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1.
Health Promot Pract ; : 15248399241234058, 2024 Feb 28.
Article in English | MEDLINE | ID: mdl-38415651

ABSTRACT

Anti-Asian and anti-immigrant sentiment has surged in the country in the last 3 years. Food insecurity is also on the rise; in our local needs assessment of n = 1,270 Asian American adults in New York City, accessing food was cited as the number 1 priority among those who needed help. Finally, racial discrimination and food access are related to fear of being attacked-driving feelings of safety and therefore willingness to travel for food. To combat these narratives and leveraging pivots by our community partners, we implemented a community-supported agriculture pilot program (n = 38) to assess whether culturally appropriate food access can improve diet and foster cross-cultural learning among immigrant families in Brooklyn, NY. Over a 20-week period from June to October 2022, participants received Chinese-specific produce and nutrition education. Participants reported eating more and a greater variety of vegetables and had higher vegetable intake measured via skin carotenoid scores. This pilot may inform the adaptation of nutrition interventions to reduce inequities in chronic diseases in immigrant communities.

2.
Epidemiol Rev ; 45(1): 127-139, 2023 Dec 20.
Article in English | MEDLINE | ID: mdl-37045807

ABSTRACT

Improving race and ethnicity (hereafter, race/ethnicity) data quality is imperative to ensure underserved populations are represented in data sets used to identify health disparities and inform health care policy. We performed a scoping review of methods that retrospectively improve race/ethnicity classification in secondary data sets. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, searches were conducted in the MEDLINE, Embase, and Web of Science Core Collection databases in July 2022. A total of 2 441 abstracts were dually screened, 453 full-text articles were reviewed, and 120 articles were included. Study characteristics were extracted and described in a narrative analysis. Six main method types for improving race/ethnicity data were identified: expert review (n = 9; 8%), name lists (n = 27, 23%), name algorithms (n = 55, 46%), machine learning (n = 14, 12%), data linkage (n = 9, 8%), and other (n = 6, 5%). The main racial/ethnic groups targeted for classification were Asian (n = 56, 47%) and White (n = 51, 43%). Some form of validation evaluation was included in 86 articles (72%). We discuss the strengths and limitations of different method types and potential harms of identified methods. Innovative methods are needed to better identify racial/ethnic subgroups and further validation studies. Accurately collecting and reporting disaggregated data by race/ethnicity are critical to address the systematic missingness of relevant demographic data that can erroneously guide policymaking and hinder the effectiveness of health care practices and intervention.


Subject(s)
Data Accuracy , Ethnicity , Racial Groups , Humans , Medically Underserved Area , Retrospective Studies
3.
Cancer Causes Control ; 34(12): 1043-1058, 2023 Dec.
Article in English | MEDLINE | ID: mdl-37481755

ABSTRACT

PURPOSE: To apply principles of group model building (GMB), a participatory systems science approach, to identify barriers and opportunities for collective impact around nutrition programming to reduce cancer risk for immigrant communities in an urban environment. METHODS: We convened four in-person workshops applying GMB with nine community partners to generate causal loop diagrams (CLDs)-a visual representation of hypothesized causal relationships between variables and feedback structures within a system. GMB workshops prompted participants to collaboratively identify programmatic goals and challenges related to (1) community gardening, (2) nutrition education, (3) food assistance programs, and (4) community-supported agriculture. Participants then attended a plenary session to integrate findings from all workshops and identify cross-cutting ideas for collective action. RESULTS: Several multilevel barriers to nutrition programming emerged: (1) food policies center the diets and practices of White Americans and inhibit culturally tailored food guidelines and funding for culturally appropriate nutrition education; (2) the lack of culturally tailored nutrition education in communities is a missed opportunity for fostering pride in immigrant food culture and sustainment of traditional food practices; and (3) the limited availability of traditional ethnic produce in food assistance programs serving historically marginalized immigrant communities increases food waste and worsens food insecurity. CONCLUSION: Emergent themes coalesced around the need to embed cultural tailoring into all levels of the food system, while also considering other characteristics of communities being reached (e.g., language needs). These efforts require coordinated actions related to food policy and advocacy, to better institutionalize these practices within the nutrition space.


Subject(s)
Food , Refuse Disposal , Humans , Nutritional Status , Diet , Nutrition Policy
4.
J Hand Surg Am ; 46(2): 106-113, 2021 02.
Article in English | MEDLINE | ID: mdl-32950317

ABSTRACT

PURPOSE: This study examined the effect of low-profile volar rim plates (VR), proximally placed standard variable-angle locking plates (pVA-LCP), and distally placed standard variable-angle locking plates (dVA-LCP) on the flexor pollicis longus (FPL) tendon in a cadaver model. We hypothesized that tendons from the VR and pVA-LCP groups would exhibit similar contact pressures, wear patterns, and post-fatigue testing mechanical properties, whereas dVA-LCP tendons would exhibit higher contact pressures, increased tendon wear patterns, and decreased mechanical properties. METHODS: Nine matched pairs of cadaveric specimens were used in this study. Thin-film pressure sensors were used to measure the initial contact loads between plates and FPL tendons. Specimens were cyclically loaded for 10,000 cycles by actuating the FPL tendon. Cycled tendons were harvested, photographed with a stereomicroscope, and graded for wear on a Likert scale by 5 observers who were blinded to the study protocol. Uniaxial tensile testing measured mechanical properties of the tendon: ultimate failure load, ultimate stress, percent stress relaxation, elastic modulus, and stiffness. RESULTS: With regard to the cadaveric FPL tendon, VR and dVA-LCP had increased contact pressure and tendon wear compared with pVA-LCP. There were no significant differences in contact pressure or tendon wear between dVA-LCP and VR. There was no major difference in the tested mechanical properties of the FPL tendon among any of the groups. CONCLUSIONS: Plates placed directly on or beyond the volar rim demonstrate increased contact pressures and increased tendon wear in a cadaveric model. CLINICAL RELEVANCE: Although low-profile plates allow for fixation of smaller volar fragments in the distal radius, they cause substantial contact with the FPL tendon, which may rupture if the plate is not removed.


Subject(s)
Radius Fractures , Tendon Injuries , Bone Plates , Cadaver , Fracture Fixation, Internal , Humans , Tendon Injuries/surgery , Tendons/surgery
5.
Eur Radiol ; 30(9): 4918-4929, 2020 Sep.
Article in English | MEDLINE | ID: mdl-32342182

ABSTRACT

OBJECTIVES: Computed tomography (CT) pulmonary angiography is widely used in patients with suspected pulmonary hypertension (PH). However, the diagnostic and prognostic significance remains unclear. The aim of this study was to (a) build a diagnostic CT model and (b) test its prognostic significance. METHODS: Consecutive patients with suspected PH undergoing routine CT pulmonary angiography and right heart catheterisation (RHC) were identified. Axial and reconstructed images were used to derive CT metrics. Multivariate regression analysis was performed in the derivation cohort to identify a diagnostic CT model to predict mPAP ≥ 25 mmHg (the existing ESC guideline definition of PH) and > 20 mmHg (the new threshold proposed at the 6th World Symposium on PH). In the validation cohort, sensitivity, specificity and compromise CT thresholds were identified with receiver operating characteristic (ROC) analysis. The prognostic value of the CT model was assessed using Kaplan-Meier analysis. RESULTS: Between 2012 and 2016, 491 patients were identified. In the derivation cohort (n = 247), a CT model was identified including pulmonary artery diameter, right ventricular outflow tract thickness, septal angle and left ventricular area. In the validation cohort (n = 244), the model was diagnostic, with an area under the ROC curve of 0.94/0.91 for mPAP ≥ 25/> 20 mmHg respectively. In the validation cohort, 93 patients died; mean follow-up was 42 months. The diagnostic thresholds for the CT model were prognostic, log rank, all p < 0.01. DISCUSSION: In suspected PH, a diagnostic CT model had diagnostic and prognostic utility. KEY POINTS: • Diagnostic CT models have high diagnostic accuracy in a tertiary referral population of with suspected PH. • Diagnostic CT models stratify patients by mortality in suspected PH.


Subject(s)
Computed Tomography Angiography/methods , Hypertension, Pulmonary/diagnosis , Pulmonary Artery/diagnostic imaging , Pulmonary Wedge Pressure/physiology , Aged , Cardiac Catheterization/methods , Female , Humans , Hypertension, Pulmonary/physiopathology , Lung/physiopathology , Male , Middle Aged , Pulmonary Artery/physiopathology , ROC Curve
7.
J Shoulder Elbow Surg ; 28(6): 1183-1192, 2019 Jun.
Article in English | MEDLINE | ID: mdl-30770316

ABSTRACT

BACKGROUND: Locked plating of displaced proximal humeral fractures is common, but rates of subacromial impingement remain high. This study used a multidisciplinary approach to elucidate the relationships between common surgical parameters, anatomic variability, and the likelihood of plate impingement. METHODS: The experiment was completed in 3 phases. First, a controlled in vitro experiment was conducted to simulate impingement. Second, a dynamic in silico musculoskeletal model modeled changes to implant geometry, surgical techniques, and acromial anatomy, where a collision detection algorithm was used to simulate impingement. Finally, in vivo shoulder kinematics were recorded for 9 activities of daily living. Motions that created a high likelihood of impingement were identified. RESULTS: Of simulated impingement events, 73.9% occurred when the plate was moved proximally, and 84% occurred when acromial tilt was 20° or 25°. Simulations of impingement occurred at cross-body adduction angles between 10° and 50°. Impingement occurred at an average of 162.0° ± 14.8° abduction with 10 mm distal plate placement, whereas the average was 72.1° ± 11.4° with 10 mm proximal placement. A patient may encounter these shoulder angles when performing activities such as combing one's hair, lifting an object overhead, and reaching behind one's head. DISCUSSION AND CONCLUSION: Proximal implant placement and decreases in acromial tilt play major roles in the likelihood of impingement, whereas plate thickness and humeral head center of rotation should also be considered. Careful preoperative planning that includes these factors could help guide operative decision making and improve clinical outcomes.


Subject(s)
Bone Plates/adverse effects , Fracture Fixation, Internal/instrumentation , Shoulder Fractures/surgery , Shoulder Impingement Syndrome/etiology , Acromion/anatomy & histology , Activities of Daily Living , Aged , Biomechanical Phenomena , Cadaver , Computer Simulation , Female , Fracture Fixation, Internal/adverse effects , Fracture Fixation, Internal/methods , Humans , Humeral Head , Male , Movement , Rotation , Shoulder Joint/physiopathology , Shoulder Joint/surgery , Young Adult
8.
Small ; 14(20): e1703808, 2018 May.
Article in English | MEDLINE | ID: mdl-29659147

ABSTRACT

The mechanisms of carrier transport in the cross-plane crystal orientation of transition metal dichalcogenides are examined. The study of in-plane electronic properties of these van der Waals compounds has been the main research focus in recent years. However, the distinctive physical anisotropies, short-channel physics, and tunability of cross layer interactions can make the study of their electronic properties along the out-of-plane crystal orientation valuable. Here, the out-of-plane carrier transport mechanisms in niobium diselenide and hafnium disulfide are explored as two broadly different representative materials. Temperature-dependent current-voltage measurements are preformed to examine the mechanisms involved. First principles simulations and a tunneling model are used to understand these results and quantify the barrier height and hopping distance properties. Using Raman spectroscopy, the thermal response of the chemical bonds is directly explored and the insight into the van der Waals gap properties is acquired. These results indicate that the distinct cross-plane carrier transport characteristics of the two materials are a result of material thermal properties and thermally mediated transport of carriers through the van der Waals gaps. Exploring the cross-plane electron transport, the exciting physics involved is unraveled and potential new avenues for the electronic applications of van der Waals layers are inspired.

9.
Nephrol Dial Transplant ; 33(6): 923-934, 2018 06 01.
Article in English | MEDLINE | ID: mdl-29244159

ABSTRACT

Background: Chronic kidney disease (CKD) patients have deficient levels of glutathione peroxidase-3 (GPx3). We hypothesized that GPx3 deficiency may lead to cardiovascular disease in the presence of chronic kidney disease due to an accumulation of reactive oxygen species and decreased microvascular perfusion of the myocardium. Methods. To isolate the exclusive effect of GPx3 deficiency in kidney disease-induced cardiac disease, we studied the GPx3 knockout mouse strain (GPx3-/-) in the setting of surgery-induced CKD. Results. Ribonucleic acid (RNA) microarray screening of non-stimulated GPx3-/- heart tissue show increased expression of genes associated with cardiomyopathy including myh7, plac9, serpine1 and cd74 compared with wild-type (WT) controls. GPx3-/- mice underwent surgically induced renal mass reduction to generate a model of CKD. GPx3-/- + CKD mice underwent echocardiography 4 weeks after injury. Fractional shortening (FS) was decreased to 32.9 ± 5.8% in GPx3-/- + CKD compared to 62.0% ± 10.3 in WT + CKD (P < 0.001). Platelet aggregates were increased in the myocardium of GPx3-/- + CKD. Asymmetric dimethylarginine (ADMA) levels were increased in both GPx3-/- + CKD and WT+ CKD. ADMA stimulated spontaneous platelet aggregation more quickly in washed platelets from GPx3-/-. In vitro platelet aggregation was enhanced in samples from GPx3-/- + CKD. Platelet aggregation in GPx3-/- + CKD samples was mitigated after in vivo administration of ebselen, a glutathione peroxidase mimetic. FS improved in GPx3-/- + CKD mice after ebselen treatment. Conclusion: These results suggest GPx3 deficiency is a substantive contributing factor to the development of kidney disease-induced cardiac disease.


Subject(s)
Disease Models, Animal , Glutathione Peroxidase/physiology , Heart Diseases/etiology , Platelet Aggregation , Renal Insufficiency, Chronic/complications , Thrombosis/etiology , Ventricular Dysfunction, Left/etiology , Animals , Arginine/analogs & derivatives , Arginine/metabolism , Heart Diseases/metabolism , Heart Diseases/pathology , Mice , Mice, Knockout , Reactive Oxygen Species/metabolism , Renal Insufficiency, Chronic/metabolism , Renal Insufficiency, Chronic/pathology , Thrombosis/metabolism , Thrombosis/pathology , Ventricular Dysfunction, Left/metabolism , Ventricular Dysfunction, Left/pathology
11.
J Org Chem ; 82(9): 4640-4653, 2017 05 05.
Article in English | MEDLINE | ID: mdl-28440078

ABSTRACT

Following the discovery that the guaianolide natural product eupalinilide E promotes the expansion of hematopoietic stem and progenitor cells; the development of a synthetic route to provide laboratory access to the natural product became a priority. Exploration of multiple synthetic routes yielded an approach that has permitted a scalable synthesis of the natural product. Two routes that failed to access eupalinilide E were triaged either as a result of providing an incorrect diastereomer or due to lack of synthetic efficiency. The successful strategy relied on late-stage allylic oxidations at two separate positions of the molecule, which significantly increased the breadth of reactions that could be used to this point. Subsequent to C-H bond oxidation, adaptations of existing chemical transformations were required to permit chemoselective reduction and oxidation reactions. These transformations included a modified Luche reduction and a selective homoallylic alcohol epoxidation.


Subject(s)
Sesquiterpenes/chemical synthesis , Laboratories , Oxidation-Reduction
12.
J Youth Adolesc ; 46(5): 917-930, 2017 05.
Article in English | MEDLINE | ID: mdl-28361196

ABSTRACT

By examining the relationship between trans identity, bathroom safety and wellbeing among high school students, this article empirically investigates how educational institutions operate as sites through which gender is negotiated in ways that are consequential for trans youth. We draw cross-sectional survey data, from a multi-school climate survey (n = 1046) conducted in the Midwestern United States, to examine three aspects of high school students' wellbeing: safety at school, self-esteem, and grades. The sample included students in 9th-12th grade who identified as trans (9.2%) and cisgender (41.2% boys, 49.6% girls), as well as LGBQ (21.6%) and heterosexual (78.4%). Most respondents were monoracial white (65.8%), monoracial Black (12.4%), and multiracial (14.1%). Using mediation and moderation linear regression models, we show that feeling safe using school facilities helps to explain widespread inequalities between trans and cisgender students. Based on these results, we suggest that in order to address disparities in educational outcomes between trans and cisgender students, as well as to improve student wellbeing in general, policies and practices need to ensure that all students have the right to safely access bathrooms and school facilities.


Subject(s)
Gender Identity , Self Concept , Sexuality/psychology , Students/psychology , Toilet Facilities , Adolescent , Cross-Sectional Studies , Female , Humans , Male , Midwestern United States , Schools , Sexuality/statistics & numerical data , Socioeconomic Factors , Students/statistics & numerical data , Surveys and Questionnaires
13.
J Am Chem Soc ; 138(18): 6068-73, 2016 05 11.
Article in English | MEDLINE | ID: mdl-27096704

ABSTRACT

Improving the ex vivo and in vivo production of hematopoietic stem and progenitor cells (HSPCs) has the potential to address the short supply of these cells that are used in the treatment of various blood diseases and disorders. Eupalinilide E promotes the expansion of human HSPCs and inhibits subsequent differentiation, leading to increased numbers of clinically useful cells. This natural product represents an important tool to uncover new methods to drive expansion while inhibiting differentiation. However, in the process of examining these effects, which occur through a novel mechanism, the natural product was consumed, which limited additional investigation. To provide renewed and improved access to eupalinilide E, a laboratory synthesis has been developed and is reported herein. The synthetic route can access >400 mg in a single batch, employing reactions conducted on useful scales in a single vessel. Key transformations enabling the approach include a diastereoselective borylative enyne cyclization and a late-stage double allylic C-H oxidation as well as adapted Luche reduction and aluminum-mediated epoxidation reactions to maximize the synthetic efficiency. Retesting of the synthetic eupalinilide E confirmed the compound's ability to expand HSPCs and inhibit differentiation.


Subject(s)
Hematopoietic Stem Cells/drug effects , Sesquiterpenes/chemical synthesis , Sesquiterpenes/pharmacology , Stem Cells/drug effects , Aluminum/chemistry , Antigens, CD34/biosynthesis , Cell Differentiation , Cell Proliferation , Hematopoietic Stem Cells/metabolism , Humans , Oxidation-Reduction , Stem Cells/metabolism , Stereoisomerism
14.
Am J Kidney Dis ; 67(6): 984-8, 2016 Jun.
Article in English | MEDLINE | ID: mdl-26786296

ABSTRACT

Ferumoxytol is a superparamagnetic iron oxide particle encapsulated by a semisynthetic carbohydrate with properties that can be used by the nephrologist for diagnosis and therapy. Ferumoxytol is approved by the US Food and Drug Administration for treating iron deficiency anemia in the setting of chronic kidney disease, but not for clinical diagnostic imaging. It has gained appeal as a magnetic resonance imaging contrast agent in patients with estimated glomerular filtration rates < 30mL/min/1.73m(2) in whom gadolinium-based contrast magnetic resonance imaging agents are relatively contraindicated because of the association with gadolinium deposition and nephrogenic systemic fibrosis. Ferumoxytol metabolism is not dependent on kidney function, but rather is removed from the circulation by the reticuloendothelial system of the liver, spleen, and bone marrow. Additionally, the prolonged intravascular half-life (>14 hours) of ferumoxytol allows for longer image acquisition and repeat imaging, if necessary. In patients with contraindications for gadolinium contrast agents, ferumoxytol is an alternative agent for vascular assessment, including patency and course.


Subject(s)
Contrast Media , Ferrosoferric Oxide , Magnetic Resonance Imaging/methods , Renal Insufficiency, Chronic/diagnostic imaging , Adult , Female , Humans , Radiographic Image Enhancement , Severity of Illness Index
15.
Clin Orthop Relat Res ; 474(4): 1028-37, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26671040

ABSTRACT

BACKGROUND: Disruption of the periosteum has been used to explain overgrowth after long bone fractures. Clinically, various periosteal procedures have been reported to accelerate growth with varied results. Differences between procedures and study populations, in these prior studies, make drawing conclusions regarding their effectiveness difficult. QUESTIONS/PURPOSES: The purpose of this study was to (1) determine if all reported periosteal procedures accelerate growth and increase the length of bones; (2) study the relative duration of these growth-accelerating effects at two time points; and (3) identify the periosteal procedure that results in the most growth. METHODS: Periosteal stripping (N = 8), periosteal transection (N = 8), periosteal resection (N = 8), (and) full periosteal release (N = 8) were performed on the tibiae of skeletally immature rabbits. Tibiae were collected 2 weeks postoperatively. The tibiae of additional cohorts of periosteal transection (N = 8), periosteal resection (N = 8), full periosteal release (N = 8), and repetitive periosteal transection (N = 8) were collected 8 weeks postoperatively. The contralateral tibiae served as an operative sham control in all cohorts. Fluorochrome bone labeling was used to measure growth rates, whereas high-resolution Faxitron imaging was performed to measure tibial lengths. Comparisons were then made between (1) experimental and sham controls; and (2) different procedures. Eight additional nonsurgical animals were included as age-matched controls. RESULTS: Growth (in microns) was accelerated at the proximal tibial physis on the tibia undergoing the periosteal surgical procedures versus the contralateral control limb after the transection (411 ± 27 versus 347 ± 18, p < 0.001 [mean ± SD]), resection (401 ± 33 versus 337 ± 31, p < 0.001), and full periosteal release (362 ± 45 versus 307 ± 33, p < 0.001), 2 weeks after the index procedure. Conversely, the periosteal stripping cohort trended toward less growth (344 ± 35) than the controls (356 ± 25; p = 0.08). No differences were found between limbs in the nonoperative controls. Tibial lengths for the experimental tibiae were longer at 2 weeks in the transection (1.6 ± 0.4 mm, p < 0.001), resection (1.6 ± 0.9 mm, p = 0.03), and full periosteal release (1.7 ± 0.5 mm, p < 0.001), whereas negligible differences were found between the tibiae of the nonoperative controls (0.13 ± 0.7 mm, p = 0.8) and stripping cohorts (0.10 ± 0.6 mm, p = 0.7). At 8 weeks, growth acceleration ceased at the proximal tibial physes in the transection cohort (174 ± 11 versus 176 ± 21, p = 0.8), and the control limbs actually grew faster than the experimental limbs after resection (194 ± 24 versus 178 ± 23, p = 0.02) and full periosteal release (193 ± 16 versus 175 ± 19, p < 0.01) cohorts. Growth rates were increased over control limbs, only in the repetitive transection cohort (190 ± 30 versus 169 ± 19, p = 0.01) at 8 weeks. Tibial lengths for the experimental tibiae remained longer at 8 weeks in the transection (1.4 ± 0.70 mm, p < 0.001), resection (2.2 ± 0.82 mm, p < 0.001), full periosteal release (1.6 ± 0.42 mm, p < 0.001), and repetitive periosteal transection (3.3 ± 1.1 mm, p < 0.001), whereas negligible differences were found between the tibiae of the nonoperative controls (-0.08 ± 0.58 mm, p = 0.8). Comparing the procedures at 2 weeks postoperatively, no differences were found in tibial lengths among the transection (2.1% ± 0.5% increase), resection (2.1% ± 1.1% increase), and full periosteal release (2.1% ± 0.6 %); however, all three demonstrated greater increased growth when compared with the stripping cohort (-0.10% ± 0.7%; p < 0.05). At 8 weeks no differences could be found between increased tibial lengths among the transection (1.5% ± 0.7%), resection (2.3% ± 0.9%), and full periosteal release (1.7% ± 0.4%). The repetitive transection produced the greatest over length increase (3.5% ± 1%), and this was greater than the acceleration generated by the single resection (p < 0.001) or the full periosteal release (p = 0.001). All four demonstrated an increase greater than the nonoperative control (0.09% ± 0.6%; p < 0.05). CONCLUSIONS: Transection of the longitudinally oriented periosteal fibers appears critical to accelerate growth in a rabbit model. CLINICAL RELEVANCE: These findings in an animal model support previous claims that limb overgrowth occurs as the result of periosteal disruption. Based on these findings in rabbits, we believe that less invasive procedures like periosteal transection are a promising avenue to explore in humans; clinical studies should seek to determine whether it is equally effective as more invasive procedures and its role as an adjunct to guided growth or distraction osteogenesis.


Subject(s)
Bone Development , Orthopedic Procedures/methods , Osteotomy , Periosteum/surgery , Tibia/growth & development , Tibia/surgery , Age Factors , Animals , Female , Models, Animal , Orthopedic Procedures/adverse effects , Osteotomy/adverse effects , Rabbits , Radiography , Tibia/diagnostic imaging , Time Factors
16.
Nano Lett ; 15(11): 7211-6, 2015 Nov 11.
Article in English | MEDLINE | ID: mdl-26468687

ABSTRACT

In this work, we leverage graphene's unique tunable Seebeck coefficient for the demonstration of a graphene-based thermal imaging system. By integrating graphene based photothermo-electric detectors with micromachined silicon nitride membranes, we are able to achieve room temperature responsivities on the order of ~7-9 V/W (at λ = 10.6 µm), with a time constant of ~23 ms. The large responsivities, due to the combination of thermal isolation and broadband infrared absorption from the underlying SiN membrane, have enabled detection as well as stand-off imaging of an incoherent blackbody target (300-500 K). By comparing the fundamental achievable performance of these graphene-based thermopiles with standard thermocouple materials, we extrapolate that graphene's high carrier mobility can enable improved performances with respect to two main figures of merit for infrared detectors: detectivity (>8 × 10(8) cm Hz(1/2) W(-1)) and noise equivalent temperature difference (<100 mK). Furthermore, even average graphene carrier mobility (<1000 cm(2) V(-1) s(-1)) is still sufficient to detect the emitted thermal radiation from a human target.

17.
Kidney Int ; 87(4): 771-83, 2015 Apr.
Article in English | MEDLINE | ID: mdl-25469849

ABSTRACT

Vascular inflammation is a major contributor to the severity of acute kidney injury. In the context of vasospasm-independent reperfusion injury we studied the potential anti-inflammatory role of the Gα-related RGS protein, RGS4. Transgenic RGS4 mice were resistant to 25 min injury, although post-ischemic renal arteriolar diameter was equal to the wild type early after injury. A 10 min unilateral injury was performed to study reperfusion without vasospasm. Eighteen hours after injury, blood flow was decreased in the inner cortex of wild-type mice with preservation of tubular architecture. Angiotensin II levels in the kidneys of wild-type and transgenic mice were elevated in a sub-vasoconstrictive range 12 and 18 h after injury. Angiotensin II stimulated pre-glomerular vascular smooth muscle cells (VSMCs) to secrete the macrophage chemoattractant RANTES, a process decreased by angiotensin II R2 (AT2) inhibition. However, RANTES increased when RGS4 expression was suppressed implicating Gα protein activation in an AT2-RGS4-dependent pathway. RGS4 function, specific to VSMC, was tested in a conditional VSMC-specific RGS4 knockout showing high macrophage density by T2 MRI compared with transgenic and non-transgenic mice after the 10 min injury. Arteriolar diameter of this knockout was unchanged at successive time points after injury. Thus, RGS4 expression, specific to renal VSMC, inhibits angiotensin II-mediated cytokine signaling and macrophage recruitment during reperfusion, distinct from vasomotor regulation.


Subject(s)
Angiotensin II/metabolism , Kidney Cortex/blood supply , Myocytes, Smooth Muscle/metabolism , RGS Proteins/metabolism , Reperfusion Injury/metabolism , Vasoconstriction , Angiotensin II/pharmacology , Angiotensin II Type 2 Receptor Blockers/pharmacology , Animals , Aorta/cytology , Arterioles/physiopathology , Cells, Cultured , Chemokine CCL5/metabolism , Humans , Kidney Cortex/metabolism , Macrophages , Mice , Mice, Knockout , Muscle, Smooth, Vascular/cytology , Myocytes, Smooth Muscle/drug effects , RGS Proteins/genetics , Receptor, Angiotensin, Type 2/metabolism , Renal Circulation , Reperfusion Injury/pathology , Reperfusion Injury/physiopathology , Signal Transduction
18.
Nano Lett ; 14(11): 6424-9, 2014 Nov 12.
Article in English | MEDLINE | ID: mdl-25347787

ABSTRACT

Few-layer and thin film forms of layered black phosphorus (BP) have recently emerged as a promising material for applications in high performance nanoelectronics and infrared optoelectronics. Layered BP thin films offer a moderate bandgap of around 0.3 eV and high carrier mobility, which lead to transistors with decent on-off ratios and high on-state current densities. Here, we demonstrate the gigahertz frequency operation of BP field-effect transistors for the first time. The BP transistors demonstrated here show respectable current saturation with an on-off ratio that exceeds 2 × 10(3). We achieved a current density in excess of 270 mA/mm and DC transconductance above 180 mS/mm for hole conduction. Using standard high frequency characterization techniques, we measured a short-circuit current-gain cutoff frequency fT of 12 GHz and a maximum oscillation frequency fmax of 20 GHz in 300 nm channel length devices. BP devices may offer advantages over graphene transistors for high frequency electronics in terms of voltage and power gain due to the good current saturation properties arising from their finite bandgap, thus can be considered as a promising candidate for the future high performance thin film electronics technology for operation in the multi-GHz frequency range and beyond.

19.
Mol Syst Des Eng ; 9(9): 912-919, 2024 Aug 27.
Article in English | MEDLINE | ID: mdl-39205672

ABSTRACT

3D Voronoi scaffolds are widely applied in the field of additive manufacturing as they are known for their light weight structural resilience and share many topological similarities to various natural (bone, tumours, lymph node) and synthetic environments (foam, functionally gradient porous materials). Unfortunately, the structural design features that promote these topological similarities (such as the number of vertices) are often unpredictable and require the trial and error of varying design features to achieve the desired 3D Voronoi structure. This article provides a toolkit, consisting of equations, based on over 12 000 3D Voronoi structures. These equations allow design features, such as the number of generating points (G), to be efficiently and accurately predicted based on the desired structural parameters (within ±3G). Based on these equations we are proposing, to the best of our knowledge, two new mathematical conjectures that relate the number of vertices or edges, and the average edge length to G in Voronoi structures. These equations have been validated for a wide range of parameter values and Voronoi network sizes. A design code is provided allowing any of over 12 000 structures to be selected, easily adjusted based on user requirements, and 3D printed. Biomedical case studies relevant to T-cell culturing, bone scaffolds and kidney tumours are presented to illustrate the design code.

20.
Biotechnol J ; 19(1): e2300359, 2024 Jan.
Article in English | MEDLINE | ID: mdl-37986209

ABSTRACT

Physical networks are ubiquitous in nature, but many of them possess a complex organizational structure that is difficult to recapitulate in artificial systems. This is especially the case in biomedical and tissue engineering, where the microstructural details of 3D cell scaffolds are important. Studies of biological networks-such as fibroblastic reticular cell (FRC) networks-have revealed the crucial role of network topology in a range of biological functions. However, cell scaffolds are rarely analyzed, or designed, using graph theory. To understand how networks affect adhered cells, 3D culture platforms capturing the complex topological properties of biologically relevant networks would be needed. In this work, we took inspiration from the small-world organization (high clustering and low path length) of FRC networks to design cell scaffolds. An algorithmic toolset was created to generate the networks and process them to improve their 3D printability. We employed tools from graph theory to show that the networks were small-world (omega factor, ω = -0.10 ± 0.02; small-world propensity, SWP = 0.74 ± 0.01). 3D microprinting was employed to physicalize networks as scaffolds, which supported the survival of FRCs. This work, therefore, represents a bioinspired, graph theory-driven approach to control the networks of microscale cell niches.


Subject(s)
Lymph Nodes , Tissue Scaffolds
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