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Nitrogen-vacancy (NV) centers in diamond can be used as quantum sensors to image the magnetic field with nanoscale resolution. However, nanoscale electric-field mapping has not been achieved so far because of the relatively weak coupling strength between NV and electric field. Using individual shallow NVs, here we succeeded to quantitatively image the contours of electric field from a sharp tip of a qPlus-based atomic force microscope (AFM), and achieved a spatial resolution of ~10 nm. Through such local electric fields, we demonstrated electric control of NV's charge state with sub-5 nm precision. This work represents the first step towards nanoscale scanning electrometry based on a single quantum sensor and may open up new possibility of quantitatively mapping local charge, electric polarization, and dielectric response in a broad spectrum of functional materials at nanoscale., Comment: 32 pages, 5 figures

This study is to evaluate the efficacy of participatory ergonomic (PE) intervention on musculoskeletal disorders (MSDs) and work ability among young dental professionals in China.A cluster randomized controlled trail was conducted during 2015-2016. Twenty-nine departments from five hospitals in the South of China were randomized into intervention (14 departments) and control (15 departments), with individuals of 125 and 138 dental professionals, respectively. Main participatory ergonomic interventions involved work posture, repetitive motions, tool usage, work break relaxation and work time re-arrangement with total 235 ergonomic changes in the trail. Individual ergonomic risk exposure was assessed by investigator's observation using quick exposure check (QEC). Work ability index (WAI) and MSDs were collected by questionnaires at baseline, and every 3 months during the 1-year follow-up.Follow-up rate was 91% and 96% for the intervention and control group, respectively. Significant reductions in ergonomic risk exposure and MSD prevalence on six anatomic sites were found in the PE group during the different follow-up stages. WAI scores improved by 1.1 (95% CI 0.43, 1.89) after the 9-month intervention. Compared to the control, the PE participants significantly reduced MSDs on neck (OR = 2.93, 95% CI: 1.25, 4.03) and wrists/hands (OR = 2.33, 95% CI: 1.08, 4.21), marginally increased WAI scores by 0.53 (95% CI: -0.02, 1.56) due to the interventions.PE intervention is effective in reducing ergonomic risk exposure and MSDs on neck and wrists/hands among young dental professionals. PE ought to be offered in the early dental career for preventing MSDs.

Ammonium (NH4+) has been causing severe environmental pollution while the development of material with high capacity for ammonium removal remains a challenge. Herein, the cement-based material tricalcium aluminate (C3A) was employed to remove NH4+ from digested piggery wastewater. The conditions influencing the removal capacity were investigated, including contact time, initial ammonium concentration, temperature, dosage and initial co-existing phosphate concentration. The physicochemical structure of C3A and the resultant were characterized by X-ray diffraction (XRD), Fourier transformed infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption isotherms. The maximum removal capacity of NH4+ by C3A was 155.4 mg·g−1 at 298 K. The characterization revealed that the resultant was CaAl-Cl-LDH. The hydroxyl groups and Al(OH)4− from the C3A hydration played an important role in ammonium removal. High alkalinity could enhance the removal capacity. This work presents an efficient solution for ammonium removal, thus providing new insight into the mechanism of cement-based materials for water pollutant removal.

The aromatic substituents such as phenyl and thienyl have a direct impact on the structure-property relationship of conjugated semiconducting molecules and thus play a significant role in determining the performance of organic thin film transistors (OTFTs). To design a molecule with good charge transport properties, it is essential to understand the charge transfer process. Herein, through the study of two groups of classical OTFT materials with different substituents, we demonstrate the fundamental reasons for the contrasting carrier mobilities between the materials in each group by means of DFT calculations. The results from our theoretical analysis on the two groups of molecules provide very good estimates of their charge transfer properties and the numerical trend from our calculation is consistent with that from the corresponding experimental results. We reveal in detail the impacts of the subtle geometric differences caused by different substituents from two aspects including (i) the significant influence of steric hindrance on reorganization energy and (ii) the overlap of the adjacent molecular orbitals (MOs) on electron coupling. Overall, our systematic investigation into the charge transfer mechanism and geometry effects allows us to employ a reliable theoretical methodology for the prediction of the material performance, which is crucial for the design of high performance OTFT materials.

Background Exposure to high ergonomic risk resulted in an increasing prevalence of musculoskeletal disorders among dental professional. However, little is known about the high exposure risk impact on work ability among dental professionals. Objective We conducted a cross-sectional study to examine the association between ergonomic risk exposure and work ability among young dental professionals in their early careers. Methods A total of 230 dental professionals including dentists, dental assistants, and nurses were clustered sampled from three hospitals in Guangzhou, south of China. We used the Quick Ergonomic Check (QEC) to assess participants' ergonomic risk exposure and Work Ability Index (WAI) to evaluate their work ability. Demographics and other factors related with WAI were also included in the data collection. Multiple linear regression was applied to analyze the association between ergonomic exposure scores and WAI. Results A total of 218 participants (94.8%) had valid data and consent forms. The participants' average WAI was 39.6, of which the poor and moderate WAI composed 31%. High and very high ergonomic risk exposure level was 45.9% for the neck and 21.1% for the wrist/hand. In general, WAI decreased with higher ergonomic exposure level. With adjustment of other potential risk factors, the ergonomic scores for wrist/hand and total scores for the whole body were significantly associated with the decreased WAI. Conclusion High ergonomic risk exposure might risk in reducing work ability among young dental professionals. Intervention measures toward ergonomic risk should be taken to prevent WAI from decreasing in their early careers.

Anthracene derivatives constitute the active elements in high performance organic semiconductors and in order to find ubiquitous electronics applications, the investigation of new materials with high stability and mobilities is critical. Despite the versatility of substituent groups in anthracene and the extensive research works on anthracene derivatives, the exploration and discovery of high-performance anthracene derivatives can be impeded by the difficulty in molecular designing and synthesis techniques. Theoretical modeling is a powerful instrument and a variety of modeling methods with different accuracy levels have been reported. However, there is no systematic research work on theoretical prediction of the fundamental properties of anthracene derivatives so far. Here, density functional theory calculations are performed on anthracene derivatives to systematically address the prediction accuracy in energy levels as compared to our experimental data and it is shown that the PBE0/6-311G(d,p) is a more cost-effective method. Based on the influence of diverse substituent groups on energy levels, we present a strategy to design high-performance anthracene derivatives with specific energy levels, which are predicted to be excellent candidates for charge transfer materials. Therefore, the strategy may offer a guide for tailoring materials' functional properties via modifications of the molecular units before materials synthesis and open up new possibilities for the discovery of rising organic semiconductors.

In the quest for solution-processable red electrochromic material with high performance, a series of 3,6-bis(dodecyloxy)thieno[3,2-b]thiophene (DOTT)-based polymers have been designed by combining DOTT with different aromatic building blocks (bithiophene, benzene, and dimethoxybenzene) and prepared through Pd-catalyzed chemical copolymerization. Among them, the solution-processable polymer poly(2,5-dimethoxyphenyl-1,4-diyl-3,6-bis(dodecyloxy)thieno[3,2-b]thiophene) (P3) showed obvious yellow-green fluorescence in chloroform and demonstrated a rapid reversible switching (1.1 s/0.9 s for doping/dedoping process) between the red and bleached states. This brilliant red polymer exhibited moderate contrast (46% at 510 nm) and excellent cycling stability (in film: 78% for total amount and 63% for reduction after 12000 cycles; in device: 85.6% after 3000 cycles) which qualify it for further device fabrications. This study reveals that this polymer (P3) would be a promising high performance red electrochrome and c...

Cesium-doped tungsten bronze Cs x WO 3 (CWO) is a promising candidate for near-infrared (NIR) shielding materials on windows of buildings and automobiles. However, the NIR shielding ability of CWO easily deteriorates in hot humid and alkaline environments, which hinders further applications of CWO. In this paper, we firstly reported a novel core-shell structure of CWO@ZnO, which exhibited high NIR shielding performance with excellent stability. In hot humid environment, CWO@ZnO nanoparticles kept their outstanding NIR shielding ability after 150 days while uncoated CWO nanoparticles showed an evident deterioration in just 1 day. Moreover, the CWO@ZnO core-shell structure also exhibits excellent stability in alkaline environment. The good protection of the uniform, continuous and compact ZnO shells played an important role on enhancing the stabilities of CWO nanoparticles. This study provides a novel route for promoting the practical applications of CWO NIR shielding materials.

For VO2-based thermochromic smart windows, high luminous transmittance (Tlum) and solar regulation efficiency (ΔTsol) are usually pursued as the most critical issues, which have been discussed in numerous researches. However, environmental durability, which has rarely been considered, is also so vital for practical application because it determines lifetime and cycle times of smart windows. In this paper, we report novel VO2@ZnO core–shell nanoparticles with ultrahigh durability as well as improved thermochromic performance. The VO2@ZnO nanoparticles-based thermochromic film exhibits a robust durability that the ΔTsol keeps 77% (from 19.1% to 14.7%) after 103 hours in a hyperthermal and humid environment, while a relevant property of uncoated VO2 nanoparticles-based film badly deteriorates after 30 h. Meanwhile, compared with the uncoated VO2-based film, the VO2@ZnO-based film demonstrates an 11.0% increase (from 17.2% to 19.1%) in ΔTsol and a 31.1% increase (from 38.9% to 51.0%) in Tlum. Such integrated ...

VO 2 /Al-O core-shell structure (V/AO) was synthesized by a facile method and its application for thermochromic film on smart window was investigated. Comparisons of thermochromic properties and stabilities in different environments between VO 2 and annealed V/AO nanoparticles were made. As a result, VO 2 nanoparticle was easily oxidized and lost thermochromic property. In contrast, with the protection provided by Al-O-based shell, the VO 2 core remained stable at a high temperature (350 °C in air) and in H 2 O 2 solution. Especially, thermochromic films made by annealed V/AO nanoparticles almost kept thermochromic performance in damp heating environment (T=60 °C, RH=90%) for 20 days while VO 2 films lost their thermochromic properties after 3 days. Besides, the degradation progress of VO 2 and V/AO nanoparticles in damp heating environment was also explored. Results indicate that Al-O-based shell provides a good protection for the VO 2 core originated from the compact structure of shell, which effectively prevents oxygen and water from eroding VO 2 . In summary, the VO 2 nanoparticles coated with Al-O-based shell exhibit a great potential in the application of smart window.

Surfactants have proven a suitable template agent for the construction of organic three-dimensional layer double hydroxide (O3D-LDH) due to the excellent self-assembled property and ready operation. Although the morphology and growth of O3D-LDH are affected by various factors (initial surfactant concentration, Mg/Al molar ratio, hydrothermal temperature, urea concentration, hydrothermal time, etc.), little is known on the key role of surfactants for the growth behavior and mechanism. In this study, sodium dodecyl sulphate (SDS) was chosen to identify the behavior of surfactant on the evolution of O3D-LDH with various factors. The as-grown procedure was investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and Brunauer-Emmelt-Teller (BET) analysis. The results demonstrated that the ideal 3D rose-like hierarchical structure was obtained at Mg/Al/urea molar ratio=2:1:10 and SDS concentration of 0.1 mol·L-1 at 150 o C for 6 h. It was worthwhile noting that SDS showed an extraordinary importance regarding the material growth, as it was intrinsically related to the formation of spherical micelles and functioned as intercalating anion. Furthermore, a possible growth mechanism was proposed to explain the formation of O3D-LDH. Our finding opens a new insight into the role of SDS in the O3D-LDH fabrication and provide a theoretical foundation for other LDHs material construction.

Two new highly thermally stable [1]benzothieno[3,2-b][1]benzothiophene (BTBT) dimeric derivatives, namely 1,4-bis([1]benzothieno[3,2-b][1]benzothiophene-2-yl)benzene (BTBT-Ph-BTBT) and 4,4'-bis([1]benzothieno[3,2-b][1]benzothiophene-2-yl)-1,1'-biphenyl (BTBT-DPh-BTBT), were synthesized by combining two simple fragment structures. Compared to the monomer compound 2-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT, μmax =3.4×10-2 cm2 V-1 s-1 ), the organic thin-film transistors (OTFTs) based on BTBT-Ph-BTBT and BTBT-DPh-BTBT showed significantly higher mobility (up to 2.5 and 3.6 cm2 V-1 s-1 for BTBT-Ph-BTBT and BTBT-DPh-BTBT, respectively). The mobility of OTFTs based on BTBT-Ph-BTBT was kept at a high value (2.4×10-1 cm2 V-1 s-1 ) after the devices were thermally annealed at 350 °C. Furthermore, the organic phototransistors (OPTs) based on BTBT-Ph-BTBT and BTBT-DPh-BTBT displayed high photosensitivities in a range of 250-400 nm with a low intensity, making these materials potentially applicable for sensitive optoelectronic devices.

We report the first observation of the non-magnetic Barkhausen effect in van der Waals layered crystals, specifically, during transitions between the T d and 1T' phases in type-II Weyl semimetal MoTe2. Thinning down the MoTe2 crystal from bulk material to about 25 nm results in a drastic strengthening of the hysteresis in the phase transition, with the difference in critical temperature increasing from ~40 K to more than 300 K. The Barkhausen effect appears for thin samples and the temperature range of the Barkhausen zone grows approximately linearly with reducing sample thickness, pointing to a surface origin of the phase pinning effects. The distribution of the Barkhausen jumps shows a power law behavior, with its critical exponent α = 1.27, in good agreement with existing scaling theory. Temperature-dependent Raman spectroscopy on MoTe2 crystals of various thicknesses shows results consistent with our transport measurements.

Cesium-doped tungsten bronze CsxWO3 is an ideal near infrared (NIR) shielding material for solar filters. However, the CsxWO3 nanoparticle dispersed resin film exhibits obvious photochromic behavior under ultraviolet (UV) illumination, which severely hinders the commercial application of CsxWO3. In this paper, CsxWO3/SiO2 composite resin coatings were successfully prepared with excellent NIR shielding ability and outstanding optical stability under strong UV illumination by combining an ultraviolet-absorbing agent (UVA) with SiO2. The roles of UVA and SiO2 in preventing the photochromic behavior of the CsxWO3/SiO2 composite resin coating were vital, reducing the photochromic reaction rate by UVA and limiting the photochromic reaction areas by SiO2. In sum, our research provides a new solution for eliminating the photochromism of a CsxWO3-based resin film and it may have practical application in architecture and automobiles.

The behavior of noise in asynchronous spectrum in generalized two-dimensional (2D) correlation spectroscopy is investigated. Mathematical analysis on the noise of 2D spectra and computer simulation on a model system show that the fluctuation of noise in a 2D asynchronous spectrum can be characterized by the standard deviation of noise in 1D spectra. Furthermore, a new approach to improve a signal-to-noise ratio of 2D asynchronous spectrum by a Butterworth filter is developed. A strategy to determine the optimal conditions is proposed. Computer simulation on a model system indicates that the noise of 2D asynchronous spectrum can be significantly suppressed using the Butterworth filtering. In addition, we have tested the approach to a real chemical system where interaction between berberine and β-cyclodextrin is investigated using 2D UV-vis asynchronous spectra. When artificial noise is added, cross peaks that reflect intermolecular interaction between berberine and β-cyclodextrin are completely masked by noise. After the method described in this article is utilized, noise is effectively suppressed, and cross peaks are faithfully recovered. The above result demonstrates that the approach described in this article is applicable in real chemical systems.

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