Laser-induced plasma micromachining on surfaces parallel to the incident laser in different solutions.

Laser-induced plasma micromachining (LIPMM) is an advanced technology that utilizes the plasma generated from laser breakdown to remove material, thereby facilitating the fabrication of microstructures. This paper explores the use of LIPMM on 304 stainless steel surfaces parallel to the laser beam in different solutions, focusing on the impact of the liquid environment on the machining process. It presents a theoretical analysis of the material removal mechanisms unique to this orientation and experimentally investigates how water, a salt solution, and ethanol affect plasma shockwave characteristics. Notably, the plasma shockwave in the salt solution demonstrates the most significant peak pressure and energy, enhancing the micromachining efficiency. These findings suggest that varying the liquid environment can significantly influence LIPMM's effectiveness, offering potential improvements in precision and control. This study broadens the understanding of LIPMM applications, especially in orientations not commonly explored, and opens new possibilities for advanced micromachining techniques in various industrial applications.

One-Pot Hydrothermal Method Preparation of Cerium-Nitrogen-Codoped Carbon Quantum Dots from Waste Longan Nucleus as a Fluorescent Sensor for Sensing Drug Rifampicin.

Currently, the large-scale application of carbon quantum dots (CQDs) is usually limited by their low quantum yield and detection limit. Herein, the abandoned longan nucleus was used as a carbon source to synthesize cerium-nitrogen-codoped carbon quantum dots (Ce/N-CQDs) with strong luminescence intensity. In this work, the fluorescent properties and fluorescent quantum yield of CQDs may be improved by the single cerium-doped carbon quantum dots (Ce-CQDs) and the single nitrogen-doped carbon quantum dots (N-CQDs). Nevertheless, the Ce/N-CQDs exhibited intense fluorescence with a high quantum yield. Compared with CQDs, the quantum yield of Ce/N-CQDs was significantly increased from 5 to 32% and showed high photostability and good water solubility. The Ce/N-CQDs can be used for the direct detection of rifampicin (RFP) in human serum. The concentration demonstrated a good linear relationship in the range of 1.0 × 10-7-9.0 × 10-6 mol/L, with a detection limit of 9.6 × 10-8 mol/L.

Five Mesoporous Lanthanide Metal-Organic Frameworks: Syntheses, Structures, and Fluorescence Sensing of Fe3+, Cr2O72-, and H2O2 and Electrochemical Sensing of Trinitrophenol.

When a multicarboxylate aromatic ligand, 3,5-di(2',4'-dicarboxylphenyl)benzoic acid (H5L), was employed, five structurally similar lanthanide metal-organic frameworks (Ln-MOFs), {[Pr10L6(OH)3Cl(H2O)6]·4C2H8N}n (1), {[Nd10L6(OH)4 (H2O)9]·4C2H8N}n (2), {[Gd10L6(OH)4(H2O)3]·4C2H8N}n (3), {[Ho10L6(OH)4 (H2O)3]·4C2H8N}n (4) and {[Er10L6(OH)4(H2O)6]·4C2H8N}n (5), were synthesized and characterized. Single-crystal X-ray structural analyses disclosed that all five Ln-MOFs crystallize in the trigonal R3 space group. They have three-dimensional mesoporous structure featuring the coexistence of binuclear and tetranuclear species as inorganic building units. The mesoporous structure of 3 was verified by the gas adsorption experiment of N2. Fluorescence analysis showed that 3 can selectively detect Fe3+, Cr2O72-, and H2O2; furthermore, it can be used for the electrochemical detection of trinitrophenol. With the merit of an excellent highly sensitive detection performance, 3 has unpredictable application prospects in future research fields.

One-pot two-step process directly converting biomass-derived carbohydrate to lactide.

This study proposed a strategy for the production of lactide from biomass-derived carbohydrate with excellent yield, involving sugar to racemic lactic acid conversion over Sn-containing Beta zeolite and racemic lactic acid to lactide conversion over H-Beta zeolite. Structural characteristics of the resulting lactide and extensive applicability for various substrates are also presented.

Product Control and Insight into Conversion of C6 Aldose Toward C2, C4 and C6 Alditols in One-Pot Retro-Aldol Condensation and Hydrogenation Processes.

Alcohols have a wide range of applicability, and their functions vary with the carbon numbers. C6 and C4 alditols are alternative of sweetener, as well as significant pharmaceutical and chemical intermediates, which are mainly obtained through the fermentation of microorganism currently. Similarly, as a bulk chemical, C2 alditol plays a decisive role in chemical synthesis. However, among them, few works have been focused on the chemical production of C4 alditol yet due to its difficult accumulation. In this paper, under a static and semi-flowing procedure, we have achieved the product control during the conversion of C6 aldose toward C6 alditol, C4 alditol and C2 alditol, respectively. About C4 alditol yield of 20 % and C4 plus C6 alditols yield of 60 % are acquired in the one-pot conversion via a cascade retro-aldol condensation and hydrogenation process. Furthermore, in the semi-flowing condition, the yield of ethylene glycol is up to 73 % thanks to its low instantaneous concentration.

Observing a Zeolite Nucleus (Subcrystal) with a Uniform Framework Structure and Its Oriented Attachment without Single-Molecule Addition.

Multiple and complex crystallization process of zeolite including complementary single-molecule condensation and particle assembly, and alternately dominant nucleation and growth behavior, plays the critical role in zeolite crystallization but meanwhile makes us hard to study the respective effects. Herein, we strip nuclei from the synthetic solution and find that high-ordered nucleus (subcrystal) is the premise to ignite high-speed growth of zeolite crystal. The high-ordered subcrystals with the size of only 6-10 nm possess regular aperture structure and microporous area similar to zeolite nanocrystal. Interestingly, a unitary oriented aggregation process of the subcrystals towards nanosheets is well observed and characterized where single-molecule addition process is greatly repressed. If a wider range of zeotype nuclei can be expanded, a new synthetic strategy of zeotype materials with heterogeneous framework and active sites may be expected, which may novelize zeolite catalytic properties.

Novel Multifunctional Samarium-Organic Framework for Fluorescence Sensing of Ag+, MnO4 -, and Cimetidine and Electrochemical Sensing of o-Nitrophenol in Aqueous Solutions.

A novel Sm-metal-organic framework (MOF) sensor with the molecular formula Sm8(HDBA)6·H2O has been prepared based on a penta-carboxyl organic ligand (H5DBA = 3,5-di(2',4'-dicarboxylphenyl)benzoic acid) and samarium nitrate under solvothermal conditions. Sm-MOF is characterized by single-crystal X-ray diffraction analysis, elemental analysis, thermogravimetric analysis, and powder X-ray diffraction analysis. Structural analysis shows that the dimer metal units are alternately connected to form a one-dimensional chain, and this chain is connected by the bridging carboxyl oxygen of the ligand H5DBA to form a two-dimensional double-layer plane, which then expands into a three-dimensional microporous framework. Fluorescence detection studies show that Sm-MOF can detect Ag+ ions, MnO4 - anions, and cimetidine tablets with high sensitivity and selectivity and can also be used to electrochemically detect o-nitrophenol in water. High-sensitivity detection capability of the Sm-MOF can enrich the application of samarium complexes in multifunctional sensors.

Experimental investigations of three laser-induced synchronized bubbles.

Herein, we investigated experimentally the dynamics of three laser-induced, same-sized, symmetrically aligned, and synchronized bubbles. Three synchronized laser beams split from the same beam using a Diffractive Optical Element splitter were focused on water, and then we obtained three bubbles. Another nanosecond laser pulse was used to probe the bubbles to obtain shadowgraphs. The exact delay of the excited and detected light was controlled using a delay generator. The results revealed that the maximum volumes of bubbles in arrays decrease as the normalized distance falls, while the lifetimes and translation increase. It was explained by the interaction between the acoustic radiation of bubbles and the surrounding bubbles. The shrinkage of linear bubble arrays exists an anomaly. The center bubbles were stretched, to ellipsoid, stick, even fractured, by the peripheral bubbles. The closer they are, the more distinct is the above phenomenon. However, when the normalized distance was sufficiently small, instead of being stretched, the center bubbles were compressed to disk shape and thus shrank with the whole array. Finally, the dependence of the distance on the energy transfer of the bubble system is also discussed.

A Multifunctional Tb-MOF Detector for H2O2, Fe3+, Cr2O7 2-, and TPA Explosive Featuring Coexistence of Binuclear and Tetranuclear Clusters.

A novel three-dimensional microporous terbium(III) metal-organic framework (Tb-MOF) named as [Tb10 (DBA)6(OH)4(H2O)5]·(H3O)4 (1), was successfully obtained by a solvothermal method based on terbium nitrate and 5-di(2',4'-dicarboxylphenyl) benzoic acid (H5DBA). The Tb-MOF has been characterized by single crystal X-ray diffraction, elemental analysis, thermogravimetry, and fluorescence properties, and the purity was further confirmed by powder X-ray diffraction (PXRD) analysis. Structural analysis shows that there are two kinds of metal cluster species: binuclear and tetranuclear, which are linked by H5DBA ligands in two µ7 high coordination fashions into a three-dimensional microporous framework. Fluorescence studies show that the Tb-MOF can detect H2O2, Fe3+, and Cr2O7 2- with high sensitivity and selectivity and can also be used for electrochemical detection of exposed 2,4,6-trinitrophenylamine (TPA) in water. The highly selective and sensitive detection ability of the Tb-MOF might make it a potential multifunctional sensor in the future.

Water-assisted isomerization of the [H, C, N, O] system.

Ten minima of [H, C, N, O] isomers were investigated in gas phase and water solution using the polarizable continuum model at the CCSD(T)//M06-2X/6-311 + G(3df,2p) level of theory. The results show that the stability order of all isomers in water solution is HNCO > HOCN > HCNO > HONC > Y-OC(H)N > cycl-OCN(H)-a ≈ cycl-OCN(H)-b > cycl-NCO(H) > HNOC > HCON, i.e., the same as that in the gas phase. Potential energy surfaces of [H, C, N, O] system isomerization were constructed in gas phase and in water solution, showing that the isomerization of [H, C, N, O] isomers in gas phase is unfavorable because of the high barrier height. Interestingly, although the water solvent has a little impact on the isomeric mechanism, water molecules (H2O)n(n = 1-3) acting as catalyst dramatically lower the barrier height in the hydrogen transfer processes (HCNO → HONC, HNCO → HOCN, and HCON → HNOC). Water is the most abundant compound in the interstellar area. These results give new insight into the mechanism of [H, C, N, O] system isomerization in interstellar gas. Enthalpies of formation of the isomers were predicted at the CBS-QB3, G4MP2 and W1U levels.

µ-4,4'-Bipyridine-bis-[aqua-(4-hy-droxy-pyridine-2,6-dicarboxyl-ato)copper(II)].

The title compound, [Cu(2)(C(7)H(3)NO(5))(2)(C(10)H(8)N(2))(H(2)O)(2)], exhibits a centrosymmetric binuclear molecule. Each completely deprotonated 4-hy-droxy-pyridine-2,6-dicarb-oxy-lic acid mol-ecule assumes a tridentate chelating coordination mode. The square-pyramidal coordination geometry around the Cu(II) ion is completed by the bridging bipyridine ligand and an apical water molecule. Adjacent complexes are connected via O-H⋯O and C-H⋯O hydrogen bonds to generate a three-dimensional supra-molecular structure.