Spatial autocorrelation and driving factors of carbon emission density of crop production in China.

Mitigating carbon emissions from crop production is essential for addressing global warming. At a macro-level, existing studies have often relied on the calculation of carbon emission intensity of crop production to understand comparable carbon effects between regions. However, this approach obscures the differences in crop planting scale and natural attributes across regions, leaving room for improvement in the methods and scope of analysis. To extend the existing research, we proposed an idea for calculating the carbon emission density of crop production based on planting area. Additionally, we developed an analytical framework for driving factors of carbon emission density of crop production from a spatial interaction perspective. The provincial carbon emission density of crop production in mainland China between 2000 and 2020 was calculated, and spatial econometric models were utilized to investigate the spatial autocorrelation and driving factors. The results indicate that the national average carbon emission density of crop production was 1.462 t/hm2 annually. Over 21 years, the carbon emission density of agricultural materials, rice cultivation, soil management, and straw burning evolved from 0.384 to 0.470 t/hm2, 0.409 to 0.367 t/hm2, 0.171 to 0.169 t/hm2, and 0.317 to 0.448 t/hm2, respectively. The global Moran's index indicated a positive spatial autocorrelation of carbon emission density of crop production and the subdivided carbon sources among provinces. Regarding direct effects, an increase in the proportion of paddy fields in cropland composition and irrigation efficiency would significantly promote the carbon emission density, while factors such as cropland area, multiple cropping, agricultural personnel numbers, departmental proportion, and disaster degree would decrease the local carbon emission density. Certain factors, such as cropland area and agricultural disasters, had a spatial spillover effect on carbon emission density between provinces. The study suggests harnessing key drivers and spatial spillover effects to achieve regional low-carbon crop production.

Electrochemical sensor propelled by exonuclease III for highly efficient microRNA-155 detection.

MicroRNA-155 is highly expressed in tumor cells such as lung cancer, liver cancer and lymphoma. As such, it is increasingly used for the early diagnosis and monitoring of cancer diseases. Herein, we designed an electrochemical sensor propelled by exonuclease III, which is coupled with multiple signal amplification strategies for highly efficient microRNA-155 detection. In the presence of miRNA-155, a DNA hairpin probe with exposed bases at both ends was found to form a flat end, which can be hydrolyzed by exonuclease III. The produced single-stranded DNA enters the next cycle for further cleavage to produce another single-stranded DNA. The end product can trigger a hybridization chain reaction on the electrode surface, which is used for electrochemical detection with methylene blue as an electrochemical signaling indicator. Under optimal reaction conditions, there is good linear correlation between the logarithm of the target concentration and the current signal, with the concentration ranging from 0.1 fM to 0.1 nM. The detection limit is as low as 0.035 fM. Overall, the strategy for miRNA detection offers good prospects for early cancer screening.

In-situ Formation of Amorphous Co-Al-P Layer on CoAl Layered Double Hydroxide Nanoarray as Neutral Electrocatalysts for Hydrogen Evolution Reaction.

Exploration of high-efficiency and inexpensive electrode catalysts is of vital importance for the hydrogen evolution reaction (HER). In this research, an amorphous Co-Al-P layer was constructed on the surface of CoAl layered double hydroxide (CoAl-LDH) via an in-situ wet phosphidation strategy. The core-shell CoAl-LDH@Co-Al-P on Ti mesh (CoAl-LDH@Co-Al-P/TM) as an active HER electrocatalyst demands an overpotential of 150 mV to achieve a current density of 10 mA cm-2 at neutral pH. Moreover, CoAl-LDH@Co-Al-P/TM also exhibits good electrochemical stability and a superior Faradic efficiency of nearly 100%.

Biomineralization: An Opportunity and Challenge of Nanoparticle Drug Delivery Systems for Cancer Therapy.

Biomineralization is a common process in organisms to produce hard biomaterials by combining inorganic ions with biomacromolecules. Multifunctional nanoplatforms are developed based on the mechanism of biomineralization in many biomedical applications. In the past few years, biomineralization-based nanoparticle drug delivery systems for the cancer treatment have gained a lot of research attention due to the advantages including simple preparation, good biocompatibility, degradability, easy modification, versatility, and targeting. In this review, the research trends of biomineralization-based nanoparticle drug delivery systems and their applications in cancer therapy are summarized. This work aims to promote future researches on cancer therapy based on biomineralization. Rational design of nanoparticle drug delivery systems can overcome the bottleneck in the clinical transformation of nanomaterials. At the same time, biomineralization has also provided new research ideas for cancer treatment, i.e., targeted therapy, which has significantly better performance.

FeCoNi Sulfides Derived From In situ Sulfurization of Precursor Oxides as Oxygen Evolution Reaction Catalyst.

It is highly promising to design and develop efficient and economical electrocatalysts for oxygen evolution reaction (OER) in alkaline solution. In this work, we prepare FeCoNi sulfide composites (including FeS, Co3S4, and Ni3S4) derived from in situ sulfurization of precursor oxides on carbon cloth (CC), which are used to become an OER catalyst. Such catalyst shows excellent OER performance, low overpotential, small Tafel slope, and high electrochemical stability, and it is a promising electrocatalyst for OER in alkaline media.

Intracellular dark-field imaging of ATP and photothermal therapy using a colorimetric assay based on gold nanoparticle aggregation via tetrazine/trans-cyclooctene cycloaddition.

In this study, we developed a colorimetric ATP assay based on the ATP-induced aggregation of Au nanoparticles (AuNPs). This aggregation modified the local surface plasmon resonance (LSPR) of the AuNPs, which was used to detect and localize ATP in cells via dark-field imaging. The AuNP aggregation process involved the reaction of two types of functionalized AuNPs with each other: tetrazine-modified AuNPs (Au3-N4) and asymmetrically functionalized trans-cyclooctene-modified AuNPs (Au1-(E)-cyclooctene). This cycloaddition reaction occurs without the need for a catalyst such as the Cu ions that are used in the "click" reactions often employed in assays of this type. Initially, we asymmetrically functionalized both types of AuNPs and let them dimerize, which permitted us to explore the resulting wavelength shift in the LSPR of the AuNPs. Then, to facilitate the specific recognition of ATP, a designed DNA (DNA1) containing an ATP aptamer sequence was attached to carboxyl polystyrene microbeads (MBs). After attaching a different DNA (DNA2, which hybridizes with DNA1) to Au1-(E)-cyclooctene, the assay probe MB/DNA1/DNA2/Au1-(E)-cyclooctene (MB/Au1) was generated. While bound to MB/DNA1, the DNA2/Au1-(E)-cyclooctene cannot react with Au3-N4 due to steric hindrance from the MB. However, in the presence of ATP, the probe MB/Au1 dissociates, and the resulting free DNA2/Au1-(E)-cyclooctene can then react with the Au3-N4, leading to the formation of AuNP aggregates. Dark-field microscopy (DFM) images showed that the LSPR of the AuNPs shifted from the green region (AuNP monomers) to the orange-red region (AuNP aggregates) in the presence of intracellular ATP. Moreover, the AuNP aggregates were found to exhibit significant photothermal effects under 808-nm laser irradiation. Upon introducing the probe MB/Au1 and Au3-N4 into HeLa cells in vitro and in vivo, and then irradiating the cells with a 808-nm NIR laser, the resulting AuNP aggregates showed promising photothermal cancer therapy performance. This assay therefore has the potential to be widely used for the identification and determination of nanoparticles in biological DFM and in tumor theranostics. Graphical abstract.

Nanopore-Based Strategy for Sensing of Copper(II) Ion and Real-Time Monitoring of a Click Reaction.

A straightforward yet efficient, nanopore-based strategy that enables the sensitive detection of copper(II) ion (Cu2+) and real-time monitoring of a click reaction is provided. Two single-stranded DNAs (ssDNAs) are designed to act as the preprobes, one being modified with an azide and the other an alkyne. The presence of Cu2+ induces the ligation of two ssDNAs via click reaction, leading to the formation of a forked DNA which can quantitatively generate characteristic current signatures when interacts with α-hemolysin (α-HL) nanopore. The assay facilitates a highly selective and sensitive measurement of Cu2+ without the need for labels or signal amplification. More importantly, this nanopore platform exhibits excellent performance in real-time monitoring of a copper(I) ion (Cu+)-catalyzed click reaction at the single-molecule level, by recording the current signals of the forked DNA generated by click chemistry. The proposed strategy is believed to play an important role in both nanopore sensing and characterization of chemistry reactions, especially coupling reactions.

A 3D porous Ni-CeO2 nanosheet array as a highly efficient electrocatalyst toward alkaline hydrogen evolution.

In this Communication, we report a 3D porous Ni-CeO2 nanosheet array supported on a Ti mesh (Ni-CeO2/TM) as an excellent electrocatalyst toward the alkaline hydrogen evolution reaction. To afford a current density of 10 mA cm-2, Ni-CeO2/TM requires an overpotential as low as 67 mV, 77 mV lower than that of Ni/TM. Furthermore, the electrocatalyst shows good electrochemical durability with nearly 100% faradaic efficiency.

Efficient alkaline hydrogen evolution electrocatalysis enabled by an amorphous Co-Mo-B film.

An amorphous Co-Mo-B film on a Ti mesh (Co-Mo-B/Ti) is fabricated via one-step electrodeposition exhibiting a dramatically enhanced hydrogen evolution reaction (HER) performance in alkaline media. To attain a current density of 20 mA cm-2, such Co-Mo-B/Ti demands only an overpotential of 110 mV, 190 mV lower than that of the counterpart Co-B/Ti, with strong electrochemical durability to maintain its catalytic activity for at least 32 h.

Label-free detection of microRNA based on coupling multiple isothermal amplification techniques.

MicroRNA (miRNA) was a promising class of cancer biomarkers. Here we developed a label-free method for sensitive measurement of let-7d miRNA based on multiple amplification techniques. The primer will bind to the duplex strand DNA that was formed by stem-loop template and target let-7d to initiate strand displacement amplification (SDA) in tandem. The released single strand DNA will be a primer to bind the circular template to initiate rolling circle amplification (RCA). The products based on multiple amplifications will be detected by a standard fluorimeter with N-methyl mesoporphyrin IX (NMM) as the fluorescent indicator. The proposed method exhibited excellent selectivity and high sensitivity with a detection limit of as low as 1.5 × 10-13 M. Moreover, this methodology was used for the determination of biomolecules in real serum samples with satisfying results.