There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

Metal-organic frameworks (MOFs) are an emerging class of porous materials with potential applications in gas storage, separations, catalysis, and chemical sensing. Despite numerous advantages, applications of many MOFs are ultimately limited by their stability under harsh conditions. Herein, the recent advances in the field of stable MOFs, covering the fundamental mechanisms of MOF stability, design, and synthesis of stable MOF architectures, and their latest applications are reviewed. First, key factors that affect MOF stability under certain chemical environments are introduced to guide the design of robust structures. This is followed by a short review of synthetic strategies of stable MOFs including modulated synthesis and postsynthetic modifications. Based on the fundamentals of MOF stability, stable MOFs are classified into two categories: high-valency metal-carboxylate frameworks and low-valency metal-azolate frameworks. Along this line, some representative stable MOFs are introduced, their structures are described, and their properties are briefly discussed. The expanded applications of stable MOFs in Lewis/Bronsted acid catalysis, redox catalysis, photocatalysis, electrocatalysis, gas storage, and sensing are highlighted. Overall, this review is expected to guide the design of stable MOFs by providing insights into existing structures, which could lead to the discovery and development of more advanced functional materials.

Stable Metal-Organic Frameworks: Design, Synthesis, and Applications.

http://csmres.co.uk/cs.public.upd/article-downloads/lynch.pdf

Protein-nanoparticle interactions

Atmospheric water is a resource equivalent to ~10% of all fresh water in lakes on Earth. However, an efficient process for capturing and delivering water from air, especially at low humidity levels (down to 20%), has not been developed. We report the design and demonstration of a device based on a porous metal-organic framework {MOF-801, [Zr6O4(OH)4(fumarate)6]} that captures water from the atmosphere at ambient conditions by using low-grade heat from natural sunlight at a flux of less than 1 sun (1 kilowatt per square meter). This device is capable of harvesting 2.8 liters of water per kilogram of MOF daily at relative humidity levels as low as 20% and requires no additional input of energy.

https://science.sciencemag.org/content/sci/early/2017/04/12/science.aam8743.full.pdf

Water harvesting from air with metal-organic frameworks powered by natural sunlight

Presence of hotspots in microprocessors requires localized dissipation of high heat fluxes. While typical background cooling solutions (e.g. air cooling with heat sinks/spreaders, heat pipes etc.) fail to address hotspots, aggressive fluidic cooling with liquid to vapor phase change can potentially meet this goal. In particular, we have been successful in cooling hotspots with a micro-fabricated device providing evaporative cooling. Fundamentally different from boiling, the device takes advantage of evaporation from the free surface of a very thin film of coolant enhanced by flow of dry sweeping gas. Heat transfer coefficients close to 0.1 MW/m2 K have already been demonstrated exceeding the performance of other contemporary phase change cooling solutions. This development can potentially play a very important role in designing effective thermal solutions for next generation microprocessors, with application in 3D stacked chips, cooling on-chip optical devices and power electronics, among others. In this paper, we briefly describe the various components constituting the device and the experimental procedure employed for testing the device under different operation conditions. In particular, we investigate the effect of flow configuration of the sweep gas on the overall performance of the system. Jet impingement of air is characterized by varying two operating parameters: (1) the separation between the jet’s nozzle and the evaporation surface, and (2) the inclination of the jet with respect to the evaporation surface (i.e., oblique jet impingement). The results from these experiments help elucidate the importance of these two factors in determining the overall performance of the device.Copyright © 2010 by ASME

Gas Assisted Thin-Film Evaporation for Hotspot Thermal Management

The influence of modifiers such as barium and lanthanum on the physical properties of γ-alumina has been studied. Calcination of the modified alumina at 723 K for 5 h does not result in any compound formation as evidenced from X.r.d. Ca. 8–9 wt% nickel was prepared by impregnation method using this modified alumina. Ba and La modifiers improve the reducibility of nickel and the metal area measured by hydrogen adsorption. It is presumed that the oxide layers over the surface of alumina prevent the interaction between nickel and γ-Al2O3, making more nickel available on the surface. The activity and turnover number (TON) for benzene hydrogenation vary directly with the available metal area, irrespective of the modifier.

Modification of γ-Alumina by Barium and Lanthanum, and the Consequential Effect on the Reducibility and Dispersibility of Nickel.

Selective Alkylation of Phenol to 2,6-Xylenol over Vanadia-Chromia Mixed Oxide Catalysts.

The influence of lithium modifier on the physical properties of alumina as well as on the reduction and dispersion of nickel oxide on alumina carrier is discussed. Lithium addition up to 2 wt % helps to improve the reducibility of Ni2+ ions, dispersion and metal area. It is explained on the basis of LiAl5O8 spinel formation which reduces the interaction between Ni2+ ions and alumina. A higher concentration of lithium (> 2 wt %) has a detrimental effect on reduction, dispersion and metal area. An electronic interaction, with the formation of Li–O–Ni, is proposed to explain this phenomenon. Benzene hydrogenation is used as a model reaction to compare the activity of various lithium modified nickel alumina catalysts. The effect of precalcination of the modified catalysts on reducibility is discussed.

Influence of Lithium on Reduction, Dispersion, and Hydrogenation Activity of Nickel on Alumina Catalysts.

A very high aniline alkylation activity under vapour-phase conditions by silica-supported vanadia catalyst is reported.

Shankar Narayanan

Papers

Gas Assisted Thin-Film Evaporation for Hotspot Thermal Management

Modification of γ-Alumina by Barium and Lanthanum, and the Consequential Effect on the Reducibility and Dispersibility of Nickel.

Selective Alkylation of Phenol to 2,6-Xylenol over Vanadia-Chromia Mixed Oxide Catalysts.

Influence of Lithium on Reduction, Dispersion, and Hydrogenation Activity of Nickel on Alumina Catalysts.

Enhanced Aniline Alkylation Activity of Silica‐Supported Vanadia Catalysts over Simple Oxides.