The effects of dextran in residual impurity on trehalose crystallization and formula in food preservation

The residual dextran impurities in the upstream process significantly impact the crystallization of starch-based functional sugar and the related food properties. This study intends to reveal the mechanism of dextran's influence on trehalose crystallization, and build a relationship among the dextran in syrup and the physicochemical and functional properties of trehalose. Instead of incorporating into the crystal lattice, dextran changes the assembly rate of trehalose molecules on crystal surface. The different sensitivity and adsorption capacity of the crystal surface to the chain length of dextran determines the growth rate of crystal surfaces, resulting in different crystal morphology. The bulk trehalose crystals, which were obtained from syrups with short chain dextran, have excellent powder properties, including best flowability (35◦), highest crystal strength (2.7 N), lowest caking rate (62.22 %), and the most uniform mixing with other sweeteners (sucrose/xylitol) in food formulations, achieving more stable starch preservation.

Enhancing physicochemical and functional properties of myo-inositol in crystallization with edible sugar additives

Myo-inositol, referred to as vitamin B8, is an essential nutrient for maintaining human physiological functions. However, the morphology of myo-inositol products is predominantly powder or needle shaped, leading to poor food properties. In this work, three edible sugar additives, i.e. d-glucose, l-arabinose and d-fructose, are adopted in the crystallization of myo-inositol to improve its food properties. The results show that these additives change the morphology of myo-inositol crystals. d-glucose and l-arabinose reduced the aspect ratio of myo-inositol crystals, and d-glucose transformed elongated lamellar myo-inositol crystals into diamond-shaped lamellar crystals. The diamond-shaped lamellar myo-inositol products exhibited outstanding functional food properties. It offered a smoother texture and more pleasant mouthfeel when the products were added to infant formulas and nutraceuticals. When they were applied to functional beverages, the dissolution rate was increased by 35 %. This work provides a theoretical guidance for improving food properties through crystallization and possesses considerable potential for industrialization.

Cuticle properties, wax composition, and crystal morphology of Hami melon cultivars (Cucumis melo L.) with differential resistance to fruit softening

Cuticle wax chemicals are cultivar-dependent and contribute to storage quality. Few research reported on wax analysis between melting flesh-type (MF; 'Jinhuami 25') and nonmelting flesh-type (NMF; 'Xizhoumi 17' and 'Chougua') Hami melons. Chemicals and crystal structures of Hami melon cuticular wax, cell wall metabolism related to fruit melting, and fruit physiology were analyzed to observe wax functions. Results showed that Hami melon cuticle wax predominantly consists of esters, alkanes, alcohols, aldehydes, and terpenoids. MF-type has a lower alkane/terpenoid ratio, concomitant to its higher weight loss and cuticle permeability. Micromorphology of wax crystals appears as numerous platelets with irregular crystals, and the transformation of wax structure in NMF Hami melon is delayed. Waxy components affect cell wall metabolism and physiological quality, which results in the pulp texture difference between MF-type and NMF-type during storage. Results provide a reference for the regulation of wax synthesis in both types of melons.

Effect of moderate hydrostatic pressure on crystallization of palm kernel stearin-sunflower oil model systems

Lipid crystallization under moderate hydrostatic pressure treatments (200 MPa, 20 °C, 1-24 h) was studied in palm kernel stearin (PS 100%) and its blends with sunflower oil (PS 80, 90 % w/w). Hyperbarically-crystallized samples exhibited significantly higher firmness, elastic modulus and critical stress values as compared to those of the samples crystallized at atmospheric pressure. These data indicate that moderate hydrostatic pressure favored the formation of a higher amount of small palm kernel stearin crystals as compared to those formed at atmospheric pressure. Pressurization did not affect fat polymorphism, but was able to enhance nucleation instead of crystal growth. This work clearly demonstrated the efficacy of moderate hydrostatic pressure in steering lipid crystallization, opening interesting possible applications of high-pressure processing technology in the fat manufacturing sector.

Crystal morphology prediction of CL-20 and 1,4-DNI co-crystal at different temperatures

CONTEXT

The morphologies of hexanitrohexaazaisowurtzitane (CL-20) and 1,4-dinitroimidazole (1,4-DNI) co-crystal under vacuum or solvent at different temperatures were predicted. The CL-20/1,4-DNI co-crystal has six important growth crystal planes: (002), (011), (101), (11‒1), (110), (111). The areas of (002), (101), and (011) planes account for a relatively large proportion, which are important crystal planes that affect the crystal morphology. The crystal habits at different temperatures were simulated. The simulation results showed that the crystal plane attachment energy of CL-20 and 1,4-DNI co-crystal increases with the increase of temperature, indicating that the increase of temperature is conducive to the growth of crystal planes. The aspect ratio decreases with the increase of temperature and the morphology of co-crystal becomes more spherical at a higher temperature. The theoretical predictions are in good agreement with the experiment. The simulation results can provide guidance for the crystallization of CL-20/1,4-DNI to obtain a nearly spherical crystal morphology.

METHODS

The CL-20/1,4-DNI unit cell structure was geometrically optimized by the COMPASS force field. The AE model was used to predict the morphology of CL-20/1,4-DNI under vacuum, resulting in the most morphologically important growth planes. Ethyl acetate was selected as the solvent. The interaction energy between the solvent and the crystal plane, and the attachment energies in solvent at 298 K, 320 K, 340 K, 360 K, and 380 K were predicted. The NVT ensemble is used in the molecular dynamics calculation process. The simulation step is 1 fs and the total simulation time is 500 ps. The Andersen thermostat is selected as the temperature control method. In the potential energy calculation, the atom-based and Ewald methods were selected to calculate the van der Waals force and the electrostatic interaction force, respectively.

Preparation and growth mechanism of micro spherical ammonium dinitramide crystal based on ultrasound-assisted solvent-antisolvent method

Micro-sized spherical ammonium dinitramide (ADN) crystals are successfully prepared by a facile ultrasound-assisted solvent-antisolvent recrystallization method without introducing any additives. The influences of the volume ratio of solvent to antisolvent, the antisolvent temperature and the ultrasound power on the micro-morphologies and properties of ADN crystals are studied systematically. The changes of morphology, particle size, crystal structure and melting point of the ADN crystals are characterized through scanning electron microscopy (SEM), laser particle size analyzer (LPSA), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The results show that the optimal experimental parameters for the ADN crystal of spherical morphology are as follows: the volume ratio of solvent to antisolvent is 1:50, the antisolvent temperature is 20 ℃, and the ultrasound power is 70 W. The predicted hexagonal-flake and spherical morphologies for the ADN are close to the experimental morphologies. The growth mechanism of the spherical ADN crystal changes with supersaturation of the ADN solution. As the degree of supersaturation increases, the growth models of the spherical ADN change from the spiral growth to the rough growth, and the morphologies of ADN change from the large-sized ADN ball to the small-sized ADN ball.

Exploring space-energy matching via quantum-molecular mechanics modeling and breakage dynamics-energy dissipation via microhydrodynamic modeling to improve the screening efficiency of nanosuspension prepared by wet media milling

Introduction: The preparation of nanosuspensions by wet media milling is a promising technique that increases the bioavailability of insoluble drugs. The nanosuspension is thermodynamically unstable, where its stability might be influenced by the interaction energy between the stabilizers and the drugs after milling at a specific collision energy. However, it is difficult to screen the stabilizers and the parameters of milling accurately and quickly by using traditional analysis methods. Quantum-molecular mechanics and microhydrodynamic modeling can be applied to improve screening efficiency.Areas covered: Quantum-molecular mechanics model, which includes molecular docking, molecular dynamics simulations, and data on binding energy, provides insights into screening stabilizers based on their molecular behavior at the atomic level. The microhydrodynamic model explores the mechanical processes and energy dissipation in nanomilling, and even combines information on the mechanical modulus and an energy vector diagram for the milling parameters screening of drug crystals.Expert opinion: These modeling methods improve screening efficiency and support screening theories based on thermodynamics and physical dynamics. However, how to reasonably combine different modeling methods with their theoretical characteristics and further multidimensional and cross-scale simulations of nanosuspension formation remain challenges.

The novel matrix protein hic7 of hyriopsis cumingii participates in the formation of the shell and pearl

Shell matrix proteins have important roles in the biomineralization of shells. In this study, we isolated and identified a novel shell matrix protein gene, hic7, from the mussel Hyriopsis cumingii. The cDNA of hic7 was 459 bp long, including a 240-bp open reading frame. It encoded a 79 amino acid-long protein, with amino acids 1-19 constituting the signal peptide. The resulting hic7 is rich in cysteine (16.5%). After removing the signal peptide, the molecular weight was 8.85 kDa and the theoretical isoelectric point was 6.34, indicating that hic7 is a weakly acidic shell matrix protein. Hic7 is mainly expressed in the mantle tissue of H. cumingii. In situ hybridization showed hic7 signals at the edge and dorsal region of the mantle outer fold, indicating that it is related to the formation of the prismatic and nacreous layer of the shell. RNA interference indicated that when hic7 was inhibited by 80%, the crystal morphology of the prism and nacre layers of the shell were irregular and disordered. In addition, the expression of hic7 during the early development of the pearl sac indicated that it has an important role in the transformation of calcium carbonate crystals from a disordered to an orderly deposition pattern. These results suggest that matrix protein hic7 take part in constructing the framework of crystal nucleation and regulating the calcium carbonate crystal morphology of the nacreous and prismatic layers of shells and pearls.

The photothermal stability of CNFs/ZnAl-LDHs composited films: Influence of the crystal morphology of ZnAl-LDHs

The existence of hydroxyl and carboxyl groups makes the photothermal stability of cellulose nanofibers (CNFs) poor and thus limits its scale application. This problem could be solved by doping layered double hydroxides (LDHs) nanopowders with opposite charge on the surface of CNFs. This work mainly focused on investigation of the influence of the crystal morphology of the inorganic ultraviolet shielding agent (i.e. ZnAl-LDHs) on the thermal stability of CNFs/ZnAl-LDHs composited films. The results showed that the morphology of LDHs was positively correlated with the photothermal stability of CNFs-based films. Specially, the ZnAl-LDHs with uniform crystal morphology could be prepared by controlling the molar ratio of Zn/Al at 3:1 and thus enhance the photothermal stability of CNFs-based films without any serious light transmittance deteriorating after doping. This work provided a practical and effective way for preparation of photothermal-stable CNFs-based transparent films for industrial application in the fields of photonics and electronics.

Theoretical insight on effect of DMSO-acetonitrile co-solvent on the formation of CL-20/HMX cocrystal explosive

CL-20/HMX-solvent interface models were established to understand the effect of DMSO-acetonitrile co-solvent on the formation of CL-20/HMX cocrystal. The molecular dynamics simulations were applied to theoretically investigate the interactions of CL-20/HMX cocrystal surfaces and dimethyl sulfoxide/acetonitrile co-solvents. The binding energies were calculated, and the interaction between solvent molecules and CL-20/HMX cocrystal faces was analyzed. The results show that molecular interactions would be affected by the mole ratios of solvent, and the comparison of the binding energies with different mole ratios revealed that dimethyl sulfoxide/acetonitrile with mole ratio of 1:3 favors the formation of CL-20/HMX cocrystal.

Polymer-assisted modification of metal-organic framework MIL-96 (Al): influence of HPAM concentration on particle size, crystal morphology and removal of harmful environmental pollutant PFOA

A new synthesis method was developed to prepare an aluminum-based metal organic framework (MIL-96) with a larger particle size and different crystal habits. A low cost and water-soluble polymer, hydrolyzed polyacrylamide (HPAM), was added in varying quantities into the synthesis reaction to achieve >200% particle size enlargement with controlled crystal morphology. The modified adsorbent, MIL-96-RHPAM2, was systematically characterized by SEM, XRD, FTIR, BET and TGA-MS. Using activated carbon (AC) as a reference adsorbent, the effectiveness of MIL-96-RHPAM2 for perfluorooctanoic acid (PFOA) removal from water was examined. The study confirms stable morphology of hydrated MIL-96-RHPAM2 particles as well as a superior PFOA adsorption capacity (340 mg/g) despite its lower surface area, relative to standard MIL-96. MIL-96-RHPAM2 suffers from slow adsorption kinetics as the modification significantly blocks pore access. The strong adsorption of PFOA by MIL-96-RHPAM2 was associated with the formation of electrostatic bonds between the anionic carboxylate of PFOA and the amine functionality present in the HPAM backbone. Thus, the strongly held PFOA molecules in the pores of MIL-96-RHPAM2 were not easily desorbed even after eluted with a high ionic strength solvent (500 mM NaCl). Nevertheless, this simple HPAM addition strategy can still chart promising pathways to impart judicious control over adsorbent particle size and crystal shapes while the introduction of amine functionality onto the surface chemistry is simultaneously useful for enhanced PFOA removal from contaminated aqueous systems.

Comparative analysis of total wax content, chemical composition and crystal morphology of cuticular wax in Korla pear under different relative humidity of storage

The cuticular wax of Korla pear stored under different relative humidity (0 ± 1 ℃, 50-55%, 70-75% and 90-95%) was examined in terms of total wax content, chemical composition and crystal morphology. The cuticular wax was composed of alkanes, olefins, fatty acids, alcohols, aldehydes, esters and terpenoids. High humidity maintained the content of total wax, alkanes and aldehydes at sufficient levels, especially C₂₉ alkane and C₁₈ aldehyde, which could positively regulate the quality of the pear fruits. Cuticular wax contributes to the capacity of preserving water, maintaining cell wall and delaying senescence. Scanning electron microscopy showed that wax crystals appeared as numerous platelets with irregular ovate crystals, high humidity delayed the transformation of wax structure. Taken together, high humidity delayed the ripening and aging by effectively maintaining wax, which was essential for postharvest storage and provide a reference for the production of synthetic wax for Korla pear fruits.

Crystal morphology prediction of 2,2',4,4',6,6'-hexanitrostilbene (HNS) by molecular scale simulation

The spiral growth model was applied to predict the crystal morphology of 2,2',4,4',6,6'-hexanitrostilbene (HNS). We selected solvents of N,N-dimethylformamide (DMF), N-methyl pyrrolidone (NMP), and nitric acid (NA) to control the crystal morphologies of HNS. Molecular dynamic simulations were used to relax the constructed interface model. The relative growth rate of important face is calculated by the spiral growth expression. The predicted crystal shapes are flaky in three solvents. Only (100), (001), and (011) faces are generated in DMF, NMP, and NA. The aspect ratios of the predicted HNS crystal morphologies in DMF, NMP, and NA are 23.00, 15.45, and 4.85, respectively. In addition, we analyzed the properties on each face using periodic bond chain, molecular arrangement, and roughness model. The excellent agreement between the predicted morphologies and the experimental images is clearly evident. These simulation results can provide guidance for the recrystallization of HNS. Graphical abstract.

Molecular Modeling on Morphology of 3,4-Bis(3-nitrofurazan-4-yl)furoxan Crystals in Dichloroethane or Benzene Mixture Solvents

According to the experiments, DNTF crystallizes in benzene/methylbenzene (1:1), benzene/methylbenzene/ethanol (2:3:5), and sym-dichloroethane solvents into two similar crystal shapes, namely strip and tetrahedral. There is a possibility that solvent changes the crystal morphology. In order to explain this phenomenon, the DNTF growth interface model was constructed according to the actual solution environment. The interaction energy between the solvent phase and the DNTF crystal face was studied by means of molecular dynamics simulation. The crystal morphology of DNTF was predicted using the classical modified attachment energy model (MAE) in benzene, methylbenzene, benzene/methylbenzene (1:1), benzene/methylbenzene/ethanol (2:3:5), and sym-dichloroethane. The results show that the DNTF growths are mainly dominated by the (011), (001), (101), (110), (111), and (11[Formula: see text]) faces in vacuum. However, only a few faces will remain in the solvents, of which the (011) and (101) faces are exposed in benzene, methylbenzene, and benzene/methylbenzene (1:1), and only the (111) faces constitute the crystal shape of the DNTF in benzene/methylbenzene/ethanol (2:3:5) and sym-dichloroethane. The predicted results successfully explained the observed phenomena in the experiment. The simulation results can provide some guidance for the crystallization process of DNTF.

Uncovering the action of ethanol controlled crystallization of 3,4-bis(3-nitrofurazan-4-yl)furoxan crystal: A molecular dynamics study

A computational strategy in consideration of attachment energy, temperature, solubility and supersaturation unravels details of the solvent effect on the crystal morphology. The crystal morphologies were predicted by the advanced screw dislocation growth model. This research sheds much light on the crystal growth mechanisms with the example of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF) in ethanol. The solvation model based on the experiment situation was established into periodic supercell. Molecular dynamics simulation was performed for obtaining the adsorption energy at the equilibrium state of the interface layer. The growth characteristics of relevant growth faces are introduced. At the same time, a periodic bond chains analysis can be applied to the existence and evolution of crystal growth units. The prediction results are in remarkable agreement with the experimental results. We found that crystal morphology of DNTF is composed of (002), (111), (111¯) and (101) faces in ethanol. As the saturation temperature rises, the (101) face becomes smaller and eventually disappears.

Ultrabright Full Color Carbon Dots by Fine-Tuning Crystal Morphology Controllable Synthesis for Multicolor Bioimaging and Sensing

In this paper, two kinds of novel carbon nanocrystals (CNCs) with different crystal morphologies (the branch-chain young sprout form (CM1) and conifer-pine form (CM2)) were obtained in a controllable way. The mechanism of crystal morphological development was explored well. When the two kinds of the CNCs were dissolved in different polar solvents, they voluntarily become "ultrafine crystals" at the moment. After that, the ultrabright full color carbon dots (UBFCCDs) have been preliminarily prepared by fine-controlling. With the evaporation of the solvents, the CNCs crystallized again, which could repeat back and forth many times. After the conditions of preparing for CDs were optimized carefully, the as-prepared CDs exhibit ultrabright effects of multiexcitation and multiemission (from blue to red) and can show unique up-conversion luminescence characteristics under a lower excitation wavelength of 660 nm instead of a near-infrared wavelength of 980 or 808 nm. Significantly, the QY% of the UBFCCDs can reach 78.0%, which is higher than that of the traditional hydrothermal methods of discarding precipitation and carrying out dialysis (QY% = 69.0%). The as-prepared CDs can be used for multicolor biomedical imaging in vivo and in vitro and metal ion sensing and also show their potential value for industrial applications.

Effects of physical properties of nano-sized hydroxyapatite crystals on cellular toxicity in renal epithelial cells

Hydroxyapatite (HAP) is not only a common component of most idiopathic CaOx stones, but also the core of Randall's plaque. HAP is a nest that can induce the formation of Randall's plaques and even kidney stones. We studied the toxic effects and mechanisms of four different types of nano-HAP crystals (H-Sphere, 72.5 nm × 72.5 nm; H-Needle, 37.2 nm × 162.7 nm; H-Rod, 42.3 nm × 115.3 nm; and H-Plate, 145.5 nm × 272.9 nm) on human renal proximal tubular epithelial cells (HK-2). HAP crystals could cause oxidative stress that triggered a series of cell dysfunction problems, resulting in decreased cell viability, loss of cell membrane integrity, cell swelling, and cell necrosis. The toxic effect of HAP was mainly attributed to its entry into cell by endocytosis and its accumulation in the lysosomes, causing the level of intracellular reactive oxygen species (ROS) to rise, the mitochondrial membrane potential (Δψm) to decrease, the lysosomal integrity to be destroyed, and the cell cycle blocked during the G0/G1 phase. The cytotoxicity of the four kinds of HAP crystals was ranked as follows: H-Sphere > H-Needle > H-Rod > H-Plate. The cytotoxicity of each crystal was positively correlated with low absolute zeta potential, conduciveness to internalized morphology, large specific surface area and aspect ratio, and small particle size. These results indicated that nano-HAP could damage HK-2 cells, and the physical properties of HAP crystals play a vital effect in their cytotoxicity.

Apple AP2/EREBP transcription factor MdSHINE2 confers drought resistance by regulating wax biosynthesis

This study showed that AP2/EREBP transcription factor MdSHINE2 functioned in mediating cuticular permeability, sensitivity to abscisic acid (ABA), and drought resistance by regulating wax biosynthesis. Plant cuticular wax plays crucial roles in protecting plants from environmental stresses, particularly drought stress. Many enzymes and transcription factors involved in wax biosynthesis have been identified in plant species. In this study, we identified an AP2/EREBP transcription factor, MdSHINE2 from apple, which is a homolog of AtSHINE2 in Arabidopsis. MdSHINE2 was constitutively expressed at different levels in various apple tissues, and the transcription level of MdSHINE2 was induced substantially by abiotic stress and hormone treatments. MdSHINE2-overexpressing Arabidopsis exhibited great change in cuticular wax crystal numbers and morphology and wax composition of leaves and stems. Moreover, MdSHINE2 heavily influenced cuticular permeability, sensitivity to abscisic acid, and drought resistance.

Assessment of Crystal Morphology on Uptake, Particle Dissolution, and Toxicity of Nanoscale Titanium Dioxide on Artemia salina

Knowledge of nanomaterial toxicity is critical to avoid adverse effects on human and environment health. In this study, the influences of crystal morphology on physico-chemical and toxic properties of nanoscale TiO2 (n-TiO2) were investigated. Artemia salina were exposed to anatase, rutile and mixture polymorphs of n-TiO2 in seawater. Short-term (24 h) and long-term (96 h) exposures were conducted in 1, 10 and 100 mg/L suspensions of n-TiO2 in the presence and absence of food. Anatase form had highest accumulation followed by mixture and rutile. Presence of food greatly reduced accumulation. n-TiO2 dissolution was not significant in seawater (p<0.05) nor was influenced from crystal structure. Highest toxic effects occurred in 96h exposure in the order of anatase > mixture > rutile. Mortality and oxidative stress levels increased with increasing n-TiO2 concentration and exposure time (p<0.05). Presence of food in the exposure medium alleviated the oxidative stress, indicating that deprivation from food could promote toxic effects of n-TiO2 under long-term exposure.

The morphology of salt crystals affects the perception of saltiness

High intake of salt (NaCl) has been associated with risk of non-communicable diseases, including hypertension, cardiovascular disease and stroke. Several strategies for reducing salt in foods are under study, including the relation of crystal morphology on dissolution properties of salt in the mouth. The aim of this paper was to study the dissolution of salt crystals with different morphologies in artificial saliva and to correlate the findings with the perception of saltiness over time. The morphology of five commercial salts was analyzed by scanning electronic microscopy and micro-CT studies. Shape parameters of crystals were determined using images from an optical microscope. Crystal dissolution in artificial saliva was evaluated using video-microscopy and the perception of saltiness was evaluated using sensorial test of time-intensity at standardized sodium content. Salt morphology was correlated well with dissolution rate and certain time-intensity parameters (time to maximum intensity, intensity at maximum and increase angle). Non-cubic and agglomerated crystals, such as Kosher and Maldon salts, were dissolved faster (dissolution rate up to 3.8 times higher) and experienced maximum saltiness (up to 17% more) at shorter times (up to 40% less). Crystal morphology may be a variable to consider to achieve sodium reduction while maintaining salt intensity.

A novel method for the separation of mono and ortho polymorphs of paracetamol in gel matrix

The nucleation control and separation of mono and ortho polymorphs of the important pharmaceutical solid paracetamol were carried out through a crystallization process in gel media for the first time. Crystallization of mono and ortho polymorphic forms of paracetamol was achieved by optimizing the experimental parameters such as the specific gravity, pH, height of the gel column and solute concentration at ambient temperature. The optimized experimental conditions favor the generation of necessary supersaturation responsible for the nucleation of preferred polymorph at different levels in the gel column and also endure the stability of the grown orthorhombic polymorphs at ambient conditions. Accordingly the needle like metastable orthorhombic polymorph nucleates at the top portion of the gel column whereas the prismatic stable monoclinic polymorph nucleates mostly at the bottom level. Morphology of the nucleated polymorphs was analyzed and their crystalline structures were confirmed by PXRD. FTIR analysis revealed the shifting of absorption peaks of few functional groups corresponding to both the polymorphs due to the difference in their structural nature. DSC analysis revealed that the grown ortho polymorph form II transforms to mono form I at 89.47°C while the grown mono form I retains its phase until melting.

Analysis of the structure and morphology of fenoxycarb crystals

In this paper, we have explored the relationship between surface structure and crystal growth and morphology of fenoxycarb (FC). Experimental vs. predicted morphologies/face indices of fenoxycarb crystals are presented. Atomic-scale surface structures of the crystalline particles, derived from experimentally indexed single crystals, are also modelled. Single crystals of fenoxycarb exhibit a platelet-like morphology which closely matches predicted morphologies. The solvent choice does not significantly influence either morphology or crystal habit. The crystal morphology is dominated by the {001} faces, featuring weakly interacting aliphatic or aromatic groups at their surfaces. Two distinct modes of interaction of a FC molecule in the crystal can be observed, which appear to be principal factors governing the microscopic shape of the crystal: the relatively strong collateral and the much weaker perpendicular bonding. Both forcefield-based and quantum-chemical calculations predict that the aromatic and aliphatic terminated {001} faces have comparably high stability as a consequence of weak intermolecular bonding. Thus we predict that the most developed {001} surfaces of fenoxycarb crystals should be terminated randomly, favouring neither aliphatic nor aromatic termination.

Crystal growth, spectral, structural and optical studies of π-conjugated stilbazolium crystal: 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate

Nonlinear optical (NLO) organic compound, 4-bromobenzaldehyde-4'-N'-methylstilbazolium tosylate was synthesized by reflux method. The formation of molecular complex was confirmed from (1)H NMR, FT-IR and FT-Raman spectral analyses. The single crystals were grown by slow evaporation solution growth method and the crystal structure and atomic packing of grown crystal was identified. The morphology and growth axis of grown crystal were determined. The crystal perfection was analyzed using high resolution X-ray diffraction study on (001) plane. Thermal stability, decomposition stages and melting point of the grown crystal were analyzed. The optical absorption coefficient (α) and energy band gap (E(g)) of the crystal were determined using UV-visible absorption studies. Second harmonic generation efficiency of the grown crystal was examined by Kurtz powder method with different particle size using 1064 nm laser. Laser induced damage threshold study was carried out for the grown crystal using Nd:YAG laser.

The Formation of Curved Polymer Crystals: Polychlorotrifluoroethylene

The habits and fine structure of crystals of polychlorotrifluoroethylene (PCTFE) grown from dilute solution were studied as functions of crystallization temperature. The solvent used was a low molecular weight PCTFE oil. The simplest crystals found were monolayered chain folded lamellae formed at 110 °C. These lamellae are planar and possess an unusual texture characterized by the presence of fine channel-like voids in the interior of the crystals. These lamellae do not exhibit well-formed crystal faces but are disc-like in overall shape. At lower crystallization temperatures the crystals take the form of complex arrays of curved lamellae which are aggregated into, among others, watchglass-shaped or hollow spherical objects. The variation of the curvature of the crystals with crystallization temperature is discussed in the light of previous studies of the formation of curved crystals of poly(4-methylpentene-1) and polyoxymethylene.