Addition Of TMP Research Articles

Rheological behaviors and foaming behaviors of crosslinked ethylene–vinyl acetate with polyfunctional monomers

AbstractTo produce ethylene–vinyl acetate (EVA) foams with a higher foaming ratio and stable cell size, the efficiency of the crosslinking reaction is required to conduct simultaneously with the blowing reaction. Hence, the multifunctional monomer trimethylolpropane trimethacrylate (TMP) as a crosslinking promoter and a crosslinking agent dicumyl peroxide are used together as a crosslinking system to EVA foaming, when chemical blowing agent azodicarbonamide (ADC) is used. The TMP concentration of approximately 1.0 phr (per hundred resin) is most effective for balancing the expansion ratio and fine cell size. In the SEM diagram and expansion ratio results, it can be found that when the concentration of TMP ranges from 0 to 1.0 phr, the cell mean size is reduced from 360.3 to 140.5 μm and the expansion ratio is reduced from 13.6 to 9.1 at 170°C. The results of time‐sweep experiment of thermogravimetric analysis (TGA) show that the foaming time of ADC in the melt increases with the addition of TMP. Capillary rheometer and rotational rheometer tests show that the viscosity and the crosslinking efficiency of the melt are improved with the TMP addition. The curing time has been reduced from 2.93 to 2.22 min for 170°C.

Synthesis and characterization of soft polyurethane for pressure ulcer prevention

A series of super-soft polyurethanes was prepared by synthesizing lightly crosslinked polyurethane with low isocyanate:hydroxyl ([NCO]:[OH]) molar ratios. The starting materials were polymeric isocyanate (pMDI), polypropylene glycol (PPG), and 1,1,1-tris(hydroxymethyl)propane (TMP). The effects of the [NCO]:[OH] molar ratio and concentrations of the crosslinking agent TMP on the crosslink density and the thermal, dynamic-mechanical, and mechanical properties of the polyurethanes were determined. In addition, TMP generates chemical and physical crosslinks within polyurethane; therefore, data calculated using the Flory-Rehner equation and the rubber elasticity were compared. The success of the reaction between pMDI and PPG was confirmed using Fourier-transform infrared spectroscopy. The synthesized polyurethanes exhibited a mixing phase between soft and hard segments. The addition of TMP increased the crosslinking density, resulting in increased glass transition temperature, tensile properties, and hardness; however, the pressure distribution was suppressed. The synthesized polyurethane showed effective properties for pressure ulcer relief applications.

Dentinal tubule obliteration using toothpastes containing sodium trimetaphosphate microparticles or nanoparticles.

This in vitro study evaluated the effect of microparticles (TMPmicro) or nanoparticles (TMPnano) TMP associated with fluoride (F) in toothpaste formulations on the obliteration of dentinal tubules (DT). The dentinal tubules of bovine dentin blocks were unobstructed by immersion in 37% phosphoric acid solution. Blocks (n = 20/group) underwent mechanical brushing (2×/day) during 7days with toothpastes: placebo, 1100ppm F, and 1100 with 3% TMPmicro or 3% TMPnano. After that, ten blocks of each group were immersed in citric acid (pH 3.2) for 1min. The number, diameter and area of unobstructed DT, atomic % of chemical elements from precipitates, and the mineral concentration were quantified. Data were submitted to two-way ANOVA, followed by Student-Newman-Keuls test (P < 0.05). Toothpastes containing TMPmicro and TMPnano promoted greater obliteration of DT and greater mineral concentration compared to other groups (P < 0.05). Placebo and 1100ppm F group presented similar obliteration but 1100ppm F group promoted higher mineral concentration. Higher Ca/P ratios were observed in groups treated with TMP; the acid challenge reduced Ca/P ratio for all groups. The atomic % of C and N was significantly lower for TMP toothpastes before acid challenge, but increased afterwards. It was concluded that the addition of TMPmicro or TMPnano to F toothpastes produced greater obliteration of dentinal tubules and higher mineral concentration when compared with 1100ppm F. By the addition of TMP, fluoride toothpastes may occlude the dentinal tubules, with potential to reduce dentin hypersensitivity.

An Ion-Pair HPLC Method for Simultaneous Determination of Exogenous Phosphocreatine and Its Metabolite Creatine and Related ATP in Rabbit Plasma and RBC: Application to a Pharmacokinetic Study

A specific, precise and accurate ion-pair HPLC-UV method has been developed and validated for simultaneous determination of phosphocreatine (PCr), and its metabolite creatine (Cr) as well as related ATP in plasma and red blood cell (RBC) of rabbits. After addition of TMP as IS, the samples were deproteinized with 6% PCA. The analytes were separated on a Kromasil C18 column using a tertiary gradient mobile phase composed of buffer A (0.2% KH2PO4 + 0.08% tetrabutyl ammonium hydrogen sulphate, pH 3.0), buffer B (buffer A adjusted to pH 7.5 with 1 mol/L NaOH) and MeOH. Detection wavelengths were set at 210 nm for PCr and Cr and 260 nm for ATP and TMP. Some blank samples were initially run for baseline subtraction. The linear detection responses were obtained for PCr concentration over a range of 10 - 7500 mg/ml (plasma) and 5 - 2500 mg/ml (RBC) and for both Cr and ATP concentrations of 10 - 1500 mg/ml (plasma) and 5 - 750 mg/ml (RBC) (r > 0.99). The QC samples of 3 analytes showed intra-day and inter-day precisions (RSD) of - 107%. The method was successfully used to simultaneously determine plasma and RBC concentrations of the 3 analytes and to study pharmacokinetics after iv administration of PCr to rabbits.

Effects of turmeric (Curcuma longa) on the expression of hepatic genes associated with biotransformation, antioxidant, and immune systems in broiler chicks fed aflatoxin

The objective of the present study was to evaluate the efficacy of curcumin, an antioxidant found in turmeric (Curcuma longa) powder (TMP), to ameliorate changes in gene expression in the livers of broiler chicks fed aflatoxin B(1) (AFB(1)). Four pen replicates of 5 chicks each were assigned to each of 4 dietary treatments, which included the following: A) basal diet containing no AFB(1) or TMP (control), B) basal diet supplemented with TMP (0.5%) that supplied 74 mg/kg of curcumin, C) basal diet supplemented with 1.0 mg of AFB(1)/kg of diet, and D) basal diet supplemented with TMP that supplied 74 mg/kg of curcumin and 1.0 mg of AFB(1)/kg of diet. Aflatoxin reduced (P < 0.05) feed intake and BW gain and increased (P < 0.05) relative liver weight. Addition of TMP to the AFB(1) diet ameliorated (P < 0.05) the negative effects of AFB(1) on growth performance and liver weight. At the end of the 3-wk treatment period, livers were collected (6 per treatment) to evaluate changes in the expression of genes involved in antioxidant function [catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), glutathione S-transferase (GST)], biotransformation [epoxide hydrolase (EH), cytochrome P450 1A1 and 2H1 (CYP1A1 and CYP2H1)], and the immune system [interleukins 6 and 2 (IL-6 and IL-2)]. Changes in gene expression were determined using the quantitative real-time PCR technique. There was no statistical difference in gene expression among the 4 treatment groups for CAT and IL-2 genes. Decreased expression of SOD, GST, and EH genes due to AFB(1) was alleviated by inclusion of TMP in the diet. Increased expression of IL-6, CYP1A1 and CYP2H1 genes due to AFB(1) was also alleviated by TMP. The current study demonstrates partial protective effects of TMP on changes in expression of antioxidant, biotransformation, and immune system genes in livers of chicks fed AFB(1). Practical application of the research is supplementation of TMP in diets to prevent or reduce the effects of aflatoxin in chicks fed aflatoxin-contaminated diets.

Efficacy of Turmeric (Curcuma longa), Containing a Known Level of Curcumin, and a Hydrated Sodium Calcium Aluminosilicate to Ameliorate the Adverse Effects of Aflatoxin in Broiler Chicks

A 3-wk feeding study was conducted to evaluate the efficacy of turmeric (Curcuma longa) powder (TMP), containing a known level of curcumin, and a hydrated sodium calcium aluminosilicate (HSCAS; Improved Milbond–TX, IMTX, an adsorbent, Milwhite Inc., Houston, TX) to ameliorate the adverse effects of aflatoxin B1 (AFB1) in broiler chicks. Four pen replicates of 5 chicks each were assigned to each of 7 dietary treatments, which included the basal diet not containing TMP, HSCAS, or AFB1 (control); basal diet supplemented with 0.5% food grade TMP that contained 1.48% total curcuminoids (74 mg/kg); basal diet supplemented with 0.5% HSCAS; basal diet supplemented with 1.0 mg/kg AFB1; basal diet supplemented with 0.5% TMP and 1.0 mg/kg AFB1; basal diet supplemented with 0.5% HSCAS and 1.0 mg/kgAFB1; and basal diet supplemented with 0.5% TMP, 0.5% HSCAS, and 1.0 mg/kg AFB1. The addition of TMP to the AFB1 diet significantly (P < 0.05) improved the weight gain of chicks, and the addition of HSCAS to the AFB1 diet significantly (P < 0.05) improved feed intake and weight gain, and reduced relative liver weight. The addition of TMP or HSCAS and TMP with HSCAS ameliorated the adverse effects of AFB1 on some of the serum chemistry parameters (total protein, albumin, cholesterol, calcium). Further, decreased antioxidant functions in terms of level of peroxides, superoxide dismutase activity, and total antioxidant concentration in liver homogenate due to AFB1 were also alleviated by the inclusion of TMP, HSCAS, or both. The reduction in the severity of hepatic microscopic lesions due to supplementation of the AFB1 diet with TMP and HSCAS demonstrated the protective action of the antioxidant and adsorbent used in the present study.

Inhibition of atmospheric lean and rich CH 4/O 2/Ar flames by phosphorus-containing compound

The mechanism of flame inhibition by phosphorus-containing species (PCSs) is known to involve their effect on the recombination of atoms and free radicals in flames. Chemical inhibition of laminar atmospheric methane/oxygen flames by trimethylphosphate over a range of equivalence ratio has been studied experimentally, using the heat flux method for measurement of burning velocity and molecular beam mass spectrometry for measurement of concentration profiles of both stable and labile species, and with numerical modeling using detailed chemical kinetic reaction mechanisms. Concentrations of H and OH in flames with and without the inhibitor were obtained by measurements and modeling. The addition of the inhibitor reduces the maximum concentrations of H and OH (in the reaction zone) in the lean and rich flame. This reduction is much larger in the rich flame than in the lean one. The concentration profiles of PCSs—PO, PO 2, HOPO, HOPO 2, and H 3PO 4 were measured and simulated for rich and lean flames stabilized on a flat burner. According to flame speed measurements for inhibited CH 4/air flames over a range of ϕ, the inhibition effectiveness E i increases in the range of ϕ = 0.8–1.2 and then decreases with a further increase of ϕ. The increase in E i in the range ϕ = 0.7–1.2 is attributed to a change of PCSs composition. The reduction in E i for ϕ > 1.2 can be explained by a decrease in the concentration of active PCSs due to an increase in the concentration of inactive species, such as CH 3PO 2 and other products of incomplete combustion of TMP. The inhibition effectiveness E i versus ϕ correlates with change of H and OH concentration at addition of TMP in flame. Validation of the previously developed model for inhibition by PCSs has shown that in spite of some discrepancies it adequately describes many experimental results.

Effect of tetramethylpyrazine on exocrine pancreatic and bile secretion.

To investigate the effect of tetramethylpyrazine (ligustrazine, TMP) on the secretion of exocrine pancreas (and biliary). In in vivo study, we investigated the effect of TMP on the secretion of pancreatic-bile juice (PBJ) in rats. Using human pancreatic duct cell line, CAPAN-1, combined with the short-circuit current (ISC) technique we further studied the effect of TMP on the pancreatic anion secretion. Administration of TMP (80 mg/kg, i.p.) significantly increased the secretion of PBJ (P<0.05), but the pH of PBJ and the secretion of pancreatic protein were not significantly affected. Basolateral addition of TMP produced a dose-dependent increase in ISC (EC50=1.56 mmol/L), which contained a fast transient ISC response followed by a slow decay. Apical application of Cl- channel blockers, DPC (1 mmol/L), decreased the response by about 67.1% (P<0.001), whereas amiloride (100 micromol/L), a epithelial sodium channel blockers, had no effect. Removal of extracellular HCO3- abolished TMP-induced increase in ISC by about 74.4% (P<0.001), but the removal of external Cl- did not. Pretreatment with phosphodiesterase inhibitor, IBMX(0.5 mmol/L), decreased the TMP-induced ISC by 91% (P<0.001). TMP could stimulate the secretion of PBJ, especially pancreatic ductal HCO3- secretion via cAMP or cGMP-dependent pathway. It need further study to investigate the roles of cAMP or cGMP in the effect of TMP on the secretion of exocrine pancreas.

Tetramethylpyrazine Protects Mice against Thioacetamide-Induced Acute Hepatotoxicity

In this study, the intraperitoneal administration of 1 mg/kg thioacetamide (TAA) produced hepatotoxicity in mice. The increase in serum SGOT and SGPT produced at 24 h by this regimen was decreased in a dose-dependent manner by coadministration of tetramethylpyrazine (TMP; 10, 25 and 50 mg/kg). A rise in serum interleukin-2 was similarly prevented. Increased concentrations of malondialdehyde (MDA) generated in vitro in liver homogenates prepared from TAA-treated mice were decreased by TMP treatments. The increase in MDA produced by TAA was also prevented by in vitro addition of TMP to liver homogenates. These results suggest that part of the hepatocellular injury induced by TAA is mediated by oxidative stress caused by the action of cytokines through lipid peroxidation. TMP appears to act by preventing lipid peroxidation.

Tetramethylpyrazine protects mice against thioacetamide-induced acute hepatotoxicity.

In this study, the intraperitoneal administration of 1 mg/kg thioacetamide (TAA) produced hepatotoxicity in mice. The increase in serum SGOT and SGPT produced at 24 h by this regimen was decreased in a dose-dependent manner by coadministration of tetramethylpyrazine (TMP; 10, 25 and 50 mg/kg). A rise in serum interleukin-2 was similarly prevented. Increased concentrations of malondialdehyde (MDA) generated in vitro in liver homogenates prepared from TAA-treated mice were decreased by TMP treatments. The increase in MDA produced by TAA was also prevented by in vitro addition of TMP to liver homogenates. These results suggest that part of the hepatocellular injury induced by TAA is mediated by oxidative stress caused by the action of cytokines through lipid peroxidation. TMP appears to act by preventing lipid peroxidation.

Thermal and mechanical properties of diglycidylether of bisphenol A/ trimethylolpropane triglycidylether epoxy blends cured with benzylpyrazinium salts

AbstractThe effect of blend composition on thermal stability and mechanical properties of diglycidylether of bisphenol A (DGEBA)/trimethylolpropane triglycidylether (TMP) epoxy blends cured with benzylpyrazinium salts (N‐benzylpyrazinium hexafluoroantimonate, BPH) as a thermal latent catalyst was investigated. The thermal stability, characterized by the initial decomposition temperature, temperature of maximum rate of weight loss, integral procedural decomposition temperature, and activation energy for decomposition, increase in DGEBA‐rich compositions. This could be due to the long repeat unit and stable aromatic ring in the DGEBA. The mechanical properties are also discussed in terms of the fracture toughness (KIC), flexural and impact tests for the blend composition studied. The addition of TMP into DGEBA gives systematic improvements in fracture toughness, which results from the increase in aliphatic and flexible chain segments of TMP.© 2002 Society of Chemical Industry

Etching Characteristics of Silica-Based Optical Waveguide for Planar Lightwave Circuit

We have successfully synthesized high quality silica by using plasma enhanced chemical vapor deposition (PECVD) of tetraethyl orthosilicate (TEOS) precursors. Optical transmission spectroscopy and Fourier transform infrared (FTIR) spectroscopy indicated that, the TEOS/O 2 ratio had pronounced influence on the deposition rate and optical properties for SiO 2 films. Modification on refractive index (n) for the synthesis of single mode optical waveguide can be easily achieved in PECVD process, by addition of TMP in the precursors. Based on this, a Si/SiO 2 /P-SiO 2 /SiO 2 ridge-type waveguide structure could be derived following a photolithography, lift-off and reactive ion etching (RIE) process sequence. In this study, silica etch characteristics of different etching parameters were investigated using CHF 3 /O 2 as the etch gases. Metal mask could offer higher selectivity and yielded smaller deposition of polymer, so that an optical quality ridge structure with high vertical sidewall angle and dimension controllability, and smooth sidewall surface became possible. The results came out that the etching parameters such as RF power and CHF 3 /O 2 ratio had significant influence on the etch rates, etch selectivities and etch profiles. Under optimal etching conditions and post-treatment, a single mode waveguide with vertical etch profile and smooth sidewall could be fabricated successfully.

Etching Characteristics of Silica-Based Optical Waveguide for Planar Lightwave Circuit

We have successfully synthesized high quality silica by using plasma enhanced chemical vapor deposition (PECVD) of tetraethyl orthosilicate (TEOS) precursors. Optical transmission spectroscopy and Fourier transform infrared (FTIR) spectroscopy indicated that, the TEOS/O 2 ratio had pronounced influence on the deposition rate and optical properties for SiO 2 films. Modification on refractive index (n) for the synthesis of single mode optical waveguide can be easily achieved in PECVD process, by addition of TMP in the precursors. Based on this, a Si/SiO 2 /P-SiO 2 /SiO 2 ridge-type waveguide structure could be derived following a photolithography, lift-off and reactive ion etching (RIE) process sequence. In this study, silica etch characteristics of different etching parameters were investigated using CHF 3 /O 2 as the etch gases. Metal mask could offer higher selectivity and yielded smaller deposition of polymer, so that an optical quality ridge structure with high vertical sidewall angle and dimension controllability, and smooth sidewall surface became possible. The results came out that the etching parameters such as RF power and CHF 3 /O 2 ratio had significant influence on the etch rates, etch selectivities and etch profiles. Under optimal etching conditions and post-treatment, a single mode waveguide with vertical etch profile and smooth sidewall could be fabricated successfully.

Invariant amino acid replacement affects the dihydrofolate reductase function and its gene expression

Three different forms of dihydrofolate reductase (DHFR) from Escherichia coli with amino acid replacements Thr35----Asp, Asn37----Ser and Arg57----His, and one form containing all three of these changes were obtained by oligonucleotide-directed mutagenesis. These amino acids are on the surface of the protein and two of them (Thr35 and Arg57) are invariant for known sequences of DHFR. Conversion of Asn37----Ser has no effect on the functional activity or the protein level in the cells. The Thr35----Asp replacement leads to a sharp decrease in the protein level, while the addition of a DHFR inhibitor, trimethoprim (Tmp), to the growth medium increases the level of DHFR in the cells. There is a very small quantity of DHFR with all three amino acid changes. The addition of Tmp to the growth medium also leads to an increase in the mutant protein levels. The mutant with the Arg57----His replacement renders the cells sensitive to Tmp, but the level of DHFR is the same as for the wild-type protein. It is suggested that the invariant Thr35 is important for the stable conformation of DHFR whereas Arg57 is essential for protein activity. Various structural and functional aspects of these results are discussed.

Reduction of rat caries by trimetaphosphate on different tooth surfaces: Variations produced by diet and oral flora

Osborne-Mendel rats fed coarse particle Diet 585 developed mostly sulcal lesions and showed no increase in caries as a result of being inoculated with exogenous mixed cariogenic flora including a strain of Streptococcus mutans. Uninoculated rats fed high sucrose Diet 2000 developed mostly sulcal lesions, while the inoculated animals showed some increase in the sulci and a very pronounced increase on the smooth surfaces. The addition of TMP to both of the diets was associated with a limited, but significant, reduction in sulcal caries and almost complete elimination of smooth surface lesions, which were already low on Diet 585 and a highly significant reduction on Diet 2000.

Electron spin resonance study of trimethylolpropane monoallyl ether in radical polymerization

AbstractTrimethylolpropane monoallyl ether (TMP) was studied with an x‐band electron spin resonance (ESR) spectrometer by applying a flow method, developed by Dixon and Norman, in which TMP was subjected to hydroxyl radical attack. The observed ESR spectra were assigned to two radicals formed by addition of hydroxyl radical to TMP and one by abstraction of hydrogen from the allylic group of TMP. The ESR spectra from copolymerizing systems of vinyl acetate (VAc) and methyl acrylate (MA) with TMP were also studied. In the system VAc‐TMP, the ESR spectrum showed in addition to VAc radicals the presence of the three TMP radicals. In the system MA‐TMP, the ESR spectrum was mainly due to TMP radicals in which the allylic radicals were dominant. This result is consistent with the observation that polymerization of MA is strongly retarded by the addition of TMP, which is interpreted as due to the high reactivity of MA radicals to TMP monomer.