Amorphous Pattern Research Articles

Preparation, Dissolution and Characterization of Praziquantel Solid Dispersions.

Solid dispersions of praziquantel (PZQ) containing varying concentrations of polyvinylpyrrolidone (PVP) with different molecular weights (3000, 11000 and 34000) were prepared in an attempt to improve the solubility and dissolution rate of PZQ. The physical characteristics of PZQ, physical mixtures and solid dispersions were investigated by a variety of analytical methods including scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and powder X-ray diffraction (XRD). The solubility of PZQ in the coprecipitate was greater when PVP of a smaller molecular weight was used. The dissolution rate of the drug in the coprecipitate was faster when the ratio of the drug to PVP was smaller (1 : 9). SEM was especially useful in the verification of possible PZQ inclusion in the PVP matrix due to the morphological and physical differences between PZQ and PVP. The physical mixture and solid dispersion DSC scans did not present a clear endothermic peak, perhaps due to low PZQ enthalpy.The dissolution rate was significantly increased when the PZQ : PVP ratio was at least 1 : 5, which agrees with the inclusion of PZQ in the PVP matrix, as observed by SEM, and the amorphous pattern shown by XRD.

Formation of an Amorphous Domain Pattern in Type-II Incommensurate Ferroelectrics

Coarsening of a domain pattern during the cooling process in type-II incommensurate ferroelectrics like NaNO 2 or thiourea is investigated in the framework of two-dimensional discrete lattice model derived from the Ishibashi-Shiba potential. The cooling process is simulated by gradual change of the parameters of potential with time. It has turned out that the resultant domain patterns differ depending on the cooling rate. The present lattice model can satisfactorily reproduce the formation of lamellar and amorphous domain patterns actually observed in NaNO 2 .

H/Z: Why Lesléa Newman Makes Heather into Zoe

H/Z:Why Lesléa Newman Makes Heather into Zoe Elizabeth A. Ford (bio) "Few changes in American mores over the past 50 years have been as dramatic or as salutary as the nation's increased acceptance of homosexuals." —Phillip Lopate, 1997. Consider Lopate's assertion as you read these three fragments trapped in the time capsule of a hot month in a recent summer: 20 August 1995: Denis Donoghue concludes his review of Virtually Normal: An Argument about Homosexuality with a personal comment. He says that his interest in Andrew Sullivan's work, which assesses the current politics of homosexuality, is catalyzed by his affection for his lesbian daughter, "the writer Emma Donoghue," whose homosexuality "does not darken [his] love for her, or qualify the joy [he] takes in her personality, her immense gifts" (26).1 The opening sentence of that paragraph slightly diminishes the power of his declaration: "I am not, in my own person," Donoghue makes clear, "directly caught in this dispute" (26). 25 August 1995: A shopping trip to a split-down-the-middle Carter's outlet leaves me bemused. Although department stores have always separated boys' apparel from girls', surely baby clothing has never been so irrevocably divided, so aggressively gendered. Marooned between two poles of certainty, the layette counter offers the only gender-neutral option, bland infant garments sporting amorphous patterns (not flower shapes, but not airplanes either).2 I imagine the Carter's design team heaving sighs of relief and trashing these insincere either/or ensembles, now that almost all prospective parents choose to know their babies' gender. The word layette (way too feminine) will vanish. 27 August 1995: A pretty little girl grins fetchingly from the Children's Books page of the New York Times Book Review. Catherine Stock's frontispiece accompanies Roger Sutton's review of Too Far Away to Touch, by Lesléa Newman.3 Stock's watercolor still-life shows a gold-framed photo of two faces: a smiling blonde child, eyes closed, being hugged by a tousle-haired young man whose own closed eyes are slightly shadowed. Dark background tones in this illustration foreshadow the content of Newman's text, in which the child tells about her visits with a favorite uncle, who, Sutton explains, is dying of AIDS. The descriptive phrase that Sutton applies to Newman's text could also refer to the watercolor—"poignant, but not sticky." His generally positive review of Newman's book and a similar picture book by Judith Vigna concludes with a contemplative paragraph about purpose: "What are these books for?" he asks. "Will children want to read them or hear them again?" (27). These salvaged fragments may sound like gleanings from an Internet search generated by the terms gay/lesbian, children, literature, and clothing. But I hope to reveal the codes—Barthian and other—that connect these fragments and to use them to explore a central, unspoken anxiety that haunts the conjunction of gay/lesbian issues and children's literature. Eve Kosofsky Sedgwick calls "the experience and identity of gay or proto-gay children" a "fraught space of life-or-death struggle that has been more or less abandoned by constructivist gay theory" (42). Books that present gay or lesbian themes to children may be seen as opening up that "fraught space" to their readers. Ultimately, it is the fear of what children might learn about their own sexual identities, not about the sexuality of adults around them, that makes these books controversial. "Unsubtle, overly didactic" Authors who chose gay themes and who write for children must also choose whether or not to be commercially viable. Those who want to sell books must learn, as Newman seems to have learned, to maintain a "safe" distance between child and gay adult characters. More like a wall than a comfort zone, distance problematizes the treatment of gay themes in children's literature and may keep the genre from reflecting the growing cultural acceptance that Lopate identifies as a contemporary reality. Writers who hope to promote cultural acceptance would be unusual if they did not hope for readers and sales as well. The New York Times Book Review, itself a commodity, affects the transaction...

Synthesis and properties of soluble aromatic polyimides from 2,2?-bis(3,4-dicarboxyphenoxy)-1,1?-binaphthyl dianhydride and aromatic diamines

Aromatic tetracarboxylic dianhydride having crank and twisted noncoplanar structure, 2,2′-bis(3,4-dicarboxyphenoxy)-1,1′-binaphthyl dianhydride, was synthesized by the reaction of 4-nitrophthalonitrile with 2,2′-dihydroxy-1,1′-binaphthyl, followed by alkaline hydrolysis of the intermediate bis(ether dinitrile) and subsequent dehydration of the resulting bis(ether diacid). Binaphthyl-2,2′-diyl–containing novel aromatic polyimides having inherent viscosities up to 0.67 dL/g were obtained by the one-step polymerization process starting from the bis(ether anhydride) and various aromatic diamines. All the polyimides showed typical amorphous diffraction patterns. Most of the polyimides were readily soluble in common organic solvents such as N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), and pyridine. These aromatic polyimides had glass transition temperatures in the range of 280–350°C, depending on the nature of the diamine moiety. All polymers were stable up to 400°C, with 10% weight loss being recorded above 485°C in air. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1937–1943, 1998

Magnetic resonance features of the enigmatic oligodendroglioma.

The authors characterize magnetic resonance (MR) features of oligodendroglioma that permit diagnosis. These features may be used to guide MR stereotactic biopsies. Fifteen patients with mixed oligodendroglioma and four with pure oligodendroglioma were studied on a 1.5-tesla MR unit with contrast and also by computed tomography (CT). All patients had their diagnosis confirmed by light and electron microscopy, and by immunohistochemical staining. The most characteristic finding was a honeycomb tumor matrix (4 of 19) in oligodendroglioma. The most common finding was an amorphous pattern (12 of 19) and the least common was a large cystic pattern (3 of 19). Contrast enhancement most commonly was minimal and dot-like or lacy in appearance (11 of 19), or absent (5 of 19). Calcification was present in the majority (11 of 19). The honeycomb and stippled amorphous patterns reflect the cytoarchitecture of oligodendroglioma and were the most characteristic MR features. The amorphous pattern was the most commonly encountered pattern. There was a wider range of imaging findings on MR compared with CT; the flocculent calcification on CT was typical, but it was not always detected on MR. Including these characteristic areas that appear along the path of the stereotactic biopsy may ensure a correct diagnosis of oligodendroglioma because it most often is seen with another tumor, usually of the astrocytic family. Identifying the oligodendrogliomatous portion of the tumor will influence the therapy. No differences could be found in the MR appearance or biologic behavior of pure versus mixed oligodendrogliomas.

Formation of amorphous electrodeposited Ni-W alloys and their nanocrystallization

Ni-W alloys containing about 5 to 30 at. % W were prepared by electrodeposition. The plating bath for the electrodeposition contained nickel sulfate, citric acid, sodium tungstate and ammonium chloride, and was operated at various bath concentrations and conditions of electrolysis. X-ray diffraction peaks of the deposited alloys broadened with increasing tungsten content and an amorphous pattern appeared at a tungsten content of about 20 at. %. Nanocrystallization behavior of the amorphous Ni-25.0 at. % W alloy has been studied by X-ray diffraction, high resolution transmission electron microscopy and small angle X-ray scattering. The Hall-Petch strengthening mechanism was observed for the hardness extending to a finest grain size of about 10 nm. When the grain size was less than about 10 nm, decrease of the hardness was observed. This decrease may be due to the significant increase of the intercrystalline volume fraction, especially the fraction associated with the triple junction.

Observation of Amorphous Domain Pattern in Ferroelectric Sodium Nitrite

It has been found that, when the sample platelets of sodium nitrite are quenched from above T c to room temperature, strongly anisotropic and amorphous domain patterns appear in addition to the well known stripe pattern. A computer simulation shows that both patterns can be formed from the initial lamellar domain structure through the nucleation and growth of antistripples. The amorphous domain patterns appear when the nucleation rate is high and the growth velocity is low. We infer that the quenching provides such a condition to the thin lamellar domains when the temperature of the sample is rapidly cooled in the process of domain pattern evolution.

Synthesis and characterization of new soluble aromatic poly(urea-imide)s fromN,N'-dimethyl-N,N'-bis(aminophenyl)ureas and aromatic tetracarboxylic dianhydrides

New poly(urea-imide)s having inherent viscosities of 0.26-0.57 dL/g were synthesized in two steps by ring-opening polyaddition of N,N'-dimethyl-N,N'-bis(aminophenyl)ureas to various aromatic tetracarboxylic dianhydrides giving poly(amic acid)s, followed by thermal cyclodehydration. All the poly(urea-imide)s showed amorphous patterns in the wide angle X-ray diffractograms. Most of the poly(urea-imide)s were soluble in organic solvents, especially phenolic solvents such as m-cresol and o-chlorophenol, and the polymers synthesized from the 3,4'-type diamine were more soluble than those from the 4,4'-type monomer. The glass transition temperatures and 10% weight loss temperatures under nitrogen of the poly(urea-imide)s were in the range of 218-263°C and 455-500°C, respectively.

Patterned Garnet Films on Substrates with Ion-Beam Bombarded Micropatterns

AbstractWe report the selected-area epitaxy of rare-earth iron garnet crystalline and amorphous straight ridge patterns, from 4μm to 8μm in width, deposited on Gd3Ga5O12 single crystal substrates. These samples were fabricated via a sputter epitaxial method on substrates that were partially etched by ion-beam bombardment. The strip pattern direction has given the considerable influence on the crystal-graphic formation of the sidewall of the grown ridge. The ridge shapes were similar to results that have been reported for the dissolution forms of garnet crystals in phosphoric acid and the facet of garnet crystals grown from flux. Furthermore, we have successfully grown both an epitaxial garnet film onto an amorphous film and an amorphous straight ridge with a triangular shape surrounded by crystal.

Biodegradable Corn Starch Loose-Fill. II. The Effect of Storage at Different Relative Humidities on the Physical Properties of Loose-Fill

The physical properties of corn starch loose-fill were examined at various relative humidities (r.h.). After 48 h of storage at both 25 and 50% r.h., only a slight change in the dimension and physical properties of the corn starch loose-fill was apparent. A wet environment (75% r.h. for 48 h), however, caused significant shrinkage and the loss of physical properties. The tensile properties, particularly tensile modulus, sharply increased, while the resilience gradually decreased with storage time. Amorphous X-ray diffraction patterns of corn starch loose-fills were transformed into crystalline patterns due to aging at 75% r.h. after 48 h. These changes were attributed to the structural relaxation, which was accelerated by moisture gain. The Tg of corn starch loose-fill decreased with increasing the moisture content in expanded starch. Our proposed model based on Avrami equation was able to describe the time-dependent recrystallization of corn starch by modifying the time-dependent tensile modulus. The growth parameter (n) and time constant (k) for the recrystallization process of corn starch loose-fill were about 3.2 and 8.87 × 10−18 s−1, respectively. If the growth parameter of 3.2 is considered, spherulitic growth of crystallization occurred in the corn starch loose-fill in the wet environment.

Heat treatment of amorphous Al 85Y 5Ni 10 and Al 85Y 10Ni 5 alloys

Microstructural changes during annealing of amorphous Al 85Y 5Ni 10 and Al 85Y 10Ni 5 alloy ribbons have been studied by a combination of differential scanning calorimetry, transmission electron microscopy and X-ray diffractometry. As-solidified melt spun Al 85Y 5Ni 10 consists of some atomic clusters or microcrystals embedded in an amorphous matrix, resulting in a shoulder on the amorphous halo diffraction pattern. The alloy crystallizes by primary crystallization of an fcc α solid solution followed by precipitation of orthorhombic Al 3Ni. As solidified melt spun Al 85Y 10Ni 5 consists of a fully amorphous structure with no shoulder on the amorphous halo diffraction pattern. The alloy crystallizes by primary crystallization of an fcc α solid solution followed by an eutectic reaction to form α and hexagonal A1 3Y.

Curved crystal lattice in resolidified submicron Al lines

The microstructure of Al lines resolidified in an amorphous groove pattern, is investigated by backscatter Kikuchi diffraction, x-ray diffraction, and transmission electron microscopy (TEM). If a temperature gradient is present during cooling, the Al lines do not have the common (111) fiber texture. Instead, the (111) crystal planes are parallel to the vertical sidewalls of the grooves and the crystal lattice shows a remarkable, constant curvature over the entire line length of 1 cm. TEM revealed parallel dislocations in the bulk of the line and small crystallites at the interfaces. It is suggested that the (111) sidewall texture is a consequence of the sidewall area being larger than the bottom area. The observed lattice curvature is explained by a nonisotropic movement of dislocations during cooling.

UV-Vis./NIR and transport studies of chemically synthesized soluble polypyrrole

Doped polypyrrole which is soluble in various organic solvents ( m-cresol, chloroform, DMSO, NMP etc.) is synthesized. Homogeneous solutions prepared from the solvents show different behaviors at near IR region depending on the solvent used. The results may be explained by PPy conformation change depending on polarity and aromatic interaction of solvents and dopants. Amorphous X-ray diffraction pattern is observed in flexible free standing films cast from these solutions. The electrical conductivity of the materials is 10 −2 ~ 10 0 S/cm at room temperature. Temperature dependence of dc conductivity ( σ dc) indicates that these materials show the three dimensional variable range hopping (VRH) model and show the relatively strong localization of charge. From the EPR experiment of PPy-NSA ( m-cresol) sample, the density of state of the system is estimated as ~0.06 states/eV ring.

Electrochemical redox properties of chemically synthesized soluble polypyrrole

The soluble polypyrrole(PPy) was synthesized and its electrochemical properties were investigated. The polymer was synthesized by oxidative coupling of monomers in aq. (NH 4S 2O 8/dodecylbenzene sulfonic acid(DBSA) at 0°C. The polymer was soluble in various organic solvents. The absorption spectrum change of the DBSA-PPy solution depends on the solvent used. Free standing films cast from these solutions showed amorphous X-ray diffraction pattern and electrical conductivity of 0.1~6.0 S/cm at room temperature. Thin PPy films on ITO electrodes showed cyclic voltammograms(CV) which have similar shape to those of the electrochemically prepared one. The electrochemical redox properties of these films may be based on the direct reaction of PPyPPy 2+.

Humidity sensing characteristics of manganese oxide prepared by sol-gel method

Electrolytic manganese dioxide (EMD), which has been commonly used as a cathode material in drycell batteries, catalyst and water puri®cation material, is a typical example of a multifunctional material. Xu and Miyazaki [1, 2], found that EMD derivatives could be utilized for humidity sensor materials [1], and developed a resistance-type humidity sensor with a high sensitivity and selectivity [2]. Recently, a new potential-type humidity sensor consisting of EMD solid electrolyte with two electrodes of different metals, such as Pt=Cu or Pt=Al, was explored [3, 4]. The humidity sensing properties were strongly dependent on the features of manganese oxides such as crystalline structure and powder morphology, so further research was needed for the development of an ef®cient humidity sensing system. The sol±gel process based on inorganic polymerization reaction from molecular precursors has provided a new approach to the preparation of inorganic materials [5]. This process has allowed better control of the characteristics of oxide powders. Bach et al. [6] reported the synthesis of manganese oxides via a sol±gel route in detail. Le Goff et al. [7, 8] investigated the structural and electrochemical properties of sol±gel-derived manganese oxides and revealed that these oxides were promising rechargeable cathodic materials for lithium batteries. In this study, the potential-type humidity sensing characteristics of manganese oxide samples prepared by a sol±gel method were evaluated in comparison with an International Common EMD sample no. 14 (IC no. 14 EMD). The sol±gel-derived manganese oxide powder was prepared by the following method, as reported by Bach et al. [6]. A 0.25 M aqueous potassium permanganate solution was mixed with an organic reducing agent, such as fumaric acid solution. The molar ratio of potassium permanganate to fumaric acid was ®xed at 3. Under this condition, a darkbrown transparent gel of KMnO2 was rapidly formed at room temperature. The gel was ®ltered and dried in air at 90±100 8C, giving a black xerogel powder. This KMnO2 xerogel was treated with a 2.5 M sulphuric acid solution for 5 h at room temperature to remove potassium. After the sulphuric acid treatment, the resulting manganese oxide powder was washed by decanting, neutralized with an ammoniacal aqueous solution, ®ltered and dried in air at 90±100 8C. The potassium content of the sample was analysed using a ame spectrophotometer (Shimadzu AA6400F). The crystal structure was characterized by X-ray diffraction (XRD); Mac Science M03X-HF) using CuKa radiation, and the Brunauer±Emmet± Teller (BET) surface area was measured with an adsorption porosimeter (Micromeritics ASAP 2000). The potential-type humidity sensor constituting a galvanic-type cell system was used in this work. The electrochemical cell system is in the form of Pt=MnOx=Al, where Pt and Al act as the cathode and anode, respectively, and MnOx (manganese oxides) act as the solid electrolyte. To fabricate a sensor element, each of the manganese oxide samples under examination was ground in an agate mortar and wetted with ethanol, then the resulting paste was coated onto a mullite tube (1.0 mm in diameter) with Pt and Al ®lament electrodes (0.25 mm in diameter). The electrodes were embedded in the coated MnOx layer to ensure that an electrical contact was made. The thickness of the MnOx layer was approximately 0.3 mm. The sensor element was placed in a test chamber where the humidity was controllable, as shown in Fig. 1. The electromotive force (EMF) by the galvanic cell-type sensor was measured at room temperature by means of an ADVANTEST-TR2114 digital voltmeter (internal impedance . 10 U), and the impedance of the sensor element containing MnOx was of the order of 10 U [4], which is well within the meaningful range of measuring impedance in this case. A sample of sol±gel-derived manganese oxide produced an almost amorphous XRD pattern, as shown in Fig. 2. The potassium content within this

The synthesis of a 1,1′-bi-2-naphthol-based bis(ether anhydride) and aromatic polyimides derived therefrom

2,2′-Bis(3,4-dicarboxyphenoxy)-1,1′-binaphthyl dianhydride was used as a new monomer with various aromatic diamines to obtain polyimides by the usual two-step method. The bis(ether anhydride) was prepared by a nucleophilic substitution of 1,1′-bi-2-naphthol with N-phenyl-4-chlorophthalimide, N-methyl-4-nitrophthalimide or 4-nitrophthalonitrile in aprotic polar solvent, and subsequent hydrolysis of the resulting bis(ether imide)s or bis(ether dinitrile), and then dehydration of the corresponding tetracarboxylic acid to afford the dianhydride. Most of the obtained polyimides were soluble in chloroform, pyridine, DMF, etc. The polyimide prepared from p-phenylene diamine was partial crystalline, whereas the others showed amorphous patterns in a WAXD study. These polymers have glass transition temperatures between 255–294°C and 5% weight loss temperatures in the range of 502–541°C in nitrogen and 473–537°C in air. © 1997 Elsevier Science Ltd.

The investigation of GaN growth on silicon and sapphire using in-situ time-of-flight low energy ion scattering and RHEED

In-situ time-of-flight low energy ion scattering (TOF-LEIS) and reflection high energy electron diffraction (RHEED) is used effectively to monitor surface structure, major elements, and impurities during substrate annealing, nitridation and thin film growth of GaN on Si and Al 2O 3 substrates by electron-cyclotron-resonance (ECR) assisted MBE. During the annealing process of silicon, a combination of time-of-flight direct recoil spectroscopy (TOF-DRS) and mass spectroscopy of recoiled ions (MSRI) was used to monitor the desorption of surface contaminants such as H, C, and O. A change from a 1 × 1 RHEED pattern of oxygen-covered Si(001) to a 1 × 2 + 2 × 1 RHEED pattern, evidence of a clean Si(001) substrate, was observed. For the case of Al 2O 3(0001), a 1 × 1 RHEED pattern of the hexagonal structure was seen when all major contaminants were removed, as indicated by MSRI. The nitridation of a clean Al 2O 3 surface was followed by RHEED and the formation of an AlN overlayer was confirmed by MSRI. A 1 × 1 RHEED pattern was observed after GaN thin film growth on sapphire, indicating a good crystalline structure. Si nitridation and subsequent deposition of columnar GaN on Si, resulted in an amorphous RHEED pattern. MSRI spectra showed the presence of Si in addition to Ga and N. When nitridation of Si was avoided the resulting GaN film was polycrystalline as observed by RHEED and complete coverage occurred, evidenced by the absence of Si in the MSRI spectra. The results show that a combination of RHEED and TOF-LEIS permit real-time optimization of substrate preparation and thin film growth parameters.

Investigation of GaN deposition on Si, Al2O3, and GaAs using in situ mass spectroscopy of recoiled ions and reflection high-energy electron diffraction

In situ mass spectroscopy of recoiled ions (MSRI) and reflection high-energy electron diffraction (RHEED) are used to monitor the surface structure, and the near surface layer composition during the pre-growth preparation step and the deposition of GaN thin films on Si (001), Al2O3 (0001), and GaAs (001) substrates by electron-cyclotron-resonance (ECR)-assisted molecular beam epitaxy. Due to the high lattice mismatch between GaN thin films and these substrates, the initial nucleation step is found to be critical on the resulting thin film properties. Nitridation of the clean Al2O3 (0001) and GaAs(001) surface is observed by RHEED, and the formation of an AlN/GaN overlayer is confirmed by MSRI. During GaN deposition on Si, Al2O3, and GaAs, MSRI and RHEED are used to follow the growth mode and coverage. If a RHEED pattern from the nucleating GaN overlayer has a cubic or wurtzitic symmetry and the MSRI spectra—which is sensitive to the first few monolayers—shows the presence of Ga and N, only then the growth is layer by layer. Scanning electron microscopy micrographs also show a smooth and continuous surface. If an amorphous RHEED pattern is observed and the presence of the Si (Al, O in the case of Al2O3 and As in the case of GaAs) signal is detected in addition to Ga and N, the growth is columnar. In conclusion, we show that RHEED and MSRI form a powerful combination of thin film surface characterization tools ideally suited for real-time optimization of substrate preparation and thin film growth parameters for the nitride materials system.

Preparation and characterization of poly(imide-amide)s by interfacial condensation

A series of poly(imide-amide)s were synthesized by interfacial condensation of carbomethoxy-iso/terephthaloyl chlorides (I) with aromatic diamines and polycyclic aliphatic diamines. Carbomethoxy-iso/terephthaloyl chlorides, containing approximately 50% para isomer and 50% meta isomer, were synthesized from trimellitic anhydride. The intermediates poly(amide-amic ester)s III had inherent viscosity of 0.1–0.36 dL/g. All poly(amide-amic ester)s were soluble in NMP, DMAc, DMF, and DMSO, except the polymer prepared from 1,6-diaminodiamantane. The poly(amide-amic ester)s were thermally treated to form poly(imide-amide)s. Most of poly(imide-amide)s showed amorphous patterns in x-ray diffraction studies. The glass transition temperatures of these poly(imide-amide)s were in the range of 255–319°C, and the 5% weight loss temperatures in TGA were in the range of 465–540°C in nitrogen. The poly(imide-amide)s (IVc and IVd) from polycyclic aliphatic diamines such as 1,3-diaminoadamantane and 1,6-diaminodiamantane, had good thermal stability, with the temperature at 5% weight loss above 465°C. The poly(imide-amide)s (IVc and IVd) also had high glass transition at 294° and 291°C, respectively. © 1996 John Wiley & Sons, Inc.

Enhanced Aqueous Solubility of Phenolic Antioxidants Using Modified β-Cyclodextrins

AbstractPhenolic antioxidants are useful additives with a possible role in cancer chemoprevention. This study describes inclusion complexation between phenolic antioxidants (butylated hydroxyanisole, BHA; butylated hydroxytoluene, BHT) and hydroxypropyl-β-cyclodextrins (HPB) or hydroxyethyl-β-cyclodextrin (HEB) and their characterization by phase solubility analysis, Xray diffraction and infrared (IR) spectroscopy. The complexes were prepared by shaking an aqueous mixture of the antioxidant with each of the cyclodextrins (1:1 molar) at 40 °C for six days and lyophilizing the resulting clear solution. Each of the complexes dissolved instantaneously in water. Phase solubility analysis indicated a more pronounced increase in the aqueous solubility of BHA compared to that of BHT. Xray diffraction patterns of the antioxidant-cyclodextrin complexes indicated a shift from crystalline pattern of the antioxidant to an amorphous pattern for the complexes. Also, the IR spectra of the BHA-cyclodextrin complexes indic...