Crystal Photographs Research Articles

Microcrystallization method use for assessing the content of secondary metabolites of lichens

The paper presents photographs of crystals of fumarprotocetraric, evernic, usninic, solorinic, olivetoric, perlatolinic, physodalic, salazinic, tamnolic acids and atranorin obtained from their acetone extracts of lichens. The shape of the crystals is specific to each substance, and their number, size and degree of aggregation depend on the concentration in the solution. Stellate crystals have atranorine, salazinic and evernic acids, with atranorine having the largest and salacic acid having the smallest; rodshaped branched crystals form solorinic and fumarprotocetraric acids, wider in the first, but longer in the second; the oval shape of crystals in the larger tamnolic and small and narrow perlatolinic acid; usnic, physodalic and olivetoric acids form unique crystal forms prismatic, needle branched and pinnate, respectively. It is possible to observe crystals of secondary metabolites of lichens with a conventional light microscope under a 40 lens without immersion oil. For the subsequent comparative assessment of the amount of substances, it is necessary to standardize the suspension of the studied lichen thallus, use a strictly fixed volume of acetone, view at least four sides of the dried drop on the slide and identify their total number in points, noting the presence, degree of branching and aggregation of crystals into conglomerates.

Double Free: A Promising Route toward Moisture-Stable Hypotoxic Hybrid Perovskites

Double Free: A Promising Route toward Moisture-Stable Hypotoxic Hybrid Perovskites

A World without Echoes

A World without Echoes

Sensitivity of Snowfall Characteristics to Meteorological Conditions in the Yeongdong Region of Korea

This study investigates the characteristics of cold clouds and snowfall in both the Yeongdong coastal and mountainous regions under different meteorological conditions based on the integration of numerical modeling and three-hourly rawinsonde observations with snow crystal photographs for a snowfall event that occurred on 29−30 January 2016. We found that rimed particles predominantly observed turned into dendrite particles in the latter period of the episode when the 850 hPa temperature decreased at the coastal site, whereas the snow crystal habits at the mountainous site were largely needle or rimed needle. Rawinsonde soundings showed a well-defined, two-layered cloud structure along with distinctive wind-directional shear, and an inversion in the equivalent potential temperature above the low-level cloud layer. The first experiment with a decrease in lower-layer temperature showed that the low-level cloud thickness was reduced to less than 1.5 km, and the accumulated precipitation was decreased by 87% compared with the control experiment. The difference in precipitation amount between the single-layered experiment and control experiment (two-layered) was not so significant to attribute it to the effect of the seeder−feeder mechanism. The precipitation in the last experiment by weakening wind-directional shear was increased by 1.4 times greater than the control experiment specifically at the coastal site, with graupel particles accounting for the highest proportion (~62%). The current results would improve snowfall forecasts in complicated geographical environments such as Yeongdong in terms of snow crystal habit as well as snowfall amount in both time and space domains.

A Nonlinear Optical Switchable Sulfate of Ultrawide Bandgap

Nonlinear optical (NLO) switchable materials have attracted intense attention because of their promising applications in optoelectronic devices. However, previous studies are mainly limited to mole...

Positive/Negative Phototropism: Controllable Molecular Actuators with Different Bending Behavior

Herein, a series of molecular actuators based on the crystals of (E)-2-(4-fluorostyryl)benzo[d]oxazole (BOAF4), (E)-2-(2,4-difluorostyryl)benzo[d]oxazole (BOAF24), (E)-2-(4-fluorostyryl)benzo[d]thi...

Design and optimization of production parameters for boric acid crystals with the crystallization process in an MSMPR crystallizer using FBRM® and PVM® technologies

In crystallization studies, newly developed technologies, such as Focused Beam Reflectance Measurement (FBRM) and Particle Vision and Measurement (PVM) are applied for determining on-line monitoring of a representation of the Chord Length Distribution (CLD) and observe the photographs of crystals respectively; moreover recently they are widely used. Properly installed, the FBRM ensures on-line determination of the CLD, which is statistically associated to the Crystal Size Distribution (CSD). In industrial crystallization, CSD and mean crystal size as well as external habit and internal structure are important characteristics for further use of the crystals. In this paper, the effect of residence time, stirring speed, feeding rate, supersaturation level and the polyelectrolytes such as anionic polyacrylamide (APAM) and non-ionic polyacrylamide (NPAM) on the CLD as well as the shape of boric acid crystals were investigated by using the FBRM G600 and the PVM V819 probes respectively in an MSMPR (Mixed Suspension Mixed Product Removal) crystallizer. The CSD and kinetic data were determined experimentally using continuous MSMPR crystallizer running at steady state. The population density of nuclei, the nucleation rate and the growth rate were determined from the experimental population balance distribution when the steady state was reached.

The effect of tailor-made additives on crystal growth of methyl paraben: Experiments and modelling

In this study, methyl paraben (MP) was selected as the model component, and acetaminophen (APAP), p-methyl acetanilide (PMAA) and acetanilide (ACET), which share the similar molecular structure as MP, were selected as the three tailor-made additives to study the effect of tailor-made additives on the crystal growth of MP. HPLC results indicated that the MP crystals induced by the three additives contained MP only. Photographs of the single crystals prepared indicated that the morphology of the MP crystals was greatly changed by the additives, but PXRD and single crystal diffraction results illustrated that the MP crystals were the same polymorph only with different crystal habits, and no new crystal form was found compared with other references. To investigate the effect of the additives on the crystal growth, the interaction between additives and facets was discussed in detail using the DFT methods and MD simulations. The results showed that APAP, PMAA and ACET would be selectively adsorbed on the growth surfaces of the crystal facets, which induced the change in MP crystal habits.

Physical Improvements to a Mesoscopic Cellular Automaton Model for Three-Dimensional Snow Crystal Growth

We motivate and derive the dynamical rules for a computationally feasible three-dimensional cellular automaton model of snow crystal growth. The model improves upon points of weak physical connections identified in other similar models which have produced morphological features observed in many snow crystal photographs. A systematic survey of the morphologies resulting from our model illustrates the degree to which these features persist in our results, and the trends that appear as model parameters are varied.

Use of a thermal imager for snow pit temperatures

Abstract. Weak snow of interest to avalanche forecasting often forms and changes as thin layers. Thermometers, the current field technology for measuring the temperature gradients across such layers – and for thus estimating the expected vapour flux and future type of crystal metamorphism – are difficult to use at distances shorter than 1 cm. In contrast, a thermal imager can provide thousands of simultaneous temperature measurements across small distances with better accuracy. However, a thermal imager only senses the exposed surface, complicating its methods for access and accuracy of buried temperatures. This paper presents methods for exposing buried layers on pit walls and using a thermal imager to measure temperatures on these walls, correct for lens effects with snow, adjust temperature gradients, adjust time exposed, and calculate temperature gradients over millimetre distances. We find lens error on temperature gradients to be on the order of 0.03 °C between image centre and corners. We find temperature gradient change over time to usually decrease – as expected with atmospheric equalization as a strong effect. Case studies including thermal images and visual macro photographs of crystals, collected during the 2010–2011 winter, demonstrate large temperature differences over millimetre-scale distances that are consistent with observed kinetic metamorphism. Further study is needed to use absolute temperatures independently of supporting gradient data.

Experiment Study on Abrasives Performance on Vitrified CBN Wheel

In this paper, accord to effect of CBN abrasives in vitrified wheel, eight kinds CBN abrasives were analyzed for its room performance, microcosmic crystal photographs, high temperature performance and corrosion resistance, by right of single grain pressure-resistant intensity apparatus, SEM and DTA etc advanced apparatus. The test results indicated performance of domestic part single crystal CBN has been reached or exceed overseas same product.

Transmission of solar radiation through the snow cover on floating ice

AbstractSpectral measurements of solar radiation in the band 400–900 nm were performed above and inside the snowpack in two locations in Finland, using a spectroradiometer. The transmittance and extinction coefficient were estimated for different snow layers. Four small candle-shaped photosynthetically active radiation (PAR) sensors were also used to measure the transfer of PAR inside the snowpack. In addition to the light measurements, physical characterization of snow stratigraphy was done, including the thickness, density, hardness (hand test), salinity, and grain size and shape (photographs of crystals). The transmittance varied from <1% (0–12 cm layer) to 80% (0–4 cm layer), and the extinction coefficient was between 0.03 cm−1(4–8 cm layer) and 0.8 cm−1(0–4 cm layer). The physical properties of the snow varied considerably between locations and days. The density of the snow varied between 140 and 480 kg m−3.

Crystals on the cover and validation reports

With this, the first issue of 2010, we proudly initiate the sixth year of publication of Acta Crystallographica Section F and thank our Co-editors for their dedicated service. In keeping with tradition, the cover of this issue is an assembly of the best crystal photomicrographs from crystallization communications published in 2009. This year, we have included such a large number of micrographs that we decided there are simply too many to acknowledge individually. Nevertheless, we gratefully thank the authors for these fine crystal photographs. As a reminder, we would like you, the authors of our articles, to nominate your published crystal photographs for inclusion in the cover. If you would like one of your pictures to be considered as part of a future January cover, you should contact Louise Jones, Technical Editor (lj@iucr.org). Our crystals cover highlights the contribution of crystallization communications to our journal’s scientific content. In 2010 the 13th ICCBM meeting (http://www.iccbm13.ie/) will be held in Trinity College, Dublin. This series of meetings has been the chief venue for scientific interchange on macromolecular crystallization since its inception in 1984, and will undoubtedly be of importance to readers who are interested in crystallization. We also take this opportunity to mention the new Notes for authors which appear in this issue. We and our colleagues at Acta Cryst. D are dedicated to improving the quality of our journals and, accordingly, we are committed in 2010 to full enforcement of the validation requirements in the notes. A future editorial in 2010 will outline journal developments in readiness for the improvements to the validation process at the Worldwide Protein Data Bank, which we applaud and support wholeheartedly.

Experiment Study on Vitrified Bonded Wheels of Quick-Point Grinding

In this paper, grinding performance and Manufacturing process of vitrified CBN wheel were described for Quick-point grinding at 200m/s. In order to insure security rotation of wheel, wheel core was optimized at 200m/s based on ANSYS software. Four kinds of domestic abrasives were tested for their compressive strength, impact toughness, microcosmic crystal photographs, and oxidation temperature, high temperature performance baked at 870 °C, by right of advanced apparatus such as SEM etc. Simultaneity vitrified bonds, wheel segments and adhesive techniques were also discussed. At last, grinding performance of Quick-point Grinding wheel was tested.

Experimental study on scale inhibition performance of a green scale inhibitor polyaspartic acid

Static and dynamic experiments were carried out to validate scale inhibition performance of a green scale inhibitor-polyaspartic acid (PASP). From the static experiment, it was shown that below 60°C, polyaspartic acid is very effective in scale inhibition, with the scale inhibition ratio exceeding 90% with only 3 mg/L PASP for the 600 mg/L hardness solution. For a higher hardness solution of 800 mg/L, the scale inhibition ratio can also reach 90% with 6 and 12 mg/L PASP at 30 and 60°C respectively. The SEM photographs of CaCO3 crystals indicate that the crystal structure transforms from a compact stick-shape to a loose shape so that the scale can be washed away easily instead of being deposited on the heat transfer surface. The dynamic experimental results show that almost no scales formed on the heat transfer surface and the fouling thermal resistance decreases extraordinarily if PASP is added in the solution.

Crystals on the cover

The cover of this issue of Acta Crystallographica Section F is the third one to display a photomontage of crystal micrographs. Section F has committed its cover illustration for the January issue each year to a highlight of its crystallization content with an artful assembly of the best in crystal photomicrographs submitted by authors of crystallization communications published the year before. As a reminder, authors are asked to nominate published photographs of crystals themselves. If authors would like one of their published photographs considered as part of a future crystals cover, they should alert Technical Editor, Louise Jones (lj@iucr.org) by e-mail. The nomination process must be completed by 1 December in order to assemble the final collage in time for the January issue (December photographs will be eligible for consideration for the cover of the following year). Selection factors include focus, contrast, color and symmetry, but, in the final assembly, the chosen photographs must be complementary to one another. The papers providing micrographs for this year’s cover are all from Acta Cryst. F63 (2007) and details are as follows. Top row: putative zinc transporter CzrB from Thermus thermophilus (Hofer et al., pp. 673–677); the fluoresecent probe tetrasulfocyanine in complex with the Fab antibody fragment MOR03268 (Hillig et al., pp. 217–223); and the homing endonuclease I-Dmo-I in complex with its target DNA (Redondo et al., pp. 1017–1020). Middle row: an Escherichia coli tRNAGly acceptor-stem microhelix (Forster et al., pp. 46–48); BigR, a transcription repressor from Xylella fastidiosa (Barbosa et al., pp. 596–598); and PH1010 from Pyrococcus horikoshii OT3 (Shirokane et al., pp. 532–534). Bottom row: the N-terminal region of the human formin-homology protein FHOD1 (Schulte et al., pp. 878–881); the archaeal transcription termination factor NusA (Tanaka et al., pp. 69–73); and Escherichia coli WrbA in complex with its cofactor flavin mononucleotide (Wolfova et al., pp. 571–575). Last year, one of us attended the biennial Recent Advances in Macromolecular Crystallization meeting (http://www.hamptonresearch.com/stuff/RAMC.aspx) in San Diego, California. The strictly small scale, the helpful workshop, the rich program of timely presentations, the inventive tools for encouraging discussion and, above all, the enthusiastic participation of attendees and organizers alike make this a unique and most rewarding experience for everyone who attends. This year, the twelfth in the series of the biennial ICCBM meetings (http://www.iquimica.unam.mx/ICCBM12/) will be held, this one being in Cancun, Mexico. The ICCBM meetings cover the widest range of topics of crystallization import, including, for example, developments in high-throughput methods for structural genomics, and are traditionally preceded by a workshop on basic crystallization methods. These meetings, the RAMC and the ICCBM meetings, are a great service to the crystallization community. The organizers deserve our thanks and support. Anyone with an interest in macromolecular crystallization is encouraged to attend.

Crystallization during the formation of a multicomponent lead-containing borosilicate gel

The processes occurring in the course of drying and gelation of an aqueous solution of a glass-forming material in the Li2O-Na2O-K2O-PbO-B2O3-SiO2-H8C6O7-H4N2CS system, as well as the bulk crystallization accompanying these processes, are investigated using spectral and diffraction analyses. It is revealed that the crystals growing in the bulk of the gel and on the surface of the gel-air boundary have different morphologies: needle-shaped crystals with helical thickenings grow in the bulk of the gel and dendrites are formed on the surface. Analysis of the shadow patterns in photographs of needle-shaped crystals formed in the bulk of the gel has revealed that, in the presence of concentration gradients, eddying flows of the crystallizing compound move to crystallization centers in a vortex manner. This leads to the motion of crystals as a whole toward the gel surface up to the emergence of the crystals on the surface.

Effect of ultrasonic irradiation on the number of acetylsalicylic acid crystals produced under the supersaturated condition and the ability of controlling the final crystal size via primary nucleation

The purposes of this study were to investigate the effects of ultrasound irradiation on the number of crystals formed in an acetylsalicyclic acid crystallization process and to assess the controllability of the final product size via the number of primary nuclei. The number of crystals present after primary nucleation was counted and the relationship between the final product size and the number of crystals was examined. Additionally, the growing ASA crystals were observed, since ultrasound energy not only may control primary nucleation but may also the perfection of the crystal shape. At a high level of ultrasonic energy, ultrasound irradiation increased the average number of crystals, an effect that has been reported often; however, at a low level of ultrasonic energy it decreased the average number of crystals, and moreover, these opposing ultrasonic effects on the number of crystals interchanged at a specific energy threshold. These results reveal two novel phenomena—that there is an energy region where ultrasonic irradiation inhibits primary nucleation, and that a specific amount of ultrasonic energy is needed to activate primary nucleation. On the other hand, the final product size almost depended upon the number of primary nuclei, indicating that the final product size could be controlled via the number of crystals influenced by ultrasound irradiation. According to the photographs of crystals, they were not destroyed by the process. Therefore, it was proposed that ultrasound energy does not destroy the perfection of the crystal shape but only controls primary nucleation under the condition: both short irradiation time and low supersaturated condition.

Extrapolating the skier stability of buried surface hoar layers from study plot measurements

Buried layers of surface hoar pose a challenge to avalanche forecasters in many areas, partly because some layers stabilise quickly and others remain unstable for a month or more. This paper relates the measurements of two surface hoar layers in a study plot, one buried 30 December 1999 and the other buried 21 February 2000, to skier-triggered slab avalanches within 100 km of the study plot in the Columbia Mountains of western Canada. The two surface hoar layers were monitored at a tree-line study slope at Rogers Pass every 4 to 8 days until the end of March 2000. Physical properties of the slab (load, thickness, hardness profile), and weak layer (shear strength, temperature, temperature gradient, crystal size, crystal form) were observed. Approximately once every 2 weeks, the weak layers were photographed in the pit wall to document their texture. On the same days, disaggregated crystals from the weak layers were photographed on a crystal screen. The February 21 layer, which initially consisted of 4–6-mm crystals, was loaded more slowly by snowfall, gained strength and stability more slowly, yielded initially lower stability indices and released many more skier-triggered avalanches than the December 30 layer, which initially consisted of larger, 10–20-mm crystals. Critical study plot values of load, shear strength, and stability are compared with critical values measured adjacent to over 50 skier-triggered slab avalanches. The shear strength of the weak layer, calculated skier stability index Sk 38, layer thickness, and load on the weak layer show potential predictive value for the stabilisation of buried surface hoar layers. While the time series of photographs of separated crystals shows distinct changes, the time series of photographs of the buried surface hoar layers in situ reveals little useful information on textural changes other than thinning of the layers.

Phase diagram of alloy crystal in the exhaustively deionized suspensions of binary mixtures of colloidal spheres

Phase diagrams of liquidlike, alloy crystal-like and amorphous solid-like(AS) structures have been obtained for the exhaustively deionized aqueous suspensions of the binary mixtures of polystyrene or silica spheres. Diameter, polydispersity index (standard deviation of diameter divided by the mean diameter) and size ratio of the binary spheres (diameter of small sphere divided by that of large one) range from 85 to 136 nm, 0.07 to 0.26 and 0.76 to 0.93, respectively. Close-up color photographs of the alloy crystals are taken and the crystal structure has been analysed from reflection spectroscopy. Most of the alloy crystals aresubstitutional solid-solution (sss) type and body-contered cubic lattice structure. Formation of the alloy crystals is attributed to the important role of the expanded electrical double layers in the deionized condition and increase toward unity in the effective size ratio, which is the effective diameter of small sphere including double layer divided by that of large sphere AS structure is formed at the rather high concentrations of two spheres, where the thickness of the electrical double layer is thin and the effective size rado is comparatively small.