Two-step demodulation based on the Gram-Schmidt orthonormalization method

This Letter presents an efficient, fast, and straightforward two-step demodulating method based on a Gram-Schmidt (GS) orthonormalization approach. The phase-shift value has not to be known and can take any value inside the range (0,2π), excluding the singular case, where it corresponds to π. The proposed method is based on determining an orthonormalized interferogram basis from the two supplied interferograms using the GS method. We have applied the proposed method to simulated and experimental interferograms, obtaining satisfactory results. A complete MATLAB software package is provided at http://goo.gl/IZKF3.     

The Kohn-Sham kinetic energy density as indicator of the electron localization: atomic shell structure

In this report, it is shown that the Kohn-Sham (KS) kinetic energy density (KED) contains the average local electrostatic potential (ALEP) and the average local ionization energy (ALIE); the shell structure in atomic systems is presented as one application of the KS-KED. By writing the KS-KED from the KS equations, this quantity was divided in three contributions: orbital, Coulomb, and exchange correlation. By studying several closed and open shell atoms, the shell structure was established by the maxima presented by the Coulomb contribution and the minima in the orbital contribution of the KS-KED. The exchange-correlation contribution to the KS-KED does not show maxima or minima, but this quantity shows bumps where the division between shells is expected. The results obtained in this work were compared with other shell structure indicators such as the electron localization function, the ALEP, the ALIE, and the radial distribution function. The most important result in this work is related to the fact that even when the ALEP and the ALIE functions were built with different arguments to each other, they are contained in the KS-KED. In this way, the KS-KED shows its importance to reveal the electron localization in atomic systems.     

Diboryldiborenes: π‐Conjugated B4 Chains Isoelectronic to the Butadiene Dication

B(sp²)–B(sp³) diborane species based on bis(catecholato)diboron and N‐heterocyclic carbenes (NHCs) underwent catechol/bromide exchange selectively at the sp³‐hybridized boron atom. The reduction of the resulting 1,1‐dibromodiborane adducts led to reductive coupling and isolation of doubly NHC‐stabilized 1,2‐diboryldiborenes. These compounds are the first examples of molecules exhibiting π‐electron delocalization over an all‐boron chain.     

Unsymmetrical,Cyclic Diborenes and Thermal Rearrangement to a Borylborylene

Cyclic diboranes(4) based on a chelating monoanionic benzylphosphine linker were prepared through boron–silicon exchange between arylsilanes and B₂Br₄. Coordination of Lewis bases to the remaining sp² boron atom yielded unsymmetrical sp³‐sp³ diboranes, which were reduced with KC₈ to their corresponding trans‐diborenes. These compounds were studied with a combination of spectroscopic methods, X‐ray diffraction, and DFT calculations. PMe₃‐stabilized diborene 6 was found to undergo thermal rearrangement to gem‐diborene 8 . DFT calculations on 8 reveal a polar boron–boron bond, and indicate that the compound is best described as a borylborylene.     

Chemical modification of activated carbon monoliths for CO2 adsorption

The development of materials with potential application for CO₂ capture is a topic of great scientific interest. Activated carbons (AC) can be conveniently used as CO₂ adsorbents thanks to their microporous structure and tunable chemical properties. In this work, two AC honeycomb monoliths were synthesized starting from African palm stones through activation either with H₃PO₄ or with ZnCl₂ solution. Surface functionalization was performed in order to add nitrogen groups, aiming at an enhancement of CO₂ adsorption capacity. This chemical modification was performed either with ammonia in gas phase or a with 30 % ammonium hydroxide aqueous solution on both AC monolith samples. The original and modified monoliths were characterized by N₂ adsorption at 77 K, infrared spectroscopy, Boehm titration, and immersion calorimetry in benzene and water. CO₂ adsorption on both raw and functionalized AC monoliths was evaluated in volumetric equipment at a temperature of 273 K and until 1 bar, and adsorption capacity ranging between 120 and 220 mg_CO2 g _AC ^?1 was obtained. The experimental results indicated that both methods of chemical modification determined an increase in the content of superficial nitrogen groups and thus an increase in CO₂ adsorption capacity, the treatment with ammonium hydroxide being slightly preferable.     

A Study of Synthesis, Immobilization and Catalytic Capability of Metalloporphyrin

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Open tubular liquid chromatography: Recent advances and future trends

Nano-liquid chromatography (nanoLC) is gaining significant attention as a primary analytical technique across various scientific domains. Unlike conventional high-performance LC, nanoLC utilizes columns with inner diameters (i.ds.) usually ranging from 10 to 150 μm and operates at mobile phase flow rates between 10 and 1000 nl/min, offering improved chromatographic performance and detectability. Currently, most exploration of nanoLC has focused on particle-packed columns. Although open tubular LC (OTLC) can provide superior performance, optimized OTLC columns require very narrow i.ds. (< 10 μm) and demand challenging instrumentation. At the moment, these challenges have limited the success of OTLC. Nevertheless, remarkable progress has been made in developing and utilizing OTLC systems featuring narrow columns (< 2 μm). Additionally, significant efforts have been made to explore larger columns (10–75 μm i.d), demonstrating practical applicability in many situations. Due to their perceived advantages, interest in OTLC has resurged in the last two decades. This review provides an updated outlook on the latest developments in OTLC, focusing on instrumental challenges, achievements, and advancements in column technology. Moreover, it outlines selected applications that illustrate the potential of OTLC for performing targeted and untargeted studies.