Bulk Depolymerization of Methacrylate Polymers via Pendent Group Activation.

In this study, we present an efficient approach for the depolymerization of poly(methyl methacrylate) (PMMA) copolymers synthesized via conventional radical polymerization. By incorporating low mol % phthalimide ester-containing monomers during the polymerization process, colorless and transparent polymers closely resembling unfunctionalized PMMA are obtained, which can achieve >95% reversion to methyl methacrylate (MMA). Notably, our catalyst-free bulk depolymerization method exhibits exceptional efficiency, even for high-molecular-weight polymers, including ultrahigh-molecular-weight (106-107 g/mol) PMMA, where near-quantitative depolymerization is achieved. Moreover, this approach yields polymer byproducts of significantly lower molecular weight, distinguishing it from bulk depolymerization methods initiated from chain ends. Furthermore, we extend our investigation to polymethacrylate networks, demonstrating high extents of depolymerization. This innovative depolymerization strategy offers promising opportunities for the development of sustainable polymethacrylate materials, holding great potential for various applications in polymer science.

Photocleavable Visible Light-Triggered Anthraquinone-Derived Water-Soluble Block Copolymer for Peroxynitrite Generation in Cancer Therapy.

We report a facile stimuli-responsive strategy to generate reactive oxygen and nitrogen species (ROS and RNS) in the biological milieu from a photocleavable water-soluble block copolymer under visible light irradiation (427 nm, 2.25 mW/cm2). An anthraquinone-based water-soluble polymeric nitric oxide (NO) donor (BCPx-NO) is synthesized, which exhibits NO release in the range of 40-65 µM within 10 h of photoirradiation with a half-life of 30-103 min. Additionally, BCPx-NO produces peroxynitrite (ONOO-) and singlet oxygen (1O2) under photoirradiation. To understand the mechanism of NO release and photolysis of the functional group under blue light, we prepared a small-molecule anthraquinone-based N-nitrosamine (NOD). The cellular investigation of the effect of spatiotemporally controlled ONOO- and 1O2 generation from the NO donor polymeric nanoparticles in a triple negative breast adenocarcinoma (MDA-MB-231) under visible light irradiation (white light, 5.83 mW/cm2; total dose 31.5 J/cm2) showed an IC50 of 0.6 mg/mL. The stimuli-responsive strategy using a photolabile water-soluble block copolymer employed to generate ROS and RNS in a biological setting widens the horizon for their potential in cancer therapy.

A transient vesicular glue for amplification and temporal regulation of biocatalytic reaction networks.

Regulation of enzyme activity and biocatalytic cascades on compartmentalized cellular components is key to the adaptation of cellular processes such as signal transduction and metabolism in response to varying external conditions. Synthetic molecular glues have enabled enzyme inhibition and regulation of protein-protein interactions. So far, all the molecular glue systems based on covalent interactions operated under steady-state conditions. To emulate dynamic biological processes under dissipative conditions, we introduce herein a transient supramolecular glue with a controllable lifetime. The transient system uses multivalent supramolecular interactions between guanidinium group-bearing surfactants and adenosine triphosphate (ATP), resulting in bilayer vesicle structures. Unlike the conventional chemical agents for dissipative assemblies, ATP here plays the dual role of providing a structural component for the assembly as well as presenting active functional groups to "glue" enzymes on the surface. While gluing of the enzymes on the vesicles achieves augmented catalysis, oscillation of ATP concentration allows temporal control of the catalytic activities similar to the dissipative cellular nanoreactors. We further demonstrate temporal upregulation and control of complex biocatalytic reaction networks on the vesicles. Altogether, the temporal activation of biocatalytic cascades on the dissipative vesicular glue presents an adaptable and dynamic system emulating heterogeneous cellular processes, opening up avenues for effective protocell construction and therapeutic interventions.

Chemically routed interpore molecular diffusion in metal-organic framework thin films.

Transport diffusivity of molecules in a porous solid is constricted by the rate at which molecules move from one pore to the other, along the concentration gradient, i.e. by following Fickian diffusion. In heterogeneous porous materials, i.e. in the presence of pores of different sizes and chemical environments, diffusion rate and directionality remain tricky to estimate and adjust. In such a porous system, we have realized that molecular diffusion direction can be orthogonal to the concentration gradient. To experimentally determine this complex diffusion rate dependency and get insight of the microscopic diffusion pathway, we have designed a model nanoporous structure, metal-organic framework (MOF). In this model two chemically and geometrically distinct pore windows are spatially oriented by an epitaxial, layer-by-layer growth method. The specific design of the nanoporous channels and quantitative mass uptake rate measurements have indicated that the mass uptake is governed by the interpore diffusion along the direction orthogonal to the concentration gradient. This revelation allows chemically carving the nanopores, and accelerating the interpore diffusion and kinetic diffusion selectivity.

Two-Dimensional Ultrathin CeVO4 Nanozyme: Fabricated through Non-Oxidic Material.

In recent years, the synthesis of materials in lower dimensions, like two-dimensional (2D) or ultrathin crystals, with distinctive characteristics has attracted substantial scientific attention. The mixed transition metal oxides (MTMOs) nanomaterials are the promising group of materials, which have been extensively utilized for various potential applications. Most of the MTMOs were explored as three-dimensional (3D) nanospheres, nanoparticles, one-dimensional (1D) nanorods, and nanotubes. However, these materials are not well explored in 2D morphology because of the difficulties in removing tightly woven thin oxide layers or exfoliations of 2D oxide layers, which hinder the exfoliation of beneficial features of MTMO. Here, through the exfoliation via Li+ ion intercalation and subsequent oxidation of CeVS3 under hydrothermal condition, we have demonstrated a novel synthetic route for the fabrication of 2D ultrathin CeVO4 NS. The as-synthesized CeVO4 NS exhibit adequate stability and activity in a harsh reaction environment, which gives excellent peroxidase-mimicking activity with a K M value of 0.04 mM, noticeably better than natural peroxidase and previously reported CeVO4 nanoparticles. We have also used this enzyme mimic activity for the efficient detection of biomolecules like glutathione with a LOD of 53 nM.

An adaptive fuzzy logic control technique for LVRT enhancement of a grid-integrated DFIG-based wind energy conversion system.

The fast improvement of wind energy conversion technology with optimization algorithms has recently received a lot of attention. However, their slow convergence speed, huge computational load, and low efficiency are the main drawbacks and to improve these disadvantages, a new adaptive fuzzy logic controller strategy is proposed to enhance the low voltage ride-through of the grid-connected doubly fed induction generator during severe grid faults. The rotor side converter and the grid side converter are controlled using an adaptive fuzzy logic controller topology under cascaded structure to improve the performance. The novel application of the 'generalized variable step-size diffusion continuous mixed p-norm' adaptive filtering algorithm is proposed to modify the calibrating factors of the fuzzy logic controllers at a rapid convergence speed with low normalized misalignment error. The proposed adaptive algorithm-based fuzzy logic controller has a better low voltage ride-through improvement capability than that of using the particle swarm optimization-based proportional-integral controller during severe grid disturbances. The convergence speed of the proposed adaptive filtering algorithm is compared to that of existing algorithms such as least mean fourth, least mean square, and continue mixed p-norm algorithms. In addition, a comparison is also made with different common optimization methods. The field-programmable gate array-based real-time experimental results are presented to validate the proposed adaptive control topology.

Separation of Branched Alkanes Feeds by a Synergistic Action of Zeolite and Metal-Organic Framework.

Zeolites and metal-organic frameworks (MOFs) are considered as "competitors" for new separation processes. The production of high-quality gasoline is currently achieved through the total isomerization process that separates pentane and hexane isomers while not reaching the ultimate goal of a research octane number (RON) higher than 92. This work demonstrates how a synergistic action of the zeolite 5A and the MIL-160(Al) MOF leads to a novel adsorptive process for octane upgrading of gasoline through an efficient separation of isomers. This innovative mixed-bed adsorbent strategy encompasses a thermodynamically driven separation of hexane isomers according to the degree of branching by MIL-160(Al) coupled to a steric rejection of linear isomers by the molecular sieve zeolite 5A. Their adsorptive separation ability is further evaluated under real conditions by sorption breakthrough and continuous cyclic experiments with a mixed bed of shaped adsorbents. Remarkably, at the industrially relevant temperature of 423 K, an ideal sorption hierarchy of low RON over high RON alkanes is achieved, i.e., n-hexane ≫ n-pentane ≫ 2-methylpentane > 3-methylpentane ⋙ 2,3-dimethylbutane > isopentane ≈ 2,2-dimethylbutane, together with a productivity of 1.14 mol dm-3 and a high RON of 92, which is a leap-forward compared with existing processes.

Succussed Serial Dilutions in Water Carry Solute Information via Solute-Specific Water Structures-A Theory Based on Quantum Electrodynamics.

Active ingredients are unlikely to be present in homeopathic dilutions that surpass the Avogadro limit. Yet responses of biological systems to these substances-chemically equivalent to water and indistinguishable from one another-are specific to the materials that are diluted away. This article addresses this challenging problem of homeopathy by identifying its underlying cause through a quantum electrodynamics-based "structural model" stated as: Succussed serial dilutions in water carry information about the solute via solute-specific water structures. The model is verifiable by our three-stranded set of experiments-nuclear magnetic resonance spectroscopy, anomalous dielectric dispersion, and atomic force microscopy. The results, some of which are presented here, directly or indirectly indicate that even extremely diluted solutions, devoid of any gross presence of the solutes, contain solute-reminiscent water structures. Apart from contributing to understanding high-dilution phenomena, these findings are expected to create an impact in the areas of medicine, pharmacopeia, and biology. Succussed aqueous dilutions acquire altered water structures with change of starting material: thus, their altered properties may be ascribed to these water structures, akin to allotropes of carbon. This theory justifies water structures as potential information carrier through succussed serial dilutions.

Can the position of the vertebral artery be predicted on a lateral view X-ray of the craniovertebral junction? A radiological anatomy study.

BACKGROUND: The most feared complication while inserting C2 screws is vertebral artery injury. This article proposes predicting the position of the vertebral artery on a true lateral X-ray of the axis vertebra from the background information acquired from the computed tomography (CT) scan utilizing fluoroscopy. METHODS: Spiral CT scans of 33 C2 vertebrae were performed utilizing a 16-slice CT scanner lateral X-rays of C2 were then obtained before and after painting the vertebral artery grooves with barium. The space available for transarticular and C2 pedicle screw insertion above the vertebral artery groove in the isthmus was then calculated as a ratio for both X-rays and CT scans. RESULTS: There was no statistically significant difference between the (mean) ratios calculated by CT scan and X-rays regarding the space available for transarticular and C2 pedicle screw insertion (left side: 0.3894 vs 0.3897; right side: 0.3892 vs 0.3925; P > 0.05). The Kappa test revealed that CT scan and X-ray findings were in agreement in majority of the bones (left side: n = 24, 72.7%, right side: n = 22, 73.3%; P < 0.05). CONCLUSION: A thorough understanding of a true lateral view X-ray based on background information extracted from three dimensional CT scans helps predict the highest point of the vertebral artery groove. This proves useful for placement of C2 transarticular and pedicle screws during regular "open" and "minimally invasive" spine surgery.

Heterometallic Metal-Organic Frameworks That Catalyze Two Different Reactions Sequentially.

A series of copper- and alkaline-earth-metal-based multidimensional metal-organic frameworks, {[CuMg(pdc)2(H2O)4]·2H2O}n (1), [CuCa(pdc)2]n (2), [CuSr(pdc)2(H2O)3]n (3), and {[CuBa(pdc)2(H2O)5]·H2O}n (4), where H2Pdc = pyridine-2,5-dicarboxylic acid, were hydrothermally synthesized and characterized. Two different metals act as the active center to catalyze two kinds of reactions, viz., olefin to its epoxide followed by epoxide ring opening to afford the corresponding vicinal diol in a sequential manner.

Development of intelligent instruments with embedded HTTP servers for control and data acquisition in a cryogenic setup--The hardware, firmware, and software implementation.

The power of Ethernet for control and automation technology is being largely understood by the automation industry in recent times. Ethernet with HTTP (Hypertext Transfer Protocol) is one of the most widely accepted communication standards today. Ethernet is best known for being able to control through internet from anywhere in the globe. The Ethernet interface with built-in on-chip embedded servers ensures global connections for crate-less model of control and data acquisition systems which have several advantages over traditional crate-based control architectures for slow applications. This architecture will completely eliminate the use of any extra PLC (Programmable Logic Controller) or similar control hardware in any automation network as the control functions are firmware coded inside intelligent meters itself. Here, we describe the indigenously built project of a cryogenic control system built for linear accelerator at Inter University Accelerator Centre, known as "CADS," which stands for "Complete Automation of Distribution System." CADS deals with complete hardware, firmware, and software implementation of the automated linac cryogenic distribution system using many Ethernet based embedded cryogenic instruments developed in-house. Each instrument works as an intelligent meter called device-server which has the control functions and control loops built inside the firmware itself. Dedicated meters with built-in servers were designed out of ARM (Acorn RISC (Reduced Instruction Set Computer) Machine) and ATMEL processors and COTS (Commercially Off-the-Shelf) SMD (Surface Mount Devices) components, with analog sensor front-end and a digital back-end web server implementing remote procedure call over HTTP for digital control and readout functions. At present, 24 instruments which run 58 embedded servers inside, each specific to a particular type of sensor-actuator combination for closed loop operations, are now deployed and distributed across control LAN (Local Area Network). A group of six categories of such instruments have been identified for all cryogenic applications required for linac operation which were designed to build this medium-scale cryogenic automation setup. These devices have special features like remote rebooters, daughter boards for PIDs (Proportional Integral Derivative), etc., to operate them remotely in radiation areas and also have emergency switches by which each device can be taken to emergency mode temporarily. Finally, all the data are monitored, logged, controlled, and analyzed online at a central control room which has a user-friendly control interface developed using LabVIEW(®). This paper discusses the overall hardware, firmware, software design, and implementation for the cryogenics setup.

Alkaline earth metal-based metal-organic framework: hydrothermal synthesis, X-ray structure and heterogeneously catalyzed Claisen-Schmidt reaction.

Two alkaline earth metal-based carboxylate systems, [Mg(HL)(H2O)2]n (1) and [Ca(H2L)2]n (2) (H3L = chelidamic acid) have been hydrothermally synthesized, and characterized by single-crystal X-ray diffraction, IR, elemental analysis, and thermo-gravimetric analysis. Compound 1 has a 2D structure incorporating two water molecules. The dehydrated species, 1a, generated from 1 by removal of the coordinated water, has been characterized by thermo-gravimetric analysis, IR, elemental analysis and variable temperature powder X-ray diffraction. Both 1 and its dehydrated species 1a catalyze the Claisen-Schmidt reaction under heterogeneous conditions, but 1a is a more effective catalyst under environmentally friendly conditions. The catalyst can readily be recovered and reused in successive cycles without detectable loss of activity. Compound 2 has a 3D structure and is thermally stable up to 540 °C, but is inactive catalytically.

A magnesium-based multifunctional metal-organic framework: synthesis, thermally induced structural variation, selective gas adsorption, photoluminescence and heterogeneous catalytic study.

Three magnesium based carboxylate framework systems were prepared through a temperature-dependent synthesis. The compounds were synthesized by a hydrothermal method and characterized by single crystal X-ray diffraction analysis. A stepwise increase in the temperature of the medium resulted a stepwise increase in the dimensionality of the network, ultimately leading to the formation of a new 2D layered alkaline earth metal-organic framework (MOF) compound, {[Mg2(HL)2(H2O)4]·H2O}n (1) (H3L = pyrazole-3,5-dicarboxylate). Compound 1 selectively adsorbs hydrogen (H2) (ca. 0.56 wt% at 77 K) over nitrogen at 1 atm and demonstrates a strong blue fluorescent emission band at 480 nm (λ(max)) upon excitation at 270 nm. Notably, the 2D framework compound efficiently catalyzes the aldol condensation reactions of various aromatic aldehydes with ketones in a heterogeneous medium under environmentally friendly conditions. The catalyst can be recycled and reused several times without any significant loss of activity.

Anchoring of palladium onto surface of porous metal-organic framework through post-synthesis modification and studies on Suzuki and Stille coupling reactions under heterogeneous condition.

An ecofriendly solid catalyst has been synthesized by anchoring palladium(II) into post synthetically modified metal organic framework IRMOF-3. The pore of IRMOF-3 was first modified with pyridine-2-aldehyde. The amine group of IRMOF-3 upon condensation with pyridine-2-aldehyde afforded a bidentate Schiff base moiety in the porous matrix. The Schiff base moieties were used to anchor palladium(II) ions. The prepared catalyst has been characterized by UV-vis, IR spectroscopy, X-ray powder diffraction, and nitrogen sorption measurements. Framework structure of the catalyst is not being destroyed in the multistep synthesis procedure as evidenced in X-ray powder diffraction studies. The catalyst has shown high activity toward the Suzuki and Stille cross-coupling reaction in 20% H2O/EtOH and EtOH medium, respectively, at 80 °C. The immobilized complex did not leach or decompose during the catalytic reactions, showing practical advantages over the homogeneous catalysis.

Porous magnesium carboxylate framework: synthesis, X-ray crystal structure, gas adsorption property and heterogeneous catalytic aldol condensation reaction.

A new three-dimensional alkaline-earth metal-organic framework (MOF) compound, [Mg(Pdc)(H(2)O)](n) (1) (H(2)Pdc = pyridine-2,5-dicarboxylic acid), has been synthesized and structurally characterized by single crystal X-ray diffraction analysis. Compound 1 features a 3D porous framework afforded by the Mg(2)-diad centers through formation of interconnected chair like structural motifs. A nitrogen adsorption study confirms the microporosity of compound 1 with a BET surface area of 211 ± 12 m(2) g(-1). Upon dehydration, the BET surface area of 1 is enhanced to a value of 463 ± 36 m(2) g(-1) due to removal of coordinated water molecule. After rehydration, the compound reverts to its original form as evidenced by powder X-ray diffraction and IR spectroscopic analysis and N(2) sorption measurement. Compound 1 retains its pore structure with a variable BET surface area in several cycles of dehydration and rehydration processes indicating robustness of the framework in [Mg(Pdc)(H(2)O)](n) (1). Compound 1 catalyzes the aldol condensation reactions of various aromatic aldehydes with acetone and cyclohexanone in heterogeneous conditions. Notably, the catalytic activity of the compound is enhanced upon dehydration. The catalyst can be recycled and reused several times without significant loss of activity.