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7 Burning Questions For The MLB Stretch Run

Now that the MLB All-Star Game is over — with hometown favorite Shane Bieber winning MVP (despite not even being the most valuable pitcher on his own team) — the baseball world can finally turn its attention toward the stretch run of the season, in games that actually count. 2019 has given us some interesting twists already: For all the division races that have gone mostly according to expectations, there are several others that definitely haven’t, and the same goes for unexpected breakout players cropping up among the old standbys. So with a little help from our MLB Elo ratings and probabilities, let’s take a look at the important questions that will be answered in the second half:Can Cody Bellinger hold off Mike Trout?A healthy Mike Trout is usually a strong pick to lead the majors in WAR. From the Los Angeles Angels outfielder’s first full MLB season in 2012 through 2018, Trout finished first among hitters in WAR four times in seven chances. The only exceptions were 2015 (when Bryce Harper rattled off what looks like one of the all-time fluke seasons), 2017 (when Trout was injured for a big part of the season) and 2018 (when both happened — Trout was hurt and Mookie Betts also had an all-time great campaign). The 27-year-old Trout has already passed numerous Hall of Famers in career WAR, so it makes sense that it would take either an injury or a historic rival season to dethrone him from his customary spot atop the league leaderboard.This year, Trout is healthy, which is a big part of the equation. He’s also having one of his best-ever seasons at the plate. But this time, the rival performance is an all-time great one being served up by Dodgers right fielder Cody Bellinger, who is on pace for 10.8 WAR by season’s end (which would rank among the top 30 or so seasons by a batter in MLB history). Bellinger streaked ahead of Trout relatively early in the season and hasn’t looked back — though maybe he should start checking the rearview mirror. With a .476 weighted on-base average to Bellinger’s .303 over the past 14 days, Trout has now pulled within 0.07 WAR of his Dodger counterpart on the season. And on top of his stellar numbers, Trout is also one of the most consistent players in baseball history, so he’s likely to get to his usual (astronomical) WAR level by the end of the year. The real question is whether Bellinger can continue to keep pace with this crazy career year of his own.Can the Twins hang on to the AL Central?The Minnesota Twins have easily been the most surprising team of the season thus far, staking themselves to the majors’ third-best record (56-33) and a 5½-game lead over the Cleveland Indians in the AL Central. Before the season, our model thought Cleveland had the edge in talent over Minnesota, even if the Tribe had allowed their gap over the rest of the division to narrow since 2018. But that gap ended up being much smaller than anyone imagined — perhaps even nonexistent! In addition to its superior record, Minnesota has vastly outperformed Cleveland in terms of run differential (+116 to +27) and total wins above replacement1Averaging together the two versions found at Baseball-Reference.com and FanGraphs. (31.3 to 19.6).Even so, our Elo ratings think the Indians are gaining on the Twins recently, especially after Cleveland trimmed Minnesota’s division lead from 11 games on June 15 to half that in a little over three weeks. Our model still gives Minnesota a 78 percent chance of resisting a Cleveland surge, and some of the Tribe’s problems aren’t going away soon. Injured ace Corey Kluber hasn’t pitched in months, and fellow starter Carlos Carrasco recently announced that he had been diagnosed with leukemia. But it’s also fair to wonder whether third baseman Jose Ramirez — an MVP candidate in 2018 — will continue to be one of baseball’s most disappointing players in the second half, as well as if some of the most unexpectedly good Twins (Jorge Polanco, Mitch Garver, Jake Odorizzi, etc.) will stay as hot going forward. If the teams play more to the form our model had originally predicted, this could be a very intriguing battle.Who will win the National League Central?At the All-Star break, the NL Central is baseball’s only division with a leader up by five games or fewer. (It’s only the second case since the six-division era started in 1994 where just one division was within five games at the break .) The FiveThirtyEight predictions make it even clearer how tight this division is: the Chicago Cubs lead with just a 42 percent probability of winning the Central — making them the only current division favorite with less than a 70 percent chance to win — and four teams have a double-digit probability, including Chicago, the Milwaukee Brewers (26 percent), St. Louis Cardinals (14 percent) and Pittsburgh Pirates (11 percent). (Even the cellar-dwelling Cincinnati Reds still have a 7 percent shot at the division title.)The Cubs would seem to have the edge in the second half, however. They have a +55 run differential, while two of their four division rivals have actually been outscored this season. (The Brewers have a -17 scoring margin, and the Pirates have one of -36; the closest competitor to Chicago is actually Cincinnati at +27, even though the Reds have the worst record of all four Cub rivals.) The Brewers have the best individual player of the division in right fielder Christian Yelich (on pace for 8.8 WAR), and they sent five players to the All-Star Game, tied for the second-most of any MLB team. But they’ve also seen their share of letdowns, headlined by Lorenzo Cain and Travis Shaw. Whichever NL Central teams lose out on the playoffs, one thing’s for sure: they will be disappointed, given how close they were with two and a half months left in the regular season.How wrong was I about Washington?About a month ago, I wrote that the NL East race — which once looked like a four-team battle between the Washington Nationals, New York Mets, Atlanta Braves and Philadelphia Phillies — had been winnowed down to just the Braves and Phillies. Well, one of those teams has kept winning: Atlanta is 11-6 since June 18. But Philadelphia promptly went 8-11 over that same span, while Washington has gone 14-4 and increased its Elo rating by 8.4 points, sixth-most in baseball behind the Pirates, Giants, Athletics, Yankees and Orioles.As a result, the NL East race has shifted — if slightly.It still looks like a two-team race, and the Braves are still at the top. In fact, Atlanta’s odds of winning the division have only gotten even better over the past month, rising from 59 percent to 72 percent. But the Nationals now have the second-best chance of winning the East, at 19 percent, with the Phillies dropping down to 9 percent. Washington is also now likely to make the playoffs (58 percent), while Philly has just a 38 percent chance of getting into the postseason. The teams are separated by just a half-game in the standings, but there’s no question Bryce Harper’s old team has played better than his new one in the first half of 2019.2Washington has the superior run differential and WAR tally, in addition to a 16-point edge in Elo. The degree to which Washington can threaten the Braves depends on how much they keep proving me wrong.How top-heavy can baseball get?Our model currently predicts that four teams — the Yankees, Dodgers, Astros and Twins — will finish with at least 98 wins (with three of those cracking triple-digits). If that happens, it would be the most 98-win teams in a single season since 2002, when five teams broke that barrier. At the same time, five teams are projected for 98 or more losses (including four tracking for triple-digit defeats). If that holds up, it would tie last season for the most such teams since 1977.This kind of thing is nothing new in the modern world of MLB, where the tanking trend has led to a bunch of bottom-feeders waving the white flag while a bunch of powerhouses destroy them. But even by those recent standards, the 2019 season could break new ground in top-heaviness. It might make for some less-than-compelling regular season contests down the stretch, particularly once rosters expand in September — but it could also lead to multiple titanic postseason matchups between teams with gaudy records, particularly in the AL.Will the home runs ever let up?If the 2019 season is remembered for anything, it seems likely that it will go down as the Year of the Home Run. (Until the next Year of the Home Run, that is.) So far this season, 1.37 balls have left the yard on average every game, which would shatter the all-time record (set in 2017) by nearly 9 percent if it holds up in the second half. 25 of 30 teams have hit at least 100 homers before the All-Star break, while 35 different players hit at least 20 bombs, and nine have hit at least 25. Overall, the 3,691 home runs smashed so far are, according to ESPN’s Stats & Information Group, the most in a first half in baseball history. (The previous record was 3,343 in 2017.)With August, traditionally one of the most homer-heavy months, still remaining to be played, it seems likely that the all-time record for most dingers in a single MLB season will be obliterated. Love or hate the homer-centric style of baseball being played in today’s game — let’s ask Justin Verlander what he thinks — the long ball is more fundamental to the fabric of the sport than it’s ever been, and it shows no signs of slowing down anytime soon.Will the champs even make the playoffs?The Boston Red Sox have turned things around some since their abysmal start to the season, winning 18 of their past 30 games (a 97-win pace per 162 games). Although staff ace Chris Sale continues to struggle (5.96 ERA in the last month), the 2019 Sox have at least mostly begun to resemble the fearsome team that dominated MLB essentially from wire to wire a season ago. But is it too little, too late?According to the FiveThirtyEight model, Boston has less than a coin flip’s chance (47 percent) to make the playoffs heading into the season’s home stretch. That number includes almost no chance of winning the AL East (6 percent), both because the rival New York Yankees have played so well and because the Tampa Bay Rays have exceeded expectations (again) and are on pace to win 92 games according to our model. That leaves the Red Sox in a numbers game for the AL’s other Wild Card slot, which is looking like it will go to the Indians — who themselves have been squeezed by the upstart Twins. In other words, some quality AL team will be left out of the postseason, and right now that team is looking like the defending champs, thanks to their early season World Series hangover.Check out our latest MLB predictions. read more

Bahamas Davis secures near 80 of PLP vote

first_imgFacebook Twitter Google+LinkedInPinterestWhatsApp Related Items:#PhillipDavisnewPLPleader Davis officially sworn in as Opposition Leader Facebook Twitter Google+LinkedInPinterestWhatsAppNassau, Bahamas – October 27, 2017 – Nearly 80% of the delegates’ votes went to Philip Brave Davis to make him officially now the leader of the Opposition, Progressive Liberal Party.It was evident that the country’s oldest living political party was not yet ready to make the history making move of having the first female party leader in Glenys Hanna Martin who lost soundly in the race, which ended two days before her birthday which is today.The MP for Englerston got 300 votes while Davis, the MP for Cat Island, Rum Cay and San Salvador took the title with a whopping 1,004.Grand Bahama resident, Troy Garvey had three votes in support of his bid with 12 spoiled ballots, according to media reports. Recommended for youlast_img read more

Selfdriving trucks go postal in USPS twoweek pilot

first_img 4 More From Roadshow Autonomous Vehicles Trucks Self-driving trucks have the chance to transform the logistics industry, and even the federal government is working to determine how well the tech can work in its nascent stages.The United States Postal Service will begin a two-week pilot program that will put self-driving trucks to work delivering mail. The USPS will use trucks from TuSimple, a startup working to bring the first commercial self-driving semi to market. The pilot program will consist of five round trips ferrying USPS trailers between Phoenix and Dallas, each leg covering more than 1,000 miles. The trucks will be driven along the I-10, I-20 and I-30 interstates, and the drives will take place at all hours of the day and night. Like many other AV pilot programs, there will be a safety engineer and driver on board to monitor the truck and, if necessary, take command.Enlarge ImageIt’s unclear if the trucks will carry USPS branding, or if the cabs will sport the same TuSimple getup seen here. TuSimple TuSimple said that this kind of trip is exactly what self-driving trucks are made for. Each 22-hour leg, with a short turnaround time, would usually require two drivers working in tandem and sharing some awfully close confines. Using AVs would eliminate the need to bathe in another person’s musk for nearly a full day at a time, which seems like a benefit. Of course, the USPS sees benefits beyond smell. “This pilot is just one of many ways the Postal Service is innovating and investing in its future,” said a USPS spokesperson in an emailed statement. “We are conducting research and testing as part of our efforts to operate a future class of vehicles which will incorporate new technology to accommodate a diverse mail mix, enhance safety, improve service, reduce emissions, and produce operational savings.”Driver shortages are hitting the logistics industry in a big way. American Trucking Association statistics estimate that the industry could be short some 175,000 drivers by 2024, so it’s a good time for self-driving trucks to start making moves. tusimple-inlineEnlarge ImageHaving driven most of this route in the past, I can assure you that it’s just about as lonely (and pretty) as it looks. TuSimple Tags Share your voicecenter_img 2020 Hyundai Palisade review: Posh enough to make Genesis jealous Comments 2020 Kia Telluride review: Kia’s new SUV has big style and bigger value 2020 BMW M340i review: A dash of M makes everything betterlast_img read more

Pakistan Airlines trolled for saying sausage and baked beans are taste of

first_imgRepresentational picture: Pakistan International Airlines flightFAROOQ NAEEM/AFP/Getty ImagesPakistan International Airlines incurred the wrath of many following an advertisement stating that a breakfast of sausages and baked beans was the taste of home. In the ad, which was trending on Twitter, the airlines said it will serve the ‘taste of home’ on board and they will do that with a dash of salt and pepper. Pakistan International Airlines wrote: “Just when you start missing it, we serve you a taste of home! A dash of salt and little bit of pepper, we tantalize your taste buds with our delicious meal to welcome the glorious morning! #PIA #BreakfastWithPIA” TwitterThis triggered a series of replies to the tweet with angry Twitterati saying that Anda and paratha was a taste of home and not an English breakfast with sausages and baked beans with an omelette.One angry Twitter user replied: “Please ask the Air Marshal running the airline if this is for Pakistanis or Brits. I ask because this is not a taste of home for Pakistanis and for Brits hash browns and bacon are missing.”Another user placated the situation saying that he would prefer this breakfast compared to the “greasy omelettes and the dry bun.”last_img read more

ASK demands probe into BCL attack on quota reformists

first_img.Ain O Salish Kendra (ASK), a rights body, has urged the government to investigate the attacks on the quota reformists by Bangladesh Chhatra League (BCL) activists and to release Rashed Khan, joint convener of Bangladesh General Students Rights Protection Council immediately.It made the demand in a statement issued on Sunday.The statement signed by ASK executive director Sheepa Hafiza said, “On Saturday morning, at least 10 leaders of the central committee of the council were injured in an attack by some BCL men on the DU campus. Police arrested Rashed in a case filed by a BCL leader which is very regrettable.”It also criticised the silence of the Dhaka University (DU) administration over the attack and its failure to control it.Terming the BCL attack on students ‘unacceptable’, the rights body asked the government to identify the attackers immediately and mete out exemplary punishment to them.last_img read more

Modi plans jobs quota for upper caste poor

first_imgIndian Prime Minister Narendra Modi waves to the crowd as he arrives in Medininagar on 5 January 2019, during a campaign sweep through Jharkhand state to inaugurate development projects. Photo: AFPIndia prime minister Narendra Modi’s government announced plans Monday to set aside a quota of government jobs for poorer members of India’s upper caste, months before what looks set to be a challenging re-election bid.India already “reserves” jobs for impoverished and disadvantaged lower castes for civil service jobs and college places, but this has caused resentment among other communities, who say it is unfair and freezes them out.Modi’s plans would help households with an annual income of less than $11,000, the Press Trust of India news agency reported. The change would require a change to the constitution, which caps the number of reserved jobs and college places at 50 per cent.The plans were approved by Modi’s cabinet on Monday. They require approval from both houses of parliament.Modi’s Hindu nationalist Bharatiya Janata Party (BJP) swept to power in 2014, but late last year it suffered painful defeats in three key state elections to the opposition Congress party led by Rahul Gandhi, scion of the Nehru-Gandhi dynasty.Abhishek Singhvi, a Congress spokesman, said on Twitter that the latest move was an “election gimmick” and “proof positive” of Modi’s “fear” of losing power in the vote, which is due to take place by May.Caste-based quotas are meant to provide equal opportunities for India’s poorest and most marginalised groups. Nearly one in four Indians still lives on less than $1.25 a day.Demands for quotas for highly sought-after government jobs and university places have escalated in recent years as unemployment has risen and conditions in rural areas have worsened.In 2016 at least 10 people were killed when thousands of Patidars, a relatively well-off caste of farmers and traders, took to the streets in the western state of Gujarat to demand they be included in those quotas.Similar protests by upper caste groups have been witnessed in other states including Maharashtra and Haryana.last_img read more

Brexiteers plot EU vote mischief

first_imgFrench president Emmanuel Macron (R) accompanies out british prime minister Theresa May after a meeting at the Elysee Palace in Paris on 9 April. Photo: AFPThey call it the Trojan Horse strategy: Brexit supporters furious at their government’s failure to leave the EU on time are aiming to undermine the European Parliament following elections next month.The Greek myth about the hollow wooden horse Odysseus used to sneak his men into Troy to capture it from within was invoked by Conservative MP Mark Francois ahead of Wednesday’s critical EU summit.”If we were to be held in the EU against our democratically expressed will because some in the EU hope against hope that we will change our mind, then they will live to regret it,” Francois told a Brexiteer conference in the heart of London.”We will become a Trojan Horse within the EU and utterly derail all their attempts to pursue a more federalist project,” he said from a lectern bearing a portrait of Margaret Thatcher — a premier whose views on Europe grew darker with time.Francois warned EU leaders meeting in Brussels later Wednesday to consider the UK government’s request for another Brexit delay that “they will need to bear all these inconvenient truths in mind”.As difficult as possibleThese inconvenient truths were first raised in a tweet last Friday by Jacob Rees-Mogg — the leader of a rightwing insurgency tearing at prime minister Theresa May’s Conservative Party.”If a long extension leaves us stuck in the EU we should be as difficult as possible,” Rees-Mogg wrote moments after May asked Brussels to push back Britain’s departure to keep it from crashing out.EU leaders’ expected approval will put Britain in the paradoxical situation of having to take part in European Parliament elections on 23 May — nearly three years after voting to chart its own course.Rees-Mogg said Britain should make best use of its predicament by vetoing “any increase in the (EU) budget, obstruct the putative EU army and block (French President Emmanuel) Macron’s integrationist schemes”.Francois pointed cheerfully to a response to Rees-Mogg’s tweet from the European Parliament’s Brexit coordinator Guy Verhofstadt that also went viral.”For those in the EU who may be tempted to further extend the Brexit saga, I can only say, be careful what you wish for,” Verhofstadt wrote.”Who am I to put try and put it better than Guy Verhofstadt,” Francois chortled.FireworksRees-Mogg and Francois voted against the Brexit deal that May struck with the EU all three times it came up for a vote. They view it as too EU-friendly.Only 26 of the 314 Conservatives in parliament joined them the last time around — a shrinking group that May hopes will grow even smaller by the time she tries to get her pact through on the fourth attempt.Her ability to do this quickly could still keep Britain from having to actually fill its 73 seats when a new European Parliament opens its doors in July.Some of the current places have in any case been reassigned.Yet the level of Conservatives’ anger with May seems to be rising as the possibility grows of Brexit being pushed further out of reach.Ninety-seven Conservative MPs voted against a measure Tuesday aimed at averting a no-deal scenario. It prevailed by a 420-110 margin.Veteran EU foes such as Nigel Farage — a poster boy of the pro-Brexit campaign who once headed the nationalist UKIP group — hope the groundswell of discontent will carry his new Brexit Party to big gains in Europe.”If we have to fight those European election on 23 May, we’ll fight them because it’s time we taught them a lesson,” Farage says in a video campaign message.And even those not running themselves sound tempted by the idea of Britain making a nuisance of itself in European halls of power.Asked whether he might consider running in the European elections, veteran Conservative MP William Cash told parliament this week: “I must admit that if I were to, there would be quite a lot of fireworks in the European Parliament”.last_img read more

Baltimore Man Named in Killing of Taylor Hayes

first_imgBy J. K. Schmid, Special to the AFROPolice announced the arrest of a Baltimore man, suspected in the murder of 7-year-old Taylor Hayes at a 2 p.m. press conference today.“I’d like to announce the arrest of of 29-year-old Keon Gray of Baltimore for the murder of 7-year-old Taylor Hayes,” said Interim Baltimore City Police Commissioner Gary Tuggle, flanked by Hayes’s family and Chief Deputy State’s Attorney Michael Schatzow. “Of course, Mr. Gray is innocent until proven guilty, but this is a long time coming with respect to the arrest of the person that we are alleging is responsible, or one of the persons we are alleging is responsible for Taylor’s death.”Keon Gray (pictured) is alleged by Chief Deputy State’s Attorney, Michael Schatzow (left) and Interim Baltimore City Police Commissioner Gary Tuggle (center) to be Taylor Hayes’s killer at a press conference with the Hayes family (right). (Courtesy Photo)Baltimore Police have named Daneka McDonald, whom they allege to be Gray’s girlfriend, as an accessory after the fact.Hayes was shot in the back at approximately 2:30 p.m. July 5 while seated in the back of a car in Southwest Baltimore. Officer Steven Reed, first on the scene, “did everything he could to save her life,” Tuggle said. Hayes was put under the care of Dr. Thomas Scalea and what Tuggle described as an “incredible team,” with University of Maryland Shock Trauma.Hayes died July 19.The coda of the 10-minute conference was community coming together.“The community rallied around the family. When you see the number of tips, and there was great investigative work, by not just Baltimore City Police Department, but by surrounding jurisdictions,” Tuggle said. “An incredible effort between this department, the state’s attorney’s office, and just really solid police work on the part of homicide, warrant apprehension task force, the district police officers, and a number of folks that sort of took this personally.”Tuggle thanked Anne Arundel County, the jurisdiction where Gray was apprehended, for its support.At the time of the conference, Gray was in custody, but had not yet been delivered to the jurisdiction of Baltimore.“We took this case very seriously, as we do all homicide cases,” Schatzow said. “Today’s arrest was the result of very diligent and effective teamwork between Baltimore Police Department and the City’s State’s Attorney’s office. I’d like to recognize Assistant State’s Attorneys Charles Blomquist, and Matthew Pillion, who led our efforts and worked very closely over a long period of time, in order to get to this day.”Schatzow concluded by echoing Tuggle’s advisement, that Gray is innocent until proven guilty in a court of law.“It takes a little relief from Shanika, but at the end of the day, she’s still don’t have her daughter back,” said Ebony Ward, Hayes’s aunt, on behalf of the Hayes family.Ward expressed much more certainty than city officials, thanking them for arresting Hayes’s killer.“It’s about to be a long road, but we’re gonna get through it,” Ward said. “It won’t bring Taylor back, but at least we’re about to get some type of justice. And we just want to thank everybody for all their hard work, and we really appreciate it.”In the wake of the brutal beating of an unarmed man by a Baltimore police officer, a reporter asked Tuggle if the city needed a result like this.“Hundreds of things in this city happen that are positive every single day,” Tuggle said. “Unfortunately, it gets overshadowed by the one or two negative things. The community came together to support Taylor’s family, to support the police department, and for a time, we put everything to the side, we put all of our differences to the side, to come together to make this thing happen… If we’re gonna move forward, those are the kinds of things it takes to move forward. I’m particularly proud of where we are today, and really sad that we had to get here this way.”last_img read more

Continuous breathing metalorganic framework with guest selectivity

first_img More information: Elliot J. Carrington et al. Solvent-switchable continuous-breathing behaviour in a diamondoid metal–organic framework and its influence on CO2 versus CH4 selectivity, Nature Chemistry (2017). DOI: 10.1038/nchem.2747AbstractUnderstanding the behaviour of flexible metal–organic frameworks (MOFs)—porous crystalline materials that undergo a structural change upon exposure to an external stimulus—underpins their design as responsive materials for specific applications, such as gas separation, molecular sensing, catalysis and drug delivery. Reversible transformations of a MOF between open- and closed-pore forms—a behaviour known as ‘breathing’—typically occur through well-defined crystallographic transitions. By contrast, continuous breathing is rare, and detailed characterization has remained very limited. Here we report a continuous-breathing mechanism that was studied by single-crystal diffraction in a MOF with a diamondoid network, (Me2NH2)[In(ABDC)2] (ABDC, 2-aminobenzene-1,4-dicarboxylate). Desolvation of the MOF in two different solvents leads to two polymorphic activated forms with very different pore openings, markedly different gas-adsorption capacities and different CO2 versus CH4 selectivities. Partial desolvation introduces a gating pressure associated with CO2 adsorption, which shows that the framework can also undergo a combination of stepped and continuous breathing. Proposed role of guest–framework interactions in the solvent-dependent continuous-breathing properties of SHF-61. Credit: (c) Nature Chemistry (2017). DOI: 10.1038/nchem.2747 After heating SHF-61-CHCl3 to remove solvent, it exhibited type I adsorption isotherm behavior for N2 and CO2. This was as expected from previous studies. What was new for this study, though, was that CH4 also followed type I adsorption isotherm, but it took much longer for adsorption to occur. This kinetic difference allows for selective adsorption, which has implications for practical uses such as catalysis and separation techniques.Typically studies with MOFs are either all or nothing in the sense that the adsorption measurements are taken after complete desolvation of the MOF to determine total guest uptake. SHF-61 was also studied for gas adsorption as a partially desolvated MOF, which is the first of this kind of study. The partially desolvated SHF-61-DMF showed a stair-step isotherm instead of type I adsorption isotherm typical of an approximately fixed pore size. The mechanism at work here was identified by in situ powder x-ray diffraction and has to do with a sudden opening of the pores at a particular CO2 pressure threshold.Finally, while cation-framework interactions are difficult to study, crystallographic studies show that guest-framework and cation-framework interactions control the breathing mechanism, particularly whether the guest is able to overcome cation-framework interactions. This explains the stair-step adsorption pattern for the partially desolvated MOF. While adsorption of CO2 is at first slow, once the pressure of CO2 is high enough to overcome cation-framework interactions, then the pores open allowing for more CO2 to adsorb.This research demonstrates a unique continuous breathing MOF whose properties have allowed for unprecedented studies in the SHF-61’s mechanism and guest selectivity. This research has implications for molecular sensing for gas separation. Because the authors were able to gain new insights into continuous breathing MOFs, future research may include developing other continuous breathing MOFs. Journal information: Nature Chemistry Flexible metal-organic frameworks with range of pore sizes made by threading through molecular ligands 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. © 2017 Phys.org Explore further (Phys.org)—Researchers from the University of Sheffield report a new continuous-breathing metal-organic framework (MOF), SHF-61, that has two different solvent-specific forms, a narrow-pore structure that is the result of DMF or H2O desolvation and a wide-pore structure that is the result of CHCl3 desolvation. The wide-pore form showed uptake of N2, CO2, and CH4 with selectivity for CO2. They were also able to conduct single-crystal structure analysis of their MOF during breathing motions. Their work appears in Nature Chemistry. “Being modular in construction allows MOFs to be tailored for a wide variety of applications that exploit their molecular-scale porosity. Highly flexible MOFs remain uncommon, but offer the possibility of developing guest-responsive materials. Identifying new flexible MOFs may open many doors for applications, particularly in selective entrapment and release, separation and sensing of molecules,” explains Lee Brammer, who is Professor of Inorganic and Solid State Chemistry at the University of Sheffield. “The flexible behavior of SHF-61 is quite complicated, but what helped in this case is that it proved feasible to study the structural changes in some detail by single-crystal X-ray diffraction.”Breathing MOFs, are metal-organic frameworks whose structure reversibly changes upon some kind of external stimulus. Very few MOFs have been reported to display breathing behavior and of the known MOFs, most undergo some kind of structural change due to a crystal phase transition. This structural change leads to a difference in pore size, which, in turn, allows for the reversible adsorption and desorption of guests. Because these MOFs undergo a phase change, their adsorption profiles (i.e., adsorption isotherms) look like stair steps.What is not common among breathing MOFs is continuous rather than a stair-step adsorption profile. Continuous breathing MOFs, such as MIL-88, have proven difficult to isolate and study. This paper reports single-crystal and powder XRD studies of continuous-breathing MOF SHF-61.SHF-61, or (Me2NH2)[In(ABDC)2], where ABDC is 2-aminobenzene-1,4-dicarboxylate, has an In(III) metal coordinated to carboxylates that serve as hinges for the continuous breathing mechanism. The authors point out that the hinge is from rotation of the ABDC ligands around the O—-O of the carboxylates. This is accompanied by changes in the coordination geometry around In(III). The combination of the two motions enables the continuous breathing.Specifically, In(III) is chelated to four ABDC ligands providing a flattened tetrahedral geometry around the metal center. The resulting anionic framework has diamond-shaped pores, which contain dimethylammonium cations that balance the charge. The pore size is largely dependent on the solvent. Carrington et al. isolated solvated forms of the MOF, SHF-61-DMF and SHF-61-CHCl3, and demonstrated how removal of each solvent affects pore size, and therefore guest uptake, differently. Removal of the more strongly interacting DMF leads to narrowing of the pores whereas removal of the more weakly interacting CHCl3 leaves the pores fully open. Citation: Continuous breathing metal-organic framework with guest selectivity (2017, March 29) retrieved 18 August 2019 from https://phys.org/news/2017-03-metal-organic-framework-guest.htmllast_img read more