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In this systematic study, we attempt to thoroughly understand the aggregation mechanism of conductive carbon black in aqueous dispersing medium and optimize the formulation of suspension electrodes for aqueous sodium–ion semisolid flow battery applications. For the first time, we present branched micelle solution as an electrolyte that introduces the widest electrochemical stability window of 3.5 V, from –3 to + 0.5 V vs. Ag/AgCl, with relatively low viscosity, rendering it as promising aqueous dispersing medium for suspension electrodes (anolytes). The simultaneous rheo-electrical measurements revealed that the aggregation of conductive ketjenblack (KB) particles was controlled by the electrostatic repulsion forces that doubly originate from the inter-aggregate soft interaction and bulk micelle interactions. This remarkable interaction rendered the dispersions electrically percolated at low carbon content (0.9 wt%) and importantly able to conserve the electrical conductivity under extremely high shear rates. Under the quiescent conditions, the percolated KB dispersion could sustain higher load of active material (up to 30 wt% Na2Ti3O7 as an active material) without severe influence on the rigidity (rheological plateau modulus G0) and electrical conductivity (Σ) of the suspensions. These promising findings propound further investigation for the electrochemical performance of these aqueous sodium–ion suspension electrodes under flow conditions. The authors wish to thank staff at the Central Laboratories Unit, Qatar University for accomplishing SEM and Raman spectroscopy, and the staff at the Center for Advanced Materials, Qatar University for performing the XRD measurements. Mohamed Youssry would like to acknowledge the financial support from Qatar University [Grant No. QUST-1-CAS-2020-6]. Open Access funding provided by the Qatar National Library is acknowledged.

In this study, we demonstrated a controllable synthesis of sodium titanates (Na2Ti6O13 and Na2Ti3O7) using simple mechanochemical (dry ball milling) method. Although the titanates were obtained after calcination, however, the milling speed and duration control the phase type, crystallinity, purity and morphology of the as-synthesized materials. At low milling speed (200 rpm), cuboid-like Na2Ti6O13 nanostructures were the dominant phase, where the purity and crystallinity enhanced for prolonged milling duration (20 h). The nanorod-like Na2Ti3O7 phase is the dominant phase at higher milling speeds (≥300 rpm) with minor traces of Na2Ti6O13 phase that disappeared at prolonged milling. In contrast to wet chemical methods, no byproducts such as titanic acids or unreacted materials were detected in the materials synthesized by the mechanochemical method.

Objective The aim of this study was to compare the effectiveness of two different protocols, labetalol with magnesium sulfate versus hydralazine with magnesium sulfate intravenous infusion with respect to their impact on maternal and fetal hemodynamics in severe preeclampsia. Patients and methods In this prospective comparative randomized study, a total of 50 pregnant women in severe preeclampsia with gestational age ≥ 32 weeks were randomly recruited into two groups. Group A: 25 patients received labetalol with magnesium sulfate, and group B: 25 patients received hydralazine with magnesium sulfate by intravenous infusion in an escalating manner according to response until the target blood pressure ≤ 145/95 mmHg was achieved. Blood pressure, maternal heart rate, fetal heart rate, and Doppler ultrasound indices of umbilical and middle cerebral arteries were studied before and after treatment. Results A significant reduction of the maternal blood pressure was achieved in both groups, with significant reduction of maternal heart rate in group A. No significant changes in the umbilical and middle cerebral arteries pulsatility index, resistance index, and systolic/diastolic ratio before and after treatment were noted in both groups. Conclusion We concluded that both labetalol and hydralazine intravenous infusion regimens are well tolerated and effective in controlling severe hypertension in pregnant women with severe preeclampsia in combination with magnesium sulfate. Both drugs are reassuring as they are not related to any significant changes in fetoplacental circulation. Fetal heart rate did not change significantly after treatment in both groups.

Objective: The aim of our study is to assess the prevalence of anemia in pregnant women, and to evaluate the effect of severity of anemia on maternal and perinatal outcome. Methods: This retrospective cohort study was conducted at the Department of Obstetrics and Gynecology from hospital records. Study population of all pregnant women who had delivered in our hospital after twenty weeks gestation between July 2014 and December 2016. Results: A total of 2654 pregnant women fulfilled the inclusion criteria, 42% were anemic, 83.3% mild anemia group (I) which represents the majority of patients and 16.7% moderate to severe anemia group (II). The majority of cases were due to iron deficiency anemia 92.8%, while 7.2% were due to sickle cell trait, B-thalassemia intermedia, and other causes. The incidence of postpartum hemorrhage, cesarean delivery, and infections was significantly higher in group II compared to group I (5.4%, 40.3%, 3.8% Vs, 2.9%, 31.0%, 2.0%; p = 0.007, 0.041, 0.043 respectively). Low Apgar score, preterm labor, and low birth weight babies were significantly higher in group II compared to group I (11.8%, 12.9%, 11.3% Vs 8.7%, 9.0%, 7.4%; p = 0.034, 0.046, 0.032). Conclusions: This study clarified that anemia is prevalent among pregnant women particularly mild anemia. Early diagnosis and treatment from first trimester has an essential role in managing maternal anemia and it reflects directly on the perinatal outcome. Prematurity, low birth weight infants, and postpartum hemorrhage are the commonest maternal and neonatal complications.

Objective: The aim of this study is to evaluate vitamin B12, folate, and homocysteine status in pregnant women in the third trimester of pregnancy and their relationship to fetal birth weight and their correlation to corresponding neonatal cord blood levels, and in addition, to evaluate the possibility of maternal serum homocysteine level as a predictor of low birth weight infants. Subjects and Methods: In this cross-sectional study, a total of two hundred pregnant women in third trimester (≥28 weeks) were recruited. After a detailed obstetrical and medical history, and clinical assessment, participants were subdivided into two groups: Group (A)—pregnant women who delivered average birth weight (ABW) infants and Group (B) for those who delivered low birth weight (LBW) infants between completed 37 and 42 weeks. Results: Vitamin B12 deficiency was observed in 24.1% of the total cohort. The mean vitamin B12 level was significantly lower in group (B) compared to group (A) (195.2 ± 38.9 vs. 225.9 ± 66.59 respectively P = 0.008). The mean level of homocysteine for women in group (B) was significantly higher than those determined from women in group (A) (9.10 ± 5.9 vs. 7.6 ± 3.83 respectively, P = 0.042). On the other hand, the mean folate levels showed statistically insignificant differences between both groups. The mean cord vitamin B12 level was significantly lower in LBW infants in comparison to ABW infants (277 ± 61.93 vs. 312.03 ± 81.87 respectively, P = 0.015), while the mean level of cord homocysteine for LBW infants was significantly higher than those levels determined from ABW infants (7.9 ± 3.79 vs. 6.6 ± 2.09 respectively P = 0.0049). Conclusion: Maternal micronutrients particularly cobalamin deficiency could be significant risk for LBW infants. Hyperhomocysteinemia has been shown to be a predictor for adverse pregnancy outcomes particularly LBW.

The aqueous dispersions of a special type of carbon black (CB) in 1 M lithium bis(trifluoromethanesulfonimide) electrolyte is mainly controlled by the affinity of the aqueous electrolyte towards the CB particles rather than the particle size. In spite of its small particle size (30 nm), this type of CB forms a three-dimensional open network which is rheologically and electrically percolated at a relatively high threshold (2.0 wt%) with enhanced rheological and electrical properties. At this percolating threshold, replacing a trace amount of CB with equivalent carbon nanofibers (CNFs) produces hybrid dispersions with higher electrical conductivity and comparable rheological behavior to pure CB dispersions. This hybrid dispersion is dominated by a cooperatively supporting network, which is wired by the flexible filamentous nanofibers so that it is able to recover the conductivity loss under flow conditions due to flow-induced breaking up of the conductive pathways of CB and presumably sustain a higher load of active materials. This finding suggests hybrid dispersions as a promising precursor in the formulation of electrode suspensions for aqueous semi-solid redox flow cells. 2018 The Royal Society of Chemistry. M. Youssry would like thank Cabot Corporation, USA and 3M, France for providing, respectively, the carbon black and lithium salt, and Dr Nasr Bensalah for helping in conducting the impedance spectra. We would like to thank the staff of Central Lab Unit at Qatar University for performing SEM and Raman spectra. This work was partially supported by an internal grant (QUST-CAS-SPR-2017-6) from Qatar University. Scopus

In an attempt to introduce a novel approach to formulate carbon black (ketjen black) suspension with enhanced colloidal stability, improved flowability, and higher conductivity, ketjen black was dispersed in microemulsion systems composed of a non-ionic surfactant (Triton X100), decanol, and water. Rheo-electric and rheo-microscopy proved to be very powerful techniques that are able to elucidate the microstructure evolution with the composition and under shear flow. Interestingly, the carbon black slurries at low decanol/water ratio are weak gels (flowable) with higher electrical conductivity than those at higher ratio, which shows strong-gel viscoelastic response. In addition, the slurries show recoverable electrical behavior under shear flow in tandem with the viscosity trend. It is likely that the oil-in-water microemulsion enhances slurries' stability without affecting the percolating network of carbon black. On the other hand, the oil-in-water analogous and bilayer structure of the lamellar phase makes the slurries less conductive as a consequence of losing the network percolation. Scopus

Polymeric micelles are potentially efficient in encapsulating and performing the controlled release of various hydrophobic drug molecules. Understanding the fundamental physicochemical properties behind drug–polymer systems in terms of interaction strength and compatibility, drug partition coefficient (preferential solubilization), micelle size, morphology, etc., encourages the formulation of polymeric nanocarriers with enhanced drug encapsulating capacity, prolonged circulation time, and stability in the human body. In this review, we systematically address some open issues which are considered to be obstacles inhibiting the commercial availability of polymer-based therapeutics, such as the enhancement of encapsulation capacity by finding better drug–polymer compatibility, the drug-release kinetics and mechanisms under chemical and mechanical conditions simulating to physiological conditions, and the role of preparation methods and solvents on the overall performance of micelles.

In general, microrheology is carried out using active or passive particle-tracking techniques. In the present paper, a novel technique based on the out-of-plane bending vibrations of a microcantilever beam immersed into a liquid is proposed for microrheological property measurement. We propose to analytically link the damped beam motion with the rheological properties of the fluid in order to establish a dynamic rheogram which spans at least one decade of the kiloHertz frequency domain. The latest improvements in terms of both analytical modeling and experimental set-up are detailed, along with a complete explanation of the calculation method. Four rheograms of Newtonian and non-Newtonian liquids obtained from the frequency response of three immersed cantilevers of different geometries are presented.

The nonaqueous suspensions of carbon nanofibers (CNFs) in 1 M lithium bis(trifluoromethanesulfonaimide) in propylene carbonate electrolyte reveal unique structural evolution and shear-induced transition due to the high aspect ratio. The rheo-electrical behavior elucidates a microstructural transition from entangled-to-aggregated networks above a distinct percolation threshold. Under shear flow, both networks show a three-regime flow curve and an inverted-bell-like conductivity curve as a consequence of shear-induced alignment (entangled network) and shear-induced breaking up (aggregated network). The different particle morphology of carbon nanofibers (anisometric) and carbon black (CB; isometric) causes different aggregation mechanisms (aggregate vs. particulate) and then varied microstructure for their suspensions in the same electrolyte. This fact explains the higher rigidity and lower electric conductivity of CNFs than CB suspensions. Interestingly, the suspension of hybrid carbons at the optimum mixing ratio merges the advantages of both carbons to operate efficiently as precursors in the formulation of electrodes for energy storage systems.

Vibrating microcantilevers are used to measure the density and the viscosity of surrounding fluids. The classical procedure involves experimental acquisition of the deflection spectrum of the beam, but a systematic calibration step is mandatory for obtaining viscosity and density. In the present study, a method is proposed to facilitate these measurements for Newtonian fluids with only one calibration step in air during the cantilever lifetime. Our approach relies on a complete theoretical analysis allowing to approximate semi-analytically the deflection spectrum with a second-order transfer function and to determine an analytical relationship between viscosity, density and the parameters of the transfer function. Fluid parameter determination results are shown for validation and discussed.

We investigate the consequence of decreasing the temperature on the rheological behavior of the cylindrical and branched micelles of the ternary system of DDAB (dodecyldimethylammonium bromide)/STDC (sodium taurodeoxycholate)/water system. An isotropic cylindrical micelle-to-hexagonal liquid crystalline phase is optically (as a birefringence) and rheologically (gel like) detected on the STDC rich part at 6°C. On the other hand, branched micellar solution does not show any birefringence upon decreasing the temperature; however, it mainly exhibits disordered-ordered transition under shear. Such transition is more pronounced as the DDAB concentration increases as a consequence of the decrease in the curvature, and hence a sponge phase formation at low temperature.

In Youssry et al.1, the incorrect image was provided for Fig. 5. The correct figure is below.

Vibrating microcantilevers can be used to measure density and viscosity of surrounding fluids. The classical procedure involves experimental acquisition of the deflection spectrum of the beam, but a systematic calibration step is mandatory for obtaining viscosity and density. In the present study, a method is proposed to facilitate these measurements for Newtonian fluids with only one calibration step in the cantilever lifetime. Our approach is based on approximating the deflection spectrum with a secondorder transfer function and determining a simple analytical relationship between viscosity, density and the parameters of the transfer function. Fluid parameters determination results are shown for validation and discussed.

Diacylglycerol-amino acid conjugates constitute a novel class of biocompatible surfactants being of great interest both from academic and industrial viewpoints. In this paper, the aqueous phase behaviour of 1,2-di-lauroyl- rac -glycero-3-( N α -acetyl- l -arginine) (indicated as 1212RAc) is investigated by a number of experimental approaches. The phase diagram is dominated by three monophasic regions; an isotropic solution, and two lamellar phases separated by a birefringent biphasic region. At very low concentrations ( C Iso ) is mainly composed of monodispersed vesicles ( R h ≈ 300 nm). Within the concentration interval 2 wt.% C Lam 1 ) occurs which is thermodynamically stable over a wide T -interval. This turbid phase (slightly birefringent under shaking) seems to consist of close-packed vesicles exhibiting flow properties varying with the composition and the temperature. Above 42 wt.% 1212RAc, a soft birefringent lamellar phase ( Lam 2 ) exhibiting all properties of smectic lamellar structures is observed. The analysis of phase behaviour of 1212RAc/ 2 H 2 O system is completed by a physicochemical study on the properties of some selected mixtures in the monophasic regions. In this part of the paper, we characterize the thermotropic phase transitions, viscoelasticity and shear flow of Lam 1 , as well as the swelling properties and the water organization in Lam 2 phase.

The mixed didodecyldimethylammonium bromide (DDAB)-sodium taurodeoxycholate (STDC)-(2)H(2)O catanionic system forms a large isotropic (L(1)) phase at 25 degrees C. The evolution of microstructure along different dilution lines has been followed by means of rheology and NMR diffusometry. In general, the L(1) phase is characterised by a weak viscoelasticity and Newtonian response. In the STDC-rich regime (W(s)=[DDAB]/[STDC]=0.2), 5 wt% is an overlapping concentration at which the discrete-to-rodlike micellar transition occurs as indicated from the total surfactant concentration (C(s)) dependency of both zero-shear viscosity (eta(0) approximately C(s)(3.7)) and surfactant self-diffusion (D(s) approximately C(s)(-3.0)). As the surfactant molar ratio (W(s)1) increases, i.e., DDAB concentration increases, and at constant C(s), eta(0) decreases and D(s) increases, indicating the formation of a multiconnected micellar network.

Cryopreservation of human gametes, embryos and blastocysts has become an integral part of assisted reproduction. This approach may have several advantages for infertile patients. It provides an opportunity to limit the numbers of embryos transferred while supernumerary embryos will be used in subsequent treatment cycles, thereby increasing the cumulative pregnancy rate. Furthermore, the potential risk of hyperstimulation syndrome can be reduced. In addition, storage of embryos from a cycle allows the patient to space the timing of sibling pregnancies and improve their potential of achieving a pregnancy at an advanced maternal age. Therefore, a reliable procedure for the cryopreservation of supernumerary embryos is needed. Since the early 1980s, two common techniques have been used in cryopreservation: the conventional slow cooling method and the more recent rapid procedure, known as vitrification. The latter needs a much higher concentration of cryoprotectants and faster cooling rates. Vitrification is qu...

We have investigated linear rheological properties and the structure–flow relationship of the swollen (Lam 1 ) and collapsed (Lam 2 ) lamellar phases, formed on didodecyldimethylammonium bromide (DDAB)/lecithin/water ternary system at 25 °C. Both lamellar phases behaved like Bingham fluids and showed remarkable yield stresses. At rest the Lam 1 phase, which is characterized by densely packed vesicles whose sizes increase as the water content decreases in accordance to evolution of 2 H NMR spectral profiles of D 2 O, resulted in a strong elastic gel-like response. On the other hand, the Lam 2 phase, formed at high surfactant concentrations, showed a weak-gel viscoelasticity and 2 H NMR spectral patterns which are typical of planar bilayered structures. The increase of the quadrupole splitting as the water content decreases was assumed as a strong evidence of size increasing of the lamellar domains. We have demonstrated that by using dynamic rheology and the derived relaxation time spectra, along with 2 H NMR spectra of D 2 O, it is possible to differentiate between equilibrium lamellar structures occurring in a broad interval of total surfactant concentration. In addition, a shear-thickening regime, observed at intermediate shear-rate values, highlighted the onset of out-equilibrium lamellar structures which were present both on Lam 1 and Lam 2 phases.

Sperm DNA contributes half the offspring's genomic material and abnormal DNA can lead to derangements in the reproductive process. Normal sperm genetic material is required for successful fertilization, as well as for further embryo and fetal development that will result in a healthy child. Thus, the damage to sperm DNA is critical in assisted reproductive techniques which are increasingly used to treat infertile couples. There has been improving data about the effects of human sperm DNA damage or fragmentation. As well, increasing knowledge concerning the effects of DNA damage on embryo and fetal development has been attained. This review aims to summarize the present knowledge on the impact of human sperm cell DNA damage on male infertility and outcome in the context of safety.

In an attempt to optimize a suspension electrode for redox flow batteries, this work demonstrates the effect of solid content and additive material on the electrical and rheological behavior of an anolyte made up of lithium titanium oxide (Li4Ti5O12 (LTO), as active material), carbon black (Ketjen black (KB), as a conductive material) suspended in organic medium (1 M lithium bis(trifluoromethane)sulfonimide; LiTFSI in propylene carbonate). The rheo-electrical properties of the anolyte are very sensitive to the Li4Ti5O12 content. The 20 wt% LTO is the maximum loading the percolated KB network can sustain without significant loss of the electronic conductivity and flowability of the electrode. Interestingly, this critical concentration increases to 25 wt% by addition of trace amount of conductive carbon nanofibers (CNFs) which electronically wire the conductive pathways and even reduce viscosity of the suspension electrode. Under shear flow, the suspension electrodes show three-regime flow curves with intermediate shear-thickening regions in accordance with minima in the conductivity. These minima are sharper at higher KB content, but nearly disappear in suspension electrodes with CNFs additive implying its role in wiring the ruptured conductive pathways under flow.

Redox-flow batteries (RFBs) store electrochemical energy in two fluids contained in external tanks, so called anolyte and catholyte which are pumped and flow through an electrochemical reactor in which electro-active species are oxidized and reduced. This feature provides to RFBs a unique ability in decoupling the energy and the power, therefore providing a significant design freedom for stationary applications. An interesting concept to deal with the energy density of RFBs, proposed by Chiang et al. [1], consists to use solid electro-active particles suspended in a Li+ containing electrolyte. The interest of such Semi-Solid Flow Cell (SSFC) system has recently been demonstrated with energy density ten times higher compared to classical RFBs [2,3]. Subsequently, Gogotsi et al. proposed an analogous to supercapacitors, the so called electrochemical flow capacitor (EFC) in which the energy is stored in the electric double layer of charged carbon particles [4]. A flowable carbon-electrolyte mixture is employed as the active material for capacitive energy storage, and is handled in a similar fashion to flow as for semi-solid batteries. Performance of SSFC (and EFC) system strongly depends on the flow ability of the anolyte and catholyte suspensions combined with their electronic conductivity which is governed by the extent of the carbon black percolation. In this regards, we have recently investigated the rheological and electrical behaviours of two carbon blacks [5], namely, Ketjen black EC-300 (KB) and C-NERGY Super C45, which differ by their primary particle size, and blends of Li4Ti5O12 (LTO) and KB, suspended in an organic electrolyte, a solution of 1M of Lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) in propylene carbonate (PC). The electrochemical performance of the LTO/KB/PC-LiTFSI suspension was investigated vs. lithium metal electrode as function of the cycling rate in static mode (i.e. no flow) and using a home-made cell that allows studying the influence of the thickness of the suspension [6]. Recently, we demonstrated the very beneficial influence of the addition of a nonionic surfactant in the composition of the LTO/KB/PC-LiTFSI anolyte suspension. All practical properties are improved with respect to semi-solid redox flow application. As a matter of fact, the viscosity is decreased, the electronic conductivity is increased and is less affected by the shear flow, and the electrochemical performance is increased. Moreover, a much better stability with time of the suspension is obtained, which means the preservation of its performance with time. References [1] Y.-M. Chiang, W. C. Carter, B. Ho, and M. Duduta, WO2009151639A1, 2009. [2] M. Duduta, B. Ho, V. C. Wood, P. Limthongkul, V. E. Brunini, W. C. Carter, Y.-M. Chiang, Adv. Mater., 1, 511 (2011). [3] S. Hamelet, T. Tzedakis, J.-B. Leriche, S. Sailler, D. Larcher, P.-L. Taberna, P. Simon and J.-M. Tarascon, J. Electrochem. Soc., 159, A1360 (2012). [4] V. Presser, C. R. Dennison, J. Campos, K. W. Knehr, E. C. Kumbur, and Y. Gogotsi, Adv. Energy Mater., 2, 895 (2012). [5] M. Youssry, L. Madec, P. Soudan, M. Cerbelaud, D. Guyomard and B. Lestriez, Phys. Chem. Chem. Phys., 15, 14476 (2013). [6] L. Madec, M. Youssry, M. Cerbelaud, P. Soudan, D. Guyomard and B. Lestriez, J. Electrochem. Soc.,161, A693 (2014) Figure 1. (a) Variation of the (a) conductivity Σ and of the (b) viscosity η with the shear rate for 20LTO3KB composite suspensions at 0 and 5 wt% TX (at 25 °C). (c) Comparison of the typical galvanostatic discharge/charge profiles of 20LTO3KB anolyte suspensions without and with 5 wt% of the non-ionic surfactant (TX) obtained in static mode (no flow) at C/25 rate for 0.75 mm thickness. The arrows denote the signature of an heterogeneous electronic wiring of the LTO particles in the 0TX anolyte.

Background: Polycystic ovary syndrome (PCOS) is the commonest cause of chronic hyperandrogenic anovulation. Insulin resistance and compensatory hyperinsulinemia are keys of the pathogenesis of PCOS. It is also considered as a metabolic disorder. Since the components of metabolic syndrome (MBS) namely obesity, glucose intolerance, dyslipidemia, and hypertension are the common features of this syndrome. The association between MBS and PCOS can be explained by different theories as insulin resistance, obesity, and related adipose tissue factors (adipocytokines) independent of insulin resistance are the main pathogenic contributors to both disorders.Methods: A total of 143 women with PCOS were recruited as study subjects. All participants were subjected to anthropometric measurements, clinical assessment, and biochemical tests [fasting glucose, fasting insulin, and homeostatic model assessment-insulin resistance (HOMA-IR)]. Hormonal profile particularly leptin and homocysteine levels were also evaluated.Results: 25 patients (17.4%) out of 143 women with PCOS met the criteria for MBS. Patients with MBS had significantly higher body mass index, blood pressure, HOMA-IR, leptin, and homocysteine levels compared to PCOS only patients. When HOMA-IR cut off was ≥4.3 sensitivity and specificity were 90%, 88.6%, but when leptin level was ≥34.5 the corresponding statistics were 79.6%, 75.5%.Conclusions: Serum leptin, homocysteine, HOMA-IR as well as other biochemical markers are significantly higher in women with PCOS and MBS compared to PCOS only women. PCOS is associated with various factors like insulin resistance, obesity, and dyslipidemia. Consequently, adipocytokines and HOMA-IR play important role in the prediction of MBS in patients with PCOS.

International audience; We report on the rheological and electrical properties of non-aqueous carbon black (CB) suspensions at equilibrium and under steady shear flow. The smaller the primary particle size of carbon black is, the higher the magnitude of rheological parameters and the conductivity are. The electrical percolation threshold ranges seem to coincide with the strong gel rather than the weak gel rheological threshold ones. The simultaneous measurements of electrical properties under shear flow reveal the well-known breaking-and-reforming mechanism that characterises such complex fluids. The small shear rate breaks up the network into smaller agglomerates, which in turn transform into anisometric eroded ones at very high shear rates, recovering the network conductivity. The type of carbon black, its concentration range and the flow rate range are now precisely identified for optimizing the performance of a redox flow battery. A preliminary electrochemical study for a composite anolyte (CB/Li4Ti5O12) at different charge-discharge rates and thicknesses is shown.

Silicon microcantilevers can be used to measure the rheological properties of complex fluids. In this paper, two different methods will be presented. In the first method, the microcantilever is used to measure the hydrodynamic force exerted by a confined fluid on a sphere that is attached to the microcantilever. In the second method, the measurement of the microcantilever's dynamic spectrum is used to extract the hydrodynamic force exerted by the surrounding fluid on the microcantilever. The originality of the proposed methods lies in the fact that not only may the viscosity of the fluid be measured, but also the fluid's viscoelasticity, that is, both viscous and elastic properties, which are key parameters in the case of complex fluids. In both methods, the use of analytical equations permits the fluid's complex shear modulus to be extracted and expressed as a function of shear stress and/or frequency.

International audience; Due to the need for a microrheometer monitoring the high‐frequency viscoelasticityof soft matter in situ, we describe a cantilever‐based microrheometer to achieve thispurpose. The elastic and viscous moduli of complex fluids can be measured with anacceptable accuracy over a high frequency bandwidth of 1‐100 kHz. Some preliminary dataon small samples (~10‐100 μL) of simple Newtonian and viscoelastic polymer andsurfactant solutions showed the ability to measure the dynamic moduli in the range of 0.01‐10 kPa. This approach will provide a new way to characterize in situ, dynamicmicrorheology of minute and trace materials and will advance the field of biorheology,microfluidics, and polymer processing.

The influence of shear flow on bilayer structures (vesicle and planar lamellar phases, Lα), formed in DDAB/lecithin ternary systems, is studied by means of conventional rheology, Rheo NMR, and optical microscopy. The vesicles in the diluted (Lam1) phase are polydisperse multilamellae which turn into smaller monodisperse vesicles under shear. The concentrated (Lam2) phase is formed by non-oriented lamellae that do not surprisingly exhibit any pronounced shear-induced alignment prior to the transition into giant multilamellar vesicles. The biphasic region (Lam1 + Lam2) shows a mosaic texture with a powder pattern indicating the prevalence of lamellae that transform into onions under shear.

The dynamical characteristics and the thermal analysis of water absorbed in filler-free Nafion and in silica or zirconia phosphate Nafion composites, between 20 and -50 degrees C, were investigated by NMR and DSC techniques. Self-diffusion coefficients and longitudinal NMR relaxation times (T(1)) put in evidence a fraction of water freezing at subzero temperatures. The complementary water fraction remains in the liquid state at least down to -50 degrees C. The freezing point (T(f)) depends on the initial water uptake of the electrolyte membrane and, for similar uptake values, water mobility is favorite in composites systems respect to the filler-free Nafion. By DSC thermograms the hydration water molecules number per sulfonic group in the filler-free Nafion was estimated, obtaining 8 molecules/SO(3)(-) group. In the Nafion/Zr(HPO(4))(2) composite, instead, the number of hydration water is about 20 molecules/ionic group, because of the acid nature of the zirconia particles. Below T(f), the presence of this nonfreezable water fraction allows proton transport, and therefore ensures ionic conductivity also at subzero temperatures.

Here we report on a study dealing with a self-assembling ethylene oxide-propylene oxide-ethylene oxide triblock copolymer (Pluronic L64) and an anionic surfactant, sodium dodecyl sulfate (SDS), that in water at 25 degrees C form an interesting micellar region (L-phase). We have investigated the sequence of micelle structures in this L-phase across a wide interval of copolymer concentrations using phase diagram determination, steady shear, and NMR self-diffusion (pulsed gradient spin-echo, PGSE) experiments. In solutions which have been prepared at moderately low copolymer concentrations (ca. 20wt.% L64) we report on a transition from discrete micelles to bicontinuous aggregates on the addition of SDS. This change was mainly inferred from self-diffusion coefficient patterns (i.e., the variation of copolymers and surfactant diffusivity vs. SDS content). At midrange and at higher polymer concentrations (i.e., in the interval from 50 to 80wt.% L64) the L-phase occurred with a bicontinuous structure which was not modified by the progressive addition of SDS. Such a bicontinuous structure was identified by the comparison of self-diffusion coefficients of both cosolutes and the bulk viscosity (i.e., the behavior of zero-shear viscosity vs. SDS).

The thermal behavior of unsonicated dispersions of a double-chained surfactant, Dioctadecyldimethylammonium bromide (DODAB), has been studied over a wide concentration range using DSC and dynamic rheology. All dispersions are characterized by the pre- and main transition peaks at 35 degrees C and 43 degrees C, respectively. But, only above 10 mM DODAB, a third endotherm at 52 degrees C appears which may correspond to the (ULVs+Lalpha fragments)--MLVs transition. The thermal-induced MLV's size is proportionally dependent on the concentration. In addition, and in agreement with DSC data, dynamic rheology has proven to be an indirect way to elucidate the structural transitions in these DODAB vesicular dispersions.

In this paper, some new physicochemical properties of sodium taurodeoxycholate (STDC)-water system are carefully investigated using shear rheology and NMR diffusometry. Of clear interest to us was the study of structure and/or morphology of the isotropic liquid and the hexagonal phase.We observed that the isotropic liquid phase (C30 wt% STDC) consists of a micellar solution (L1) and presents a sharp structural transition from spherical micelles to an entangled network upon increasing the concentration. Below 10 degrees C, the L1 phase transforms slowly into a firm, gel phase (V) which results stable in the composition interval 15C30 wt%. The linear viscoelasticity of this phase is interpreted by means of the cooperative-flow theory.The liquid crystalline phase (36C65 wt% STDC) is unequivocally characterized as having a direct hexagonal structure (H1). Specifically, the hexagonal mixture with 45 wt% STDC presents a low thermal stability (T35 degrees C) and slow kinetics at the liquid-hexagonal transition (5 hours). The linear viscoelasticity of this phase is interpreted by means of the generalized Maxwell model. All these findings are confirmed by some additional measurements performed on a lyotropic mixture of hexaethylene glycol monododecyl ether (C12E6), a nonionic surfactant forming a direct hexagonal phase in a similar interval of compositions and temperatures of STDC.

Objective To present a live birth after freezing and thawing of biopsied oocytes. Design Case report. Setting Artificial reproduction unit of a university hospital. Patient(s) A primary infertile couple with asthenoteratozoospermia and repeated failures of intracytoplasmic sperm injection (ICSI). Intervention(s) Screening of aneuploidy during the fourth ICSI cycle with polar body biopsy (PB) for repeated failures of artificial reproductive techniques and a transfer of a cryopreserved day 2 embryo derived from cryopreserved zygotes with slow-rate freezing after PB. Main Outcomes Measure(s) Live birth, viability, and survival. Result(s) A successful pregnancy and a live birth were presented after a transfer of day 2 embryos derived from oocytes that underwent PB and subsequent cryopreservation. Conclusion(s) Pregnancy can be obtained subsequent to cryopreservation and thawing after PB.

Cryopreservation of human gametes and embryos has become an essential part of assisted reproduction. Successful cryopreservation of human blastocysts is increasingly relevant as extended in-vitro culture of human embryos becomes more common, permitting routine use of blastocyst transfer in IVF programmes. This reduces the number of embryos transferred, thereby reducing multiple pregnancies and maximizing cumulative pregnancy rates per oocyte retrieval. The superiority of blastocyst freezing over earlier stage freezing in terms of implantation per thawed embryo transferred improves overall expectations for the cryopreservation programme. Therefore, a reliable procedure for the cryopreservation of blastocysts is needed because, after transfer, only a small number of supernumerary blastocysts are likely to be available for cryopreservation. Since the early 1980s, two common techniques have been used in cryopreservation: the conventional slow cooling method and the more recent rapid procedure known as vitrification. Vitrification has become an attractive alternative to slow freezing, since it appears to result in significantly higher survival and pregnancy rates. The aim of this review is to focus on the cryopreservation of human blastocysts using slow and rapid protocols and to assess the impact of the crypreservation protocol used on the survival, implantation and pregnancy rates.