Enhancing antibody detection sensitivity in lateral flow immunoassays using endospores of Bacillus subtilis as signal amplifiers.

Antibody detection is the critical first step for tracking the spread of many diseases including COVID-19. Lateral flow immunoassay (LFIA) is the most commonly used method for rapid antibody detection because it is easy-to-use and inexpensive. However, LFIA has limited sensitivity when gold nanoparticles (AuNPs) are used as the signals. In this study, the endospores of Bacillus subtilis were used in combination with AuNP in a LFIA to detect antibodies. The endospores serve as a signal amplifier. The detection limit was about 10-8 M for anti-beta galactosidase antibody detection whereas the detection limit of conventional LFIA is about 10-6 M. Furthermore, the proposed methods have no additional user steps compared with the traditional LFIA. This method, therefore, improved the sensitivity 100-fold without compromising any advantages of LFIA. We believe that the proposed method will be useful for detection of antibodies against HIV, Zika virus, SARS-CoV-2, and so on.

Towards understanding the cutting temperature in ultrasonic vibration-assisted drilling based on the dynamic contact characteristics between the cutting edge and workpiece.

Compared with conventional drilling (CD), ultrasonic vibration-assisted drilling(UVAD) is experimentally proven a promising method to reduce the cutting temperature. But sometimes cutting temperature also becomes higher in UVAD than in CD. To further make clear the cutting temperature mechanisms in UVAD, this study aims to study the effect of tool's ultrasonic vibration on the cutting heat generation and heat dissipation at a relatively micro level. Firstly, drilling experiments are designed to explore the variations of cutting heat under different ultrasonic vibrations. Then, to analyze the influence of ultrasonic vibration on the cutting heat theoretically, a kinematic model is developed to describe the dynamic contact between the cutting edge and workpiece in UVAD. Besides, a cutting heat analysis model based on the contact characteristics in UVAD is proposed to study and compare the variations of cutting heat generation. The effect of ultrasonic vibration on the cutting heat generation, heat dispassion, and the resultant cutting temperature under different machining in UVAD conditions are discussed. It is indicated from the theoretical analysis that more cutting heat tends to be produced due to the significantly increased sliding velocity on the cutting edge-workpiece interface when the ultrasonic vibration is applied. The analysis agrees with the experimental results that the cutting temperature in dry UVAD is higher than in dry CD. But on the other hand, ultrasonic vibration can also improve the lubrication and cooling effect under appropriate machining conditions, which is beneficial to the reduction in cutting temperature. The investigation shows the multifaceted influences of ultrasonic vibration on the cutting temperature in the drilling process in detail, which provides a reference for UVAD parameter optimization.

The complete mitochondrial genome of Hylarana latouchii (Anura: Ranidae) and its phylogenetic analysis.

We reported the complete mitochondrial genome (mitogenome) of broad-folded frog (Hylarana latouchii). This mitogenome is 17,007 bp in size and consists of 13 protein-coding genes, 22 transfer RNAs, two ribosomal RNAs, and one non-coding sequence (D-loop). The total composition was 58.54% A + T and 41.46% G + C (T: 29.31%, C: 27.33%, A: 29.23%, and G: 14.13%). The phylogenetic analysis revealed that H. latouchii formed a clade with other two species of genus Hylarana. This mitogenomic sequence of H. latouchii provides useful data to study its population genetics and phylogeography.