Acrylic Resins ; chemistry ; Composite Resins ; chemistry ; Dental Research ; Dental Stress Analysis ; Polymerization ; Polyurethanes ; chemistry

OBJECTIVETo analyze the color parameters and translucency of four frequently-used veneer materials.

METHODSForty disc specimens[(1.00±0.01) mm in thickness, 10 mm in diameter] were fabricated according to the manufacturer's instructions with IPS Empress(®) CAD[A2, high translucency (HT)], IPS e.max(®) Press(A2, HT), IPS e.max(®) CAD (A2, HT) and VITABLOCS(®) Mark II (A2) respectively and were divided into Groups A, B, C, D. All of the specimens were ground and polished on a grinding machine. Then color parameters (L*, a*, b*) and transmittance (τ) were measured using spectrocolorimeter and transmissivity testing device. The color parameters of the specimens were compared to the color parameters of A2 shade of Ivoclar Vivadent A-D shade guide. The data were analyzed with one-way analysis of variance (ANOVA), and mean values were compared by the Tukey's test (α = 0.05).

RESULTSThere was no statistical difference between the color parameters L*, a*, b* and C*ab of Group A and Group D (P > 0.05). But the color parameters of those two ceramic materials were statistically different from the color parameters of Group B and Group C (P < 0.05). There was no statistical difference between color parameters b* and C*ab of Group B and Group C(P > 0.05). However, the color parameters L* and a* of the two materials were statistically different(P < 0.05). The color differences (ΔE) between Group A, B, C, D and standard A2 were 6.05±0.12, 5.11±0.27, 3.73±0.27, 6.30±0.38 respectively. The transmittances of Group A, B, C, D were (29.69±0.31)%, (25.83±0.36) %, (28.92±0.47)% and (26.94±0.33)% respectively.

CONCLUSIONSThe color parameters of these four materials are different. Their transmittance are relatively high but statistically different. The color difference (ΔE) between IPS e.max(®) CAD (A2, HT) and standard A2 is lowest among all the groups.

Acrylic Resins ; chemistry ; Ceramics ; chemistry ; Color ; Composite Resins ; chemistry ; Dental Porcelain ; chemistry ; Dental Veneers ; Optical Phenomena ; Polyurethanes ; chemistry

OBJECTIVETo investigate the preparation method of polystyrene core-poly (acrylamide-acrylic acid) shell fluorescent microspheres.

METHODSThe polystyrene core-poly (acrylamide-acrylic acid) shell (P-(St-co-AAM)) fluorescent microspheres were prepared using fluorescent microspheres as the core and acrylamide/acrylic as polymerization monomer. Reaction conditions affecting the morphology of core-shell structure including feeding mode, initiator, cross linker, pH, concentration and swelling were studied.

RESULTFluorescent microscopy showed that the relatively uniform particle sizes were distributed in a range of 7-8 μm. Fourier transform infra-red spectroscopy (FT-IR) proved the existence of poly (acrylamide-acrylic acid) shell and amide group on the surface. The optimal conditions for seeding polymerization: azobisisobutyronitrile was used as the initiator in the absence of cross linker, after a 40 h swelling treatment by using alcohol with the appropriate reaction temperature (70 degree), reaction time (3 h) and pH(6-7). The average dispersion and stability were 25.14 % and 90.21%, respectively. The fluorescein release percentage was kept stable at approximately 30% after 40 h.

CONCLUSIONThe fluorescent microspheres prepared by this method have core-shell structure and satisfactory fluorescence properties with good dispersion and stability.

Acrylates ; chemistry ; Acrylic Resins ; chemistry ; Fluorescein ; chemistry ; Microspheres ; Polymerization ; Polystyrenes ; chemistry

Polyelectrolyte with a large number of cations or anions could precipitate the oppositely charged proteins to form polyelectrolyte-protein complexes, which then aggregated to form larger particles via electrostatic attraction or hydrophobic interaction. The precipitation was affected by the molecular weight and concentration of the polyelectrolyte as well as the ionic strength and pH of the solution. The use of precipitation is an efficient method for selective separation of proteins from crude biological mixtures in the downstream processes of bioengineering.
Acrylic Resins ; chemistry ; Chemical Precipitation ; Electrolytes ; chemistry ; Polyethyleneimine ; chemistry ; Protein Binding ; Proteins ; isolation & purification

Poly-N-isopropylacrylamide (PNIPAAm) is a new kind of intelligent material. It shows favorable thermo sensitivity because of the structure of hydrophilic acrylamino and hydrophobic isopropyl. PNIPAAm also shows good biocompatibility and non-toxicity. All the characters as above make it an ideal extra cellular matrix material for tissue engineering. This paper reviews its application in tissue engineering.
Acrylamides ; chemistry ; Acrylic Resins ; Animals ; Biocompatible Materials ; Hot Temperature ; Humans ; Polymers ; chemistry ; Tissue Engineering ; Tissue Scaffolds

Prohibited substances in cosmetics refer to substances which must not be among the raw material ingredients of cosmetic products. These substances are absorbed mostly through skin, as well as via lung and gastrointestinal tract. Polyacrylamide is ubiquitously used in industry and its decomposition residue acrylamide (ACR) easily finds its way into cosmetic products. ACR can either be oxidized to epoxide glycidamide or conjugated with glutathione, hemoglobin or DNA; ultimately it is excreted in urine. ACR causes neurotoxicity, reproductive toxicity and tumors in rodents. Occupational exposure to ACR causes neurotoxicity in humans; however, epidemiological evidence have not unambiguously answered the question of whether ACR exposure can increase cancer risk for humans.
Acrylamide ; metabolism ; pharmacokinetics ; toxicity ; Acrylic Resins ; chemistry ; China ; Cosmetics ; chemistry ; Humans

The objective of this research is to evaluate the effects of different silane coupling agents on the bond strength between Ceramco3 opaque porcelain and indirect composite resin. Five groups of Co-Cr metal alloy substrates were fabricated according to manufacturer's instruction. The surface of metal alloy with a layer of dental opaque porcelain was heated by fire. After the surface of opaque porcelain was etched, five different surface treatments, i.e. RelyX Ceramic Primer (RCP), Porcelain Bond Activator and SE Bond Primer (mixed with a proportion of 1:1) (PBA), Shofu Porcelain Primer (SPP), SE bond primer (SEP), and no primer treatment (as a control group), were used to combine P60 and opaque porcelain along with resin cement. Shear bond strength of specimens was tested in a universal testing machine. The failure modes of specimens in all groups were observed and classified into four types. Selected specimens were subjected to scanning electron microscope and energy disperse spectroscopy to reveal the relief of the fracture surface and to confirm the failure mode of different types. The experimental results showed that the values of the tested items in all the tested groups were higher than that in the control group. Group PBA exhibited the highest value [(37.52 +/- 2.14) MPa] and this suggested a fact that all of the specimens in group PBA revealed combined failures (failure occurred in metal-porcelain combined surface and within opaque porcelain). Group SPP and RCP showed higher values than SEP (P < 0.05) and most specimens of SPP and RCP performed combined failures (failure occurred in bond surface and within opaque porcelain or composite resin) while all the specimens in group SEP and control group revealed adhesive failures. Conclusions could be drawn that silane coupling agents could reinforce the bond strength of dental composite resin to metal-opaque porcelain substrate. The bond strength between dental composite resin and dental opaque porcelain could meet the clinical requirements.
Acrylic Resins ; chemistry ; Ceramics ; chemistry ; Composite Resins ; chemistry ; Dental Bonding ; Dental Porcelain ; chemistry ; Humans ; Polyurethanes ; chemistry ; Resin Cements ; chemistry ; Silanes ; chemistry

OBJECTIVETo prepare the cross-linked chitosan/poly(acrylic acid)/poly (ethylene oxide) nanofibrous membrance loaded with pseudo-ginseng and to determine its characteristics.

METHODSPseudo-ginseng entrapped in chitosan, poly (acrylic acid), poly (ethylene oxide) nanofibrous membrane loaded with pseudo-ginseng was prepared by electrospinning and thermal treatment method. The surface morphology of fiber membrane was observed by scanning electron microscopy and the chemical structures were characterized by infrared spectroscopy; the thermal decomposition temperature was analyzed by the thermogravimetric analysis. UV-Vis spectra were used to evaluate the in vitro release properties.

RESULTSThe average diameter of the prepared nanofibrous particles was (181 ± 71) nm. The tensile strength of fiber membrane increased by 35.3% and the decomposition temperature increased from 197℃ to 208℃ after crosslinking. Compared with casting film, the structure of fiber membrane increased the release rate and the overall amount of active components from pseudo-ginseng.

CONCLUSIONThe preparation of chitosan fiber loaded with pseudo-ginseng is simple and the dispersion of pseudo-ginseng is homogeneous. This fibrous pseudo-ginseng exhibited good release performance, providing a new Chinese medicine formulation.

Acrylic Resins ; chemistry ; Chitosan ; chemistry ; Drugs, Chinese Herbal ; chemistry ; Microscopy, Electron, Scanning ; Panax ; chemistry ; Polyethylene Glycols ; chemistry ; Temperature

In this study, polyacrylicacid precipitation alkalescence protein from Momordica charantia L. seeds was studied, and the effect of conditions on experiment was also evaluated. Isoelectric precipitation is achieved by adjusting the pH of a protein solution and is based on that a protein's solubility is at minimum at its pI. The sample was titrated to pH 6.0 with citric acid, and 14.62% proteins were precipitated. With hydrochloric acid to pH 4.0, 32.49% proteins were precipitated. With the acetic acid to pH 6.0 and pH 4.0, 26.17% and 38.72% proteins were precipitated, respectively. In the 1 mL Bitter melon seeds extraction(pH 4.0) adjusted by acetic acid, hydrochloric acid and citric acid, the optimum dosage of PAA (1%) precipiting alkalescency protein (pl 8.65-9.30) was 100 microL, 120 microL and 100 microL, respectively. The respective extraction (1mL) was titrated to pH 5.0, pH 4.0, and pH 3.0 by acetic acid. After isoelectric precipitation, the PAA precipitation protein was performed. When concentration of PAA (1%) was 160 microL/mL, the protein decreased in the supernatant was 33.77% at pH 5.0, and 43.56% at pH 3.0. When concentration of PAA (1%) was 120 microL/mL, the protein decreased in the supernatant was 30.83% at pH 4.0. PAA-Protein complex could redissolve in alkaline conditions (pH > 9.0) and the protein most easilly redissolved when the NaCL was 3.0%. The bitter melon seeds extraction after PAA purification flowed through the Sephadex G-75 columns. The peaks I and II were obtained after 175 min and 300 min, respectively. SDS-PAGE and IEF analysis showed that the molecule weight from peaks I was 30 kD with pI 9.5, peaks II 10 kD with pI 9.3.
Acrylic Resins ; chemistry ; Chemical Precipitation ; Momordica charantia ; chemistry ; Plant Extracts ; chemistry ; Plant Proteins ; chemistry ; isolation & purification ; Seeds ; chemistry

We have developed two novel cell co-culture system, without any on cell type combination limitation, utilizing a polymer surface which is temperature-sensitive with respect to its cell adhesion characteristics. One system involves a patterned co-culture of primary hepatocytes with endothelial cells utilizing patterned masked of the electron-beam cured, temperature-responsive polymer, poly (N-isopropylacrylamide) (PIPAAm) by masked electron beam irradiation. Hepatocytes were cultured to confluency at 37 degrees C on these surfaces. When the culture temperature was reduced below 32 degrees C, cells detached from the PIPAAm-grafted areas without any need for trypsin. Endothelial cells were then seeded onto the same surfaces at 37 degrees C. These subsequently seeded endothelial cells adhered only to the now-exposed PIPAAm-grafted domains and could be co-cultured with the hepatocytes initially seeded at 37 degrees C in well-ordered patterns. The other system involves a double layered co-culture obtained by overlaying endothelial cell sheets of the designed shape onto hepatocyte monolayers. The endothelial cells adhered and proliferated on the PIPAAm-grafted surface, as on polystyrene tissue culture dishes at 37 degrees C. By reducing the temperature, confluent monolayers of cells detached from the PIPAAm surfaces without trypsin. Because the recovered cells maintaed intact cell-cell junctions together with deposited extracellular matrix, the harvested endothelial cell sheets, with designed shapes, were transferable and readily adhered to hepatocyte monolayers. Stable double layered cell sheets could be co-cultivated. These two co-culture methods enabled long-term co-culture of primary hepatocytes with endothelial cells. Hepatocytes so co-cultured with endothelial cells maintained their differentiated functions, such as albumin synthesis for unexpectedly long periods. These novel two co-culture systems offer promising techniques for basic biologic researches upon intercellular communications, and for the clinical applications of tissue engineered constructs.
Acrylic Resins/chemistry* ; Animal ; Coculture ; Cytological Techniques* ; Endothelium/cytology* ; Human ; Surface Properties ; Temperature*