Janus Nanosheets with Face-Selective Molecular Recognition Properties from DNA-Peptide Conjugates.

Chemical and functional anisotropy in Janus materials offer intriguing possibilities for constructing complex nanostructures and regulating chemical and biological reactions. Here, the authors report the fabrication of Janus nanosheets from molecular building blocks composed of two information-carrying biopolymers, DNA and peptides. Experimental and structural modeling studies reveal that DNA-peptide diblock conjugates assemble into Janus nanosheets with distinct DNA and peptide faces. The surprising level of structural control is attributed to the exclusive parallel ß-sheet formation of phenylalanine-rich peptides. This approach is extended to triblock DNA1-peptide-DNA2 conjugates, which assemble into nanosheets presenting two different DNA on opposite faces. The Janus nanosheets with independently addressable faces are utilized to organize an enzyme pair for concerted enzymatic reactions, where enhanced catalytic activities are observed. These results demonstrate that the predictable and designable peptide interaction is a promising tool for creating Janus nanostructures with regio-selective and sequence-specific molecular recognition properties.

DNA-π Amphiphiles: A Unique Building Block for the Crafting of DNA-Decorated Unilamellar Nanostructures.

The unparalleled ability of DNA to recognize its complementary strand through Watson and Crick base pairing is one of the most reliable molecular recognition events found in natural systems. This highly specific sequence information encoded in DNA enables it to be a versatile building block for bottom-up self-assembly. Hence, the decoration of functional nanostructures with information-rich DNA is extremely important as this allows the integration of other functional molecules onto the surface of the nanostructures through DNA hybridization in a highly predictable manner. DNA amphiphiles are a class of molecular hybrids where a short hydrophilic DNA is conjugated to a hydrophobic moiety. Since DNA amphiphiles comprise DNA as the hydrophilic segment, their self-assembly in aqueous medium always results in the formation of nanostructures with shell made of DNA. This clearly suggests that self-assembly of DNA amphiphiles is a straightforward strategy for the ultradense decoration of a nanostructure with DNA. However, initial attempts toward the design of DNA amphiphiles were primarily focused on long flexible hydrocarbon chains as the hydrophobic moiety, and it has been demonstrated in several examples that they typically self-assemble into DNA-decorated micelles (spherical or cylindrical). Hence, molecular level control over the self-assembly of DNA amphiphiles and achieving diverse morphologies was extremely challenging and unrealized until recently.In this Account, we summarize our recent efforts in the area of self-assembly of DNA amphiphiles and narrate the remarkable effect of the incorporation of a large π-surface as the hydrophobic domain in the self-assembly of DNA amphiphiles. Self-assembly of DNA amphiphiles with flexible hydrocarbon chains as the hydrophobic moiety is primarily driven by the hydrophobic effect. The morphology of such nanostructures is typically predicted based on the volume ratio of hydrophobic to hydrophilic segments. However, control over the self-assembly and prediction of the morphology become increasingly challenging when the hydrophobic moieties can interact with each other through other noncovalent interactions. In this Account, the unique self-assembly behaviors of DNA-π amphiphiles, where a large π-surface acts as the hydrophobe, are described. Due to the extremely strong π-π stacking in aqueous medium, the assembly of the amphiphile is found to preferably proceed in a lamellar fashion (bilayer) and hence the morphology of the nanostructures can easily be tuned by the structural modification of the π-surface. Design principles for crafting various DNA-decorated lamellar nanostructures including unilamellar vesicles, two-dimensional (2D) nanosheets, and helically twisted nanoribbons by selecting suitable π-surfaces are discussed. Unilamellar vesicular nanostructures were achieved by using linear oligo(phenylene ethynylene) (OPE) as the hydrophobic segment, where lamellar assembly undergoes folding to form unilamellar vesicles. The replacement of OPE with a strongly π-stacking hydrophobe such as hexabenzocoronene (HBC) or tetraphenylethylene (TPE) provides extremely strong π-stacking compared to OPE, which efficiently directed the 2D growth for the lamellar assembly and led to the formation of 2D nanosheets. A helical twist in the lamella was achieved by the replacement of HBC with hexaphenylbenzene (HPB), which is the twisted analogue of HBC, directing the assembly into helically twisted nanoribbons. The most beneficial structural feature of this kind of nanostructure is the extremely dense decoration of their surface with ssDNA, which can further be used for DNA-directed organization of other functional nanomaterials. By exploring this, their potential as a nanoscaffold for predefined assembly of plasmonic nanomaterials into various plasmonic 1D, 2D, and 3D nanostructures through DNA hybridization is discussed. Moreover, the design of pH-responsive DNA-based vesicles and their application as a nanocarrier for payload delivery is also demonstrated.

Updated Global Warming Potentials and Radiative Efficiencies of Halocarbons and Other Weak Atmospheric Absorbers.

Human activity has led to increased atmospheric concentrations of many gases, including halocarbons, and may lead to emissions of many more gases. Many of these gases are, on a per molecule basis, powerful greenhouse gases, although at present-day concentrations their climate effect is in the so-called weak limit (i.e., their effect scales linearly with concentration). We published a comprehensive review of the radiative efficiencies (RE) and global warming potentials (GWP) for around 200 such compounds in 2013 (Hodnebrog et al., 2013, https://doi.org/10.1002/rog.20013). Here we present updated RE and GWP values for compounds where experimental infrared absorption spectra are available. Updated numbers are based on a revised "Pinnock curve", which gives RE as a function of wave number, and now also accounts for stratospheric temperature adjustment (Shine & Myhre, 2020, https://doi.org/10.1029/2019MS001951). Further updates include the implementation of around 500 absorption spectra additional to those in the 2013 review and new atmospheric lifetimes from the literature (mainly from WMO (2019)). In total, values for 60 of the compounds previously assessed are based on additional absorption spectra, and 42 compounds have REs which differ by >10% from our previous assessment. New RE calculations are presented for more than 400 compounds in addition to the previously assessed compounds, and GWP calculations are presented for a total of around 250 compounds. Present-day radiative forcing due to halocarbons and other weak absorbers is 0.38 [0.33-0.43] W m-2, compared to 0.36 [0.32-0.40] W m-2 in IPCC AR5 (Myhre et al., 2013, https://doi.org/10.1017/CBO9781107415324.018), which is about 18% of the current CO2 forcing.

Dynamic Nanostructures from DNA-Coupled Molecules, Polymers, and Nanoparticles.

Dynamic and reconfigurable systems that can sense and react to physical and chemical signals are ubiquitous in nature and are of great interest in diverse areas of science and technology. DNA is a powerful tool for fabricating such smart materials and devices due to its programmable and responsive molecular recognition properties. For the past couple of decades, DNA-based self-assembly is actively explored to fabricate various DNA-organic and DNA-inorganic hybrid nanostructures with high-precision structural control. Building upon past development, researchers have recently begun to design and assemble dynamic nanostructures that can undergo an on-demand transformation in the structure, properties, and motion in response to various external stimuli. In this Review, recent advances in dynamic DNA nanostructures, focusing on hybrid structures fabricated from DNA-conjugated molecules, polymers, and nanoparticles, are introduced, and their potential applications and future perspectives are discussed.

DNA-Decorated, Helically Twisted Nanoribbons: A Scaffold for the Fabrication of One-Dimensional, Chiral, Plasmonic Nanostructures.

Crafting of chiral plasmonic nanostructures is extremely important and challenging. DNA-directed organization of nanoparticle on a chiral template is the most appealing strategy for this purpose. Herein, we report a supramolecular approach for the design of DNA-decorated, helically twisted nanoribbons through the amphiphilicity-driven self-assembly of a new class of amphiphiles derived from DNA and hexaphenylbenzene (HPB). The ribbons are self-assembled in a lamellar fashion through the hydrophobic interactions of HPB. The transfer of molecular chirality of ssDNA into the HPB core results in the bias of one of the chiral propeller conformations for HPB and induces a helical twist into the lamellar packing, and leads to the formation of DNA-wrapped nanoribbons with M-helicity. The potential of the ribbon to act as a reversible template for the 1D chiral organization of plasmonic nanomaterials through DNA hybridization is demonstrated.

DNA-Grafted Poly(acrylic acid) for One-Step DNA Functionalization of Iron Oxide Nanoparticles.

Here, we report one-step DNA functionalization of hydrophobic iron oxide nanoparticles (IONPs) using DNA-grafted poly(acrylic acid) (PAA- g-DNA). PAA- g-DNA was synthesized by coupling PAA to amine-modified oligonucleotides via solid-phase amide chemistry, which yielded PAA grafted with multiple DNA strands with high graft efficiencies. Synthesized PAA- g-DNA was utilized as a phase-transfer and DNA functionalization agent for hydrophobic IONPs, taking advantage of unreacted carboxylic acid groups. The resulting DNA-modified IONPs were well dispersed in aqueous solutions and possessed DNA binding properties characteristic of polyvalent DNA nanostructures, showing that this approach provides a simple one-step method for DNA functionalization of hydrophobic IONPs.

DNA-Decorated Two-Dimensional Crystalline Nanosheets.

Design and synthesis of high aspect ratio 2D nanosheets with surface having ultradense array of information-rich molecule such as DNA is extremely challenging. Herein, we report a universal strategy based on amphiphilicity-driven self-assembly for the crafting of high aspect ratio, 2D sheets that are densely surface-decorated with DNA. Microscopy and X-ray analyses have shown that the sheets are crystalline. The most unique feature of the sheets is DNA-directed surface addressability, which is demonstrated through the decoration of either faces of the sheet with gold nanoparticles through sequence-specific DNA hybridization. Our results suggest that this design strategy can be applied as a general approach for the synthesis of DNA decorated high aspect ratio sheets, which may find potential applications in materials science, drug delivery, and nanoelectronics.

A pH-Responsive DNAsome from the Self-Assembly of DNA-Phenyleneethynylene Hybrid Amphiphile.

A pH-responsive DNAsome derived from the amphiphilicity-driven self-assembly of DNA amphiphile containing C-rich DNA sequence is reported. The acidification of DNAsome induces a structural change of C-rich DNA from random coil to an i-motif structure that triggers the disassembly of DNAsome and its subsequent morphological transformation into an open entangled network. The encapsulation of a hydrophobic guest into the membrane of DNAsome and its pH-triggered release upon acidification of DNAsome is also demonstrated.

Synthesis and self-assembly of DNA-chromophore hybrid amphiphiles.

DNA based spherical nanostructures are one of the promising nanostructures for several biomedical and biotechnological applications due to their excellent biocompatibility and DNA-directed surface addressability. Herein, we report the synthesis and amphiphilicity-driven self-assembly of two classes of DNA (hydrophilic)-chromophore (hydrophobic) hybrid amphiphiles into spherical nanostructures. A solid-phase "click" chemistry based modular approach is demonstrated for the synthesis of DNA-chromophore amphiphiles. Various spectroscopic and microscopic analyses reveal the self-assembly of the amphiphiles into vesicular and micellar assemblies with the corona made of hydrophilic DNA and the hydrophobic chromophoric unit as the core of the spherical nanostructures.

Cardiac tamponade complicating purulent pericarditis due to community acquired methicilin resistant Staphylococcus aureus (CA-MRSA).

Community acquired methicillin resistant Staphylococcus aureus(CA-MRSA) is a global pathogen capable of causing life-threatening infections with increasing prevalence since the 1990s. Purulentpericarditis, characterized by accumulation of purulent fluid in the pericardial space was historically a disease of the pediatric and early adult population, but through the years the median age of diagnosis has increased from 21 to 49. Mortality rates are as high as 40% even in the treated population. We report a case of purulent pericarditis due to CA-MRSA that was complicated by cardiac tamponade. Early diagnosis and intervention proved to be life-saving. A brief review of the literature and current management options are discussed.

Self-assembly of DNA-oligo(p-phenylene-ethynylene) hybrid amphiphiles into surface-engineered vesicles with enhanced emission.

Surface-addressable nanostructures of linearly π-conjugated molecules play a crucial role in the emerging field of nanoelectronics. Herein, by using DNA as the hydrophilic segment, we demonstrate a solid-phase "click" chemistry approach for the synthesis of a series of DNA-chromophore hybrid amphiphiles and report their reversible self-assembly into surface-engineered vesicles with enhanced emission. DNA-directed surface addressability of the vesicles was demonstrated through the integration of gold nanoparticles onto the surface of the vesicles by sequence-specific DNA hybridization. This system could be converted to a supramolecular light-harvesting antenna by integrating suitable FRET acceptors onto the surface of the nanostructures. The general nature of the synthesis, surface addressability, and biocompatibility of the resulting nanostructures offer great promises for nanoelectronics, energy, and biomedical applications.

Water Is K'é: Learning from the Navajo Community to Promote Early Child Health.

BACKGROUND: Drinking water instead of sugary drinks is key to reducing health disparities. Since beverage habits are shaped by complex personal, community, and environmental factors, community input is critical to design any intervention promoting water. OBJECTIVES: We worked with community partners to design a program to promote healthy beverage habits among young Navajo children. METHODS: The socioecological model, community-based participatory methods, and strengths-based principles shaped our process. In Phase 1, multigenerational feedback taught us about the cultural importance of water and how water quality concerns influence beverage choices. In Phase 2, our Water is K'é Community Advisory Group played a leading role to design the intervention centered around cultural connection, health literacy, and water access. LESSONS LEARNED: Water is K'é was created through community partnership. Community listening and mini-pilots take time but allows the program to meet community's needs and interests. CONCLUSIONS: The solutions to health disparities lie within the community itself.

Optimal initial position and technique for the front foot contact phase of cricket fast bowling: Commonalities between individual-specific simulations of elite bowlers.

Group-based and individual-based studies in cricket fast bowling have identified common technique characteristics associated with ball release speed. The applicability of these findings to individual bowlers is often questioned, however, due to research approach limitations. This study aims to identify whether the optimal initial body position at front foot contact and subsequent technique to maximise ball release speed exhibit common characteristics for elite male cricket fast bowlers using individual-specific computer optimisations. A planar 16-segment whole-body torque-driven simulation model of the front foot contact phase of fast bowling was customised, evaluated, and the initial body position and subsequent movement pattern optimised, for ten elite male fast bowlers. The optimised techniques significantly increased ball release speed by 4.8 ± 1.3 ms-1 (13.5 ± 4.1%) and ranged between 37.8 and 42.9 ms-1, and in lower peak ground reaction forces and loading rates. Common characteristics were observed within the optimal initial body position with more extended front knees, as well as more flexion of the front and bowling arm shoulders than in current performances. Delays to the onset of trunk flexion, front arm and bowling arm shoulder extension, and wrist flexion were also common in the subsequent movement during the front foot contact phase. Lower front hip extensor and front shoulder flexor torques, as well as greater bowling shoulder extensor torques were also evident. This is useful knowledge for coach development, talent identification, and coaching practice.

Technical aspects of inguino scrotal hernia surgery in developing countries.

PURPOSE: Technical aspects of inguinoscrotal herniorrhaphy performed in low to middle income countries (LMICs) are described here to help surgeons who will operate on these challenging hernias in austere settings. METHODS: Technical considerations related to operative repair were delineated with the consensus of 7 surgeons with extensive experience in inguinoscrotal hernia repair in LMICs. Important steps and illustrations were prepared accordingly. The anatomical and pathologic differences and technical implications of operating in limited resource settings are emphasized with suggestions to approach anticipated challenges. Pre-operative evaluation, anesthetic considerations, and technical guidelines are offered in context. RESULTS: The authors have cumulatively performed over 1775 inguinoscrotal Lichtenstein operations in LMICs. While dedicated, reliable, long-term follow-up is unavailable from LMICs, one author reports outcomes with 5 year follow-up from the HerniaMed registry using the identical technique in similarly classed hernias. In 90 inguinoscrotal Lichtenstein repair patients (78.3% follow-up), there was one recurrence, low rates of chronic pain (2.2% at rest, 4.4% with activity), and low rates of reintervention (1.1%). CONCLUSION: There is a difference between inguinal hernias found in LMICs and those seen in high-income countries with larger, chronic, and more technically challenging pathology. The consequences of intra-operative complications can be catastrophic in a LMIC. Technical measures are offered to improve outcomes, avoid and manage complications, and provide optimal care to this important population.

Multicolor Conjugated Polymer Thin Films with Tunable Responsivity to Oxidative and Reductive Environments.

Dynamic colors that respond to environmental changes are of great interest for diverse areas of science and technology ranging from chemical and biological sensors to smart information display. Here, we demonstrate a multitude of responsive colors from a conjugated polymer film arising from a thin-film interference. This mechanism provides an excellent control over the thin-film color by varying the film thickness, type of substrate, and degree of polaron population and is generally applicable to various conjugated polymers for further color variation. Furthermore, multiple sets of responsive colors are achieved from a single polymer layer by patterning the underlying substrate to spatially modify the interference conditions. Using this system, we demonstrate the reversible color changes induced by an oxidative or reductive environment with color responsivity controllable with the nature of the polaron state.

Charge-Transfer-Induced Self-Assembly of Doped Conjugated Block Copolymer Nanofibers.

Here, we report charge-transfer-driven self-assembly of conjugated block copolymers (BCP) into highly doped conjugated polymer nanofibers. The ground-state integer charge transfer (ICT) between a BCP composed of poly(3-hexylthiophene) and poly(ethylene oxide) (P3HT-b-PEO) and electron-deficient 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ) induced spontaneous self-assembly of the donor and the acceptor into well-defined one-dimensional nanofibers. The presence of the PEO block plays an important role for the self-assembly by providing a polar environment that can stabilize nanoscale charge transfer (CT) assemblies. The doped nanofibers were responsive to various external stimuli such as heat, chemical, and light and exhibited efficient photothermal properties in the near-IR region. The CT-driven BCP self-assembly reported here provides a new platform for the fabrication of highly doped semiconductor nanostructures.

Shopper Purchasing Trends at Small Stores on the Navajo Nation since the Passage of the Healthy Diné Nation Act Tax: A Multi-Year Cross-sectional Survey.

Background: In 2014, the Navajo Nation passed the Healthy Diné Nation Act (HDNA), which applies an additional 2% tax on unhealthy foods and beverages and a waiver of Navajo sales tax on healthy foods and beverages. However, the HDNA's impact on purchasing behavior has not been explored. Objectives: We assessed beverage and produce purchasing trends among shoppers at small Navajo stores between 2017 and 2019, shopper characteristics associated with buying water, and whether HDNA awareness was associated with purchasing behaviors. Methods: A total of 332 shoppers at 34 stores in 2017 and 274 shoppers at 44 stores in 2019 were surveyed to assess HDNA awareness and same-day purchasing of water, sugar-sweetened beverages (SSBs), fruits, and vegetables. Hypotheses were tested using chi-square analyses and multivariate analysis. Results: Water purchasing among respondents increased significantly from 2017 to 2019 (24.4% to 32.8%; P = 0.03). Shoppers in 2019 were 1.5 times more likely to purchase water compared with 2017 (adjusted P = 0.01). There was a trend toward reduced SSB purchasing (85.8% in 2017, 80.3% in 2019, P = 0.068), while produce purchasing remained unchanged over time, at approximately 17%. Shoppers were more likely to buy water if they relied on that store for the majority of their groceries (P = 0.006) and if they did not have their own transportation to get to the store (P = 0.004). Most shoppers (56.6%) were aware of the HDNA; of these, 35.6% attributed healthier habits to the HDNA, most commonly buying more healthy drinks (49.2%), fewer unhealthy drinks (37.7%), more healthy snacks (31.1%), and fewer unhealthy snacks (26.2%). Conclusions: Shopper habits at small stores located on the Navajo Nation have shifted towards healthier purchasing from 2017 to 2019. Shoppers who were aware of the HDNA reported purchasing more healthy and fewer unhealthy food and drinks as a result of this legislation.

Peptide-Driven Shape Control of Low-Dimensional DNA Nanostructures.

We report the rational design and fabrication of unusual low-dimensional DNA nanostructures through programmable and sequence-specific peptide interactions. Dual-bioactive block copolymers composed of DNA and amino acid-based polymers (DNA-b-poly(amino acid)) were synthesized by coupling oligonucleotides to phenylalanine (Phe)-based polymers. Unlike prototypical DNA block copolymers, which typically form simple spherical micelles, DNA-b-poly(amino acid) assemble into various low-dimensional structures such as nanofibers, ribbons, and sheets through controllable amino acid interactions. Moreover, DNA-b-poly(amino acid) assemblies can undergo protease-induced fiber-to-sheet shape transformations, where the morphology change is dictated by the type of enzymes and amino acid sequences. The peptide-based self-assembly reported here provides a programmable approach to fabricate dynamic DNA assemblies with diverse and unusual low-dimensional structures.

Self-assembly of DNA-tetraphenylethylene amphiphiles into DNA-grafted nanosheets as a support for the immobilization of gold nanoparticles: a recyclable catalyst with enhanced activity.

Preventing the aggregation of NPs and their recovery are the two major hurdles in NP based catalysis. Immobilization of NPs on a support has proven to be a promising strategy to overcome these difficulties. Herein we report the design of high aspect ratio two-dimensional (2D) crystalline DNA nanosheets formed from the amphiphilicity-driven self-assembly of DNA-tetraphenylethylene amphiphiles and also demonstrate the potential of DNA nanosheets for the immobilization of catalytically active NPs. The most remarkable feature of this approach is the high loading of NPs in a non-aggregated manner, and hence exhibiting enhanced catalytic activity. Recycling of NP loaded nanosheets for several cycles without reduction in catalytic efficiency by simple ultrafiltration is also demonstrated.

Sensible heat has significantly affected the global hydrological cycle over the historical period.

Globally, latent heating associated with a change in precipitation is balanced by changes to atmospheric radiative cooling and sensible heat fluxes. Both components can be altered by climate forcing mechanisms and through climate feedbacks, but the impacts of climate forcing and feedbacks on sensible heat fluxes have received much less attention. Here we show, using a range of climate modelling results, that changes in sensible heat are the dominant contributor to the present global-mean precipitation change since preindustrial time, because the radiative impact of forcings and feedbacks approximately compensate. The model results show a dissimilar influence on sensible heat and precipitation from various drivers of climate change. Due to its strong atmospheric absorption, black carbon is found to influence the sensible heat very differently compared to other aerosols and greenhouse gases. Our results indicate that this is likely caused by differences in the impact on the lower tropospheric stability.