Fork PCR: a universal and efficient genome-walking tool

The reported genome-walking methods still suffer from some deficiencies, such as cumbersome experimental steps, short target amplicon, or deep background. Here, a simple and practical fork PCR was proposed for genome-walking. The fork PCR employs a fork primer set of three random oligomers to implement walking task. In primary fork PCR, the low-stringency amplification cycle mediates the random binding of primary fork primer to some places on genome, producing a batch of single-stranded DNAs. In the subsequent high-stringency amplification, the target single-strand is processed into double-strand by the site-specific primer, but a non-target single-stranded DNA cannot be processed by any primer. As a result, only the target DNA can be exponentially amplified in the remaining high-stringency cycles. Secondary/tertiary nested fork PCR(s) further magnifies the amplification difference between the both DNAs by selectively enriching target DNA. The applicability of fork PCR was validated by walking several gene loci. The fork PCR could be a perspective substitution for the existing genome-walking schemes

The dynamic evolution of multipoint interplanetary coronal mass ejections observed with BepiColombo, Tianwen-1, and MAVEN

We present two multipoint interplanetary coronal mass ejections (ICMEs) detected by the Tianwen-1 and Mars Atmosphere and Volatile Evolution spacecraft at Mars and the BepiColombo (0.56 au ∼0.67 au) upstream of Mars from 2021 December 5 to 31. This is the first time that BepiColombo is used as an upstream solar wind monitor ahead of Mars and that Tianwen-1 is used to investigate the magnetic field characteristics of ICMEs at Mars. The Heliospheric Upwind Extrapolation time model was used to connect the multiple in situ observations and the coronagraph observations from STEREO/SECCHI and SOHO/LASCO. The first fast coronal mass ejection event (∼761.2 km s−1), which erupted on December 4, impacted Mars centrally and grazed BepiColombo by its western flank. The ambient slow solar wind decelerated the west flank of the ICME, implying that the ICME event was significantly distorted by the solar wind structure. The second slow ICME event (∼390.7 km s−1) underwent an acceleration from its eruption to a distance within 0.69 au and then traveled with the constant velocity of the ambient solar wind. These findings highlight the importance of background solar wind in determining the interplanetary evolution and global morphology of ICMEs up to Mars distance. Observations from multiple locations are invaluable for space weather studies at Mars and merit more exploration in the future

Evaluation of the ‘Local Climate Zone’ classification scheme in Singapore

Bachelor'sBachelor of Environmental Studies (Honours

High-throughput characterization methods for lithium batteries

The development of high-performance lithium ion batteries requires the discovery of new materials and the optimization of key components. By contrast with traditional one-by-one method, high-throughput method can synthesize and characterize a large number of compositionally varying samples, which is able to accelerate the pace of discovery, development and optimization process of materials. Because of rapid progress in thin film and automatic control technologies, thousands of compounds with different compositions could be synthesized rapidly right now, even in a single experiment. However, the lack of rapid or combinatorial characterization technologies to match with high-throughput synthesis methods, limit the application of high-throughput technology. Here, we review a series of representative high-throughput characterization methods used in lithium batteries, including high-throughput structural and electrochemical characterization methods and rapid measuring technologies based on synchrotron light sources

A Novel Scheme of Power Equalization and Power Management in WDM All-Optical Networks

In this letter, a novel scheme for module implementation of power equalization in wavelength-division-multiplexed (WDM) all-optical networks is proposed. The power equalization and the power amplification are united into one module and the node isolation principle is applied. The simulation shows that ours is more explicit and efficient than the traditional schemes. The larger number of cascaded nodes is permitted and the system performance (signal-to-noise ratio) can be kept without deterioration. Consequently, a feasible novel solution to power management in WDM all-optical networks is presented

Reaction mechanisms of NASICON-type Na4MnV(PO4)3/C as a cathode for sodium-ion batteries

NASCION-type Na4MnV(PO4)3/C was synthesized through a sol–gel method. Two Na+ ions can reversibly (de)intercalation from/into the unit structure, with a reversible capacity of 106.7 mAh/g. The charge–discharge curves show a voltage slope at 3.4 V, and a plateau at 3.6 V. To elucidate the sodium storage mechanisms, the structure evolution and electron transfer are demonstrated using in-situ X-ray diffraction and ex-situ X-ray absorption spectroscopy. It is found that at different stage of the electrochemical process, it undergoes different phase reaction process with different redox couples. A single-phase reaction occurs when the first sodium-ion extracted from Na4MnV(PO4)3 with a V3+/V4+ redox, while a two-phase reaction takes place when the second sodium-ion extracted with a Mn2+/Mn3+ redox. Galvanostatic intermittent titration technique, GITT, indicates the single-phase reaction process shows a faster kinetic compared to the two-phase reaction process. These findings between the kinetics, chemical and structural evolution provide new insight into the sodium storage mechanisms of NASICON-type cathode, and further the understanding of other materials for sodium-ion batteries