An improved CRISPR and CRISPR interference (CRISPRi) toolkit for engineering the model methanogenic archaeon Methanococcus maripaludis.

BACKGROUND: The type II based CRISPR-Cas system remains restrictedly utilized in archaea, a featured domain of life that ranks parallelly with Bacteria and Eukaryotes. Methanococcus maripaludis, known for rapid growth and genetic tractability, serves as an exemplary model for studying archaeal biology and exploring CO2-based biotechnological applications. However, tools for controlled gene regulation remain deficient and CRISPR-Cas tools still need improved in this archaeon, limiting its application as an archaeal model cellular factory. RESULTS: This study not only improved the CRISPR-Cas9 system for optimizing multiplex genome editing and CRISPR plasmid construction efficiencies but also pioneered an effective CRISPR interference (CRISPRi) system for controlled gene regulation in M. maripaludis. We developed two novel strategies for balanced expression of multiple sgRNAs, facilitating efficient multiplex genome editing. We also engineered a strain expressing Cas9 genomically, which simplified the CRISPR plasmid construction and facilitated more efficient genome modifications, including markerless and scarless gene knock-in. Importantly, we established a CRISPRi system using catalytic inactive dCas9, achieving up to 100-fold repression on target gene. Here, sgRNAs targeting near and downstream regions of the transcription start site and the 5'end ORF achieved the highest repression efficacy. Furthermore, we developed an inducible CRISPRi-dCas9 system based on TetR/tetO platform. This facilitated the inducible gene repression, especially for essential genes. CONCLUSIONS: Therefore, these advancements not only expand the toolkit for genetic manipulation but also bridge methodological gaps for controlled gene regulation, especially for essential genes, in M. maripaludis. The robust toolkit developed here paves the way for applying M. maripaludis as a vital model archaeal cell factory, facilitating fundamental biological studies and applied biotechnology development of archaea.

Dynamics of Electron Transfer in CdS Photocatalysts Decorated with Various Noble Metals.

To address charge recombination in photocatalysis, the prevalent approach involves the use of noble metal cocatalysts. However, the precise factors influencing this performance variability based on cocatalyst selection have remained elusive. In this study, CdS hollow spheres loaded with distinct noble metal nanoparticles (Pt, Au, and Ru) are investigated by femtosecond transient absorption (fs-TA) spectroscopy. A more pronounced internal electric field leads to the creation of a larger Schottky barrier, with the order Pt-CdS > Au-CdS > Ru-CdS. Owing to these varying Schottky barrier heights, the interface electron transfer rate (Ke ) and efficiency (ηe ) of metal-CdS in acetonitrile (ACN) exhibit the following trend: Ru-CdS > Au-CdS > Pt-CdS. However, the trends of Ke and ηe for metal-CdS in water are different (Ru-CdS > Pt-CdS > Au-CdS) due to the influence of water, leading to the consumption of photogenerated electrons and affecting the metal/CdS interface state. Although Ru-CdS displays the highest Ke and ηe , its overall photocatalytic performance, particularly in H2 production, lags behind that of Pt-CdS due to the electron backflow from Ru to CdS. This work offers a fresh perspective on the origin of performance differences and provides valuable insights for cocatalyst design and construction.

Dual-band terahertz absorber based on square ring metamaterial structure.

In this paper, a dual-band terahertz absorber based on metamaterial structure is designed, fabricated, and measured. The metal periodic array is located on the upper surface of a silicon wafer with a metal ground plane, while the metamaterial structure is created utilizing a square metal ring with four T-shaped metal strips loaded inside of the ring. Two absorption peaks are realized at 0.715 and 1.013 THz with high Q-factors of 152.1 and 98.3, respectively, under normal TE and TM polarized incidence. A prototype of the proposed metamaterial absorber is fabricated by electron beam lithography (EBL) and electron beam evaporation (EBE) technology. Furthermore, a terahertz time-domain spectroscopy (TDS) measurement system is employed to test the absorber sample, with good measurement results obtained. This work provides a new option for the design of multi-band terahertz metamaterial absorbers.

Highly sensitive fiber-optic temperature sensor with compact hybrid interferometers enhanced by the harmonic Vernier effect.

A compact fiber-optic temperature sensor with hybrid interferometers enhanced by the harmonic Vernier effect was proposed, which realized 36.9 times sensitization of the sensing Fabry-Perot interferometer (FPI). The hybrid interferometers configuration of the sensor consists of a FPI and a Michelson interferometer. The proposed sensor is fabricated by splicing the hole-assisted suspended-core fiber (HASCF) to the multi-mode fiber fused with the single-mode fiber, and filling polydimethylsiloxane (PDMS) into the air hole of HASCF. The high thermal expansion coefficient of PDMS improves the temperature sensitivity of the FPI. The harmonic Vernier effect eliminates the limitation of the free spectral range on the magnification factor by detecting the intersection response of internal envelopes, and realizes the secondary sensitization of the traditional Vernier effect. Combing the characteristics of HASCF, PDMS, and first-order harmonic Vernier effect, the sensor exhibits a high detection sensitivity of -19.22 nm/°C. The proposed sensor provides not only a design scheme for compact fiber-optic sensors, but also a new strategy to enhance the optical Vernier effect.

Probe the nanoparticle-nucleus interaction via coarse-grained molecular model.

The present study reports on a computational model that systematically evaluates the effect of physical factors, including size, surface modification, and rigidity, on the nuclear uptake of nanoparticles (NPs). The NP-nucleus interaction is a crucial factor in biomedical applications such as drug delivery and cellular imaging. While experimental studies have provided evidence for the influence of size, shape, and surface modification on nuclear uptake, theoretical investigations on how these physical factors affect the entrance of NPs through the nuclear pore are lacking. Our results demonstrate that larger NPs require a higher amount of energy to enter the nucleus compared to smaller NPs. This highlights the importance of size as a critical factor in NP design for nuclear uptake. Additionally, surface modification of NPs can impact the nuclear uptake pathway, indicating the potential for tailored NP design for specific applications. Notably, our findings also reveal that the rigidity of NPs has a significant effect on the transport process. The interplay between physicochemical properties and nuclear pore is found to determine nuclear uptake efficiency. Taken together, our study provides new insights into the design of NPs for precise and controllable NP-nucleus interaction, with potential implications for the development of efficient and targeted drug delivery systems and imaging agents.

Verifying the Charge-Transfer Mechanism in S-Scheme Heterojunctions Using Femtosecond Transient Absorption Spectroscopy.

The S-scheme heterojunction is flourishing in photocatalysis because it concurrently realizes separated charge carriers and sufficient redox ability. Steady-state charge transfer has been confirmed by other methods. However, an essential part, the transfer dynamics in S-scheme heterojunctions, is still missing. To compensate, a series of cadmium sulfide/pyrene-alt-difluorinated benzothiadiazole heterojunctions were constructed and the photophysical processes were investigated with femtosecond transient absorption spectroscopy. Encouragingly, an interfacial charge-transfer signal was detected in the spectra of the heterojunction, which provides solid evidence for S-scheme charge transfer to complement the results from well-established methods. Furthermore, the lifetime for interfacial charge transfer was calculated to be ca. 78.6 ps. Moreover, the S-scheme heterojunction photocatalysts exhibit higher photocatalytic conversion of 1,2-diols and H2 production rates than bare cadmium sulfide.

Rapid Charge Transfer Endowed by Interfacial Ni-O Bonding in S-scheme Heterojunction for Efficient Photocatalytic H2 and Imine Production.

Cooperative coupling of H2 evolution with oxidative organic synthesis is promising in avoiding the use of sacrificial agents and producing hydrogen energy with value-added chemicals simultaneously. Nonetheless, the photocatalytic activity is obstructed by sluggish electron-hole separation and limited redox potentials. Herein, Ni-doped Zn0.2 Cd0.8 S quantum dots are chosen after screening by DFT simulation to couple with TiO2 microspheres, forming a step-scheme heterojunction. The Ni-doped configuration tunes the highly active S site for augmented H2 evolution, and the interfacial Ni-O bonds provide fast channels at the atomic level to lower the energy barrier for charge transfer. Also, DFT calculations reveal an enhanced built-in electric field in the heterojunction for superior charge migration and separation. Kinetic analysis by femtosecond transient absorption spectra demonstrates that expedited charge migration with electrons first transfer to Ni2+ and then to S sites. Therefore, the designed catalyst delivers drastically elevated H2 yield (4.55 mmol g-1 h-1 ) and N-benzylidenebenzylamine production rate (3.35 mmol g-1 h-1 ). This work provides atomic-scale insights into the coordinated modulation of active sites and built-in electric fields in step-scheme heterojunction for ameliorative photocatalytic performance.

Reversing Free-Electron Transfer of MoS2+x Cocatalyst for Optimizing Antibonding-Orbital Occupancy Enables High Photocatalytic H2 Evolution.

The interaction between a co-catalyst and photocatalyst usually induces spontaneous free-electron transfer between them, but the effect and regulation of the transfer direction on the hydrogen-adsorption energy of the active sites have not received attention. Herein, to steer the free-electron transfer in a favorable direction for weakening S-Hads bonds of sulfur-rich MoS2+x , an electron-reversal strategy is proposed for the first time. The core-shell Au@MoS2+x cocatalyst was constructed on TiO2 to optimize the antibonding-orbital occupancy. Research results reveal that the embedded Au can reverse the electron transfer to MoS2+x to generate electron-rich S(2+δ)- active sites, thus increasing the antibonding-orbital occupancy of S-Hads in the Au@MoS2+x cocatalyst. Consequently, the increase in the antibonding-orbital occupancy effectively destabilizes the H 1s-p antibonding orbital and weakens the S-Hads bond, realizing the expedited desorption of Hads to rapidly generate a lot of visible H2 bubbles. This work delves deep into the latent effect of the photocatalyst carrier on cocatalytic activity.

Semiconductor Gas Sensor for Triethylamine Detection.

With the demanding detection of unique toxic gas, semiconductor gas sensors have attracted tremendous attention due to their intriguing features, such as, high sensitivity, online detection, portability, ease of use, and low cost. Triethylamine, a typical gas of volatile organic compounds, is an important raw material for industrial development, but it is also a hazard to human health. This review presents a concise compilation of the advances in triethylamine detection based on chemiresistive sensors. Specifically, the testing system and sensing parameters are described in detail. Besides, the sensing mechanism with characterizing tactics is analyzed. The research status based on various chemiresistive sensors is also surveyed. Finally, the conclusion and challenges, as well as some perspectives toward this area, are presented.

Nano-Sized Niobium Tungsten Oxide Anode for Advanced Fast-Charge Lithium-Ion Batteries.

The further demand for electric vehicles and smart grids prompts that the comprehensive function of lithium-ion batteries (LIBs) has been improved greatly. However, due to sluggish Li+ diffusion rate, thermal runway and volume expansion, the commercial graphite as an important part of LIBs is not suitable for fast-charging. Herein, nano-sized Nb14 W3 O44 blocks are effectively synthesized as a fast-charge anode material. The nano-sized structure provides shorter Li+ diffusion pathway in the solid phase than micro-sized materials by several orders of magnitude, corresponding to accelerating the Li+ diffusion rate, which is beneficial for fast-charge characteristics. Consequently, Nb14 W3 O44 displays excellent long-term cycling life (135 mAh g-1 over 1000 cycles at 10 C) and rate capability at ultra-high current density (≈103.9 mAh g-1 , 100 C) in half-cells. In situ X-ray diffraction and Raman combined with scanning electron microscopy clearly confirms the stability of crystal and microstructure. Furthermore, the fabricated Nb14 W3 O44 ||LiFePO4 full cells exhibit a remarkable power density and demonstrate a reversible specific capacity. The pouch cell delivers long cycling life (the capacity retention is as high as 96.6% at 10 C after 5000 cycles) and high-safety performance. Therefore, nano-sized Nb14 W3 O44 could be recognized as a promising fast-charge anode toward next-generation practical LIBs.

Cu2+-imprinted optical fiber SPR sensor for intelligent recognition.

An optical fiber surface plasma resonance (SPR) sensor with MMF-TCF-MMF structure was designed to realize intelligent recognition of copper ions (Cu2+), and the selective adsorption sensitization was achieved by plating a layer of Cu2+-imprinted film on the surface of gold film excitation layer. Combining the principle of optical fiber interference and SPR, the proposed sensor realized the detection of the copper ions concentration through measuring the refractive index changes caused by ions adsorption on imprinted film. The Cu2+-imprinted optical fiber SPR sensor can realize the intelligent recognition and detection of copper ions in the complex environment and exhibits a detection sensitivity of -10.05 pm/ppm. The proposed sensor has tremendous development potential in practical application, and provides new ideas for the field of metal ions detection.

THz absorbers with an ultrahigh Q-factor empowered by the quasi-bound states in the continuum for sensing application.

The exceptional resonances excited by symmetry-protected quasi-bound states in the continuum (QBICs) have provided significant potential in high-sensitive sensing applications. Herein, we have proposed a type of metal-insulator-metal (MIM) absorbers supported by QBIC-induced resonances, and the ideal Q-factors of QBIC-induced resonances can be enhanced up to 105 in the THz regime. The coupled mode theory and the multipole scattering theory are employed to thoroughly interpret the QBIC-induced absorption mechanism. Furthermore, the refractive index sensing capacities of the as-presented absorbers have been investigated, where the maximum values of the sensing sensitivity and figure of merit (FOM) can reach up to 187 GHz per refractive index unit and 286, respectively. Therefore, it is believed that the proposed absorbers enabled by QBIC-induced resonances hold promising potential in a broad range of highly demanding sensing applications.

Terahertz spin-selective perfect absorption enabled by quasi-bound states in the continuum.

Spin-selective absorption is broadly applicable to numerous photonic devices. Here, based on a stereoscopic full metallic resonator array, a terahertz chiral metasurface with a single-layer structure is proposed and numerically demonstrated. By employing the coupled-mode theory, we demonstrate that the chiral metasurface can near-perfectly absorb one circularly polarized wave in the quasi-bound states in the continuum-induced critical coupling region but non-resonantly reflect its counterparts. Interestingly, the linewidths and handedness of the proposed chiral metasurface can be flexibly controlled by an in-plane symmetry perturbation. Our designs might offer an alternative strategy to develop chiral metasurfaces apart from conventional methods and might stimulate many potential applications for emerging terahertz technologies.

Highly sensitive terahertz sensing with 3D-printed metasurfaces empowered by a toroidal dipole.

Highly sensitive terahertz (THz) sensing with metasurfaces has attracted considerable attention recently. However, ultrahigh sensing sensitivity remains a huge challenge for practical applications. To improve the sensitivity of these devices, herein we have proposed an out-of-plane metasurface-assisted THz sensor consisting of periodically arranged bar-like meta-atoms. Benefiting from elaborate out-of-plane structures, the proposed THz sensor with high sensing sensitivity of 325 GHz/RIU can be easily fabricated via a simple three-step fabrication process, and the maximum sensing sensitivity can be ascribed to toroidal dipole resonance-enhanced THz-matter interactions. The sensing ability of the fabricated sensor is experimentally characterized by the detection of three types of analytes. It is believed that the proposed THz sensor with ultrahigh sensing sensitivity and its fabrication method might provide great potential in emerging THz sensing applications.

Preoperative vitamin D level is significantly associated with hypocalcemia after total thyroidectomy.

BACKGROUND: To evaluate the association of preoperative vitamin D levels with postoperative hypocalcaemia after total thyroidectomy. METHODS: The medical records of patients who underwent total thyroidectomy between May 2020 and January 2022 and who had a documented preoperative serum 25-hydroxyvitamin D (25-OHD) concentration were retrospectively reviewed. Vitamin D levels were categorized into four groups: <10 ng/mL (severe vitamin D deficiency), 10-20 ng/mL (vitamin D deficiency), 20-30 ng/mL (vitamin D insufficiency), and > 30 ng/mL (vitamin D sufficiency). Multivariate logistic regression was performed to analyse the association of vitamin D levels with the risk of hypocalcaemia after controlling for potential confounding factors. RESULTS: A total of 196 patients were included in this study. Of these, 47 (24.0%) had preoperative 25-OHD < 10 ng/mL, 62 (31.6%) had 25-OHD of 10-20 ng/mL, 51 (26.0%) had 25-OHD of 20-30 ng/mL and the remaining 36 (18.4%) had 25-OHD > 30 ng/mL. The incidence of postoperative hypocalcemia was highest in the group of patients with severe vitamin D deficiency (42.6% and 23.4% for postoperative laboratory and symptomatic hypocalcaemia, respectively), followed by the group with vitamin D deficiency (29.0% and 16.1%), the group with vitamin D insufficiency (19.6% and 5.9%) and the group with vitamin D sufficiency (5.6% and 2.8%). Multivariate logistic regression indicated that the odds of postoperative laboratory hypocalcaemia for patients with severe vitamin D deficiency and vitamin D deficiency were 13.20 times (95% CI: 2.69-64.79, P < 0.01) and 6.32 times (95% CI: 1.32-30.28, P = 0.02) greater than for those with vitamin D sufficiency, respectively; while the odds of symptomatic hypocalcaemia for patients with severe vitamin D deficiency was 10.18 times (95% CI: 1.14-90.86, P = 0.04) greater than for those with vitamin D sufficiency. CONCLUSION: Preoperative vitamin D deficiency (< 20 ng/mL), especially severe vitamin D deficiency (< 10 ng/mL), is an independent predictive factor of postoperative hypocalcaemia after total thyroidectomy.

Effect of Loblolly Pine (Pinus taeda L.) Hemicellulose Structure on the Properties of Hemicellulose-Polyvinyl Alcohol Composite Film.

Hemicellulose is the second most abundant natural polysaccharide and a promising feedstock for biomaterial synthesis. In the present study, the hemicellulose of loblolly pine was obtained by the alkali extraction-graded ethanol precipitation technique, and the hemicellulose-polyvinyl alcohol (hemicellulose-PVA) composite film was prepared by film casting from water. Results showed that hemicellulose with a low degree of substitution is prone to self-aggregation during film formation, while hemicellulose with high branching has better compatibility with PVA and is easier to form a homogeneous composite film. In addition, the higher molecular weight of hemicellulose facilitates the preparation of hemicellulose-PVA composite film with better mechanical properties. More residual lignin in hemicellulose results in the better UV shielding ability of the composite film. This study provides essential support for the efficient and rational utilization of hemicellulose.

Turbulence Model Comparative Study for Complex Phenomena in Supersonic Steam Ejectors with Double Choking Mode.

Scholars usually ignore the non-equilibrium condensing effects in turbulence-model comparative studies on supersonic steam ejectors. In this study, a non-equilibrium condensation model considering real physical properties was coupled respectively with seven turbulence models. They are the k-ε Standard, k-ε RNG, k-ε Realizable, k-ω Standard, k-ω SST, Transition SST, and Linear Reynolds Stress Model. Simulation results were compared with the experiment results globally and locally. The complex flow phenomena in the steam ejector captured by different models, including shock waves, choking, non-equilibrium condensation, boundary layer separation, and vortices were discussed. The reasons for the differences in simulation results were explained and compared. The relationship between ejector performance and local flow phenomena was illustrated. The novelty lies in the conclusions that consider the non-equilibrium condensing effects. Results show that the number and type of shock waves predicted by different turbulence models are different. Non-equilibrium condensation and boundary layer separation regions obtained by various turbulence models are different. Comparing the ejector performance and the complex flow phenomena with the experimental results, the k-ω SST model is proposed to simulate supersonic steam ejectors.

In situ Irradiated XPS Investigation on S-Scheme TiO2 @ZnIn2 S4 Photocatalyst for Efficient Photocatalytic CO2 Reduction.

Reasonable design of efficient hierarchical photocatalysts has gained significant attention. Herein, a step-scheme (S-scheme) core-shell TiO2 @ZnIn2 S4 heterojunction is designed for photocatalytic CO2 reduction. The optimized sample exhibits much higher CO2 photoreduction conversion rates (the sum yield of CO, CH3 OH, and CH4 ) than the blank control, i.e., ZnIn2 S4 and TiO2 . The improved photocatalytic performance can be attributed to the inhibited recombination of photogenerated charge carriers induced by S-scheme heterojunction. The improvement is also attributed to the large specific surface areas and abundant active sites. Meanwhile, S-scheme photogenerated charge transfer mechanism is testified by in situ irradiated X-ray photoelectron spectroscopy, work function calculation, and electron paramagnetic resonance measurements. This work provides an effective strategy for designing highly efficient heterojunction photocatalysts for conversion of solar fuels.

Core-Shell Structured C@SiO2 Hollow Spheres Decorated with Nickel Nanoparticles as Anode Materials for Lithium-Ion Batteries.

Silicon oxide is regarded as a promising anode material for lithium-ion batteries owing to high theoretical capacity, abundant reserve, and environmental friendliness. Large volumetric variations during the discharging/charging and intrinsically poor electrical conductivity, however, severely hinder its application. Herein, a core-shell structured composite is constructed by hollow carbon spheres and SiO2 nanosheets decorated with nickel nanoparticles (Ni-SiO2 /C HS). Hollow carbon spheres, as mesoporous cores, not only significantly facilitate the electron transfer but also prominently enhance the mechanical robustness of anode materials, which separately improves the rate performance and the cyclic durability. Besides, ultrathin SiO2 nanosheets, as hierarchical shells, provide abundant electrochemical active surface for capacity increment. Moreover, nickel nanoparticles boost the transport capacity of electrons in SiO2 nanosheets. Such a unique architecture of Ni-SiO2 /C HS guarantees an enhanced discharge capacity (712 mAh g-1 at 0.1 A g-1 ) and prolonged cyclic durability (352 mAh g-1 at 1.0 A g-1 after 500 cycles). The present work offers a possibility for silica-based anode materials in the application of next-generation lithium-ion batteries.

Mechanical modulation of multifunctional responses in three-dimensional terahertz metamaterials.

Reconfigurable metamaterials have attracted a surge of attention for their formidable capability to dynamically manipulate the electromagnetic wave. Among the multifarious modulation methods, mechanical deformation is widely adopted to tune the electromagnetic response of the stereotype metamaterial owing to its straightforward and continuous controllability on the metamaterial structure. However, previous morphologic reconfigurations of metamaterials are typically confined in planar deformation that renders limited tunable functionalities. Here we have proposed a novel concept of out-of-plane deformation to broaden the functionalities of mechanically reconfigurable metamaterials via introducing a cross-shaped metamaterial. Our results show that the out-of-plane mechanical modulation dramatically enhances the magnetic response of the pristine metamaterial. Furthermore, by uncrossing the bars of cross-shaped meta-atoms, a L-shaped metamaterial is proposed to verify the effectiveness of such a mechanical method on the handedness switching via changing mechanical loading-paths. More importantly, the differential transmission for circularly polarized incidences can be continuously modulated from -0.45 to 0.45, and the polarization states of the transmission wave can be dynamically manipulated under the linearly polarized illumination. Our proposed mechanical modulation principle might open a novel avenue toward the three-dimensional reconfigurable metamaterials and shows their ample applications in the areas of chiroptical control, tunable polarization rotator and converter.