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Journal of the American Chemical Society Oct 2015We report that an exceptionally large volume of highly ordered arrays (single grains) on the order of millimeters in scale can be rapidly created through a unique innate...
We report that an exceptionally large volume of highly ordered arrays (single grains) on the order of millimeters in scale can be rapidly created through a unique innate guiding mechanism of brush block copolymers (BBCPs). The grain volume is over 10(9) times larger than that of typical self-assembled linear BCPs (LBCPs). The use of strong interactions between nanoparticles (NPs) and BBCPs enables high loadings of functional materials, up to 76 wt % (46 vol %) in the target domain, while maintaining excellent long-range order. Overall, this work provides a simple method to precisely control the spatial orientation of functionalities at nanometer length scales over macroscopic volumes, thereby enabling the production of hybrid materials for many important applications.
PubMed: 26389793
DOI: 10.1021/jacs.5b08632 -
Sensors (Basel, Switzerland) Apr 2022A review of technological solutions and advances in the framework of a Vertical Heterogeneous Network (VHetNet) integrating satellite, airborne and terrestrial networks... (Review)
Review
A review of technological solutions and advances in the framework of a Vertical Heterogeneous Network (VHetNet) integrating satellite, airborne and terrestrial networks is presented. The disruptive features and challenges offered by a fruitful cooperation among these segments within a ubiquitous and seamless wireless connectivity are described. The available technologies and the key research directions for achieving global wireless coverage by considering all these layers are thoroughly discussed. Emphasis is placed on the available antenna systems in satellite, airborne and ground layers by highlighting strengths and weakness and by providing some interesting trends in research. A summary of the most suitable applicative scenarios for future 6G wireless communications are finally illustrated.
Topics: Technology; Wireless Technology
PubMed: 35590826
DOI: 10.3390/s22093136 -
ACS Applied Materials & Interfaces Sep 2019Mosquito compound eyes are elaborate multifunctional hierarchical structures. The presence of ordered curved features spanning length scales of nanometers to millimeters...
Mosquito compound eyes are elaborate multifunctional hierarchical structures. The presence of ordered curved features spanning length scales of nanometers to millimeters provides the mosquito eye with a wide field of view, an infinite depth of field, and antifogging properties. Developing bio-inspired compound lenses is challenging because of the need to mimic all characteristic curvatures along with their functionalities. Herein, we show how the curvature inherent to nanoparticles, emulsion droplets, and liquid marbles can be employed to mimic the hierarchical structure and functionality of mosquito compound eyes. At the nanometer to micrometer length scale we employ nanoparticle-stabilized emulsion droplets of photocurable oil to form microlenses with nanoscale surface features. After polymerization, the microlenses form a monolayer on an oil droplet to create an optically clear, millimeter scale, liquid marble that functions as a compound lens. We characterize the optical and surface properties of the compound lenses and find that they reproduce the functionality of the mosquito eye. Additionally, we exploit the mobility and reconfigurability of liquid marbles to create arrays (centimeter scale) of compound lenses and other types of functional lenses such as the Janus lens that magnifies the image acquired by the compound lens. Simple and scalable methods to create compound lenses could aid in the development of miniaturized advanced vision systems.
PubMed: 31465195
DOI: 10.1021/acsami.9b12738 -
Proceedings of the National Academy of... Dec 2022Liquid mobility is ubiquitous in nature, with droplets emerging at all size scales, and artificial surfaces have been designed to mimic such mobility over the past few...
Liquid mobility is ubiquitous in nature, with droplets emerging at all size scales, and artificial surfaces have been designed to mimic such mobility over the past few decades. Meanwhile, millimeter-sized droplets are frequently used for wettability characterization, even with facial mask applications, although these applications have a droplet-size target range that spans from millimeters to aerosols measuring less than a few micrometers. Unlike large droplets, microdroplets can interact sensitively with the fibers they contact with and are prone to evaporation. However, wetting behaviors at the single-microfiber level remain poorly understood. Herein, we characterized the wettability of fibrous layers, which revealed that a multiscale landscape of droplets ranged from the millimeter to the micrometer scale. The contact angle (CA) values of small droplets on pristine fibrous media showed sudden decrements, especially on a single microfiber, owing to the lack of air cushions for the tiny droplets. Moreover, droplets easily adhered to the pristine layer during droplet impact tests and then yielding widespread areas of contamination on the microfibers. To resolve this, we carved nanowalls on the pristine fibers by plasma etching, which effectively suppressed such wetting phenomena. Significantly, the resulting topographies of the microfibers managed the dynamic wettability of droplets at the multiscale, which reduced the probability of contamination with impact droplets and suppressed the wetting transition upon evaporation. These findings for the dynamic wettability of fibrous media will be useful in the fight against infectious droplets.
Topics: Wettability; Masks; Physical Phenomena
PubMed: 36469787
DOI: 10.1073/pnas.2209586119 -
Science Advances Sep 2023Liquid entrainment with a solid architecture passing through the fluid-fluid interface is ubiquitous and widely used in industrial processes as a liquid transfer method....
Liquid entrainment with a solid architecture passing through the fluid-fluid interface is ubiquitous and widely used in industrial processes as a liquid transfer method. Besides liquid properties, solid structures play a core role in entrainment. Although the influence of its macroscopic curvatures and microscale roughness has attracted years of research, the effect and potential of the commonly seen millimetric structures have not been sufficiently explored and exploited. Here, we demonstrate enhanced liquid entrainment on the millimetric structured surface by the co-effect of viscosity and capillarity for sustained liquid transfer of small deviation, including high-quantity uptake and practically operational drainage with small and relatively uniform droplet dripping time of varied liquid viscosities. With the overall process of viscous-capillary entrainment, we achieve stable cyclical arrayed liquid transport, showing its potential for sustained liquid transfer in intractable situations in laboratory, industry, and even daily life.
PubMed: 37682994
DOI: 10.1126/sciadv.adi5990 -
The Cochrane Database of Systematic... Oct 2007Taurine is the most abundant free amino acid in breast milk. Evidence exists that taurine has important roles in intestinal fat absorption, hepatic function, and... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Taurine is the most abundant free amino acid in breast milk. Evidence exists that taurine has important roles in intestinal fat absorption, hepatic function, and auditory and visual development in preterm or low birth weight infants. Observational data suggest that relative taurine deficiency during the neonatal period is associated with adverse long-term neurodevelopmental outcomes in preterm infants. Current standard practice is to supplement formula milk and parenteral nutrition solutions with taurine.
OBJECTIVES
To assess the effect of providing supplemental taurine for enterally or parenterally fed preterm or low birth weight infants on growth and development.
SEARCH STRATEGY
The standard search strategy of the Cochrane Neonatal Review Group was used. This included searches of the Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library, Issue 2, 2007), MEDLINE (1966 - June 2007), EMBASE (1980 - June 2007), conference proceedings, and previous reviews.
SELECTION CRITERIA
Randomised or quasi-randomised controlled trials that compared taurine supplementation versus no supplementation in preterm or low birth weight newborn infants.
DATA COLLECTION AND ANALYSIS
Data were extracted using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by two review authors, and synthesis of data using relative risk, risk difference and weighted mean difference.
MAIN RESULTS
Nine small trials were identified. In total, 189 infants participated. Most participants were greater than 30 weeks gestational age at birth and were clinically stable. In eight of the studies, taurine was given enterally with formula milk. Only one small trial assessed parenteral taurine supplementation. Taurine supplementation increased intestinal fat absorption [weighted mean difference 4.0 (95% confidence interval 1.4, 6.6) percent of intake]. However, meta-analyses did not reveal any statistically significant effects on growth parameters assessed during the neonatal period or until three to four months chronological age [rate of weight gain: weighted mean difference -0.25 (95% confidence interval -1.16, 0.66) grams/kilogram/day; change in length: weighted mean difference 0.37 (95% confidence interval -0.23, 0.98) millimetres/week; change in head circumference: weighted mean difference 0.15 (95% confidence interval -0.19, 0.50) millimeters/week]. There are very limited data on the effect on neonatal mortality or morbidities, and no data on long-term growth or neurological outcomes.
AUTHORS' CONCLUSIONS
Despite that lack of evidence of benefit from randomised controlled trials, it is likely that taurine will continue to be added to formula milks and parenteral nutrition solutions used for feeding preterm and low birth weight infants given the putative association of taurine deficiency with various adverse outcomes. Further randomised controlled trials of taurine supplementation versus no supplementation in preterm or low birth weight infants are unlikely to be viewed as a research priority, but there may be issues related to dose or duration of supplementation in specific subgroups of infants that merit further research.
Topics: Enteral Nutrition; Humans; Infant Formula; Infant, Low Birth Weight; Infant, Newborn; Infant, Premature; Randomized Controlled Trials as Topic; Taurine
PubMed: 17943882
DOI: 10.1002/14651858.CD006072.pub2 -
The American Journal of Surgical... Mar 2002Despite improved surgical treatment strategies for rectal cancer, 5-15% of all patients will develop local recurrences. After conservative surgery, circumferential... (Clinical Trial)
Clinical Trial Comparative Study Randomized Controlled Trial
Despite improved surgical treatment strategies for rectal cancer, 5-15% of all patients will develop local recurrences. After conservative surgery, circumferential resection margin (CRM) involvement is a strong predictor of local recurrence. The consequences of a positive CRM after total mesorectal excision (TME) have not been evaluated in a large patient population. In a nationwide randomized multicenter trial comparing preoperative radiotherapy and TME versus TME alone for rectal cancer, CRM involvement was determined according to trial protocol. In this study we analyze the criteria by which the CRM needs to be assessed to predict local recurrence for nonirradiated patients (n = 656, median follow-up 35 months). CRM involvement is a strong predictor for local recurrence after TME. A margin of < or = 2 mm is associated with a local recurrence risk of 16% compared with 5.8% in patients with more mesorectal tissue surrounding the tumor (p <0.0001). In addition, patients with margins < or = 1 mm have an increased risk for distant metastases (37.6% vs 12.7%, p <0.0001) as well as shorter survival. The prognostic value of CRM involvement is independent of TNM classification. Accurate determination of CRM in rectal cancer is important for determination of local recurrence risk, which might subsequently be prevented by additional therapy. In contrast to earlier studies, we show that an increased risk is present when margins are < or = 2 mm.
Topics: Adult; Aged; Aged, 80 and over; Combined Modality Therapy; Female; Humans; Lymph Nodes; Male; Middle Aged; Multivariate Analysis; Neoplasm Metastasis; Neoplasm Recurrence, Local; Prospective Studies; Rectal Neoplasms
PubMed: 11859207
DOI: 10.1097/00000478-200203000-00009 -
PloS One 2018To develop a novel approach for highly accelerated Magnetic Resonance Fingerprinting (MRF) acquisition.
OBJECT
To develop a novel approach for highly accelerated Magnetic Resonance Fingerprinting (MRF) acquisition.
MATERIALS AND METHODS
The proposed method combines parallel imaging, soft-gating and key-hole approaches to highly accelerate MRF acquisition. Slowly varying flip angles (FA), commonly used during MRF acquisition, lead to a smooth change in the signal contrast of consecutive time-point images. This assumption enables sharing of high frequency data between different time-points, similar to what is done in some dynamic MR imaging methods such as key-hole. The proposed approach exploits this information using a SOft-weighted key-HOle (MRF-SOHO) reconstruction to achieve high acceleration factors and/or increased resolution without compromising image quality or increasing scan time. MRF-SOHO was validated on a standard T1/T2 phantom and in in-vivo brain acquisitions reconstructing T1, T2 and proton density parametric maps.
RESULTS
Accelerated MRF-SOHO using less data per time-point and less time-point images enabled a considerable reduction in scan time (up to 4.6x), while obtaining similar T1 and T2 accuracy and precision when compared to zero-filled MRF reconstruction. For the same number of spokes and time-points, the proposed method yielded an enhanced performance in quantifying parameters than the zero-filled MRF reconstruction, which was verified with 2, 1 and 0.7 (sub-millimetre) resolutions.
CONCLUSION
The proposed MRF-SOHO enabled a 4.6x scan time reduction for an in-plane spatial resolution of 2x2 mm2 when compared to zero-filled MRF and enabled sub-millimetric (0.7x0.7 mm2) resolution MRF.
Topics: Brain; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging; Pattern Recognition, Automated; Phantoms, Imaging; Time Factors
PubMed: 30092033
DOI: 10.1371/journal.pone.0201808 -
The Review of Scientific Instruments Nov 2023Mechanical property characterization of micro-scale material systems, such as free-standing films or small diameter wires (<20 µm), often requires expensive,...
Mechanical property characterization of micro-scale material systems, such as free-standing films or small diameter wires (<20 µm), often requires expensive, specialized test systems. Conventional tensile test systems are usually designed for millimeter scale specimens with the force sensing capability of >1N while microdevice-based testers are intended for micro-/nano-scale specimens operating within a much smaller force range of <10 mN. This disparity leaves a technology gap in reliable and cost-effective characterization methods for specimens at the intermediate scale. In this research, we introduce the cost-effective and all-in-one tensile testing system with a built-in force sensor, self-aligning mechanisms, and loading frames. Owing to the advantages of 3D printing technologies, the ranges of force measurement (0.001-1 N) and displacement (up to tens of millimeters) of our 3D printed tensile tester can be readily tailored to suit specific material dimension and types. We have conducted a finite element simulation to identify the potential sources of the measurement error during tensile testing and addressed the dominant errors by simply modifying the dimension/design of the loading frames. As a proof-of-concept demonstration, we have characterized fine copper (Cu) wires with 10-25 µm diameters by the 3D printed tensile tester and confirmed that the measured mechanical properties match with the known values of bulk Cu. Our work shows that the proposed 3D printed tensile testing system offers a cost-efficient and easily accessible testing method for accurate mechanical characterization of specimens with cross-sectional dimensions of the order of tens of micrometers.
PubMed: 37934034
DOI: 10.1063/5.0172671 -
Science Robotics Dec 2018The ability to climb greatly increases the reachable workspace of terrestrial robots, improving their utility for inspection and exploration tasks. This is particularly...
The ability to climb greatly increases the reachable workspace of terrestrial robots, improving their utility for inspection and exploration tasks. This is particularly desirable for small (millimeter-scale) legged robots operating in confined environments. This paper presents a 1.48-gram and 4.5-centimeter-long tethered quadrupedal microrobot, the Harvard Ambulatory MicroRobot with Electroadhesion (HAMR-E). The design of HAMR-E enables precise leg motions and voltage-controlled electroadhesion for repeatable and reliable climbing of inverted and vertical surfaces. The innovations that enable this behavior are an integrated leg structure with electroadhesive pads and passive alignment ankles and a parametric tripedal crawling gait. At a relatively low adhesion voltage of 250 volts, HAMR-E achieves speeds up to 1.2 (4.6) millimeters per second and can ambulate for a maximum of 215 (162) steps during vertical (inverted) locomotion. Furthermore, HAMR-E still retains the ability for high-speed locomotion at 140 millimeters per second on horizontal surfaces. As a demonstration of its potential for industrial applications, such as in situ inspection of high-value assets, we show that HAMR-E is capable of achieving open-loop, inverted locomotion inside a curved portion of a commercial jet engine.
PubMed: 33141691
DOI: 10.1126/scirobotics.aau3038