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It is a great challenge to detect hydrofluoric acid (HF) with high precision, good selectivity, and visual readouts characteristics. Herein, a new photonic crystal (PC) hydrogel HF sensor based on the "selective etching-induced swelling" mechanism has been developed. This HF sensor consisting of silica/water/hydroxyethyl acrylate and non-closely packed structures was fabricated through simple non-close-assembling, photopolymerization, and water swelling processes. Silica slightly etched by HF induces the swelling of PC hydrogel, leading to the variation of reflection wavelength and structural colors, thereby realizing visually and spectrally sensing HF (0-10 mM). The unique structure and compositions of PC hydrogel are the keys to the high sensing precision, outstanding selectivity, and low detection limit (0.1 mM). Furthermore, the sensor possesses tailorable, portable, easy-to-operation, and low-cost (0.01 $/sensor) advantages. This work provides an efficient and convenient tool for sensing and recognizing HF in the aqueous solution for practical applications and upgrades the basic understanding of the photonic sensing mechanism.

The skins of chameleons have attracted growing interest because they have sensitive mechano-chromic properties and bright colors due to the large surface-to-surface distances (

Photonic crystal (PC) patterns have shown wide applications in optical devices, information encryption, anticounterfeiting, etc. Unfortunately, it is still a great challenge to reconfigure the PC patterns once fabricated. Herein, a new strategy is presented to reconfigure self-recordable PC patterns by printing local patterns into the chameleon-inspired PC papers using the phase change material (PCM) as ink and then erasing the patterns in ethanol. Multicolor and high-resolution (25 and 75 μ m for dot and lines, respectively) patterns can be efficiently and repeatedly reconfigured. In addition, the photonic patterns based on the PC paper and PCM combinations are gifted with mechanochromic characteristics and can show programmable and reversible color change under pressure. The high melting point of the ink, nonclosely packed structures of the PC paper, and the similar solubility parameter of PC paper, PCM, and ethanol are the keys for all these characteristics. This work offers a simple, flexible, efficient way to reconfigure PC patterns with mechanochromic properties and could open up exciting applications for novel hand-operation-based anticounterfeiting and optical devices.

Artificial photo-driven water oxidation has been proposed over half a century through a four-charge involved multiple-step oxygen evolution process. However, the knowledge of the intrinsic activity, such as the rate-law of the water oxidation reactions, has been inadequately studied. Up to date, the highest order reported is the third one under photoelectrochemical condition. In this work, we identified the fourth-order charge decay reactions on hematite by using a time-resolved surface photovoltage probe technique. A theoretical turnover frequency (TOF) > 100 nm(−2)·s(−1) can be expected for O(2) molecules when the hole density >0.1 nm(−2). This work demonstrates a facile and robust method to investigate the high-order reaction kinetics. More excitingly, this research built the bridge between the rate-law, rate-determining step, and energy barrier of intermediates.

Owing to the diversity of consumer’s demand, the traditional Sichuan brocade products have to be innovated in order to survive in a competitive environment. Since the construction of traditional Sichuan brocade was composed of basic-weave, the surface of the fabric shows a regular interweaving planar texture and is difficult to represent a three-dimensional effect. Inspired by embroidery handcraft, this paper attempts to achieve the embroidery-like effect on the fabric through the jacquard process. Based on the multi-backed structure of traditional Sichuan brocade, we adopted the zoned-combination design mode and added extra free-floats interlacing weave in the area where we want to show the embroidered effect and arranged the interlacing points by referring to the feature of the pattern. As a result, designed Sichuan brocades by this method are capable of displaying embroidered effect with high realism and three-dimensionality. This approach improves the artistic effect of the traditional Sichuan brocade and provides a technical reference for further texture design of jacquard fabrics.

Photonic crystals (PCs) with controllable lattice structures, photonic bandgaps, and brilliant colors are fabricated by the self‐assembly of the monodispersed anisotropic metal–organic framework (MOF) ZIF‐8 particles into long‐range ordered superstructures. The shape parameter (m) of the particles is used to quantify to what degree the particle shape has deformed from that of a perfect sphere (m = 2) and that of a perfect cube (m = ∞). It is experimentally proven that m value is the key for controlling the lattice structures. Three PCs with different m values of ZIF‐8 particles (9.7, 4.7, and 2.5) are found to be simple cubic, rhombohedral, and face‐centered‐cubic structures, respectively. Different from the conventional spherical particles‐based PCs, brilliant colors can be generated from the second‐order diffraction of the nonspherical MOFs‐based PCs. Taking advantage of this unique characteristic, a new information encryption technology is developed by combing the first‐order diffraction of rhombohedral PCs and first‐second‐order diffraction of simple‐cubic PCs. This work paves a way to explore nonspherical particle‐based PCs materials with different crystal forms and provides a new insight in novel optical characteristics of the PCs, which will promote their applications in anticounterfeiting, color displays, and printings.

Summary: Artificial photo-driven water oxidation has been proposed over half a century through a four-charge involved multiple-step oxygen evolution process. However, the knowledge of the intrinsic activity, such as the rate-law of the water oxidation reactions, has been inadequately studied. Up to date, the highest order reported is the third one under photoelectrochemical condition. In this work, we identified the fourth-order charge decay reactions on hematite by using a time-resolved surface photovoltage probe technique. A theoretical turnover frequency (TOF) > 100 nm−2·s−1 can be expected for O2 molecules when the hole density >0.1 nm−2. This work demonstrates a facile and robust method to investigate the high-order reaction kinetics. More excitingly, this research built the bridge between the rate-law, rate-determining step, and energy barrier of intermediates.

Rationally designing heterostructure is a promising way to promote the charge carrier separation of intrinsic photocatalysts, thus contributes the improvement of solar to chemical energy conversion. Herein, a novel isotype heterojunction consisted of MCN and UCN, respectively derived from hydrothermally-treated melamine and urea, was synthesized. Owing to the well compatibility and matched band structure, an S-scheme charge transfer mechanism is confirmed for working on MCN/UCN isotype heterojunction, thus endowing strong redox ability, efficient charge carrier separation efficiency and prolonged lifetime. As a result, MCN/UCN exhibits improved photocatalytic water splitting activity under visible light irradiation, which displays approximately 5.5 and 1.8-fold enhancement as compared to the pure MCN and UCN, respectively. The rationally synthesized S-scheme isotype heterojunction will pave the way for developing highly efficient g-C3N4-based photocatalysts.

Titanium carbide (TiC) was prepared via one simple route by the reaction of metallic magnesium powders with titanium dioxide (TiO 2 ) and potassium acetate (CH 3 COOK) in an autoclave at 600 °C and 8 h. Phase structure and morphology were characterized by X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). The results indicated that the product was cubic TiC, which consisted of particles with an average size of about 100 nm in diameter. The product was also studied by the thermogravimetric analysis (TGA) and its photocatalysis. It had good thermal stability and oxidation resistance below 350 °C in air. In addition, we discovered that the cubic TiC powders exhibited photocatalytic activity in degradation of Rhodamine-B (RhB) under 500 W mercury lamp light irradiation.

Chain Fe 3 O 4 nanoparticles encapsulated in worm-shaped carbon shell (defined as “WCCIOs”) were in situ synthesized by copyrolysis of polyethylene, malated-polypropylene and ferrocene in the presence of 10 ml H 2 O in an autoclave at 700 ∘ C for 12 h. The shell thicknesses of these WCCIOs are about 180 nm and the lengths reach up to several micrometers. And the average size of the Fe 3 O 4 nanoparticles inside the worm-shaped carbon shell is about 100 nm. The shapes and compositions of WCCIOs were simply controlled by adjusting the reaction temperatures and relative amounts of the precursors. On the basis of the experimental results, the formation process of the WCCIOs is discussed. The WCCIOs possess well acid resistance, which differs from those reported previously: the nanoparticles were embedded inside the thicker carbon shell. It is also found that the coercivity ( Hc ) value of the WCCIOs is much higher than that of bare Fe 3 O 4 nanoparticles and bulk Fe 3 O 4 .

In this study, nanoparticles-assembled Ag 2 S nanorods and nanotubes were synthesized via a one-step surfactant-assisted solvothermal route. The as-synthesized products have been characterized by powder X-ray diffraction and electron microscopy. A series of control experiments were carried out in order to survey the formation and morphological evolution process of Ag 2 S nanorods and nanotubes. The results showed that the final Ag 2 S nanorods and nanotubes originated from the precursor AgSCN. The default experiment showed that potassium oleate played important roles in controlling the morphologies of the initial precursor AgSCN as soft template and those of the resultant Ag 2 S as bonding agent. PL spectrum of as-synthesized Ag 2 S nanotubes displays two emission peaks centered at 418 and 436 nm under excitation wavelength of 365 nm at room temperature. This differs from previous reports and may be attributed to this kind of nanoparticles-assembled one-dimensional (1-D) nanostructures.

Hexagonal V0.13Mo0.87O2.935 nanowires were hydrothermally synthesized at 220 °C for the first time. X-ray diffraction and field-emission scanning electron microscopy were utilized to characterize the phase and morphology of the nanowires, respectively. Transmission electron microscopy and selected area electron diffraction indicate that the nanowires are single crystalline, growing along the [001] direction. Interestingly, the nanowires easily become amorphous under the electron irradiation. The comparative hydrothermal experiments show that the molar ratio between the starting reagents of Mo and NH4VO3 plays a vital role in the anisotropic growth of nanowires. The photoluminescence measurement demonstrates that these nanowires exhibit two strong emission peaks at 420 and 438 nm, which are probably related to the intrinsic oxygen vacancies.

Single-crystal trigonal (t) Se nanobelts have been synthesized on a large scale by reducing SeO2 with glucose at 160 °C. Electron microscopy images show that the nanobelts are ∼80 nm in diameter, ∼25 nm in thickness, and up to several hundreds of micrometers in length. HRTEM images prove that the nanobelts are single crystals and preferentially grow along the [001] direction. The time-dependent TEM images revealed that the formation and growth of t-Se nanobelts were governed by a solid−solution−solid growth mechanism. The redox reaction directly produced amorphous (α) Se nanoparticles under hydrothermal conditions. t-Se nanobelts were formed by dissolution and recrystallization of the initial α-Se nanoparticles under the functional capping of poly(vinylpyrrolidone) (PVP). The nanobelts obtained exhibit a quantum size effect in optical properties, showing a blue shift of the band gap and direct transitions relative to the values of bulk t-Se.

Two kinds of new morphology of carbon nanomaterials, carbon nanocables and branched-nanobelts can been produced by pyrolyzing ethylene glycol monvethyl ether (CH3CH2OCH2CH2OH) with Fe as catalyst at 650–700 °C. The carbon nanocables are made of two parts, the interior carbon nanowires encapsulated in the outer carbon nanotubes. For the nanocables, HRTEM images reveal that the crystallinity of the outer carbon nanotubes is better than that of the interior carbon nanowires. HRTEM image shows that the junctions of the branched-nanobelts are composed of graphitic layers that are almost perpendicular to the respective axis of the branched-nanobelts. The catalysts, temperature and reaction time were investigated. The possible growth mechanism for the as-synthesized carbon structures is discussed.

SnS2 nanobelts were successfully synthesized through a controllable solution-phase hydrothermal method on a large scale. The nanobelts have a very high yield, which is more than 95%, with widths ranging from 100 to 200 nanometers, lengths up to several micrometers and thicknesses ca. 10 nanometers. X-ray diffraction patterns, electronic diffraction, X-ray photoelectron spectra, field emission scanning electron microscopy images, transmission electron microscopy images and high-resolution transmission electron microscopy investigated the phase structures, compositions, and morphologies of SnS2 nanobelts. Dodecanethiol played important roles in the process of SnS2 nanobelts formation and growth. The formation mechanism of SnS2 nanobelts was investigated and discussed on the basis of the experimental results.

The 3D beta-In2S3 flowerlike architecture assembled from nanoflakes was prepared via a novel complex-precursor assisted (CPA) solvothermal route. The as-prepared beta-In2S3 powder was characterized by X-ray diffraction pattern (XRD), X-ray photoelectron spectra (XPS), transition electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), ultraviolet-visible light (UV-vis) spectra, and photoluminescence spectrum. The novel 3D beta-In2S3 nanostructure exhibit a strong quantum confinement effect. FT-IR spectra were used to investigate the coordinative chemical effect in the complex. A possible mechanism was discussed.

The large-scale synthesis of antimony nanobelt bundles has been facilely realized in existence of polyethylene glycol (PEG) by a hydrothermal reduction method using aluminum powder as reducing agent. These nanobelts have width in the range of 200–600 nm and length up to several micrometres, and the width-to-thickness ratio is ca. 10. FESEM images show individual nanobelts have multi-layered structures. The size of nanobelts can be varied by adjusting the molecular weights of PEG. Based on a series of comparative experiments under different reaction conditions, the probable formation mechanism of antimony nanobelt bundles is proposed to be a solid–liquid–solid transformation and surfactant-assisted directional growth process.

A novel nanostructure, cubic silicon carbide (3C-SiC) nanoparticles encapsulated in branched wavelike carbon nanotubes have been prepared by a reaction of 1,2-dimenthoxyethane (CH3OCH2CH2OCH3), SiCl4, and Mg in an autoclave at 600 degrees C. According to X-ray powder diffraction, the products are composed of 3C-SiC and carbon. TEM and HRTEM images show that the as-synthesized products are composed of 3C-SiC nanoparticles encapsulated in branched carbon nanotubes with wavelike walls. The diameter of the 3C-SiC cores is approximately 20-40 nm and the thickness of the carbon shells is about 3-5 nm. In Raman scattering spectroscopy, both the TO (Gamma) phonon line and the LO (Gamma) phonon line have red shifts about 6 cm(-1) relative to that for the bulk 3C-SiC. The photoluminescence (PL) spectrum shows that there are two emission peaks: blue light emission (431 nm) and violet light emission (414 nm). A sequential deposition growth process (with cores as the templates for the shells) for the nanostructure was proposed.

A novel complex-assisted hydrothermal route is presented to fabricate ultralong Ag/C nanocables with length ranging from 100 to 180 microm on a large scale, based on the reaction of sulfamic acid silver and salicylic acid. By chemical etching of these Ag/C nanocables, high-quality carbonaceous nanotubes can be obtained at room temperature. Using the as-prepared Ag/C nanocables as templates, a new strategy for introducing guest materials into hollow nanotubes is addressed. We take Ag(2)Se as an example and validate the feasibility of this strategy. All of the products are characterized in detail by multiform techniques: X-ray diffraction, Fourier transform IR, energy-dispersive X-ray analysis, field emission scanning electron microscopy, transmission electron microscopy (TEM), and high-resolution TEM. The formation mechanisms of these products are tentatively proposed.

Single-crystalline PbI 2 nanobelt bundles have been prepared using lead monoxide powder and hydroiodic acid as reagents at the assistance of dodecylamine. The assembled PbI 2 nanobelt bundles can be spilt into nanobelts through long-playing sonication. The prepared nanobelt bundles consist of several nanobelts and the nanobelts have lengths of tens of microns, widths of 50-150 nanometers, and thicknesses ca. 20 nanometers. X-Ray diffraction (XRD), scanning electron microscopy (SEM), field emission scanning electron microscopy (FE-SEM) transmission electron microscopy (TEM), electronic diffraction (ED), and high-resolution transmission microscopy (HRTEM) was used to characterize the as-prepared product. The possible formation mechanism of PbI 2 nanobelt bundles was tentatively proposed.

SnS2 nanobelts were successfully synthesized through a controllable solution-phase hydrothermal method on a large scale. The nanobelts have a very high yield, which is more than 95%, with widths ranging from 100 to 200 nanometers, lengths up to several micrometers and thicknesses ca. 10 nanometers. X-ray diffraction patterns, electronic diffraction, X-ray photoelectron spectra, field emission scanning electron microscopy images, transmission electron microscopy images and high-resolution transmission electron microscopy investigated the phase structures, compositions, and morphologies of SnS2 nanobelts. Dodecanethiol played important roles in the process of SnS2 nanobelts formation and growth. The formation mechanism of SnS2 nanobelts was investigated and discussed on the basis of the experimental results.

The 3D beta-In2S3 flowerlike architecture assembled from nanoflakes was prepared via a novel complex-precursor assisted (CPA) solvothermal route. The as-prepared beta-In2S3 powder was characterized by X-ray diffraction pattern (XRD), X-ray photoelectron spectra (XPS), transition electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), ultraviolet-visible light (UV-vis) spectra, and photoluminescence spectrum. The novel 3D beta-In2S3 nanostructure exhibit a strong quantum confinement effect. FT-IR spectra were used to investigate the coordinative chemical effect in the complex. A possible mechanism was discussed.

In this letter a new synthetic strategy has been established for MoO 3 nanobelts by oxidizing Mo powders with H 2 O 2 in neutral water at 70 °C and a subsequent hydrothermal treatment at 140 °C. By introducing alcohol into this system, we can selectively prepare blue H x MoO 3 nanobelts. The photoluminescence (PL) property can be greatly altered before and after hydrogen incorporation into MoO 3 nanobelts. The mechanism on formation process of nanobelts has also been addressed.

A novel solvothermal route combined with calcination was successfully established to synthesize octahedral In2O3 particles, which exhibit near band emission. Interesting shape transformation from a...

Tellurium fibers are first synthesized through the reduction of Na2TeO4 by hydrazine hydrate. The as-prepared tellurium fibers are used as templates for further reaction with aqueous AgNO3 solution...

A simple method was used to prepare carbon hollow spheres with average size of about 400 nm in diameter from metal zinc powder and ethanol. The FE-SEM and TEM images show that these carbon spheres ...

Abstract In this paper, the surface of each tooth of roller bits is represented by scores of points, whose 3-D compound coordinates are used to reflect the shape and size of the tooth. Thus, the cutting structure of the bit together with their movement is represented by the time-sequence of the coordinates of the several thousand points. Hence, the computer simulates the roller bit. In the simulation, the bottom hole that changes with drilling is represented, according to the sequence of time, as a series of time points. And the bottom hole at each time point is represented, according to space, as tens of thousands of points, whose 3-D compound coordinates are used to express the shape and size of the bottom hole at an arbitrary time. The changes of the bottom hole with drilling are described by a recurrence model made up of the bottom hole at each time point. Hence the reproduction of the bottom hole is on computer. The well bore is dealt with the same principle as the bottom hole. The interaction between the roller bit and the rock is represented by the balance model of the vertical and the lateral interactions. The index, inclination, the shape and size of rock fragile breakage by a contacting tooth at any time are calculated by the fragile criterion model and the rock breakage model. The craters with various shapes are formed by the rock fragile breakage and the amount of the rock occupied by the tooth directly. BRIAS, the simulation software thus set up, can be used to analyse all the interactions in the process of drilling. Detailed experiment data have proved that the simulation software is able to well reflect the effects of the subtle differences of bit structure, WOB and rock properties upon the rotation rate and the torque of the bit. Introduction The content of the interaction between a roller bit and bottom rock is very extensive. This paper mainly deals with two major issues: how the bottom rock is smashed upon the force of the bit; How the roller bit moves under the action of the drilling string and the reaction of the bottom rock. The key problem here is the relative movement and the interaction between the tooth and the bottom hole. In fact, the movement of the bit can be analysed if the pressures upon the bit are available; the smashing of the rock can be studied if the pressures upon the rock are clear. P. 309

This paper describes a surfactant-assisted hydrothermal reduction pathway toward various kinds of antimony and bismuth three-dimensional superstructures, containing hollow spheres composed of nanostrips, peony-like architecture, radial sub-micrometer rod bundles, and a shale-like pattern. These three-dimensional superstructures were obtained through the reduction of SbCl3 or Bi(NO3)3·5H2O by aluminum powder in different emulsion systems at 120°C. The formation mechanism for Sb three-dimensional superstructures has been formally proposed. Some influencing factors on the morphology of the final products have also been discussed. We expect this convenient method can be extended to prepare three-dimensional superstructures of other inorganic materials, which have similar layered structures to Sb and Bi.