# Chemistry

### Researchers have developed a material that can transform sewage water into safe drinking water within minutes

If there is one technology that the world needs now, it is the one that can convert salty seawater into pure and drinkable water in a matter of minutes. If the scientific community can achieve that, the water crisis will no longer be a major global concern. It will completely change the lives of the people in underdeveloped areas. Researchers have been working on this principle for a long time, and thankfully they have finally found a solution to this dilemma.
Nature.com

### The heating efficiency of magnetic nanoparticles under an alternating magnetic field

Hysteresis loss and relaxation loss are the two dominant heating mechanisms of magnetic nanoparticles (MNPs) in an alternating magnetic field (AMF). In magnetic induction hyperthermia, heating efficiency is one of the crucial factors. It is proposed that the MNPs with a dominant heating mechanism of relaxation loss will exhibit a higher heating efficiency. However, the relative experiments supporting the proposal is still absent due to the difficulty of obtaining the MNPs with the same components and similar morphology but different dominant heating mechanism. Here, the post-processing method of calcination is employed to change the cation distribution of the MNPs (Fe3O4 and Zn0.54Co0.46Cr0.6Fe1.4O4), so as to obtain the MNPs with similar morphology but different dominant heating mechanism. The magnetic heating experiments were conducted to examine the heating efficiency. The results suggest that the MNPs with relaxation loss have a higher heating efficiency under the investigated AMF.
SCIENCE
Phys.org

### Molecular-level design strategy could hold the key to boosting commercial hydrogen production

Our excessive consumption of fossil fuels is responsible for some of the major societal challenges we are facing, from climate change to pollution. Hydrogen is considered a green alternative to fossil fuels, and alkaline water electrolysis is proving an attractive technology for large-scale commercialization of hydrogen production. However, current industrial...
ENERGY INDUSTRY
Phys.org

### Exotic electronic effect found in 2D topological material

Jülich researchers have been able to demonstrate an exotic electronic state, so-called Fermi Arcs, for the first time in a 2D material. The surprising appearance of Fermi arcs in such a material provides a link between novel quantum materials and their respective potential applications in a new generation of spintronics and quantum computing. The results have recently been published in Nature Communications.
PHYSICS
Nature.com

### Quantum mechanics guided by simplicity

Dr Arieh Warshel, distinguished professor of chemistry at the University of Southern California and 2013 Nobel laureate in chemistry, discusses with Nature Computational Science past and current research, his Nobel Prize, and the benefits and challenges of using computational modeling in his work. You have full access to this article...
MATHEMATICS
Phys.org

### Solving stability problems of relevant graphene derivatives

In the last decades, a new synthetic approach has been developed, generally termed as "on-surface synthesis" that substantially departs from standard wet-chemistry. Instead of the three-dimensional space of solvents in the latter, the environment of the reactants in this new approach are well-defined two-dimensional solid surfaces that are typically held under vacuum conditions. These differences have allowed the successful synthesis of a great variety of molecular structures that could not be obtained by conventional means.
SCIENCE
Phys.org

### Researchers explain unique underlying atomic structure of PNCP metallic glass

Pd42.5Ni7.5Cu30P20 (PNCP) is considered the champion of bulk metallic glasses due to its glass-forming ability (GFA), yet the atomic configurations that lead to this property remain unknown. Recently an international team of researchers led by Prof. Shinya Hosokawa of the Kumamoto University, Japan analyzed the atomic configurations of PNCP, compared it with previous alloys, and found its characteristic configurations and the origin of its GFA. This can help engineers to create better metallic glasses.
SCIENCE
Phys.org

### Review of noble-gas spin amplification via spin-exchange collisions

This study was led by Prof. Xinhua Peng and Prof. Min Jiang who have been devoted to developing spin-based quantum technologies for the detection of weak magnetic fields for many years. The researchers used a vapor cell containing spatial overlapping nuclear spins of noble gas (e.g., xenon-129) and atomic spins...
PHYSICS
Nature.com

### Experimental and theoretical study of the effect of different functionalities of graphene oxide/polymer composites on selective CO capture

There is a constant need for versatile technologies to reduce the continuously increasing concentration of CO2 in the atmosphere, able to provide effective solutions under different conditions (temperature, pressure) and composition of the flue gas. In this work, a combination of graphene oxide (GO) and functionalized waterborne polymer particles was investigated, as versatile and promising candidates for CO2 capture application, with the aim to develop an easily scalable, inexpensive, and environmentally friendly CO2 capture technology. There are huge possibilities of different functional monomers that can be selected to functionalize the polymer particles and to provide CO2-philicity to the composite nanostructures. Density functional theory (DFT) was employed to gain a deeper understanding of the interactions of these complex composite materials with CO2 and N2 molecules, and to build a basis for efficient screening for functional monomers. Estimation of the binding energy between CO2 and a set of GO/polymer composites, comprising copolymers of methyl methacrylate, n-butyl acrylate, and different functional monomers, shows that it depends strongly on the polymer functionalities. In some cases, there is a lack of cooperative effect of GO. It is explained by a remarkably strong GO-polymer binding, which induced less effective CO2-polymer interactions. When compared with experimental results, in the cases when the nanocomposite structures presented similar textural properties, the same trends for selective CO2 capture over N2 were attained. Besides novel functional materials for CO2 capture and a deeper understanding of the interactions between CO2 molecules with various materials, this study additionally demonstrates that DFT calculations can be a shorter route toward the efficient selection of the best functionalization of the composite materials for selective CO2 capture.
SCIENCE
Nature.com

### Coexistence of two types of short-range order in Si"“Ge"“Sn medium-entropy alloys

Short-range chemical order (SRO) has been shown to play a decisive role in modulating a wide range of physical properties in medium-entropy alloys and high-entropy alloys. The enormous configurational space of these alloys implies multiple forms of SRO may exist, but such structural diversity has not been reported. Here, ab initio-based sampling reveals that Si"“Ge"“Sn medium-entropy alloys have two distinct forms of SRO, which carry different energies, distinct degrees of local ordering, and dissimilar electronic structures, and co-exist across a wide range of Si"“Ge"“Sn compositions. We rationalize the co-existence of two SROs through their virtual degeneracy of thermodynamic stability, due to a subtle balance in the change of enthalpy and configurational entropy upon transformation between the two SROs. Such co-existence of SROs suggests an inherent structural heterogeneity, a diffuse electronic structure, and a new route for band engineering in Si"“Ge"“Sn medium-entropy alloys. More generally, this study indicates possibility of the co-existence of multiple forms of SRO in medium- and high-entropy alloys.
SCIENCE
Nature.com

### Ni ions doped oxyflourophosphate glass as a triple ultraviolet"“visible"“near infrared broad bandpass optical filter

Research and development R&D about new materials that can be used as an optical filter, shortpass, bandpass, and longpass is still ongoing. So, in this context, the 50P2O5"“20ZnF2"“15MgF2"“15PbF2 doped different concentrations of NiO ranging from 0 up to 4Â mol% as a bandpass filter was prepared using the conventional melt annealing method. The formation of the amorphous essence was observed in the X-ray diffraction patterns. The role of Ni ions in the produced glass network was studied by density and Fourier Transform Infrared FTIR spectroscopy results, which showed that the Ni ions play a network modifier role. Thermal analysis results showed high thermal stability for the produced glasses. Electron paramagnetic resonance EPR spectra results clarified that the Ni3+ ions occupy an elongated octahedral $$\left( {g_{ \bot } > g_{\parallel } \approx 2} \right)$$. The measurements of AC conductivity, dielectric constant, and electric modulus were studied at different temperatures and frequencies. The ionic conduction dominates the conductivity at high temperatures, while the electronic dominates at low temperatures. The appearance of Ni3+ (confirmed by ESR) and Ni2+ were observed in the optical absorption spectra, also it was found that both of them occupy both tetrahedral and octahedral sites. Three distinguished bands in the UV (centered at 354Â nm), visible (centered at 620Â nm), and NIR (centered at 1074Â nm) regions appeared in the optical transmittance spectra, indicating the defining characteristic of the bandpass filter.
PHYSICS
earth.com

### Plastics may live an immortal life thanks to new techniques

All the proteins, carbohydrates and fats that we eat consist of polymers – very large molecules that are made up of smaller units or building blocks. These repeated small molecules are known as monomers and the function of our digestive system is to break down the large molecules into their small units so that they may be absorbed into our blood. Thereafter, these monomers are available in our bodies to be reassembled into our own protein, carbohydrate and fat polymers. Just like Lego blocks, the units are broken apart and then put back together again to produce something useful.
SCIENCE
Phys.org

### Researchers study sugar uptake mechanism of industrial microorganism

With the help of genetic manipulation and advanced biophysical tools, an international research team has gained unexpected insight into how a bacterium uptakes sugars derived from plant feedstock. Their findings were published on Sept. 7 in mBio. "Efficient sugar uptake is crucial for microbial cell factories, so sugar transporters are...
SCIENCE
Nature.com

### Circumventing the stability problems of graphene nanoribbon zigzag edges

Carbon nanostructures with zigzag edges exhibit unique properties-such as localized electronic states and spins-with exciting potential applications. Such nanostructures however are generally synthesized under vacuum because their zigzag edges are unstable under ambient conditions: a barrier that must be surmounted to achieve their scalable integration into devices for practical purposes. Here we show two chemical protection/deprotection strategies, demonstrated on labile, air-sensitive chiral graphene nanoribbons. Upon hydrogenation, the chiral graphene nanoribbons survive exposure to air, after which they are easily converted back to their original structure by annealing. We also approach the problem from another angle by synthesizing a form of the chiral graphene nanoribbons that is functionalized with ketone side groups. This oxidized form is chemically stable and can be converted to the pristine hydrocarbon form by hydrogenation and annealing. In both cases, the deprotected chiral graphene nanoribbons regain electronic properties similar to those of the pristine nanoribbons. We believe both approaches may be extended to other graphene nanoribbons and carbon-based nanostructures.
SCIENCE
Nature.com

### Specific ion selectivity with a reverse-selective mechanism

A cation-selective membrane containing hydrous manganese oxide nanoparticles exhibits specific phosphate ion selectivity. Ion-selective membranes are widely used in areas such as ion extraction, water desalination, and energy conversion. The ion selectivity mechanism mainly relies on electrostatic interaction, steric hindrance, and chemical affinity1. Usually, fixed charge groups on the membrane repel the co-ions and attract counter-ions based on the electrostatic interaction, realizing an anion"“cation separation2. For ions with the same charge, the cooperation of the electric effect, size-selective effect, and chemical affinity enables monovalent"“multivalent ion discrimination3,4. Recently, the growing interest in ion recovery (such as lithium and phosphate) has exposed the need for membranes capable of letting through specific ions. However, these ion-selective mechanisms cannot efficiently separate ions with similar ionic radii, ionic charge, and dehydration energy5. Now, writing in Nature Nanotechnology, Iddya et al. have reported a nanocomposite membrane that shows a new, reverse"“selective mechanism that realizes specific phosphate permeation6.
SCIENCE
Nature.com

### A computational perspective on the Nobel Prize

The contributions of the computational science community to Nobel Prizes in chemistry and physics take center stage in this month's Focus issue. Every year, as October approaches, excitement and speculation about the announcement of the newest Nobel laureates ripples through the scientific community. By spotlighting work that has had the "greatest benefit to humankind", the Nobel Prize never fails to inspire scientists in all fields, and to reignite a passion for research and scientific progress. For computational scientists, this inspiration can come in many forms, as the realm of possibilities for applying computational tools continues to grow.
SCIENCE
Nature.com

### Natural glass alteration under a hyperalkaline condition for about 4000Â years

Silicate glasses are durable materials in our daily life, but corrosion rate accelerates under alkaline aqueous environment. Such situation has raised concerns, for example, in nuclear waste disposal where vitrified wastes encounter to alkaline leachate from surrounding concrete materials. Here we report volcanic glass example surviving with a hyperalkaline groundwater (pH"‰>"‰11) and high flow rate for about 4000Â years. The tiny glass fragments were extracted from the volcanic ash layer sandwiched between ultramafic sediments using microanalytical techniques. Sharp elemental distributions at the glass surface, where amorphous-like smectite precursors and crystalline smectites coexist, suggest the corrosion by an interface-coupled dissolution"“precipitation mechanism rather than inter-diffusion. The corrosion rate was maintained at, the minimum, 2.5 orders of magnitude less than the rate observed for fresh glass, even in the presence of Fe and Mg that might have consumed Si through the silicate precipitation.
SCIENCE
Nature.com

### A collective effort for building DFT

Dr Lu Sham, Distinguished Professor Emeritus of Physics at the University of California, San Diego, talks with Nature Computational Science about his current research, the density functional theory (DFT) work that was recognized by the 1998 Nobel Prize in Chemistry - awarded to his co-author Dr Walter Kohn - and where he thinks the field is heading.
SCIENCE

### 3D metal complexes could be the answer to overcoming fungal drug-resistance

Metal compounds could be the answer to the growing problem of drug-resistant fungal infections, according to new research published in the American Chemical Society on Sept .23. The compounds could help develop much-needed antifungal drugs-particularly for immunocompromised patients susceptible to fungal infections. The study led by University of Queensland researchers...
SCIENCE
Nature.com

### Controlled transitions between metastable states of 2D magnetocapillary crystals

Magnetocapillary interactions between particles allow to self-assemble floating crystals along liquid interfaces. For a fixed number of particles, different states possessing different symmetrical features, known as metastable states, coexist. In this paper, we demonstrate how to trigger the transition from one state to another, either by rearranging the crystal, or by controlling its growth. First, we show that externally controlled magnetic fields can squeeze the entire crystal to induce structural modifications, that upon relaxation can lead to a modified state. Second, we propose localized laser-induced thermocapillary flows that can be used to guide new particles towards an existing crystal in a desired direction, thus favoring a particular resulting state. The control of the formation of metastable states is a key ingredient to functionalize such assemblies, paving the way to self-assembled microrobots.
PHYSICS