Highly Selective and Efficient Perdeuteration of n-Pentane via H/D Exchange Catalyzed by a Silica-Supported Hafnium-Iridium Bimetallic Complex.

A Surface OrganoMetallic Chemistry (SOMC) approach is used to prepare a novel hafnium-iridium catalyst immobilized on silica, HfIr/SiO2, featuring well-defined [≡SiOHf(CH2 tBu)2(µ-H)3IrCp*] surface sites. Unlike the monometallic analogous materials Hf/SiO2 and Ir/SiO2, which promote n-pentane deuterogenolysis through C-C bond scission, we demonstrate that under the same experimental conditions (1 bar D2, 250 °C, 3 h, 0.5 mol %), the heterobimetallic catalyst HfIr/SiO2 is highly efficient and selective for the perdeuteration of alkanes with D2, exemplified on n-pentane, without substantial deuterogenolysis (<2 % at 95 % conversion). Furthermore this HfIr/SiO2 catalyst is robust and can be re-used several times without evidence of decomposition. This represents substantial advance in catalytic H/D isotope exchange (HIE) reactions of C(sp3)-H bonds.

Taming the Lewis Superacid Al(ORF)3 (RF=C(CF3 )3 ): DFT Guided Identification of the "Stable yet Reactive" Adduct SiPr2 →Al(ORF)3 ; Its Use as ORF- Abstractor from a "Ni-ORF" complex.

A DFT study of several L→Al(ORF )3 (L=Lewis bases) adducts allowed the identification of (i Pr2 S)→Al(ORF )3 1-Si Pr2 as a "stable yet reactive" adduct. 1-Si Pr2 was shown to act as a masked Lewis superacid able to release Al(ORF )3 under mild conditions. It could be used to abstract a ORF- ligand from (bipyMe2 )Ni(ORF )2 (bipyMe2 : 6,6'-dimethyl-2,2'-dipyridyl) and generate the nickel alkoxide complex [(bipyMe2 )Ni(ORF )(i Pr2 S)]+ [(RF O)3 Al-F-Al(ORF )3 ]- 5. Ligand exchange of i Pr2 S by Ph3 P yielded [(bipyMe2 )Ni(ORF )(PPh3 )]+ [(RF O)3 Al-F-Al(ORF )3 ]- 6.

Botulinum Toxin A for Chronic Exertional Compartment Syndrome: A Retrospective Study of 16 Upper- and Lower-Limb Cases.

OBJECTIVE: To assess initial and mid-term efficacy of botulinum toxin A (BoNT-A) injections in patients with chronic exertional compartment syndrome (CECS) in the lower and upper limbs. DESIGN: Retrospective monocentric study. SETTING: A University Hospital Department of Physical Medicine and Rehabilitation. PATIENTS: Sixteen patients with CECS of the lower and upper limbs treated with BoNT-A injections (first-line treatment) were included. INTERVENTIONS, MAIN OUTCOME MEASURES: We collected data from a follow-up consultation (initial pain reduction [complete, partial, or ineffective] and specific activities triggering CECS) and a subsequent phone questionnaire (mid-term efficacy, pain recurrence, and adverse effects). RESULTS: Sixteen patients were included (median age: 25.5 years), and 68.75% reported initial efficacy (4 partial and 7 complete); 8/16 patients were able to resume the activity that triggered CECS. All the patients with initial partial efficacy had pain recurrence (median time of 2.25 months). Among patients with initial complete efficacy, 57.14% had recurrence (median time of 5 months). Minor adverse effects were observed, but with no functional impact. CONCLUSION: In 16 individuals with CECS treated with BoNT-A injections, we observed moderate efficacy without major adverse effects, but an initial improvement was often followed by recurrence, especially among those with partial initial efficacy.

Numerical simulation of universal morphogenesis of fluid interface deformations driven by radiation pressure.

We report on numerical simulation of fluid interface deformations induced by either acoustic or optical radiation pressure. This is done by solving simultaneously the scalar wave propagation equation and the two-phase flow equations using the boundary element method. Using dimensional analysis, we show that interface deformation morphogenesis is universal, i.e., depends on the same dimensionless parameters in acoustics and electromagnetics. We numerically investigate a few selected phenomena-in particular the shape of large deformations and the slenderness transition and its hysteresis-and compare with existing and novel experimental observations. Qualitative agreement between the numerical simulations and experiments is found when the mutual interaction between wave propagation and wave-induced deformations is taken into account. Our results demonstrate the leading role of the radiation pressure in morphogenesis of fluid interface deformations and the importance of the propagation-deformation interplay.

Double α,α CH bond insertion into sp3 CH2 moiety: synthesis of a Fe carbene bis-hydride dinitrogen complex.

Reduction of high spin paramagnetic complex [(κ2-P, P'-PCH2PCy)FeCl2] 2 by two electrons under N2 resulted in the formation of two isomeric low spin diamagnetic complexes 3trans and 3cis [Fe(κ3-P,C,P'-PCPCy)(H)2(N2)]. Cristallization allowed isolation of complex 3d [Fe(κ3-P,C,P'-PCPCy)(H)2]2(µ-N2), characterized by X-ray diffraction, Mössbauer and Raman spectroscopies. DFT calculations rationalized the facile double α,α CH bond insertion into a single sp3 CH2 moiety, as well as the fast exchange positions of the hydrides in the cis dihydride complex observed by NMR spectrocscopy.

Surfactant-free production of biomimetic giant unilamellar vesicles using PDMS-based microfluidics.

Microfluidic production of giant lipid vesicles presents a paradigm-shift in the development of artificial cells. While production is high-throughput and the lipid vesicles are mono-disperse compared to bulk methods, current technologies rely heavily on the addition of additives such as surfactants, glycerol and even ethanol. Here we present a microfluidic method for producing biomimetic surfactant-free and additive-free giant unilamellar vesicles. The versatile design allows for the production of vesicle sizes ranging anywhere from ~10 to 130 µm with either neutral or charged lipids, and in physiological buffer conditions. Purity, functionality, and stability of the membranes are validated by lipid diffusion, protein incorporation, and leakage assays. Usability as artificial cells is demonstrated by increasing their complexity, i.e., by encapsulating plasmids, smaller liposomes, mammalian cells, and microspheres. This robust method capable of creating truly biomimetic artificial cells in high-throughput will prove valuable for bottom-up synthetic biology and the understanding of membrane function.

Impact of a qSOFA-based triage procedure on antibiotic timing in ED patients with sepsis: A prospective interventional study.

BACKGROUND: It has not been investigated whether the quick sepsis-related organ failure assessment score (qSOFA), a new bedside tool for early sepsis detection, may help accelerating antibiotic initiation in ED patients with sepsis. METHODS: In this prospective pre/post quasi-experimental single-ED study, patients admitted with a suspected bacterial infection were managed using standard triage procedures only (baseline) or in association with qSOFA (intervention, with prioritization of patients with a qSOFA ≥ 2). RESULTS: A total of 151/328 (46.0%) and 185/350 (52.8%) patients with definite bacterial infection met the criteria for sepsis in the baseline and intervention periods, respectively. The sensitivity and specificity of a qSOFA ≥ 2 for sepsis prediction were 17.3% (95% confidence interval [CI], 13.6%-21.7%) and 98.8% (95% CI, 97.0%-99.5%). Eleven (7.3%) and 28 (13.5%) patients with sepsis in the baseline and intervention periods received a first antibiotic dose within one hour following triage (primary endpoint, absolute difference 6.2%, 95% CI [-0.5%, 12.7%], P = 0.08). The proportions of patients with sepsis receiving a first antibiotic dose within three hours following triage (39.7% [50/151] versus 36.8% [68/185], absolute difference - 2.9%, 95% CI [-13.3%, 7.3%], P = 0.65), requiring ICU admission, or dying in the hospital were similar in both periods. The median ED occupation rate at triage was 104.3% (interquartile range [IQR], 80.4%-128.3%), with a median number of 157 ED visits per day (IQR, 147-169). CONCLUSIONS: A qSOFA-based triage procedure does not improve antibiotic timing and outcomes in patients with sepsis admitted to a high-volume ED. The qSOFA value at triage was poorly sensitive for early sepsis detection. Trial registration (ClinicalTrials.gov): NCT03299894.

A modular approach for multifunctional polymersomes with controlled adhesive properties.

The bottom-up approach in synthetic biology involves the engineering of synthetic cells by designing biological and chemical building blocks, which can be combined in order to mimic cellular functions. The first step for mimicking a living cell is the design of an appropriate compartment featuring a multifunctional membrane. This is of particular interest since it allows for the selective attachment of different groups or molecules to the membrane. In this context, we report on a modular approach for polymeric vesicles, so-called polymersomes, with a multifunctional surface, namely hydroxyl, alkyne and acrylate groups. We demonstrate that the surface of the polymersome can be functionalized to facilitate imaging, via fluorescent dyes, or to improve the specific adhesion to surfaces by using a biotin functionalization. This generally applicable multifunctionality allows for the covalent integration of various molecules in the membrane of a synthetic cell.

Early/Late Heterobimetallic Tantalum/Rhodium Species Assembled Through a Novel Bifunctional NHC-OH Ligand.

The straightforward synthesis of a new unsymmetrical hydroxy-tethered N-heterocyclic carbene (NHC) ligand, HL, is presented. The free ligand exhibits an unusual OH-carbene hydrogen-bonding interaction. This OH-carbene motif was used to yield 1) the first tantalum complex displaying both a Fischer- and Schrock-type carbene ligand and 2) a unique NHC-based early/late heterobimetallic complex. More specifically, the protonolysis chemistry between the ligand's hydroxy group and imido-alkyl or alkylidene-alkyl tantalum precursor complexes yielded the rare monometallic tantalum-NHC complexes [Ta(XtBu)(L)(CH2 tBu)2 ] (X=N, CH), in which the alkoxy-carbene ligand acts as a chelate. In contrast, HL only binds to rhodium through the NHC unit in [Rh(HL)(cod)Cl] (cod=cycloocta-1,5-diene), the hydroxy pendant arm remaining unbound. This bifunctional ligand scaffold successfully promoted the assembly of rhodium/tantalum heterobimetallic complexes upon either 1) the insertion of [Rh(cod)Cl]2 into the Ta-NHC bond in [Ta(NtBu)(L)(CH2 tBu)2 ] or 2) protonolysis between the free hydroxy group in [Rh(HL)(cod)Cl] and one alkyl group in [Ta(NtBu)(CH2 tBu)3 ].

Theory of Turing Patterns on Time Varying Networks.

The process of pattern formation for a multispecies model anchored on a time varying network is studied. A nonhomogeneous perturbation superposed to an homogeneous stable fixed point can be amplified following the Turing mechanism of instability, solely instigated by the network dynamics. By properly tuning the frequency of the imposed network evolution, one can make the examined system behave as its averaged counterpart, over a finite time window. This is the key observation to derive a closed analytical prediction for the onset of the instability in the time dependent framework. Continuously and piecewise constant periodic time varying networks are analyzed, setting the framework for the proposed approach. The extension to nonperiodic settings is also discussed.

Characterization of mouthguards: Impact performance.

BACKGROUND/AIM: It is difficult to characterize the impact behavior of mouthguards on the basis of their components. Impact behavior tests should be performed on mouthguard formed to simulate their intra-oral performance. The aim of this study was to compare the impact behavior of six models of mouthguards using a standardized experimental protocol. MATERIAL AND METHODS: Four commercially available mouth-formed mouthguards (SDI™, Gel Nano™, Opro Shield Gold™ and Kipsta R300™), one mouth-formed mouthguard prototype and one custom-made mouthguard were tested. The procedures recommended by the manufacturers (injecting procedure for custom-made mouthguard and "boil-and-bite" procedures for mouth-formed mouthguards) were used to adapt five samples per model on steel jaws. Impact performances were assessed according to labial aspect thickness and maximum contact load (FMax) during impact using a drop tower. RESULTS: SDI™ and Opro Shield Gold™ had the thinnest labial aspect thickness (P<.01), followed by the Gel Nano™ and the Kipsta R300™ (P<.01) with a thickness of about 3 mm. The prototype and custom-made mouthguard were thicker (almost 4 mm). The custom-made mouthguard, the Kipsta R300™ and the prototype had the best impact performances, but the labial aspect thickness of the Kipsta R300™ was significantly lower than that of the custom-made mouthguard and the prototype. Analysis of force curves and position of the mouthguard on the impacted zone showed that the Kipsta R300™ was less well adapted. CONCLUSION: Thickness and impact performance are not sufficient criteria to characterize performance of mouthguards.

Vesicles-on-a-chip: A universal microfluidic platform for the assembly of liposomes and polymersomes.

In this study, we present a PDMS-based microfluidic platform for the fabrication of both liposomes and polymersomes. Based on a double-emulsion template formed in flow-focusing configuration, monodisperse liposomes and polymersomes are produced in a controlled manner after solvent extraction. Both types of vesicles can be formed from the exact same combination of fluids and are stable for at least three months under ambient storage conditions. By tuning the flow rates of the different fluid phases in the flow-focusing microfluidic design, the size of the liposomes and polymersomes can be varied over at least one order of magnitude. This method offers a versatile tool for future studies, e.g., involving the encapsulation of biological agents and the functionalization of artificial cell membranes, and might also be applicable for the controlled fabrication of hybrid vesicles.

Characterization of mouth-formed mouthguards: thermal performance.

This study examined whether the thermo-modeling process suits the thermal properties of the material constituting mouth-formed mouthguards (MGs). Five mouth-formed MGs were compared: four commercially available MGs (SDI™, Gel Nano™, Opro Shield Gold™, and Kipsta R300™) and one prototype. Differential scanning calorimetry was used to determine melting (T(m)) and crystallization (T(c)) temperatures and specific fusion and crystallization enthalpies (∆H(f) and ∆H(c) (J/g)). MGs were modeled with recording of vestibular flange and occlusal cushion temperatures (Toccl). Tm ranged from 45.3°C to 53.0°C and Tc ranged from 40.9°C to 48.2°C. Specific heat of fusion ranged from 40.2 J/g to 62.0 J/g. Toccl was higher than Tm for all MGs except Kipsta R300™. Guidelines provided by manufacturers may not be adapted to thermal properties of the MG material. To ensure proper thermomodeling, heating and biting durations should be adjusted.

General frost growth mechanism on solid substrates with different stiffness.

Preventing or delaying frost formation on surfaces is of significant importance in many aspects of our daily life. Despite many efforts and improvements recently achieved in the design of new icephobic materials and substrates, not all proposed solutions are universally applicable and frost formation still remains a problem in need of further flexible solutions. In this respect, we propose to take benefit from the tunable viscoelastic properties of soft polymer gel substrates, since they are known to strongly influence the dropwise condensation process of water, and to investigate condensation frosting on them. Using polymer gels with different stiffness and a hard substrate as a reference, we demonstrate their ability to delay frost formation compared to recent results reported in the literature on other solid substrates and in particular on superhydrophobic surfaces. By investigating the frost front propagation we singled out a general behavior of its dynamic evolution consisting of two processes presenting two different time scales. This general growth appears to be independent of experimental conditions as well as substrate stiffness.

Break-up dynamics of fluctuating liquid threads.

The thinning dynamics of a liquid neck before break-up, as may happen when a drop detaches from a faucet or a capillary, follows different rules and dynamic scaling laws depending on the importance of inertia, viscous stresses, or capillary forces. If now the thinning neck reaches dimensions comparable to the thermally excited interfacial fluctuations, as for nanojet break-up or the fragmentation of thermally annealed nanowires, these fluctuations should play a dominant role according to recent theory and observations. Using near-critical interfaces, we here fully characterize the universal dynamics of this thermal fluctuation-dominated regime and demonstrate that the cross-over from the classical two-fluid pinch-off scenario of a liquid thread to the fluctuation-dominated regime occurs at a well-defined neck radius proportional to the thermal length scale. Investigating satellite drop formation, we also show that at the level of the cross-over between these two regimes it is more probable to produce monodisperse droplets because fluctuation-dominated pinch-off may allow the unique situation where satellite drop formation can be inhibited. Nonetheless, the interplay between the evolution of the neck profiles from the classical to the fluctuation-dominated regime and the satellites' production remains to be clarified.

Behavior under impact of two polyvinyl acetate-polyethylene (PVA-PE) polymers and one elastomer--application to custom-made mouthguards.

A drop tower was used to identify the mechanical behaviors of two polyvinyl acetate-polyethylene (PVA-PE) polymers and one elastomer used to fabricate custom-made mouthguards. The samples were in the form of either small cubes (edge length: 20 mm) or large cubes (edge length: 30 mm). Force and strain were recorded as functions of time, enabling a stress-strain analysis to be performed. In addition, a volume energy analysis was performed. While the three materials were viscoelastic, the stress-strain analysis showed that the PVA-PE polymers were more rigid than the elastomer, i.e., the same stress was reached with a lower strain. With the volume energy analysis, the two PVA-PE polymers were found to absorb a relatively large amount of energy with small sample deformations. Results of this study suggested that the mechanical properties of PVA-PE polymers are particularly useful and relevant for the fabrication of custom-made mouthguards.

Maximal and sustained isokinetic lower-limb muscle strength in hospitalized older people.

Maximal strength decreases with aging whereas sustained strength is less affected. Strength decline may be worsened by hospitalization. The aim of this study was to estimate the maximal and sustained isokinetic muscle strength of lower limbs in hospitalized elderly subjects. We evaluated 43 hospitalized elderly subjects (86 +/- 5 years), 28 elderly community-dwelling control subjects (75.4 +/- 6.2 years), and 25 young subjects (28.2 +/- 3.7 years). Among hospitalized subjects, 30 underwent isokinetic evaluation at clinical stability (T0) and again 1 month later (T1). Maximal peak torque (MPT) of the plantarflexors was measured at 30 degrees and 60 degrees /s, and knee flexors and extensors at 90 degrees /s. Evolution of the MPT and the endurance coefficient (EC) on 20 repetitions of plantarflexion at 60 degrees /s were calculated. MPT of plantarflexors and knee flexors and extensors had improved at T1 compared with T0, in hospitalized subjects. MPT evolution and EC values during the sustained strength test revealed no decrease in strength over time in hospitalized subjects at T0 and at T1 compared with community-dwelling control subjects and young subjects. In hospitalized subjects, the absence of an initial phase of fast decrease in muscle strength, which is observed in young subjects during the sustained strength test, could explain this result. It could be related to the modifications of muscle-fiber composition described in elderly subjects and enhanced by hospitalization.

The structure and response properties of Golgi tendon organs in control and hypodynamia-hypokinesia rats.

The Golgi tendon organs (GTOs) are encapsulated mechano-receptors that, in normal conditions, monitor via Ib afferent fibers the contractile force. A 14-day period of hypodynamia, absence of weight bearing and hypokinesia, and reduction of motor activity (HH) is known to induce changes in postural muscles such as the soleus. At present, there is no data available regarding the Ib afferent feedback in normal rats (CONT group) and in rats after a hypodynamia-hypokinesia (HH group) period. Consequently, the aim of our study was to determine the HH effects on the morphological (histochemistry on gross morphology) and electrophysiological properties of the GTOs in rat soleus muscle. In the histological study, nine CONT and nineteen HH GTOs of the soleus muscle were identified. The results demonstrated that HH GTOs were morphologically similar to the CONT GTOs. Regarding the electrophysiological study, a L2-L6 laminectomy was performed under deep anesthesia (sodium pentobarbital, 60 mg kg(-1)). Responses in single Ib fibers from the L5 dorsal root to the isometric twitch and tetanic fused contractions of "in-series" motor units (MUs) were recorded. Twenty-three and twenty-eight GTO/MU pairs were studied in the CONT and HH groups, respectively. In the HH group, the Ib afferent response exhibited a decrease in dynamic peak for the high stimulation frequencies and an increase in static sensitivity for all stimulation frequencies. Our results suggest that after an HH period, the GTOs continue to fulfil their mechano-sensory function to signal the contractile force but with a higher static sensitivity.

Effects of immobilizing a single muscle on the morphology and the activation of its muscle fibers.

A single muscle of Wistar female rats, either soleus or peroneus longus, was immobilized by fixing its cut distal tendon to the bone during 8 weeks. We observed a transitory weight loss in both muscles; the mean fiber cross-sectional area (CSA) showed a reduction at day 30, followed by an increase at day 60. The time course of the activation of the immobilized muscle was evaluated by recording the chronic electromyographic (EMG) activity during short periods (1 min every other day) of treadmill locomotion. During immobilization, the integrated EMG amplitude of the soleus increased, reaching a maximum at 4 weeks, but remained close to control values during 8 weeks for the peroneus. The median frequency (MF) of the power density spectrum of the soleus EMG was not statistically different between immobilized and control muscles, while MF of the immobilized peroneus EMG was permanently higher than that of control muscles. This suggests two different modes of adaptation in motor unit command, depending on the muscle profile, which could be concomitant with the restoration of muscle fibers CSA after 8 weeks.