Publications by authors named "Benjamin Sherman"

60 Publications

Photocatalytic hydrogen evolution from biomass conversion.

Nano Converg 2021 Feb 26;8(1). Epub 2021 Feb 26.

Department of Chemistry, State University of New York College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY, 13210, USA.

Biomass has incredible potential as an alternative to fossil fuels for energy production that is sustainable for the future of humanity. Hydrogen evolution from photocatalytic biomass conversion not only produces valuable carbon-free energy in the form of molecular hydrogen but also provides an avenue of production for industrially relevant biomass products. This photocatalytic conversion can be realized with efficient, sustainable reaction materials (biomass) and inexhaustible sunlight as the only energy inputs. Reported herein is a general strategy and mechanism for photocatalytic hydrogen evolution from biomass and biomass-derived substrates (including ethanol, glycerol, formic acid, glucose, and polysaccharides). Recent advancements in the synthesis and fundamental physical/mechanistic studies of novel photocatalysts for hydrogen evolution from biomass conversion are summarized. Also summarized are recent advancements in hydrogen evolution efficiency regarding biomass and biomass-derived substrates. Special emphasis is given to methods that utilize unprocessed biomass as a substrate or synthetic photocatalyst material, as the development of such will incur greater benefits towards a sustainable route for the evolution of hydrogen and production of chemical feedstocks.
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http://dx.doi.org/10.1186/s40580-021-00256-9DOI Listing
February 2021

The effects of thoracoplasty on immediate post-operative recovery in adolescent idiopathic scoliosis.

Eur Spine J 2021 Jan 18. Epub 2021 Jan 18.

Children's Hospital of Orange County, Orange, USA.

Purpose: The purpose of this study was to evaluate differences in pain, opiate utilization and oxygen (O) consumption during the immediate post-operative course for patients undergoing posterior spinal fusion (PSF) for adolescent idiopathic scoliosis (AIS) with and without thoracoplasty.

Methods: Patients aged 10-21 years old that had undergone PSF for AIS were identified from 1/1/16-8/1/18. A cohort of patients that did not have a thoracoplasty group was used as a control group. A standardized pain protocol (rapid response pathway) was implemented on all patients. A retrospective chart review was performed. Pre-operative, operative and post-operative data and SRS scores were analyzed.

Results: Forty-six patients (38 girls, 8 boys) were included, 23 in each group. The average age was 15.2 years (range 12.0-19.3) and BMI was 20.9 (range 13.1-37.6). Differences in visual analog scores, post-operative oxygen and narcotic consumption were not statistically significant on any POD. Total opiate utilization was 146.06 morphine milligram equivalents (MME) in the control group and 149.41 MME in the thoracoplasty group (p = 0.78). One-year SRS self-image scores were higher in the thoracoplasty group (4.24 vs 3.96) (p = 0.007). There was no difference in length of hospitalization (3.6 vs 3.5 days), levels fused (12.9 vs 12.9) or blood loss (334.1 vs 413.5 mL). There was one pleural effusion and no instances of intercostal neuralgia or pneumothorax in the thoracoplasty group.

Conclusion: There is no increase in immediate post-operative pain, narcotic use or oxygen consumption when a thoracoplasty is performed with a PSF for AIS. Improved SRS self-image scores were seen after thoracoplasty.
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http://dx.doi.org/10.1007/s00586-020-06715-xDOI Listing
January 2021

A molecular tandem cell for efficient solar water splitting.

Proc Natl Acad Sci U S A 2020 06 1;117(24):13256-13260. Epub 2020 Jun 1.

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599;

Artificial photosynthesis provides a way to store solar energy in chemical bonds. Achieving water splitting without an applied external potential bias provides the key to artificial photosynthetic devices. We describe here a tandem photoelectrochemical cell design that combines a dye-sensitized photoelectrosynthesis cell (DSPEC) and an organic solar cell (OSC) in a photoanode for water oxidation. When combined with a Pt electrode for H evolution, the electrode becomes part of a combined electrochemical cell for water splitting, 2HO → O + 2H, by increasing the voltage of the photoanode sufficiently to drive bias-free reduction of H to H The combined electrode gave a 1.5% solar conversion efficiency for water splitting with no external applied bias, providing a mimic for the tandem cell configuration of PSII in natural photosynthesis. The electrode provided sustained water splitting in the molecular photoelectrode with sustained photocurrent densities of 1.24 mA/cm for 1 h under 1-sun illumination with no applied bias.
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http://dx.doi.org/10.1073/pnas.2001753117DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306789PMC
June 2020

Hydrogen Peroxide Disproportionation with Manganese Macrocyclic Complexes of Cyclen and Pyclen.

Inorg Chem Front 2020 Apr 3;7(7):1573-1582. Epub 2020 Mar 3.

Department of Chemistry and Biochemistry, Texas Christian University, 2950 W.Bowie, Fort Worth, TX 76129, United States.

The catalase family of enzymes, which include a variety with a binuclear manganese active site, mitigate the risk from reactive oxygen species by facilitating the disproportionation of hydrogen peroxide into molecular oxygen and water. In this work, hydrogen peroxide disproportionation using complexes formed between manganese and cyclen or pyclen were investigated due to the spectroscopic similarities with the native MnCAT enzyme. Potentiometric titrations were used to construct speciation diagrams that identify the manganese complex compositions at different pH values. Each complex behaves as a functional mimic of catalase enzymes. UV-visible spectroscopic investigations of the HO decomposition reaction yielded information about the structure of the initial catalyst and intermediates that include monomeric and dimeric species. The results indicate that rigidity imparted by the pyridine ring of pyclen is a key factor in increased TON and TOF values measured compared to cyclen.
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http://dx.doi.org/10.1039/c9qi01509dDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7250372PMC
April 2020

Outcomes following surgical management of inguinal-related groin pain in athletes: a case series.

J Hip Preserv Surg 2020 Jan 22;7(1):103-108. Epub 2020 Jan 22.

Rush University Medical Center, Midwest Orthopaedics, 1611 W. Harrison Ave. Suite 300, Chicago, IL 60612, USA.

To determine the outcomes of a limited surgical intervention, consisting of neurolysis, inguinal wall repair and/or adductor debridement of adhesions based on intraoperative findings. Retrospective case series. Outpatient orthopedic/general surgery clinic. Fifty-one athletes treated surgically for inguinal-related groin pain from 2009 to 2015. Limited surgical intervention, consisting of neurolysis, inguinal wall repair and/or adductor debridement based on intra-operative findings. Ability to return to sport at the same level, time to return to play. Fifty-one athletes were included in the study with an average follow-up of 4.42 years (range 2.02-7.01). The average age was 24.2 years (range 16-49) and consisted of 94.0% males and 6.0% females. Nerve entrapment was demonstrated in 96.2% of cases with involvement of the ilioinguinal in 92.5%, the iliohypogastric in 30.8% and the genitofemoral in 13.2%. Attenuation of the posterior inguinal wall was present and repaired in 79.3% of cases. Scar tissue was present around the adductor origin and required debridement in 56.7% of cases. Forty-nine (96.1%) athletes returned to sport at the same level of play at an average of 5.9 weeks. Two athletes required a revision surgery. High rates of return to sport were achieved after surgery for inguinal-related groin pain that addresses the varying pathology and associated nerve entrapment.
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http://dx.doi.org/10.1093/jhps/hnz068DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7195923PMC
January 2020

Suture Tape Augmentation Repair of the Medial Patellofemoral Ligament.

Arthrosc Tech 2019 Oct 19;8(10):e1159-e1162. Epub 2019 Sep 19.

Riverside University Health System, Moreno Valley, California, U.S.A.

Adolescents with osteochondral loose bodies after a first-time patellar dislocation are most commonly treated with surgical intervention. However, the ideal method of managing a concurrent medial patellofemoral ligament (MPFL) disruption is still unknown. Recent evidence suggests high failure rates are associated with primary MPFL repair. The purpose of this Technical Note is to describe an alternative surgical technique for managing acute first-time patellar dislocations by using high-strength suture augmentation of the MPFL.
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http://dx.doi.org/10.1016/j.eats.2019.06.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6948125PMC
October 2019

Relaxation of the Medial Collateral Ligament to Facilitate Pediatric Meniscal Surgery.

Arthrosc Tech 2019 Nov 25;8(11):e1345-e1351. Epub 2019 Oct 25.

Riverside University Health System, Orange, California.

Meniscal injuries are becoming increasingly common in the pediatric population. During arthroscopic evaluation, pediatric patients typically have pristine articular cartilage and tight medial joint spaces. Therefore, when an arthroscope enters the medial compartment, iatrogenic damage to the articular cartilage may occur. Additionally, proper visualization of the medial meniscus (posterior horn or meniscocapsular junction) can prove to be difficult, and potential pathology may be missed. Proposed methods of increasing medial compartment visualization include the use of a 70° arthroscope placed through the intercondylar notch (Gillquist maneuver), creation of a posteromedial portal, or relaxation of the deep medial collateral ligament (MCL). Similar techniques have been described for use in adults for partial meniscectomy, but not in the pediatric population. The purpose of this Technical Note is to describe the steps to successfully perform the relaxation technique for meniscal repairs in pediatric patients, using an extra-articular outside-in percutaneous method.
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http://dx.doi.org/10.1016/j.eats.2019.07.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6926301PMC
November 2019

Youth Kicker's Knee: Lateral Distal Femoral Hemiphyseal Arrest Secondary to Chronic Repetitive Microtrauma.

J Am Acad Orthop Surg Glob Res Rev 2019 Aug 6;3(8):e079. Epub 2019 Aug 6.

Riverside University Health System, Moreno Valley, CA (Dr. Dempewolf, Dr. Sherman, and Dr. Schlechter); Western University of Health Sciences, Pomona, CA (Mr. Kwan); and Children's Hospital of Orange County, Orange, CA (Dr. Schlechter).

Year-round competitive sports place the youth athlete at risk for injury from chronic repetitive stress. Stress injuries to the distal femoral physis in adolescents are rare. This report highlights three male youth soccer players who presented with a lateral distal femoral hemiphyseal arrest and a subsequent unilateral genu valgum deformity in their dominant "kicking leg" due to repetitive microtrauma, a phenomenon we refer to as youth kicker's knee. Mean age was 14.2 years, and all participated in year-round soccer and American football. Imaging demonstrated aberration of the distal lateral femoral physis. All patients were surgically treated. Our series illustrates a unique presentation of a chronic overuse injury in hyper sporting adolescents resulting in an ipsilateral genu valgum deformity. Understanding adolescent growth and developmental characteristics is paramount to appropriate care, prevention, and treatment of physeal injuries that may occur from repetitive overuse and avoid surgery in these young athletes when possible.
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http://dx.doi.org/10.5435/JAAOSGlobal-D-19-00079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6754221PMC
August 2019

A stable dye-sensitized photoelectrosynthesis cell mediated by a NiO overlayer for water oxidation.

Proc Natl Acad Sci U S A 2020 06 5;117(23):12564-12571. Epub 2019 Sep 5.

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599;

In the development of photoelectrochemical cells for water splitting or CO reduction, a major challenge is O evolution at photoelectrodes that, in behavior, mimic photosystem II. At an appropriate semiconductor electrode, a water oxidation catalyst must be integrated with a visible light absorber in a stable half-cell configuration. Here, we describe an electrode consisting of a light absorber, an intermediate electron donor layer, and a water oxidation catalyst for sustained light driven water oxidation catalysis. In assembling the electrode on nanoparticle SnO/TiO electrodes, a Ru(II) polypyridyl complex was used as the light absorber, NiO was deposited as an overlayer, and a Ru(II) 2,2'-bipyridine-6,6'-dicarboxylate complex as the water oxidation catalyst. In the final electrode, addition of the NiO overlayer enhanced performance toward water oxidation with the final electrode operating with a 1.1 mA/cm photocurrent density for 2 h without decomposition under one sun illumination in a pH 4.65 solution. We attribute the enhanced performance to the role of NiO as an electron transfer mediator between the light absorber and the catalyst.
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http://dx.doi.org/10.1073/pnas.1821687116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7293597PMC
June 2020

Anatomic Acromioclavicular Ligament Reconstruction Using Semitendinosus Autograft With Suture Augmentation: Surgical Technique.

Arthrosc Tech 2019 Jun 23;8(6):e605-e610. Epub 2019 May 23.

Riverside University Health System, Moreno Valley, California, U.S.A.

Acromioclavicular (AC) joint separations are common injuries and account for 3.2% of shoulder injuries. These injuries typically occur among adolescent and young adult athletes during contact sports, such as hockey, wrestling, and rugby. Low-grade AC joint separations (Rockwood grade I-II) are often successfully treated nonoperatively. High-grade AC joint separations (Rockwood grade IV-VI) have the potential to alter scapular kinematics, causing painful and restricted motion, and are often treated surgically. Over 150 surgical techniques have been described to treat AC joint separations. Techniques vary in the types of implants used (screws, pins), use of anatomic or nonanatomic reconstructions, number of drill holes used, use of arthroscopic or open procedures, use of distal clavicle resection, and types of augmentation (allografts, autografts, sutures). The procedure can be expensive, with the implants and grafts costing varied amounts and, at times, thousands of dollars. The purpose of this Technical Note is to describe an inexpensive method of open anatomic AC joint reconstruction using a single bone tunnel, suture tape, and a semitendinosus autograft.
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http://dx.doi.org/10.1016/j.eats.2019.02.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6624191PMC
June 2019

A donor-chromophore-catalyst assembly for solar CO reduction.

Chem Sci 2019 Apr 14;10(16):4436-4444. Epub 2019 Mar 14.

Department of Chemistry , University of North Carolina Chapel Hill , Chapel Hill , North Carolina 27599 , USA . Email:

We describe here the preparation and characterization of a photocathode assembly for CO reduction to CO in 0.1 M LiClO acetonitrile. The assembly was formed on 1.0 μm thick mesoporous films of NiO using a layer-by-layer procedure based on Zr(iv)-phosphonate bridging units. The structure of the Zr(iv) bridged assembly, abbreviated as NiO|-DA-RuCP-Re(i), where DA is the dianiline-based electron donor (,,','-((CH)POH)-4,4'-dianiline), RuCP is the light absorber [Ru((4,4'-(POHCH)-2,2'-bipyridine)(2,2'-bipyridine))], and Re(i) is the CO reduction catalyst, Re((4,4'-POHCH)-2,2'-bipyridine)(CO)Cl. Visible light excitation of the assembly in CO saturated solution resulted in CO reduction to CO. A steady-state photocurrent density of 65 μA cm was achieved under one sun illumination and an IPCE value of 1.9% was obtained with 450 nm illumination. The importance of the DA aniline donor in the assembly as an initial site for reduction of the RuCP excited state was demonstrated by an 8 times higher photocurrent generated with DA present in the surface film compared to a control without DA. Nanosecond transient absorption measurements showed that the expected reduced one-electron intermediate, RuCP, was formed on a sub-nanosecond time scale with back electron transfer to the electrode on the microsecond timescale which competes with forward electron transfer to the Re(i) catalyst at = 2.6 μs ( = 2.7 × 10 s).
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http://dx.doi.org/10.1039/c8sc03316aDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6482438PMC
April 2019

Molecular Photoelectrode for Water Oxidation Inspired by Photosystem II.

J Am Chem Soc 2019 05 3;141(19):7926-7933. Epub 2019 May 3.

Department of Chemistry , University of North Carolina at Chapel Hill , Chapel Hill , North Carolina 27599-3290 , United States.

In artificial photosynthesis, the sun drives water splitting into H and O or converts CO into a useful form of carbon. In most schemes, water oxidation is typically the limiting half-reaction. Here, we introduce a molecular approach to the design of a photoanode that incorporates an electron acceptor, a sensitizer, an electron donor, and a water oxidation catalyst in a single molecular assembly. The strategy mimics the key elements in Photosystem II by initiating light-driven water oxidation with integration of a light absorber, an electron acceptor, an electron donor, and a catalyst in a controlled molecular environment on the surface of a conducting oxide electrode. Visible excitation of the assembly results in the appearance of reductive equivalents at the electrode and oxidative equivalents at a catalyst that persist for seconds in aqueous solutions. Steady-state illumination of the assembly with 440 nm light with an applied bias results in photoelectrochemical water oxidation with a per-photon absorbed efficiency of 2.3%. The results are notable in demonstrating that light-driven water oxidation can be carried out at a conductive electrode in a structure with the functional elements of Photosystem II including charge separation and water oxidation.
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http://dx.doi.org/10.1021/jacs.9b02548DOI Listing
May 2019

The Pie-Crusting Technique for Capsular Management During Hip Arthroscopy.

Arthrosc Tech 2019 Jan 1;8(1):e93-e96. Epub 2019 Jan 1.

Cedars Sinai Kerlan Jobe Institute, Santa Monica, California, U.S.A.

Hip arthroscopy is commonly performed for the treatment of femoroacetabular impingement and labral pathology. When arthroscopy for femoroacetabular impingement is performed, a capsulotomy is often utilized to maximize access and allow for improved visualization. When an extended interportal or T capsulotomy is performed, the iliofemoral ligament is transected, which can lead to micro or gross instability. The purpose of this Technical Note is to describe an alternative approach to the standard T capsulotomy using a pie crusting technique, which provides improved visualization of the femoral head-neck junction during the femoroplasty without the need for an extended capsulotomy and can also serve to create venting holes that prevent hematoma formation within the capsule.
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http://dx.doi.org/10.1016/j.eats.2018.09.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6408742PMC
January 2019

The Role of Orthobiologics in the Management of Osteoarthritis and Focal Cartilage Defects.

Orthopedics 2019 Mar;42(2):66-73

Individuals with osteoarthritis have a diminished quality of life, and the condition is a major cause of disability. Newer biologic treatments have been developed that are believed to modify disease progression. These predominantly include hyaluronic acid, platelet-rich plasma, bone marrow aspirate concentrate, and adipose-derived mesenchymal stem cells. There is conflicting evidence regarding the use of orthobiologics for osteoarthritis and for focal chondral defects, although most studies indicate that injections of biologics are safe and without significant adverse effects. [Orthopedics. 2019; 42(2):66-73.].
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http://dx.doi.org/10.3928/01477447-20190225-02DOI Listing
March 2019

Light-driven water oxidation by a dye-sensitized photoanode with a chromophore/catalyst assembly on a mesoporous double-shell electrode.

J Chem Phys 2019 Jan;150(4):041727

Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.

A mesoporous atomic layer deposition (ALD) double-shell electrode, AlO (insulating core)//ALD ZnO|ALD TiO, on a fluorine-doped tin oxide (FTO) conducting substrate was explored for a photoanode assembly, FTO//AlO (insulating core)//ALD ZnO|ALD TiO|-chromophore-catalyst, for light-driven water oxidation. Photocurrent densities at photoanodes based on mesoporous ALD double-shell (ALD ZnO|ALD TiO|) and ALD single-shell (ALD ZnO|, ALD TiO|) electrodes were investigated for O evaluation by a generator-collector dual working electrode configuration. The high photocurrent densities obtained based on the mesoporous ALD ZnO|ALD TiO photoanode for O evolution arise from a significant barrier to back electron transfer (BET) by the optimized tunneling barrier in the structure with the built-in electric field at the ALD ZnO|ALD TiO interface. The charge recombination is thus largely decreased. In the films, BET following injection has been investigated through kinetic nanosecond transient absorption spectra, and the results of energy band analysis are used to derive insight into the internal electronic structure of the electrodes.
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http://dx.doi.org/10.1063/1.5048780DOI Listing
January 2019

Cryopreserved, Viable Osteochondral Allograft for the Treatment of a Full-Thickness Cartilage Defect of the Glenoid.

Arthrosc Tech 2018 Dec 12;7(12):e1269-e1273. Epub 2018 Nov 12.

Cedars-Sinai Kerlan-Jobe Institute, Santa Monica, California, U.S.A.

Glenoid chondral injuries constitute challenging injuries to treat because of the limited access and the limited options and evidence available for their resolution. The purpose of this Technical Note is to describe the procedure, pearls, and pitfalls of implantation of a cryopreserved osteochondral allograft (Cartiform) for the treatment of full-thickness cartilage defects of the shoulder. Cartiform is a cryopreserved osteochondral allograft composed of chondrocytes, chondrogenic growth factors, and extracellular matrix proteins that can be implanted through a single-stage procedure.
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http://dx.doi.org/10.1016/j.eats.2018.08.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6306272PMC
December 2018

Hip and Core Muscle Injuries in Soccer.

Am J Orthop (Belle Mead NJ) 2018 Oct;47(10)

Riverside University Health System, 26520 Cactus Ave, Moreno Valley, CA 92555, USA. Email:

Soccer is the most popular sport in the world and has the fourth highest number of sports injuries. Hip and groin injuries account for 14% of soccer injuries and can be difficult to recognize and treat as they often require a high level of suspicion and advanced imaging. Groin pain can be separated into 3 categories: (1) defined clinical entities for groin pain (adductor-related, iliopsoas-related, inguinal-related [sports hernias/athletic pubalgia], and pubic-related groin pain), (2) hip-related groin pain (hip morphologic abnormalities, labral tears, and chondral injuries), and (3) other causes of groin pain. Conservative approaches are typically the first line of treatment, but operative intervention has been reported to result in higher rates of return to sport in athletes with hip-related and inguinal-related groin pain injuries. In patients with concurrent hip-related and inguinal-related groin pain, the failure to recognize the relationship and treat both conditions may result in lower rates of return to sport. Preseason screening programs can identify high-risk athletes, who may benefit from a targeted prevention program. Further study on exercise therapy, early surgical intervention, and potential biologic intervention are needed to determine the most effective methods of preventing groin injuries in athletes.
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http://dx.doi.org/10.12788/ajo.2018.0094DOI Listing
October 2018

Epidemiological Findings of Soccer Injuries During the 2017 Gold Cup.

Orthop J Sports Med 2018 Aug 20;6(8):2325967118791754. Epub 2018 Aug 20.

Cedars-Sinai Kerlan-Jobe Institute, Santa Monica, California, USA.

Background: Surveillance programs are vital to analyze the cause and nature of lesions and ultimately establish protocols of action to lower injury rates.

Purpose: To evaluate the adherence of team doctors to an electronic surveillance system and determine the incidence and characteristics of injuries among soccer players participating in the 2017 Gold Cup.

Study Design: Descriptive epidemiological study.

Methods: All data were collected from the electronic medical reports submitted during each match of the 2017 Gold Cup. Twelve teams participated in the tournament (each with 23 players), for a total of 276 players. A 19-question online survey was filled out by the team physician after each injury. Each report contained the player's number, the exact time of injury (minute of play), the location and diagnosis of injury as indicated by a previously defined code, and its severity in terms of the number of days of absence from training and match play.

Results: The electronic reporting system had a response rate of 100.0%, with 97.2% of questions answered completely. The mean age of injured players was 27 years (range, 21-35 years) and was not statistically significantly different from the overall mean player age ( > .05). There were no significant differences in the frequency of injuries when analyzed by player position ( = .743). The overall rate of injuries was 1.04 per match, with the most common injuries being contusions (42.3%), sprains (7.7%), strains (7.7%), and fractures (7.7%). These injuries were more commonly the result of contact (75.0%) than noncontact (25.0%) mechanisms ( < .001). Injuries most commonly occurred between the 60th and 75th minute of play when comparing all 15-minute time intervals ( = .004).

Conclusion: This study supports the use of electronic injury reporting, which demonstrated a high level of adherence among an international cohort of team physicians and has significant potential for improving injury surveillance and tracking responses to prevention programs. Injury rates in the Gold Cup were similar to those in previous studies and demonstrated the highest rates late in the second half of the game, specifically between the 60th and 75th minute of play.
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http://dx.doi.org/10.1177/2325967118791754DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6102768PMC
August 2018

Stabilized photoanodes for water oxidation by integration of organic dyes, water oxidation catalysts, and electron-transfer mediators.

Proc Natl Acad Sci U S A 2018 08 6;115(34):8523-8528. Epub 2018 Aug 6.

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599;

Stabilized photoanodes for light-driven water oxidation have been prepared on nanoparticle core/shell electrodes with surface-stabilized donor-acceptor chromophores, a water oxidation catalyst, and an electron-transfer mediator. For the electrode, fluorine-doped tin oxide FTO|SnO/TiO|-Org1-|1.1 nm AlO|-RuP-WOC (water oxidation catalyst) with Org1 (1-cyano-2-(4-(diphenylamino)phenyl)vinyl)phosphonic acid), the mediator RuP ([Ru(4,4-(POH)-2,2-bipyridine)(2,2-bipyridine)]), and the WOC, Ru(bda)(py(CH)P(OH)) (bda is 2,2-bipyridine-6,6-dicarboxylate with x = 3 or 10), solar excitation resulted in photocurrents of ∼500 µA/cm and quantitative O evolution at pH 4.65. Related results were obtained for other Ru(II) polypyridyl mediators. For the organic dye PP (5-(4-(dihydroxyphosphoryl)phenyl)-10,15,20-Tris(mesityl)porphyrin), solar water oxidation occurred with a driving force near 0 V.
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http://dx.doi.org/10.1073/pnas.1802903115DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6112685PMC
August 2018

Light-Driven Water Splitting Mediated by Photogenerated Bromine.

Angew Chem Int Ed Engl 2018 03 1;57(13):3449-3453. Epub 2018 Mar 1.

Department of Chemistry, University of North Carolina at Chapel Hill, Campus Box 3290, Chapel Hill, NC, 27599-3290, USA.

Light-driven water splitting was achieved using a dye-sensitized mesoporous oxide film and the oxidation of bromide (Br ) to bromine (Br ) or tribromide (Br ). The chemical oxidant (Br or Br ) is formed during illumination at the photoanode and used as a sacrificial oxidant to drive a water oxidation catalyst (WOC), here demonstrated using [Ru(bda)(pic) ], (1; pic=picoline, bda=2,2'-bipyridine-6,6'-dicarboxylate). The photochemical oxidation of bromide produces a chemical oxidant with a potential of 1.09 V vs. NHE for the Br /Br couple or 1.05 V vs. NHE for the Br /Br couple, which is sufficient to drive water oxidation at 1 (Ru ≈1.0 V vs. NHE at pH 5.6). At pH 5.6, using a 0.2 m acetate buffer containing 40 mm LiBr and the [Ru(4,4'-PO H -bpy)(bpy) ] (RuP , bpy=2,2'-bipyridine) chromophore dye on a SnO /TiO core-shell electrode resulted in a photocurrent density of around 1.2 mA cm under approximately 1 Sun illumination and a Faradaic efficiency upon addition of 1 of 77 % for oxygen evolution.
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http://dx.doi.org/10.1002/anie.201708879DOI Listing
March 2018

Polymer-based chromophore-catalyst assemblies for solar energy conversion.

Nano Converg 2017 22;4(1):37. Epub 2017 Dec 22.

Department of Chemistry, University of Texas at San Antonio, San Antonio, TX 78249 USA.

The synthesis of polymer-based assemblies for light harvesting has been motivated by the multi-chromophore antennas that play a role in natural photosynthesis for the potential use in solar conversion technologies. This review describes a general strategy for using polymer-based chromophore-catalyst assemblies for solar-driven water oxidation at a photoanode in a dye-sensitized photoelectrochemical cell (DSPEC). This report begins with a summary of the synthetic methods and fundamental photophysical studies of light harvesting polychormophores in solution which show these materials can transport excited state energy to an acceptor where charge-separation can occur. In addition, studies describing light harvesting polychromophores containing an anchoring moiety (ionic carboxylate) for covalent bounding to wide band gap mesoporous semiconductor surfaces are summarized to understand the photophysical mechanisms of directional energy flow at the interface. Finally, the performance of polychromophore/catalyst assembly-based photoanodes capable of light-driven water splitting to oxygen and hydrogen in a DSPEC are summarized.
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http://dx.doi.org/10.1186/s40580-017-0132-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5740205PMC
December 2017

Interfacial Deposition of Ru(II) Bipyridine-Dicarboxylate Complexes by Ligand Substitution for Applications in Water Oxidation Catalysis.

J Am Chem Soc 2018 01 2;140(2):719-726. Epub 2018 Jan 2.

Department of Chemistry, University of North Carolina Chapel Hill , Chapel Hill, North Carolina 27599, United States.

Water oxidation is a critical step in artificial photosynthesis and provides the protons and electrons used in reduction reactions to make solar fuels. Significant advances have been made in the area of molecular water oxidation catalysts with a notable breakthrough in the development of Ru(II) complexes that use a planar "bda" ligand (bda is 2,2'-bipyridine-6,6'-dicarboxylate). These Ru(II)(bda) complexes show lower overpotentials for driving water oxidation making them ideal for light-driven applications with a suitable chromophore. Nevertheless, synthesis of heterogeneous Ru(II)(bda) complexes remains challenging. We discuss here a new "bottom-up" synthetic method for immobilizing these catalysts at the surface of a photoanode for use in a dye-sensitized photoelectrosynthesis cell (DSPEC). The procedure provides a basis for rapidly screening the role of ligand variations at the catalyst in order to understand the impact on device performance. The best results of a water-oxidation DSPEC photoanode based on this procedure reached 1.4 mA/cm at pH 7 in 0.1 M [POH]/[POH]solution with minimal loss in catalytic behavior over 30 min, and produced an incident photon to current efficiency (IPCE) of 24.8% at 440 nm.
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http://dx.doi.org/10.1021/jacs.7b10809DOI Listing
January 2018

Mammalian odorant receptor tuning breadth persists across distinct odorant panels.

PLoS One 2017 25;12(9):e0185329. Epub 2017 Sep 25.

Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida, United States of America.

The molecular receptive range (MRR) of a mammalian odorant receptor (OR) is the set of odorant structures that activate the OR, while the distribution of these odorant structures across odor space is the tuning breadth of the OR. Variation in tuning breadth is thought to be an important property of ORs, with the MRRs of these receptors varying from narrowly to broadly tuned. However, defining the tuning breadth of an OR is a technical challenge. For practical reasons, a screening panel that broadly covers odor space must be limited to sparse coverage of the many potential structures in that space. When screened with such a panel, ORs with different odorant specificities, but equal tuning breadths, might appear to have different tuning breadths due to chance. We hypothesized that ORs would maintain their tuning breadths across distinct odorant panels. We constructed a new screening panel that was broadly distributed across an estimated odor space and contained compounds distinct from previous panels. We used this new screening panel to test several murine ORs that were previously characterized as having different tuning breadths. ORs were expressed in Xenopus laevis oocytes and assayed by two-electrode voltage clamp electrophysiology. MOR256-17, an OR previously characterized as broadly tuned, responded to nine novel compounds from our new screening panel that were structurally diverse and broadly dispersed across an estimated odor space. MOR256-22, an OR previously characterized as narrowly tuned, responded to a single novel compound that was structurally similar to a previously known ligand for this receptor. MOR174-9, a well-characterized receptor with a narrowly tuned MRR, did not respond to any novel compounds in our new panel. These results support the idea that variation in tuning breadth among these three ORs is not an artifact of the screening protocol, but is an intrinsic property of the receptors.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185329PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5612731PMC
October 2017

Mechanisms of molecular water oxidation in solution and on oxide surfaces.

Chem Soc Rev 2017 Oct;46(20):6148-6169

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.

Initial experiments on water oxidation by well-defined molecular catalysts were initiated with the goal of finding solutions to solar energy conversion. This account is a summary of research in this area by the T. J. Meyer research group. It begins with the design and characterization of the first catalyst, the blue Ru dimer, to current applications with surface-bound complexes on photoanodes for water oxidation in Dye Sensitized Photoelectrosynthesis Cells.
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http://dx.doi.org/10.1039/c7cs00465fDOI Listing
October 2017

Modulating Hole Transport in Multilayered Photocathodes with Derivatized p-Type Nickel Oxide and Molecular Assemblies for Solar-Driven Water Splitting.

J Phys Chem Lett 2017 Sep 31;8(18):4374-4379. Epub 2017 Aug 31.

Department of Chemistry, The University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.

For solar water splitting, dye-sensitized NiO photocathodes have been a primary target. Despite marginal improvement in performance, limitations remain arising from the intrinsic disadvantages of NiO and insufficient catalysis. We report here a new approach to modifying NiO photocathodes with doped NiO bilayers and an additional layer of macro-mesoporous ITO. The trilayered electrode is functionalized with a surface-attached ruthenium polypyridyl dye and a covalently bridged nickel-based hydrogen evolution catalyst. The NiO film, containing a 2% K-doped NiO inner layer and a 2% Cu-doped NiO outer layer, provides sufficient driving force for hole transport following hole injection by the molecular assembly. Upon light irradiation, the resulting photocathode generates hydrogen from water sustainably with enhanced photocurrents and a Faradaic efficiency of ∼90%. This approach highlights the value of modifying both the internal and surface structure of NiO and provides insights into a new generation of dye-sensitized photocathodes for solar-driven water splitting cells.
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http://dx.doi.org/10.1021/acs.jpclett.7b01911DOI Listing
September 2017

Plasmon-enhanced light-driven water oxidation by a dye-sensitized photoanode.

Proc Natl Acad Sci U S A 2017 09 28;114(37):9809-9813. Epub 2017 Aug 28.

Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599;

Dye-sensitized photoelectrosynthesis cells (DSPECs) provide a flexible approach for solar water splitting based on the integration of molecular light absorption and catalysis on oxide electrodes. Recent advances in this area, including the use of core/shell oxide interfacial structures and surface stabilization by atomic layer deposition, have led to improved charge-separation lifetimes and the ability to obtain substantially improved photocurrent densities. Here, we investigate the introduction of Ag nanoparticles into the core/shell structure and report that they greatly enhance light-driven water oxidation at a DSPEC photoanode. Under 1-sun illumination, Ag nanoparticle electrodes achieved high photocurrent densities, surpassing 2 mA cm with an incident photon-to-current efficiency of 31.8% under 450-nm illumination.
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http://dx.doi.org/10.1073/pnas.1708336114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5604030PMC
September 2017

Layer-by-Layer Molecular Assemblies for Dye-Sensitized Photoelectrosynthesis Cells Prepared by Atomic Layer Deposition.

J Am Chem Soc 2017 10 30;139(41):14518-14525. Epub 2017 Aug 30.

Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.

In a dye sensitized photoelectrosynthesis cell (DSPEC), the relative orientation of the catalyst and chromophore plays an important role in determining the device efficiency. Here we introduce a new, robust atomic layer deposition (ALD) procedure for the preparation of molecular chromophore-catalyst assemblies on wide bandgap semiconductors. In this procedure, solution deposited, phosphonate derivatized metal complexes on metal oxide surfaces are treated with reactive metal reagents in the gas phase by ALD to form an outer metal ion bridging group, which can bind a second phosphonate containing species from solution to establish a R-PO-O-M-O-PO-R type surface assembly. With the ALD procedure, assemblies bridged by Al(III), Sn(IV), Ti(IV), or Zr(IV) metal oxide units have been prepared. To evaluate the performance of this new type of surface assembly, intra-assembly electron transfer was investigated by transient absorption spectroscopy, and light-driven water splitting experiments under steady-state illumination were conducted. A SnO bridged assembly on SnO/TiO core/shell electrodes undergoes light-driven water oxidation with an incident photon to current efficiency (IPCE) of 17.1% at 440 nm. Light-driven water reduction with a ruthenium trisbipyridine chromophore and molecular Ni(II) catalyst on NiO films was also used to produce H. Compared to conventional solution-based procedures, the ALD approach offers significant advantages in scope and flexibility for the preparation of stable surface structures.
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http://dx.doi.org/10.1021/jacs.7b07216DOI Listing
October 2017

Polymer Chromophore-Catalyst Assembly for Solar Fuel Generation.

ACS Appl Mater Interfaces 2017 Jun 2;9(23):19529-19534. Epub 2017 Jun 2.

Department of Chemistry, University of Texas at San Antonio , One UTSA Way, San Antonio, Texas 78249, United States.

A polystyrene-based chromophore-catalyst assembly (poly-2) has been synthesized and assembled at a mesoporous metal oxide photoanode. The assembly contains water oxidation catalyst centers based on [Ru(trpy) (phenq)] (Ru-Cat) and [Ru(bpy)] derivatives (Ru-C) as chromophores (trpy= 2,2';6,2″- terpyridine, phenq = 2-(quinol-8'-yl)-1,10-phenanthroline and bpy = 2,2'-bipyridine). The photophysical and electrochemical properties of the polychromophore-oxidation catalyst assembly were investigated in solution and at the surface of mesoporous metal oxide films. The layer-by-layer (LbL) method was utilized to construct multilayer films with cationic poly-2 and anionic poly(acrylic acid) (PAA) for light-driven photochemical oxidations. Photocurrent measurements of (PAA/poly-2) LbL films on mesoporous TiO demonstrate light-driven oxidation of phenol and benzyl alcohol in aqueous solution. Interestingly, illumination of (PAA/poly-2) LbL films on a fluorine doped SnO/TiO core/shell photoanode in aqueous solution gives rise to an initial photocurrent (∼18.5 μA·cm) that is in part ascribed to light driven water oxidation.
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http://dx.doi.org/10.1021/acsami.7b05173DOI Listing
June 2017

Inner Layer Control of Performance in a Dye-Sensitized Photoelectrosynthesis Cell.

ACS Appl Mater Interfaces 2017 Oct 2;9(39):33533-33538. Epub 2017 Mar 2.

Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.

Interfacial charge transfer and core-shell structures play important roles in dye-sensitized photoelectrosynthesis cells (DSPEC) for water splitting into H and O. An important element in the design of the photoanode in these devices is a core/shell structure which controls local electron transfer dynamics. Here, we introduce a new element, an internal layer of AlO lying between the Sb:SnO/TiO layers in a core/shell electrode which can improve photocurrents by up to 300%. In these structures, the results of photocurrent, transient absorption, and linear scan voltammetry measurements point to an important role for the AlO layer in controlling internal electron transfer within the core/shell structure.
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http://dx.doi.org/10.1021/acsami.7b00225DOI Listing
October 2017

All-in-One Derivatized Tandem pn-Silicon-SnO/TiO Water Splitting Photoelectrochemical Cell.

Nano Lett 2017 04 3;17(4):2440-2446. Epub 2017 Mar 3.

Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.

Mesoporous metal oxide film electrodes consisting of derivatized 5.5 μm thick SnO films with an outer 4.3 nm shell of TiO added by atomic layer deposition (ALD) have been investigated to explore unbiased water splitting on p, n, and pn type silicon substrates. Modified electrodes were derivatized by addition of the water oxidation catalyst, [Ru(bda)(4-O(CH)POH)-pyr)], 1, (pyr = pyridine; bda = 2,2'-bipyridine-6,6'-dicarboxylate), and chromophore, [Ru(4,4'-POH-bpy) (bpy)], RuP, (bpy = 2,2'-bipyridine), which form 2:1 RuP/1 assemblies on the surface. At pH 5.7 in 0.1 M acetate buffer, these electrodes with a fluorine-doped tin oxide (FTO) back contact under ∼1 sun illumination (100 mW/cm; white light source) perform efficient water oxidation with a photocurrent of 1.5 mA/cm with an 88% Faradaic efficiency (FE) for O production at an applied bias of 600 mV versus RHE ( ACS Energy Lett. , 2016 , 1 , 231 - 236 ). The SnO/TiO-chromophore-catalyst assembly was integrated with the Si electrodes by a thin layer of titanium followed by an amorphous TiO (Ti/a-TiO) coating as an interconnect. In the integrated electrode, pn-Si-Ti/a-TiO-SnO/TiO|-2RuP/1, the pn-Si junction provided about 350 mV in added potential to the half cell. In photolysis experiments at pH 5.7 in 0.1 M acetate buffer, bias-free photocurrents approaching 100 μA/cm were obtained for water splitting, 2HO → 2H + O. The FE for water oxidation was 79% with a hydrogen efficiency of ∼100% at the Pt cathode.
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http://dx.doi.org/10.1021/acs.nanolett.7b00105DOI Listing
April 2017