Faculty

Richard Parnas on FOG, Biofuels, and Wastewater Management

Professor Emeritus of Chemical and Biomolecular Engineering, Richard Parnas, has been working on solutions to the oily waste we humans produce on a daily basis.  He has been on a journey to convert that waste into usable energy.  This quest has led to the patent of proprietary technology and the formation of REA Resources Recovery Services, a company he co-founded.  Along with his partners in the company and in partnership with UConn, Dr. Parnas set about to convert FOG (Fat, Oil, Grease) into biodiesel for the benefit of municipalities in the state.

In 2019, REA contracted with the City of Danbury to build a FOG to biodiesel processing facility at the city’s wastewater treatment plant.  That project has entered the construction phase and Parnas, REA, and UConn are now looking forward to the day the facility converts its first oily waste into usable biodiesel.  IMS News reached out to Dr. Parnas about his research, the Danbury project, and the future of wastewater management.

Richard Parnas
Dr. Richard Parnas

You have been researching and developing methods to convert FOG (Fat, Oil, Grease) into biodiesel fuel since 2006.  When did you first become interested in biofuels and what about biodiesel, in particular, led you down your current path?

I’ve been interested in biofuels, and green processing and green materials in general, for many years before coming to UConn. One of the important motivations for joining UConn was to participate in the development of the green economy. An undergraduate helped get me started working on biodiesel in the summer of 2007 by simply requesting my help to set up a biodiesel synthesis reaction in a fume hood.

When you became Director of the Biofuel Consortium here at UConn, you moved the bar from six gallons of biofuel produced over the course of a year to over 50 gallons continual production daily less than three years later.  When did you realize the scale at which you might be able to convert FOG into biodiesel?  What were the obstacles you faced and how were they overcome?

We used the yellow grease from UConn cafeterias to make biodiesel at that time, and the scale of operations was determined by the yellow grease production rate from the cafeterias. As a Chemical Engineer, my goal is always to maximize the use of available raw materials, and waste as small a fraction of that raw material as possible. Shortly after we started the Biofuel Consortium, we polled the various food service establishments at UConn to determine the yellow grease availability, and found it to be over 100 gallons per week. We then designed, built and installed a 50 gallon batch system, and produced 2 or 3 of the 50 gallon batches each week.

There were a number of obstacles. Production at that scale is not a typical academic activity so we faced skepticism from the facilities folks that ran the fuel depot for the buses. They asked if our fuel would be any good and how we would prove it to them, so we had to set up testing capability. Our testing was developed and run by Prof. James Stuart, an analytical chemist. Prof. Stuart and I received a grant of over $600,000 dollars to set up a biodiesel fuel quality testing facility in the Center for Environmental Science and Engineering (CESE) to test our biodiesel and the biodiesel produced by private companies. We also faced skepticism from the UConn administration since we were operating at a much larger scale than is typical. Safety concerns are important when conducting such operations with students who are just learning how to handle chemicals.

REA Resource Recovery Systems, a company which you co-founded and worked in collaboration with UConn to patent exclusive technology, has entered Phase 4 of itsREA Logo planned development of a 5000 square foot facility in Danbury that will turn FOG into biofuel.  How important is wastewater management for municipalities and what will be the benefits for the City of Danbury once the facility is online.

I joined my two partners, Al Barbarotta and Eric Metz, to found REA at the end of 2017. The UConn patents were already in place for a piece of core technology called a counterflow multi-phase reactor that plays a key role in both the chemical conversion and in the product purification. Prof. Nicholas Leadbeatter from Chemistry is a co-inventor with me on that reactor, along with two undergraduate students. Beginning in 2015, I started working with a very low grade feedstock called brown grease, which is much harder to process than the yellow grease we had been working with earlier. Every single wastewater treatment plant in the world has a brown grease management and disposal problem, and every municipality has a wastewater management problem. In much of the world, wastewater management is required by law and heavily regulated to ensure that effluent meets standards for discharge into rivers and oceans.

Here in CT, the brown grease problem was handled by DEEP many years ago by mandating that certain wastewater treatment plants in the state become FOG receiving stations. Brown grease is the component of FOG that causes all the problems. These FOG receiving stations were given a small set of choices as to how to dispose of the brown grease they received, such as by landfilling or incineration. All the choices cost money and vectored pollution into the air, the land, or the water.

Danbury was mandated to become a FOG receiving facility several years ago, and undertook a general plant upgrade project to build a FOG receiving facility and then dispose of the FOG using biodigesters. When that disposal pathway became too difficult due to high cost they sought alternatives. REA was ready at that time to provide the alternative of converting the brown grease into a salable product, biodiesel. This solution provides two benefits to Danbury, an environmentally excellent disposal method and a source of revenue. REA estimates that the revenue will offset the cost of the project in Danbury in about 7 years, and that the payback period will be significantly shorter in larger facilities.

It has been 15 years since you undertook this journey of making biodiesel a viable alternative energy source.  How does it feel to see your years of work coming to fruition with the Danbury project?

It feels terrifying because we have not yet started up the Danbury plant. When we successfully start Danbury, the relief and satisfaction will be enormous. Until then, for the next few months, everyone associated with the project is working very hard to finish the installation.

Since retiring in 2020, you appear to be just as active in your pursuit of science.  What continues to drive you and is there anything you miss now that you have retired?

I am driven by the desire to see this biodiesel project through to completion and by the desire to play some small role in mitigating the unfolding climate catastrophe. When I started at UConn I was surprised that the academic definition of project completion is a final report. As an engineer, that did not seem to be enough because most reports are ignored and forgotten. Sometimes I miss the teaching aspect of working at UConn, but I think I most miss the camaraderie of my colleagues, with whom I have much less time now than I used to.

Department of Energy Early Career Award Recipient Yuanyuan Zhu

Yuanyuan Zhu
Dr. Yuanyuan Zhu is the only Connecticut recipient of the DOE Early Career Award for 2022.

Established in 2010, the DOE Office of Science Early Career Research Program supports the individual research programs of outstanding scientists early in their careers and stimulates research careers in the disciplines supported by the DOE Office of Science: Advanced Scientific Computing Research (ASCR), Biological and Environmental Research (BER), Basic Energy Sciences (BES), Fusion Energy Sciences (FES), High Energy Physics (HEP), Isotope R&D and Production (IP), and Nuclear Physics (NP).

Among the 83 university and DOE national lab researchers announced as recipients of the award for 2022, Assistant Professor of Materials Science and Engineering Yuanyuan Zhu is the only Connecticut researcher to receive the honor.  IMS News asked Dr. Zhu about her research and the award.

In 2019, you were appointed Director of the UConn DENSsolutions InToEM Center for in-situ TEM research at IPB Tech Park.  You have since had papers published related to the research the Center is conducting.  As we are seeing more and more evidence of the effects of climate change, how do you hope your research at the InToEM Center will assist in solving some of the problems we are now dealing with?

Yes, we have published a couple of papers since 2019 using the in-situ environmental TEM gas cell. Here you can find our full publications: https://scholar.google.com/citations?hl=en&user=HlDqamcAAAAJ&view_op=list_works&sortby=pubdate .

It’s a coincidence that the DENSsolutions’ ETEM gas cell system is named as “Climate”, because it involves gas environment for chemical reactions in a microscope. Another example is their liquid cell system, which is called “Stream” simply because the reaction stimuli involved.

There are many materials researches related to energy and environment, including climate change, that can benefit from the in-situ ETEM research. One immediate example is heterogeneous catalysis used for natural gas conversion and H2 production. And the fusion energy materials research funded by the DOE ECA is another good example.

Congratulations on receiving the Department of Energy’s Early Career Award for 2022.  What are your hopes for your research on Understanding Thermal Oxidation of Tungsten and the Impact to Radiation Under Fusion Extremes?

Fusion energy holds great promise for replacing fossil fuels for 24/7 baseload electrical power. We are excited that the DOE Early Career Award will fund our in-situ ETEM study to directly address a well-known fusion safety hazard concerning aggressive high-temperature oxidation of plasma-facing material tungsten. We hope to gain fundamental understanding of tungsten degradation in case of air-ingress scenarios that could inform the best strategy for responding to accidents, and could guide the design of advanced W-based materials that better preserve divertor integrity for even more demanding DEMO fusion extremes. Simply put it, we want to make the operation of fusion energy systems safer and more reliable.

You have several Ph.D. candidates under your advisement.  How do you hope to influence these young scientists?

Our research group provides a welcoming, supportive and inclusive working environment to drive personal success for each Ph.D. researcher. Through the first-hand work on such research projects closely to clean energy and sustainability, I believe our Ph.D. students will gain confidence and skills in research and also develop a solid sense of social responsibility.

We are seeing many more women represented in STEM.  What advice would you give to young women who may be considering a career in science, technology, engineering and mathematics?

We need everyone in STEM, and anything is possible if one follows his/her/their passion. Research is fun but progress is built on failure and resilience.

 

Cato Laurencin Honored by American Orthopaedic Association

from UConn Today

Dr. Cato Laurencin
Dr. Cato T. Laurencin is now added to the AOA Award Hall of Fame (AOA Photo/Kyle Klein).

Dr. Cato T. Laurencin, University Professor at the University of Connecticut, has been honored by the American Orthopaedic Association (AOA) with its Distinguished Contributions to Orthopaedics Award adding him to its AOA Award Hall of Fame.

Laurencin, the Albert and Wilda Van Dusen Distinguished Professor of Orthopaedic Surgery at UConn School of Medicine, was selected for the special recognition by his AOA member peers for his remarkable personal achievement and contributions to orthopaedic surgery.

He accepted the award the evening of June 15 at the AOA’s Annual Leadership Meeting at the Rhode Island Convention Center in Providence. “I am so honored to accept the American Orthopaedic Association Distinguished Contributions to Orthopaedics Award and be recognized in the AOA Awards Hall of Fame. I feel so fortunate to be an orthopaedic surgeon.”

The AOA Distinguished Contributions to Orthopaedics (DCO) Award recognizes Laurencin for his personal achievement and broad contribution to the orthopaedic specialty, leadership, impact on patient care, and clinical and basic science research. The mission of the AOA is engaging the orthopaedic community to develop leaders, strategies and resources to guide the future of musculoskeletal care.

In addition to being a practicing sports medicine and shoulder surgeon consistently named to America’s Top Doctors list, Laurencin is a world-renowned surgeon-engineer-scientist and a pioneer of the field of regenerative engineering.

In fact, Laurencin is leading the first international effort ever for knee and limb engineering with his Hartford Engineering a Limb (HEAL) project which aims at regenerating a human limb by 2030. The National Institutes of Health and the National Science Foundation currently fund this research work through Laurencin’s large grant awards including the NIH Director’s Pioneer Grant Award and the National Science Foundation’s Emerging Frontiers in Research and Innovation Grant Award.

In orthopaedic surgery, Laurencin has been the first to win the “trifecta” of orthopaedic research lifetime awards: the Nicolas Andry Award from the Association of Bone and Joint Surgeons, the Marshall R. Urist Award from the Orthopaedic Research Society, and the Kappa Delta Award from the American Academy of Orthopaedic Surgeons.

Nationally, Laurencin is the first surgeon in history to be elected to all four national academies: the National Academy of Sciences, the National Academy of Engineering, the National Academy of Medicine, and the National Academy of Inventors. He is an elected fellow of the American Academy of Arts and Sciences and an elected fellow of the American Association for the Advancement of Science.

Laurencin is a laureate of the National Medal of Technology and Innovation, America’s highest honor for technological achievement, awarded by President Barack Obama at the White House. He is the recipient of the prestigious Spingarn Medal, the highest honor of the NAACP bestowed upon such Americans as Martin Luther King Jr., Maya Angelou, George Washington Carver, Jackie Robinson, and Duke Ellington.

At UConn Laurencin is also a professor of chemical engineering, materials science and engineering, and biomedical engineering and serves as CEO of The Connecticut Convergence Institute for Translation in Regenerative Engineering. He has received the highest honors in engineering, medicine and science, including the Philip Hauge Abelson Prize given for “signal contributions to the advancement of science in the United States.”  The American Institute of Chemical Engineers recently established the Cato T. Laurencin Regenerative Engineering Founder’s Award in honor of his breakthrough achievements in that field.

Laurencin received his BSE in chemical engineering from Princeton University, his MD, magna cum laude from the Harvard Medical School, and his Ph.D. in biochemical engineering/biotechnology from the Massachusetts Institute of Technology.

Anna Tarakanova is Studying Elastins to Develop Aging-Related Therapies

from UConn Today

Dr. Anna Tarakanova
Mechanical engineering professor Anna Tarakanova listens during the 2020 Women in STEM Frontiers in Research Expo, which she co-organized. (Contributed photo)

Anna Tarakanova has long had an interest in how objects and bodies work. Her chosen specialty in the field of Mechanical Engineering – studying the structure, function, and mechanics of biological systems and materials, especially fibrous protein materials such as elastin and collagen – merges the two.

The assistant professor of mechanical engineering and her team are working to establish a high-fidelity modeling framework for both healthy and degenerated elastins for use as a tool to resolve different pathological stressors affecting how elastin functions from a nanoscale.

During aging and with chronic, often age-related illnesses such as diabetes, cardiovascular disease, and osteoarthritis, elastin can degenerate, causing a decline in normal function. Elastin is an essential structural protein that gives the skin, heart, blood vessels, and other elastic tissues in the body the stretchy quality they need to function.

“At the molecular scale, there are a number of physical-chemical modifications that occur that drive this mechanical degeneration over time,” Tarakanova says. “Because they are quite numerous and act in parallel, it’s difficult to deconstruct which triggers impact mechanics and to what degree. If we can understand the mechanism, we can think about novel therapies to target aging and aging-associated diseases.”

Tarakanova’s work has earned her a 2022 Early Career Development (CAREER) Award from the National Science Foundation. She is one of 11 junior faculty members at UConn this year to receive the coveted award, which recognizes the recipient’s potential as a role model in education and research.

CAREER Awards come with five years of funding intended to provide a foundation for a young professor’s research program. Beyond advancing her research, Tarakanova plans to use the funding to create activities and events to engage and support undergraduate and graduate students, especially those from underrepresented groups. The effort will include a reboot of a Women In STEM Frontiers in Research Expo she co-organized with a colleague in January 2020.

“For me, it was kind of a natural extension of what I wanted to do as a professor, being a woman in STEM and being a minority for most of my education career,” Tarakanova says.

Elastin and collagen are not the only protein materials getting her attention. Early in the pandemic, Tarakanova and two of her graduate students began exploring the spike protein associated with SARS-CoV-2 to figure out how it moved when it interacted with the immune system. She is now working with Paulo Verardi, a pathobiologist in UConn’s College of Agriculture, Health and Natural Resources, and UConn biochemist Simon White to develop new and potentially better ways to stabilize spike proteins for use in COVID-19 vaccines, particularly in relation to emerging new variants of the virus.

“Some of the methods we are using to study the spike protein are related to the methods that we’ve used and continue to use to look at elastin,” she says. “It’s a different project, but it does broadly fall under this fusing of computing and computational models, physics, biomechanics, and biochemistry to understand the dynamic behavior of the COVID spike protein, the protein that sits on part of the corona.”

Rapid Virus Test Being Studied in Zhang Group will Differentiate SARS-CoV-2 from Other Respiratory Viruses

Yi Zhang Group
(from left to right) Guangfu Wu, Huijie Li, and Zhengyan Weng, advised by Professor Yi Zhang, are checking an array of graphene field-effect transistors.

In recent years, from H1N1 and now to SARS-CoV-2, global pandemics caused by highly contagious viral species have been threatening human life and putting tremendous pressure on healthcare services as well as the economy. Rapid testing and timely interventions for asymptomatic or mild infections caused by SARS-CoV-2, for example, would enable efficient quarantine of infected patients, thus significantly reducing the spread rate of the virus. Importantly, SARS-CoV-2 is expected to continue in the future fall/winter seasons, when it will coincide with the seasonal outbreak of other infectious respiratory diseases, including those caused by influenza virus and respiratory syncytial virus, which have similar signs and symptoms in the early stages. Considering the overlap in the seasonal peaks, symptoms, and underlying risk factors of these illnesses, having a rapid test to detect and differentiate SARS-CoV-2 from other infectious respiratory viruses will be clinically important.

In response to this clinical need, the Institute of Materials Science and Biomedical Engineering Assistant Professor Yi Zhang led the development of the most sensitive amplification-free SARS-CoV-2 diagnostic platform, the CRISPR Cas13a graphene field-effect transistor. This study, entitled “Amplification-Free Detection of SARS-CoV-2 and Respiratory Syncytial Virus Using CRISPR Cas13a and Graphene Field-Effect Transistors,” was published online on May 12, 2022, in the journal Angewandte Chemie International Edition.

“The key features of viral diagnostics are rapidness and sensitivity,” said Zhang. According to Zhang, most virus detection techniques, including the gold-standard RT-PCR, relies on viral sequence amplification, which can dramatically complicate the detection process and increase the risk of cross-contamination, therefore subject to elevated false-positive rates. However, current amplification-free methods are still limited by compromised sensitivity. “Our work revolutionized the field of amplification-free nucleic acid diagnostics by introducing a biosensing platform with sensitivity comparable with RT-PCR,” he said.

Yi Zhang
Dr. Yi Zhang

Derived from adaptive immunity in prokaryotes, Nobel-winning clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated (Cas) technology leverages nucleic acid base pair complementarity between a guide RNA and targeted nucleic acid sequence and affords high target specificity capable of discriminating single mismatches. Recently, several CRISPR/Cas systems, including Cas13a, were found to perform cleavage of nonspecific bystander nucleic acid probes triggered by target detection, known as “collateral cleavage.” Such collateral cleavage demonstrates a multi-turnover behavior, turning a single target recognition event into multiple probe cleavage events, and therefore leads to signal amplification.

“The idea of our biosensor design originates from exploiting the signal amplification by translating CRISPR technology onto an ultrasensitive detection platform,” said Huijie Li, a Ph.D. student in Zhang’s lab; she is also the leading first author of the study. Graphene, as a two-dimensional material, exhibits extraordinary charge carrier mobility and thus high electrical conductivity. Thanks to its atomic thickness, graphene, when constructed into biosensors as a sensing material, is highly sensitive to the interaction with biological analytes. In this study, by immobilizing probes on graphene-based field-effect transistors and allowing Cas13a collateral cleavage of these probes activated by target detection, SARS-CoV-2 down to 1 aM level in both spiked and clinical samples, was successfully detected within a 30 min detection time.

Simply by changing the guide RNA design, CRISPR Cas13a graphene field-effect transistor platform was reconfigured to target respiratory syncytial virus with the same attomolar sensitivity. “As the COVID-19 pandemic wanes, our virus diagnostic tool can be easily adapted to combat the future outbreak of unknown viral species,” Guangfu Wu, a Postdoc in Zhang’s lab; he is the co-first author of this work, said.

This study marks a significant milestone towards our goal of developing an integrated point-of-care biosensing platform for viral diagnostics. “We are aiming to offer patients a fast, ultrasensitive all-in-one tool that can streamline sample treatment and analysis and deliver results without any specialized training,” said Zhengyan Weng, a Ph.D. student in Zhang’s lab; he is also the co-first author of this study.

 

This research is supported by the University of Connecticut start-up and the National Science Foundation under the award number CBET-2103025. The collaborators of this work include Dr. Xue Gao at Rice University (co-corresponding author), Drs. Kevin D. Dieckhaus and Lori Avery at UConn Health, and Dr. Yupeng Chen in the Department of Biomedical Engineering at UConn.

Seven IMS Faculty Members Promoted

Faculty Promotions 2022
(l-r) Drs. Yupeng Chen, Elena Dormidontova, Ali Gokirmak, Ying Li, Xiuling Lu, Thanh Nguyen, Arash Zaghi

The Office of the Provost recently announced the award of promotion and/or tenure to 69 faculty across the Storrs and regional campuses. Seven IMS faculty members were among them.

Evaluations for promotion, tenure, and reappointment apply the highest standards of professional achievement in scholarship, teaching, and service for each faculty member evaluated. Applications for promotion and tenure are reviewed at the department level, school or college level, and finally at the Office of the Provost before recommendations are forwarded to the Board of Trustees.

Newly promoted IMS faculty members include:

From the School of Engineering

Promotion to Associate Professor and Tenure

  • Ying Li, Mechanical Engineering
  • Thanh Nguyen, Mechanical Engineering

Promotion to Professor

Tenure as Associate Professor

From the College of Liberal Arts and Sciences

Promotion to Professor

From the School of Pharmacy

Promotion to Professor

  • Xiuling Lu, Pharmaceutical Sciences

IMS congratulates each of these faculty members for their excellence and dedication.

Four IMS Faculty Members Receive OVPR Scholarship Facilitation Award

Scholarship Facilitation Award Winners
(l-r) Drs. Farhad Imani, Jasna Jankovic, Tomoyasu Mani, and Luyi Sun

The Scholarship Facilitation Fund program provides up to $2,000 to UConn faculty across all disciplines. The OVPR offers the competitive awards to promote, support, and enhance research, scholarship, and creative endeavors across UConn Storrs and regional campuses.

Four IMS faculty members were among the 67 faculty named as recipient of the award for Spring 2022:

  • Farhad Imani, Mechanical Engineering
    Brain-inspired Hyperdimensional Computing for Empowering Cognitive Additive Manufacturing
  • Jasna Jankovic, Material Science and Engineering
    STEAM Tree Earth Day Celebration
  • Tomoyasu Mani, Chemistry
    Stereoselective Control of Electron Transfer Reactions
  • Luyi Sun, Chemical and Biomolecular Engineering
    Publication in PNAS, a Premium Journal for Maximum Impact

IMS Congratulates these faculty members on this accomplishment.

Materials Research Society Features Nate Hohman in Podcast

MRS Bulletin PodcastNate Hohman is the feature of the Materials Research Society (MRS) podcast, MRS Bulletin. Laura Leay interviews Hohman about the structure of two chalcogenolates his group uncovered. By combining serial femtosecond crystallography —usually used to characterize large molecules—and a clique algorithm, Hohman’s group was able to analyze the structure of small molecules. With serial femtosecond crystallography, large molecules like proteins produce thousands of spots on the detector; in contrast, small molecule crystals only a produce a few spots. The algorithm uses the pattern that the spots make on the detector to determine the orientation of as many crystals in the liquid jet as possible. The data from each crystal can then be merged together to find the structure. Nate’s research is featured in the 2022 IMS Annual Newsletter.

Yang Cao in Collaboration on Project Funded by ARPA-E OPEN 2021

Yang Cao
Dr. Yang Cao

On February 14, 2022, ARPA-E announced $175 million for 68 OPEN 2021 research and development projects aimed at developing disruptive technologies to strengthen the nation’s advanced energy enterprise. These high-impact, high-risk technologies support novel approaches to clean energy challenges.

Associate Professor and Electrical Insulation Resource Center (EIRC) Director Yang Cao and fellow researchers from Virginia Polytechnic Institute and State University (Virginia Tech) will combine the functionality benefits of power electronics with the power density benefits of high-voltage cables to create a cohesive, all-in-one structure to replace bulky, inflexible power substations in today’s electrical grid. This “substation within a cable” design uses a cascade of coaxial power conversion cells to gradually step-down voltage to levels required by the loads. Virginia Tech’s module can achieve high power density and a form factor that enables seamless integration with the cable by mimicking a coaxial geometry design. This could eliminate the need for large and expensive power substations and enable simple integration of renewable energy sources, an electric vehicle fast-charging infrastructure, energy storage, and efficient direct current distribution lines.

The research project, Substation in a Cable for Adaptable, Low-cost Electrical Distribution (SCALED) has received $2,953,389 in funding support through the ARPA-E OPEN 2021 initiative.

Four IMS Faculty Members Elected to CASE

Hebert-Kumbar-Nieh-Teschke
(l-r) Drs. Rainer Hebert, Sangamesh Kumbar, Mu-Ping Nieh, and Carolyn Teschke

The Connecticut Academy of Science and Engineering (CASE) announced the election of 35 new members for 2022 who the organization describe as leading experts in science, engineering, mathematics, medicine, and technology.  12 of those newly elected members are UConn faculty and four are faculty members of the Institute of Materials Science (IMS).

Rainer Hebert, Professor of Materials Science and Engineering; Director of Pratt & Whitney Additive Manufacturing Center, Associate Director of the Institute of Materials Science

Sangamesh G. Kumbar, Associate Professor, Orthopaedic Surgery, Biomedical Engineering Health

Mu-Ping Nieh, Professor, Dept. of Chemical and Biomolecular Engineering, UConn School of Engineering and Institute of Materials Science

Carolyn Teschke, Professor and Interim Department Head, Molecular and Cell Biology, and Chemistry

The new members will be introduced at the Academy’s 47th Annual Meeting to be held virtually on May 26, 2022.  Read the full UConn Today story