Solution Of AP Research Articles

Thermal processes improving antibrowning potential of mixed Aloe vera and pineapple core extract solution on browning inhibition of fresh‐cut apples

SummaryAloe vera and pineapple fruit extract have been applied as natural antibrowning agent for fresh‐cut products. The effect of different thermal treatment processes (high‐temperature–short‐time pasteurisation at 80 ± 1 °C for 15 s and sterilisation at 121 ± 1 °C for 20 min) of mixed A. vera and pineapple core extract solution at a ratio of 1:1 (v/v) (AP) on enzymatic browning control of fresh‐cut ‘Gala’ apples was investigated. Both thermal processes increased the antioxidant activities of AP solution compared to unheated AP solution. Coating of both thermal processed AP solutions alleviated the increased browning incidence of the fresh‐cut apples during storage. Compared to sterilised AP coating, the pasteurised AP coating maintained visual appearance, whiteness index (WI) and L* values as well as inhibited browning incidence due to the prevention of increased a*, b*, ΔE* and browning index (BI) values of fresh‐cut apples during storage. The fresh‐cut apples coated with pasteurised AP had lower total phenolic compounds and polyphenol oxidase activity compared to the samples coated with sterilised AP. These suggested that the suitable thermal process was helpful to enhance antibrowning ability of AP coating agents to control enzymatic browning reaction of fresh‐cut fruits.

Preparation of Fine Ammonium Perchlorate by Employing Dual‐Sonic Premixer: Freeze‐Drying Method

AbstractAmmonium perchlorate (AP)‐based composite propellant is the most widely used solid propellant. Fine AP is required to obtain a propellant with a high burning rate. To prepare fine AP, an emulsion was prepared by emulsifying toluene and the AP solution. The emulsion was frozen rapidly with liquid nitrogen and then freeze‐dried. Fine AP was prepared by this freeze‐drying method. In this study, the emulsion was prepared with the premixer adopted dual‐sonic technology and an attempt was made to prepare finer AP. By using a dual‐sonic premixer, the emulsion was efficiently prepared, and therefore, a fine AP sample was obtained, compared with the homogenizer that is commonly used. It was found that the AP sample could be used as a propellant oxidizer according to its impact and thermal sensitivities.

AMT/APS Multilayered Films as Adherence Promoters for Epoxy Coatings on Carbon Steel—Part I: Influence of Curing Conditions on Anticorrosive Properties of AMT/APS Films in Saline Medium

The first part of this work evaluates the influence of the cure conditions on the preparation of 3-aminopropyl trimethoxysilane (APS) and the corrosion inhibitor 5-amino-1,3,4-thiadiazole-2-thiol (AMT) multilayered films onto AISI 1020 carbon steel. The steel samples were pretreated in a 10−2 mol L−1 AMT solution for 3 h, immersed twice in a 5% v/v APS solution, and heat-treated at different temperatures and curing times. Regardless of the curing conditions used, electrochemical impedance spectroscopy (EIS) in 0.5 mol L−1 NaCl showed that the inhibitor pretreatment favored the formation of a more protective film when compared to the alkaline-treated steel, covered or not by AMT or APS thin films. The AMT/APS multilayered film cured at 100 °C and 80 min exhibited the best improvement in the anticorrosive properties among all of the films studied in this work, which was confirmed by potentiodynamic polarization (PP) experiments performed in the same electrolyte. XPS analysis of the selected AMT/APS film system revealed the formation of a Fe-O-S-R chemical bond, confirming the interaction of the AMT inhibitor with the NaOH-treated steel surface. The present findings indicate that the APS-AMT interaction may have occurred from the N-S bond, identified in the N 1s spectrum.

Surface modification of Momordica angustisepala fiber using temperature-activated amino-functionalized alkali-silane treatment

Momordica angustisepala fiber (MAf) is like other natural fibers that usually have weak interfacial bonding when used in the production of polymer composites. Natural fibers are usually treated to improve their properties. This present work investigates surface modification of Momordica angustisepala fiber using temperature-activated amino-functionalized alkali-silane treatment. The fibers were soaked in an 80 ml sodium hydroxide (OH) solution before silane functionalization in 2 ml of aminopropyltriethoxysilane in 100 ml ethanol (OH-APS). The temperature of the APS solution was 75 and 150 °C with soaking time of 3 and 6 h. Optimized properties were obtained at a treatment temperature of 150 °C and a time of 3 h. It was established that the combined effect of activated temperature and OH-APS chemical treatment of MAf is promising and can be used to improve the interfacial bonding during polymer composite production.

Tailings Storage Facilities (TSFs) Dust Control Using Biocompatible Polymers

Mine tailings storage facilities (TSFs) can be a significant source of fine, respirable dust. This dust poses concerns, especially for nearby communities, because of its detrimental impact on respiratory health. To address these concerns, this study examined the effectiveness of commercially available polymers, known for their biocompatible and environmentally friendly features, to prevent dust generation from upstream-type TSFs in active mining operations. It focused on two areas in TSFs: the tailings beach and slope/dike surfaces. Two types of polymers—polyethylene glycol and poloxamer—were selected, and their effectiveness was evaluated in a series of phased laboratory and field tests. The lab tests investigated the moisture-retention capacity of the tailings after treatment with the polymer solutions as well as the ability of these solutions to reduce dust emissions. Polymers were applied to a tailings bed surface in the lab and dust was generated from this surface using a wind tunnel. PM10 and PM2.5 concentrations were measured using laser-diffraction dust sensors, and the polymers were found to have reduced dust emissions up to 95%. Small-scale wind-blowing tests were conducted in the field (specifically, in a controlled environment at a TSF) to evaluate polymer effectiveness on the tailings beach and slope/dike areas. The tests revealed that the AP could efficiently suppress approximately 80% of PM10 and PM2.5 dust emissions at both types of areas. Finally, 1000 gallons of AP solution were discharged at the top of tailings beach and slope/dike areas, respectively, and found to be effective. The results of these tests showed the high potential of the biocompatible polymers to be a feasible solution for reducing the respirable dust emissions from upstream TSFs in arid and semi-arid regions.

Price Determinism in Specialized Producing Economy

In an economy with n kinds of products, producers are specialized to produce one kind of product and exchange for the others. Exchange matrix A consists of supplies and demands. Price vector p is the solution of Ap = 0.When R(A) = n – 1, the price is determined given total money amount. When R(A) = n – m, the economy can be divided into m sub-economies with no exchange of products between any two of them. In each sub-economy the price is determined.

Formation and properties of selected quantum dots in maize amylopectin matrix

CdS, ZnS, Ga2S3, CaS and Cs2S quantum dots (QDs) were generated in the amylopectin (Ap) matrix. They all emitted a light between 460 (ZnS) and 475 (CdS) nm. Sizes of Ga2S3 and CdS QDs were 7–9nm and 5–7nm, respectively. Single ZnS QDs had 6–7nm but they readily aggregated. The CaS and Cs2S appeared mainly as 30–100nm aggregates. There were no significant interactions between QDs and the Ap matrix. Presented method appeared unsuitable for the generation of CaS and Cs2S QDs as they as well as their substrates [Ca(NO3)2] hydrolyzed. Calcium compounds formed complexes with Ap and alkaline solution from CsOH could produce cesium salts of Ap as well as cause oxidation of Ap.

Maximizing the number of oxygen-containing functional groups on activated carbon by using ammonium persulfate and improving the temperature-programmed desorption characterization of carbon surface chemistry

The number of oxygen-containing functional groups (OCFGs) on the surface of a commercial activated carbon (AC) was maximized using ammonium persulfate ((NH 4) 2S 2O 8, APS) as an oxidant. Effects of the oxidation conditions, including temperature, time and concentration of APS, on physical and chemical properties of the treated AC were examined to develop a relationship between the oxidation conditions and surface chemistry of AC. A maximum amount of oxygen, 18.7 mmol/g, on the AC was achieved by oxidation with 2.0 mol/L APS solution and an APS/AC weight ratio of 9.1 at 60 °C for 3 h. Temperature-programmed desorption coupled with mass spectrometry (TPD–MS) was used to identify and quantify OCFGs on the AC samples. It was found that using the TPD–MS method currently reported in the literature to quantify various OCFGs on the carbon surface on the basis of TPD–CO 2 and TPD–CO profiles may significantly underestimate the number of carboxyl groups, and overestimate anhydrides and lactones due to some in situ reactions of OCFGs during the TPD–MS analysis. The amount of H 2O and CO released in the temperature range corresponding to decomposition of carboxyl groups should be taken into account when estimating the amount of carboxyl groups on AC.

Characterization of the agglomeration of roasted shredded cassava (Manihot esculenta crantz) roots

AbstractRoasted and granulated cassava roots flour, known as ‘rale’ in the south of Mozambique, is a common meal in sub‐Saharan Africa and is consumed reconstituted with hot or cold water. In this work, analysis of rale was carried out with the aim of understanding what determines the agglomeration properties. Rale is agglomerated roasted cassava flour with about 95% of starch gelatinized. The pre‐gelatinized and agglomerated cassava gives cold swelling as well as a resistance against disintegration when heated. The softness of swollen agglomerated granules is temperature dependent. Microscopy of rale agglomerates shows that the granulation is formed by partial swelled starch granules bound together by retrograded leached AM. A physical model of rale consisting of glass beads agglomerated by drying with an AP or AM solution showed that particles with retrograded AM were resistant to disintegration in water at 90°C while glass beads agglomerated with AP did not show comparable heat resistance. Thus it was concluded that the leaching and retrogradation of AM is essential to obtain the rale agglomeration and functionality.

Understanding the relationship between the structure of an organofunctional methoxysilane bilayer and its properties as adhesion primer for Zn-epoxidized rubber system

The structure of a new organofunctional methoxysilane bilayer system, which was found to improve the adhesion of epoxidized natural rubber (ENR) to zinc, is analyzed by High Resolution Electron Energy Loss and Infrared Reflection Absorption Spectroscopy. This bilayer is formed when zinc plate is successively dip-coated in water–alcohol solutions of γ-mercaptopropyltrimethoxysilane and aminopropyltrimethoxysilane. The optimal adhesion, obtained when both silane layers are cured at 110 °C, is due to the specific structure of this bilayer, which depends dramatically on the cure temperature of the first layer. From HREELS results under the conditions of an impact mechanism, it is shown that the surface density of NH 2 groups (which react with the epoxy groups of rubber and provide the adhesion of the whole system) is much higher when the γ-MPS layer is cured at 110 °C instead of 70 °C or room temperature. This high NH 2 group surface density is also confirmed by wettability measurements, which indicate a marked increase in the basic component of the surface energy at 110 °C. An IRRAS study of the γ-MPS layer deposited on zinc shows that up to 70 °C hydrolysis of the SiOCH 3 groups is poor, and becomes effective only after the zinc/γ-MPS layer is dipped in the basic APS solution. This makes the penetration of APS molecules across the γ-MPS layer easier and, consequently, amino groups can interact with zinc. Therefore, they are unavailable for a reaction with epoxy groups. In contrast, when the γ-MPS layer is cured at 110 °C or higher, hydrolysis of its SiOCH 3 groups begins and, simultaneously, lateral cross-linking occurs between SiOH groups. Under these conditions, penetration of the γ-MPS layer by APS molecules is hindered and lateral mixed cross-linking occurs at the interface γ-MPS/APS via the SiOH groups. This entails a greater density of pendant amino groups directed towards the surface, which enhances the practical adhesion of rubber to zinc.

Osteoinduction using by Human BMP-2-physio-functional Bioactive Ceramics

Pur p ose: T o assess the properties and the osteogenic potency of the calcium phosphate-recom - binant human morphogenetic protein-2 (C aP- rhBMP- 2 composite) on glass-ceramics. Mat e r ia ls and Met h ods: Bioactive glass-ceramics,as a scaffold, and a calcium phosphate (C aP) solution (pH 7.4) were prepared. R ecombinant human bone morphogenetic protein-2 (rhBMP- 2) was purified from C HO- K1 cells by transfecting the cells with BMP- 2 cD NA. T he glass-ceramics were soaked for 3 days at room temperature in saline, a CaP only solution, and a CaP solution containing rhBMP- 2. S canning electron microscopy (S EM) , Fourier transform infrared reflection spectroscopy (F T-IR ), thin film X -ray diffraction (T F-X RD) and immunofluorescent staining (IF) of the anti-human BM P -2 to composite-coated scaffold were performed to verify the characterization of the scaffold surface. In addition, R T-P CR of osteogenic marker gene and S EM photography were performed after adhering the mouse preosteoblast M C3T3- E 1 cells in order to assess the osteoinductivity. Resul ts : CaP-rhBMP-2 composite was coated on the surface of glass-ceramics, as confirmed by S EM, FT-IR , TF-X RD spectrum, and IF . The C aP- rhBMP- 2 composite on the glass-ceramic showed a globular shape covered with fine spikes while the C aP on the glass-ceramic showed a fine spike structure on the flat glass surface. The expression of collagen type I and alkaline phosphatase mRNAs had increased 4 hours after cell seeding. In addition, the level of osteocalcin mRNA ex- pression had increased significantly by 3 days in the CaP-rhBMP-2 composite compared with the control and C aP group. The S EM photographs showed more active filopodia formation in the C aP- rhBMP- 2 composite than the other groups. T here was extensive newly synthesized extracellular matrix around the osteoblasts and C aP- rhBMP- 2 composite nodule.

Solutions of the congruence 𝑎^{𝑝-1}≡1 (mod 𝑝^{𝑟})

To supplement existing data, solutions of a p − 1 ≡ 1 ( mod p 2 ) a^{p-1} \equiv 1 \pmod {p^2} are tabulated for primes a , p a, p with 100 > a > 1000 100 > a > 1000 and 10 4 > p > 10 11 10^4 > p > 10^{11} . For a > 100 a > 100 , five new solutions p > 2 32 p > 2^{32} are presented. One of these, p = 188748146801 p = 188748146801 for a = 5 a = 5 , also satisfies the “reverse” congruence p a − 1 ≡ 1 ( mod a 2 ) p^{a-1} \equiv 1 \pmod {a^2} . An effective procedure for searching for such “double solutions” is described and applied to the range a > 10 6 a > 10^6 , p > max ( 10 11 , a 2 ) p >\max \, (10^{11}, a^2) . Previous to this, congruences a p − 1 ≡ 1 ( mod p r ) a^{p-1} \equiv 1 \pmod {p^r} are generally considered for any r ≥ 2 r \ge 2 and fixed prime p p to see where the smallest prime solution a a occurs.

Pharmaceutical Development of a Parenteral Lyophilized Formulation of the Investigational Polymer-Conjugated Platinum Anticancer Agent AP 5280

AP 5280 is a novel polymer-conjugated platinum anticancer agent showing promising in vitro and in vivo activity against solid tumors. The aim of this study was to develop a parenteral pharmaceutical dosage form for phase I clinical trials. AP 5280 drug substance was characterized by using a wide range of analytical techniques and showed excellent solubility in water. However, as aqueous solutions of AP 5280 proved to be labile upon sterilization by moist heat, it was decided to develop a lyophilized dosage form. Initially, glass vials were used as primary packaging, but this led to a high breakage rate, which could be completely prevented by the use of CZ® resin vials. Stability studies to date show that the lyophilized product in glass vials is stable for at least 12 months when stored at 2–8°C in the dark and the lyophilized product in CZ resin vials is stable for at least 6 months under these conditions. Photostability testing revealed photolability of AP 5280 drug substance and lyophilized product in both types of primary container, necessitating storage in the dark. The first clinical experiences indicate that the proposed formulation is fully applicable for use in the clinical setting.

Adhesion between polyethylene molding and metal surface-modified with silane coupling agents by use of polyethylene gels

The effects of copper plate surface-treatment with 3-aminopropyltriethoxysilane (APS) on the adhesion between the copper plate and polyethylene plate through polyethylene gel have been investigated by tensile shear test, DSC measurement, and FT-IR measurement. The copper plate was treated with an ethanol–water mixed solvent containing water content of 30 vol% as a solvent of the APS, the polysiloxane structure favorable for the adhesion between polyethylene and copper plate is formed rapidly. The interfacial shear strength goes up to over 8 MPa when treated with the APS solution in concentration of about 5.0 × 10-2 moll-1. The flexible polysiloxane networks formed from the APS solution on copper plate were found to act effectively for the adhesion. Experiments for model substances corresponding to the interphase in the present adhesion on the basis of DSC measurement and FT-IR measurement have revealed that the flexible polysiloxane networks formed from the APS solution and polyethylene chains as an adhesive interpenetrate and interact.

Modification of High-Strength and High-Modulus Polyethylene Fiber Surfaces for the Purpose of Dyeing

We investigated the dyeing properties of polysiloxane networks formed on high-strength and high-modulus polyethylene fiber after hydroxyl groups were introduced onto the fiber surface by chemical treatment. Hydrogen peroxide in o-xylene emulsion in a volume ratio of 1:10 was emulsified by sonication. The emulsion was found to be effective for introduction of hydroxide groups onto the fiber surface. The introduced hydroxide groups reached maximum levels by treatment for approximately 5 min at 80°C. The treatment did not influence the tensile strength of the fiber. Utilizing a polysiloxane network in conjunction with the strong fiber surface formed by treating with 3-aminopropyltriethoxysilane (APS) solution, the dyeing properties of an anionic dye, C.I. Acid Blue 25 was examined. The dyeing resulted in a bluish polyethylene fiber and the color depended upon the duration of treatment with the APS solution. The method proposed in the present study can be used to dye a polyethylene fiber surface.

Effect of β-cyclodextrin on intramolecular charge-transfer emission of 4-aminophthalimide

Steady state and time-resolved studies on the fluorescence of 4-aminophthalimide (AP) in aqueous β-cyclodextrin (CD) solutions are reported. A blue shift of the fluorescence maximum, enhancement of the fluorescence quantum yield and increase in the lifetime of the emitting intramolecular charge-transfer state are observed on addition of CD to an aqueous solution of AP. It is suggested that the elimination of water molecules from the surrounding of the fluorescent probe, as a result of encapsulation, leads to the changes in the photophysical properties. The formation constant of the complex is estimated from the pre-exponential factors of the biexponential decay of the fluorescence and is found to agree reasonably well with that obtained from fluorescence intensity measurements.

Microphase separated semi-interpenetrating polymer networks from atactic polystyrene and methacrylates — a novel route

A new route towards the formation of micro-phase separated semi- interpenetrating polymer networks (semi-IPN's) is described for the system atactic PS in methacrylates. It comprises the arrest of spinodal decomposition of an aPS solution by thermoreversible gelation (vitrification) of the polymer-rich phase. After lowtemperature UV-polymerization and crosslinking of the methacrylate, the phase separated structure is preserved at room temperature. Thus the steps of morphology formation and polymerization are separated.

A global geodetic reference frame from LAGEOS ranging (SL5.1AP)

A summary of the results obtained for a new comprehensive geodetic parameter solution from the analysis of LAGEOS laser ranging data for the period May 1976 to the end of 1982 is presented. Estimates of each component of the polar motion and earth rotation, the station coordinates, the value of the earth's gravitational constant GM, and the elements of the LAGEOS orbit comprise this SL5.1AP solution. The results differ from previously published values primarily through incorporation of more rigorous dynamic models for the ocean and solid earth tides. The precision of the geodetic parameters are on average 5‐marc sec polar motion, 0.2‐ms length of day, better than 5‐cm center‐of‐mass geodetic positioning, 3‐cm global baselines, and 2‐cm regional baselines. An assessment of the contribution of systematic errors in the interstation distance determination is presented.

Inhibition reaction of LiF on the combustion of ammonium perchlorate propellants

Lithium fluoride (LiF) is known as a negative catalyst which acts to reduce the burning rate of ammonium perchlorate (NH 4 ClO 4 : AP) composite propellants. To elucidate the role of LiF, the thermal decomposition process of AP particles with and without LiF was examined using differential thermal analysis, thermogravimetry, photomicrographic observations, and x-ray analysis. A two-stage decomposition process was observed during heating of the mixture of AP and 10% LiF. LiF acts to form a solution of AP and LP (LiClO 4 ) accompanied by an endothermic reaction. In the first-stage decomposition process, the liquified AP decomposes rapidly to form gaseous NH 3 and HClO 4 which react with each other exothermally. In the second-stage decomposition process, the liquified LP decomposes to O 2 and solidified LiCl. The gas phase reaction of AP composite propellants with and without LiF was examined by a microthermocouple technique. For example, the gas phase reaction rate is reduced by as much as 40% by the addition of 0.5% LiF. Thus, the heat feedback from the gas phase to the condensed phase decreases by 10 to 20%. Consequently, the burning rate decreases by 20 to 35%. This reduced gas phase reaction rate is attributed to altered condensed-phase decomposition processes between AP and LiF.

Time-resolved absorption spectroscopic studies on the reaction of conformationally fixed o-(9-fluorenyl)phenylnitrenes

Abstract Laser-flash photolysis studies have been carried out on a solution of ap- and sp-9-(2-azido-4,6-dimethylphenyl)fluorenes (3) in methanol-ether at 25°C. The rates of formation of azanorcaradiene (5) from ap-nitrene (4) ap, and of 9-methoxyfluorene (7) from o-quinoid intermediate (6) were determined. The deuterium isotope effect on the migration of the hydrogen is discussed.