Effectiveness of participatory ergonomic interventions on musculoskeletal disorders and work ability among young dental professionals: A cluster-randomized controlled trail.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSION: 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.

Nanoscale electric-field imaging based on a quantum sensor and its charge-state control under ambient condition.

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. Here, using individual shallow NVs, we quantitatively image electric field contours from a sharp tip of a qPlus-based atomic force microscope (AFM), and achieve 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 the possibility of quantitatively mapping local charge, electric polarization, and dielectric response in a broad spectrum of functional materials at nanoscale.

Ergonomic risk exposure and work ability among young dental professionals in China: A cross-sectional study.

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.

New Insight into the Hierarchical Microsphere Evolution of Organic Three-Dimensional Layer Double Hydroxide: The Key Role of the Surfactant Template.

Surfactants have proven a suitable template agent for the construction of organic three-dimensional layered 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 about the key role of surfactants in the growth behavior and mechanism. In this study, sodium dodecyl sulfate (SDS) was chosen to identify the behavior of the surfactant on the evolution of O3D-LDH with various factors. The as-grown procedure was investigated by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and Brunauer-Emmett-Teller analysis. The results demonstrated that the ideal 3D roselike hierarchical structure was obtained at a Mg/Al/urea molar ratio of 2:1:10 and SDS concentration of 0.1 mol L-1 at 150 °C for 6 h. It is worth 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 an 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 provides a theoretical foundation for other LDH material construction.

Revealing the mechanism of contrasting charge transport properties for phenyl and thienyl substituent organic semiconductors.

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.

Investigating the Thermal Stability of Organic Thin-Film Transistors and Phototransistors Based on [1]-Benzothieno-[3,2-b]-[1]-benzothiophene Dimeric Derivatives.

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.

Investigation on the Behavior of Noise in Asynchronous Spectra in Generalized Two-Dimensional (2D) Correlation Spectroscopy and Application of Butterworth Filter in the Improvement of Signal-to-Noise Ratio of 2D Asynchronous Spectra.

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 ß-cyclodextrin is investigated using 2D UV-vis asynchronous spectra. When artificial noise is added, cross peaks that reflect intermolecular interaction between berberine and ß-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.

High Performance and Enhanced Durability of Thermochromic Films Using VO2@ZnO Core-Shell Nanoparticles.

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 thermochromic performance expresses good potential for practical application of VO2-based smart windows.