first_img This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. According to Guerin, a scientist at the Institute d’Optique Graduate School in Palaiseau (south of Paris), in order for an atom laser to be practicable for many applications, a method for creating longer wavelengths needs to be found. And, with his colleagues from Aspect’s Atom Optics Group of the Laboratoire Charles Fabry, he has. An article published in Physical Review Letters by Guerin and his coworkers Riou and Gaebler from the team led by Josse and Bouyer, is titled “Guided Quasicontinuous Atom Laser”; it demonstrates how this longer wavelength can be achieved.“By making our atom laser into a wave carrier, we can get rid of the acceleration of gravity,” says Guerin. “We can create an atom laser with a constant.” The French team’s Letter describes how such a laser works with trapped Bose-Einstein condensate (BEC):“The BEC, in a state sensitive to both trapping potentials, is submitted to a rf outcoupler yielding atoms in a state sensitive only to the optical potential, resulting in an atom laser propagating along the weak confining axis of the optical trap.”“By using quasicontinuous outcoupling,” Guerin further explains, “we can get a beam with much less interaction.” A guided quasicontinuous atom laser, such the one described, would allow for better atomic motion control during propagation. Better atomic control would pave the way for more coherent atom sources for use in atom interferometry. Additionally, this set-up for a guided atom laser has the potential to provide a variety of other useful future applications. Quantum transport is another field that could benefit from the work performed by the team led by Josse and Bouyer. The members of the team, though, are especially interested in the interferometry aspects illuminated by this new type of atom laser: “We could use this scheme not only to guide atom laser beams, but also to separate and then recombine them to get an interferometer, which can be used to measure rotations or accelerations.” Guerin also points out that such interferometer could also be realized on atom chips.Designs that can produce atom-wave interferometry can yield progress in sensor technology. One of these technologies, says Guerin, includes “Creating a gyroscope with coherent atomic beams.” The applications and information that could come from the work by the team in France are varied and many. But rather than getting too carried away with the future, Guerin sticks with the basics. “There are two main points that we have realized because of this work,” he says. “First, we have a well-defined and large wavelength. This is new.” He continues his explanation: “And, second, we can control the amounts of interaction. It is great that we can control the flux of the atom laser, by controlling the flux, we control the density inside the beam.” And it is great for the world of atomic science as well.By Miranda Marquit, Copyright 2006 PhysOrg.com Explore further Is random lasing possible with a cold atom cloud?center_img One of the biggest differences between photons and atoms is that the latter are massive particles, making gravity is a huge factor. It can be seen as an advantage when designing new high accuracy atom interferometers based inertial sensors, but can be a major drawback when controlling atom laser beams. “Gravity makes for higher velocity,” William Guerin explains to PhysOrg.com, “and that means wavelengths become small.” Citation: Guiding an Atom Laser (2006, November 24) retrieved 18 August 2019 from https://phys.org/news/2006-11-atom-laser.htmllast_img read more

first_imgAn idealized representation of the structure of NU-1000 based on single-crystal X-ray diffraction. Credit: (c) 2015 PNAS doi: 10.1073/pnas.1514485112 Mechanically interlocked molecules have several features that make them ideal candidates for molecular switches. These interlocked molecules, known as rotaxanes or catenanes, typically involve two molecular components that have distinct orientations based on interactions between them. Scientists can control which orientation the interlocked molecules take using stimuli, such as electrochemical potential or light. Redox active interlocked molecules are compelling candidates for a molecular switch. However, in solution, these molecules are unpredictable, and when it comes to designing circuitry, controlling the molecular switch is vital. This is where MOFs can be helpful. MOFs are highly porous materials. Other molecules can be trapped within the pores, and these pores can be chemically tailored to select for certain molecules. A group of researchers from Northwestern University in collaboration with Intel Labs and King Abdulaziz University have successfully captured a redox-active rotaxane within the pores of a premade MOF via post-synthetic building block replacement. Their paper is published in the Proceedings of the National Academy of Sciences.”As chemists, we have become proficient at manipulating molecular switches and rudimentary molecular machines in solution during the past quarter of a century,” said co-author Dr. Fraser Stoddart, “What we would really like to be able to do now is mount these switches inside porous solids in a rapid and changeable manner. This task has turned out to be easier said than done!”Previous research with mechanically interlocked molecules that are stabilized in a metal-organic framework involved building the MOF around the interlocked molecules in such a way that the “struts” of the MOF were also part of the interlocked molecule. There were several drawbacks to this process, including the need to optimize conditions so that a crystal would form, and in some cases, the molecules did not move, a necessary property for molecular switching. © 2015 Phys.org Citation: Solid-state molecular switches using redox active molecules in a porous crystal (2015, August 24) retrieved 18 August 2019 from https://phys.org/news/2015-08-solid-state-molecular-redox-molecules-porous.html (Phys.org)—A group of researchers have provided a proof-of-concept procedure for making a solid-state molecular-sized switch. They combined a mechanically interlocked molecule with a pre-synthetized metal-organic framework (MOF). Explore further McGonigal, et al. wanted to design a mechanically interlocked molecule that would fit within the pores of a pre-made MOF, rather than incorporate the molecule into the architecture of a novel MOF. They accomplished this by capturing a redox-active rotaxane within the pores of a zirconium-based MOF (NU-1000) post-synthetically using solvent-assisted ligand incorporation (SALI). Their model system provides a proof-of-concept.The first step in their procedure was to design the system. NU-1000 has hydroxyl groups that are oriented toward the center of a hexagonal channel. McGonigal, et al. realized that these hydroxyl groups could be displaced by carboxyl groups present in a rotaxane using solvent-assisted ligand incorporation (SALI). In this way, the carboxyl groups act as attachment points for the rotaxane. Their rotaxane needed to serve as a model system and work with their SALI procedure. They used a viologen-based molecule with a “stopper” on one end to ensure it becomes mechanically interlocked. Viologens are linear molecules comprised of two aromatic rings (pyridinium). This viologen was substituted with benzoic acid on one end to coordinate to the zirconium, and a benzene ring substituted with two tert-butyl groups to act as “stoppers.” Under reducing conditions, the viologen will complex with a tetracationic macrocycle containing two viologens as a result of radical-radical pairing interactions. The resulting semirotaxane was verified using spectroscopic methods.The newly formed mechanically interlocked molecule was then coaxed into the functionalized MOF. The semirotaxane diffuses through the channel of the MOF and is captured by coordinating to the Zr clusters. The t-butyl bulky end served as a “stopper.” Characterization studies verified that the semirotaxane was successfully incorporated into a post-synthetic MOF. The system was more stable than the semirotaxane in solution. Further, their studies indicated that the proportion of semirotaxane-to-MOF was not as expected. Rather than four semirotaxanes to one zirconium cluster, they observed a 1:1 ratio. Modeling showed that fewer dumbbells per channel allowed for packing in the channel without distorting the MOF architecture. Finally, electrochemical studies were done to confirm the switching behavior of the semirotaxane. McGonigal, et al. used electrophoretic deposition to deposit microcrystals of NU-1000 on conductive fluorine-doped tin oxide transparent electrodes. They then used their SALI procedure to obtain a thin film of the semirotaxane-MOF compound. Electrochemical studies confirmed that a large portion of the semirotaxane maintains its redox activity.According to Dr. Stoddart it was the simplicity of this this method that his group found appealing, “We make the molecular switches in solution, where we are already very comfortable with the chemistry, and then just mix them with some porous crystals. The switches insert themselves into the porous interiors of the crystals by means of some strong chemical bonds and that’s it! Switchable molecules slotted into crystals full of apace at the drop of a hat!” More information: “Electrochemically addressable trisradical rotaxanes organized within a metal-organic framework” PNAS DOI: 10.1073/pnas.1514485112AbstractThe organization of trisradical rotaxanes within the channels of a Zr6-based metal–organic framework (NU-1000) has been achieved postsynthetically by solvent-assisted ligand incorporation. Robust ZrIV–carboxylate bonds are forged between the Zr clusters of NU-1000 and carboxylic acid groups of rotaxane precursors (semirotaxanes) as part of this building block replacement strategy. Ultraviolet–visible–near-infrared (UV-Vis-NIR), electron paramagnetic resonance (EPR), and 1H nuclear magnetic resonance (NMR) spectroscopies all confirm the capture of redox-active rotaxanes within the mesoscale hexagonal channels of NU-1000. Cyclic voltammetry measurements performed on electroactive thin films of the resulting material indicate that redox-active viologen subunits located on the rotaxane components can be accessed electrochemically in the solid state. In contradistinction to previous methods, this strategy for the incorporation of mechanically interlocked molecules within porous materials circumvents the need for de novo synthesis of a metal–organic framework, making it a particularly convenient approach for the design and creation of solid-state molecular switches and machines. The results presented here provide proof-of-concept for the application of postsynthetic transformations in the integration of dynamic molecular machines with robust porous frameworks. This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only. Journal information: Proceedings of the National Academy of Sciences Toward solid-state molecular circuitry: Molecular shuttle within a metal-organic frameworklast_img read more

first_img by NPR News Bobby Allyn 8.22.19 5:35pm A disgruntled cook who threatened to carry out a mass shooting and had assembled an extensive stockpile of high-powered firearms, ammunition and tactical gear has been arrested, authorities in Long Beach, Calif., said. Police arrested Rodolfo Montoya, 37, at his Huntington Beach residence Tuesday after he told a co-worker at the Long Beach Marriott that he was planning to “shoot up fellow employees and people coming into the hotel,” said Police Chief Robert Luna during a news conference. According to investigators, Montoya was aggravated over a dispute involving the hotel’s human resources department and was planning to seek retribution. Police say one of Montoya’s colleagues reported the threat to police, an act authorities credited with thwarting what could have been a massacre. “Montoya had clear plans, intent and the means to carry out an act of violence that may have resulted in a mass casualty situation,” Luna said. “Because this was reported, I firmly believe many lives were saved.”Luna said after the report from one of Montoya’s co-workers was received by police on Monday, the department launched an investigation that involved searching Montoya’s Huntington Beach home, revealing a vast array of weapons, such as assault-style riles, high-capacity ammunition magazines and hundreds of bullets. The foiled plot marks at least the seventh instance of a potential mass attack being averted since gunmen in El Paso, Texas, and Dayton, Ohio, carried out shootings that left a total of 31 people dead in one weekend. In Nevada, prosecutors arrested a man suspected of trying to make a bomb to target a synagogue and a bar catering to LGBTQ patrons. Federal authorities in Connecticut last week intercepted a man who “showed interest” in a mass shooting. The same day, federal authorities in Maryland announced the arrest of a man who had made violent threats against a Jewish congregation. A day later, police in Daytona Beach, Fla., charged a man with making threats to commit a mass shooting in a large crowd. Then an Ohio man was arrested following a threatened attack on a Jewish community center. This week, prosecutors announced charges against a man in Maryland who allegedly made violent threats against Hispanic people. After that, federal agents arrested a Florida truck driver in Indianapolis who was suspected of planning a shootout in a church in Memphis, Tenn. Back in California, it is not known how Montoya obtained such a wide array of weapons and ammunition. With limited exemptions, assault weapons and high-capacity magazines are illegal for anyone to possess in California. Montoya is being held in the Long Beach City Jail on charges of manufacturing and distributing assault weapons, possession of an assault weapon and making a criminal threat.Copyright 2019 NPR. To see more, visit NPR. Police Seize Rifles, High-Capacity Magazines From Man… last_img read more

first_imgI’m in college. I’m deeply in love with a junior. She’s in 1st year. I don’t know how to express my feelings to her.Rajeev, HyderabadJust be brave enough to approach her and express. The age old ritual of a romantic love letter might also do the trick. Whatever way you adopt, I suggest, don’t waste time! Just express. Nothing to lose my dear. Woo her, make her feel special, gift her an orchid, take her out to movies, restaurants and just Bol Daalo! Best of luck!! Also Read – ‘Playing Jojo was emotionally exhausting’I have recently discovered that my younger brother is homosexual. My parents are not aware. I’m very nervous.Name withheld, DelhiSee my friend, don’t get nervous! Its fine! I understand, that ‘discovering’ this wasn’t a happy feeling but don’tcreate any situation that will lead your brother to take any drastic step or make him awkward. If he’s really young, there could be a chance that this ‘phase’ will pass. But, if it doesn’t, please be mature enough and make him  comfortable as this is his ‘preference’ and this is not a crime! Live and let live. Also Read – Leslie doing new comedy special with NetflixI’m 14 years old. My parents have informed me that they are getting divorced. I have been asked to decide on which parent I choose to stay with.  I’m shattered. Help!Neha, NoidaI’m really sorry to hear that but Neha, they must be having their reasons. You have to handle yourself with utmost care. Concentrate on activities that make you feel good – sport, friends, books. Think both from your head and heart and decide. Living with one doesn’t mean that you will be completely detached from the other. You  can spend time with both parents. You can also opt for a residential school if you want. Cheer up girl, life is beautiful and I’m sure, you will be happy always. My husband can’t satisfy me sexually. I’ve got involved with his cousin who lives with us. I’m enjoying sex but feel scared. What should I do?Name withheld, HaryanaGood to hear that you are ‘enjoying’. But yes! This case of cousin living in the same house is definitely a reason to worry. I suggest, please be extra careful. Nobody should get to know. Temporary joy shouldn’t lead to permanent problems.Sex is important but not at the cost of your mental peace and long term happiness.Is masturbation bad for health? Please advise.Tinu, BarodaWell, you haven’t mentioned details hence I’m sharing a general view.Masturbation is a part of sexual practices. In fact, most doctors also recommend it, not only to improve sex life but to also promote general health. However, like most things in life, too much of a good thing can be bad. Excessive masturbation can lead to symptoms like stress, fatigue, and memory loss. Have a love or life query you cannot find an answer to? Send your questions to -roopshashotm@gmail.comlast_img read more

first_imgKolkata: Sodepur station in North 24-Parganas on Wednesday turned into a battlefield after an irate mob carried out a rampage, ransacking a portion of the railway station due to wrong announcement of a train.The incident led to the disruption of train services in Sealdah main section on Wednesday morning for more than two hours, resulting in the cancelling of 15 pairs of EMU local trains. Around 21 EMU locals and three Mail trains were detained en-route for 50 minutes each. Also Read – Heavy rain hits traffic, flightsMany of the commuters put up a block on the railway track. Some local people hurled stones at the booking office, during which some passengers received injuries. It has been learnt that a problem in the public addressing system had triggered the incident.There was an announcement at Sodepur station at around 9:53 am, saying that a local train will arrive on platform number 2. Within few minutes, a Down Gede local came on the track but it did not stop at the platform. Instead, the train passed through the track in a slow pace like a galloping train. Some of the passengers tried boarding the running train. They eventually failed as the train picked up speed. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedFollowing the incident, the passengers became infuriated and they started ransacking a portion of the platform, ticket counter and cabins of railway employees. Some also put up a block on the railway track. A huge contingent of police from Barrackpore commissionerate rushed to the spot along with the railway police. They had resorted to lathi charge to disperse the mob.At least 12 local trains were cancelled after the incident. Normal train services were resumed at around 11:58 am on Wednesday.Many local trains were stranded in various stations. Passengers blamed the railway authorities for the incident. Railway authorities said that an error in the interlocking system at Halisahar had led to the incident.A railway spokesperson also said that people were informed on the interlocking works at Halisahar and its possible impact on train movement through newspapers.last_img read more

first_imgThe concern and contemplation on multiple aspects related to Mother Nature get expressed by works of Artist Uma Bardhan. She weaves her protagonists, Hindu God and Goddess, women, birds and other natural elements into visual thoughts, into strokes of spirituality as one breathe in the colours, flow with the textures and soak in the spirit of mother nature. The works are on display at the show Silk Route  – a journey from Bengal to Delhi from March 1- 30 at Gurgaon. Also Read – ‘Playing Jojo was emotionally exhausting’Born in 1945 , Bardhan originally from Kolkata, currently based in Gurgaon specialises in figurative paintings, landscapes in water colour on silk, oil on canvas and water mixable oil on canvas.She is one of a very few artist who uses a rare medium – water colour on silk. A painstaking process where a special silk cloth is mounted on board before it can be used for painting.She started painting from her early 20s. Her mastery over this art form is evident considering she spends 5 to 6 hours a day with her paintings. Also Read – Leslie doing new comedy special with NetflixAmong experiences she treasures most was the coveted first prize in water colour from Govt of West Bengal among others she has received throughout her career. One look at Uma Bardhan’s realistic works at her studio in Gurgaon mostly done in soothing colours easily catches the attention of art lover. What is more fascinating about her is dedication to learn different mediums of art and making them unique by sharing a different story in each of them. At 69 there is no stopping for her. “God is the supreme creator of this universe and i as an artist take extreme pleasure in reflecting his creation in their actual form” says artist Uma Bardhan. A look through her works reveals only one thing i.e. versatility. From nature landscapes to figurative to divine and to abstract covering different mediums is truly a joy to watch. Bardhan, whose repertoire includes nature scapes, Indian mythology and city life, got drawn to spiritual art in the later part of her career.Her paintings are an expression of her inner self, an expression of joy and epitome of creative energy. Besides representing nature bathed in bounteous colours , there is also an expression at the lives of women at rural Bengal . Being spiritual at heart Hindu God & Goddess always remains as part of her theme.When: March 1 – 30Where: Beanstalk, Gurgaonlast_img read more

first_imgKolkata: A committee led by Additional Chief Secretary of the state Transport department, Alapan Bandyopadhyay, has been formed to prepare a report to regulate bus fare according to the price of fuel.This comes at the time when the state government has been forced to give its nod to increase the bus fare by Re 1 for every 4 km, as the diesel price has gone up at an alarming rate.Following a meeting headed by Chief Minister Mamata Banerjee, with bus owners and operators associations, the state Transport minister Suvendu Adhikari said: “It has been thought to develop a mechanism, based on which the bus fare will get regulated as per the rate of diesel.” Also Read – Heavy rain hits traffic, flightsHe further said that a team that will be led by Bandyopadhyay, will prepare a report in this connection. The report will be prepared within a month and has to be submitted for the Chief Minister’s approval.Once the mechanism is in place, the bus fare will go down if the diesel price decreases and it will go up if bus operators have to buy the same at a higher price. But the regulatory commission will not be followed.It may be mentioned that this is the first time when such a step has been taken in the state and it would immensely help commuters. Also Read – Speeding Jaguar crashes into Merc, 2 B’deshi bystanders killedAccording to experts, this is going to be a unique step that the state Transport department would take, thanks to which people would not have to pay more when fuel prices decrease. It may be mentioned that the price of diesel keeps fluctuating. But never has such an initiative been taken, in which people have to pay less if the cost of operating buses goes down.It may be recalled that the state Transport department has taken several steps in the past seven years, for the benefit of commuters. The Pathadisha app was introduced by the state Transport department to help commuters get real time location of buses. Initially, it was only possible to get location of private buses. Later, a large section of private buses was also incorporated into the app.last_img read more

first_imgDelhi’s ruling Aam Aadmi Party on Wednesday questioned the “hurry” in alloting former President APJ Abdul Kalam’s bungalow here to Union Culture Minister Mahesh Sharma and suggested it should be converted into a Knowledge Centre instead.The party also urged the Centre to “hand over” the belongings of Kalam to Delhi government in case it lacks the required resources and space to create a memorial for the late President.Delhi Tourism Minister Kapil Mishra said “limiting” Kalam’s work to his place of birth Rameswaram, Tamil Nadu, and “shifting all his documents, books and even the Veena to Rameswaram is insulting.” Also Read – Man arrested for making hoax call at IGI airport “His residence should not be vacated but should be converted into a Knowledge Centre in loving memory of the legend. So many govt. residences being allotted permanently in the names of various political leaders, why so hurry in vacating Kalam’s house?” Mishra said through a series of tweets.Kalam had stayed at the 10 Rajaji Marg residence here after his term as President ended in 2007.“If Central Govt. doesn’t have resources and space to build a memorial of Dr. Kalam, let them just hand over all his belongings to Delhi Govt. Delhi deserves a memorial of Dr. Kalam, he belongs to all of us. His memorial should be in Delhi as well as in Rameshwaram,” Mishra, AAP’s Karawal Nagar MLA, said.last_img read more

first_imgKolkata: Bengal Imams’ Association has urged all Muslims taking part in Muharram processions not to carry arms like lathis or swords as this is against the principle of Islam.A press release, issued by Mohammad Yahiya, chairman Bengal Imams’ Association on September 14, read that to preserve democracy against monarchy, favourite grandson Hossain of the Great Nabi Hazrat became a martyr at Karbala.Unable to forget the brutal incident, some Muslims carry out processions to express grief and play lathi and swords which is against the principle of Shia and Sunni sects. Also Read – Rain batters Kolkata, cripples normal lifeHazrat Mohammad was a preacher of peace. He never wanted this.The best way to express grief is to observe fast on the day of Muharram and pray to Allah for the good of all, the statement added.It further mentioned that no procession with members carrying arms is desired and allowing children to hold the same in the procession is against the Shariat and the Indian Penal Code.The Association has urged all Muslims not to allow any children to take part in the anti-Islam activity. They urged people not to get swayed by any instigation.”It is our responsibility to project Islam as a religion of peace,” the release added.It further stated that it is to remind people that by organising processions to carry arms, none can claim to become developed, as conceived by Rahamatulla–Al Amin.The period, leading to the Ashura, the day of martyrdom, the 10th of Muharram, is marked with councils of contemplation, remembrance and narration of the event.last_img read more

first_imgDarjeeling: An 11-year-old Bleze Shampang of Soom Tea Estate had watched the glamour and glitter of Durga Puja in Kolkata on television. Since then, it has been his dream to visit Kolkata to witness the fanfare.Not only Ma Durga is all set to make his dream come true, he along with nine other children from economically challenged background will be inaugurate a Puja pandal in Kolkata. They will also judge and declare awards for some renowned big-budget Pujas in the city of Joy next week. Also Read – Rain batters Kolkata, cripples normal lifeConcern for Human Welfare (CHW), an NGO from Kolkata, backed by the Ramakrishna Mission Nivedita Educational and Cultural Centre (RKMNECC), Darjeeling, has organised this unique event with the support of the Gorkhaland Territorial Administration (GTA).The event “Paharer Chokhe Shomotoler Pujo” involves 10 children chosen from the economically weaker section of Darjeeling. They will get a chance to watch Durga Puja of Kolkata, judge them and also inaugurate Peerless Nagar Durga Puja on October 14. Also Read – Speeding Jaguar crashes into Mercedes car in Kolkata, 2 pedestrians killed”I am very excited. It will be my maiden ride on a train and a visit to Kolkata,” stated 17-year-old Priti Ram of Singmari, Darjeeling.This is the maiden visit to Kolkata for the 10 students, aged between 9 to 17 years. For some, it is their maiden visit to Siliguri too along with a train ride.In Kolkata, the children will visit the Puja pandals of Ekdalia Park, Tridhara Sammilani, Bhawanipore Swadin Sangha, Chetla Agrani Club, Suruchi Sangha, Naktala Udayan Sangh, Sreebhumi Sporting Club along with a visit to Belgharia Ramakrishna Mission and Belur Math. They will judge the Pujas on different parameters and hand out awards. The children along with escorts left for Kolkata from Darjeeling on Thursday and will return on October 16.”CHW had requested us to select ten children for this programme. It was a difficult task to select ten from among 55, who are beneficiaries of Gadadhar Abhyudaya Prakalpa (GAP) of Ramakrishna Mission in Darjeeling. We chose the best performers who are from the economically deprived background” said Swami Parananda who is in charge of GAP.GAP is a programme in which regular education, moral education, cultural education and physical training are provided to needy children along with food round the year.This is the 4th year of the event. Last year, owing to the political turmoil that gripped the Hills, the event could not take place.”We want the children to have exposure of the cities. The programme also acts like a bridge between the Hills and the plains,” stated Swami Nityasatyananda, in charge of the Darjeeling Center.last_img read more