New understanding of the electrical properties of graphene nanoribbons (GRBs), when bounded with aromatic molecules, could have significant benefits in the development of chemosensors and personalised medicine.
Graphene is a modern wonder material possessing unique properties of strength, flexibility and conductivity whilst being abundant and remarkably cheap to produce, lending it to a multitude of useful applications – especially true when these 2D atom-thick sheets of carbon are split into narrow strips known as Graphene Nanoribbons (GNRs). New research published in EPJ Plus, authored by Kristiāns Čerņevičs, Michele Pizzochero, and Oleg V. Yazyev, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland, aims to better understand the electron transport properties of GNRs and how they are affected by bonding with aromatics. This is a key step in designing technology such chemosensors.
“Graphene nanoribbons – strips of graphene just few nanometres wide – are a new and exciting class of nanostructures that have emerged as potential building blocks for a wide variety of technological applications,” Čerņevičs says.
The team performed their investigation with the two forms of GNR , armchair and zigzag, which are categorised by the shape of the edges of the material. These properties are predominantly created by the process used to synthesise them. In addition to this, the EPFL team experimented p-polyphenyl and polyacene groups of increasing length.
“We have employed advanced computer simulations to find out how electrical conductivity of graphene nanoribbons is affected by chemical functionalisation with guest organic molecules that consist of chains composed of an increasing number of aromatic rings,” says Čerņevičs.
The team discovered that the conductance at energies matching the energy levels of the corresponding isolated molecule was reduced by one quantum, or left unaffected based on whether the number of aromatic rings possessed by the bound molecule was odd or even. The study shows this ‘even–odd effect’ originates from a subtle interplay between the electronic states of the guest molecule spatially localised on the binding sites and those of the host nanoribbon.
“Our findings demonstrate that the interaction of the guest organic molecules with the host graphene nanoribbon can be exploited to detect the ‘fingerprint’ of the guest aromatic molecule, and additionally offer a firm theoretical ground to understand this effect,” Čerņevičs concludes: “Overall, our work promotes the validity of graphene nanoribbons as promising candidates for next-generation chemosensing devices.”
These potentially wearable or implantable sensors will rely heavily on GRBs due to their electrical properties and could spearhead a personalised health revolution by tracking specific biomarkers in patients.
References: K. Čerņevičs, M. Pizzochero, O. V. Yazyev K. Čerņevičs, M. Pizzochero, O. V. Yazyev (2020), Even–odd conductance effect in graphene nanoribbons induced by edge functionalization with aromatic molecules: basis for novel chemosensors, Eur. Phys. J. Plus 134:681, DOI 10.1140/epjp/s13360-020-00696-y
Xbox Series X and Series S restock: Where to buy this week
Xboxes are hot commodities this holiday shopping season. Here’s how to find and buy an Xbox Series X and Series S this week amid high demand.
On Nov. 10, Microsoft’s $500 Xbox Series X and the $300 Xbox Series S hit the market with plenty of fanfare. Since the debut, stores have quickly sold out of available options and others are quickly purchased as companies restock physical and virtual shelves. That said, it’s been difficult for many individuals to purchase a new Xbox Series X and Series S. To assist, we’ve created a list of options to consider as stores receive shipments and restock shelves in the days ahead. We will update this article periodically with new information as items become available.
SEE: Guide to becoming a digital transformation champion (TechRepublic Premium)
Where to buy the Xbox Series X and Series S
Newegg is offering a bundle pack including a Series X with an Xbox core controller for $550. However, the bundle as well as the standalone model are unavailable. Those so inclined can register for an auto-notification to receive updates about future availability. Newegg is also offering an Xbox Series S bundle with an included Xbox core controller for $350. However, this bundle as well as the standalone Series S are both unavailable. The auto-notification option is also available for the Series S.
On the Microsoft website, people can click a button to “select a retailer” to view available Series X and Series S options. Standalone Xbox Series X models are currently out of stock at Best Buy, GameStop, Target, and Walmart, according to the pop-up on Microsoft’s site. Similarly, standalone Series S models were also out of stock at these retailers, per the Microsoft website.
We also tried to locate available Series S and Series X models on Best Buy, GameStop, Target, and Walmart directly.
Both the Series X and Series S are unavailable at Best Buy. This could change throughout the day as the retailer receives shipments and restocks shelves. As we reported earlier this week, Best Buy often restock at midnight and shoppers may consider checking the website closer to the time.
Both the Series X and the Series S digital edition are unavailable on GameStop. However, similar to other retailers, GameStop could restock shelves intermittently throughout the day. With such high demand, individuals may need to frequent a number of retailer websites and refresh the pages to potentially snag a model as they are made available.
On Thursday morning, Walmart Canada Gaming announced on Twitter that it had postponed an Xbox release originally scheduled for 12 pm Eastern. Both the Xbox Series X and Series S are unavailable on Walmart’s website. Again, this could change as the store receives shipments and restocks shelves. On Amazon, the Series X is currently unavailable. The Series S is available from the BuBuZon storefront with 65% positive ratings in the last year, based on 427 Amazon ratings.
Scientists discover why the heart slows down at night
A consensus more than 90-years-old on the mechanisms which regulate the day-night rhythm in heart rate has been fundamentally challenged by an international team of scientists from Manchester, London, Milan, Maastricht, Trondheim and Montpellier.
The vagus nerve – one of the nerves of the autonomic nervous system which supplies internal organs including the heart – has long been thought to be responsible for the slower night-time heart rates.
But the University of Manchester-led study on mice and rats discovered that the vagus nerve is unlikely to be directly involved and instead of the sinus node – the heart’s natural pacemaker – has its own clock, a biological clock.
The sinus node, they find, knows when it is night and slows the heart rate accordingly.
The British Heart Foundation-funded findings, published in Heart Rhythm, shine new light on this fundamental biological question of why the heart rate is slower at night and why dangerously slow heart rates – called bradyarrhythmias – can occur when we’re asleep.
The team behind the study demonstrated that changes in the ‘funny channel’ – also known as HCN4, a key protein that controls the heart rate – at different times of the day and night can explain the changes in heart rate.
The team found that blocking the funny channel with ivabradine, an angina treatment, removed the difference in heart rate between day and night.
The team found a role for the clock gene called BMAL1 as a regulator of the funny channel and this could one day lead to a treatment for dangerous bradyarrhythmias when we’re asleep.
Though the research was carried out in mice and rats, funny channels and clock genes play similar roles in all mammals – including humans – which is why the research has a universal significance.
Lead author Dr Alicia D’Souza, a British Heart Foundation Intermediate Fellow from The University of Manchester said: “The heart slows down when we sleep and there can even be pauses between heartbeats. Strangely, this is especially true in elite athletes. The longest documented pause is 15 seconds – a very long time to wait for your next heartbeat!
“For the very first time, we have tested an alternative hypothesis that there is a circadian rhythm in the intrinsic pacemaker of the heart – the sinus node.
“Our study shows that in mice, this is indeed the case and that explains why the heart rate is slower at night.
“These basic mechanisms of heart rate regulation are conserved in mammals – including humans – and therefore widely accepted concepts that are taught in schools may one day need to be revised.”
The sinus node – sometimes known as the sinoatrial node – generates electrical impulses which cause the heart to beat. It consists of a cluster of cells in the upper part of the right upper chamber of the heart.
Previous assumptions about the vagus nerve’s impact on the heart were based on a technique-called ‘heart rate variability’.
There are over 26,000 scientific papers based on heart rate variability published over 60 years. But the team’s previous British Heart Foundation-funded work demonstrated that heart rate variability is fundamentally flawed and says nothing about the vagus nerve.
In the present study the authors used a range of measurements to assess electrical activity and genes in the heart’s pacemaker. These included studying heart rhythm and activity levels and further exploration of ionic currents, proteins and regulatory proteins called transcription factors.
Cali Anderson, a British Heart Foundation-funded PhD student and co-author added: “It is well known that the resting heart rate in humans varies over 24 hours and is higher during the day than at night.
“But for over 90 years, the daily changes in our heart rate has been – and we believe over simplistically – assumed to be the result of a more active vagus nerve at night.
“In the future these findings could have important therapeutic potential in the way we are able to understand and treat heart rhythm disturbances.”
Dr Noel Faherty, Senior Research Advisor at the BHF, said: “This research challenges a near century-old consensus on how heart rate is regulated.
“A slower heart rate at night by itself is quite normal in most people, but understanding the mechanisms that govern the heart’s basic functions are crucial building blocks for tackling more complicated questions about heart rhythm disturbances.
“Worryingly, our ability to fund research like this in the future is threatened by the devastating fall in income caused by a coronavirus. It is more important than ever that the public continue to support our work so that we can continue to make progress in treating and preventing heart and circulatory disease in the UK.”
Source: University of Manchester
Amazon in Talks to Buy Podcast Publisher Wondery: Report
Internet giant Amazon is in talks to buy podcast publisher Wondery, which serves up hit audio shows Dr. Death and Serial, the Wall Street Journal reported on Wednesday.
Industry tracker Podtrac ranked Wondery as being the fourth most listened to podcast publisher in the US in November, with slightly more than 9 million people tuning in to audio programmes it hosts.
Podcasts have boomed in popularity, with people tuning in to hear compelling real or scripted stories as well as interviews.
Launched in 2016, Wondery has won audiences for shows such as Dr. Death, Dirty John, Business Wars, The Shrink Next Door, and Gladiator.
Wondery is seeking $300 million (roughly Rs. 2,200 crores) or more from a suitor, according to US media reports.
Amazon and Wondery both declined to comment on the report.
Word that Wondery is open to being bought comes as its chief executive Hernan Lopez defends himself against federal criminal charges over alleged bribes paid for broadcasting rights to major soccer tournaments while he worked as a Fox executive.
Amazon, which already offers some podcasts through its music app, is facing increased scrutiny from antitrust enforcers for its growing dominance over key sectors of the economy as it expands in retail and streaming media.
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