Glucose-derived solid acids and their stability enhancement for upgrading biodiesel via esterification

Utilization of biomass-derived materials or chemicals plays a significant role in reducing the dependence of unsustainable resources of petroleum and coal. A series of sulfonated glucose-derived solid acids(SGSAs) were developed in this study through a one-step method. These catalysts were characterized by XRD, FT-IR, SEM,and BET to determine their physiochemical properties, and their acid content was measured by acid–base titration. The catalytic performances of SGSA catalysts were evaluated in two esterification reactions: propionic acid or oleic acid with methanol(a typical reaction to upgrade biodiesel). Conversion of oleic acid and selectivity of methyl oleate can reach as high as 93.3% and 94.7% respectively over SGSA-6, which has the highest -SO3 H density. Moreover, regeneration of spent catalysts by sulfuric acid solution can significantly enhance their stability and reusability.

Writing ink-promoted synthesis of electrodes with high energy storage performance: A review

As the low-cost commercial product, writing inks(pen ink and Chinese ink) have attracted great attention to fabricate electrochemical electrodes for supercapacitors(SCs) and batteries. Due to the conductive nature deriving from graphitic carbon nanoparticles in ink and strong adhesion, ink can be easily coated onto support to enhance the conductivity, form a porous layer facilitating electrolyte ion diffusion, increase the specific surface area and function as binder and dispersant for other active materials. In this review,the beneficial features of pen ink and Chinese ink are summarized and how these features favor the electrochemical performance is discussed in details. And then, ways to coat ink onto support are described,giving a clear understanding of recent process in this area. Finally, the current challenges and outlook of ink-based electrode are discussed, aiming to offer some basic knowledge and promote wide application and future study of pen ink and Chinese ink in electrochemistry.

Constructing a Z-scheme Fe-MOF-based heterostructure for visible-light-driven oxidation of aromatic alcohol in ambient air

Photocatalytic oxidation of aromatic alcohol into aromatic aldehyde using O_(2)has received huge atten-tion,while the reaction that occurred in ambient air is rarely studied but follows the green-chemistry principles.Herein,spindle-shaped MIL-53(Fe)-NH_(2)@ZnIn_(2)S_(4)photocatalysts with a Z-scheme heterostruc-ture were facilely developed for photocatalytic oxidation of aromatic alcohol in air under visible light.The benzyl alcohol conversion can be notably enhanced to 73%over the optimal MIL-53-NH_(2)@ZnIn_(2)S_(4)sample with a benzaldehyde production rate of 1825μmol g^(-1)h^(-1).However,in the O_(2)atmosphere,the benzyl alcohol conversion is only 56%,indicating that O_(2)is not required and has an adverse effect on the reaction.The hierarchical structure and Z-scheme heterojunction of MIL-53-NH_(2)@ZnIn_(2)S_(4)impart an efficient separation and strong redox abilities of photo-induced electrons and holes,which are respon-sible for the impressive photocatalytic performance.This study could motivate the ingenious design of Z-scheme heterostructures for green organic conversion based on MOFs.

Linear regression under model uncertainty

We reexamine the classical linear regression model when it is subject to two types of uncertainty:(i)some covariates are either missing or completely inaccessible,and(ii)the variance of the measurement error is undetermined and changing according to a mechanism unknown to the statistician.By following the recent theory of sublinear expectation,we propose to characterize such mean and variance uncertainty in the response variable by two specific nonlinear random variables,which encompass an infinite family of probability distributions for the response variable in the sense of(linear)classical probability theory.The approach enables a family of estimators under various loss functions for the regression parameter and the parameters related to model uncertainty.The consistency of the estimators is established under mild conditions in the data generation process.Three applications are introduced to assess the quality of the approach including a forecasting model for the S&P Index.

Mechanical design,modeling,and identification for a novel antagonistic variable stiffness dexterous finger

This study traces the development of dexterous hand research and proposes a novel antagonistic variable stiffness dexterous finger mechanism to improve the safety of dexterous hand in unpredictable environments,such as unstructured or man-made operational errors through comprehensive consideration of cost,accuracy,manufacturing,and application.Based on the concept of mechanical passive compliance,which is widely implemented in robots for interactions,a finger is dedicated to improving mechanical robustness.The finger mechanism not only achieves passive compliance against physical impacts,but also implements the variable stiffness actuator principle in a compact finger without adding supererogatory actuators.It achieves finger stiffness adjustability according to the biologically inspired stiffness variation principle of discarding some mobilities to adjust stiffness.The mechanical design of the finger and its stiffness adjusting methods are elaborated.The stiffness characteristics of the finger joint and the actuation unit are analyzed.Experimental results of the finger joint stiffness identification and finger impact tests under different finger stiffness presets are provided to verify the validity of the model.Fingers have been experimentally proven to be robust against physical impacts.Moreover,the experimental part verifies that fingers have good power,grasping,and manipulation performance.