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Category: materials – Page 17

Thermodynamics revisited: Study solves 120-year-old problem and corrects one of Einstein’s ideas

The concatenation of both ideas allows us to conclude that entropy exchanges tend to zero when the temperature tends to zero (which is Nernst’s theorem) and that absolute zero is inaccessible.

Martin-Olalla points out that a fundamental problem in thermodynamics is to distinguish the sensation of temperature, the sensations of hot and cold, from the abstract concept of temperature as a physical quantity. In the discussion between Nernst and Einstein, temperature was merely an empirical parameter: the absolute zero condition was represented by the condition that the pressure or volume of a gas became close to zero.

Formally, the second principle of thermodynamics provides a more concrete idea of the natural zero of temperature. The idea is not related to any sensation, but to that engine imagined by Nernst but which has to be virtual. This radically changes the approach to the proof of the theorem.

Next leap in mode-locked lasers: Tunable pulse duration in ultranarrow bandwidth

Lasers have widespread applications as a light source in a variety of fields, including manufacturing, medicine, high-speed communications, electronics, and scientific research.

In recent years, the demand for lasers with increased control over their output has grown significantly. In particular, ultranarrow mode-locked lasers, which can produce extremely short laser pulses (short bursts of light) ranging from picoseconds to nanoseconds, have received considerable attention. Such are extremely beneficial for many applications—from diamond cutting to semiconductor manufacture. However, these applications can be further improved with the incorporation of lasers with tunable pulse duration.

A laser works by reflecting light back and forth between a highly reflective and a selective reflective mirror inside a cavity, and then amplifying it using a material called the gain medium. Conventional continuous-wave lasers emit a continuous beam of light waves (modes) with different wavelengths and random phases.

Nanoscale phonon dynamics in self-assembled nanoparticle lattices

The realization and phonon imaging of nanoscale mechanical metamaterials has remained challenging. Here the authors resolve the phonon dynamics and band structures of five different self-assembled nanoparticle lattices, revealing the role of nanoscale colloidal interactions in modulating the lattice properties.

What is uranium enrichment and how is it used for nuclear bombs? A scientist explains

Late last week, Israel targeted three of Iran’s key nuclear facilities—Natanz, Isfahan and Fordow, killing several Iranian nuclear scientists. The facilities are heavily fortified and largely underground, and there are conflicting reports of how much damage has been done.

Natanz and Fordow are Iran’s uranium enrichment sites, and Isfahan provides the raw materials, so any damage to these sites would limit Iran’s ability to produce .

But what exactly is and why does it raise concerns?

Artificial light in big cities is extending the growing season of urban plants, satellite observations show

Artificial light may be lengthening the growing season in urban environments by as much as 3 weeks compared to rural areas, according to an analysis of satellite data from 428 urban centers in the Northern Hemisphere over 7 years, published in Nature Cities.

Rapid urbanization is leading to hotter and brighter cities. More specifically, buildings and concrete absorb and radiate heat, causing urban heat islands, in which urban areas have higher atmospheric temperatures throughout the day and night compared to their surroundings. Likewise, the amount of artificial at night has increased by 10% in cities within the past decade.

Light and temperature also largely regulate plant growing seasons. For example, increased lighting and temperature cause trees in cities to bud and flower earlier in the spring and change color later in the autumn than trees in rural surroundings. However, research has not thoroughly studied the magnitude of their individual or combined impacts.

Zoomcar discloses security breach impacting 8.4 million users

Zoomcar Holdings (Zoomcar) has disclosed that unauthorized accessed its system led to a data breach impacting 8.4 million users.

The incident was detected on June 9, after a threat actor emailed company employees alerting them of a cyberattack.

Although there has been no material disruption to services, the company’s internal investigation confirmed that sensitive data belonging to a subset of its customers has been compromised.

Scientists make mind-blowing discovery after studying material that only exists exists for billionths of a second: ‘Previously unimaginable’

Scientists have made liquid carbon in a lab for the first time, Interesting Engineering reported.

Liquid carbon was thought to be impossible to study under normal conditions. The material only exists for billionths of a second under extreme pressure and temperatures of about 4,500 degrees Celsius, making this record-breaking technology limitless in its potential.

Nuclear fusion, combining light atomic nuclei to release massive amounts of clean energy, has long been considered the holy grail of power generation. Fusion could change society by providing unlimited electricity without radioactive waste, helping cities, individuals, and companies save money compared to resource-intensive traditional energy methods.

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