Recent Advances in Direct Synthesis of Value-Added Aromatic Chemicals from Syngas by Cascade Reactions over Bifunctional Catalysts.

Value-added aromatic monomers such as benzene, toluene, and xylenes (BTX) are very important building-block chemicals for the production of plastics, polymers, solvents, pesticides, dyes, and adhesives. Syngas-to-aromatics (STA) is a very promising approach for the synthesis of aromatic monomers, and is catalyzed via bifunctional catalysts in a single reactor, wherein methanol/dimethyl ether and/or olefins intermediates formed from syngas on metal components are converted into aromatic monomers exclusively on the HZSM-5 by cascade reactions. Since an optimal Fischer-Tropsch synthesis (FTS) temperature of Fe-based catalysts is very close to an aromatization temperature of HZSM-5, Fe-based catalysts have been frequently used/modified for the synthesis of aromatic monomers from hydrogenation of carbon oxides (CO and CO2 ). The nature of metal components and amounts of Brönsted acid sites on HZSM-5, and their mesoporosity and intimacy, significantly alter the selectivity for aromatics by tuning BTX distibution and catalyst stability. Although many developments have been achieved regarding the STA process in recent years, no reviews have been published in this flourishing research area over the last two decades. Here, the recent advances and forthcoming challenges in the progress of syngas (CO+H2 ) chemistry and hydrogenation of CO2 toward the value-added aromatic monomers through cascade reactions are highlighted.

Differences in DNA Probe-Mediated Aggregation Behavior of Gold Nanomaterials Based on Their Geometric Appearance.

Nanoparticles are used extensively to detect nucleic acid biomarkers due to their analytical applicability and sensitivity. Systems employing the surface plasmon resonance of gold nanomaterials are overwhelmingly considered to be candidates. The aggregation of gold nanomaterials mediated by the hybridization of target DNA at the interface causes a change in the surface plasmon resonance inherent in gold nanomaterials. Such changes can be measured by spectroscopy or even visualized by the naked eye, enabling effective and positive detection. The optical properties of gold nanoparticles are affected by their shape. The geometric appearance of the nanoparticles also affects their colloidal stability and aggregation behavior. In this study, we examined the effect of the geometric appearance of gold nanomaterials on DNA-mediated aggregation behavior through comparative experiments. Experimental and theoretical methods were used concurrently to derive accurate results and to support the hypotheses. Coarse-grained molecular dynamics simulations were performed with a large-scale atomic/molecular massively parallel simulator to understand the aggregation of nanoparticles with the same surface area and various aspect ratios. As a result, we confirmed that the aggregation sensitivity of nanoparticles was affected by the shape of the contact point with the gold nanomaterials. This study demonstrates that the design of a detection system should be accompanied by an in-depth review of the morphology of the nanoparticle.

Aqueous Phase Synthesis of 5-Hydroxymethylfurfural from Glucose over Large Pore Mesoporous Zirconium Phosphates: Effect of Calcination Temperature.

For a solid acid-catalyzed dehydration of biomass-derived carbohydrates into useful furan derivatives, a suitable porous solid acid catalyst having an optimum acidic density and its strength is required to avoid cascade reactions in biomass conversion processes. A large-pore mesoporous zirconium phosphate (m-ZrP) was prepared hydrothermally using P123 as a template in water solvent, which resulted in a higher pore diameter (>9 nm) having wormhole-like pore structures with balanced Lewis (L) to Brönsted (B) acid sites. The effects of calcination temperature (500-800 °C) on the textural, acidic/basic, and structural properties of the m-ZrP with its catalytic performance for glucose dehydration to 5-hydroxymethylfurfural (HMF) were investigated in a pure water media as a green and sustainable alternative solvent. The larger number of L and B acid sites and basic sites with their appropriate strengths were clearly related with a better catalytic performance in terms of glucose conversion and HMF yield. The strong L acid and basic sites in the m-ZrP efficiently promoted the glucose isomerization to fructose, which dehydrated exclusively on the weak B acid sites resulting in a maximum conversion of glucose (83.8%) and HMF yield (46.6%). The adjusted acidic and basic sites with large mesopore sizes make the m-ZrP yield a higher reaction rate (2.78 mmol gcat -1 h-1) and turnover frequency (11.68/h) for conversion of glucose to HMF, which showed higher catalytic activity than those of a small-pore m-ZrP and other mesoporous heterogeneous and homogeneous acid catalysts.

Microtopography-Guided Conductive Patterns of Liquid-Driven Graphene Nanoplatelet Networks for Stretchable and Skin-Conformal Sensor Array.

Flexible thin-film sensors have been developed for practical uses in invasive or noninvasive cost-effective healthcare devices, which requires high sensitivity, stretchability, biocompatibility, skin/organ-conformity, and often transparency. Graphene nanoplatelets can be spontaneously assembled into transparent and conductive ultrathin coatings on micropatterned surfaces or planar substrates via a convective Marangoni force in a highly controlled manner. Based on this versatile graphene assembled film preparation, a thin, stretchable and skin-conformal sensor array (144 pixels) is fabricated having microtopography-guided, graphene-based, conductive patterns embedded without any complicated processes. The electrically controlled sensor array for mapping spatial distributions (144 pixels) shows high sensitivity (maximum gauge factor ≈1697), skin-like stretchability (<48%), high cyclic stability or durability (over 105 cycles), and the signal amplification (≈5.25 times) via structure-assisted intimate-contacts between the device and rough skin. Furthermore, given the thin-film programmable architecture and mechanical deformability of the sensor, a human skin-conformal sensor is demonstrated with a wireless transmitter for expeditious diagnosis of cardiovascular and cardiac illnesses, which is capable of monitoring various amplified pulse-waveforms and evolved into a mechanical/thermal-sensitive electric rubber-balloon and an electronic blood-vessel. The microtopography-guided and self-assembled conductive patterns offer highly promising methodology and tool for next-generation biomedical devices and various flexible/stretchable (wearable) devices.

Methyl Acetate Synthesis by Esterification on the Modified Ferrierite: Correlation of Acid Sites Measured by Pyridine IR and NH3-TPD for Steady-State Activity.

The amounts of Brønsted acid sites on K, P, and Zr-modified microporous Ferrierite zeolite were investigated through pyridine FT-IR and NH3-TPD analyses. P-modified Ferrierite showed a superior catalytic activity for methyl acetate synthesis by esterification of methanol and acetic acid. The catalytic activity at steady-state with the acidic properties of as-prepared catalysts was well correlated with the results of pyridine FT-IR (intensity ratio of Brønsted acid sites to total acid sites) compared with that of NH3-TPD. The results can suggest the proper and simple method to estimate the esterification activity at steady-state using the measured acid sites on the as-prepared zeolites.

Ordered mesoporous CoMOx (M = Al or Zr) mixed oxides for Fischer-Tropsch synthesis.

A superior structural stability of the ordered mesoporous CoMOx synthesized by using the KIT-6 template was observed under Fischer-Tropsch reaction conditions. The enhanced stability was attributed to a strong interaction of the irreducible metal oxides with the mesoporous Co3O4 by forming Co3O4-ZrO2 (or Co3O4-Al2O3), which resulted in showing a stable activity.

A Fluorescent Tile DNA Diagnocode System for In Situ Rapid and Selective Diagnosis of Cytosolic RNA Cancer Markers.

Accurate cancer diagnosis often requires extraction and purification of genetic materials from cells, and sophisticated instrumentations that follow. Otherwise in order to directly treat the diagnostic materials to cells, multiple steps to optimize dose concentration and treatment time are necessary due to diversity in cellular behaviors. These processes may offer high precision but hinder fast analysis of cancer, especially in clinical situations that need rapid detection and characterization of cancer. Here we present a novel fluorescent tile DNA nanostructure delivered to cancer cytosol by employing nanoparticle technology. Its structural anisotropicity offers easy manipulation for multifunctionalities, enabling the novel DNA nanostructure to detect intracellular cancer RNA markers with high specificity within 30 minutes post treatment, while the nanoparticle property bypasses the requirement of treatment optimization, effectively reducing the complexity of applying the system for cancer diagnosis. Altogether, the system offers a precise and rapid detection of cancer, suggesting the future use in the clinical fields.

Pulmonary Pneumatocele in a Pneumonia Patient Infected with Extended-Spectrum ß-Lactamase Producing Proteus mirabilis.

Pulmonary pneumatoceles are air-filled thin-walled spaces within the lung and are rare in adult cases of pneumonia. We report the case of a 74-year-old male who was admitted with a cough and sputum production. He had been treated with oral dexamethasone since a brain tumorectomy 6 months prior. Contrast-enhanced computed tomography (CT) of the chest revealed a large pneumatocele in the right middle lobe and peripheral pneumonic consolidation. Bronchoalveolar lavage was performed; cultures identified extended-spectrum ß-lactamase (ESBL) producing Proteus mirabilis. A 4-week course of intravenous ertapenem was administered, and the pneumatocele with pneumonia resolved on follow-up chest CT. To the best of our knowledge, this is the first reported case of pulmonary pneumatocele caused by ESBL-producing P. mirabilis associated with pneumonia.

Modified Nano-Perovskite Catalysts for the Steam and CO2 Reforming of Methane.

This paper describes the synthesis and characterization of La0.8Sr0.2NiO3 nano-perovskite type catalyst for steam-CO2 reforming (SCR) and CO2 reforming (DR) of methane. Effect of gelation agents such as PVA, EDTA and PAA on nano-perovskite structures was investigated. XRD, H2-TPR and FT-IR analysis were used to characterize the prepared catalysts. The catalytic reaction was performed in a fixed bed reactor system at 1 atm and 800 °C. The feed ratio of CH4:H2O:CO2 as reactants was adjusted according to the SCR and DR reactions. As a result, CH4 and CO2 conversions of PVA agent catalyst were higher than that of PAA and EDTA agent catalyst for DR reaction because the PVA agent catalyst had a well-established perovskite, a high absorption, a high reducibility. However, the PAA agent catalyst had a higher reactivity due to its high interaction of catalysts for SCR of methane due to its strong interaction of catalysts.

A superhydrophobic layer formed by fluoro-derivative-treated gold sheets on grown-up zinc oxide nanoparticles for a spherical DNA hydrogel.

A facile deposition process was developed for the fabrication of a new superhydrophobic layer composed of an underlying zinc oxide nanoparticle support and a gold top layer doped with the hydrophobic chemical, heptadecafluoro-1-decanethiol (HDFT). The resulting microscaled and spherical DNA-based hydrogels could serve as a platform for pseudo-nucleus mimics.

Efficient utilization of greenhouse gas in a gas-to-liquids process combined with carbon dioxide reforming of methane.

A process model for a gas-to-liquids (GTL) process mainly producing Fischer-Tropsch (FT) synthetic oils has been developed to assess the effects of reforming methods, recycle ratio of unreacted syngas mixture on the process efficiency and the greenhouse gas (GHG) emission. The reforming unit of our study is composed of both steam reforming of methane (SRM) and carbon dioxide reforming of methane (CDR) to form syngas, which gives composition flexibility, reduction in GHG emission, and higher cost-competitiveness. With recycling, it is found that zero emission of CO(2) from the process can be realized and the required amount of natural gas (NG) can be significantly reduced. This GTL process model has been built by using Aspen Plus software, and it is mainly composed of a feeding unit, a reforming unit, an FT synthesis unit, several separation units and a recycling unit. The composition flexibility of the syngas mixture due to the two different types of reforming reactions raises an issue that in order to attain the optimized feed composition of FT synthesis the amount of flow rate of each component in the fresh feed mixture should be determined considering the effects of the recycle and its split ratio. In the FT synthesis unit, the 15 representative reactions for the chain growth and water gas shift on the cobalt-based catalyst are considered. After FT synthesis, the unreacted syngas mixture is recycled to the reforming unit or the FT synthesis unit or both to enhance process efficiency. The effect of the split ratio, the recycle flow rate to the FT reactor over the recycle flow rate to the reforming unit, on the efficiency of the process was also investigated. This work shows that greater recycle to the reforming unit is less effective than that to the FT synthesis unit from the standpoint of the net heat efficiency of the process, since the reforming reactions are greatly endothermic and greater recycle to the reformer requires more energy.