New solar cell may be most efficient in the world

July 13, 2017

Washington, Jul 13: Scientists have designed a new solar cell that converts direct sunlight to electricity with 44.5 per cent efficiency, and may potentially be the most efficient solar cell in the world.solar

The prototype integrates multiple cells stacked into a single device capable of capturing nearly all of the energy in the solar spectrum, researchers said.

The approach developed by researchers at George Washington University (GWU) in the US is different from the solar panels one might commonly see on rooftops or in fields.

The new device uses concentrator photovoltaic (CPV) panels that employ lenses to concentrate sunlight onto tiny, micro-scale solar cells.

Due to their small size - less than one millimetre square - solar cells utilising more sophisticated materials can be developed cost effectively, researchers said.

The stacked cell acts almost like a sieve for sunlight, with the specialised materials in each layer absorbing the energy of a specific set of wavelengths.

By the time the light is funnelled through the stack, just under half of the available energy has been converted into electricity. By comparison, the most common solar cell today converts only a quarter of the available energy into electricity.

"Around 99 per cent of the power contained in direct sunlight reaching the surface of Earth falls between wavelengths of 250 nanometres (nm) and 2,500 nm, but conventional materials for high-efficiency multi-junction solar cells cannot capture this entire spectral range," said Matthew Lumb, lead author of the study published in the journal Advanced Energy Materials.

"Our new device is able to unlock the energy stored in the long-wavelength photons, which are lost in conventional solar cells, and therefore provides a pathway to realising the ultimate multi-junction solar cell," said Lumb.

While scientists have worked towards more efficient solar cells for years, this approach has two novel aspects.

First, it uses a family of materials based on gallium antimonide (GaSb) substrates, which are usually found in applications for infra-red lasers and photodetectors. The novel GaSb-based solar cells are assembled into a stacked structure along with high efficiency solar cells grown on conventional substrates that capture shorter wavelength solar photons.

In addition, the stacking procedure uses a technique known as transfer-printing, which enables three dimensional assembly of these tiny devices with a high degree of precision.

This particular solar cell is very expensive, however researchers believe it was important to show the upper limit of what is possible in terms of efficiency.

Despite the current costs of the materials involved, the technique used to create the cells shows much promise, researchers said.

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Agencies
May 19,2020

Cybersecurity researchers on Monday warned of a Trojan malware campaign which is targeting India's co-operative banks using COVID-19 as a bait.

Seqrite, the enterprise arm of IT security firm Quick Heal Technologies, detected the new wave of Adwind Java Remote Access Trojan (RAT) campaign.

Researchers at Seqrite warned that if attackers are successful, they can take over the victim's device to steal sensitive data like SWIFT logins and customer details and move laterally to launch large scale cyberattacks and financial frauds.

According to the researchers, the Java RAT campaign starts with a spear-phishing email which claims to have originated from either the Reserve Bank of India or a nationalised bank.

The content of the email refers to COVID-19 guidelines or a financial transaction, with detailed information in an attachment, which is a zip file containing a JAR based malware.

Upon further investigation, researchers at Seqrite found that the JAR based malware is a Remote Access Trojan that can run on any machine which has Java runtime enabled and hence it can impact a variety of endpoints, irrespective of their base operating system.

Once the RAT is installed, the attacker can take over the victim's device, send commands from a remote machine, and spread laterally in the network.

In addition, this malware can also log keystrokes, capture screenshots, download additional payloads, and extract sensitive user information, Seqrite said, adding that such attack campaigns can effectively jeopardise the privacy and security of sensitive data at the co-operative banks and result in large scale attacks and financial frauds.

To prevent such attacks, users need to exercise ample caution and avoid opening attachments and clicking on web links in unsolicited emails.

Banks should also keep their operating systems updated and have a full-fledged security solution installed on all the devices, Seqrite advised.

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News Network
June 18,2020

Beijing, Jun 18:  Besides washing hands and wearing masks, it is also important to close the toilet lid before flushing to contain the spread of COVID-19, as per a new study.

According to a new study cited by The Washington Post, scientists who simulated toilet water and airflows, have found that flushing a toilet can generate a plume of virus-containing aerosol particles that is widespread and can linger in the air long enough to be inhaled by others. The novel coronavirus has been found in the faeces of COVID-19 patients, but it remains unknown whether such clouds could contain enough virus to infect a person.

"Flushing will lift the virus up from the toilet bowl," co-author Ji-Xiang Wang, who researches fluids at Yangzhou University in Yangzhou, China, said in an email. Wang stressed that bathroom users "need to close the lid first and then trigger the flushing process" and wash hands properly if the closure is not possible. As one flushes the toilet with the lids open, bits of faecal matter swish around so violently that they can be propelled into the air, become aerosolised and then settle on the surroundings.

Experts call it the "toilet plume".Age-old studies have been made to understand the potential for airborne transmission of infectious disease via sewage, and the toilet plume's role. Scientists who have seeded toilet bowls with bacteria and viruses have found contamination of seats, flush handles, bathroom floors and nearby surfaces. This is one reason we are told to wash our hands after visiting the toilet. Public bathrooms are well known to contribute to the spread of viruses that transmit via ingestion, such as the noroviruses that haunt cruise ships. However, their role in the transmission of respiratory viruses has not been established, said Charles P Gerba, a microbiologist at the University of Arizona."The risk is not zero, but how great a risk it is, we do not know. The big unknown is how much virus is infectious in the toilet when you flush it ... and how much virus does it take to cause an infection," said Gerba, who has studied the intersection of toilets and infectious disease for 45 years.

A study published in March in the journal Gastroenterology found significant amounts of coronavirus in the stool of patients and determined that viral RNA lasted in faeces even after the virus cleared from the patients` respiratory tracts. While another study in the journal Lancet found coronavirus in faeces up to a month after the illness had passed.

Scientists around the world are now studying sewage to track the spread of the virus. According to the researchers, the presence of the virus in excrement and the gastrointestinal tract raises the prospect of transmission via toilets, because many COVID-19 patients experience diarrhoea or vomiting.

A study of air samples in two hospitals in Wuhan, China found that although coronavirus aerosols in isolation wards and ventilated patient rooms were very low, "it was higher in the toilet areas used by the patients".The Centers for Disease Control and Prevention (CDC) says it remains "unclear whether the virus found in faeces may be capable of causing COVID-19," and "there has not been any confirmed report of the virus spreading from faeces to a person".For now, the CDC characterises the risk as low based on observations from previous outbreaks of other coronaviruses such as severe acute respiratory syndrome (SARS) and the Middle East respiratory syndrome (MERS). Wang decided to use computer models to simulate toilet plumes while isolating at home, as per Chinese government orders and thinking about how a fluids researcher "could contribute to the global fight against the virus".

Published in the journal Physics of Fluids, the study found that flushing of both single-inlet toilets, which push water into the bowl from one port, and annular-inlet toilets, which pour water into the bowl from the rim's surrounding edge with even greater energy, results in "massive upward transport of virus".

Particles can reach heights of more than three feet and float in the air for more than a minute, it found. The paper recommends not just lid-closing and hand-washing, it urges manufacturers to produce toilets that close and self-clean automatically. It also suggests that toilet-users should wipe down the seat. Gerba, however, said seats should not be a major concern.

Research has found that public and household toilet seats are typically the cleanest surfaces in restrooms, he said, probably because so many people already wipe them off before using them. Also, he said of SARS-CoV-2, the virus that causes COVID-19, "I don't think it's butt-borne, so I don`t think you have to worry."Gerba, who has been studying coronavirus transmission for two decades to investigate the role of a toilet flushing in a SARS outbreak stresses "flush and run" when using a public toilet without a lid. Gerba also said that people should wash hands well post-flushing and use hand sanitiser after leaving the restroom. "Choose well-ventilated bathrooms if possible and do not hang around the restroom in any case," added Gerba.

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Agencies
January 25,2020

New Delhi, Jan 25: The Patiala House court on Saturday started hearing a plea filed by the Nirbhaya convicts that alleged that the Tihar Jail administration have "not presented the papers on time".

The Public Prosecutor informed the court that Tihar Jail authorities have already supplied the relevant documents. He further informed that these are mere delaying tactics adopted by the convicts.

Advocate A.P. Singh, lawyer for three of the four death row convicts in the Nirbhaya gang-rape case had moved an application before the court seeking directions to the Tihar Jail authorities to supply him the relevant documents in order to exercise the remaining legal remedies available with the death row convicts -- Vinay Pawan and Akshay.

The Public Prosecutor also told the court that he spoke to the jail authorities over the phone and a report in this regard will be filed shortly as the jail officials were on their way to the court.

The judge demanded from the convicts lawyer to show what he has filed.

The convicts lawyer, A.P. Singh, said that he received some documents, but has still not been supplied with the personal diary of one of the convict -- Vinay Kumar Sharma and also the medical documents.

Judge then asked the lawyer to wait for until the report arrives form the Tihar Jail.

On this, the convicts lawyer said he was not questioning the intention of the jail. "I know the jail has been changed. It isn't there fault, too," he said.

The Public Prosecutor refuted the allegation saying that the defence counsel was trying to defeat the speed of law.

"We have supplied all the documents to the counsel. We have supplied all the documents except the painting and some other documents. We have nothing apart from that," public prosecutor said.

Singh, in his plea filed before the Patiala House Court sought urgent orders of the court in order to file a mercy petition of Vinay Sharma and in relation to requests for documents for convicts Vinay Sharma, Pawan Kumar Gupta and Akshay Kumar Singh.

He further said that the convicts undertook several steps to obtain relevant information necessary for filing the mercy petitions. In regular interval, the convicts requested the concerned authority to supply documents pertaining to their medical records from 2012 to 2015 and 2019-2020, records of cellular confinement, records of the amount earned in prison through labour, records of educational and reformative activities like Tihar Olympics and Painting, etc.

The Supreme court had recently dismissed the curative petition for the other two convicts -- Vinay Kumar Sharma (26) and Mukesh Singh (32).

The court had recently issued death warrant against the convicts and fixed 6 a.m. on February 1 as the date and time of execution of the death penalty.

The 23-year-old victim in the case was brutally gang raped and tortured on December 16, 2012, which later led to her death. All the six accused were arrested and charged with sexual assault and murder. One of the accused was a minor and appeared before a juvenile justice court, while another accused committed suicide in Tihar Jail.

Four of the convicts were sentenced to death by a trial court in September 2013, and the verdict was confirmed by the Delhi High Court in March 2014 and subsequently upheld by the Supreme Court in May 2017, which also dismissed their review petitions.

A Juvenile involved in the crime was convicted by a juvenile justice board and released from a reformation home after serving a three-year term.

Hearing in a different case, Chief Justice of India S.A. Bobde on Thursday said a condemned person cannot fight the death penalty endlessly and it was important for the capital punishment to reach its finality.

The death penalty, he noted, cannot be questioned at every turn by the convict.

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