Dr. Jeffery Huang Zhifeng, associate professor in the Department of Physics at HKBU, has developed a novel approach to manipulating the chirality of drug molecules.
Hong Kong Baptist University
Scientists from Hong Kong Baptist University (HKBU) have developed a novel technique that can produce pure therapeutic drugs without the associated side effects.
The approach, which uses a nanostructure fabrication device, can manipulate the chirality of drug molecules by controlling the direction a substrate is rotated within the device, thus eliminating the possible side effects that can arise when people take drugs containing molecules with the incorrect chirality.
Published in the scientific journal Nature Chemistry, the research findings pave the way towards the mass production of purer, cheaper, and safer drugs that can be made in a scalable and more environmentally-friendly way.
Control of molecular chirality improves drug safety
Many chemical molecules have two configurations, or chiral versions, that are mirror images of each other. While sharing the same molecular formula, the two chiral versions have different arrangements of their constituent atoms in space. The two versions of the molecules are characterized by left-handed and right-handed chiral configurations like human hands. Molecules with “left-handed” and “right-handed” chirality can have totally different biochemical effects.
More than half of the therapeutic drugs are made up of equal amounts of left-handed and right-handed chiral molecules, commonly known as “racemates;” one can cure specific diseases, but the other may have adverse effects. Separating and producing molecules with only the chiral arrangement (known as a single enantiomer) responsible for the therapeutic effects can help to produce drugs with improved safety and efficacy.
Macro-scale control of molecular chirality
In general, molecules have an extremely small size ranging from one-millionth to one hundred-thousandth of the diameter of a human hair. It is therefore extremely challenging to selectively produce one of the two chiral molecule versions using “macro-scale” control (i.e. the dimensional scale that can be seen using the naked eye and operated by hand). To produce single-enantiomer drugs, chemists have overwhelmingly used molecules called “chiral ligands” to effectively control the molecular chirality of drugs in the laboratory or industry at the molecular scale, a process called asymmetric synthesis. However, the existing technologies for producing single-enantiomer drugs are composed of complicated procedures, which are expensive and environmentally-unfriendly.
Dr. Jeffery Huang Zhifeng, associate professor in the Department of Physics at HKBU, and his research team devised a novel approach to manipulating molecular chirality through macro-scale control in collaboration with Sichuan University, Guangxi Medical University and the Southern University of Science and Technology. It involves mediating the manipulation with helical metal nanostructures (i.e. metal nanohelices) that are in the shape of a helical spring, and they have a characteristic size of one-thousandth of the diameter of a human hair.
Direction of rotation determines molecular chirality
The research team fabricated the metal nanohelices using a nanofabrication technique called glancing angle deposition (GLAD). Silver and copper were deposited onto a supporting substrate that was rotated clockwise and counterclockwise to fabricate the right-handed and left-handed metal nanohelices, respectively.
The research team then used ultraviolet light to induce a chemical reaction. This caused 2-anthracenecarboxylic acid (AC) molecules adsorbing on the metal nanohelices to undergo the chemical reaction and form chiral molecular products, which are similar to some chiral drugs. When AC was attached to the surface of the right-handed metal nanohelices and exposed to ultraviolet light, it preferentially produced “right-handed” chiral molecular products. By the same token, when AC was adsorbed on the surface of the left-handed metal nanohelices and exposed to ultraviolet light, it preferentially produced “left-handed” chiral molecular products. In other words, the chirality of the molecular product can be reliably determined by the chirality of the metal nanohelices, which is controlled by the direction of substrate rotation.
The research demonstrates that controlling the direction of substrate rotation at a macroscopic level can conveniently manipulate molecular chirality. This is an unprecedented application of the macro-scale method (through the control of the rotation direction of a 4-inch substrate holder) to manipulate chirality at the molecular-scale (chiral molecular products in the range of one-billionth of a meter).
Green approach to reducing drug side effects
“Our success in manipulating molecular chirality through macroscopic engineering allows the convenient synthesis of drugs in single-enantiomer forms with only left- or right-handedness. Hence, it will help get rid of the adverse, sometimes fatal, side effects of many therapeutic drugs,” said Huang.
The use of chiral ligands in the conventional method of asymmetric synthesis is inevitable, and it may cause pollution to enter the environment. In contrast, in this novel approach the metal nanohelices can be used repeatedly to produce single-enantiomer drugs without the use of chiral ligands. As a result, it paves the way towards the mass production of affordable therapeutic drugs that are made in a scalable manner with recyclable materials.
– This press release was originally published on the Hong Kong Baptist University website
When Is The Next Total Lunar Eclipse ‘Blood Moon?’ The Coming Once-In-430 Years ‘Twin’ Totality Will Be The Longest Until 2029 – Forbes
If you’re reading this having just seen the spectacular sight of the “Blood Moon” (or perhaps you didn’t because of cloud) it’s likely that there’s only one question on your mind: when’s the next one?
The next total lunar eclipse is on Monday, November 7 and into Tuesday, November 8, 2022. That’s in just 145 days! It will be best seen from west coast of North America, with Australia and southeast Asia also in a good position.
Like the events of May 15-16 it will also features an 84-minute totality (it’s actually four seconds longer). That’s highly unusual. According to Timeanddate.com, it’s the most balanced pair of lunar eclipses in 430 years.
November’s eclipse will be just as long as what North America just experienced, with lunar totality seeing the full “Frosty” or “Beaver” Moon turn a spectacular reddish color for 84 minutes.
That kind of duration of totality won’t be topped until a 102 minute totality on June 26, 2029.
A total lunar eclipse can be seen from any given location every 2.5 years, on average, and that plays out in the 2020s. The following total lunar eclipse is on March 13-14, 2025.
North America will once again get a good view, though it comes at a time of year when cloud will likely be a big problem.
It will almost be part of a “tetrad,” which is when four consecutive eclipse seasons—which are about six months apart—each contain a total lunar eclipse. However, the final event is a bit of a celestial letdown:
- March 14, 2025: Total lunar eclipse
- September 7, 2025: Total lunar eclipse
- March 3, 2026: Total lunar eclipse
- August 28, 2026: Partial lunar eclipse
However, with 93% of the Moon covered by the Earth’s shadow at the peak even that will be a sight to behold.
What is an ‘eclipse season?’
Every 173 days (six months), for between 31 and 37 days, the Moon is lined-up perfectly to intersect the ecliptic—the apparent path of the Sun through our daytime sky and the plane of Earth’s orbit around the Sun.
The result, of course, is a short season during which two—and occasionally three—solar and lunar eclipses can occur.
Disclaimer: I am the editor of WhenIsTheNextEclipse.com
Wishing you clear skies and wide eyes.
Starlink Group 4-13 | Falcon 9 Block 5 – Everyday Astronaut
Featured image credit: SpaceX
Lift Off Time
|May 13, 2022 – 22:07 UTC | 15:07 PDT|
|Starlink Group 4-13; the fifteenth launch to Starlink Shell 4|
|Falcon 9 Block 5, B1063-5; 108.20 day turnaround|
|Space Launch Complex 4 East (SLC-4E), Vandenberg Space Force Base, California, USA|
|~16,250 kg (~35,800 lb) (53 x 307 kg, plus dispenser)|
Where did the satellites go?
|Starlink Shell 4; 540 km circular low-Earth orbit (LEO); initial orbit: 315 x 305 km at 53.22°|
Did they attempt to recover the first stage?
Where did the first stage land?
|B1063 successfully landed 642 km downrange on Of Course I Still Love You
Tug: Debra C; Support: GO Quest
Did they attempt to recover the fairings?
|The fairing halves were recovered from the water ~654 km downrange by NRC Quest|
Were these fairings new?
|No, both fairing halves were flight proven|
This was the:
|– 153rd Falcon 9 launch
– 93rd Falcon 9 flight with a flight proven booster
– 97th re-flight of a booster
– 18th re-flight of a booster in 2022
– 119th booster landing
– 45th consecutive landing (a record)
– 19th launch for SpaceX in 2022
– 23rd SpaceX launch from SLC-4E
– 53rd orbital launch attempt of 2022
Where to watch
How Did It Go?
SpaceX’s Starlink Group 4-13 mission successfully launched 53 Starlink satellites atop a Falcon 9 rocket. The Falcon 9 lifted off from Space Launch Complex 4 East (SLC-4E), at the Vandenberg Space Force Base, in California, United States. Starlink Group 4-13 marked the 44th operational Starlink mission, boosting the total number of Starlink satellites launched to 2,547, of which 2,300 are in orbit around the Earth. Starlink Group 4-13 marked the 15th launch to the fourth Starlink shell; roughly 30 launches will be required to fill this shell.
Starlink is SpaceX’s internet communication satellite constellation. The low-Earth orbit constellation will deliver fast, low-latency internet service to locations where ground-based internet is unreliable, unavailable, or expensive. The first phase of the constellation consists of five orbital shells.
Starlink is currently available in certain regions, allowing anyone in approved regions to order or preorder. After 28 launches SpaceX achieved near-global coverage, but the constellation will not be complete until ~42,000 satellites are in orbit. Once Starlink is complete, the venture is expected to profit $30-50 billion annually. This profit will largely finance SpaceX’s ambitious Starship program, as well as Mars Base Alpha.
Each Starlink V1.5 satellite has a compact design and a mass of 307 kg. SpaceX developed a flat-panel design, allowing them to fit as many satellites as possible into the Falcon 9’s 5.2 meter wide payload fairing. Due to this flat design, SpaceX is able to fit up to 60 Starlink satellites and the payload dispenser into the second stage, while still being able to recover the first stage. This is near the recoverable payload capacity of the Falcon 9 to LEO, around 16 tonnes.
As small as each Starlink satellite is, each one is packed with high-tech communication and cost-saving technology. Each Starlink satellite is equipped with four phased array antennas, for high bandwidth and low-latency communication, and two parabolic antennas. The satellites also include a star tracker, which provides the satellite with attitude data, ensuring precision in broadband communication.
Each Starlink V1.5 satellite is also equipped with an inter-satellite laser communication system. This allows each satellite to communicate directly with other satellites, not having to go through ground stations. This reduces the number of ground stations needed, allowing coverage of the entire Earth’s surface, including the poles.
The Starlink satellites are also equipped with an autonomous collision avoidance system, which utilizes the US Department of Defense (DOD) debris tracking database to autonomously avoid collisions with other spacecraft and space junk.
To decrease costs, each satellite has a single solar panel, which simplifies the manufacturing process. To further cut costs, Starlink’s propulsion system, an ion thruster, uses krypton as fuel, instead of xenon. While the specific impulse (ISP) of krypton is significantly lower than xenon’s, it is far cheaper, which further decreases the satellite’s manufacturing cost.
Each Starlink satellite is equipped with the first Hall-effect krypton-powered ion thruster. This thruster is used for both ensuring the correct orbital position, as well as for orbit raising and orbit lowering. At the end of the satellite’s life, this thruster is used to deorbit the satellite.
A satellite constellation is a group of satellites that work in conjunction for a common purpose. Currently, SpaceX plans to form a network of 11,716 satellites; however, in 2019 SpaceX filed an application with the Federal Communication Commission (FCC) for permission to launch and operate an additional 30,000 satellites as part of phase 2 of Starlink. To put this number of satellites into perspective, this is roughly 20 times more satellites than were launched before 2019.
Of the initial ~12,000 satellites, ~4,400 would operate on the Ku and Ka bands, with the other ~7,600 operating on the V-Band.
Due to the vast number of Starlink satellites, many astronomers are concerned about their effect on the night sky. However, SpaceX is working with the astronomy community and implementing changes to the satellites to make them harder to see from the ground and less obtrusive to the night sky. SpaceX has changed how the satellites raise their orbits and, starting on Starlink V1.0 L9, added a sunshade to reduce light reflectivity. These changes have already significantly decreased the effect of Starlink on the night sky.
|Inclination (°)||Orbital Altitude (km)||Number of Satellites|
The first orbital shell of Starlink satellites consists of 1,584 satellites in a 53.0° 550 km low-Earth orbit. Shell 1 consists of 72 orbital planes, with 22 satellites in each plane. This shell is currently near complete, with occasional satellites being replaced. The first shell provides coverage between roughly 52° and -52° latitude (~80% of the Earth’s surface), and will not feature laser links until replacement satellites launch after 2021.
Starlink’s second shell will host 720 satellites in a 70° 570 km orbit. These satellites will significantly increase the coverage area, which will make the Starlink constellation cover around 94% of the globe. SpaceX will put 20 satellites in each of the 36 planes in the third shell. This shell is currently being filled, along with Shell 4.
Shell 3 will consist of 348 satellites in a 97.6° 560 km orbit. SpaceX deployed 10 laser link test satellites into this orbit on their Transporter-1 mission to test satellites in a polar orbit. SpaceX launched an additional three satellites to this shell on the Transporter-2 mission. On April 6, 2021, Gwynne Shotwell said that SpaceX will conduct regular polar Starlink launches in the summer, but this shell is now the lowest priority, and is expected to be the last filled. All satellites that will be deployed into this orbit will have inter-satellite laser link communication. Shell 4 will have six orbital planes with 58 satellites in each plane.
The fourth shell will consist of 1,584 satellites in a 540 km 53.2° LEO. This updated orbital configuration will slightly increase coverage area and will drastically increase the bandwidth of the constellation. This shell will also consist of 72 orbital planes with 22 satellites in each plane. This shell is currently being filled alongside Shell 2.
The final shell of Phase 1 of Starlink will host 172 satellites in another 97.6° 560 km low-Earth polar orbit. Shell 5 will also consist purely of satellites with laser communication links; however, unlike Shell 3, it will consist of four orbital planes with 43 satellites in each plane.
The sixth orbital shell of Starlink satellites is permitted to consist of 2,493 satellites in a 42° 335.9 km LEO. This large number of satellites will decrease latency and increase bandwidth for lower latitudes.
The seventh Starlink shell permits SpaceX to deploy 2,478 satellites into a 48° 340.8 km low-Earth orbit. These satellites will further decrease latency and increase bandwidth for lower latitudes.
The final shell of Starlink Phase 2 allows SpaceX to deploy 2,547 satellites in a 53° 345.6 km orbit.
SpaceX has until March of 2024 to complete half of phase 1 and must fully complete Phase 1 by March of 2027. Phase 2 must be half complete by November of 2024, and be finished by November of 2027. Failure to do so could result in SpaceX losing its dedicated frequency band.
What Is Falcon 9 Block 5?
The Falcon 9 Block 5 is SpaceX’s partially reusable two-stage medium-lift launch vehicle. The vehicle consists of a reusable first stage, an expendable second stage, and, when in payload configuration, a pair of reusable fairing halves.
The Falcon 9 first stage contains 9 Merlin 1D+ sea level engines. Each engine uses an open gas generator cycle and runs on RP-1 and liquid oxygen (LOx). Each engine produces 845 kN of thrust at sea level, with a specific impulse (ISP) of 285 seconds, and 934 kN in a vacuum with an ISP of 313 seconds. Due to the powerful nature of the engine, and the large amount of them, the Falcon 9 first stage is able to lose an engine right off the pad, or up to two later in flight, and be able to successfully place the payload into orbit.
The Merlin engines are ignited by triethylaluminum and triethylborane (TEA-TEB), which instantaneously burst into flames when mixed in the presence of oxygen. During static fire and launch the TEA-TEB is provided by the ground service equipment. However, as the Falcon 9 first stage is able to propulsively land, three of the Merlin engines (E1, E5, and E9) contain TEA-TEB canisters to relight for the boost back, reentry, and landing burns.
The Falcon 9 second stage is the only expendable part of the Falcon 9. It contains a singular MVacD engine that produces 992 kN of thrust and an ISP of 348 seconds. The second stage is capable of doing several burns, allowing the Falcon 9 to put payloads in several different orbits.
For missions with many burns and/or long coasts between burns, the second stage is able to be equipped with a mission extension package. When the second stage has this package it has a grey strip, which helps keep the RP-1 warm, an increased number of composite-overwrapped pressure vessels (COPVs) for pressurization control, and additional TEA-TEB.
Falcon 9 Booster
The booster that supported Starlink Group 4-13 is B1063. As the booster had supported 4 previous flights, its designation for Starlink Group 4-13 is B1063-5. This changed to B1063-6 upon successful landing.
|B1063’s missions||Launch Date (UTC)||Turnaround Time (Days)|
|Sentinel-6||November 21, 2020 17:17||N/A|
|Starlink V1.0 L28||May 26, 2021 18:59||186.07|
|DART||November 24, 2021 06:21||181.47|
|Starlink Group 4-11||February 25, 2022 17:12||62.45|
|Starlink Group 4-13||May 13, 2022 22:07||108.20|
Following stage separation, the Falcon 9 conducted two burns. These burns softly touched down the booster on SpaceX’s autonomous spaceport drone ship Of Course I Still Love You.
Falcon 9 Fairings
The Falcon 9’s fairing consists of two dissimilar reusable halves. The first half (the half that faces away from the transport erector) is called the active half, and houses the pneumatics for the separation system. The other fairing half is called the passive half. As the name implies, this half plays a purely passive role in the fairing separation process, as it relies on the pneumatics from the active half.
Both fairing halves are equipped with cold gas thrusters and a parafoil which are used to softly touch down the fairing half in the ocean. SpaceX used to attempt to catch the fairing halves, however, at the end of 2020 this program was canceled due to safety risks and a low success rate. On Starlink Group 4-13, SpaceX recovered the fairing halves from the water with their recovery vessel NRC Quest.
In 2021, SpaceX started flying a new version of the Falcon 9 fairing. The new “upgraded” version has vents only at the top of each fairing half, by the gap between the halves, whereas the old version had vents placed spread equidistantly around the base of the fairing. Moving the vents decreases the chance of water getting into the fairing, making the chance of a successful scoop significantly higher.
All times are approximate
|00:38:00||SpaceX Launch Director verifies go for propellant load|
|00:35:00||RP-1 (rocket grade kerosene) loading underway|
|00:35:00||1st stage LOX (liquid oxygen) loading underway|
|00:16:00||2nd stage LOX loading underway|
|00:07:00||Falcon 9 begins engine chill prior to launch|
|00:01:00||Command flight computer to begin final prelaunch checks|
|00:01:00||Propellant tank pressurization to flight pressure begins|
|00:00:45||SpaceX Launch Director verifies go for launch|
|00:00:03||Engine controller commands engine ignition sequence to start|
|00:00:00||Falcon 9 liftoff|
Starlink Group 4-13 Launch, Landing, and Deployment
All times are approximate
|00:01:12||Max Q (moment of peak mechanical stress on the rocket)|
|00:02:30||1st stage main engine cutoff (MECO)|
|00:02:34||1st and 2nd stages separate|
|00:02:40||2nd stage engine starts (SES-1)|
|00:06:25||1st stage entry burn start|
|00:06:44||1st stage entry burn complete|
|00:08:10||1st stage landing burn start|
|00:08:33||1st stage landing|
|00:08:46||2nd stage engine cutoff (SECO-1)|
|00:53:40||2nd stage engine starts (SES-2)|
|00:53:41||2nd stage engine cutoff (SECO-2)|
|01:02:42||Starlink satellites deploy|
Supermassive black hole at the center of our galaxy revealed – Earth.com
By use of extremely powerful telescopes, scientists had previously seen stars orbiting around something invisible, compact, and very massive at the center of our galaxy. This object – known as Sagittarius A* (Sgr A*) – appears to be a huge black hole located 27,000 light-years away from Earth. Now, for the fist time, astrophysicists have managed to capture an image of this supermassive black hole – which is four million times more massive than our sun – at the heart of the Milky Way.
Although the black hole itself is invisible, glowing gas around it reveals a tell-tale signature: a dark central region – called a “shadow”- surrounded by a bright ring-like structure, which is the light bent by the enormous gravity of the black hole.
“For decades, astronomers have wondered what lies at the heart of our galaxy, pulling stars into tight orbits through its immense gravity,” said Michael Johnson, an astrophysicist at Harvard University. “With the image [captured by Event Horizon Telescope or EHT], we have zoomed in a thousand times closer than these orbits, where the gravity grows a million times stronger. At this close range, the black hole accelerates matter to close to the speed of light and bends the paths of photons in the warped (space-time).”
“We were stunned by how well the size of the ring agreed with predictions from Einstein’s theory of general relativity,” added EHT Project Scientist Geoffrey Bower. “These unprecedented observations have greatly improved our understanding of what happens at the very center of our galaxy and offer new insights on how these giant black holes interact with their surroundings.”
To image the black hole, scientists used the powerful EHT, which linked together eight radio observatories across the planet to form a single, “Earth-sized” virtual telescope. By employing this groundbreaking technology to observe Sgr A* on multiple nights and collect data for long periods of time, the researchers created a library of millions of images which then needed to be interpreted theoretically to assess what type of astronomical objects they had in fact detected.
“To understand how the EHT has produced an image of Sgr A* one can think of producing a picture of a mountain peak based on a time-lapse video,” explained Luciano Rezzolla, a theoretical astrophysicist at Goethe University Frankfurt. “While most of the time the peak will be visible in the time-lapse video, there are times when it is not because it is obscured by clouds. On average, however, the peak is clearly there. Something similar is true also for Sgr A*, whose observations lead to thousands of images which have been collected in four classes and then averaged according to their properties. The end result is a clear first image of the black hole at the center of the Milky Way.”
This breakthrough discovery follows EHT’s 2019 release of the first image of a black hole, called M87*, located at the center of the more distant Messier 87 galaxy. Even though our galaxy’s black hole is over a thousand times smaller than M87*, the two astronomical objects look amazingly similar. Now, the scientists can compare the two to shed more light on how gas behaves around supermassive black holes.
“Now we can study the differences between these two supermassive black holes to gain valuable new clues about how this important process works,” said EHT scientist Keiichi Asada. “We have images for two black holes — one at the large end and one at the small end of supermassive black holes in the Universe — so we can go a lot further in testing how gravity behaves in these extreme environments than ever before.”
A detailed description of Sgr A* is published in the Astrophysical Journal Letters.
Image Credit: Younsi, Fromm, Mizuno & Rezzolla (University College London, Goethe University Frankfurt
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