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Recent studies have highlighted the biological significance of exosomes and m6A modifications in immunity. Nonetheless, it remains unclear whether the m6A modification gene in exosomes of body fluid has potential roles in the tumor microenvironment (TME). Herein, we identified three different m6A-related exosomal gene modification patterns based on 59 m6A-related exosomal genes, which instructed distinguishing characteristics of TME in colon cancer (CC). We demonstrated that these patterns could predict the stage of tumor inflammation, subtypes, genetic variation, and patient prognosis. Furthermore, we developed a scoring mode—m6A-related exosomal gene score (MREGS)—by detecting the level of m6A modification in exosomes to classify immune phenotypes. Low MREGS, characterized by prominent survival and immune activation, was linked to a better response to anti-PDL1 immunotherapy. In contrast, the higher MREGS group displayed remarkable stromal activation, high activity of innate immunocytes, and a lower survival rate. Hence, this work provides a novel approach for evaluating TME cell infiltration in colon cancer and guiding more effective immunotherapy strategies.

N6-methyladenosine (m6A) is the most prevalent RNA epigenetic regulator in cancer. However, the understanding of m6A modification on lipid metabolism regulation in colorectal cancer (CRC) is very limited. Here, we observed that human CRCs exhibited increased m6A mRNA methylation mediated by dysregulation of m6A erasers and readers. By performing methylated RNA-immunoprecipitation sequencing (MeRIP-seq) and transcriptomic sequencing (RNA-seq), we identified DEGS2 as a downstream target of m6A dysregulation. Overexpression or knockdown of DEGS2 confirmed the role of DEGS2 in proliferation, invasion and metastasis of CRC both in vitro and in vivo. Mechanistic studies identified the specific m6A modification site within DEGS2 mRNA, and mutation of this target site was found to drastically enhance the proliferative and invasive ability of CRC cells in vitro and promote tumorigenicity in vivo. Lipidome analysis showed that lipid metabolism was dysregulated in CRC. Moreover, ceramide synthesis was suppressed due to DEGS2 upregulation mediated by m6A modification in CRC tissues. Our findings highlight that the function of DEGS2 m6A methylation in CRC and extend the understanding of the importance of RNA epigenetics in cancer biology.

Thermodynamic/dynamic modeling of liquid immiscibility in silicates is seriously hindered due to lack of in situ investigation on the structural evolution of the melt. In this work, atomic-scale structural evolution of a classic binary silicate immiscible system, SiO2–TiO2, is tracked by in situ high energy X-ray diffraction (HE-XRD). It is found that both the configuration of [SiO] and the polymerization between them are closely coupled with embedment and extraction of the metallic cations (Ti4+). [SiO] monomer goes through deficit-oxygen and excess-polymerization before liquid‒liquid separation and enables self-healing after liquid‒liquid separation, which challenges the traditional cognition that [SiO4] monomer is immutable. Ti4+ cations with tetrahedral oxygen-coordination first participate in the network construction before liquid separation. The four-fold Ti–O bond is broken during liquid separation, which may facilitate the movement of Ti4+ across the Si–O network to form TiO2-rich nodules. The structural features of nodules were also investigated and they were found highly analogous to that of molten TiO2, which implies a parallel crystallization behavior in the two circumstances. Our results shed light on the structural evolution scenario in liquid immiscibility at atomic scale, which will contribute to constructing a complete thermodynamic/dynamic framework describing the silicate liquid immiscibility systems beyond current models.

Recent studies have highlighted the biological significance of exosomes and m

Lethal intestinal tissue toxicity is a common side effect and a dose-limiting factor in chemoradiotherapy. Chemoradiotherapy can trigger DNA damage and induce P53-dependent apoptosis in LGR5+ intestinal stem cells (ISCs). Gamma-aminobutyric acid (GABA) and its A receptors (GABAAR) are present in the gastrointestinal tract. However, the functioning of the GABAergic system in ISCs is poorly defined. We found that GABAAR α1 (GABRA1) levels increased in the murine intestine after chemoradiotherapy. GABRA1 depletion in LGR5+ ISCs protected the intestine from chemoradiotherapy-induced P53-dependent apoptosis and prolonged animal survival. The administration of bicuculline, a GABAAR antagonist, prevented chemoradiotherapy-induced ISC loss and intestinal damage without reducing the chemoradiosensitivity of tumors. Mechanistically, it was associated with the reduction of reactive oxygen species–induced DNA damage via the L-type voltage–dependent Ca2+ channels. Notably, flumazenil, a GABAAR antagonist approved by the U.S. Food and Drug Administration, rescued human colonic organoids from chemoradiotherapy-induced toxicity. Therefore, flumazenil may be a promising drug for reducing the gastrointestinal side effects of chemoradiotherapy.

Colorectal cancers (CRCs) exhibit differences in incidence, pathogenesis, molecular pathways, and outcome depending on the location of the tumor. The transcriptomes of 27,927 single human CRC cells from 3 left-sided and 3 right-sided CRC patients were profiled by single-cell RNA-Seq (scRNA-Seq). Right-sided CRC harbors a significant proportion of exhausted CD8+ T cells of a highly migratory nature. One cluster of cells from left-sided CRC exhibiting states preceding exhaustion and a high ratio of preexhausted/exhausted T cells were favorable prognostic markers. Notably, we identified a potentially novel RBP4+NTS+ subpopulation of cancer cells that exclusively expands in left-sided CRC. Tregs from left-sided CRC showed higher levels of immunotherapy-related genes than those from right-sided CRC, indicating that left-sided CRC may have increased responsiveness to immunotherapy. Antibody-dependent cellular phagocytosis (ADCP) and antibody-dependent cellular cytotoxicity (ADCC) induced by M2-like macrophages were more pronounced in left-sided CRC and correlated with a good prognosis in CRC.

Background Gradually, more researches pay attention to the potential relationship between N6-methyladenosine (m6A) modification of RNA and immunity in tumor microenvironment (TME). Therefore, they developed unique scoring modes through detecting level of m6A in various tumors to learn immune phenotypes. Nevertheless, direct detection always is harmful even fatal to patients. Recent studies demonstrated that exosomes in body fluid would deliver RNA with m6A modification from tumors. Methods Through analyzing datasets from 1066 colon cancer samples, m6A-related exosome genes modification patterns which based on 59 m6A-related exosome genes was classified. Then we used MREGS to calculate modification patterns of each tumor with PCA algorithm. Results In accordance with 59 m6A-related exosome gene, we indicated that there were distinguishing characteristics of TME cell infiltration in three different m6A-related exosome gene modification patterns. Three immune cell infiltration profiles (immune-inflamed, immune-desert and immune-excluded) were pronouncedly relevant with the identified patterns in aspects of immune activation, EMT- and TGFβ-related pathways and activity of stroma in TME. We also discovered that tumor molecular subtypes, genetic aberrant expression and patients’ outcomes could be evaluated by identified modification patterns. Furthermore, patients in lower MREGS group, featured as prolonged lifespan and advantageous immune activation, was associated with high tumor mutation burden (TMB) and good prognosis with anti-PDL1 immune therapy. Conclusion Detecting the level of m6A methylation of exosomes in patients’ serum, MREGS could be utilized for assessing m6A-related exosome gene modification patterns of each patient and their own matching characteristics of TME cell infiltration, and next ascertain immunological classifications of tumors and assist clinicians to tailor optimal treatment for patients.

The formation of MgCO3·3H2O in the CO2 mineralization system was investigated using Mg(OH)2 as an intermediate at 20 °C. Liquid and solid analyses were done for qualitative and quantitative composition characterizations of the reacted samples. Results showed that the morphology of Mg(OH)2 had an obvious effect on the growth rate, size and morphology of MgCO3·3H2O. The formation of MgCO3·3H2O might be explained by the dissolution–recrystallization mechanism. Larger bundle-like MgCO3·3H2O which composed of middle-binding rod crystals was obtained from the plate-like Mg(OH)2. These findings could pave the way for controllable crystallization of MgCO3·3H2O in a CO2 mineralization system.

Background : Negative energy balance in cows will induce catabolism especially of lipids and the resulting rapid increase of free fatty acids (NEFA) in the blood stream increases the production of reactive oxygen metabolites (ROMs) and promote oxidative stress. Once the animal body is in an oxidative stress state, many molecules in the body may be peroxidized, accelerating the destruction of cells and causing damage to tissues or organs. This study conducted risk assessment of the oxidative stress caused by negative postpartum energy balance in cows by exploring the relationship between negative energy balance and oxidative stress. Materials, Methods & Results : This experiment randomly selected 120 cows at 14 to 21 days postpartum, from an intensive cattle farm in Heilongjiang province, China. Using a negative energy balance standard of β-hydroxybutyric acid (BHBA) greater than 1.2 mmol/L, nonesterified fatty acid (NEFA) greater than 0.4 mmol/L and glucose (GLU) less than three mmol/L, the cattle were divided into a healthy group of 74 cows and a diseased group of 46 cows. The oxidative stress indices of the experimental cows were measured and analyzed using the independent sample t test. Spearman correlation analysis and regression analysis were performed and by using the binary Logistic regression analysis to predict disease, the receiver-operating characteristic curve (ROC) analysis established diagnosis effect and boundary values. Compared with the healthy group, the levels of glutathione peroxidase (GSH-Px), catalase (CAT), vitamin E (VE), selenium (Se) and total nitric oxide synthetase (T-NOS) in the blood of dairy cows in the diseased group were significantly reduced and the level of malondialdehyde (MDA) was significantly increased. The study concluded that negative energy balance is associated with oxidative stress in cows and the blood levels of GSH-Px, CAT and Se can be used to evaluate the degree of resulting oxidative stress. The early warning levels were determined to be GSH-Px less than 619.28 U/L, CAT less than 7.87 U/ml and Se less than 0.51 μg/L. Discussion : The levels of GSH-Px, CAT, Se, T-NOS and VE in the blood of cows in the disease group were lower than those in the healthy control group. This may be due to the increase in energy demand of cows in the perinatal period and the decrease of DMI in this period, which promotes the NEB of cows. In order to alleviate the NEB, the body forces its metabolic enhancement. Some tissues of the body cannot adjust their metabolism to adapt to NEB and this leads to excessive NEFA, which causes oxidative stress. Excessive NEFA can also affect the expression of GSH-Px in cells, and causing a series of oxidation reactions, increased free radicals and as the antioxidant system is overwhelmed. The MDA content in the blood of the deficient group was significantly increased compared with the healthy group, positively correlated with NEFA and BHBA and negatively correlated with GLU. This may be due to severe oxidative stress in cows during the period of negative energy balance as MDA is one of the important products of membrane lipid peroxidation. Long chain PUFA are an important component of all cell membranes and their oxidation damages the integrity, fluidity and function of cell membranes. In summary MDA causes oxidative damage to cells, damages mitochondrial membranes and changes membrane permeability, resulting in more free radicals produced by mitochondria during biological oxidation.

The effect of ethanol on the crystallization and phase transformation of MgCO3·3H2O in a MgCl2–CO2–NH3·H2O system was investigated at 40 °C. The obtained crystals were characterized by X-ray diffraction and scanning electron microscopy, and the phase transformation behaviors of the MgCO3·3H2O crystals were studied quantitatively using an established thermal analysis method. The results showed that ethanol played a key role in inhibiting the aggregation of MgCO3·3H2O crystals because the adsorption of ethanol molecules on nuclei surfaces was preferential to that of water molecules. Active Mg2+ ions could be separated from the nuclei surfaces when 40% ethanol in solution, leading to the formation of more stable, flower-like crystals of 4MgCO3·Mg(OH)2·4H2O. The results of this study could contribute to the development of methods for controllable crystallization of MgCO3·3H2O.

We report on the synthesis and characterization of bent‐core liquid crystal (LC) compounds and the preparation of mixtures that provide an optically isotropic antiferroelectric (OI‐AFLC) liquid crystal display mode over a very wide temperature interval and well below room temperature. From the collection of compounds synthesized during this study, we recognized that several ternary mixtures displayed a modulated SmCaPA phase down to below −40 °C and up to about 100 °C on both heating and cooling, as well as optical tilt angles in the transformed state of approximately 45° (optically isotropic state). The materials were fully characterized and their liquid crystal as well as electro‐optical properties analyzed by polarized optical microscopy, differential scanning calorimetry, synchrotron X‐ray diffraction, dielectric spectroscopy, and electro‐optical tests.

Spatial confinement is known to affect molecular organizations of soft matter. We present an important manifestation of this statement for thin films of bent-core smectic liquid crystals. Prior freeze-fracture transmission electron microscopy (FFTEM) studies carried out on nitro-substituted bent-core mesogens ($n\text{\ensuremath{-}}\mathrm{OPIMB}\text{\ensuremath{-}}{\mathrm{NO}}_{2}$) revealed an undulated smectic layer structure with an undulation periodicity of $\ensuremath{\sim}8\text{ }\text{ }\mathrm{nm}$. We report cryogenic TEM measurements on $\ensuremath{\sim}100\text{ }\text{ }\mathrm{nm}$ thick $8\text{\ensuremath{-}}\mathrm{OPIMB}\text{\ensuremath{-}}{\mathrm{NO}}_{2}$ films. In contrast to FFTEM results, our studies show only density modulation with periodicity $b=16.2\text{ }\text{ }\mathrm{nm}$, and no smectic layer undulation. We show that the discrepancy between the FFTEM and cryogenic transmission electron microscopy (cryo-TEM) results can be attributed to the different sample thicknesses used in the experiments. FFTEM monitors cracked surfaces of a relatively thick ($5--10\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$) frozen sample, whereas cryo-TEM visualizes the volume of a thin ($0.1\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$) film that was quenched from its partially fluid phase. These results have importance in possible photovoltaics and organic electronics applications where submicron thin films are used.

We demonstrate the nanostructure and filament formation of a novel liquid crystal phase of a dimeric mesogen below the twist–bend nematic phase. The new fibre-forming phase is distinguished by a short-correlated smectic order combined with an additional nanoscale periodicity that is not associated with density modulation.

We present freeze-fracture transmission electron microscopy (FF-TEM), dielectric spectroscopy and electro-optic measurements on a dimeric liquid crystal mixture, which previously was proposed to form the twist-bend nematic (Ntb) phase. Our FF-TEM studies provide a direct image of a 10.5 nm periodic structure, consistent with the expected nanoscale, heliconical twist-bend modulation of the molecular orientation. Dielectric measurements in the 100 Hz to 10 MHz range reveal three nearly Debye-type dispersion processes in the nematic and the twist-bend phase. Low frequency 8 V/µm electric fields applied on planar cells cause the optical-scale stripe texture (another characteristic feature of the Ntb phase) to disappear. Higher (>16 V/µm) fields gradually realign the heliconical axis along the electric field; it relaxes back after the field removal.

Liquid crystals (LCs) represent a challenging group of materials for direct transmission electron microscopy (TEM) studies due to the complications in specimen preparation and the severe radiation damage. In this paper, we summarize a series of specimen preparation methods, including thin film and cryo-sectioning approaches, as a comprehensive toolset enabling high-resolution direct cryo-TEM observation of a broad range of LCs. We also present comparative analysis using cryo-TEM and replica freeze-fracture TEM on both thermotropic and lyotropic LCs. In addition to the revisits of previous practices, some new concepts are introduced, e.g., suspended thermotropic LC thin films, combined high-pressure freezing and cryo-sectioning of lyotropic LCs, and the complementary applications of direct TEM and indirect replica TEM techniques. The significance of subnanometer resolution cryo-TEM observation is demonstrated in a few important issues in LC studies, including providing direct evidences for the existence of nanoscale smectic domains in nematic bent-core thermotropic LCs, comprehensive understanding of the twist-bend nematic phase, and probing the packing of columnar aggregates in lyotropic chromonic LCs. Direct TEM observation opens ways to a variety of TEM techniques, suggesting that TEM (replica, cryo, and in situ techniques), in general, may be a promising part of the solution to the lack of effective structural probe at the molecular scale in LC studies.

We report results from a comprehensive suite of measurements, including small angle X-ray scattering (SAXS), polarising optical microscopy, dynamic light scattering, elastic properties and dielectric and diamagnetic susceptibilities on macroscopic liquid crystalline properties of branched compound, 2-(octyloxycarbonyl)-1, 4-phenylene bis(4-(octyloxy)benzoate). SAXS studies reveal very distinct, although short-range smectic-C-type clusters, leading to increased viscosities, very similar to that been reported in many bent-core compounds. The measured elastic constants and their relative values are similar to calamitic liquid crystals, presumably because the clusters are not polar, unlike in bent-core liquid crystals, which (together with the director tilt) result in a layer chirality.

Cryo-TEM studies on two smectic phases of an asymmetric bent-core liquid crystal material are presented and compared to prior X-ray results obtained in bulk samples. While the bulk samples have layer-modulated structures, those modulations are not observable in the 100-nm-thick TEM samples, indicating surface-induced suppression of the layer modulations. The observed layer spacing is in agreement with the X-ray results in the lower temperature smectic phase, but distinctly larger in the higher temperature phase. This indicates surface-induced suppression of the director tilt. Cryo-TEM textures resolve the profiles of individual smectic layers at the scales down to few nanometres and reveal the presence of edge and screw dislocations, twist grain boundaries, small-angle and large-angle tilt grain boundaries.

Topological defects determine many static and dynamic properties of liquid crystals. They are mainly studied by optical microscopy, which cannot reveal the detailed structure of the defect core, where the deformations are too strong to sustain the usual type of order. The size of the core in most of liquid crystals is in the range of 1-10 nanometers, which calls for imaging techniques with resolution much higher than the optical one. Here we summarize and discuss results of Transmission Electron Microscopy (TEM) nanoscale imaging of defects in several layered liquid crystals built of rod- and bent-shaped molecules. We will present and analyze structures of edge and screw dislocations, twist and tilt grain boundaries of smectic layers. Topological defects have large impact on optical properties of the LCs and understanding their nanoscale properties will help us structuring them for optical applications.

The synthesis and transition temperatures of the first series of 2-alkoxy-1,3-thiazole-based liquid crystals are reported. The 2-alkoxy-1,3-thiazole moiety was generated in high yield via a selective SNAr reaction between 2,5-dibromo-1,3-thiazole and the corresponding long-chain alkoxide. The synthesis and mesomorphic properties of the aforementioned chevron-free 2-alkoxy-1,3-thiazole-based liquid crystals are discussed and compared with their 5-alkoxy-1,3-thiazole and phenyl based analogues. Electrooptical properties for both series of alkoxy-1,3-thiazole-based liquid crystals are also presented and discussed.

We present chemical synthesis, polarising optical microscopy, electric current, and small-angle X-ray scattering measurements on a strongly anisotropic bent-shape liquid crystal material. We find that it has two layer-undulated ferroelectric phases, M1 and M2. In the higher temperature M2 phase the undulation amplitude and period increases on cooling, similar to other published materials. It can be identified with a tilted modulated phase. In the M1 phase the molecular plane is not tilted, and – in sharp contrast with all prior observations – the modulation amplitude and period decrease on cooling. These observations can be explained with a ‘leaning’ director structure, where the leaning angle is decreasing on cooling.

Sea cucumber is a nutritional aquatic food that is widely consumed in East Asian countries. Employing a rat model of ethanol-induced gastric ulcer, we examined the protective effect of sea cucumber fucoidan (SC-FUC) extracted from Acaudina molpadioides and explored the related mechanisms. Oral administration with 100 mg/kg body weight SC-FUC for 5 days can significantly prevent the formation of gastric ulcer. Moreover, SC-FUC pretreatment could alleviate ethanol-induced histological damage, reverse changes in tissue oxidation and antioxidase activities, and regulate the signalling pathways of mitogen-activated protein kinases and matrix metalloproteinases. This study investigated the ethanol-induced gastric ulcer protective effect of SC-FUC for the first time, and elucidated that the protective mechanisms included anti-oxidation, gastric matrix hydrolysis suppression, and anti-inflammation.

An encapsulated polymer stabilized cholesteric texture (EPSCT) light shutter is formed from a cholesteric liquid crystal and monomer that is encapsulated into micron sized, polymer-coated droplets by either an emulsification or phase separation process. The polymer-coated droplets are disposed between transparent electrodes, where they are irradiated by ultra-violet (UV) light to polymerize the monomer.

A series of liquid crystalline ligand-containing monomers with chemo-responsive properties has been prepared and studied. These molecules are functionalized derivatives of the 2,6-bisbenzimidazolylpyridine (Bip) ligand. Tailoring the size of the aromatic core and the length of two pairs of alkyl substituents allows the preparation of mesogens with a range of tunable thermal liquid crystalline transitions and phases. The binding of lanthanide- and/or transition metal salts to the ligand containing mesogens results in a transition from a liquid crystalline to an isotropic state. Acyclic diene metathesis of the monomers yielded either oligomers or polymers, dictated by whether the alkene is either terminal or nonterminal, respectively. Both oligomers and polymers exhibit enantiotropic liquid crystalline behavior and become isotropic in the presence of metal ions.

The Inside Cover picture highlights how an optically isotropic antiferroelectric liquid‐crystal display mode can be accomplished by using ternary bent‐core liquid crystal mixtures operating from well below room temperature up to 100 °C. More details can be found in the Communication by T. Hegmann and co‐workers on page 196 in Issue 2, 2017 (DOI: 10.1002/open.201600138).

This article has no abstract. Keywords: bent-core liquid crystals; ferroelectricity; nematic phase; smectic phase; Cotton–Mouton effect; Quincke rotation

Three series of bent-core mesogens having pyridine as the central unit have been synthesized and characterized. A series of 2,6-diaminopyridine derivatives capable of forming inter- and intramolecular hydrogen bonds exhibit very high melting points. A decrease in the polarity of the central part of the bent-core obtained by replacing the amide with ester linkages results in derivatives with lower melting points and formation of B2- and B7-like mesophases. The introduction of the olefinic groups, which connect the pyridine ring with the inner aromatic rings, helps to further lower the polarity of the central part in the five ring system and led to the formation of B1 and B7 phases. The phases have been determined by optical microscopy observations and differential scanning calorimetry (DSC) and confirmed by X-ray studies. The bending angles and polarity of the investigated five-ring systems have been calculated by the density functional theory (DFT) method. Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3668]

The B4 phase of bent-core liquid crystals has been shown to be an assembly of twisted layers stacked to form helical nanofilaments. Interestingly, some of them have structural colours that cannot be explained by the nanofilaments alone. Here cryogenic-transmission electron microscopy observations on 40-120 nm films of four bent-core liquid crystal materials show that the filaments are present even in contact with a carbon substrate with only minor deformation, thus representing bulk properties. We find that the subsequent arrays of nanofilaments are not parallel to each other, but rotate by an angle of 35-40° with respect to each other. This doubly twisted structure can explain the structural colour. Being principally different from the packing of molecules in the twist grain boundary and blue phases, the double-twist structure of helical nanofilaments expands the rich word of nanostructured organic materials.

The synthesis and small-angle X-ray scattering (SAXS) characterization is reported for 20 laterally branched mesogenic molecules, which are derived from the common rod-shaped 2,5-bis([4-(octyloxy)phenyl]carbonyloxy) benzoic acid unit. These compounds have a varying degree of flexibility, in that their lateral branch is formed upon conversion of the acid to either an ester or an amide, and most laterally branched molecules exhibit relatively wide nematic liquid-crystal phases with a direct nematic-to-crystal transition at lower temperatures. SAXS studies reveal the presence of smectic-like nanostructures (clusters) with short-range order in the nematic phase, with characteristic correlation lengths from 3 to over 10 nm. The smectic layers that are contained in these clusters are tilted with respect to the nematic director by angles ranging from 0° (i.e. untilted) to 55°. In some compounds, the intensity of the SAXS peak corresponding to the smectic layer spacing depends strongly on temperature. The main features of the nanostructures can be understood based on the molecular structure; therefore, guiding future synthetic work towards more precisely controlled and technologically useful nanostructures in nematics.

Structure of fucoidan from sea cucumber Acaudina molpadioides (Am-FUC) was investigated in this study. Low molecular weight polysaccharide of Am-FUC (Am-LMW) was prepared by enzymatic degradation and assayed by nuclear magnetic resonance. According to the structure of Am-LMW, and referring to previously reported information of Am-FUC oligosaccharides, the structure of Am-FUC was elucidated as [-> 3-alpha-L-Fucp-1 -> 3-alpha-L-Fucp2,4(OSO3-)-1 -> 3-alpha-L-Fucp-1 -> 3-alpha-L-Fucp2(OSO3-)-1 ->](n). Compared to other investigated fucoidans, which also consist of tetrafucose repeating units with 1 3-linkages, Am-FUC contains a novel repeating unit distinctive in sulphation pattern. (C) 2013 Elsevier Ltd. All rights reserved.

Sea cucumber fucoidan is a major bioactive component of sea cucumber. Sea cucumber is widely consumed in East Asian countries as healthy food. Employing the degrading enzyme from the marine bacterium strain Flavobacteriaceae CZ1127, sea cucumber (Acaudina molpadioides) fucoidan oligosaccharides were prepared by enzymatic hydrolysis. The oligosaccharide profile of the hydrolysate was determined by liquid chromatography coupled with mass spectrometry (LC–MS). With the assistance of LC–MS, four major oligosaccharides in the hydrolysate were purified. By using tandem mass spectrometry and nuclear magnetic resonance, delicate structures of the oligosaccharides were verified as α- l -Fuc p -1 → 3-α- l -Fuc p (2,4O SO 3 2 - )-1 → 3-α- l -Fuc p , α- l -Fuc p -1 → 3-α- l -Fuc p (2,4O SO 3 2 - )-1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p , α- l -Fuc p -1 → 3-α- l -Fuc p (2,4O SO 3 2 - )-1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p (2,4O SO 3 2 - )-1 → 3-α- l -Fuc p and α- l -Fuc p -1 → 3-α- l -Fuc p (2,4O SO 3 2 - )-1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p (2,4O SO 3 2 - )-1 → 3-α- l -Fuc p -1 → 3-α- l -Fuc p .

We demonstrate subnanometer resolution cryo-TEM imaging of smectic layers in the smectic and nematic phases of two bent-core liquid crystals. Our results show perfect periodicity over several hundred layers in the smectic phase and also provide the first direct evidence of smectic clusters on length scales of 30--50 nm in a nematic liquid crystal. The results are corroborated with small angle x-ray scattering measurements. The observation of smectic clusters in the nematic phase is of special interest in bent-core liquid crystals, where the smectic clusters are stable over wide temperature ranges, in contrast to the well-known pretransitional ``cybotactic'' clusters that appear only in the vicinity of a bulk smectic phase. The means to characterize and manipulate this nanoscale molecular order could open up completely new liquid crystal-based technologies.

Antarctic krill (Euphausia superba) has been widely studied and extensively recognized as a target for commercial fishing. In this study, Antarctic krill chitin was extracted from defatted Antarctic krill shell, and its crystalline structure and thermal properties were characterized by employing Fourier transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy, thermogravimetry, and differential scanning calorimetry. Results showed that Antarctic krill chitin corresponded to the α-polymorph, and was composed of small, stable, and uniform microcrystals. The degree of N-deacetylation was 11.28 ± 0.86%. The d-spacings of Antarctic krill chitin were 9.78 A and 4.63 A at (020) and (110) planes. The crystalline sizes were 6.07 nm and 5.16 nm at (020) and (110) planes, respectively. The activation energy of the polysaccharide chain decomposition was 123.35 kJ/mol and the glass transition (T(g)) of Antarctic krill chitin was 164.96 °C.

We report on a series of measurements on the microscopic structure and the magneto-optical properties of a calamitic liquid crystalline compound in its nematic phase. Structural studies show the existence of short-range, tilted smectic order consistent with pretransitional effects above an underlying smectic phase. Concomitantly, magneto-optical results exhibit the existence of an optic axis not collinear with the uniaxial director. This apparent biaxial nature is discussed within the context of coupling between the tensor nematic and the smectic order parameters.

The convergence of the growing need for spatial data management with the emergence of XML as a data exchange standard has made XML-based solutions the preferred choice for most modern GIS applications. However, benchmarks for XML-GIS systems and applications do not yet exist. In this paper, we propose GeOO7, a relevant, portable, scalable and simple benchmark for XML-GIS management systems. The dataset of the benchmark follows the schema and characteristics of a real and publicly available dataset. The workload emulates a representative set of GIS spatial operations. Our analysis shows that the GeOO7 benchmark conforms well to benchmark specification criteria

Liquid crystals (LCs) represent a challenging group of materials for direct transmission electron microscopy (TEM) studies due to the complications in specimen preparation and the severe radiation damage. In this paper, we summarize a series of specimen preparation methods, including thin film and cryo-sectioning approaches, as a comprehensive toolset enabling high-resolution direct cryo-TEM observation of a broad range of LCs. We also present comparative analysis using cryo-TEM and replica freeze-fracture TEM on both thermotropic and lyotropic LCs. In addition to the revisits of previous practices, some new concepts are introduced, e.g., suspended thermotropic LC thin films, combined high-pressure freezing and cryo-sectioning of lyotropic LCs, and the complementary applications of direct TEM and indirect replica TEM techniques. The significance of subnanometer resolution cryo-TEM observation is demonstrated in a few important issues in LC studies, including providing direct evidences for the existence of nanoscale smectic domains in nematic bent-core thermotropic LCs, comprehensive understanding of the twist-bend nematic phase, and probing the packing of columnar aggregates in lyotropic chromonic LCs. Direct TEM observation opens ways to a variety of TEM techniques, suggesting that TEM (replica, cryo, and in situ techniques), in general, may be a promising part of the solution to the lack of effective structural probe at the molecular scale in LC studies. Microsc. Res. Tech. 77:754-772, 2014. © 2014 Wiley Periodicals, Inc.

Three-ring bent-core bis(4-subst.-phenyl) 2-methyl-iso-phthalates exhibiting nematic, SmA and SmC phases are reported. The occurring mesophases have been identified by their optical textures and X-ray diffraction measurements which give also geometrical structural parameters like layer spacing and molecular tilt. Quantum chemical calculations on single molecules and X-ray structure analysis in the crystalline state indicate wide opening angles (about 155°) of the molecular legs due to the lateral methyl group in position 2 of the central phenyl ring. However solid state NMR spectroscopy in the liquid crystalline phases finds stronger molecular bending (bending angle to be about 138° in the SmA and about 146° in the nematic phase). Dielectric and SHG measurements give evidence that in the SmA phase a polar structure can be induced by application of an electric field which disappears in the isotropic liquid phase. The electric field not only leads to a slight textural change even in the SmA phase but also polar-type electric current response (PS about 200 nC cm−2) is observed. This unusual electro-optical behaviour is discussed on the basis of the orientation of polar clusters formed by the bent molecules. In the paper we not only attempt to characterize the mesophases and to describe their physical properties, but we also show that these types of molecules represent the borderline between bent-shaped and calamitic liquid crystals.