic alcohol consumption or chronic hepatitis C virus (HCV. Results Global gene expression patterns varied significantly depending upon etiology of liver disease, with a greater number of differentially regulated genes seen in HCV-infected patients. Many of the gene expression changes specifically observed in HCV-infected cirrhotic livers were expectedly associated with activation of the innate antiviral immune response. We also compared severity (CTP class of cirrhosis for each etiology and identified gene expression patterns that differentiated ethanol-induced cirrhosis by class. CTP class A ethanol-cirrhotic livers showed unique expression patterns for genes implicated in the inflammatory response, including those related to macrophage activation and migration, as well as lipid metabolism and oxidative stress genes. Conclusion Stages of liver cirrhosis could be differentiated based on gene expression patterns in ethanol-induced, but not HCV-induced, disease. In addition to genes specifically regulating the innate antiviral immune response, mechanisms responsible for differentiating chronic liver damage due to HCV or ethanol may be closely related to regulation of lipid metabolism and to effects of macrophage activation on deposition of extracellular matrix components.

Radiation induced change in the affinity of a plastic resin to chlorine contained in artificial tap water

International Nuclear Information System (INIS)

Fujiyoshi, Ryoko; Sawamura, Sadashi; Katayama, Meiseki

1985-01-01

γ-Radiation curing of a polyacetal resin was attempted in order to eliminate the unsuitable property for the joints of tap water pipes. In the case of non-irradiated resin, almost all available chlorine (AC) contained in usual tap water disappeared. γ-Irradiation of the resin showed an indirect effect on eliminating such a property; that is, a decrease in the amount of AC from artificial tap water (test solution) showed a decrease to JIS (Japan Industrial Standards) level of requirement at certain absorption doses. However, it was also found that the decrease in the amount of AC from the test solution increased with time after γ-irradiation. (author)

Epoxidation of linseed oil-Alkyd resins

International Nuclear Information System (INIS)

Motawie, A.M.; Ismail, E.A.; Mazroua, A.M.; Abd EI Aziem, M.S.; Ramadan, A.M.

2004-01-01

Three types of different linseed oil-alkyd resin ( Alk (I), Alk (II), and Alk (III) ) were prepared with the calculated amounts of mono glycerides and adipic acid (1:1, 1:2, and 2:1 Eq.Wt) respectively via monoglyceride method. The obtained alkyd resins were epoxidized via reaction with the calculated quantities of peracetic acid, which was prepared by the reaction of acetic anhydride with H 2 O 2 . Epoxidation occurred with the ratio (1: 1, 1 :3, and 1:6 Eq. Wt) of alkyd to peracetic acid. The effect of reaction time on the epoxy group content was measured during the epoxidation process. The prepared alkyd resins were analyzed by IR and H 1 NMR. The metal coated film properties of epoxidized alkyd resins were compared with those of unmodified alkyd resins. It was observed that the coating films of epoxidized alkyd resins have better in drying properties, hardness, adhesion, impact and flexibility than those of un epoxidized alkyd resins. The flammability properties of the paper coated films for the prepared brominated epoxidized alkyd resins were found to be fire retardant

ERα inhibited myocardin-induced differentiation in uterine fibroids

Energy Technology Data Exchange (ETDEWEB)

Liao, Xing-Hua, E-mail: xinghualiao@hotmail.com [Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan, 430065 (China); Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education and Tianjin, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457 (China); Li, Jun-Yan [Henan Vocational College of Applied Technology, Zhengzhou 450042 (China); Dong, Xiu-Mei [Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan, 430065 (China); Yuncheng County People' s Hospital, Shandong 274700 (China); Wang, Xiuhong [Xianning Central Hospital, Department of Obstetrics and Gynecology, Xianning, Hubei 437100 (China); Xiang, Yuan; Li, Hui; Yu, Cheng-Xi; Li, Jia-Peng; Yuan, Bai-Yin [Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan, 430065 (China); Zhou, Jun, E-mail: zhoujun@wust.edu.cn [Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan, 430065 (China); School of Medicine, Wuhan University of Science and Technology, Wuhan 430065 (China); Zhang, Tong-Cun, E-mail: zhangtongcun@wust.edu.cn [Institute of Biology and Medicine, Wuhan University of Science and Technology, Wuhan, 430065 (China); Key Laboratory of Industrial Fermentation Microbiology, Ministry of Education and Tianjin, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300457 (China)

2017-01-01

Uterine fibroids, also known as uterine leiomyomas, are a benign tumor of the human uterus and the commonest estrogen-dependent benign tumor found in women. Myocardin is an important transcriptional regulator in smooth and cardiac muscle development. The role of myocardin and its relationship with ERα in uterine fibroids have barely been addressed. We noticed that the expression of myocardin was markedly reduced in human uterine fibroid tissue compared with corresponding normal or adjacent myometrium tissue. Here we reported that myocardin induced the transcription and expression of differentiation markers SM22α and alpha smooth muscle actin (α-SMA) in rat primary uterine smooth muscle cells (USMCs) and this effect was inhibited by ERα. Notably, we showed that, ERα induced expression of proliferation markers PCNA and ki-67 in rat primary USMCs. We also found ERα interacted with myocardin and formed complex to bind to CArG box and inhibit the SM22α promoter activity. Furthermore, ERα inhibited the transcription and expression of myocardin, and reduced the levels of transcription and expression of downstream target SM22α, a SMC differentiation marker. Our data thus provided important and novel insights into how ERα and myocardin interact to control the cell differentiation and proliferation of USMCs. Thus, it may provide potential therapeutic target for uterine fibroids.

Self-assembly of actin monomers into long filaments: Brownian Dynamics simulations

DEFF Research Database (Denmark)

Shillcock, Julian C.

2009-01-01

Brownian dynamics simulations are used to study the dynamical process of self-assembly of actin monomers into long filaments containing up to 1000 actin protomers. In order to overcome the large separation of time scales between the diffusive motion of the freemonomers and the relatively slow....../detachment events. When a single filament is allowed to grow in a bath of constant concentration of free ADP-actin monomers, its growth rate increases linearly with the free monomer concentration in quantitative agreement with in vitro experiments. Theresults also show that the waiting time is governed by...

Oxygen index tests of thermosetting resins

Science.gov (United States)

Gilwee, W. J., Jr.; Parker, J. A.; Kourtides, D. A.

1980-01-01

The flammability characteristics of nine thermosetting resins under evaluation for use in aircraft interiors are described. These resins were evaluated using the Oxygen Index (ASTM 2863) testing procedure. The test specimens consisted of both neat resin and glass reinforced resin. When testing glass-reinforced samples it was observed that Oxygen Index values varied inversely with resin content. Oxygen values were also obtained on specimens exposed to temperatures up to 300 C. All specimens experienced a decline in Oxygen Index when tested at an elevated temperature.

Study on the pyrolysis of phenol-formaldehyde (PF) resin and modified PF resin

Energy Technology Data Exchange (ETDEWEB)

Wang, Jigang, E-mail: wangjigang@seu.edu.cn [Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); Jiang, Haiyun [Jiangsu Key Laboratory of Advanced Metallic Materials, School of Materials Science and Engineering, Southeast University, Nanjing 211189 (China); School of Materials Science and Engineering, Southeast University, Nanjing Institute of Technology, Nanjing 210013 (China); Jiang, Nan [Institute of Theoretical and Computational Chemistry, Nanjing University, Nanjing 210093 (China)

2009-12-10

The pyrolysis of pure phenol-formaldehyde (PF) resin and boron carbide (B{sub 4}C) modified PF resin was investigated by using thermogravimetry (TG) and pyrolysis gas-chromatography-mass-spectrometry (PY-GC/MS). Scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) spectroscopy were also employed to investigate the micro-structural evolution. It was shown from the TG analysis that the char residues of pure PF resin were 62.9 and 60.5% after being pyrolyzed at 700 and 1000 {sup o}C, respectively. The degradation and failure of the resin matrix were mainly resulted from the release of volatiles. The phenol and its methyl derivates took a large proportion in the amount of volatiles. In comparison with the pure PF resin, the char residues of B{sub 4}C modified PF resin were obviously higher, with the values of 71.9 and 68.4% at 700 and 1000 {sup o}C, respectively. Due to the oxidation-reduction reactions between B{sub 4}C additive and oxygen-containing volatiles including CO and H{sub 2}O, partial carbon and oxygen elements in the volatiles remained in the resin matrix in the forms of amorphous carbon and B{sub 2}O{sub 3}, respectively. The results of SEM and FT-IR characterization demonstrated the occurrence of the modification, and the amorphous carbon existed in the form of reticular substance. In addition, the amount of the released phenol and its methyl derivates was also decreased drastically due to the formation of borate.

1-Butanol absorption in poly(styrene-divinylbenzene) ion exchange resins for catalysis.

Science.gov (United States)

Pérez-Maciá, M A; Curcó, D; Bringué, R; Iborra, M; Rodríguez-Ropero, F; van der Vegt, N F A; Aleman, Carlos

2015-12-21

The swelling behaviour of poly(styrene-co-divinylbenzene), P(S-DVB), ion exchange resins in 1-butanol (BuOH) has been studied by means of atomistic classical molecular dynamics simulations (MD). The topological characteristics reported for the resin in the dry state, which exhibited complex internal loops (macropores), were considered for the starting models used to examine the swelling induced by BuOH contents ranging from 10% to 50% w/w. Experimental measurements using a laser diffraction particle size analyzer indicate that swelling causes a volume variation with respect to the dry resin of 21%. According to MD simulations, such a volume increment corresponds to a BuOH absorption of 31-32% w/w, which is in excellent agreement with the indirect experimental estimation (i.e. 31% w/w). Simulations reveal that, independently of the content of BuOH, the density of the swelled resin is higher than that of the dry resin, evidencing that the alcohol provokes important structural changes in the polymeric matrix. Thus, BuOH molecules cause a collapse of the resin macropores when the content of alcohol is ≤20% w/w. In contrast, when the concentration of BuOH is close to the experimental value (∼30% w/w), P(S-DVB) chains remain separated by pores faciliting the access of the reactants to the reaction centers. On the other hand, evaluation of both bonding and non-bonding interactions indicates that the mixing energy is the most important contribution to the absorption of BuOH into the P(S-DVB) resin. Overall, the results displayed in this work represent a starting point for the theoretical study of the catalytic conversion of BuOH into di-n-butyl ether in P(S-DVB) ion exchange resins using sophisticated electronic methods.

Controlled grafting of vinylic monomers on polyolefins: a robust mathematical modeling approach.

Science.gov (United States)

Saeb, Mohammad Reza; Rezaee, Babak; Shadman, Alireza; Formela, Krzysztof; Ahmadi, Zahed; Hemmati, Farkhondeh; Kermaniyan, Tayebeh Sadat; Mohammadi, Yousef

2017-01-01

Experimental and mathematical modeling analyses were used for controlling melt free-radical grafting of vinylic monomers on polyolefins and, thereby, reducing the disturbance of undesired cross-linking of polyolefins. Response surface, desirability function, and artificial intelligence methodologies were blended to modeling/optimization of grafting reaction in terms of vinylic monomer content, peroxide initiator concentration, and melt-processing time. An in-house code was developed based on artificial neural network that learns and mimics processing torque and grafting of glycidyl methacrylate (GMA) typical vinylic monomer on high-density polyethylene (HDPE). Application of response surface and desirability function enabled concurrent optimization of processing torque and GMA grafting on HDPE, through which we quantified for the first time competition between parallel reactions taking place during melt processing: (i) desirable grafting of GMA on HDPE; (ii) undesirable cross-linking of HDPE. The proposed robust mathematical modeling approach can precisely learn the behavior of grafting reaction of vinylic monomers on polyolefins and be placed into practice in finding exact operating condition needed for efficient grafting of reactive monomers on polyolefins.

BMP9-Induced Osteogenetic Differentiation and Bone Formation of Muscle-Derived Stem Cells

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Li Xiang

2012-01-01

Full Text Available Efficient osteogenetic differentiation and bone formation from muscle-derived stem cells (MDSCs should have potential clinical applications in treating nonunion fracture healing or bone defects. Here, we investigate osteogenetic differentiation ability of MDSCs induced by bone morphogenetic protein 9 (BMP9 in vitro and bone formation ability in rabbit radius defects repairing model. Rabbit's MDSCs were extracted by type I collagenase and trypsin methods, and BMP9 was introduced into MDSCs by infection with recombinant adenovirus. Effects of BMP9-induced osteogenetic differentiation of MDSCs were identified with alkaline phosphatase (ALP activity and expression of later marker. In stem-cell implantation assay, MDSCs have also shown valuable potential bone formation ability induced by BMP9 in rabbit radius defects repairing test. Taken together, our findings suggest that MDSCs are potentiated osteogenetic stem cells which can be induced by BMP9 to treat large segmental bone defects, nonunion fracture, and/or osteoporotic fracture.

Sphingosine 1-phosphate receptor activation enhances BMP-2-induced osteoblast differentiation

Energy Technology Data Exchange (ETDEWEB)

Sato, Chieri [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan); Iwasaki, Tsuyoshi, E-mail: tsuyo-i@huhs.ac.jp [Division of Pharmacotherapy, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, 1-3-6 Minatojima, Chuo-ku, Kobe 650-8530 (Japan); Kitano, Sachie; Tsunemi, Sachi; Sano, Hajime [Division of Rheumatology, Department of Internal Medicine, Hyogo College of Medicine, 1-1 Mukogawa-cho, Nishinomiya, Hyogo 663-8501 (Japan)

2012-06-22

Highlights: Black-Right-Pointing-Pointer We investigated the role of S1P signaling for osteoblast differentiation. Black-Right-Pointing-Pointer Both S1P and FTY enhanced BMP-2-stimulated osteoblast differentiation by C2C12 cells. Black-Right-Pointing-Pointer S1P signaling enhanced BMP-2-stimulated Smad and ERK phosphorylation by C2C12 cells. Black-Right-Pointing-Pointer MEK/ERK signaling is a pathway underlying S1P signaling for osteoblast differentiation. -- Abstract: We previously demonstrated that sphingosine 1-phosphate (S1P) receptor-mediated signaling induced proliferation and prostaglandin productions by synovial cells from rheumatoid arthritis (RA) patients. In the present study we investigated the role of S1P receptor-mediated signaling for osteoblast differentiation. We investigated osteoblast differentiation using C2C12 myoblasts, a cell line derived from murine satellite cells. Osteoblast differentiation was induced by the treatment of bone morphogenic protein (BMP)-2 in the presence or absence of either S1P or FTY720 (FTY), a high-affinity agonist of S1P receptors. Osteoblast differentiation was determined by osteoblast-specific transcription factor, Runx2 mRNA expression, alkaline phosphatase (ALP) activity and osteocalcin production by the cells. Smad1/5/8 and extracellular signal-regulated kinase (ERK) 1/2 phosphorylation was examined by Western blotting. Osteocalcin production by C2C12 cells were determined by ELISA. Runx2 expression and ALP activity by BMP-2-stimulated C2C12 cells were enhanced by addition of either S1P or FTY. Both S1P and FTY enhanced BMP-2-induced ERK1/2 and Smad1/5/8 phosphorylation. The effect of FTY was stronger than that of S1P. S1P receptor-mediated signaling on osteoblast differentiation was inhibited by addition of mitogen-activated protein kinase/ERK kinase (MEK) 1/2 inhibitor, indicating that the S1P receptor-mediated MEK1/2-ERK1/2 signaling pathway enhanced BMP-2-Smad signaling. These results indicate that S1P

Random small interfering RNA library screen identifies siRNAs that induce human erythroleukemia cell differentiation.

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Fan, Cuiqing; Xiong, Yuan; Zhu, Ning; Lu, Yabin; Zhang, Jiewen; Wang, Song; Liang, Zicai; Shen, Yan; Chen, Meihong

2011-03-01

Cancers are characterized by poor differentiation. Differentiation therapy is a strategy to alleviate malignant phenotypes by inducing cancer cell differentiation. Here we carried out a combinatorial high-throughput screen with a random siRNA library on human erythroleukemia K-562 cell differentiation. Two siRNAs screened from the library were validated to be able to induce erythroid differentiation to varying degrees, determined by CD235 and globin up-regulation, GATA-2 down-regulation, and cell growth inhibition. The screen we performed here is the first trial of screening cancer differentiation-inducing agents from a random siRNA library, demonstrating that a random siRNA library can be considered as a new resource in efforts to seek new therapeutic agents for cancers. As a random siRNA library has a broad coverage for the entire genome, including known/unknown genes and protein coding/non-coding sequences, screening using a random siRNA library can be expected to greatly augment the repertoire of therapeutic siRNAs for cancers.

Photokopolimerisasi monomer akrilat degan kulit kras sapi

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Dwi Wahini Nurhajati

1997-06-01

Full Text Available The research on photocopolymerization of acrylate monomer with cow crust hide had object to observe the resulted copolymer onto cow crust hide. Crust hides, saturated with aqueous emulsions containing 25 wt % of n-butyl acrylate (n-BA or tripropylene glycol diacrylate (TPGDA were irradiated by cobalt – 60 gamma rays with doses ranges from 5 to 25 kGy. The irradiated hides were washed with water, dried in air and extracted in soxhlet apparatus for 48 hours to remove homopolymer. The highest yield of photocopolymerization of n – butyl acrylate monomer with crust hides was found 17,7878% at dose 25 kGy, and for photocopolymerization of tripropylene glycol diacrylate with crust hides was found 39,4245% at dose 20 kGy.

Radical copolymerization in homogenous medium and emulsion system monomers acrylonitrile/styrene

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Boussehel H.

2013-09-01

Full Text Available This study examines the radical copolymerization in homogeneous and emulsion of the monomer system acrylonitrile/styrene. These copolymers are of great interest to the plastics industry, because they combine the good mechanical properties and implementation provided by the styrene units in the very high solvent resistance and extreme gas impermeability provided by the acrylonitrile units. The properties of a copolymer are directly related to its composition and distribution of monomer units in its macromolecular chains. Based on the reports of the couple reactivity's of monomers (AN/S found in the literature, the objective of the work is to provide theoretical simulation (by analytical and numerical integration of the equation of copolymerization: The kinetics of the reaction copolymerization of AN/S in a homogeneous medium and emulsion (drift composition, azeotropic and the microstructure (distribution of monomer sequences and the glass transition property of the macromolecular chains instant formed throughout the copolymerization reaction.

Input to Resin Column Structural Analysis if Autocatalytic Resin Reaction Occurs in HB-Line Phase II

Energy Technology Data Exchange (ETDEWEB)

Hallman, D.F.

2001-07-10

Solutions of plutonium in nitric acid are purified and concentrated using anion resin prior to precipitation. There have been instances of resin column explosions caused by autocatalytic reactions of anion resins in nitric acid within the DOE complex

Thermal, chemical and pH induced unfolding of turmeric root lectin: modes of denaturation.

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Himadri Biswas

Full Text Available Curcuma longa rhizome lectin, of non-seed origin having antifungal, antibacterial and α-glucosidase inhibitory activities, forms a homodimer with high thermal stability as well as acid tolerance. Size exclusion chromatography and dynamic light scattering show it to be a dimer at pH 7, but it converts to a monomer near pH 2. Circular dichroism spectra and fluorescence emission maxima are virtually indistinguishable from pH 7 to 2, indicating secondary and tertiary structures remain the same in dimer and monomer within experimental error. The tryptophan environment as probed by acrylamide quenching data yielded very similar data at pH 2 and pH 7, implying very similar folding for monomer and dimer. Differential scanning calorimetry shows a transition at 350.3 K for dimer and at 327.0 K for monomer. Thermal unfolding and chemical unfolding induced by guanidinium chloride for dimer are both reversible and can be described by two-state models. The temperatures and the denaturant concentrations at which one-half of the protein molecules are unfolded, are protein concentration-dependent for dimer but protein concentration-independent for monomer. The free energy of unfolding at 298 K was found to be 5.23 Kcal mol-1 and 14.90 Kcal mol-1 for the monomer and dimer respectively. The value of change in excess heat capacity upon protein denaturation (ΔCp is 3.42 Kcal mol-1 K-1 for dimer. The small ΔCp for unfolding of CLA reflects a buried hydrophobic core in the folded dimeric protein. These unfolding experiments, temperature dependent circular dichroism and dynamic light scattering for the dimer at pH 7 indicate its higher stability than for the monomer at pH 2. This difference in stability of dimeric and monomeric forms highlights the contribution of inter-subunit interactions in the former.

Thermosetting behavior of pitch-resin from heavy residue

Energy Technology Data Exchange (ETDEWEB)

Qingfang, Z.; Yansheng, G.; Baohua, H.; Yuzhen, Z. [China Univ. of Petroleum, Dongying, Shandong (China). State Key LAboratory of Heavy Oil Processing, Heavy Oil Research Inst.

2006-07-01

Thermosetting resins are widely employed as a basic matrix for c/c composites in carbon materials production. A new type of synthesized thermosetting resin is called pitch resin. Pitch resin is a cheaper resin and possesses a potential opportunity for future use. However, the thermosetting behavior of pitch resin is not very clear. The hardening process and conditions for thermosetting are very important for future use of pitch resin. B-stage pitch resin is a soluble and meltable inter-media condensed polymer, which is not fully reacted and is of a low molecular weight. The insoluble and unmelted pitch resin can only be obtained from synthesized B-stage resin after a hardening stage. This paper presented an experiment that synthesized B-stage pitch resin with a link agent (PXG) under catalyst action from fluid catalytic cracking (FCC) of the slurry's aromatic enriched component (FCCDF). The paper discussed the experiment, including the synthesis of pitch resin and thermosetting of pitch resin. Two kinds of thermosetting procedures were used in the study called one-step thermosetting and two-step thermosetting. It was concluded that the B-stage pitch resin could be hardened after a thermosetting procedure by heat treatment. The thermosetting pitch resin from 2-step thermosetting possesses was found to have better thermal resistant properties than that of the 1-step thermosetting pitch resin. 13 refs., 2 tabs., 6 figs.

On-line measurement of residual monomer during polymerisation of acrylamide using ultrasonics

International Nuclear Information System (INIS)

Ponraju, D.; Sebastian, Letha; Viswanathan, S.; Natarajan, A.; Palanichamy, P.; Jayakumar, T.; Baldev Raj

1996-01-01

An ultrasonic technique for the estimation of residual acrylamide monomer during the polymerization of aqueous acrylamide solution has been investigated. Polyacrylamide gel medium serves as a sensitive medium for detection and dosimetry of fast and thermal neutrons. This technique is based on the fact that the velocity of ultrasonic wave increases with the increase in elasticity due to polymerization. The percentage of residual acrylamide monomer is estimated using ultraviolet spectrophotometric analysis. The ultrasonic velocity is correlated with the residual monomer concentration

Acridones as inducers of HL-60 cell differentiation.

Science.gov (United States)

Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M; Takemura, Y; Ju-ichi, M; Ito, C; Furukawa, H

1999-03-01

Fifteen acridone alkaloids were examined for their activity of induction of human promyelocytic leukemia cell (HL-60) differentiation. HL-60 cells were differentiated into mature monocyte/macrophage by atalaphyllidine (9), atalaphyllinine (12), and des-N-methylnoracronycine (13). The activities of NBT reduction, nonspecific esterase, and phagocytosis, were induced by 2.5 microM of 9, 12, and 13. After a 4-day treatment, 9, 12, and 13 at 10 microM inhibited clonal proliferation of HL-60 cells by 28, 96, and 63%, respectively. The structure-activity relationship established from the results revealed that hydroxyl group at C-1 and prenyl group at C-2 had an important role.

Ion chromatography for the analysis of salt splitting capacities of cation and anion resin in premixed resin sample

International Nuclear Information System (INIS)

Ghosh, Satinath; Kumar, Rakesh; Tripathy, M.K.; Dhole, K.; Sharma, R.S.; Varde, P.V.

2017-01-01

Mixed bed ion exchange resin is commonly used in various plants including nuclear reactors for the purpose of fine polishing. The analysis of ion exchange capacities of cation and anion resin in resin mixture is therefore an agenda in the context of purchasing of premixed resin from the manufacturer. An ion chromatographic method for assaying ion exchange capacities of pure as well as mixed resin has been optimized. The proposed method in contrast to the conventional ASTM method has been found to be quite encouraging to consider it as an alternate method for the analysis of premixed resin. (author)

Biphenyl liquid crystalline epoxy resin as a low-shrinkage resin-based dental restorative nanocomposite.

Science.gov (United States)

Hsu, Sheng-Hao; Chen, Rung-Shu; Chang, Yuan-Ling; Chen, Min-Huey; Cheng, Kuo-Chung; Su, Wei-Fang

2012-11-01

Low-shrinkage resin-based photocurable liquid crystalline epoxy nanocomposite has been investigated with regard to its application as a dental restoration material. The nanocomposite consists of an organic matrix and an inorganic reinforcing filler. The organic matrix is made of liquid crystalline biphenyl epoxy resin (BP), an epoxy resin consisting of cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (ECH), the photoinitiator 4-octylphenyl phenyliodonium hexafluoroantimonate and the photosensitizer champhorquinone. The inorganic filler is silica nanoparticles (∼70-100 nm). The nanoparticles were modified by an epoxy silane of γ-glycidoxypropyltrimethoxysilane to be compatible with the organic matrix and to chemically bond with the organic matrix after photo curing. By incorporating the BP liquid crystalline (LC) epoxy resin into conventional ECH epoxy resin, the nanocomposite has improved hardness, flexural modulus, water absorption and coefficient of thermal expansion. Although the incorporation of silica filler may dilute the reinforcing effect of crystalline BP, a high silica filler content (∼42 vol.%) was found to increase the physical and chemical properties of the nanocomposite due to the formation of unique microstructures. The microstructure of nanoparticle embedded layers was observed in the nanocomposite using scanning and transmission electron microscopy. This unique microstructure indicates that the crystalline BP and nanoparticles support each other and result in outstanding mechanical properties. The crystalline BP in the LC epoxy resin-based nanocomposite was partially melted during exothermic photopolymerization, and the resin expanded via an order-to-disorder transition. Thus, the post-gelation shrinkage of the LC epoxy resin-based nanocomposite is greatly reduced, ∼50.6% less than in commercialized methacrylate resin-based composites. This LC epoxy nanocomposite demonstrates good physical and chemical properties and good biocompatibility

Overview on resins available in microlithography

International Nuclear Information System (INIS)

Serre, B.; Schue, F.; Montginoul, C.; Giral, L.

1985-01-01

Lithographic equipments using electrons and X radiation are developed. Velocity and resolution requirements fix the nature of the material to irradiate. Circuit making principles are recalled here; resists (organic polymers) are employed for it. The different types of resins and then needed characteristics are reviewed here. In the scope of electron sensitive resins methyl polymethacrylate and derivative and its copolymers (and copolymers of methacrylonitrile) and reticulated copolymers are studied. Polysulfones are also presented (poly(buten-1 sulfone), poly(styrene sulfone), poly(methyl-1 cyclopentene-1 sulfone). The interest in photosensitive resins (such as AZ) as electron sensitive resins is recalled. In the field of negative resins, the polyepoxyds, polystyrene and halogenated derivates from polystyrene (CMS and PCMS), the poly(vinyl-2 naphtalene) and its derivatives (PSTTF) are presented. The X radiation sensitive resins are also reviewed: the methyl polymethacrylate and its halogenated derivates, the acrylic homopolymers and copolymers (example of poly(acrylate of chlorinated alcoyls). The resins developable by plasma are mentioned. At last, for photosensitive resins, the diazide polydiene systems are presented together with systems diazo-2 2H-naphtalenone-1. The systems with salt photolysis are just recalled [fr

Effects of layering technique on the shade of resin overlays and the microhardness of dual cure resin cement

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Hoon-Sang Chang

2014-06-01

Full Text Available The purpose of this study was to assess the color of layered resin overlays and to test the early microhardness of dual cure resin cement (DCRC light cured through the layered resin overlays. Resin overlays of 1.5 mm thickness were fabricated with the A3 shade of Z350 (Group 1L, the A3B and A3E shades of Supreme XT (Group 2L, and the A3, E3, and T1 shades of Sinfony (Group 3L using one, two, and three layers, respectively (n = 7. Each layer of the resin overlays was set in equal thickness. The color of the resin overlays was measured with a colorimeter and compared with an A3 shade resin denture tooth. DCRC was light cured through the resin overlays, and the early microhardness of the DCRC was measured. The ΔE value between the denture tooth and the resin overlays and the Vickers hardness number (VHN of the DCRC were analyzed with one-way ANOVA and Tukey’s HSD test. The color differences were 8.9 ± 0.5, 5.3 ± 1.0, and 7.3 ± 0.5 and the VHNs were 19.4 ± 1.1, 21.1 ± 0.9, and 29.3 ± 0.6 for Groups 1L, 2L, and 3L, respectively. Therefore, to match the designated tooth color of resin inlays and to increase the early microhardness of DCRC, layered resin inlays are more appropriate than single-dentin-layer resin inlays. However, the translucent layer should be used cautiously because the color difference of resin inlays with a translucent layer was affected more than those without a translucent layer.

Differentiation of human-induced pluripotent stem cells into insulin-producing clusters.

Science.gov (United States)

Shaer, Anahita; Azarpira, Negar; Vahdati, Akbar; Karimi, Mohammad Hosein; Shariati, Mehrdad

2015-02-01

In diabetes mellitus type 1, beta cells are mostly destroyed; while in diabetes mellitus type 2, beta cells are reduced by 40% to 60%. We hope that soon, stem cells can be used in diabetes therapy via pancreatic beta cell replacement. Induced pluripotent stem cells are a kind of stem cell taken from an adult somatic cell by "stimulating" certain genes. These induced pluripotent stem cells may be a promising source of cell therapy. This study sought to produce isletlike clusters of insulin-producing cells taken from induced pluripotent stem cells. A human-induced pluripotent stem cell line was induced into isletlike clusters via a 4-step protocol, by adding insulin, transferrin, and selenium (ITS), N2, B27, fibroblast growth factor, and nicotinamide. During differentiation, expression of pancreatic β-cell genes was evaluated by reverse transcriptase-polymerase chain reaction; the morphologic changes of induced pluripotent stem cells toward isletlike clusters were observed by a light microscope. Dithizone staining was used to stain these isletlike clusters. Insulin produced by these clusters was evaluated by radio immunosorbent assay, and the secretion capacity was analyzed with a glucose challenge test. Differentiation was evaluated by analyzing the morphology, dithizone staining, real-time quantitative polymerase chain reaction, and immunocytochemistry. Gene expression of insulin, glucagon, PDX1, NGN3, PAX4, PAX6, NKX6.1, KIR6.2, and GLUT2 were documented by analyzing real-time quantitative polymerase chain reaction. Dithizone-stained cellular clusters were observed after 23 days. The isletlike clusters significantly produced insulin. The isletlike clusters could increase insulin secretion after a glucose challenge test. This work provides a model for studying the differentiation of human-induced pluripotent stem cells to insulin-producing cells.

Antifungal Effect of Henna against Candida albicans Adhered to Acrylic Resin as a Possible Method for Prevention of Denture Stomatitis

Science.gov (United States)

Nawasrah, Amal; AlNimr, Amani; Ali, Aiman A.

2016-01-01

Denture stomatitis is a very common disease affecting the oral mucosa of denture wearers. The aim of this study was to measure the antifungal effect of henna against Candida albicans adhered to acrylic resin as a possible method for prevention of denture stomatitis. One-hundred-eighty acrylic plates were prepared of heat-cured acrylic denture resin. The specimens were divided into six groups of 30 samples each. The first group was only polymer and monomer following the conventional manufacturer instruction for processing complete dentures. The other five groups were processed by adding different concentration of Yamani henna powder (Harazi) to the polymer in a concentration of henna: polymer 1%, 2.5%, 5%, 7.5% and 10%, respectively. Samples were incubated in artificial saliva rich with Candida albicans at 37 °C, and the effect of henna on Candida albicans was evaluated in two different methods: semi-quantitative slide count and a culture-based quantitative assay (quantitative). Variation in the number of live Candida was observed with the increase in the concentration of Yamani henna powder. It was observed that the variation in live Candida, between control group and group B (concentration of Yamani henna powder was 1%), was statistically significant with a p-value of 0.0001. Similarly, variations in live Candida were significant, when the concentration of powder was 7.5% or 10% in contrast with control group and p-values were 0.0001 and 0.001 respectively. Adding henna to acrylic resin denture could be effective in controlling Candida albicans proliferation on the denture surface; however, its effects on the physical properties of acrylic resin denture need further studies. PMID:27223294

Resin for processing radioactive waste water

International Nuclear Information System (INIS)

Onozuka, Teruo; Shindo, Manabu; Kiba, Hideaki; Kubota, Hirohisa; Sawada, Shintaro.

1995-01-01

The present invention concerns an anionic exchange resin having a long service life with less radiation degradation. The resin is an anionic exchange resin in which a trimethyl ammonium group is introduced to a copolymer of 4-bromo-butoxymethyl styrene and divinyl benzene. The resin is excellent in economic performance, and can reduce the frequency for the exchange of cross-linked anionic exchangers. (T.M.)

Resin for processing radioactive waste water

Energy Technology Data Exchange (ETDEWEB)

Onozuka, Teruo; Shindo, Manabu [Tohoku Electric Power Co., Inc., Sendai (Japan); Kiba, Hideaki; Kubota, Hirohisa; Sawada, Shintaro

1995-11-07

The present invention concerns an anionic exchange resin having a long service life with less radiation degradation. The resin is an anionic exchange resin in which a trimethyl ammonium group is introduced to a copolymer of 4-bromo-butoxymethyl styrene and divinyl benzene. The resin is excellent in economic performance, and can reduce the frequency for the exchange of cross-linked anionic exchangers. (T.M.).

The radiation grafting of vinyl monomers to cotton fabrics

International Nuclear Information System (INIS)

Shiraishi, N.; Williams, J.L.; Stannett, V.

1982-01-01

Cobalt 60 γ and electron beam radiation were used to graft diethylphosphatoethyl methacrylate, pure and in 90:10 methanol solution, to cotton cloth. This monomer, with an 11.64% phosphorus content, was especially developed by the Scott Paper Co. to develop fire retardancy. A simple pad and squeeze application followed by direct irradiation under a nitrogen atmosphere was used. Although excess monomer could be removed by washing with water, no solvent for the polymer was found so only the total 'add-ons' could be measured. With 60 Co irradiation, total polymerization was obtained with more than 1 Mrad but with electron beam irradiation only about 50% conversion was obtained even with 10 Mrad. No acceleration in the rates could be achieved with the viscous pure monomer as opposed to in solution. Yields adequate to impart reasonable fire retardancy could, however, be obtained with about 3 Mrad with electrons. No noticeable degradation of the polymer occurred at the doses used. (author)

Radiation curing of mixtures of diallylphthalate prepolymer and vinyl monomer, 9

International Nuclear Information System (INIS)

Gotoda, Masao; Kitada, Yoshinori.

1975-01-01

Radiation curing, mainly by electron beams was studied with mixtures of low molecular weight diallylphthalate prepolymer (DAPsub(p).L) and vinyl monomers with special reference to their workability. Among the vinyl monomers, acrylonitrile gave a solution of low viscosity and methyl acrylate gave a solution of low dose curing. Radiation curing of DAPsub(p).L/vinyl monomer mixtures impregnated in wood was also tried. To obtain uniform wood-polymer composites, γ-irradiation after impregnation at 10 kg/cm 2 was found to be required for thick plate (110 mm), while electron beam irradiation after impregnation at normal pressure was sufficient for thin plate. (author)

Effect of monomer composition on the properties of high temperature polymer concretes

Energy Technology Data Exchange (ETDEWEB)

Zeldin, A.; Kukacka, L.E.; Carciello, N.

1980-01-01

The effects of organic monomer composition on the thermomechanical properties of polymer concrete (PC) containing sand-cement mixtures as an agregate filler were investigated. The effects of various monomer mixtures on compressive strength and hydrolytic stability are discussed. Composites were fabricated in the same way as ordinary concrete, with monomer solutions of various compositions and concentrations used to bind the sand-cement mixture. The compressive strengths of th composites before and after exposure to air and to brine solutions at 240/sup 0/C are discussed.

Discovery of novel inducers of cellular differentiation using HL-60 promyelocytic cells.

Science.gov (United States)

Mata-Greenwood, E; Ito, A; Westenburg, H; Cui, B; Mehta, R G; Kinghorn, A D; Pezzuto, J M

2001-01-01

Non-physiological inducers of terminal differentiation have been used as novel therapies for the prevention and therapy of cancer. We have used cultured HL-60 promyelocytic cells to monitor differentiation, proliferation and cell death events as induced by a large set of extracts derived from plants. Screening of more than 1400 extracts led to the discovery of 34 with potent activity (ED50 Petiveria alliacea, and desmethylrocaglamide from Aglaia ponapensis. Zapotin demonstrated the most favorable biological profile in that induction of differentiation correlated with proliferation arrest, and a lack of cytotoxicity. We conclude that the HL-60 cell model is a useful system for the discovery of novel pharmacophores with potential to suppress the process of carcinogenesis, and that flavonoids may be especially useful in this capacity.

Synthesis and characterization of the monomer 2,2'-dialylbisphenol-A (ABFA) for production of proton exchange membranes based on sulphonated poly(arylene ether sulphone)s reticulated

International Nuclear Information System (INIS)

Souza, Julio C.; Souza, Carlos H.F.B.; Silva, Maria Elisa S.R.; Sousa, Ricardo G.; Freitas, Roberto F.S.; Silva, Claudio Homero F.

2011-01-01

In the present work, a methodology of synthesis and characterization of the monomer 2,2'- dialylbisphenol A was developed, aiming at getting a precursor, with adequate purity, for obtaining cross-linked membranes based on sulfonated poly(arylene ether sulfone)s. The monomer 2,2'- dialylbisphenol A was obtained through Claisen rearrangement of the 2,2-Bis(4-alyloxiphenyl)propane, synthesized from Bisphenol A. All the products and reagents were characterized by Fourier Transform infrared spectroscopy, Thermo-gravimetric analysis and High-performance liquid chromatography. The thermal Claisen rearrangement process was conducted by using Differential Scanning Calorimetry technique, from a factorial experiment planning, with temperature and time being the variables. The above cited techniques were used for monitoring the Claisen rearrangement and for the characterization of the final product. The best results yield an ABFA purity between 85 and 90%. The obtained results suggest that, in the studied range, polymerization and degradation of the monomer ABFA occur, simultaneously to its formation. (author)

Resin acids as the potential growth-affecting component of pine oleoresin

Directory of Open Access Journals (Sweden)

T. J. Wodzicki

2015-01-01

Full Text Available The nonvolatile fraction of the oleoresin of Pinus sihestris L. was found to contain substances which inhibit growth of wheat ceoleoptile and oat mesocotyl sections in standard bioassays. The inhibition is mainly confined to the fraction of resin acids. Among the seven authentic resin acids tested, the effects of dehydroabietic and abietic acids were most sifgnificant. Palustric, pimaric and isopimaric acids were not effective in the wheat coleoptile section straight growth test. None of the substances, in the amounts tested, except for extremely high concentration, exerted an inhibitory effect on natural or IAA-induced elongation of pine hypocotyl sections. Neither was an inhibitory effect discovered in the microbiological test with the Aspergillus niger van Tiegh. The results obtained with pine hypocotyl sections, allow the conclusion that resin acids interfering with the results of standard bioassays are probably not effective as inhibitory factors in the regulation of pine tissue growth.

Perturbation of the Monomer-Monomer Interfaces of the Benzoylformate Decarboxylase Tetramer

Energy Technology Data Exchange (ETDEWEB)

Andrews, Forest H.; Rogers, Megan P.; Paul, Lake N.; McLeish, Michael J. [IUPUI; (Purdue)

2014-08-14

The X-ray structure of benzoylformate decarboxylase (BFDC) from Pseudomonas putida ATCC 12633 shows it to be a tetramer. This was believed to be typical of all thiamin diphosphate-dependent decarboxylases until recently when the structure of KdcA, a branched-chain 2-keto acid decarboxylase from Lactococcus lactis, showed it to be a homodimer. This lent credence to earlier unfolding experiments on pyruvate decarboxylase from Saccharomyces cerevisiae that indicated that it might be active as a dimer. To investigate this possibility in BFDC, we sought to shift the equilibrium toward dimer formation. Point mutations were made in the noncatalytic monomer–monomer interfaces, but these had a minimal effect on both tetramer formation and catalytic activity. Subsequently, the R141E/Y288A/A306F variant was shown by analytical ultracentrifugation to be partially dimeric. It was also found to be catalytically inactive. Further experiments revealed that just two mutations, R141E and A306F, were sufficient to markedly alter the dimer–tetramer equilibrium and to provide an ~450-fold decrease in k_cat. Equilibrium denaturation studies suggested that the residual activity was possibly due to the presence of residual tetramer. The structures of the R141E and A306F variants, determined to <1.5 Å resolution, hinted that disruption of the monomer interfaces will be accompanied by movement of a loop containing Leu109 and Leu110. As these residues contribute to the hydrophobicity of the active site and the correct positioning of the substrate, it seems that tetramer formation may well be critical to the catalytic activity of BFDC.

Correlating cytotoxicity to elution behaviors of composite resins in term of curing kinetic.

Science.gov (United States)

Meng, Junquan; Yang, Huichuan; Cao, Man; Li, Lei; Cai, Qing

2017-09-01

Cytotoxicity of photocurable composite resins is a key issue for their safe use in dental restoration. Curing kinetic and elution behaviors of the composite resin would have decisive effects on its cytotoxicity. In this study, composite resins composed of bisphenol-glycidyl dimethacrylate (Bis-GMA), triethyleneglycol dimethacrylate (TEGDMA), camphorquinone (CQ), N,N-dimethylaminoethyl methacrylate (DMAEMA) and barium glass powders were prepared by setting the photoinitiators CQ/DMAEMA at 0.5wt%, 1wt% or 3wt% of the total weight of Bis-GMA/TEGDMA. The ratio of Bis-GMA/TEGDMA was 6:4, the ratio of CQ/DMAEMA was 1:1, and the incorporated inorganic powder was 75wt%. Then, curing kinetics were studied by using real-time Fourier transform infrared spectroscopy (FTIR) and photo-DSC (differential scanning calorimeter). Elution behaviors in both ethanol solution and deionized water were monitored by using liquid chromatogram/mass spectrometry (LC/MS). Cytotoxicity was evaluated by in vitro culture of L929 fibroblasts. Finally, they were all analyzed and correlated in terms of initiator contents. It was found that the commonly used 0.5wt% of photoinitiators was somewhat insufficient in obtaining composite resin with low cytotoxicity. Copyright © 2017. Published by Elsevier B.V.

In situ polymerization of monomers for polyphenylquinoxaline/graphite

Science.gov (United States)

Serafini, T. T.; Delvigs, P.; Vannucci, R. D.

1973-01-01

Methods currently used to prepare fiber reinforced, high temperature resistant polyphenylquinoxaline (PPQ) composites employ extremely viscous, low solids content solutions of high molecular weight PPQ polymers. An improved approach, described in this report, consists of impregnating the fiber with a solution of the appropriate monomers instead of a solution of previously synthesized high molecular weight polymer. Polymerization of the monomers occurs in situ on the fiber during the solvent removal and curing stages. The in situ polymerization approach greatly simplifies the fabrication of PPQ graphite fiber composites. The use of low viscosity monomeric type solutions facilitates fiber wetting, permits a high solids content, and eliminates the need for prior polymer synthesis.

Bulk-Fill Resin Composites

DEFF Research Database (Denmark)

Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

2015-01-01

the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

[Physical properties of resins for veneer crown. (Part 1) Bending strength of thermosetting methacrylic resins (author's transl)].

Science.gov (United States)

Kashiwada, T

1979-01-01

The physical properties of thermosetting methacrylic resins contain a kind or more than two kinds of cross linking agents were investigated. Knoop hardness and bending strength after drying, water sorption and thermal cycling were listed in table 4 and 5. Hydrophilic resins absorbed water about 3 times as much as hydrophobic resins. The materials contain a small amount of hydrophobic cross linking agents in MMA indicate comparatively excellent properties after drying, water sorption and thermal cycling. Knoop hardness of resins generally reduced by water sorption, especially in the case of the resin contains a large amount of triethylene glycol dimethacrylate.

A comment on water’s structure using monomer fraction data and theories

DEFF Research Database (Denmark)

Liang, Xiaodong; Maribo-Mogensen, Bjørn; Tsivintzelis, Ioannis

2016-01-01

Monomer fraction data for water (and other compounds) can provide useful information about their structure and can be used in “advanced” equations of state, which account explicitly for association phenomena. Recent findings about the performance of association theories in representing the monomer...... fraction of water are reviewed. Three such theories are considered and all of them perform qualitatively similar. They can all represent phase equilibria for water solutions qualitatively well but with parameters which are not in good agreement with Luck’s famous monomer fraction data. While this could set...... the theoretical basis of these theories in doubt, we also show in this work that the findings with these association models are in agreement with a recently presented theory which links monomer fraction to dielectric constants. This new theory, like the three thermodynamic models, predicts more hydrogen bonding...

Curing reaction of bisphenol-A based benzoxazine with cyanate ester resin and the properties of the cured thermosetting resin

Directory of Open Access Journals (Sweden)

H. Kimura

2011-12-01

Full Text Available Curing reaction of bisphenol-A based benzoxazine with cyanate ester resin and the properties of the cured thermosetting resin were investigated. The cure behavior of benzoxazine with cyanate ester resin was monitored by model reaction using nuclear magnetic resonance (NMR. As a result of the model reaction, the ring opening reaction of benzoxazine ring and thermal self-cyclotrimerization of cyanate ester group occurred, and then the phenolic hydoroxyl group generated by the ring opening reaction of benzoxazine ring co-reacted with cyanate ester group. The properties of the cured thermosetting resin were estimated by mechanical properties, electrical resistivity, water resistance and heat resistance. The cured thermosetting resin from benzoxazine and cyanate ester resin showed good heat resistance, high electrical resistivity and high water resistance, compared with the cured thermosetting resin from benzoxazine and epoxy resin.

Removal of radiocesium using cation exchange resin

International Nuclear Information System (INIS)

Morita-Murase, Yuko; Mizumura, Ryosuke; Tachibana, Yoshitaka; Kanazawa, Hideko

2013-01-01

Cation exchange resins (calcium polystyrene sulfonate, Ca-resin and sodium polystyrene sulfonate, Na-resin) have been used as agents to improve hyperkerlemia. For removing 137 Cs from the human body, the adsorption ability of the resin for 137 Cs was examined and evaluated. Resin (0.03 g) and 137 Cs (ca.1 kBq) were introduced into 3 mL of water, the Japanese Pharmacopoeia 1st fluid for a dissolution test (pH 1.2) and 2nd fluid (pH 6.8), respectively, and shaken. After 1-3 hours, the 137 Cs adsorption (%) of Na-resin was 99% in water, 60% in a pH 1.2 fluid and, 66% in a pH 6.8 fluid. By adding potassium, the 137 Cs adsorption (%) of Ca-resin was reduced. However, the 137 Cs adsorption (%) of Na-resin was almost unchanged. These results show that both resins have adsorption ability for 137 Cs in the stomach and the intestines. Therefore, the proposed method will be an effective means in the case of a radiological emergency due to 137 Cs. (author)

Vogel-Fulcher dependence of relaxation rates in a nematic monomer and elastomer

Science.gov (United States)

Shenoy, D.; Filippov, S.; Aliev, F.; Keller, P.; Thomsen, D.; Ratna, B.

2000-12-01

Dielectric relaxation spectroscopy is used to study the relaxation processes in a nematic monomer and the corresponding cross-linked polymer nematic liquid crystal (elastomer). In the frequency window 10 mHz to 2 GHz the monomer liquid crystal shows a single relaxation whereas the polymer exhibits three relaxation processes, two of which are quantitatively analyzed. The temperature dependence of relaxation times in both the monomer and polymer follows a Vogel-Fulcher behavior. The relaxation processes are identified with specific molecular motions and activation energies are calculated in a linear approximation for comparison with literature data.

Frankincense essential oil prepared from hydrodistillation of Boswellia sacra gum resins induces human pancreatic cancer cell death in cultures and in a xenograft murine model

Science.gov (United States)

2012-01-01

Background Regardless of the availability of therapeutic options, the overall 5-year survival for patients diagnosed with pancreatic cancer remains less than 5%. Gum resins from Boswellia species, also known as frankincense, have been used as a major ingredient in Ayurvedic and Chinese medicine to treat a variety of health-related conditions. Both frankincense chemical extracts and essential oil prepared from Boswellia species gum resins exhibit anti-neoplastic activity, and have been investigated as potential anti-cancer agents. The goals of this study are to identify optimal condition for preparing frankincense essential oil that possesses potent anti-tumor activity, and to evaluate the activity in both cultured human pancreatic cancer cells and a xenograft mouse cancer model. Methods Boswellia sacra gum resins were hydrodistilled at 78°C; and essential oil distillate fractions were collected at different durations (Fraction I at 0–2 h, Fraction II at 8–10 h, and Fraction III at 11–12 h). Hydrodistillation of the second half of gum resins was performed at 100°C; and distillate was collected at 11–12 h (Fraction IV). Chemical compositions were identified by gas chromatography–mass spectrometry (GC-MS); and total boswellic acids contents were quantified by high-performance liquid chromatography (HPLC). Frankincense essential oil-modulated pancreatic tumor cell viability and cytotoxicity were determined by colorimetric assays. Levels of apoptotic markers, signaling molecules, and cell cycle regulators expression were characterized by Western blot analysis. A heterotopic (subcutaneous) human pancreatic cancer xenograft nude mouse model was used to evaluate anti-tumor capability of Fraction IV frankincense essential oil in vivo. Frankincense essential oil-induced tumor cytostatic and cytotoxic activities in animals were assessed by immunohistochemistry. Results Longer duration and higher temperature hydrodistillation produced more abundant high molecular

Novel silica-based ion exchange resin

Energy Technology Data Exchange (ETDEWEB)

NONE

1997-11-01

Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

Measurement of opalescence of resin composites.

Science.gov (United States)

Lee, Yong-Keun; Lu, Huan; Powers, John M

2005-11-01

Opalescence is an optical property, where there is light scattering of the shorter wavelengths of the visible spectrum, giving the material a bluish appearance under reflected light and an orange/brown appearance under transmitted light. The objective of this study was to determine the opalescence of resin composites with a color measuring spectrophotometer. Colors of A2 and enamel or translucent shades of four resin composites and of an unfilled resin measured in the reflectance and transmittance modes were compared, and the opalescence parameter (OP) was calculated as the difference in blue-yellow coordinate (Deltab*) and red-green parameter (Deltaa*) between the reflected and transmitted colors of 1-mm thick specimens. The masking effect was calculated as the color difference between the color of a black background and the color of specimen over the black background. The range of OP in resin composites was 5.7-23.7, which was higher than that of the unfilled resin. However, there were significant differences among the brands and shades of the resin composites. Opalescence varied by brand and shade of the resin composites, and contributed to the masking of background color along with translucency parameter. Some of the resin composites actually displayed opalescence.

Disposal of bead ion exchange resin wastes

International Nuclear Information System (INIS)

Gay, R.L.; Granthan, L.F.

1985-01-01

Bead ion exchange resin wastes are disposed of by a process which involves spray-drying a bead ion exchange resin waste in order to remove substantially all of the water present in such waste, including the water on the surface of the ion exchange resin beads and the water inside the ion exchange resin beads. The resulting dried ion exchange resin beads can then be solidified in a suitable solid matrix-forming material, such as a polymer, which solidifies to contain the dried ion exchange resin beads in a solid monolith suitable for disposal by burial or other conventional means

DNA-damage-induced differentiation of leukaemic cells as an anti-cancer barrier.

Science.gov (United States)

Santos, Margarida A; Faryabi, Robert B; Ergen, Aysegul V; Day, Amanda M; Malhowski, Amy; Canela, Andres; Onozawa, Masahiro; Lee, Ji-Eun; Callen, Elsa; Gutierrez-Martinez, Paula; Chen, Hua-Tang; Wong, Nancy; Finkel, Nadia; Deshpande, Aniruddha; Sharrow, Susan; Rossi, Derrick J; Ito, Keisuke; Ge, Kai; Aplan, Peter D; Armstrong, Scott A; Nussenzweig, André

2014-10-02

Self-renewal is the hallmark feature both of normal stem cells and cancer stem cells. Since the regenerative capacity of normal haematopoietic stem cells is limited by the accumulation of reactive oxygen species and DNA double-strand breaks, we speculated that DNA damage might also constrain leukaemic self-renewal and malignant haematopoiesis. Here we show that the histone methyl-transferase MLL4, a suppressor of B-cell lymphoma, is required for stem-cell activity and an aggressive form of acute myeloid leukaemia harbouring the MLL-AF9 oncogene. Deletion of MLL4 enhances myelopoiesis and myeloid differentiation of leukaemic blasts, which protects mice from death related to acute myeloid leukaemia. MLL4 exerts its function by regulating transcriptional programs associated with the antioxidant response. Addition of reactive oxygen species scavengers or ectopic expression of FOXO3 protects MLL4(-/-) MLL-AF9 cells from DNA damage and inhibits myeloid maturation. Similar to MLL4 deficiency, loss of ATM or BRCA1 sensitizes transformed cells to differentiation, suggesting that myeloid differentiation is promoted by loss of genome integrity. Indeed, we show that restriction-enzyme-induced double-strand breaks are sufficient to induce differentiation of MLL-AF9 blasts, which requires cyclin-dependent kinase inhibitor p21(Cip1) (Cdkn1a) activity. In summary, we have uncovered an unexpected tumour-promoting role of genome guardians in enforcing the oncogene-induced differentiation blockade in acute myeloid leukaemia.

Curing kinetics of alkyd/melamine resin mixtures

Directory of Open Access Journals (Sweden)

Jovičić Mirjana C.

2009-01-01

Full Text Available Alkyd resins are the most popular and useful synthetic resins applied as the binder in protective coatings. Frequently they are not used alone but are modified with other synthetic resins in the manufacture of the coatings. An alkyd/melamine resin mixture is the usual composition for the preparation of coating called 'baking enamel' and it is cured through functional groups of resins at high temperatures. In this paper, curing kinetics of alkyd resins based on castor oil and dehydrated castor oil with melamine resin, has been studied by DSC method with programmed heating and in isothermal mode. The results determined from dynamic DSC curves were mathematically transformed using the Ozawa isoconversional method for obtaining the isothermal data. These results, degree of curing versus time, are in good agreement with those determined by the isothermal DSC experiments. By applying the Ozawa method it is possible to calculate the isothermal kinetic parameters for the alkyd/melamine resin mixtures curing using only calorimetric data obtained by dynamic DSC runs. Depending on the alkyd resin type and ratio in mixtures the values of activation energies of curing process of resin mixtures are from 51.3 to 114 kJ mol-1. The rate constant of curing increases with increasing the content of melamine resin in the mixture and with curing temperature. The reaction order varies from 1.12 to 1.37 for alkyd based on dehydrated castor oil/melamine resin mixtures and from 1.74 to 2.03 for mixtures with alkyd based on castor oil. Based on the results obtained, we propose that dehydrated castor oil alkyd/melamine resin mixtures can be used in practice (curing temperatures from 120 to 160°C.

Chronic Dermal Toxicity of Epoxy Resins I. Skin Carcinogenic Potency and General Toxicity

Energy Technology Data Exchange (ETDEWEB)

Holland, J.M.

2001-01-16

Epoxy resins are a diverse class of chemicals that differ in structure, physical properties, and, presumably, biological activity. The purpose of these experiments was to compare the chronic dermal toxicity and carcinogenicity of selected commercial epoxy resins and to determine the potential for positive synergistic carcinogenic interactions between different resins. This work is an extension and continuation of a Department of Energy sponsored program to evaluate epoxy resins for potential occupational health risks. The materials examined were chosen on the basis of their interest to the U.S. government. They are representative of the manufacturer's production at the time, and therefore the data are completely valid only for the specific production period. Results of the experimental exposures will be reported in two parts. This report describes the test materials, their chemical and physical characteristics and the experimental design. General (systemic) toxicity will be evaluated and the skin carcinogenicity of the materials compared. A subsequent report will provide morphological descriptions of skin and significant internal pathology induced by the various treatments.

Role of alpha- and beta-adrenergic receptors in cardiomyocyte differentiation from murine-induced pluripotent stem cells.

Science.gov (United States)

Li, Xiao-Li; Zeng, Di; Chen, Yan; Ding, Lu; Li, Wen-Ju; Wei, Ting; Ou, Dong-Bo; Yan, Song; Wang, Bin; Zheng, Qiang-Sun

2017-02-01

Induced pluripotent stem cell (iPSC)-derived cardiomyocytes are a promising source of cells for regenerative heart disease therapies, but progress towards their use has been limited by their low differentiation efficiency and high cellular heterogeneity. Previous studies have demonstrated expression of adrenergic receptors (ARs) in stem cells after differentiation; however, roles of ARs in fate specification of stem cells, particularly in cardiomyocyte differentiation and development, have not been characterized. Murine-induced pluripotent stem cells (miPSCs) were cultured in hanging drops to form embryoid bodies, cells of which were then differentiated into cardiomyocytes. To determine whether ARs regulated miPSC differentiation into cardiac lineages, effects of the AR agonist, epinephrine (EPI), on miPSC differentiation and underlying signalling mechanisms, were evaluated. Treatment with EPI, robustly enhanced miPSC cardiac differentiation, as indicated by increased expression levels of cardiac-specific markers, GATA4, Nkx2.5 and Tnnt2. Although β-AR signalling is the foremost signalling pathway in cardiomyocytes, EPI-enhanced cardiac differentiation depended more on α-AR signalling than β-AR signalling. In addition, selective activation of α 1 -AR signalling with specific agonists induced vigorous cardiomyocyte differentiation, whereas selective activation of α 2 - or β-AR signalling induced no or less differentiation, respectively. EPI- and α 1 -AR-dependent cardiomyocyte differentiation from miPSCs occurred through specific promotion of CPC proliferation via the MEK-ERK1/2 pathway and regulation of miPS cell-cycle progression. These results demonstrate that activation of ARs, particularly of α 1 -ARs, promoted miPSC differentiation into cardiac lineages via MEK-ERK1/2 signalling. © 2016 John Wiley & Sons Ltd.

Valve seat pores sealed with thermosetting monomer

Science.gov (United States)

Olmore, A. B.

1966-01-01

Hard anodic coating provides a smooth wear resistant value seating surface on a cast aluminum alloy valve body. Vacuum impregnation with a thermosetting monomer, diallyl phthalate, seals the pores on the coating to prevent galvanic corrosion.

[miRNA profile of the human dental pulp cells during odontoblast differentiation induced by BMP-2].

Science.gov (United States)

Bao, Li-Rong; Zhao, Wen-Qing; Lin, Tian; Lu, Yan-Ling; Wu, Yu

2017-10-01

To screen and verify the differentially expressed microRNAs (miRNAs) during the differentiation of human dental pulp cells (hDPCs) to odontoblasts induced by BMP-2. The isolated hDPCs were cultured in vitro and induced by BMP-2. The levels of ALP, DMP-1 and DSPP were quantified by quantitative real-time polymerase chain reaction (qRT-PCR). The potential characteristics of hDPCs were investigated by miRNA microarray and highly expressed miRNAs were selected with bio-information software for predicting target genes and their biological functions. Then the results were validated using qRT-PCR analysis for the selected miRNAs. Statistical analysis was performed using SPSS 18.0 software package. The expression of ALP, DSPP, and DMP-1 showed significantly higher levels in BMP-2 induced groups compared to the control group(Pfunction(33%), while the function of other 0.2% genes remained unknown. This study identified differential expression of miRNAs in BMP-2-induced odontoblastic differentiation of hDPCs, thus contributing to further investigations of regulatory mechanisms and biological effect of target genes in BMP-2-induced odontoblastic differentiation of hDPCs.

Spray drying of bead resins: feasibility tests

International Nuclear Information System (INIS)

Gay, R.L.; Grantham, L.F.; Jones, L.J.

1984-01-01

Rockwell International has developed a volume reduction system for low-level reactor wastes based on drying the wastes in a heated-air spray dryer. The drying of slurries of sodium sulfate, boric acid, and powdered ion exchange resins was demonstrated in previous tests. The drying of bead ion exchange resins can be especially difficult due to the relatively large size of bead resins (about 500 to 800 microns) and their natural affinity for water. This water becomes part of the pore structure of the resins and normally comprises 50 t 60 wt % of the resin weight. A 76-cm-diameter spray dryer was used for feasibility tests of spray drying of cation and anion bead resins. These resins were fed to the dryer in the as-received form (similar to dewatered resins) and as slurries. A dry, free-flowing product was produced in all the tests. The volume of the spray-dried product was one-half to one-third the volume of the as-received material. An economic analysis was made of the potential cost savings that can be achieved using the Rockwel spray dryer system. In-plant costs, transportation costs, and burial costs of spray-dried resins were compared to similar costs for disposal of dewatered resins. A typical utility producing 170 m 3 (6,000 ft 3 ) per year of dewatered resins can save $600,000 to $700,000 per year using this volume reduction system

Effect of repair resin type and surface treatment on the repair strength of polyamide denture base resin.

Science.gov (United States)

Gundogdu, Mustafa; Yanikoglu, Nuran; Bayindir, Funda; Ciftci, Hilal

2015-01-01

The purpose of the present study was to evaluate the effects of different repair resins and surface treatments on the repair strength of a polyamide denture base material. Polyamide resin specimens were prepared and divided into nine groups according to the surface treatments and repair materials. The flexural strengths were measured with a 3-point bending test. Data were analyzed with a 2-way analysis of variance, and the post-hoc Tukey test (α=0.05). The effects of the surface treatments on the surface of the polyamide resin were examined using scanning electron microscopy. The repair resins and surface treatments significantly affected the repair strength of the polyamide denture base material (p0.05). The flexural strength of the specimens repaired with the polyamide resin was significantly higher than that of those repaired with the heat-polymerized and autopolymerizing acrylic resins.

Erythroid differentiation of human induced pluripotent stem cells is independent of donor cell type of origin.

Science.gov (United States)

Dorn, Isabel; Klich, Katharina; Arauzo-Bravo, Marcos J; Radstaak, Martina; Santourlidis, Simeon; Ghanjati, Foued; Radke, Teja F; Psathaki, Olympia E; Hargus, Gunnar; Kramer, Jan; Einhaus, Martin; Kim, Jeong Beom; Kögler, Gesine; Wernet, Peter; Schöler, Hans R; Schlenke, Peter; Zaehres, Holm

2015-01-01

Epigenetic memory in induced pluripotent stem cells, which is related to the somatic cell type of origin of the stem cells, might lead to variations in the differentiation capacities of the pluripotent stem cells. In this context, induced pluripotent stem cells from human CD34(+) hematopoietic stem cells might be more suitable for hematopoietic differentiation than the commonly used fibroblast-derived induced pluripotent stem cells. To investigate the influence of an epigenetic memory on the ex vivo expansion of induced pluripotent stem cells into erythroid cells, we compared induced pluripotent stem cells from human neural stem cells and human cord blood-derived CD34(+) hematopoietic stem cells and evaluated their potential for differentiation into hematopoietic progenitor and mature red blood cells. Although genome-wide DNA methylation profiling at all promoter regions demonstrates that the epigenetic memory of induced pluripotent stem cells is influenced by the somatic cell type of origin of the stem cells, we found a similar hematopoietic induction potential and erythroid differentiation pattern of induced pluripotent stem cells of different somatic cell origin. All human induced pluripotent stem cell lines showed terminal maturation into normoblasts and enucleated reticulocytes, producing predominantly fetal hemoglobin. Differences were only observed in the growth rate of erythroid cells, which was slightly higher in the induced pluripotent stem cells derived from CD34(+) hematopoietic stem cells. More detailed methylation analysis of the hematopoietic and erythroid promoters identified similar CpG methylation levels in the induced pluripotent stem cell lines derived from CD34(+) cells and those derived from neural stem cells, which confirms their comparable erythroid differentiation potential. Copyright© Ferrata Storti Foundation.

Synaptic network activity induces neuronal differentiation of adult hippocampal precursor cells through BDNF signaling

Directory of Open Access Journals (Sweden)

Harish Babu

2009-09-01

Full Text Available Adult hippocampal neurogenesis is regulated by activity. But how do neural precursor cells in the hippocampus respond to surrounding network activity and translate increased neural activity into a developmental program? Here we show that long-term potential (LTP-like synaptic activity within a cellular network of mature hippocampal neurons promotes neuronal differentiation of newly generated cells. In co-cultures of precursor cells with primary hippocampal neurons, LTP-like synaptic plasticity induced by addition of glycine in Mg2+-free media for 5 min, produced synchronous network activity and subsequently increased synaptic strength between neurons. Furthermore, this synchronous network activity led to a significant increase in neuronal differentiation from the co-cultured neural precursor cells. When applied directly to precursor cells, glycine and Mg2+-free solution did not induce neuronal differentiation. Synaptic plasticity-induced neuronal differentiation of precursor cells was observed in the presence of GABAergic neurotransmission blockers but was dependent on NMDA-mediated Ca2+ influx. Most importantly, neuronal differentiation required the release of brain-derived neurotrophic factor (BDNF from the underlying substrate hippocampal neurons as well as TrkB receptor phosphorylation in precursor cells. This suggests that activity-dependent stem cell differentiation within the hippocampal network is mediated via synaptically evoked BDNF signaling.

Solidification of ion exchange resin wastes

International Nuclear Information System (INIS)

1982-08-01

Solidification media investigated included portland type I, portland type III and high alumina cements, a proprietary gypsum-based polymer modified cement, and a vinyl ester-styrene thermosetting plastic. Samples formulated with hydraulic cement were analyzed to investigate the effects of resin type, resin loading, waste-to-cement ratio, and water-to-cement ratio. The solidification of cation resin wastes with portland cement was characterized by excessive swelling and cracking of waste forms, both after curing and during immersion testing. Mixed bed resin waste formulations were limited by their cation component. Additives to improve the mechanical properties of portland cement-ion exchange resin waste forms were evaluated. High alumina cement formulations dislayed a resistance to deterioration of mechanical integrity during immersion testing, thus providing a significant advantage over portland cements for the solidification of resin wastes. Properties of cement-ion exchange resin waste forms were examined. An experiment was conducted to study the leachability of 137 Cs, 85 Sr, and 60 Co from resins modified in portland type III and high alumina cements. The cumulative 137 Cs fraction release was at least an order of magnitude greater than that of either 85 Sr or 60 Co. Release rates of 137 Cs in high alumina cement were greater than those in portland III cement by a factor of two.Compressive strength and leach testing were conducted for resin wastes solidified with polymer-modified gypsum based cement. 137 Cs, 85 Sr, and 60 Co fraction releases were about one, two and three orders of magnitude higher, respectively, than in equivalent portland type III cement formulations. As much as 28.6 wt % dry ion exchange resin was successfully solidified using vinyl ester-styrene compared with a maximum of 25 wt % in both portland and gypsum-based cement

Method for regenerating magnetic polyamine-epichlorohydrin resin

Science.gov (United States)

Kochen, Robert L.; Navratil, James D.

1997-07-29

Magnetic polymer resins capable of efficient removal of actinides and heavy metals from contaminated water are disclosed together with methods for making, using, and regenerating them. The resins comprise polyamine-epichlorohydrin resin beads with ferrites attached to the surfaces of the beads. Markedly improved water decontamination is demonstrated using these magnetic polymer resins of the invention in the presence of a magnetic field, as compared with water decontamination methods employing ordinary ion exchange resins or ferrites taken separately.

Interpenetrating network ceramic-resin composite dental restorative materials.

Science.gov (United States)

Swain, M V; Coldea, A; Bilkhair, A; Guess, P C

2016-01-01

This paper investigates the structure and some properties of resin infiltrated ceramic network structure materials suitable for CAD/CAM dental restorative applications. Initially the basis of interpenetrating network materials is defined along with placing them into a materials science perspective. This involves identifying potential advantages of such structures beyond that of the individual materials or simple mixing of the components. Observations from a number of recently published papers on this class of materials are summarized. These include the strength, fracture toughness, hardness and damage tolerance, namely to pointed and blunt (spherical) indentation as well as to burr adjustment. In addition a summary of recent results of crowns subjected to simulated clinical conditions using a chewing simulator are presented. These results are rationalized on the basis of existing theoretical considerations. The currently available ceramic-resin IPN material for clinical application is softer, exhibits comparable strength and fracture toughness but with substantial R-curve behavior, has lower E modulus and is more damage tolerant than existing glass-ceramic materials. Chewing simulation observations with crowns of this material indicate that it appears to be more resistant to sliding/impact induced cracking although its overall contact induced breakage load is modest. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Handling sticky resin by stingless bees (Hymenoptera, Apidae

Directory of Open Access Journals (Sweden)

Markus Gastauer

2011-06-01

Full Text Available For their nest defense, stingless bees (Meliponini collect plant resins which they stick on intruders like ants or cleptobiotic robber bees causing their immobilization. The aim of this article is to identify all parts of stingless bee workers contacting these sticky resins. Of special interest are those body parts with anti-adhesive properties to resin, where it can be removed without residues. For that, extensive behavioral observations during foraging flight, handling and application of the resin have been carried out. When handling the resin, all tarsi touch the resin while walking above it. For transportation from plants to the nest during foraging flight, the resin is packed to the corbicula via tarsi and basitarsi of front and middle legs. Once stuck to the resin or after the corbicula had been unloaded, the bee's legs have to be cleaned thoroughly. Only the tips of the mandibles, that form, cut and apply the sticky resin, seem to have at least temporarily resin-rejecting properties.

Microshear bond strength of composite resins to enamel and porcelain substrates utilizing unfilled versus filled resins.

Science.gov (United States)

Najafi-Abrandabadi, Ahmad; Najafi-Abrandabadi, Siamak; Ghasemi, Amir; Kotick, Philip G

2014-11-01

Failures such as marginal discoloration and composite chipping are still the problems of tooth-colored restorations on the substrate of enamel and porcelain, which some of these problems are consequently as a result of failures in the bonding layer. Using filled resin has been recently introduced to increase the bond strength of this layer. The aim of this study was to compare the microshear bond strength (μ-SBS) of composite resins to enamel incubated in periods of 24 h and 9 months and porcelain with unfilled resin and flowable composites (filled resin). In this in vitro study, two groups of 75 enamel samples with different storage times (24 h and 9 months) and a group of 75 porcelain samples were used. They were divided into 5 experimental groups of 15 samples in each. Composite cylinders in tygon tubes were bonded on the surface of acid-etched enamel and pretreated porcelain. Wave, Wave MV, Wave HV, Grandioflow and Margin Bond were used as bonding agents. The μ-SBS was measured at the speed of 1.0 mm/min. The bond strengths were analyzed with one-way analysis of variance (ANOVA) test followed by Tukey test. P composites (filled resins) can be used instead of unfilled resins in bonding composite resins to enamel and porcelain substrates.

Commercial Ion Exchange Resin Vitrification Studies

International Nuclear Information System (INIS)

Cicero-Herman, C.A

2002-01-01

In the nuclear industry, ion exchange resins are used for purification of aqueous streams. The major contaminants of the resins are usually the radioactive materials that are removed from the aqueous streams. The use of the ion exchange resins creates a waste stream that can be very high in both organic and radioactive constituents. Therefore, disposal of the spent resin often becomes an economic problem because of the large volumes of resin produced and the relatively few technologies that are capable of economically stabilizing this waste. Vitrification of this waste stream presents a reasonable disposal alternative because of its inherent destruction capabilities, the volume reductions obtainable, and the durable product that it produces

Statins activate GATA-6 and induce differentiated vascular smooth muscle cells

International Nuclear Information System (INIS)

Wada, Hiromichi; Abe, Mitsuru; Ono, Koh; Morimoto, Tatsuya; Kawamura, Teruhisa; Takaya, Tomohide; Satoh, Noriko; Fujita, Masatoshi; Kita, Toru; Shimatsu, Akira; Hasegawa, Koji

2008-01-01

The beneficial effects of 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) beyond cholesterol lowering involve their direct actions on vascular smooth muscle cells (VSMCs). However, the effects of statins on phenotypic modulation of VSMCs are unknown. We herein show that simvastatin (Sm) and atorvastatin (At) inhibited DNA synthesis in human aortic VSMCs dose-dependently, while cell toxicity was not observed below the concentration of 1 μM of Sm or 100 nM of At. Stimulating proliferative VSMCs with Sm or At induced the expression of SM-α-actin and SM-MHC, highly specific markers of differentiated phenotype. Sm up-regulated the binding activity of GATA-6 to SM-MHC GATA site and activated the transfected SM-MHC promoter in proliferative VSMCs, while mutating the GATA-6 binding site abolished this activation. Geranylgeranylpyrophosphate (10 μM), an inhibitor of Rho family proteins, abolished the statin-mediated induction of the differentiated phenotype in VSMCs. These findings suggest that statins activate GATA-6 and induce differentiated VSMCs

Statins activate GATA-6 and induce differentiated vascular smooth muscle cells