Stimulated transformation of soft helix among helicoidal, heliconical, and their inverse helices.

Dynamic modulation of soft helix in terms of the molecular organization, handedness, and pitch length could result in a sophisticated control over its functions, opening numerous possibilities toward the exploration of previously unidentified applications. Here, we report a dynamic and reversible transformation of a soft helical superstructure among the helicoidal (molecules orthogonal to helical axis), heliconical (molecules oblique to the helical axis, i.e., oblique helicoidal), and their inverse helices, together with a tunability on the helical pitch, by combining electrical and optical manipulations. This multistate transformation depends on a matching of the temperature, the strength of external stimuli, and the bend and twist elastic effects of the system. A laser emission with tunable wavelength and polarization, and prescribed micropatterns formed by any aforementioned architectures were achieved.

[Current situations and problem analysis of influencing factors of traditional Chinese medicine tablets on forming quality].

The compressibility of tablets is the essential operating unit during the preparation of traditional Chinese medicine tablets, as well as a complicated process. Therefore, it is of great significance to comprehensively study the influencing factors on the formation process. This paper aimed to review the evaluation methods for the tablet forming quality and highlight the effects of material powder properties, excipients and preparation technology on the quality of traditional Chinese medicine tablets on the basis of relevant literatures. Furthermore, the common problems in tablet forming process are also analyzed to provide useful references for the development of tablet forming quality of traditional Chinese medicines.

Artificial web of disclination lines in nematic liquid crystals.

Disclinations are topological singularities of molecular arrangement in liquid crystals, which typically occur when the average orientation of molecules makes a π rotation along a fictitious closed loop taken inside the liquid crystal. Depending on the sense of molecular rotation, the disclination lines are either of 1/2 or -1/2 strength. When two disclination lines with the opposite strength meet, they are annihilated without trace. It is hence generally considered difficult in the nematic phase to stabilize a condensed array of free-standing disclination lines without the aid of topological objects like colloidal inclusions. Here we show that a free-standing web of 1/2-strength twist disclination lines can be stably formed in thin liquid crystal cells by means of a judicious combination of orientationally patterned confining surfaces fabricated by the micropatterned photoalignment technique. Theoretical model indicates that disclination lines are held apart at the intersection by a repulsive force generated by the Frank elasticity.Disclination lines are topological defects in molecular orientation widely found in liquid crystals. Here Wang et al. use a surface patterning technique to produce a very stable freestanding 3D array of ½ twist disclinations, which could be exploited in a variety of nanometre scale applications.

Light-Patterned Crystallographic Direction of a Self-Organized 3D Soft Photonic Crystal.

Uniform and patterned orientation of a crystallographic direction of ordered materials is of fundamental significance and of great interest for electronic and photonic applications. However, such orientation control is generally complicated and challenging with regard to inorganic and organic crystalline materials due to the occurrence of uncontrollable dislocations or defects. Achieving uniform lattice orientation in frustrated liquid-crystalline phases, like cubic blue phases, is a formidable task. Taming and tailoring the ordering of such soft, cubic lattices along predetermined or desired directions, and even imparting a prescribed pattern on lattice orientation, are more challenging, due to the entropy-domination attribute of soft matter. Herein, we disclose a facile way to realize designed micropatterning of a crystallographic direction of a soft, cubic liquid-crystal superstructure, exhibiting an alternate uniform and random orientation of the lattice crystallographic direction enabled by a photoalignment technique. Because of the rewritable trait of the photoalignment film, the pattern can be erased and rewritten on-demand by light. Such an oriented soft lattice sensitively responds to various external stimuli such as temperature, electric field, and light irradiation. Furthermore, advanced reflective photonic applications are achieved based on the patterned crystallographic orientation of the cubic blue phase, soft lattice.

Controllable Dynamic Zigzag Pattern Formation in a Soft Helical Superstructure.

Zigzag pattern formation is a common and important phenomenon in nature serving a multitude of purposes. For example, the zigzag-shaped edge of green leaves boosts the transportation and absorption of nutrients. However, the elucidation of this complicated shape formation is challenging in fluid mechanics and soft condensed matter systems. Herein, a dynamically reconfigurable zigzag pattern deformation of a soft helical superstructure is demonstrated in a photoresponsive self-organized cholesteric liquid crystal superstructure under the simultaneous influence of an applied electric field and light irradiation. The zigzag-shaped pattern can not only be generated and terminated repeatedly on demand, but can also be easily manipulated by alternating irradiation of ultraviolet and visible light while under the influence of a sustained electric field. This unique behavior results from a delicate balance among the variable experimental parameters. The evolution of the zigzag-shaped pattern is successfully modeled by numerical simulations and has been monitored through diffraction of a probe laser. Interestingly, this fascinating zigzag-shaped pattern yields crescent-shaped diffraction pattern. The reversibly controllable dynamic zigzag pattern could enable the fabrication of novel photonic devices and architectures, besides greatly advancing the fundamental understanding of temporal behavior of ordered soft materials under combined stimuli.

Identification of an NDM-5-producing Escherichia coli Sequence Type 167 in a Neonatal Patient in China.

Emergence of New Delhi metallo-ß-lactamase-producing Enterobacteriaceae has become a challenging threat to public health. Two carbapenem-resistant Escherichia coli, strain QD28 and QD29, were recovered from the aspirating sputum of a neonate and the urine of an adult in a Chinese hospital in 2013. Molecular typing revealed that both isolates belonged to the sequence type 167, but they were clonally diverse. Both isolates exhibited resistance to carbapenems, cephalosporins, ciprofloxacin, gentamicin, piperacillin-tazobactam and trimethoprim-sulfamethoxazole. In addition, strain QD28 was also resistant to aztreonam, and strain QD29 was resistant to amikacin, fosfomycin and minocycline. Antimicrobial resistance gene screening revealed that strain QD28 harbored aac(6')-Ib, blaCTX-M-14, blaNDM-5, blaTEM-1 and sul1 genes, and strain QD29 harbored aac(6')-Ib, blaCTX-M-3, blaNDM-5, blaTEM-1, rmtB, sul1 and sul2 genes. The blaNDM-5 gene was found to be located on a 46-kb plasmid in two isolates, and further sequence analysis showed that this plasmid was highly similar to the previously reported IncX3 plasmid pNDM-MGR194 in India. This is the first identification of blaNDM-5-carrying E. coli in the neonatal infection.

Three-dimensional control of the helical axis of a chiral nematic liquid crystal by light.

Chiral nematic liquid crystals--otherwise referred to as cholesteric liquid crystals (CLCs)--are self-organized helical superstructures that find practical application in, for example, thermography, reflective displays, tuneable colour filters and mirrorless lasing. Dynamic, remote and three-dimensional control over the helical axis of CLCs is desirable, but challenging. For example, the orientation of the helical axis relative to the substrate can be changed from perpendicular to parallel by applying an alternating-current electric field, by changing the anchoring conditions of the substrate, or by altering the topography of the substrate's surface; separately, in-plane rotation of the helical axis parallel to the substrate can be driven by a direct-current field. Here we report three-dimensional manipulation of the helical axis of a CLC, together with inversion of its handedness, achieved solely with a light stimulus. We use this technique to carry out light-activated, wide-area, reversible two-dimensional beam steering--previously accomplished using complex integrated systems and optical phased arrays. During the three-dimensional manipulation by light, the helical axis undergoes, in sequence, a reversible transition from perpendicular to parallel, followed by in-plane rotation on the substrate surface. Such reversible manipulation depends on experimental parameters such as cell thickness, surface anchoring condition, and pitch length. Because there is no thermal relaxation, the system can be driven either forwards or backwards from any light-activated intermediate state. We also describe reversible photocontrol between a two-dimensional diffraction state, a one-dimensional diffraction state and a diffraction 'off' state in a bilayer cell.

Electrically tunable selective reflection of light from ultraviolet to visible and infrared by heliconical cholesterics.

Electrical tuning of selective reflection of light is achieved in a very broad spectral range from ultraviolet to visible and infrared by an oblique helicoidal state of a cholesteric liquid crystal in a wide temperature range (including room temperature). The phenomenon offers potential applications in tunable smart windows, lasers, optical filters and limiters, as well as in displays.

Coexistence of SFO-1 and NDM-1 ß-lactamase genes and fosfomycin resistance gene fosA3 in an Escherichia coli clinical isolate.

This study aims to characterize antimicrobial resistance and antimicrobial resistance genetic determinants of an Escherichia coli clinical isolate HD0149 from China in 2012. This strain displayed high-level resistance to cephalosporins, carbapenems, fluoroquinolones, aminoglycosides and fosfomycin. A range of antimicrobial resistance genes was detected responsible for its multiple antimicrobial resistances, involving the blaCMY-2, blaCTX-M-65, blaNDM-1, blaSFO-1, blaTEM-1, fosA3, rmtB, sul1 and sul2 genes. Four amino acid substitutions were detected in the quinolone resistance-determining regions (QRDRs) of GyrA (S83L and D87N), ParC (S80I) and ParE (S458A). Conjugation experiments revealed two multiresistance plasmids present in E. coli HD0149. The blaSFO-1 gene associated with blaNDM-1 gene was located in a 190 kb IncA/C plasmid and the blaCTX-M-65, fosA3 and rmtB genes were located in a 110 kb IncF plasmid. This is the first identification of the blaSFO-1 gene in an E. coli isolate and on a conjugative IncA/C plasmid. This may dramatically enhance the international prevalence and dissemination of blaSFO-1 among Enterobacteriaceae.

Luminescence-driven reversible handedness inversion of self-organized helical superstructures enabled by a novel near-infrared light nanotransducer.

Nanotransducer-impregnated self-organized helical superstructures are found to exhibit unprecedented reversible handedness inversion upon irradiation by the dual-wavelength near-infrared light. Upon near-infrared laser irradiation at 808 nm, the helical twist sense changes from right-handed to left-handed through an achiral liquid-crystal phase, whereas its reverse process occurs upon the near-infrared laser irradiation at 980 nm.

Inhibition of vascular endothelial growth factor by small interfering RNA upregulates differentiation, maturation and function of dendritic cells.

This study aimed to investigate the effects of vascular endothelial growth factor (VEGF) secreted by MCF-7 breast cancer cells on the differentiation, maturation and function of dendritic cells (DCs). Small interfering RNAs (siRNAs) directed against the VEGF gene were designed and transfected into MCF-7 breast cancer cells at an optimal concentration (100 nmol/l) using cationic liposome transfection reagent, whereas the control group was transfected with only transfection reagent. Western blot analysis and ELISA were used to determine VEGF protein expression and VEGF concentration, respectively. Mononuclear cells were cultured with the culture supernatants from primary MCF-7 cells (control group) and siRNA-treated MCF-7 cells (siRNA group). The DC phenotypes, including CD1a, CD80, CD83, CD86 and HLA-DR, were evaluated by flow cytometry. The MTT assay was used to assess the cytotoxicity of DC-mediated tumor-specific cytotoxic T lymphocytes (CTLs) against MCF-7 cells in the two different culture supernatants. The VEGF-targeted constructed siRNA inhibited VEGF expression in MCF-7 cells. Cultivation with the culture supernatants from MCF-7 cells treated with siRNA affected DC morphology. DCs in the siRNA group exhibited a significantly higher expression of CD86, CD80, CD83 and HLA-DR compared to the cells in the control group, whereas the expression of CD1a in the siRNA group was significantly lower compared to that in the control group. The cytotoxic activity of CTLs mediated by DCs was significantly altered by siRNA transfection. These results indicated that VEGF may play a significant role in tumor development, progression and immunosuppression.

Light-directing omnidirectional circularly polarized reflection from liquid-crystal droplets.

Constructing and tuning self-organized three-dimensional (3D) superstructures with tailored functionality is crucial in the nanofabrication of smart molecular devices. Herein we fabricate a self-organized, phototunable 3D photonic superstructure from monodisperse droplets of one-dimensional cholesteric liquid crystal (CLC) containing a photosensitive chiral molecular switch with high helical twisting power. The droplets are obtained by a glass capillary microfluidic technique by dispersing into PVA solution that facilitates planar anchoring of the liquid-crystal molecules at the droplet surface, as confirmed by the observation of normal incidence selective circular polarized reflection in all directions from the core of individual droplet. Photoirradiation of the droplets furnishes dynamic reflection colors without thermal relaxation, whose wavelength can be tuned reversibly by variation of the irradiation time. The results provided clear evidence on the phototunable reflection in all directions.

Rationally designed axially chiral diarylethene switches with high helical twisting power.

Three rationally designed axially chiral diarylethene switches were synthesized and their application as chiral dopants for phototunable cholesteric liquid crystal devices was investigated. Design of these molecules was based on the combination of photochromic dithienylcyclopentene core with bridged binaphthyl units as chiral precursors. Aromatic groups were introduced to the molecules at 6,6'-positions of binaphthyls through a Suzuki-Miyaura coupling reaction. Their helical twisting powers (HTPs) are significantly higher than those of the known chiral diarylethenes reported as chiral dopants so far. Photocyclization of these molecules upon light irradiation brought out dramatic variation in HTPs between different states. The primary colors, red, green, and blue, were obtained in reflection on light irradiation and with thermal stability. Moreover, a multi-switchable photodisplay was demonstrated using one of these chiral molecular switches.

Reversible near-infrared light directed reflection in a self-organized helical superstructure loaded with upconversion nanoparticles.

Adding external, dynamic control to self-organized superstructures with desired functionalities is an important leap necessary in leveraging the fascinating molecular systems for applications. Here, the new light-driven chiral molecular switch and upconversion nanoparticles, doped in a liquid crystal media, were able to self-organize into an optically tunable helical superstructure. The resulting nanoparticle impregnated helical superstructure was found to exhibit unprecedented reversible near-infrared (NIR) light-guided tunable behavior only by modulating the excitation power density of a continuous-wave NIR laser (980 nm). Upon irradiation by the NIR laser at the high power density, the reflection wavelength of the photonic superstructure red-shifted, whereas its reverse process occurred upon irradiation by the same laser but with the lower power density. Furthermore, reversible dynamic NIR-light-driven red, green, and blue reflections in a single thin film, achieved only by varying the power density of the NIR light, were for the first time demonstrated.

Photodynamic chiral molecular switches with thermal stability: from reflection wavelength tuning to handedness inversion of self-organized helical superstructures.

A good turn: Three compounds that bear two axially chiral bridged binaphthyl units were developed as photodynamic chiral dopants for nematic liquid crystals. For compounds with suitable bridge lengths, a change in the dihedral angle induced a switch of the binaphthyl units from the cisoid to the transoid form upon UV irradiation, which led to an inversion of the handedness of the helices.

Red, green and blue reflections enabled in an optically tunable self-organized 3D cubic nanostructured thin film.

A new light-driven chiral molecular switch doped in a stable blue phase (BP) liquid crystal allows wide optical tunability of three-dimensional cubic nanostructures with a selective reflection wavelength that is reversibly tuned through the visible region. Moreover, unprecedented reversible light-directed red, green, and blue reflections of the self-organized three-dimensional cubic nanostructure in a single film are demonstrated for the first time. Additionally, unusual isothermal photo-stimulated less ordered BP II to more ordered BP I phase transition was observed in the system.

Porphyrin metal complex monolayer-protected gold nanorods: a parallel facile synthesis and self-assembly.

Porphyrin metal (Zn, Cu, and Mg) complex monolayer-protected gold nanorods (GNRs) were, for the first time, synthesized. Their synthesis was easy to access by mixing porphyrin encapsulated GNRs with corresponding excess soluble metal salts in solution, followed by the facile purification through centrifugation and sonication due to the gravity of the GNRs and their solubility in organic solvents. Furthermore, the resulting three GNRs exhibited distinct spectroscopic properties and were able to self-assemble into side-by-side arrays driven by π-π intermolecular interactions of the surface metal porphyrin chromophores.

Photochemically reversible and thermally stable axially chiral diarylethene switches.

A series of dithienylcyclopentenes containing axially chiral 1,1'-binaphthyl units were successfully synthesized by a Suzuki-Miyaura protocol. All these compounds exhibited photochemically reversible isomerization with thermal stability in both organic solvent and a liquid crystal (LC) host. When doping into an achiral LC host, some of them exhibited very high helical twisting powers. Reversible reflection wavelength tuning in the visible region and LC phase switching between nematic and cholesteric upon light irradiation were demonstrated.

Reversible light-directed red, green, and blue reflection with thermal stability enabled by a self-organized helical superstructure.

Adding external, remote, and dynamic control to self-organized superstructures with desired properties is an important leap necessary in leveraging the fascinating molecular subsystems for employment in applications. Here two novel light-driven dithienylethene chiral molecular switches possessing remarkable changes in helical twisting power during photoisomerization as well as very high helical twisting powers were found to experience photochemically reversible isomerization with thermal stability in both isotropic organic solvents and anisotropic liquid crystal media. When doped into a commercially available achiral liquid crystal host, the chiral switch was able to either immediately induce an optically tunable helical superstructure or retain an achiral photoresponsive liquid crystal phase whose helical superstructure was induced and tuned reversibly upon light irradiation. Moreover, reversible light-directed red, green, and blue reflection colors with thermal stability in a single thin film were demonstrated.