Application of advanced nuclear analytical techniques for the electrocatalyst's characterization: Paving the path for mechanistic investigations

As the application of electrocatalyst continues to expand, envisaging the hidden mechanisms occurring at various length scale affecting the catalytic efficiency became important. To enhance the stability of electrocatalyst and reduce the cost, it is of paramount importance to reveal the active site's dynamics (using in situ techniques for getting the real-time information) which directly affect the reactions such as oxygen evolution reaction, hydrogen evolution reaction, and so on. Since such reactions are crucial for many engineering and scientific applications, in situ characterization techniques are required, which could capture such reactions happening at a different length and time scale. This article analyzes the recent progress made in the field of electrocatalyst's characterization using in situ neutron techniques. The article also paves the future path and has delineated the future challenges involved in multiscale correlative techniques (e.g., neutron techniques in the combination of synchrotron or microscopic techniques) used for getting the multiscale (atomic to micrometer range) mechanistic information about the electrocatalyst's working and degradation.     

Toward efficient interactions of bubbles and coal particles induced by stable cavitation bubbles under 600 kHz ultrasonic standing waves

The interactions of bubbles and coal particles in 600 kHz ultrasonic standing waves (USW) field has been investigated. A high-speed camera was employed to record the phenomena occurred under the USW treatment. The formation and behaviors of cavitation bubbles were analyzed. Under the driving of these cavitation bubbles, whose size is from several microns to dozens of microns, coal particles were aggregated and then attracted by large bubbles due to the acoustic radiation forces. The results of USW-assisted flotation show a significant improvement in recoveries at 600 kHz, which indicates that the interactions of bubbles and particles in the USW field are more efficient than that in the conventional gravitational field. Furthermore, the sound pressure distribution of the USW was measured and predicted by a hydrophone. The analysis of gravity and buoyancy, primary and secondary Bjerknes forces shows that bubble-laden particles can be attracted by the rising bubbles under large acoustic forces. This study highlights the potential for USW technology to achieve efficient bubble-particle interactions in flotation.     

Intensification of delignification of Tectona grandis saw dust as sustainable biomass using acoustic cavitational devices

Delignification of sawdust was studied using ultrasound assisted alkali peroxide approach using longitudinal horn for the first time and the efficacy compared with more commonly used configurations of ultrasonic reactors. Comparison with the conventional approach based on stirring has also been presented to establish the process intensification benefits. Effect of different operating parameters such as sodium carbonate concentration (0.1, 0.15, 0.2, 0.25 M), hydrogen peroxide concentration (0.2, 0.4, 0.6, 0.8, 1 M) and biomass loading (2, 4, 6, 8, 10 wt%), on the efficacy of lignin extraction has been investigated for different ultrasonic reactors. The optimum conditions for probe type ultrasonic horn were established as 150 W, 50% duty cycle and 80% amplitude with optimum process conditions as Na₂CO₃ concentration as 0.2 M, H₂O₂ concentration as 1 M, biomass loading of 10 wt% and operating time of 70 min. Longitudinal horn resulted in best efficacy (both in terms of yield and energy requirements) followed by ultrasonic horn and ultrasonic bath whereas the conventional approach was least effective. The obtained lignin was also analyzed using different characterization techniques. The presence of peaks at wavelength range of 875–817, 1123–1110, and at 1599 cm⁻¹ for the extracted sample confirmed the presence of lignin. Increase in the crystallinity index of the processed sample (maximum for longitudinal horn) also confirmed the lignin removal as lignin is amorphous in nature. Overall it has been concluded that ultrasound can be effectively used for delignification with longitudinal horn as best configuration.     

油-气-水三相流超声传感器持气率测量*

为探索油-气-水三相流持气率测量难题,该文开展了脉冲透射式超声传感器持气率测量动态实验研究。首先,利用超声传感器与光纤传感器组合,测取了油-气-水三相流中段塞流、混状流、泡状流的响应信号;其次,提取了超声脉冲信号的最大值序列来反映不同流型时超声传感器响应特性,同时,借助双头光纤传感器与相关测速法,计算得到了流体中气泡弦长序列;最后,结合流型与泡径信息,利用超声传感器测量了不同流型下持气率,并分析了不同流型持气率预测的误差来源,为其他油-气-水三相流持气率测量传感器设计提供了借鉴。     

From Minutes to Years: Predicting Organotrifluoroborate Solvolysis Rates

Organotrifluoroborates solvolyze in water at rates that vary over five orders of magnitude. The negative logarithm of the solvolytic rate constant, pk_(B?F), correlates exceptionally well with the pK_a of the analogous carboxylic acid (R²=0.984). This unforeseen correlation may be of predictive value for several applications including Suzuki–Miyaura cross‐coupling reactions and the design of ¹⁸F‐organotrifluoroborate radioprosthetic groups.     

超声筛查早期诊断婴儿发育性髋关节异常的临床管理

目的 了解鄞州区0~6月龄婴儿发育性髋关节异常（developmental dysplasia of hip,DDH）的流行病学特征，探讨DDH 的临床管理模式。方法 由鄞州区妇幼保健机构社区医师和鄞州区第二医院围生医生共同负责完成DDH 的临床初筛工作，可疑或异常者转儿科进一步检查，并予B 超筛查，对不同人群分别进行早期干预、复查、随访及骨盆正位X 线片检查，必要时转小儿骨科治疗。结果 2012 年5 月至2013 年5 月，共6 890 例0~6月龄婴儿进行髋关节B 超筛查，初筛阳性率5.73%（395/6 890），复查阳性率0.59%（34/5729）；月龄越小筛查阳性率越高，差异有统计学意义（P＜0.05）。新生儿及1~3月龄婴儿初筛阳性率高，但复查阳性率明显降低，差异有统计学意义（P＜0.05）；4~6月龄婴儿初筛及复查阳性率差异无统计学意义（P ＞0.05）。结论 鄞州区采取的社区门诊检查- 区医院儿科复查-B 超筛查及转诊治疗的管理模式，可作为基层推进DDH 的早发现和早治疗的有效手段。     

Experimental Evaluation of Undersampling Schemes for Electron Tomography of Nanoparticles

One of the emerging challenges in the field of 3D characterization of nanoparticles by electron tomography is to avoid degradation and deformation of the samples during the acquisition of a tilt series. In order to reduce the required electron dose, various undersampling approaches have been proposed. These methods include lowering the number of 2D projection images, reducing the probe current during the acquisition, and scanning a smaller number of pixels in the 2D images. A comparison is made between these approaches based on tilt series acquired for a gold nanoparticle.     

Fabrication and characterization of cellulose nanoparticles from maize stalk pith via ultrasonic-mediated cationic etherification

In this study, parenchyma cellulose, which was extracted from maize stalk pith as an abundant source of agricultural residues, was applied for preparing cellulose nanoparticles (CNPs) via an ultrasound-assisted etherification and a subsequent sonication process. The ultrasonic-assisted treatment greatly improved the modification of the pith cellulose with glycidyltrimethylammonium chloride, leading to a partial increase in the dissolubility of the as-obtained product and thus disintegration of sheet-like cellulose into nanoparticles. While the formation of CNPs by ultrasonication was largely dependent on the cellulose consistency in the cationic-modified system. Under the condition of 25% cellulose consistency, the longer sono-treated duration yielded a more stable and dispersible suspension of CNP due to its higher zeta potential. Degree of substitution and FT-IR analyses indicated that quaternary ammonium salts were grafted onto hydroxyl groups of cellulose chain. SEM and TEM images exhibited the CNP to have spherical morphology with an average dimeter from 15 to 55 nm. XRD investigation revealed that CNPs consisted mainly of a crystalline cellulose Ι structure, and they had a lower crystallinity than the starting cellulose. Moreover, thermogravimetric results illustrated the thermal resistance of the CNPs was lower than the pith cellulose. The optimal CNP with highly cationic charges, good stability and acceptable thermostability might be considered as one of the alternatively renewable reinforcement additives for nanocomposite production.     

Influence of ultrasound on the functional characteristics of indigenous varieties of mango (Mangifera indica L.)

The present study was conducted to evaluate the effect of ultrasonic (US) treatment on chemical characteristics and antioxidant potential of pulps obtained from eight mango varieties indigenous to Pakistan. There was a significant (p < 0.05) effect of varieties and US treatment on chemical characteristics i.e. pH, acidity, TSS, vitamin C contents, total sugars (%), reducing sugars (%) and non-reducing sugars (%). Microstructure evaluation of pulp from all mango varieties showed deshaped middle lamella and cell wall of cells after 8 min of US treatment. At 4 min of US treatment as per shaped cell wall and middle lamella, the chemical characteristics and antioxidant potential were higher. The total phenolics (TP), flavonoids (TF) and total antioxidant activity (TAA) of pulp from most varieties increased significantly (p < 0.05) after US treatment for 4 min but decreased successively after each treatment i.e. 8 and 12 min. The maximum value (314.17 μg AAE/mL pulp) of DPPH was shown by pulp from Dosehri and the minimum (158.67 μg AAE/mL pulp) was found in pulp from Langra before US treatment. The DPPH values of pulp from most of the varieties increased significantly (p < 0.05) after US treatment for 4 min but decreased successively after each treatment but pulp from Langra showed increasing trend after 8 min of US treatment which decreased after 12 min of treatment. The total anthocyanin (TA) values of pulp from Chaunsa, Dosehri, Sindhri, Gulab Khas and Langra increased abruptly after US treatment for 4 min but decreased successively after subsequent treatment. The pulp from Desi, Anwar Ratol, Gulab Khas and Langra showed an abrupt decrease in TA after 8 min of US treatment. An increasing trend of values of total carotenoids (TC) was shown by pulp from all mango varieties after 4 min of US treatment but decreasing trend was observed with subsequent increase in time of US treatment.     

Two-dimensional optical coherence tomography for real-time structural dynamical characterization

We present a two-dimensional optical coherence vibration tomography (2DOCVT) system with an ultra-precision displacement resolution of ~0.1 nm that is capable of in site real-time absolute displacement measurement of structural line vibrations. Experimental results of sinusoidal, sweep and impulse vibrations were reported. The key figures of merit such as the 2DOCVT system could obtain fast line vibration measurement without scanning and it also could be used to capture structural modal parameters in one single impulse excitation measurement without any vibration excitation input information, making it attractive for the application in low-frequency vibration measurement and response-only modal analysis.