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Point-of-care ultrasound has evolved as an invaluable diagnostic modality and procedural guidance tool in the care of critically ill cardiac patients. Beyond focused cardiac ultrasound, additional extracardiac ultrasound modalities may provide important information at the bedside. In addition to new uses of existing modalities, such as pulsed-wave Doppler ultrasound, the development of new applications is fostered by the implementation of additional features in mid-range ultrasound machines commonly acquired for intensive care units, such as tissue elastography, speckle tracking, and contrast-enhanced ultrasound quantification software. This review explores several areas in which ultrasound imaging technology may transform care in the future. First, we review how lung ultrasound in mechanically ventilated patients can enable the personalization of ventilator parameters and help to liberate them from mechanical ventilation. Second, we review the role of venous Doppler in the assessment of organ congestion and how tissue elastography may complement this application. Finally, we explore how contrast-enhanced ultrasound could be used to assess changes in organ perfusion., L’échographie au point de service est devenue une modalité de diagnostic indispensable et un outil précieux pour orienter les interventions dans la prise en charge des patients cardiaques dans un état grave. Outre l’échographie cardiaque ciblée, d’autres modalités d’échographie extracardiaque peuvent fournir des renseignements importants au chevet du malade. En plus des nouvelles utilisations des modalités existantes, telles que l’échographie Doppler à émission pulsée, l’ajout de fonctionnalités supplémentaires aux appareils d’échographie milieu de gamme fréquemment employés dans les unités de soins intensifs, notamment des logiciels pour l’élastographie des tissus, le suivi des marqueurs acoustiques (speckle tracking) et l’échographie de contraste avec quantification, ouvre la voie à de nouvelles applications. Nous explorons ici plusieurs domaines de soins que les technologies d’imagerie par échographie pourraient révolutionner. Nous décrivons d’abord comment l’échographie des poumons d’un patient sous respiration mécanique permet de personnaliser les paramètres du respirateur afin d'accélérer le retrait de l'appareil. Nous passons ensuite en revue le rôle de l’échographie Doppler veineuse dans l’évaluation de la congestion d’un organe et expliquons comment l’élastographie pourrait apporter un complément à cette évaluation. Enfin, nous explorons le recours éventuel à l’échographie rehaussée par un agent de contraste pour évaluer les changements dans la perfusion d’un organe.

Biological environments such as the cytoplasm are comprised of many different molecules, which makes explicit modeling intractable. In the spirit of Wigner, one may be tempted to assume interactions to derive from a random distribution. Via this approximation, the system can be efficiently treated in the mean-field, and general statements about expected behavior of such systems can be made. Here, I study systems of particles interacting via random potentials, outside of mean-field approximations. These systems exhibit a phase transition temperature, under which part of the components precipitate. The nature of this transition appears to be non-universal, and to depend intimately on the underlying distribution of interactions. Above the phase transition temperature, the system can be efficiently treated using a Bethe approximation, which shows a dependence on extreme value statistics. Relaxation timescales of this system tend to be slow, but can be made arbitrarily fast by increasing the number of neighbors of each particle.

The steric stability of inorganic colloidal particles in an apolar solvent is usually described in terms of the balance between three contributions: the van der Waals attraction, the free energy of mixing, and the ligand compression. However, in the case of nanoparticles, the discrete nature of the ligand shell and the solvent has to be taken into account. Cadmium selenide nanoplatelets are a special case. They combine a weak van der Waals attraction and a large facet to particle size ratio. We use coarse grained molecular dynamics simulations of nanoplatelets in octane to demonstrate that solvation forces are strong enough to induce the formation of nanoplatelet stacks, and by that have a crucial impact on the steric stability. In particular, we demonstrate that for sufficiently large nanoplatelets, solvation forces are proportional to the interacting facet area, and their strength is intrinsically tied to the softness of the ligand shell.

Ancre dans le paysage automobile depuis plus de 60 ans, le Groupe Park Avenue a franchi ce passage du temps grâce a un modele d’affaires qui va au-dela des tendances, en creant de nouvelles regles du jeu. Alors qu’il s’apprete a passer le flambeau a la troisieme generation, Norman Hebert nous revele sa vision de la perennite et de la bonne gouvernance.

Hexahydro-3-alkyl-3H-oxazolo[3,4-a]pyridines 4-15 for the quantitative analysis of various aldehydes were obtained in good yield via the condensation reaction of 2-hydroxymethylpiperidine (2-HMP) with aldehydes under mild conditions. When acrolein is used, the bicyclic 17 was obtained. This novel compound has suitable physical characteristic for an analytical standard. The hexahydro-3-vinyl-3H-oxazolo[3,4-a]pyridine 16 can be achieve at higher temperature. Using specific conditions, a diastereomeric mixture of 18/19 and pure 18, which are both bisadducts of 2-HMP with acrolein, can be obtained. Mechanistically, a thorough 1H-NMR study did not show any evidence that the condensation reaction proceeded via an enamine. The reaction probably proceeds through an elusive hemiaminal and fleeting iminium ion, which underwent subsequent cyclisation to gave hexahydro-3-alkyl-3H-oxazolo[3,4-a]pyridines 4-16. The reaction pathways for the preparation of 4-18 are described.

Du blogue d’affaires au feminin Mots d’Elles a la presidence de la Jeune Chambre de commerce de Montreal, Deborah Cherenfant multiplie les projets et s’engage sans compter pour les causes qui la definissent. L’entrepreneure d’origine haitienne, fiere Montrealaise, raconte son parcours, ses doutes, ses espoirs, et partage sa reflexion sur les transformations consecutives a des mois de pandemie.

Lipid asymmetry in plasma membrane of eukaryotes is ubiquitous. The first measurements reported compositional asymmetry: phosphatidylethanolamine and phosphatidylserine are mostly on the cytoplasmic leafet, while phosphatidylcholine and sphingomyelin are mostly on the exoplasmic leaflet. More recent experiments using lipidomics have evidenced presence of saturation asymmetry between the two leaflets. A question that naturally arises is: why such an asymmetry? To complicate matters, it is still largely unknown in which leaflet cholesterol lies. Here, we use chemical potentials to mimic flippase proteins responsible for maintenance of compositional asymmetry in silico. We show that saturation asymmetry naturally arises as a by-product of phospholipid number asymmetry and sphingomyelin contents, thereby showing that some reported asymmetries may naturally result from others and do not necessarily require to be externally driven. We also show that, plasmalogen lipids' tendency to be highly unsaturated is also natural. Additionally, we tackle the problem of cholesterol and show that, while it is influenced by all asymmetries, the resulting cholesterol asymmetry tends to be fairly mild.

Invitee a se joindre a l’equipe d’Ivanhoe Cambridge en 2015, Nathalie Palladitcheff a quitte la France, ou elle menait deja une brillante carriere. Nommee aux commandes de la filiale immobiliere de la Caisse de depot et placement du Quebec en 2018, cette femme de reflexion et d’action a une comprehension du monde qui lui permet d’envisager un avenir durable pour le secteur immobilier.

Semiconductor nanoplatelets can possess desirable optical properties. For example, CdSe nanoplatelets show a high fluorescence quantum yield, a large one- and two-photon absorption cross section, and the ability to emit polarized light. However, their usage in devices requires control over their self-assembly, particularly the formation of stacks. The interplay of the various forces leading to stack formation in experiments remains unclear. Here, we use coarse grained molecular dynamics simulations of nanoplatelets in octane solvent to investigate the role of solvation forces in nanoplatelet interactions. We demonstrate that solvation forces resulting from solvent layering are sufficiently strong to stabilize nanoplatelet stacks. We examine the dependence of solvation forces on the nanoplatelets' ligand shell, size, and other parameters. In particular, we demonstrate that for sufficiently large nanoplatelets, solvation forces are proportional to the interacting facet area, and their strength is intrinsically tied to the softness of the ligand shell. The solvation forces exhibit an oscillatory nature; increases in their strength leads to a stronger attraction between close nanoplatelet facets and in addition to an increase in the kinetic barriers.

Cell membranes mainly consist of lipid bilayers with an actively regulated composition. The underlying processes are still poorly understood, in particular, how the hundreds of components are controlled. Cholesterol has been found to correlate with phospholipid saturation for reasons that remain unclear. To better understand the link between cell membrane regulation and chemical composition, we establish a computational framework based on chemical reaction networks, resulting in multiple semigrand canonical ensembles. By running computer simulations, we show that regulating the chemical potential of lipid species is sufficient to reproduce the experimentally observed increase in acyl tail saturation with added cholesterol. Our model proposes a different picture of lipid regulation in which components can be regulated passively instead of actively. In this picture, phospholipid acyl tail composition naturally adapts to added molecules such as cholesterol or proteins. A comparison between regulated membranes with commonly studied ternary model membranes shows stark differences: for instance, correlation lengths and viscosities observed are independent of lipid chemical affinity.

Pulmonary complications are the most common clinical manifestations of coronavirus disease (COVID-19). From recent clinical observation, two phenotypes have emerged: a low elastance or L-type and a high elastance or H-type. Clinical presentation, pathophysiology, pulmonary mechanics, radiological and ultrasound findings of these two phenotypes are different. Consequently, the therapeutic approach also varies between the two. We propose a management algorithm that combines the respiratory rate and oxygenation index with bedside lung ultrasound examination and monitoring that could help determine earlier the requirement for intubation and other surveillance of COVID-19 patients with respiratory failure.RéSUMé: Les complications pulmonaires du coronavirus (COVID-19) constituent ses manifestations cliniques les plus fréquentes. De récentes observations cliniques ont fait émerger deux phénotypes : le phénotype à élastance faible ou type L (low), et le phénotype à élastance élevée, ou type H (high). La présentation clinique, la physiopathologie, les mécanismes pulmonaires, ainsi que les observations radiologiques et échographiques de ces deux différents phénotypes sont différents. L’approche thérapeutique variera par conséquent selon le phénotype des patients atteints de COVID-19 souffrant d’insuffisance respiratoire.

Complexation of oppositely charged macromolecules is essential in several biological phenomena. Recent reports have demonstrated the importance of DNA local flexibility in governing liquid–liquid phase separation (LLPS), a ubiquitous phenomenon thought to drive membraneless cellular organization. Inspired by this, we perform coarse-grained molecular dynamics simulations to study the role of chain flexibility in the complexation of short negatively charged polyelectrolytes with long positively charged polyelectrolytes. At low ionic strengths, spontaneous segregation of chains into a condensed (polymer-rich) phase and a supernatant (polymer-depleted) phase is observed. When both the polyanion and polycation are flexible (flexible–flexible complex), denser complexes with a higher degree of structural correlation form, with fewer free chains released into the supernatant, compared to the case when the polyanion is rigid (rigid–flexible complex), in agreement with the LLPS experiments. Free chains are in rapid...

Objectives Postoperative pulmonary complications increase mortality, length, and cost of hospitalization. A better diaphragmatic strength may help face an increased work of breathing postoperatively. We, therefore, sought to determine if a low preoperative diaphragm thickening fraction (TFdi) determined by ultrasonography helped predict the occurrence of postoperative pulmonary complications after cardiac surgery independently of indicators of frailty, sarcopenia, and pulmonary function. Design Prospective observational cohort study. Setting Montreal Heart Institute, an academic cardiac surgery center in Canada. Patients Adults undergoing nonemergency cardiac surgery. Interventions We measured the preoperative thickness of the right and left hemidiaphragms at their zone of apposition at end-expiration (Tdi,ee) and peak-inspiration (Tdi,ei) with ultrasonography. Maximal thickening fraction of the diaphragm during inspiration (TFdi,max) was calculated using the following formula: TFdi,max = (Tdi,ei-Tdi,ee)/Tdi,ee. We also evaluated other potential risk factors including demographic parameters, comorbidities, Clinical Frailty Scale, grip strength, 5-meter walk test, and pulmonary function tests. We repeated TFdi,max measurements within 24 hours of extubation. The primary composite outcome of this study was the occurrence of postoperative pulmonary complications, defined as pneumonia, clinically significant atelectasis, or prolonged mechanical ventilation (> 24 hr). Measurement and main results Of the 115 patients included, 34 (29.6%) developed postoperative pulmonary complications, including two with pneumonia, four with prolonged mechanical ventilation, and 32 with clinically significant atelectasis. Those with postoperative pulmonary complications had prolonged ICU and hospital length of stays. They had a lower TFdi,max (37% [interquartile range, 31-45%] vs 44% [interquartile range, 33-58%]; p = 0.03). In multiple logistic regression, a TFdi,max less than 38.1% was associated with postoperative pulmonary complications (odds ratio, 4.9; 95% CI, 1.81-13.50; p = 0.002). All patients who developed pneumonia or prolonged mechanical ventilation had a TFdi,max less than 38.1%. Respiratory rate and diabetes were also independently associated with postoperative pulmonary complications, while pulmonary function tests and the assessed indicators of frailty and sarcopenia were not. Conclusions A low preoperative TFdi,max can help to identify patients at increased risk of postoperative pulmonary complications after cardiac surgery.

IMPORTANCE: Growing interest in microbial dysbiosis during critical illness has raised questions about the therapeutic potential of microbiome modification with probiotics. Prior randomized trials in this population suggest that probiotics reduce infection, particularly ventilator-associated pneumonia (VAP), although probiotic-associated infections have also been reported. OBJECTIVE: To evaluate the effect of Lactobacillus rhamnosus GG on preventing VAP, additional infections, and other clinically important outcomes in the intensive care unit (ICU). DESIGN, SETTING, AND PARTICIPANTS: Randomized placebo-controlled trial in 44 ICUs in Canada, the United States, and Saudi Arabia enrolling adults predicted to require mechanical ventilation for at least 72 hours. A total of 2653 patients were enrolled from October 2013 to March 2019 (final follow-up, October 2020). INTERVENTIONS: Enteral L rhamnosus GG (1 × 10(10) colony-forming units) (n = 1321) or placebo (n = 1332) twice daily in the ICU. MAIN OUTCOMES AND MEASURES: The primary outcome was VAP determined by duplicate blinded central adjudication. Secondary outcomes were other ICU-acquired infections including Clostridioides difficile infection, diarrhea, antimicrobial use, ICU and hospital length of stay, and mortality. RESULTS: Among 2653 randomized patients (mean age, 59.8 years [SD], 16.5 years), 2650 (99.9%) completed the trial (mean age, 59.8 years [SD], 16.5 years; 1063 women [40.1%.] with a mean Acute Physiology and Chronic Health Evaluation II score of 22.0 (SD, 7.8) and received the study product for a median of 9 days (IQR, 5-15 days). VAP developed among 289 of 1318 patients (21.9%) receiving probiotics vs 284 of 1332 controls (21.3%; hazard ratio [HR], 1.03 (95% CI, 0.87-1.22; P = .73, absolute difference, 0.6%, 95% CI, –2.5% to 3.7%). None of the 20 prespecified secondary outcomes, including other ICU-acquired infections, diarrhea, antimicrobial use, mortality, or length of stay showed a significant difference. Fifteen patients (1.1%) receiving probiotics vs 1 (0.1%) in the control group experienced the adverse event of L rhamnosus in a sterile site or the sole or predominant organism in a nonsterile site (odds ratio, 14.02; 95% CI, 1.79-109.58; P

Polydispersity and random sequences are ubiquitous features of polymers, and molecular dynamics simulations can help elucidate the impact of disorder in polymer systems. However, currently available packages for building polymer topologies do not enable the user to include randomness in a straightforward fashion. Here, we introduce Hoobas, a molecular builder package that easily handles polydispersity using a prototype-builder design pattern. This enables fast and easy building of systems comprised of thousands of distinct objects. It is written in the Python programming language, which ensures compatibility with a wide range of molecular dynamics packages and tools, as well as easy integration into most workflows.

Mobile particles in colloidal crystals The crystallization of nanoparticles can be controlled by functionalizing them with DNA strands that direct assembly through hybridization. The design rules for interactions between pairs of particles resemble those for ionic compounds. Inspired by molecular dynamics simulations, Girard et al. show that larger particles (∼10 nanometers in diameter) that have mutual repulsive interactions can form a stable lattice only if much smaller conjugate particles (∼1.5 nanometers in diameter) are present. These smaller particles are mobile and diffuse through the lattice, so the bonding interaction resembles the classical picture of electrons in metals. Science , this issue p. 1174

While there is a prevalent genome organization in eukaryotic cells, with heterochromatin concentrated at the nuclear periphery, anomalous cases do occur. Deviations of chromatin distribution are frequent, for example, upon aging, under malignant diseases, or even naturally in rod cells of nocturnal mammals. Using molecular dynamic simulations, we study the segregation of heterochromatin in the cell nucleus by modeling interphase chromosomes as diblock ring copolymers confined in a rigid spherical shell. In our model, heterochromatin and euchromatin are distinguished by their bending stiffnesses, while an interaction potential between the spherical shell and chromatin is used as a proxy for lamin-associated proteins. Our simulations indicate that in the absence of attractive interactions between the nuclear shell and the chromatin, the majority of heterochromatin segregates towards the nuclear interior due to depletion of less flexible heterochromatin segments from the nuclear periphery. This inverted chromatin distribution is in accord with experimental observations in rod cells. This “inversion” is also found to be independent of the heterochromatin concentration and chromosome number, and is further enhanced by additional attractive interactions between heterochromatin segments. as well as by allowing bond-crossing to emulate topoisomerase activity. The usual chromatin distribution, with heterochromatin at the periphery, can be recovered by further increasing the bending stiffness of heterochromatin segments or by turning on attractive interactions between the nuclear shell and heterochromatin. Overall, our results indicate that bending stiffness of chromatin could be a contributor to chromosome organization along with differential effects of HP1α-driven phase segregation and of loop extruders, and interactions with the nuclear envelope and topological constraints.

BackgroundData on postoperative outcomes of the COVID-19 patient population is limited. We described COVID-19 patients who underwent a surgery and the pandemic impact on surgical activities.MethodsWe conducted a multicenter cohort study between March 13 and June 192,020. We included all COVID-19 patients who underwent surgery in nine centres of the Province of Québec, the Canadian province most afflicted by the pandemic. We also included concomitant suspected COVID-19 (subsequently confirmed not to have COVID-19) patients and patients who had recovered from it. We collected data on baseline characteristics, postoperative complications and postoperative mortality. Our primary outcome was 30-day mortality. We also collected data on overall surgical activities during this first wave and during the same period in 2019.ResultsWe included 44 COVID-19 patients, 18 suspected patients, and 18 patients who had recovered from COVID-19 at time of surgery. Among the 44 COVID-19 patients, 31 surgeries (71%) were urgent and 16 (36%) were major. In these patients, pulmonary complications were frequent (25%) and 30-day mortality was high (15.9%). This mortality was higher in patients with symptoms (23.1%) compared to those without symptoms (5.6%), although not statistically significant (p = 0.118). Of the total 22,616 cases performed among participating centres during the study period, only 0.19% had COVID-19 at the time of surgery. Fewer procedures were performed during the study period compared to the same period in 2019 (44,486 cases).ConclusionIn this Canadian cohort study, postoperative 30-day mortality in COVID-19 patients undergoing surgery was high (15.9%). Although few surgeries were performed on COVID-19 patients, the pandemic impact on surgical activity volume was important.Trial registrationClinicalTrials.gov Identifier:NCT04458337.

The lipid raft hypothesis postulates that cell membranes possess some degree of lateral organization. The last decade has seen a large amount of experimental evidence for rafts. Yet, the underlying mechanism remains elusive. One hypothesis that supports rafts relies on the membrane to lie near a critical point. While supported by experimental evidence, the role of regulation is unclear. Using both a lattice model and molecular dynamics simulations, we show that lipid regulation of a many-component membrane can lead to critical behavior over a large temperature range. Across this range, the membrane displays a critical composition due to finite-size effects. This mechanism provides a rationale as to how cells tune their composition without the need for specific sensing mechanisms. It is robust and reproduces important experimentally verified biological trends: membrane-demixing temperature closely follows cell growth temperature, and the composition evolves along a critical manifold. The simplicity of the mechanism provides a strong argument in favor of the critical membrane hypothesis.SIGNIFICANCEWe show that biological regulation of a large amount of phospholipids in membranes naturally leads to a critical composition for finite-size systems. This suggests that regulating a system near a critical point is trivial for cells. These effects vanish logarithmically and therefore can be present in micron-sized systems.

The plasma membrane is the interface between cells and exterior media. While its existence has been known for a long time, organization of its constituent lipids remain a challenge. Recently, we have proposed that lipid populations may be controlled by chemical potentials of different lipid species, resulting in semi-grand canonical thermodynamic ensembles. However, the currently available molecular dynamics software packages do not allow for molecule-based chemical potentials. Here, we propose a variation on existing algorithms that allow defining chemical potentials for molecules. Additionally, we allow coupling with collective variables and show that it can be used to dynamically create asymmetric membranes. We release an implementation of the algorithm for the HOOMD-Blue molecular dynamics engine.SIGNIFICANCEWe demonstrate an algorithm that allows for simulations of molecules in the semi-grand canonical ensemble. It also allows coupling the chemical potential values to collective variable and create asymmetric membranes.

In this work, we present a joint experimental and molecular dynamics simulations effort to understand and map the crystallization behavior of polyhedral nanoparticles assembled via the interaction of DNA surface ligands. In these systems, we systematically investigated the interplay between the effects of particle core (via the particle symmetry and particle size) and ligands (via the ligand length) on crystallization behavior. This investigation revealed rich phase diagrams, previously unobserved phase transitions in polyhedral crystallization behavior, and an unexpected symmetry breaking in the ligand distribution on a particle surface. To understand these results, we introduce the concept of a zone of anisotropy, or the portion of the phase space where the anisotropy of the particle is preserved in the crystallization behavior. Through comparison of the zone of anisotropy for each particle we develop a foundational roadmap to guide future investigations.

Cell membranes mainly consist of lipid bilayers with an actively regulated composition. The underlying processes are still poorly understood, in particular how the hundreds of components are controlled. Surprisingly, in recent experiments on ectotherms, the cholesterol fraction, along with un- and mono-saturated acyl tail fractions and demixing temperatures, was shown to increase with body temperature. We establish a model based on chemical reaction networks to study regulation of membranes, resulting in multiple semi-grand canonical ensembles. By running computer simulations, we show that higher cholesterol fractions correlate with lower degrees of unsaturation, ultimately controlling the composition of lipid tails. Cholesterol also dictates membrane viscosity and regulation of the latter implies that cholesterol must increase with temperature. Overall, our model proposes a different picture of lipid regulation, where components can be passively, instead of actively, regulated.SIGNIFICANCEIn this article, we propose a regulation model where only some of the components are actively regulated between membranes, while others are naturally balanced by chemical potentials. This model provides a rationale to recently measured puzzling trends in ectotherms, that is, increased plasma membrane cholesterol fraction with temperature. Here, we show that it is directly correlated with with acyl tail saturation and order parameter correlation length. Furthermore, we highlight the relation between cholesterol and membrane viscosity.

Postoperative pulmonary complications (PPCs) occur frequently and are associated with substantial morbidity and mortality. Evidence suggests that reduction of PPCs can be accomplished by using lung-protective ventilation strategies intraoperatively, but a consensus on perioperative management has not been established. We sought to determine recommendations for lung protection for the surgical patient at an international consensus development conference. Seven experts produced 24 questions concerning preoperative assessment and intraoperative mechanical ventilation for patients at risk of developing PPCs. Six researchers assessed the literature using questions as a framework for their review. The modified Delphi method was utilised by a team of experts to produce recommendations and statements from study questions. An expert consensus was reached for 22 recommendations and four statements. The following are the highlights: (i) a dedicated score should be used for preoperative pulmonary risk evaluation; and (ii) an individualised mechanical ventilation may improve the mechanics of breathing and respiratory function, and prevent PPCs. The ventilator should initially be set to a tidal volume of 6-8 ml kg-1 predicted body weight and positive end-expiratory pressure (PEEP) 5 cm H2O. PEEP should be individualised thereafter. When recruitment manoeuvres are performed, the lowest effective pressure and shortest effective time or fewest number of breaths should be used. ispartof: BJA: British Journal of Anaesthesia vol:123 issue:6 pages:898-913 ispartof: location:England status: Published online

Controlling interactions between proteins and nanoparticles in electrolyte solutions is crucial for advancing biological sciences and biotechnology. The assembly of charged nanoparticles (NPs) and proteins in aqueous solutions can be directed by modifying the salt concentration. High concentrations of monovalent salt can induce the solubilization or crystallization of NPs and proteins. By using a multiscale coarse-grained molecular dynamics approach, we show that, due to ionic correlations in the electrolyte, NPs pairs at high monovalent salt concentrations interact via remarkably strong long-range attractions or repulsions, which can be split into three regimes depending on the surface charge densities of the NPs. NPs with zero-to-low surface charge densities interact via a long-range attraction that is stronger and has a similar range to the depletion attraction induced by polymers with radius of gyrations comparable to the NP diameter. On the other hand, moderately charged NPs with smooth surfaces as well as DNA-functionalized NPs with no possibility of hybridization between them interact via a strong repulsion of range and strength larger than the repulsion predicted by models that neglect ionic correlations, including the Derjaguin–Landau–Vervey–Overbeek (DLVO) model. Interactions between strongly charged NPs (>2 e/nm 2 ), both types smooth and DNA-functionalized NPs, show an attractive potential well at intermediate-to-high salt concentrations, which demonstrates that electrolytes can induce aggregation of strongly charged NPs. Our work provides an improved understanding of the role of ionic correlations in NP assembly and design rules to utilize the salting-out process to crystallize NPs.

Directed crystallization of a large variety of nanoparticles, including proteins, via DNA hybridization kinetics has led to unique materials with a broad range of crystal symmetries. The nanoparticles are functionalized with DNA chains that link neighboring functionalized units. The shape of the nanoparticle, the DNA length, the sequence of the hybridizing DNA linker, and the grafting density determine the crystal symmetries and lattice spacing. By carefully selecting these parameters, one can, in principle, achieve all the symmetries found for both atomic and colloidal crystals of asymmetric shapes as well as new symmetries and can drive transitions between them. A scale-accurate coarse-grained model with explicit DNA chains provides the design parameters, including the degree of hybridization, to achieve specific crystal structures. The model also provides surface energy values to determine the shape of defect-free single crystals with macroscopic anisotropic properties, which has potential for the fabrication of materials with specific optical and mechanical properties.

Background Liver transplant recipients suffer many postoperative complications. Few studies evaluated the effects of fluid management on these complications. We conducted an observational cohort study to evaluate the association between intraoperative fluid balance and postoperative acute kidney injury (AKI) and other postoperative complications. Methods We included consecutive adult liver transplant recipients who had their surgery between July 2008 and December 2017. Our exposure was intraoperative fluid balance, and our primary outcome was the grade of AKI at 48 hours after surgery. Our secondary outcomes were the grade of AKI at 7 days, the need for postoperative renal replacement therapy, postoperative red blood cell transfusions, time to first extubation, time to discharge from the intensive care unit (ICU), and 1-year survival. Every analysis was adjusted for potential confounders. Results We included 532 transplantations in 492 patients. We observed no effect of fluid balance on either 48-hour AKI, 7-day AKI, or on the need for postoperative renal replacement therapy after adjustments for confounders. A higher fluid balance increased the time to ICU discharge, and increased the risk of dying (hazard ratio = 1.21 [1.04,1.40]). Conclusions We observed no association between intraoperative fluid balance and postoperative AKI. Fluid balance was associated with longer time to ICU discharge and lower survival. This study provides insight that might inform the design of a clinical trial on fluid management strategies in this population.

Background During general anaesthesia, most patients develop atelectasis, which promotes postoperative pulmonary complications. RCTs that investigated perioperative lung protection have failed to reduce postoperative pulmonary complications consistently. Ultrasound imaging could help confirm the effects of different protective ventilatory strategies, but this has not been tested in trials. The objective of this study was to use ultrasonography to evaluate whether lung-protective ventilation measures reduce perioperative atelectasis. Methods We conducted a prospective, randomised patient- and assessor-blinded controlled trial in women undergoing open gynaecological surgery. Subjects were randomised to either lung protection or zero end-expiratory pressure (ZEEP; with no recruitment manoeuvres [RMs]). Lung protection entailed PEEP (7 cm H2O) and RMs every 30 min. Lung ultrasonography was undertaken at five predefined time points. The primary outcome was the difference in lung ultrasonography score (LUS) between groups before emergence; a lower LUS indicates better lung aeration. Results We recruited 45 women (34–85 yr old). Women randomised to lung protection had lower mean (standard deviation) LUS before emergence (6.1 [3.7]), compared with women randomised to ZEEP (11.7 [3.9]; 95% confidence interval for the difference between group means [–7.9 to –3.2]; P Conclusions As assessed by lung ultrasonography, intraoperative PEEP/RMs decreased aeration loss during general anaesthesia. However, similar degrees of aeration loss were observed after tracheal extubation regardless of intraoperative ventilatory strategy. Clinical trial registration NCT02055807.

The programmed crystallization of particles into low-symmetry lattices represents a major synthetic challenge in the field of colloidal crystal engineering. Herein, we report an approach to realizing such structures that relies on a library of low-symmetry Au nanoparticles, with synthetically adjustable dimensions and tunable aspect ratios. When modified with DNA ligands and used as building blocks for colloidal crystal engineering, these structures enable one to expand the types of accessible lattices and to answer mechanistic questions about phase transitions that break crystal symmetry. Indeed, crystals formed from a library of elongated rhombic dodecahedra yield a rich phase space, including low-symmetry lattices (body-centered tetragonal and hexagonal planar). Molecular dynamics simulations corroborate and provide insight into the origin of these phase transitions. In particular, we identify an unexpected asymmetry in the DNA shell, distinct from both the particle and lattice symmetries, which enables directional, nonclose-packed interactions.