High-Performance Trimethylamine Sensor Based on an Imine Covalent Organic Framework.

As trimethylamine (TMA) is widely used in agriculture and industry, inhalation of TMA can cause very serious negative effects on human health. However, most of the current gas sensors for detecting TMA are commonly performed at high temperatures and cannot meet market needs. Inspired by this, we prepared imine covalent organic frameworks (TB-COF) synthesized from two monomers, 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 1,3,5-benzotricarboxaldehyde (BTCA), using acetic acid as a catalyst at room temperature. Based on this, three sensors were prepared for gas sensitivity testing, namely, TA, BT, and TB-COF sensors. The three sensors were tested for 15 different gases at room temperature. From the whole gas sensitivity data, the TB-COF sensor made by compositing TA and BT has a higher sensitivity (6845.9%) to TMA at 500 ppm, which is 6.1 and 5.4 times higher than the response of TA and BT sensors, respectively. The TB-COF sensor adsorbs and desorbs TMA in a controlled 23 s cycle with a low detection limit of 28.6 ppb. This result indicates that TB-COF prepared at room temperature can be used as a gas-sensitive sensing material for real-time monitoring of TMA. The gas sensing results demonstrate the great potential of COFs for sensor development and application and provide ideas for further development of COFs-based gas sensors.

Universal Deoxidation of Semiconductor Substrates Assisted by Machine Learning and Real-Time Feedback Control.

Substrate oxidation is inevitable when exposed to ambient atmosphere during semiconductor manufacturing, which is detrimental to the fabrication of state-of-the-art devices. Optimizing the deoxidation process in molecular beam epitaxy (MBE) for random substrates poses a multidimensional challenge and is sometimes controversial. Due to variations in substrates and growth processes, the determination of the deoxidation condition heavily relies on the individual's expertise, yielding inconsistent results. This study employs a machine learning model that integrates interpolation and vision transformer (Interpolation-ViT) techniques. The model utilizes reflection high-energy electron diffraction videos as input to predict the status of the substrate, enabling automated deoxidation within a controlled architecture for various substrates. Furthermore, we highlight the potential of models trained on data from specific MBE equipment to achieve high-accuracy deployment on different pieces of equipment. In contrast to traditional methods, our approach holds exceptional value, as it standardizes deoxidation temperatures across diverse equipment and substrates. This significantly advances the standardization of the semiconductor process. The concepts and methods presented are expected to revolutionize semiconductor manufacturing processes in the optoelectronic and microelectronic industries.

Machine-learning-assisted and real-time-feedback-controlled growth of InAs/GaAs quantum dots.

The applications of self-assembled InAs/GaAs quantum dots (QDs) for lasers and single photon sources strongly rely on their density and quality. Establishing the process parameters in molecular beam epitaxy (MBE) for a specific density of QDs is a multidimensional optimization challenge, usually addressed through time-consuming and iterative trial-and-error. Here, we report a real-time feedback control method to realize the growth of QDs with arbitrary density, which is fully automated and intelligent. We develop a machine learning (ML) model named 3D ResNet 50 trained using reflection high-energy electron diffraction (RHEED) videos as input instead of static images and providing real-time feedback on surface morphologies for process control. As a result, we demonstrate that ML from previous growth could predict the post-growth density of QDs, by successfully tuning the QD densities in near-real time from 1.5 × 1010 cm-2 down to 3.8 × 108 cm-2 or up to 1.4 × 1011 cm-2. Compared to traditional methods, our approach can dramatically expedite the optimization process and improve the reproducibility of MBE. The concepts and methodologies proved feasible in this work are promising to be applied to a variety of material growth processes, which will revolutionize semiconductor manufacturing for optoelectronic and microelectronic industries.

Correction: The {Cu2I2} cluster bearing metal organic frameworks: crystal structures and fluorescence detecting performances towards cysteine and explosive molecules.

Correction for 'The {Cu2I2} cluster bearing metal organic frameworks: crystal structures and fluorescence detecting performances towards cysteine and explosive molecules' by Jiang Jiang et al., Dalton Trans., 2024, 53, 706-714, https://doi.org/10.1039/d3dt03363e.

Green Synthesis of Carbon Quantum dots Derived from Lycium barbarum for Effective Fluorescence Detection of Cr (VI) Sensing.

Green and economical self-doped nitrogen-containing fluorescent carbon quantum dots (N-CQDs) were synthesized using a one-pot hydrothermal treatment method. The optical and structural properties of the N-CQDs were investigated in detail by UV-vis and fluorescence spectroscopy, X-ray diffraction (XRD) techniques, transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HRTEM). Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) spectroscopy, and elemental analysis illustrate the surface function and composition of N-CQDs. N-CQDs emit a broad fluorescence between365 Ì´ 465 nm and fluoresce most strongly at the excitation wavelength of 415 nm. Meanwhile, Cr (VI) could significantly burst the fluorescence intensity of N-CQDs. N-CQDs showed an excellent sensitivity and selectivity to Cr (VI), which exhibited good linearity in the range of 0 Ì´ 40 µmol/L with a detection limit of 0.16 µmol/L. In addition, the mechanism of Fluorescence quenching of N-CQDs by Cr (VI) was investigated. This work well provides a research idea for the preparation of green carbon quantum dots from biomass and their use for the detection of metal ions.

The {Cu2I2} cluster bearing metal organic frameworks: crystal structures and fluorescence detecting performances towards cysteine and explosive molecules.

Two {Cu2I2} cluster-bearing metal organic frameworks (MOFs) of {[Eu(CuI)2(INA)3DMF]·0.95DMF}n (Eu-CuI-INA) and {K[(CH3)2NH2]Sr4(INA)2(DMF)2{(Cu2I2)2(INA)8}·2H2O}n (Sr-K-CuI-INA, HINA = isonicotinic acid, DMF = N,N-dimethyl formamide) were prepared and characterized in this work. Both materials feature a three-dimensional (3-D) structure, in which the {Cu2I2} clusters and Eu3+ (or Sr2+) metal ions are coordinated by INA- ligands with pyridine and carboxylic groups, respectively. Impressively, Sr-K-CuI-INA exhibits sensitive fluorescence sensing behaviors towards cysteine and nitro-bearing molecules, demonstrating potential FL sensing applications for bio and explosive molecules. This work would provide a good reference for designing fluorescent MOF probes containing CuI molecules.

High-Performance Ethylene Glycol Sensor Based on Imine Covalent Organic Frameworks.

The colorless and odorless ethylene glycol is prone to unknowingly causing poisoning, making preventive monitoring of ethylene glycol necessary. In this paper, scandium (III) trifluoromethanesulfonate was used as a catalyst to successfully prepare covalent organic framework (COF) nanospheres linked by imines at room temperature. The COF nanospheres were characterized by XRD, SEM, TEM, FT-IR, UV-Vis and BET. The results show that COF nanospheres have rough surfaces and a large number of mesoporous structures, which greatly increase the active sites on the surface of the sensing material and enhance the gas sensing performance. The sensing results showed that the prepared imine-conjugated COF nanospheres exhibited a good response-recovery ability for 10 consecutive response-recovery cycles for ethylene glycol at room temperature and had a theoretical detection limit of 40 ppb. In addition, the responses of COF nanospheres to nearly 20 interfering gases, including HCl, HNO3, phenol, formaldehyde and aniline, are relatively low compared to the response to ethylene glycol, indicating that the COF nanospheres have high selectivity towards ethylene glycol. The COF nanospheres show good sensitivity and selectivity for the detection of ethylene glycol, which should be attributed to the large specific surface area, hydrogen bonding interactions, and high defects. This work provides an effective method for the detection of ethylene glycol and expands the application field of COF materials.

A Soluble Porous Coordination Polymer for Fluorescence Sensing of Explosives and Toxic Anions under Homogeneous Environment.

In the past decades, porous coordination polymers (PCPs) based fluorescent (FL) sensors have received intense attention due to their promising applications. In this work, a soluble Zn-PCP is presented as a sensitive probe towards explosive molecules, chromate, and dichromate ions. In former reports, PCP sensors were usually ground into fine powders and then dispersed in solvents to form FL emulsion for sensing applications. However, their insoluble characters would cause the sensing accuracy which is prone to interference from environmental effects. While in this work, the as-made PCP could be directly soluble in organic solvents to form a clear solution with bright blue emission, representing the first soluble PCP based fluorescence sensor to probe explosive molecules under a homogeneous environment. Moreover, the FL PCP solution also shows sensitive detection behaviors towards the toxic anions of CrO42- and Cr2O72-, which exhibit a good linear relationship between the fluorescence intensity of Zn-PCP and the concentrations of both analytes. This work provides a reference for designing task-specific PCP sensors utilized under a homogeneous environment.

Confinement of 1D Chain and 2D Layered CuI Modules in K-INA-R Frameworks via Coordination Assembly: Structure Regulation and Semiconductivity Tuning.

Herein, we present a new series of CuI-based hybrid materials with tunable structures and semiconducting properties. The CuI inorganic modules can be tailored into a one-dimensional (1D) chain and two-dimensional (2D) layer and confined/stabilized in coordination frameworks of potassium isonicotinic acid (HINA) and its derivatives (HINA-R, R = OH, NO2, and COOH). The resulting CuI-based hybrid materials exhibit interesting semiconducting behaviors associated with the dimensionality of the inorganic module; for instance, the structures containing the 2D-CuI module demonstrate significantly enhanced photoconductivity with a maximum increase of five orders of magnitude compared to that of the structures containing the 1D-CuI module. They also represent the first CuI-bearing hybrid chemiresistive gas sensors for NO2 with boosted sensing performance and sensitivity at multiple orders of magnitude over that of the pristine CuI. Particularly, the sensing ability of CuI-K-INA containing both 1D- and 2D-CuI modules is comparable to those of the best NO2 chemiresistors reported thus far.

Moisture-Resistant and Highly Selective NH3 Sensor Based on CdS/WS2 Composite Heterojunction.

This study reports the synthesis of CdS/WS2 composites via a green and ultra-low-cost hydrothermal method. By controlling the relative mass ratio between WS2 and CdS, an n-n type CdS/WS2 heterostructure, with excellent NH3 gas-sensitive properties, was developed and investigated at room temperature. Compared with pristine WS2 and CdS, the CdS/WS2-40%wt composite exhibited excellent selectivity of more than 4 orders of magnitude for sensing NH3, a very short recovery time of 3 s, and ultrahigh selectivity at room temperature. The large specific surface area of the CdS/WS2 composite increased the active sites for the gas-sensitive reaction. Additionally, the 2D morphology of CdS/WS2 and the heterojunction formed between WS2 and CdS contributed to the improved performance. Anti-humidity interference tests showed that the CdS/WS2 sample remained stable under real-time monitoring of NH3 at different ambient humidity values. This study paves the way for designing high-performance gas sensors operating at room temperature.

Investigation of the optimal indocyanine green dose in real-time fluorescent cholangiography during laparoscopic cholecystectomy with an ultra-high-definition 4K fluorescent system: a randomized controlled trial.

This study aimed to investigate the indocyanine green (ICG) dose in real-time fluorescent cholangiography during laparoscopic cholecystectomy (LC) with a 4K fluorescent system. A randomized controlled clinical trial was conducted in patients who underwent LC for treatment of cholelithiasis. Using the OptoMedic 4K fluorescent endoscopic system, we compared four different doses of ICG (1, 10, 25, and 100 µg) administered intravenously within 30 min preoperatively and evaluated the fluorescence intensity (FI) of the common bile duct and liver background and the bile-to-liver ratio (BLR) of the FI at three timepoints: before surgical dissection of the cystohepatic triangle, before clipping the cystic duct, and before closure. Forty patients were randomized into four groups, and 33 patients were fully analyzed, with 10 patients in Group A (1 µg), 7 patients in Group B (10 µg), 9 patients in Group C (25 µg), and 7 patients in Group D (100 µg). The preoperative baseline characteristics were compared among groups (p > 0.05). Group A showed no or minimal FI in the bile duct and liver background, while Group D showed extremely high FIs in the bile duct and in the liver background at the three timepoints. Groups B and C presented with visible FI in the bile duct and low FI in the liver background. With increasing ICG doses, the FIs in the liver background and bile duct gradually increased at the three timepoints. The BLR, however, showed no increasing trend with an increasing ICG dose. A relatively high BLR on average was found in Group B, without a significant difference compared to the other groups (p > 0.05). An ICG dose ranging from 10 to 25 µg by intravenous administration within 30 min preoperatively was appropriate for real-time fluorescent cholangiography in LC with a 4K fluorescent system. Registration: This study was registered in the Chinese Clinical Trial Registry (ChiCTR No: ChiCTR2200064726).

Synthesis and Sensing Performance of Chitin Fiber/MoS2 Composites.

In this study, chitin fibers (CFs) were combined with molybdenum sulfide (MoS2) to develop high-performance sensors, and chitin carbon materials were innovatively introduced into the application of gas sensing. MoS2/CFs composites were synthesized via a one-step hydrothermal method. The surface properties of the composites were greatly improved, and the fire resistance effect was remarkable compared with that of the chitin monomer. In the gas-sensitive performance test, the overall performance of the MoS2/CFs composite was more than three times better than that of the MoS2 monomer and showed excellent long-term stability, with less than 10% performance degradation in three months. Extending to the field of strain sensing, MoS2/CFs composites can realize real-time signal conversion in tensile and motion performance tests, which can help inspectors make analytical judgments in response to the analysis results. The extensive application of sensing materials in more fields is expected to be further developed. Based on the recycling of waste chitin textile materials, this paper expands the potential applications of chitin materials in the fields of gas monitoring, biomedicine, behavioral discrimination and intelligent monitoring.

Confinement of Pyridine Derivatives into a Metal-Organic Framework Host as Electron Acceptors to Achieve Photoinduced Electron-Transfer.

The photoinduced electron-transfer (ET) process plays an irreplaceable role in chemical and biological fields exemplified by enzymatic catalysis, artificial photosystems, solar energy conversion, and so forth. Searching for a new photoinduced ET system is of great importance for the development of functional materials. Herein, a series of host-guest compounds based on a magnesium metal-organic framework (Mg-MOF) as a host and pyridine derivatives as guests have been presented. Notably, strong O-H···N hydrogen bond between the oxygen atom of µ2-H2O and the nitrogen atom of pyridine enables proton delocalization between water molecule and pyridine guest. Despite the absence of photochromic modules in these host-guest compounds, long-lived charge-separated states with distinct color changes can be formed after UV-light irradiation. The substituents in pyridines and the proton delocalization ability between the host and guests have a great influence on their photoinduced ET process to endow the MOF materials with tunable photoinduced charge-separated states.

Oxygen Vacancies-Rich S-Cheme BiOBr/CdS Heterojunction with Synergetic Effect for Highly Efficient Light Emitting Diode-Driven Pollutants Degradation.

Recently, the use of semiconductor-based photocatalytic technology as an effective way to mitigate the environmental crisis attracted considerable interest. Here, the S-scheme BiOBr/CdS heterojunction with abundant oxygen vacancies (Vo-BiOBr/CdS) was prepared by the solvothermal method using ethylene glycol as a solvent. The photocatalytic activity of the heterojunction was investigated by degrading rhodamine B (RhB) and methylene blue (MB) under 5 W light-emitting diode (LED) light. Notably, the degradation rate of RhB and MB reached 97% and 93% in 60 min, respectively, which were better than that of BiOBr, CdS, and BiOBr/CdS. It was due to the construction of the heterojunction and the introduction of Vo, which facilitated the spatial separation of carriers and enhanced the visible-light harvest. The radical trapping experiment suggested that superoxide radicals (·O2-) acted as the main active species. Based on valence balance spectra, Mott-Schottky(M-S) spectra, and DFT theoretical calculations, the photocatalytic mechanism of the S-scheme heterojunction was proposed. This research provides a novel strategy for designing efficient photocatalysts by constructing S-scheme heterojunctions and introducing oxygen vacancies for solving environmental pollution.

A Cerium Organic Framework with {Cu2I2} Cluster and {Cu2I2}n Chain Modules: Structure and Fluorescence Sensing Properties.

In this work, a copper iodine module bearing a coordination polymer (CP) with a formula of [(Cu2I2)2Ce2(INA)6(DMF)3]·DMF (1, HINA = isonicotinic acid, DMF = N,N'-dimethyl formamide) is presented. The title compound features a three dimensional (3D) structure, in which the {Cu2I2} cluster and {Cu2I2}n chain modules are coordinated by N atoms from a pyridine ring in INA- ligands, while the Ce3+ ions are bridged by the carboxylic groups of INA- ligands. More importantly, compound 1 exhibits an uncommon red fluorescence (FL) with a single emission band maximized at 650 nm belonging to near infrared (NIR) luminescence. The temperature dependent FL measurement was applied to investigate the FL mechanism. Remarkably, 1 could be used as a FL sensor to cysteine and the nitro-bearing explosive molecule of trinitropheno (TNP) with high sensitivity, demonstrating its potential FL sensing applications for biothiol and explosive molecules.

A Microwave Field-Induced Nonlinear Metamaterial with Wafer Integration Level.

Field-induced nonlinear materials, with extended abilities of manipulating electromagnetic waves, have been widely employed in electromagnetic protection, absorption, and detection. Until now, it was found that the field-induced nonlinearity mainly shows in the optical and terahertz frequency bands. Applying the microwave band into such technical activities is hampered due to a lack of investigations on the nonlinearity caused by microwave electric fields, especially in the ultrawideband and microwave high-frequency bands. In this paper, a nonlinear metamaterial (NLMM) concept based on the integration of metamaterial structures and a semiconductor on the same wafer is proposed, which shows nonlinear behavior to the electromagnetics' field energy in the microwave band. The designed NLMM is transparent to low-density electromagnetic radiation fields, while it adaptively becomes opaque to high-density electromagnetic radiation fields. Two types of NLMM are designed to verify the nonlinear characteristics of ultrawide and narrow bands in the microwave band, respectively. The concept of NLMM can be used for the application of the microwave frequency band in electromagnetic protection and detection.

A Robust Strontium Coordination Polymer with Selective and Sensitive Fluorescence Sensing Ability for Fe3+ Ions.

Exploration of sensitive and selective fluorescence sensors towards toxic metal species is of great importance to solve metal pollution issues. In this work, a three-dimensional (3D) strontium coordination polymer of Sr2(tcbpe) (H4tcbpe = 1,1,2,2-tetrakis(4-(4-carboxy-phenyl)phenyl)ethene) has been synthesized and developed as a fluorescent sensor to Fe3+ ions. Sr2(tcbpe) shows a mechanochromic fluorescence with emission shifting from blue of the pristine to green after being ground. Notably, based on a fluorescence quenching mechanism, Sr2(tcbpe) displays a sensitive and selective fluorescent sensing behavior to Fe3+ ions with a detection limit of 0.14 mM. Moreover, Sr2(tcbpe) exhibits high tolerance to water in a wide pH range (pH = 3-13), demonstrating that Sr2(tcbpe) is a potential fluorescent sensor of Fe3+ in water.

Single-Crystal Superstructures via Hierarchical Assemblies of Giant Rubik's Cubes as Tertiary Building Units.

Intricate superstructures possess unusual structural features and promising applications. The preparation of superstructures with single-crystalline nature are conducive to understanding the structure-property relationship, however, remains an intriguing challenge. Herein we put forward a new hierarchical assembly strategy towards rational and precise construction of intricate single-crystal superstructures. Firstly, two unprecedented superclusters in Rubik's cube's form with a size of ≈2×2×2 nm3 are constructed by aggregation of eight {Pr4 Sb12 } oxohalide clusters as secondary building units (SBUs). Then, the Rubik's cubes further act as isolable tertiary building units (TBUs) to assemble diversified single-crystal superstructures. Importantly, intermediate assembly states are captured, which helps illustrate the evolution of TBU-based superstructures and thus provides a profound understanding of the assembly process of superstructures at the atomic level.

Real-time fluorescent cholangiography with indocyanine green in laparoscopic cholecystectomy: a randomized controlled trial to establish the optimal indocyanine green dose within 30 min preoperatively.

PURPOSE: To establish the optimal dose of indocyanine green (ICG) to administer intravenously 30 min before laparoscopic cholecystectomy (LC). METHODS: In this randomized controlled trial (RCT), patients undergoing LC for cholecystitis, cholelithiasis, and/or cholecystic polyps were randomized into four groups given four different ICG doses (0.025, 0.1, 0.25, 2.5 mg). Using OptoMedic endoscopy combined with a near-infrared fluorescent imaging system, we evaluated the fluorescence intensity (FI) of the common bile duct and liver at three timepoints: before surgical dissection of the cystohepatic triangle, before clipping of the cystic duct, and before closure. The bile duct-to-liver ratio (BLR) of the FI was analyzed to assess the cholangiography effect. RESULTS: Sixty-four patients were allocated to one of four groups, with 40 patients included in the final analysis. Generally, with increasing ICG doses, the levels of FI in the bile duct and liver increased gradually at each of the three timepoints. Before surgical dissection of the cystohepatic triangle, 0.1-mg ICG showed the highest BLR (F = 3.47, p = 0.0259). Before clipping the cystic duct and before closure, the 0.025- and 0.1-mg groups showed a higher BLR than the 0.25- and 2.5-mg groups (p < 0.05). When setting the ideal cholangiography at a BLR ≥ 1, ≥ 3, or ≥ 5, the 0.1-mg group showed the highest qualified case number at the three timepoints. CONCLUSIONS: The intravenous administration of 0.1-mg ICG, 30 min before LC, is significantly better for fluorescent cholangiography of the extrahepatic biliary structures before dissection and clipping of the cystohepatic triangle. TRIAL REGISTRATION: This study was registered in the Chinese Clinical Trial Registry (ChiCTR) (ChiCTR2200057933).

An Iron-NDC Framework with a Cage Structure and an Optothermal Conversion in NIR Window.

Pursuing novel materials with efficient photothermal conversion under irradiation at the near-infrared region windows (NIR, 750-850 nm; NIR-I and NIR-II, 1000-1320 nm)) is of great importance due to their irreplaceable applications, especially in the biomedical field. Herein, on the basis of a coordination chemistry strategy, an iron-based metal-organic framework (MOF) of [N(CH3)4]2[Fe3(NDC)4]·DMF·3H2O (Fe-NDC, 1,4-H2NDC = 1,4-naphthalenedicarboxylic acid, N(CH3)4+ = tetramethyl-ammonium, and DMF = N,N-dimethylformamide) was prepared and characterized. Due to the d-d transition effect introduced by coordination with the transition-metal ion of iron and the highly conjugated naphthalenic moiety in 1,4-H2NDC, guaranteeing an energy transfer between iron and the organic module, Fe-NDC shows a remarkable broad absorption, which could be extended into the NIR-II section. As a result, Fe-NDC could be irradiated by NIR laser (both 808 and 1064 nm) to achieve photothermal conversion. This work sets a good example to inspire the future designation of NIR light-irradiated photothermal materials based on the first-row transition metals.