Search

[Display omitted] • Experimentally examined the impact of varying the junction angle on droplet size. • Four flow regimes were identified: Parallel flow, Jetting, Dripping and Squeezing. • A scaling law containing the junction angle is proposed to predict droplet lengths. • Estimated the volumes of droplets, slugs, and unit cells based on 2-D snapshots. Liquid-liquid two-phase flow in T-inlet microchannels with different junction angles (θ = 30°, 60°, 90°, 120° and 150°) was investigated experimentally. Four flow regimes of the dispersed phase were identified, i.e., parallel flow, jetting, dripping and squeezing, and the distribution of flow regimes for the dispersed phase corresponding to variations in the junction angle was plotted. The consequences of varying junction angle and flow conditions in the squeezing regime on the generated droplet size were analyzed. The results indicate that low capillary number and large flow rate ratio are conducive to the formation of large-size droplets. For constant flow conditions, junction angle θ = 90° is detrimental to the formation of squeezing microdroplets. The increase in microchannel junction angle causes the droplet size to decrease until θ > 90°, where the droplet size increases with the junction angle. On the basis of experimental results, the scaling law correlation equations containing the junction angle for predicting the droplet length and droplet volume are proposed, respectively. The predicted values match well with the experimental data. The results of this work contribute to the enhancement of the monodispersity of microdroplets and the precise control over a wide range of the generated droplet size by adjusting the junction angle. [ABSTRACT FROM AUTHOR]

Pain is a hallmark symptom associated with intestinal inflammation. Two related articles published in Cell by Zhang et al. and by Yang et al. now report how sensory neurons in the gut, the most heavily innervated organ in the human body, flag bacterial pathogens to shape the composition of the gut microbiome and to trigger immunoregulatory mechanisms. [ABSTRACT FROM AUTHOR]

Due to the advantages including high efficiency and environmental friendliness, the two-dimensional thermoelectric materials have received huge attention. However, the energy conversion efficiency is not high enough for application. In this work, we have theoretically investigated the thermoelectric performance for both zigzag (ZGeNRs) and armchair (AGeNRs) germanene nanoribbons with edge defects by nonequilibrium Green's function method. For perfect germanene nanoribbons (GeNRs), it is shown that with its width increasing, the maximum of ZT values (ZT max) decreases monotonously while the phononic thermal conductance increases linearly. For both ZGeNRs and AGeNRs, with increasing defect numbers in longitudinal direction, ZT max increases monotonously while the phononic thermal conductance decreases. In particular, by introducing periodic defects, the ZT max of both ZGeNRs and AGeNRs has been raised to above 2, which is due to higher Seebeck coefficient and lower thermal conductance. Our findings provide an effective way to enhance thermoelectric performance, which is beneficial for the design of ultra-thin thermoelectric devices. • For perfect GeNRs, the ZT max decreases monotonously with its width increasing. • For defected GeNRs, the ZT max increases monotonously with increasing defect numbers. • The ZT max of both ZGeNRs and AGeNRs has been raised to above 2. [ABSTRACT FROM AUTHOR]

Abstract: La2O2S:Yb,Pr nanometer phosphor have been prepared by a novel ethanol-assistant solution combustion (EASC) method in ethanol–water solution medium via a relatively mild and slow combustion process, using ethanol as preigniting fuel and inexpensive thioacetamide as sulfur-containing organic fuel. Investigation results show: ethanol preigniting serves the role of ignition combustion decomposition reaction between rare earth nitrate and organic fuel and promotes the formation of uniform and less agglomerative rare earth oxysulfide nanocrystals. Single phase Ln2O2S:Yb,Pr nanocrystals are obtained with appropriate ethanol/water ratio and further annealing at 1000°C for 2h in reduced atmosphere. The La2O2S:Yb,Pr nanocrystals exhibit an intense green emission assigned to the Pr3+ ions 3P0 → 3H4 transition and a broad near infrared (NIR) emission under 980nm pump. The defects residing in La2O2S:Yb,Pr nanocrystals is the probable origins for the NIR emission. The annealing process makes the green emission improve and the NIR emission weaken. After annealing treatment at 1000°C, the upconversion luminescence intensity is close to that of the bulk sample prepared by a solid-state reaction method. [Copyright &y& Elsevier]

Abstract: Characteristic and synthesis mechanism of Gd2O2S:Tb X-ray phosphors prepared by cold isostatic press (CIP) pretreatment have been investigated by photoluminescence (PL) spectra, luminescence spectra under X-ray excitation (XL), X-ray diffraction (XRD) and scanning electric microscope (SEM). It is shown that the pre-pressed technology reduces the sintering temperature with about 100°C. It also decreases the particle size, influences the particle size distribution and morphology, and enhances the luminescence efficiencies of PL and XL of Gd2O2S:Tb phosphors greatly. CIP technique also promotes the formation of Gd2O2S by breaking the starting Gd2O3 particles down to smaller particles as well as retarding the sulphur volatilization at low temperature. The nucleation site density in CIP process is higher than that of the normal technology; the cumulative contribution of the possible increase of the nucleation site numbers and the closer packing of the green body, results in finer and more uniform Gd2O2S:Tb particles. [Copyright &y& Elsevier]

Abstract: The Gd2O2S:Tb X-ray nano-phosphors were prepared using the complex precipitation method combined with low temperature sulfurized method. The mixed solution of the ammonium water and ammonium hydrogen carbonate was employed as the complex precipitant. The samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), photoluminescence (PL) and X-ray excited luminescence (XL) spectra. The results show that the as-prepared samples can be sulfurized completely at 900°C with flowing N2 containing sulfur vapor, and show the pure Gd2O2S phases with the hexagonal structure. The obtained X-ray phosphor particles are quasi-spherical, disperse well. And the observed particle size of the sample calcined at 900°C is 30–50nm, while the one calcined at 1100°C is about 50–70nm. Therefore, both of them have successfully realized the nano-sized, which are beneficial to enhance the resolution of imaging system efficiently. When excited by the 254nm UV light and X-ray, the Gd2O2S:Tb X-phosphors exhibit the same characteristic emission of Tb3+, which arise from the transitions of 5D3 and 5D4 excited levels to 7F J (J =0–6) ground states. And the luminescence property of the nanocrystals and the process of energy transfer are studied in details. [Copyright &y& Elsevier]

Heteroatom-modified carbon-based catalysts (especially nitrogen-doped) have been reported to be effective in activating peroxymonosulfate (PMS). Nevertheless, here our study found that graphitized carbon nanomaterial (GC800) exhibited a similar catalytic capacity as the nitrogen-doped graphitized carbon nanomaterial (NGC800) in the degradation of bisphenol A (BPA) via activating PMS, however, the degradation rate constant of the former was approximately 1.72-times greater than that of the latter. Meanwhile, GC800 showed admirable versatility, wide application range of pH value and excellent stability. Furthermore, the connection between the difference in surface chemistry (surface functional groups, electronic properties) and reaction rate between GC800 and NGC800 was discussed. Quenching experiments combined with electron paramagnetic resonance (EPR) and electrochemical measurements revealed the existence of a multi-pathway synergy in GC800/PMS system dominated by the non-radical electron-transfer pathway and complemented by radical (O 2 •−)/non-radical (1O 2) pathway. The high proportion of carbonyl groups and sp2-hybridized carbon as the main parameters affected the electron density of GC800 in the process of non-radical electron transfer. In contrast, NGC800/PMS system only followed the non-radical oxidation pathway with singlet oxygen being the predominant ROS. Pyrrolic N affected the non-radical oxidation pathway of NGC800. This work verifies the significant role of surface chemistry of carbon materials and the synergy between non-radical electron transfer and radical/non-radical oxidation on the catalytic velocity. And it presents a novel thought in the design of high-efficiency carbon-based catalysts toward green and sustainable ecological restoration. Take catalytic activity of catalysts as the object of study, the mechanism differences and determining factors of GC800/PMS/BPA system and NGC800/PMS/BPA system were investigated. [Display omitted] ● N-doped and non-doped graphitized catalysts were prepared by thermal annealing. ● GC800 shows much higher rate constant than NGC800 in activating PMS to degrade BPA. ● Surface chemistry of GC800 and NGC800 are key factor affecting catalytic velocity. ● Activation of PMS on GC800 mainly relied on the synergy of multi-reaction pathway. ● Activation of PMS on NGC800 followed non-radical pathway mainly producing 1O 2. [ABSTRACT FROM AUTHOR]

We have studied the conductance anisotropy of bilayer black phosphorene under chemical potential or external electric fields based on the non-equilibrium Green's function method. The results have shown that the chemical potential has a huge impact on the direction and magnitude of the conductance anisotropy of bilayer black phosphorene, which beyond those of monolayer. In addition, it is found that the interlayer coupling enhances the conductance anisotropy on the valence band maximum. Particularly, the conductance anisotropy can be greatly modulated by external electric field, and the direction of the maximum and minimum conductance can be even reversed by external electric field. The controllability between the interlayer coupling and the conductance anisotropy with external field is of interest to the field of nano-electronics and have some technical promise. • We have studied the conductance anisotropy of bilayer black phosphorene under chemical potential or external electric fields. • The results have shown that the chemical potential has a huge impact on the direction and magnitude of the conductance anisotropy. • It is found that the interlayer coupling enhances the conductance anisotropy on the valence band maximum. • The direction of the maximum and minimum conductance can be even reversed by external electric field. [ABSTRACT FROM AUTHOR]

Abstract: The up-conversion luminescence properties of trivalent-rare-earth ion-doped orthotantalates are studied under 980 nm laser diode excitation. The results indicate that YTaO4:Tm3+/Yb3+ emits blue and strong infrared emissions respectively corresponding to 1G4→3H6 and 3H4→3H6 transitions of Tm3+ ions, while YTaO4:Er3+/Yb3+ produces strong green and weak red emissions, resulting from 2H11/2/4S3/2→4I15/2 and 4F9/2→4I15/2 transitions of Er3+ ions, respectively. In contrast to three excellent up-conversion phosphors, viz. NaYF4:Er3+/Yb3+, Y2O2S:Er3+/Yb3+ and Y2O3:Er3+, YTaO4:Er3+/Yb3+ shows not only strong green emission, but also larger intensity ratio of green to red emission. In addition, it is found that LaTaO4: Er3+/Yb3+ shows the minimum quenching concentration of Yb3+ and weakest up-conversion emission intensity, and the main peak presents blue shift (8 nm/556 nm) as compared with YTaO4:Er3+/Yb3+ and GdTaO4:Er3+/Yb3+. The distinct luminescent characteristics of LaTaO4: Er3+/Yb3+ can be attributed to the larger difference of radius between doped ion and La3+ ion. [Copyright &y& Elsevier]

In this study, a novel 3D flower-sphere BiOBr/Bi 4 O 5 Br 2 with proper-oxygen vacancies (OV) was successfully synthesized by using 3D BiOBr as a self-sacrificed template, NaOH as a structure-driving reagent and midwifery agent of OV. The synthesis mechanism was systematically studied. It revealed that Bi 4 O 5 Br 2 lamina generated via in-situ phase transfer tightly interspersed in the interior and surface of 3D BiOBr hierarchical structures; calcination temperature, stirring time and –OH concentration can optimize the composition and structure of materials. Also, the calcination conditions (temperatures and air or N 2 atmosphere) can regulate the OV's concentration. Ultimately, 3D hierarchical architectures, the optimal heterojunction composition and OV with proper concentrations three positive factors synergistically promoted the photoelectric activity of BiOBr/Bi 4 O 5 Br 2 –OV, making it exhibit ultrahigh photocatalytic activity for antibiotic photodegradation (tetracycline, TC; ciprofloxacin, CIP). We believe the synthesis methods and design idea mentioned in this paper have high instructive significance to prepare high-performance materials. Unlabelled Image • A novel 3D flower-sphere BiOBr/Bi 4 O 5 Br 2 with proper-OV was successfully synthesized. • A new, facile and controllable synthesize method for 3D rich-Bi materials with OV were proposed. • NaOH acted as a structure-driving reagent and midwifery agent of OV. • BiOBr/Bi 4 O 5 Br 2 -OV exhibited the highest photocatalytic activity for TC and CIP. • OV with proper concentrations highly improved e− migration ability, boosting more O 2 activation. [ABSTRACT FROM AUTHOR]

A novel Fenton-like catalyst with a hollow meso -crystalline Fe 3 O 4 catalyst doped with Mn was prepared for the first time through a one-pot method, which can achieve rapid degradation of ciprofloxacin (CIP) under the conditions of pH=4.5 to pH=9.5 and greatly expands the application conditions of Fenton. The formation process of the catalyst was reasonably analyzed based on Ostwald curing theory and bubble theory. And the dual reaction center theory reasonably explains the Fenton reaction mechanism of the catalyst. [Display omitted] • A novel catalyst hollow meso -crystalline Mn-doped Fe 3 O 4 was prepared by one-pot method. • The catalyst has excellent magnetic properties and stability. • Ciprofloxacin was efficiently degraded over a wide pH range of 4.5–9.5. • The formation of Fe-Mn dual-reaction-centers validly promotes electron transfer. • •OH and 1O 2 were the dominant reactive oxygen species for ciprofloxacin degradation. Herein, an unprecedented heterogeneous Fenton-like catalyst with a hollow meso -crystalline Fe 3 O 4 catalyst doped with Mn was prepared for the first time through a one-pot method, which can effectively activate H 2 O 2 in a wide pH range and has good stability. The results show the catalyst can achieve rapid degradation of ciprofloxacin (CIP) under the conditions of pH = 4.5 to pH = 9.5, which greatly expands the application conditions of Fenton. Sufficient experimental exploration clearly demonstrated that the uniform doping of Mn in Fe 3 O 4 crystal lattice, and the formation process of Mn-doped Fe 3 O 4 hollow meso -crystalline microspheres was reasonably analyzed based on Ostwald curing theory and bubble theory. The dual reaction center theory reasonably explains the reaction mechanism of the catalyst. The H 2 O 2 adsorbed on the electron-rich Fe center is reduced to •OH, while the H 2 O 2 adsorbed on the electron-deficient Mn center is oxidized to •O 2 –/HO 2 •, •OH and •O 2 –/HO 2 • are further converted to 1O 2 , which participates in involved in the degradation process of CIP. This research provides new ideas for the rational design of catalysts that can apply the heterogeneous Fenton reaction to actual water purification in a wide pH range. [ABSTRACT FROM AUTHOR]

In seasonally frozen ground regions, freeze-thaw (F-T) cycles induce frost heave and affect the long-term stability of high-speed railway embankments. This study used a molecular vibration infrared nano-thermoprobe (MVINT) to address frost heave by actively heating embankments. Both embankments, one with MVINT and the other without, underwent five F-T cycles in a refrigeration room. The temperatures, unfrozen water contents, and vertical deformations of the two embankments were monitored and compared for analyzing the frost heave mitigation effect of MVINT. After undergoing five F-T cycles, the proportion of negative temperature area in the embankment without MVINT reached 66.45%. In contrast, the embankment with MVINT exhibited significantly higher temperatures than its counterpart without MVINT. Its negative temperature area accounts for 4.61% and can only be observed at the slope toe. The results indicate that the heat provided by MVINT can significantly increase the overall temperature of the embankment. The unfrozen water content of the embankment without MVINT exhibits periodic fluctuations, whereas that of the embankment with MVINT gradually decreased and stabilized at 18.1%. Furthermore, the vertical deformations at the top surface of the embankment without MVINT are greater than those with MVINT. The maximum vertical deformation difference at the centerline of the two embankments is 1.07 mm, and the maximum vertical deformation difference at the shoulder is 0.67 mm. These demonstrate that the heat generated by MVINT effectively warms the embankment and reduces frozen depth. Therefore, MVINT is proved to be a reliable solution for mitigating frost heave in seasonally frozen ground regions. • A novel embankment with MVINT was proposed to address frost heave of the embankment. • The temperature, unfrozen water content and vertical deformation were monitored. • The MVINT changed hydrothermal conditions in the embankment. • The MVINT effectively mitigated frost heave of the embankment in the seasonally frozen regions. [ABSTRACT FROM AUTHOR]

• The spectral data are pre-processed using three dimensionality reduction algorithms. • Optimize the parameters of the dimensionality reduction algorithm. • Establishment of a high-precision grade inversion model for Derni copper deposit. At present, chemical analysis is the main method for copper ore grade verification. Because of its long test cycle and lag effect relative to mining and ore blending processes, this approach cannot effectively reduce losses in mineral resource mining. An effective way to solve this problem is to conduct research on in situ grade determination methods for ore bodies based on visible-near-infrared hyperspectral grade modelling techniques. However, the accuracy of the modelling is seriously reduced by the large redundancy of hyperspectral data and the self-limiting nature of some machine learning methods. Therefore, the accurate selection of dimensionality reduction algorithms and machine learning algorithms determines the accuracy of the inverse model, and the setting of parameters such as dimensionality reduction, number of nearest neighbour points and number of hidden layers in neural networks is crucial. In this paper, 190 ore samples were collected from the open pit of the Derni copper deposit in Dawu town, Guoluo Tibetan Autonomous Prefecture, Qinghai Province, China. First, the visible-near-infrared spectral data for the sample set were obtained with an SVC HR-1024 spectrometer. The copper grade of the sample set was verified by chemical analysis. Three algorithms—the Laplacian eigenmap (LE), local tangent space alignment (LTSA) and local linear embedding (LLE)—were used to reduce the dimensionality of the original hyperspectral data. The original data and the three hyperspectral datasets after dimensionality reduction were used as data sources. Several Derni copper grade inversion models based on two machine learning algorithms, the backpropagation neural network and radial basis function (RBF) neural network, were developed. Finally, the coefficient of determination (R2), mean absolute error (MAE) and root mean square error (RMSE) were used to evaluate the accuracy of each model. The results show that the accuracy of the model built with spectral data processed by the dimension reduction algorithm is higher than that of the model constructed with the original spectral data. Among the above combined models, the LLE-RBF model has the highest inversion accuracy. The MAE of the model is 0.117%, the RMSE is 0.136, and R2 is 0.934. [ABSTRACT FROM AUTHOR]

Lifestyle interventions have been widely used to manage obesity, but their effects vary across individuals. Personality traits have increasingly drawn researchers' interest in exploring their role in obesity interventions, but study findings remain mixed. We aimed to systematically review and assess the associations between personality traits and the response to lifestyle-based obesity interventions for adult obesity. We searched PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science, PsycINFO, Scopus, Clinicaltrials.gov registry, and MedRxiv until February 8, 2023, and studies were screened as per the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) guidelines. We grouped personality traits into 5 superordinate traits according to the widely used Five-Factor model (FFM) and synthesized the results within each superordinate trait quantitatively (using meta-analyses) or narratively. We also used bubble plots to visualize patterns and trends within the results. We identified 3289 records and ultimately included 9 eligible studies in this review. We found that high conscientiousness tended to be positively associated with the response to lifestyle interventions for adult obesity and that low novelty seeking might be the main subordinate trait belonging to conscientiousness that was related to the intervention effect. Most of the included studies were rated as having a risk of bias due to inadequacy in comparisons of baseline characteristics or a short follow-up. Overall, studies included in this review are scarce, and more high-quality research of the present topic is urgently needed to inform individualized interventions for adult obesity stratified by personality traits. • High conscientiousness tended to be positively associated with the response to lifestyle interventions for adult obesity. • Low novelty seeking might be the main facet of Conscientiousness that was related to the intervention effect. • Studies in this field were still scarce in both quantity and quality. [ABSTRACT FROM AUTHOR]

• Combination of multiple pre-processing methods to comprehensively process raw spectral data. • The advantages of this method are high accuracy. • A method for selecting the optimal principle of spectral index is proposed. With saline-alkali land in Zhenlai County, Baicheng city, Jilin Province, China as the research object, a quantitative inversion model for the heavy metal content of manganese (Mn), cobalt (Co) and iron (Fe) in saline-alkali soil and the visible-near-infrared spectroscopy data were established. First, Savitzky-Golay (SG) smoothing, multivariate scattering correction (MSC), continuum removal (CR), and combined transformation methods were performed on the original spectral data. By analysing the correlation between processed data and heavy metal content, the characteristic bands corresponding to different spectral transformations were extracted. Next, the ratio index (RI), difference index (DI) and normalized difference index (NDI) were constructed, and the spectral index was determined to have the most significant correlation with the combination of Mn-, Co- and Fe-content-sensitive bands and its corresponding Spearman rank correlation coefficient. Finally, a quantitative inversion model for the heavy metal content (Mn, Co and Fe) in soda saline-alkali land was established, and its accuracy was verified. The research results show that the optimal band selection principle for the quantitative inversion model of heavy metals in soda saline-alkali land is as follows: Mn selected 219 groups of sensitive bands with correlation coefficient r > 0.70, Co selected 1377 groups of sensitive bands with correlation coefficient r > 0.80, and Fe selected 104 groups of sensitive bands with correlation coefficient r > 0.80. Based on these selection principles, the random forest algorithm was used to perform an inversion for the Mn, Co and Fe contents with the best results, the goodness of fit (R2) values between predicted and measured values were 0.76, 0.92 and 0.91, and the mean relative accuracy was 91.75%, 92.45% and 93.90%, respectively. This method has improved prediction accuracy of the Mn, Co and Fe contents in saline-alkali land. [ABSTRACT FROM AUTHOR]

• Four mass transfer states of droplets were photographed by the Schlieren method. • Numerical simulation of droplet formation with Marangoni instability. • Flow evolution during droplet formation under the Marangoni effect. • Effect of Marangoni instability on interfacial tension and vortex intensity. The Marangoni effect produces some complex phenomena during droplet formation and has an important influence on the mass transfer state. In this paper, the droplet formation process of toluene/acetone/water droplet extraction system accompanied by Marangoni instability was numerically simulated, and the actual mass transfer states of droplets were photographed using schlieren imaging technology. The results reveal that: suspended droplets may have mass transfer states such as diffusion layer, natural convection, jet and turbulence, and the Marangoni instability causes the droplets to jet solute intermittently. Compared to droplets with constant surface tension, the Marangoni effect increases the mass transfer rate during droplet formation, and the Marangoni stress generates Marangoni convection at the interface, whose mutual annexation with the internal circulation leads to droplet oscillations. The Marangoni effect also causes pulsations in droplet vorticity, increasing the solute concentration exacerbates the vortex disorder, while increasing the injection rate may suppress the pulsations, which are physically dependent on the relative advantage of droplet internal circulation over Marangoni convection. [ABSTRACT FROM AUTHOR]

• Pretreatment combined algorithms combining multiple mathematical transformations and dimensionality reduction algorithms to comprehensively process raw spectral data. • The advantage of this method is high accuracy". • A method for selecting the optimal Pretreatment combined algorithm is proposed and can accurately predict the accuracy of skarn-type iron ore. Iron ore grade determination is a key step in mining production, and its efficiency has a significant impact on mining efficiency and profitability. At present, the most commonly used method for ore grade determination is chemical analysis, which not only is expensive but also has a long assay cycle and lag effect relative to the ore allocation process and cannot effectively reduce the loss depletion rate of ore mining. Therefore, in situ iron ore grade data determination technology based on visible and near-infrared hyperspectral data analysis is an effective way to solve the above problems, but the poor quality of raw hyperspectral data and low accuracy of the ore grade inversion model are still one of the bottlenecks in the application of this technology. In this paper, 225 ore samples were collected from Hongling skarn-type iron ore in Chifeng, Inner Mongolia Autonomous Region, China. The visible and near-infrared hyperspectral data of the sample set and the grade data obtained from chemical analysis were used as data sources. The raw spectral data were first smoothed, and then the smoothed spectral data were processed using two algorithms, continuum removal (CR) and standard normal variate transform (SNV). Then, two dimensionality reduction algorithms, principal component analysis (PCA) and genetic algorithm (GA), were used to reduce the dimensionality of the spectral data before and after preprocessing, and the data sources were obtained after the four different preprocessing combination algorithms were processed. Finally, several quantitative inversion models were established based on the random forest algorithm and the backpropagation neural network (BPNN) algorithm. The stability, accuracy and credibility of the models were evaluated by four metrics: the coefficient of determination (R2), root mean square error (RMSE), residual prediction deviation(RPD) and mean relative error (MRE). The results showed that the quantitative inversion model (SNV-PCA-BPNN) established based on the BP neural network algorithm using the data processed by SNV and PCA for dimensionality reduction was the best, with an R2 of 0.99, an RMSE of 0.0048, an MRE of 1.10% and a RPD of 37.70, providing an effective method for the high-precision inversion of iron ore grades. [ABSTRACT FROM AUTHOR]