Search

This study aims to predict the compression behavior of ultra-high molecular weight polyethylene (UHMWPE) at various temperatures (25, 40, and 55[degrees]C) and strain rates (~[10.sup.-4]/s and ~[10.sup.-2]/s) using a single set of three-network (TN) viscoplastic model parameters. The TN model is made up of three parallel networks: networks A and B use nonlinear springs and dashpots to control the responses of the crystalline phase and confined amorphous phases, respectively, while network C captures the macromolecular amorphous networks using a single nonlinear spring. A single set of TN model parameters captures the yield and post-yield hardening responses of the stress-strain curves at experimental temperatures and strain rates. When these TN model calibrated parameters are used as material property in a commercial finite element tool to simulate UHMWPE compression, the predicted and simulated results match well, showing the model's fidelity. Additionally, the model predicts experiments conducted at 40 and 70[degrees]C with loading rates of ~[10.sup.-3]/s and ~[10.sup.-2]/s, respectively. The study also correlates the deformations of UHMWPE's crystalline structure and macromolecular amorphous networks with its global stress versus strain response by extracting stresses from individual networks of the TN model at different strain rates and temperatures. Highlights * UHMWPE's mechanical behavior predicted by a single set of TN model parameters * TN model predicts mechanical response at various strain rates and temperatures. * TN model explains microstructural crystalline and amorphous phase deformations. KEYWORDS compression properties, numerical simulations, three-network (TN) viscoplastic model, UHMWPE, 1 | INTRODUCTION Ultra-high molecular weight polyethylene (UHMWPE) is one such polymer, which demonstrates an encouraging potential as an impact, chemical, and wear-resistant material. (1) UHMWPE has found diverse applications, [...]

A poly(methyl methacrylate)/Ti[O.sub.2] (PMMA/Ti[O.sub.2]) hybrid was synthesized in the presence of triethylene glycol dimethacrylate as a crosslinking agent. Different types of Ti[O.sub.2] rutile, anatase, and P25 were employed in this study, and the morphology, crystalline structure, particle size, thermal properties, photocatalytic activity, and antibacterial activity were investigated. The results show that the particle size of the PMMA/Ti[O.sub.2] hybrids was in the range of 73.3 nm to 210.0 nm. The morphology of the PMMA/Ti[O.sub.2] hybrid was spherical with a narrow particle size distribution. The thermal properties of the PMMA/ Ti[O.sub.2] hybrid were analyzed using differential scanning calorimetry. The glass transition temperature of the PMMA/Ti[O.sub.2] was higher than that of pristine PMMA. The photocatalytic properties were investigated by monitoring the color changes of methylene blue (MB). It was found that the MB degradation for the PMMA hybrid anatase Ti[O.sub.2] (PMMA/aTi[O.sub.2]) reached 80%, which was similar to that for the PMMA hybrid P25Ti[O.sub.2] at 83% in 60 min. The minimum inhibitory concentrations (MICs) and minimal bactericidal concentrations (MBCs) of the PMMA/Ti[O.sub.2] hybrids were estimated. The MIC of PMMA hybrid anatase Ti[O.sub.2] was 9.65 mg [mL.sup.-1] (P. aeruginosa) and 19.33 mg [mL.sup.-1] (S. aureus) which can inhibit the bacteria. The MBC results of the PMMA/aTi[O.sub.2] were 19.33 mg [mL.sup.-1] for both P. aeruginosa and S. aureus. Highlights * Ti[O.sub.2] nanoparticle encapsulation with poly(methyl methacrylate) via miniemulsion polymerization. * Encapsulated particles exhibit excellent photocatalytic properties. * Triethylene glycol dimethacrylate (TEGDMA) crosslinking ensures stability, enhances photocatalytic property. * The influence of TEGDMA on the hybrid was discussed. KEYWORDS antibacterial, hybrid, miniemulsion, photocatalytic, PMMA, titanium dioxide, 1 | INTRODUCTION Due to the intensive development and popularization of hybrid polymer materials in the past decades, novel hybrid polymers have found applications in diverse fields such as polymer [...]

The formation of spherulites in polymers is a well-known phenomenon; when the polymer is crystallized by cooling from the melt, crystal lamellae grow out from a nucleation site in a spherical pattern. If the material is annealed on a planar surface, and viewed between crossed polarizers in a microscope, a Maltese cross with a banding pattern is observed. Where the crystals grow in a direction not parallel to the polarizers, the sample lights up. Often banding of the lit regions is observed, and is believed to be due to rotations of the crystal lamellae around the growth direction. Because it is well known that polarized Raman spectra respond to crystal orientation, we thought it would be interesting to try to document the relationship between the banding behavior and Raman polarization/orientation behavior. In this column I will show results of such an investigation of spherulites of poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHx) with varying composition., Those of you who follow my column know that PHBHx has been my 'favorite' polymer over the last few years, as PET (polyethylene terephthalate) was for many years previously. PHBHx [...]

Abstract The Kevlar fibers were irradiated at up to 2500 kGy using a 10 MeV electron accelerator. The effects of radiation on the Kevlar fibers were evaluated in detail. The [...]

The synthesis of a series of 2- and 8-substituted 4-amino-7-chloroquinolines is presented. Starting from 4,7-dichloroquinolines, the chloro in the 4-position can be effectively substituted using amino alcohols to yield novel analogues of the antimalarial (hydroxy)chloroquine. Both short-chain (2-aminoethanol) and long-chain (5-[N-ethyl-N-(2-hydroxyethyl)amino]-2-aminopentane) coupling partners can be used. While ketone and nitro functionalities were found to be incompatible with the coupling conditions, electron-donating amino and dimethylamino substituents were tolerated. In addition to characterization in solution using multinuclear NMR spectroscopy and high-resolution mass spectrometry, single-crystal X-ray structures are presented of two 4,7-dichloroquinolines as well as three of the N-alkylated products including a unique species in which a pyrrole heterocycle formed at the 2-position of the quinoline subunit and a rare example of a 4-aza-1,10-phenanthroline. Key words: chloroquine analogues, quinoline synthesis, X-ray crystallography, Introduction Quinoline (benzo[b]pyridine) is a prominent pharmacophore, appearing in numerous biologically active synthetic molecules and natural products including prominent antimalarials such as the cinchona alkaloid quinine and the clinically critical [...]

The synthesis and characterisation (IR, NMR, HR-MS, and X-ray crystallography) of six oxazoline Zn complexes, containing enolate ligands derived from a series of (Z)-1-R-2-(4',4'-dimethyl-2'-oxazolin-2'-yl)-efh-1-en-1-ols (R=[C.sub.6][H.sub.5], [C.sub.6][H.sub.4]-p-N[O.sub.2], [C.sub.6][H.sub.4]-p-O[CH.sub.3], [CF.sub.3], [CH.sub.3], or [CMe.sub.3]) is detailed. All derivatives are air-stable solids of formula Zn[([L.sup.n]).sub.2] and are formed in the presence of the title ligands and [NEt.sub.3]. Reasonable yields (53%-82%) are obtained with the exception of R= [CMe.sub.3] (9%); in this case, by-product formation and high solubility affected complex isolation. Crystallographic characterisation reveals that in all cases the ligands are bound in a [kappa].sup.2]-N, O-bonding motif. Little structural diversity is noted within the series; these complexes are further placed into structural context with related Zn materials containing oxazoline, phenolate, and (or) Schiff base ligands. Key words: oxazoline, coordination complexes, zinc, enolate, X-ray crystal structure, Introduction The naturally occurring Group 12 elements hold a unique position within coordination chemistry due to the overwhelming predominance of the +2 oxidation state. This is, of course, a result [...]

A series of [Tb.sup.3+] doped cubic Mg[Al.sub.2][O.sub.4] green phosphors were synthesized via hydrothermal method followed by a post-annealing process. The variation regularity of phase structure, morphology, particle size and concentration quenching mechanism were investigated. The results showed that the crystal structure of matrix materials was not affected when [Tb.sup.3+] ions were introduced. In addition, the micrometer-sized rods and excellent dispersion of the particles were obtained by adding urea. Under excitation at 377 nm, the phosphors exhibited the characteristic of [Tb.sup.3+] emissions with the peaks located at 488 nm ([.sup.5][D.sub.4] [right arrow] [.sup.7][F.sub.6]), 544 nm ([.sup.5][D.sub.4] [right arrow] [.sup.7][F.sub.5]) and 588 nm ([.sup.5][D.sub.4] [right arrow] [.sup.7][F.sub.4]), respectively. Moreover, based on optical analysis, it can be inferred that electric dipole-dipole (d-d) interaction plays an important role in concentration quenching process of [Tb.sup.3+] ions. The green light emitting phosphor Mg[Al.sub.2][O.sub.4]: [Tb.sup.3+] can be realized by adjusting the concentrations of [Tb.sup.3+], and the optimum concentration of [Tb.sup.3+] ions in Mg[Al.sub.2][O.sub.4] was found to be 0.02. Finally, the average fluorescence decay lifetime and the CIE chromaticity coordinates of [Mg.sub.0.98][Al.sub.2][O.sub.4]:0.02[Tb.sup.3+] phosphor were calculated to be 1.2005 ms and (0.3197 0.4109), respectively. The above results suggest that the developed phosphor could have potential to be used as a single-phase green emission phosphor for near-ultraviolet light-emitting diode (NUV-LED) applications., Aluminate-based luminescent materials activated by rare earth ions are of interest due to their good water resistance, stable chemical properties, high efficiency, and lower cost (1-3). As the use of [...]

Dimensional stability from injected parts can be affected by several factors like cycle conditions, polymer crystallinity, and the masterbatch's colorant or additives. Crystallinity as a Main Player In general, a [...]

X-ray single crystal structure and spectroscopic and photophysical parameters of the titled compound were studied. The titled compound shows thermal stability prior to melting at 126.17 [degrees]C with [DELTA]H value of 109.991 12J[g.sup.-1]. Photophysical parameters include singlet electronic absorption, molar absorption coefficient, oscillator strength, and dipole moment of electronic transition, fluorescence spectra, excited state lifetime, and fluorescence quantum yield for 1-((E)-2-phenylethenyl)-2-(4-(2-((E)-2-phenylethenyl) phenoxy) butoxy) (PPPBB) in different solvents. PPPBB displays a little change in maximum absorption and emission spectra with solvent polarity, indicating a slight change in dipole moment of dye molecules upon excitation. The dipole moments' ([DELTA][mu]) difference between the excited and ground states was obtained from the Lippert-Mataga method. Ground and electronic excited states' geometric optimization was performed using density functional theory (DFT) and time-dependent density functional theory (time dependent-DFT), complemented with spectral findings. A good agreement between theoretical data and experimental observations was found. The net photochemical quantum yield ([[phi].sub.c]) of PPPBB dye was calculated in various solvents. Key words: 1-((E)-2-phenylethenyl)-2-(4-(2-((E)-2-phenylethenyl) phenoxy) butoxy) benzene, 1-(E)-styryl-2-(4-(2-(E)-styrylphenoxy) butoxy) benzene, alkoxy bridged styryl benzene, X-ray single crystal structure, density functional theory TD-DFT, photophysical parameters, photochemical quantum yield, 1. Introduction Fluorescent moieties linked by flexible spacers are a very important class of compounds due to their potential application in nucleic acid staining and detection of nucleic acids in [...]

In this paper, influences of [Bi.sup.3+] doping on the crystal structure and electronic band structure of [Sr.sub.3][MgSi.sub.2][O.sub.8], and charge transfer process from the valence band to [Bi.sup.3+] (CT) and from [Bi.sup.3+] to the conduction band in [Sr.sub.3][MgSi.sub.2][O.sub.8] (MMCT) have been investigated through first principles calculations. The total energy calculations make clear the location of the doped [Bi.sup.3+] in [Sr.sub.3][MgSi.sub.2][O.sub.8] that the doped [Bi.sup.3+] preferred to take up the [Mg.sup.2+] sites and form [BiO.sub.6]. The calculated results of electronic band structure and density of states reveal the constituents that make up the conduction band and valence band of [Sr.sub.3][MgSi.sub.2][O.sub.8] and [Sr.sub.3][Mg.sub.0.875][Bi.sub.0.125][Si.sub.2][O.sub.8], respectively. In addition, a defect level appears in the band gap of [Sr.sub.3][Mg.sub.0.875][Bi.sub.0.125][Si.sub.2][O.sub.8], which is originated from the p orbit of the doped [Bi.sup.3+]. Also, the calculated absorptions of [Sr.sub.3][MgSi.sub.2][O.sub.8] and [Sr.sub.3][Mg.sub.0.875][Bi.sub.0.125][Si.sub.2][O.sub.8] show a gradually shifted absorption band from deep UV region to the blue area with increasing absorption intensity. The above results make clear of the fact that first principles calculations can be useful in investigating the properties of [Bi.sup.3+] doped luminescent materials and designing new kinds of luminescent host materials. Key words: first principles calculations, luminescence materials, phosphors, bismuth, silicates Dans le cadre du present article, nous avons etudie les efets du dopage au [Bi.sup.3+] sur la structure cristalline et la structure des bandes electroniques du [Sr.sub.3][MgSi.sub.2][O.sub.8], le processus de transfert de charge de la bande de valence au [Bi.sup.3+] (transfert de charge) et du [Bi.sup.3+] a la bande de conduction dans le [Sr.sub.3][MgSi.sub.2][O.sub.8] (transfert de charge metal a metal) au moyen de calculs ab initio. Les calculs d'energie totale permettent de determiner clairement l'emplacement des ions [Bi.sup.3+] dopes dans le [Sr.sub.3][MgSi.sub.2][O.sub.8] et d'etablir que les ions [Bi.sup.3+] dopes prennent preferentiellement la place des ions [Mg.sup.2+] pour former du [BiO.sub.6]. Les resultats des calculs de la structure de bande electronique et de la densite des etats revelent les elements constituant la bande de conduction et la bande de valence du [Sr.sub.3][MgSi.sub.2][O.sub.8] et du [Sr.sub.3][Mg.sub.0.875][Bi.sub.0.125][Si.sub.2][O.sub.8], respectivement. En outre, un niveau de defauts apparait dans la bande interdite du [Sr.sub.3][Mg.sub.0.875][Bi.sub.0.125][Si.sub.2][O.sub.8], qui provient de l'orbitale p du [Bi.sup.3+] dope. Nous avons egalement observe par calcul des absorptions du [Sr.sub.3][MgSi.sub.2][O.sub.8] et du [Sr.sub.3][Mg.sub.0.875][Bi.sub.0.125][Si.sub.2][O.sub.8] que la bande d'absorption s'etait deplacee graduellement de la region de l'ultraviolet profond a la zone bleue, et que son intensite d'absorption s'etait accrue. Ces resultats indiquent avec eloquence que les calculs ab initio peuvent etre utiles pour etudier les proprietes des materiaux luminescents dopes au [Bi.sup.3+] et concevoir de nouveaux types de materiaux hotes luminescents. [Traduit par la Redaction] Mots-cles : calculs ab initio, materiaux luminescents, luminophores, bismuth, silicates, Introduction Nowadays, luminescent materials are involved in every aspect in our daily life such as lighting, display, medical image, high energy ray detection, and so on. (1-6) Therefore, designing and [...]

The bis(dialkylphosphino)amines R2PNHPR2 react with elemental halogens X2 in dichloromethane to produce cationic products of the general form [(R)2P(X)-N-(R)2P(X)]+ (R = i-Pr, Ph, and t-Bu; X = Cl, Br, and I). All of the nine possible products have been isolated and characterized using X-ray difraction. The dichloro compounds crystallize as [HCl2]- salts, while the dibromo and diiodo products have been isolated as trihalides, [X3]-. A number of these compounds have been shown to react further with methanol to produce salts containing [(R)2P(OC[H.sub.3])N(R)2P(OC[H.sub.3])]+ cations, some of which have also been characterized using X-ray crystallography. The conversion of [(Ph)2P(I)-N-(Ph)2P(I)][I3] to [(Ph)2P(OC[H.sub.3])-N-(Ph)2P(OC[H.sub.3])][I3] was monitored using [.sup.31]P NMR spectroscopy that revealed a stepwise reaction of the former compound with methanol. The results are discussed within the context of coupled reactions; this is then used to rationalize a mechanism for the formation of a rare catenated bismuth compound we reported previously. We suggest that the formation of the weak Bi-Bi bonds is ofset by a coupled or a connected reaction mechanism, involving an irreversible reaction forming strong P-OR bonds in another of the isolated products. Key words: bis(dialkylphosphino)amines, halogenation, coupled reaction, crystal structure, bismuth Les bis(dialkylphosphino)amines R2PNHPR2 reagissent avec les halogenes elementaires X2 dans le dichloromethane pour former des produits cationiques de forme generale [(R)2P(X)-N-(R)2P(X)]+ (R = i-Pr, Ph, t-Bu; X = Cl, Br, I). Les neuf produits possibles ont ete isoles et caracterises par difraction des rayons X. Les composes dichloro cristallisent sous forme de sels [HCl2]-, tandis que les produits dibromo et diiodo ont ete isoles sous forme de trihalogenures [X3]-. Un certain nombre de ces composes subissent une autre reaction avec le methanol pour produire des sels contenant des cations [(R)2P(OC[H.sub.3])N(R)2P(OC[H.sub.3])]+, dont certains ont egalement ete caracterises par radiocristallographie. Nous avons suivi la conversion du [(Ph)2P(I)-N-(Ph)2P(I)][I3] en [(Ph)2P(OC[H.sub.3])-N-(Ph)2P(OC[H.sub.3])][I3] par RMN [.sup.31]P, qui a revele une reaction par etapes du premier compose avec le methanol. Nous discutons des resultats dans le contexte des reactions couplees; que nous utilisons par la suite pour expliquer le mecanisme de formation hypothetique d'un rare compose de bismuth concatene que nous avons publie anterieurement. Nous posons l'hypothese selon laquelle la formation des liaisons Bi-Bi faibles est compensee par un mecanisme de reaction couplee ou connectee, qui comporte une reaction irreversible formant des liaisons P-OR fortes dans un autre des produits isoles. [Traduit par la Redaction.] Mots-cles : bis(dialkylphosphino)amines, halogenation, reaction couplee, structure cristalline, bismuth, Introduction Ambidentate bis(dialkylphosphino)amines 1(H)-3(H) (Fig. 1) are a class of electron-rich phosphorus ligands with a P-N-P backbone. (1,2) These compounds, here abbreviated by PNP, have been used in a variety [...]

Introduction Biomineralization produces materials such as abalone that are a rich source of inspiration for functional materials due to their stiffness, strength, and toughness. The translucent inner part of an […]

In 3D printing, composite materials have emerged as a groundbreaking frontier, offering unparalleled possibilities in various industries. The composite 3D printing market is projected to soar to $1.73 billion by [...]

In the preparation of polyethylene (PE) microporous membrane, the stretching process of PE/liquid paraffin (LP) blend is of great significance for improving the mechanical properties and optimizing the pore size and its distribution. In this study, we have adopted a method that combines experimental investigation and numerical simulation to explore crystal structure transformation and residual stress distribution of PE matrix during the stretching process. First of all, the X-ray diffraction, small-angle X-ray scattering test, and tensile strength test are used to analyze these PE/LP blend samples that are processed at different stretching temperatures (110[degrees]C, [15[degrees]C, [20[degrees]C, [25[degrees]C) and different stretching ratios (2 * 2, 3 * 3, 4 * 4, 5 * 5). It is found that a higher temperature or larger ratio is beneficial for crystallizing of PE long chains and affecting the tension strength. After the extraction process, the obtained PE microporous membranes have more uniform pore size distribution and an increased pore diameter according to the results of scanning electron microscopy and porosity test. It is attributed to the fact that residual stress is more easily stored in the amorphous region of PE microporous membrane. PE microporous membranes can have higher crystallinity and welldispersed crystal region by controlling a matched temperature and ratio. It is inspired for optimizing the technological parameters in industrial production. KEYWORDS crystallization, numerical simulation, polyethylene, stretching ratio, stretching temperature, 1 | INTRODUCTION Owing to its high mechanical strength, good uniformity, excellent wettability, strong chemical stability, and many other advantages, polyethylene (PE) microporous membrane prepared by the wet process has [...]

To study the effect of the high-frequency vibration time on the mechanical properties of the injection molding workpieces, apply an improved ultrasonic vibrator which contains the original ultrasonic vibrator and the mold insert to change the crystal structure during the melt cooling stage. The crystallinity, crystal perfection, and yield stress characteristics of the workpieces under three injection temperatures were compared with those without ultrasonic vibration. Results manifested that the change of the yield stress and cross-section crystallinity of the sample obeys the Gaussian distribution at a specific ultrasonic vibration time. The maximum yield strength and the maximum change of the workpiece were 39.06 MPa (220[degrees]C, 8 s) and 12.70% (240[degrees]C, 10 s), respectively. With the ultrasonic vibration time increased, the crystallinity of the specimen surface decreased; the transition layer and crystal perfection increased first and then decreased. Therefore, considering the relationship between the ultrasonic vibration time and the yield stress, the vibration effect played a critical role at the initial stage of the ultrasonic vibration; the vibration induced the thermodynamics effect required a certain vibration time. This study contributed to changing the mechanism of crystal structure and yield stress under different ultrasonic vibration time. KEYWORDS cooling, crystallization, injection molding, molecular stacking, surface-core structure, ultrasonic vibration time, 1 | INTRODUCTION The demand for injection molding workpieces in various industrial fields is increasing day by day, and the requirements in performance are also getting higher. Therefore, obtaining high-quality [...]

Terahertz (THz) resonance absorption originates from intermolecular interactions, which are suitable for identifying amino acids with multiple isomers. L-threonine and L-allo-threonine are diastereomers with two characteristic peaks in the effective spectrum range of 1.0-2.3 THz, which are located at 1.42 and 2.14 THz for L-threonine (L-thr) and 1.63 and 2.16 THz for L-allo-threonine (L-allo-thr). Based on the density functional theory (DFT) of the crystal structures of L-thr and L-allo-thr, the vibration frequencies of 1.56, 1.87, 2.16 THz, and 2.22 THz were obtained, corresponding to the THz characteristic peaks. Through vibration model analysis, it was found that lattice and skeleton vibrations mediated by intermolecular hydrogen bonds play a crucial role in the THz response. Studying the experimental absorption spectra of different proportions co-crystallized mixtures and 1:1 physical mixture of L-thr and L-allo-thr, it was found that the characteristic peaks of the physical mixture include the characteristic peaks of the two diastereomers in the THz band, while amino-acid co-crystallized mixtures formed their own characteristic peaks depending on the proportion. The results show that the co-crystallized mixture composition of diastereomers can be quantitatively analyzed by THz time-domain spectroscopy (THz-TDS)., As one of the eight essential proteinogenic amino acids, L-threonine (L-thr) is required for body growth, uric acid metabolism, and the immune system. L-allo-threonine (L-allo-thr) is used as a starting [...]

In this work, the effect of calcium sulfate whisker (CSW) and ultrasonically-modified CSW (UCSW) on the crystal structure and isothermal crystallization of isotactic polypropylene (iPP) is studied by using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and polarized optical microscopy (POM). UCSW obviously increases heterogeneous nucleation. The isothermal crystallization kinetics of pure iPP, iPP/CSW, and iPP/UCSW composites are analyzed by the Avrami method. Although the Avrami exponent (n) of these samples only changed slightly, the half crystallization time ([t.sub.1/2]) indicates that CSW and UCSW decrease the overall crystallization time and increase the crystallization rate ([R.sub.c]). POM results show that most crystals are [beta]-iPP shaped and the spherulite size decreases significantly with the addition of UCSW. The apparent equilibrium temperature of iPP/UCSW composites is lower than that of pure iPP and iPP/CSW composites. The values of [beta]-iPP fold surface free energy ([[sigma].sub.e]) and the nucleation parameter ([K.sub.g]) are much lower than that of [alpha]-iPP for these iPP composites. The content of [beta]-crystal in iPP composites increases due to the addition of UCSW. KEYWORDS composites, crystallization, kinetics, ultrasonic, 1 | INTRODUCTION As well known, isotactic polypropylene (iPP) has been widely used thermoplastic because of its comprehensive properties, such as easy of processing, low density, high heat resistance, recycle [...]

Different advanced techniques including Raman area mapping and Raman thermal imaging have been used to investigate various properties of large area iron oxide thin films deposited by spray pyrolysis on a large area of crystalline silicon substrates under controlled external parameters. Morphological studies reveal that the obtained films acquired the lateral faceted crystalline structure of iron oxide. Together, the Raman and SEM images confirm the presence and large area distribution of the nano crystals of [Fe.sub.2][0.sub.3] phase. Thermal Raman imaging reveals that the obtained iron oxide thin films are robust and thus can be used for appropriate technological applications like electromagnetic shielding. Key words: Raman thermal mapping, spray pyrolysis, Raman imaging, faceted growth, [Fe.sub.2][0.sub.3]. Nous avons utilise differentes techniques d'imagerie de pointe, dont la cartographie de surface Raman et la thermographic Raman, pour etudier les differentes proprietes des couches minces d'oxyde de fer de grande surface deposees par pulverisation pyrolytique sur une grande surface de substrats de silicium cristallin en conditions externes controlees. Des etudes morphologiques revelent que les films ainsi obtenus acquierent la structure cristalline a facettes laterales de l'oxyde de fer. Les resultats d'imagerie Raman et de microscopie electronique a balayage (MEB) confirment ensemble la presence et la distribution etendue de la phase de nanocristaux de [Fe.sub.2][0.sub.3]. L'imagerie thermographique Raman revele que les couches minces d'oxyde de fer obtenues sont robustes et qu'elles peuvent done etre appliquees a des technologies qui requierent cette propriete, telles que le blindage electromagnetique. [Traduit par la Redaction] Mots-cles: thermographic Raman, pyrolyse par pulverisation, imagerie Raman, croissance en facettes, [Fe.sub.2][0.sub.3]., 1. Introduction Several materials and their composites have been known in the electronic and mechanical media for the past several decades (1-5) due to their exceptional properties even in nano [...]

The concept of variable stoichiometry cocrystallization is explored in halogen-bonded systems. Three novel cocrystals of 1,4-diiodotetrafluorobenzene and 3-nitropyridine with molar ratios of 1:1, 2:1, and 1:2, respectively, are prepared by slow evaporation methods. Single-crystal X-ray diffraction analysis reveals key differences between each of the nominally similar cocrystals. For instance, the 1:1 cocrystal crystallizes in the [P2.sub.1]/n space group and features a single chemically and crystallographically unique halogen bond between iodine and the pyridyl nitrogen. The 2:1 cocrystal crystallizes in the P1 space group and features a halogen bond between iodine and one of the nitro oxygens in addition to an iodine--nitrogen halogen bond. The 1:2 cocrystal crystallizes with a large unit cell (V = 9896 [A.sup.3]) in the Cc space group and features 10 crystallographically distinct iodine-nitrogen halogen bonds. Powder X-ray diffraction experiments carried out on the 1:1 and 2:1 cocrystals confirm that gentle grinding does not alter the crystal forms. [.sup.1]H [right arrow] [.sup.13]C and [.sup.19]F [right arrow] [.sup.13]C cross-polarization magic angle spinning (CP/MAS) NMR experiments performed on powdered samples of the 1:1 and 2:1 cocrystals are used as spectral editing tools to select for either the halogen bond acceptor or donor, respectively. Carbon-13 chemical shifts in the cocrystals are shown to change only very subtly relative to pure solid 1,4-diiodotetrafluorobenzene, but the shift of the carbon directly bonded to iodine nevertheless increases, consistent with halogen bond formation (e.g., a shift of +1.6 ppm for the 2:1 cocrystal). This work contributes new examples to the field of variable stoichiometry cocrystal engineering with halogen bonds. Key words: solid-state NMR, X-ray diffraction, halogen bond, cocrystal, polymorphism, stoichiometry, stoichiomorphism. Nous avons etudie le concept de cocristallisation a stoechiometrie variable dans des systemes a liaison halogene. Nous avons prepare par evaporation lente trois nouveaux cocristaux de 1,4-diiodotetrafluorobenzene et de 3-nitropyridine avec des rapports molaires de 1:1, de 2:1 et de 1:2, respectivement. L'analyse par diffraction des rayons X sur monocristal revele des differences importantes entre les cocristaux theoriquement similaires. Par exemple, le cocrystal 1:1 cristallise selon le groupe d'espace [P2.sub.1]/n et presente une seule liaison halogene, sur les plans chimique et cristallographique, entre l'iode et l'azote du groupe pyridyle. Le cocrystal 2:1 cristallise selon le groupe d'espace P1 et presente une liaison halogene entre l'iode et l'un des oxygenes du groupe nitro, en plus de la liaison halogene iode-azote. Le cocristal 1:2 cristallise en formant une grande cellule unitaire (V = 9896 [A.sup.3]) selon le groupe d'espace Cc et presente 10 liaisons halogene iode-azote distinctes sur le plan cristallographique. Des experiences de diffraction des rayons X sur poudre realisees sur les cocristaux 1:1 et 2:1 confirment qu'un broyage leger ne modifie pas les formes cristallines. Nous avons utilise des experiences de RMN [.sup.1]H [right arrow] [.sup.13]C et [.sup.19]F [right arrow] [.sup.13]C a polarisation croisee en rotation a l'angle magique (CP/MAS, cross-polarization/magic angle spinning), realisees sur des echantillons de cocristaux 1:1 et 2:1 sous forme de poudre, comme outils d'edition spectrale pour selectionner l'accepteur ou le donneur de liaison halogene, respectivement. Les deplacements chimiques du carbone-13 dans les cocris-taux ne changent que de facon tres subtile par rapport au 1,4-diiodotetrafluorobenzene solide pur, mais le deplacement du carbone directement lie a l'iode augmente neanmoins, ce qui concorde avec la formation de liaisons halogene (p. ex., un deplacement de +1,6 ppm dans le cas du cocrystal 2:1). Ces travaux apportent de nouveaux exemples au domaine de l'ingenierie des cocristaux a stoechiometrie variable comportant des liaisons halogene. [Traduit par la Redaction] Mots-cles : RMN a l'etat solide, diffraction des rayons X, liaison halogene, cocristal, polymorphisme, stoechiometrie, stoechiomorphisme., Introduction Molecular and ionic solids can adopt a range of forms depending on how they are prepared. (1,2) Such forms include pure crystalline or amorphous phases, hydrates, or solvates. In [...]

In sharp contrast with their amorphous counterparts, crystalline polymers provide a wealth of information on their chain conformation, the packing of the chains in unit-cells, the existence or not of mirror symmetric conformations, on the crystalline lamellae, on the folds linking the crystalline stems, and so forth. Three illustrations of these insights are presented here: (a) the orientation of polymer folds in crystalline lamellae, (b) the complete structural analysis of the alpha phase of isotactic polypropylene by a simple observation of the lamellar morphology, and (c) the so-called lateral spread following secondary nucleation on the growth faces of a polymer crystal. KEYWORDS crystal structure, crystallization, electron microscopy, morphology, polyolefins, 1 | INTRODUCTION This special issue honoring the contributions of Greg McKenna to the understanding of polymer glasses and rheology gives me the opportunity to evoke the lasting friendly relationship [...]

In this work, we have demonstrated a novel bird nest-like nanostructured NiCo.sub.2O.sub.4 (BNNS-NiCo.sub.2O.sub.4) synthesis for the first time by implementing the facile hydrothermal approach and specified via various analytical methods. Particularly, XRD technique presented the data on the crystal structure of BNNS-NiCo.sub.2O.sub.4. Moreover, the bird nest type three-dimensional (3D) hierarchical structure was evident via FESEM analysis. Furthermore, a new modified graphite screen printed electrode is introduced using the synthesized BNNS-NiCo.sub.2O.sub.4. The efficiency of BNNS-NiCo.sub.2O.sub.4 as a sensor modifier for the electrocatalytic oxidation of mangiferin in aqueous solutions was examined via chronoamperometry, cyclic voltammetry and differential pulse voltammetry. The outcomes demonstrated that the application of the developed electrode (BNNS-NiCo.sub.2O.sub.4/screen printed electrode (SPE)) in electrooxidation of mangiferin (pH 7.0) results in high anodic peak currents. Mangiferin oxidation peak potential at the BNNS-NiCo.sub.2O.sub.4/SPE surface was determined at 310 mV, which was approximately 120 mV less compared to the oxidation potential at the SPE surface under identical circumstances. In addition, the peak current was approximately two times higher at the BNNS-NiCo.sub.2O.sub.4/SPE surface in comparison to that of the SPE. The associated linear response range and detection limit were determined as 0.01-800 and 0.04 [mu]M, respectively. The adjusted electrode was successfully applied to determine mangiferin in real specimens exhibiting favorable results., Author(s): Mohammad Rahimipour [sup.1], Azar Bagheri Gh. [sup.2], Seyed Jamilaldin Fatemi [sup.3] Author Affiliations: (1) grid.411463.5, 0000 0001 0706 2472, Department of Chemistry, Central Tehran Branch, Islamic Azad University, , [...]

The [sigma].sub.2 receptor has attracted intense interest in cancer imaging.sup.1, psychiatric disease.sup.2, neuropathic pain.sup.3-5 and other areas of biology.sup.6,7. Here we determined the crystal structure of this receptor in complex with the clinical candidate roluperidone.sup.2 and the tool compound PB28.sup.8. These structures templated a large-scale docking screen of 490 million virtual molecules, of which 484 compounds were synthesized and tested. We identified 127 new chemotypes with affinities superior to 1 [mu]M, 31 of which had affinities superior to 50 nM. The hit rate fell smoothly and monotonically with docking score. We optimized three hits for potency and selectivity, and achieved affinities that ranged from 3 to 48 nM, with up to 250-fold selectivity versus the [sigma].sub.1 receptor. Crystal structures of two ligands bound to the [sigma].sub.2 receptor confirmed the docked poses. To investigate the contribution of the [sigma].sub.2 receptor in pain, two potent [sigma].sub.2-selective ligands and one potent [sigma].sub.1/[sigma].sub.2 non-selective ligand were tested for efficacy in a mouse model of neuropathic pain. All three ligands showed time-dependent decreases in mechanical hypersensitivity in the spared nerve injury model.sup.9, suggesting that the [sigma].sub.2 receptor has a role in nociception. This study illustrates the opportunities for rapid discovery of in vivo probes through structure-based screens of ultra large libraries, enabling study of underexplored areas of biology. Crystal structures of the [sigma].sub.2 receptor are determined and used to perform a docking screen of nearly 500 million molecules, identifying [sigma].sub.2-selective ligands and providing insight into the role of [sigma].sub.2 in neuropathic pain., Author(s): Assaf Alon [sup.1] , Jiankun Lyu [sup.2] , Joao M. Braz [sup.3] , Tia A. Tummino [sup.2] [sup.4] , Veronica Craik [sup.3] , Matthew J. O'Meara [sup.5] , Chase [...]

With polymer pipes being used more commonly, performance requirements are increasing. Studies on the enhancement of mechanical properties of polymer pipes are particularly important. In this study, a self-designed annular expansion pipe extruder head was used to enhance the mechanical properties of HDPE pipes. Different morphologies of the HDPE pipes were produced under different processing conditions. When the extrusion angle was 30[degrees] (P30), the best mechanical properties were obtained. The hoop tensile strength and axial tensile strength were 14.5% and 41.0% higher, respectively, compared with the specimen without expansion (P0). This improvement of mechanical properties can be attributed to several reasons. First, the processing parameters of P30 reached the threshold shear rate and strain for shish-kebab formation, as shown by scanning electron microscopy. Second, P30 has the highest orientation parameter and crystallinity of 0.679 and 67.27%, respectively, from 2D wide-angle diffraction (WAXD). Polarized FTIR shows the same trend as 2DWAXD. Third, the outer bamboo-like self-reinforced structure is formed inside the pipe at 30[degrees] expansion angle while the core layer has a well-formed crystal structure; the special structure improves the overall performance of HDPE pipe. This method can be utilized in large-scale industrial production. KEYWORDS crystallization, extrusion, orientation, 1 | INTRODUCTION Owing to their good performance and affordable price, polyethylene pipes are widely used in various fields. They have the following advantages over steel pipes: light weight, good [...]

The Avalon Peninsula on the island of Newfoundland, Canada, defined as the type zone of Avalonia, is believed to have been impacted by several orogenetic and deformation events since the Neoproterozoic. Previous studies have determined that the lowest degree of metamorphism reached in the successions was of the prehnite--pumpellyite or greenschist facies. We sampled and measured 13 mainly clastic sedimentary sections ranging from the late Ediacaran to the Early Ordovician and analyzed the illite 'crystallinity' of 331 samples using the Kubler index. Our results show that the occurrence of diagenetic zones relates to lithology, age and burial depth, and regional setting. Samples adjacent to the fault zones bounding the Holyrood Horst experienced the highest degree of metamorphism (anchizone) in the study area. The lowest degree of thermal alteration occurs in the high stratigraphic sections at the centre of the horst structure where shallow diagenetic conditions are preserved. Fault zones, which were probably active during at least the Acadian Orogeny, may have served as potential paths for hot fluids in bounding areas of the horst, whereas the centre of the horst remained almost unaffected by any metamorphic overprint. The thermal impact decreases from the Bonavista Peninsula west of the study area from greenschist facies to anchizonal and diagenetic. The study area experienced lower metamorphic conditions than those in the major regions of Avalonia south of the study area, namely the mainland of New Brunswick and Maine and eastward in Europe, but is in part consistent with a few other areas of Avalonia, such as the Mira Terrane and the Antigonish Highlands in Nova Scotia. Key words: illite 'crystallinity', Kubler index, diagenesis, Holyrood Horst, Avalon Peninsula, southeastern Newfoundland. La peninsule dAvalon (Terre-Neuve, Canada), definie comme etant la region type de lAvalonie, aurait subi les effets de plusieurs episodes orogeniques et de deformation depuis le Neoproterozoique. Des etudes passees ont determine que le metamorphisme le plus faible atteint durant ces episodes est au facies prehnite-pumpellyite ou des schistes verts. Nous avons echantillonne et mesure 13 coupes sedimentaires principalement clastiques allant de l'Ediacarien tardif a l'Ordovicien precoce et analyse la << cristallinite >> de l'illite de 331 echantillons a l'aide de l'indice de Kubler. Nos resultats demontrent que la presence de zones diagenetiques est reliee au type de roche, a l'age et a la profondeur d'enfouissement, respectivement, et au contexte regional. Des echantillons attenants aux zones de faille bordant le horst de Holyrood ont subi le metamorphisme le plus intense (anchizone) dans la region d'etude. Le degre le plus faible d'alteration thermique est observe dans les coupes stratigraphiques hautes situees au centre de la structure de horst, ou des conditions de diagenese peu profonde sont preservees. Des zones de faille, a tout le moins probablement actives durant l'orogenese acadienne, pourraient avoir servi de voies d'ecoulement de fluides chauds dans les zones bordant le horst, alors que le centre de ce dernier est demeure presque exempt de tout effet du metamorphisme. L'impact thermique diminue a partir de la peninsule de Bonavista, a l'ouest de la region d'etude, passant du facies des schistes verts a l'anchizone a la zone diagenetique. La region d'etude a subi des conditions de metamorphisme plus faibles que de grands secteurs de l'Avalonie au sud, dans la partie continentale du Nouveau-Brunswick et du Maine et plus a lest en Europe, mais qui concordent du moins partiellement avec celles de quelques autres regions de l'Avalonie, comme le terrane de Mira et les hautes terres d'Antigonish en Nouvelle-Ecosse. [Traduit par la Redaction] Mots-cles: cristallinite de l'illite, indice de Kubler, diagenese, horst de Holyrood, peninsule d'Avalon, sud-est de Terre-Neuve., Introduction The upper Ediacaran and lower Palaeozoic rocks of the Avalon Peninsula on the island of Newfoundland, Canada, have been studied for decades (e.g., Howell 1925; Hutchinson 1962; Fletcher 1972, [...]

What particular mechanical properties can be expected for materials composed of interlocked backbones has been a long-standing issue in materials science since the first reports on polycatenane and polyrotaxane in the 1970s.sup.1-3. Here we report a three-dimensional porous metal-organic crystal, which is exceptional in that its warps and wefts are connected only by catenation. This porous crystal is composed of a tetragonal lattice and dynamically changes its geometry upon guest molecule release, uptake and exchange, and also upon temperature variation even in a low temperature range. We indented.sup.4 the crystal along its a/b axes and obtained the Young's moduli of 1.77 [plus or minus] 0.16 GPa in N,N-dimethylformamide and 1.63 [plus or minus] 0.13 GPa in tetrahydrofuran, which are the lowest among those reported so far for porous metal-organic crystals.sup.5. To our surprise, hydrostatic compression showed that this elastic porous crystal was the most deformable along its c axis, where 5% contraction occurred without structural deterioration upon compression up to 0.88 GPa. The crystal structure obtained at 0.46 GPa showed that the catenated macrocycles move translationally upon contraction. We anticipate our mechanically interlocked molecule-based design to be a starting point for the development of porous materials with exotic mechanical properties. For example, squeezable porous crystals that may address an essential difficulty in realizing both high abilities of guest uptake and release are on the horizon. A rubber-like, metal-organic crystal is reported with a mechanically interlocked catenane backbone, which could allow for easy guest molecule uptake and release., Author(s): Wenjing Meng [sup.1] [sup.8] , Shun Kondo [sup.2] , Takuji Ito [sup.3] , Kazuki Komatsu [sup.4] , Jenny Pirillo [sup.5] , Yuh Hijikata [sup.5] , Yuichi Ikuhara [sup.2] , [...]

The precise stacking of different two-dimensional (2D) structures such as graphene and MoS.sub.2 has reinvigorated the field of 2D materials, revealing exotic phenomena at their interfaces.sup.1,2. These unique interfaces are typically constructed using mechanical or deposition-based methods to build a heterostructure one monolayer at a time.sup.2,3. By contrast, self-assembly is a scalable technique, where complex materials can selectively form in solution.sup.4-6. Here we show a synthetic strategy for the self-assembly of layered perovskite-non-perovskite heterostructures into large single crystals in aqueous solution. Using bifunctional organic molecules as directing groups, we have isolated six layered heterostructures that form as an interleaving of perovskite slabs with a different inorganic lattice, previously unknown to crystallize with perovskites. In many cases, these intergrown lattices are 2D congeners of canonical inorganic structure types. To our knowledge, these compounds are the first layered perovskite heterostructures formed using organic templates and characterized by single-crystal X-ray diffraction. Notably, this interleaving of inorganic structures can markedly transform the band structure. Optical data and first principles calculations show that substantive coupling between perovskite and intergrowth layers leads to new electronic transitions distributed across both sublattices. Given the technological promise of halide perovskites.sup.4, this intuitive synthetic route sets a foundation for the directed synthesis of richly structured complex semiconductors that self-assemble in water. Using organic molecules as directing groups, a wide range of perovskite heterostructures are shown to self-assemble in solution to yield single crystals., Author(s): Michael L. Aubrey [sup.1] , Abraham Saldivar Valdes [sup.1] , Marina R. Filip [sup.2] [sup.3] [sup.4] , Bridget A. Connor [sup.1] , Kurt P. Lindquist [sup.1] , Jeffrey B. [...]

The expansion of deformation-induced crystallization of polypropylene (PP) pipes was studied. The crystal structure and melting characteristics of the samples after expanding at different expansion strains and expansion temperatures were analyzed. The results showed that the ciystallinity was improved when the PP pipes were expanded, and the expansion effect made the crystal structure more perfect while the expanding temperature did not exceed the crystallization temperature. However, once expanding temperature exceeded crystallization temperature, some [beta] lamellae crystal were stretched and transformed into a crystals structure. It showed that the expansion effect could cause the crystal phase transformation of the sample. In addition, when the expanding strain was less than 15%, the [beta] crystal diffraction peak intensity of the sample decreased, but the a crystal diffraction peak intensity increased, and the original sparse distribution lamellae structure gradually became compact. With the expanding strain continued to increase, the oriented molecular chains underwent stress relaxation, which hindered the conversion of [beta] crystals to a crystals. The oriented crystal structure formed by the crystal phase transformation made the PP pipe have excellent tensile and impact strength. As a result, the hoop tensile strength is increased by 13%, and the impact strengths are increased by 36%. KEYWORDS expanding, phase transformation, PP pipe, [beta] crystals, 1 | INTRODUCTION As we all know, polypropylene is widely used in packaging, home appliances, and automobiles due to its good mechanical properties and easy processing and molding. [1-4] As [...]

N,N'-dicyclohexyl-2,6-naphthalenedicarboxamide, a commercial nucleating agent, can dissolve into molten polypropylene (PP) and self-organize into needle-like crystals when the melt temperature reaches 260[degrees]C. As temperature decreases, PP molecules crystallize on the surface of the needle-like crystals with their c-axis perpendicular to the long axis of the crystal. Under a flow field in injection molding, PP chains are parallel or perpendicular to the flow direction at different depths owing to the difference in crystallization kinetics and applied shear rate in the melt, forming a plywood-like material. This unique structure can simultaneously improve the toughness and strength of plastic parts. Herein, we present a novel method of producing high-performance plastic articles based on general plastics by manipulating their morphology and structure. KEYWORDS crystal structures, injection molding, mechanical properties, orientation, poly(propylene) (PP), structure-property relations, 1 | INTRODUCTION Plywood is composed of piled veneers in which the wood fibers of adjacent piles are perpendicular to each other. This particular structure ensures that the material is [...]

Background Interferon and nucleos(t)ide analogues are current therapeutic treatments for chronic Hepatitis B virus (HBV) infection with the limitations of a functional cure. Chrysin (5, 7-dihydroxyflavone) is a natural flavonoid, known for its antiviral and hepatoprotective activities. However, its anti-HBV activity is unexplored. Methods In the present study, the anti-hepatitis B activity of chrysin was investigated using the in vitro experimental cell culture model, HepG2 cells. In silico studies were performed where chrysin and lamivudine (used here as a positive control) were docked with high mobility group box 1 protein (HMGB1). For the in vitro studies, wild type HBV genome construct (pHBV 1.3X) was transiently transfected in HepG2. In culture supernatant samples, HBV surface antigen (HBsAg) and Hepatitis B e antigen (HBeAg) were measured by enzyme-linked immunosorbent assay (ELISA). Secreted HBV DNA and intracellular covalently closed circular DNA (cccDNA) were measured by SYBR green real-time PCR. The 3D crystal structure of HMGB1 (1AAB) protein was developed and docked with the chrysin and lamivudine. In silico drug-likeness, Absorption, Distribution, Metabolism, Excretion and Toxicity (ADMET) properties of finest ligands were performed by using SwissADME and admetSAR web servers. Results Data showed that chrysin significantly decreases HBeAg, HBsAg secretion, supernatant HBV DNA and cccDNA, in a dose dependent manner. The docking studies demonstrated HMGB1 as an important target for chrysin as compared to lamivudine. Chrysin revealed high binding affinity and formed a firm kissing complex with HMGB1 ([DELA]G = - 5.7 kcal/mol), as compared to lamivudine ([DELA]G = - 4.3 kcal/mol), which might be responsible for its antiviral activity. Conclusions The outcome of our study establishes chrysin as a new antiviral against HBV infection. However, using chrysin to treat chronic HBV disease needs further endorsement and optimization by in vivo studies in animal models. Graphical Abstract Keywords: Hepatitis B virus, Chrysin, CccDNA, HMGB1, In silico, Author(s): Sajad Ahmad Bhat[sup.1], Syed Kazim Hasan[sup.1], Zahoor Ahmad Parray[sup.1], Zaheenul Islam Siddiqui[sup.1], Shabnam Ansari[sup.1,2], Ayesha Anwer[sup.1], Saniya Khan[sup.1], Fatima Amir[sup.1,3], Mahboubeh Mehmankhah[sup.1], Asimul Islam[sup.1], Zarrin Minuchehr[sup.4] and Syed Naqui [...]