The Efficacy of Intravenous Versus Topical Use of Tranexamic Acid in Reducing Blood Loss after Primary Total Knee Arthroplasty: A Randomized Clinical Trial.

BACKGROUND: Blood loss during and immediately after total knee arthroplasty (TKA) is among the most challenging concerns. It has been demonstrated that Tranexamic acid (TXA) can help to reduce perioperative blood loss. TXA can be used as an oral, topical or intravenous injection. Many studies evaluated the effectiveness of each route of administration but few works on a comparison between them. The current study aimed to compare the effectiveness of intravenous injection versus topical use of TXA in reducing perioperative blood loss after primary total knee arthroplasty. METHODS: Eighty-five patients who were a candidate for total knee arthroplasty were randomized into two groups: one group received Intravenous injection of 15 mg/kg TXA, 10 min before tourniquet inflation while the other group received 1 g diluted TXA during wound closure. The postoperative blood loss was estimated by measuring the whole drain output and also hemoglobin (HB) drops. Both groups compared based on the need for allogenic blood transfusion and also thromboembolic events. RESULTS: Patients who received topical TXA had a higher total drain output (p <0.0001) compared to intravenous injection. The hemoglobin drop also was more in the topical group although it was marginally significant (p =0.05). CONCLUSION: Intravenous injection of TXA is more effective in reducing postoperative blood loss after primary TKA compared to topical administration.

Generalized models for advancing and receding contact angles of fakir droplets on pillared and pored surfaces.

Understanding how surface properties determine the mobility of a fakir droplet on patterned surfaces, which is typically characterized by advancing and receding contact angles, is important in the design of superhydrophobic surfaces for tailored applications. However, most analytical models of the contact angles are limited to a specific motion direction and surface type, e.g., receding on a pillared surface. Although it was suggested that the contact angles should be determined by the local configuration and dynamics of the droplet boundary, their link remains vague due to the lack of detailed visualizations. In this study, the contact line dynamics of a fakir droplet in both advancing and receding motions on not only micropillared but also micropored surfaces are visualized in reflection interference contrast microscopy along with the contact angle measurement. Based on the energy change induced by the displacement of a contact line and the deformation of a liquid-gas interface in between contact lines, theoretical models of the contact angles to encompass the two different motion directions and surface types are formulated. Moreover, further generalized models are established to serve as effective analytical models to predict the contact angles only based on the given structure dimensions and the inherent surface hydrophobicity.

Depinning force of a receding droplet on pillared superhydrophobic surfaces: Analytical models.

It was experimentally shown that a depinning force of a receding droplet on a micropillared superhydrophobic surface has an apparently linear correlation with the maximal three-phase contact line attainable along an actual droplet boundary. However, the experimental observation has not yet been supported by any theoretical basis or analysis. This study establishes an analytical model that theoretically supports the experimental observation on the basis of the dynamics of a contact line. The depinning force of a receding droplet was experimentally measured in evaporation on micropillared superhydrophobic surfaces with varying structure pitches but a fixed size. The analytical model was established by considering the energy dissipated by the displacement of a microscopic contact line on pillar tops and the energy consumed for the distortion of a liquid-gas interface between pillar tops. The model shows that the depinning force can theoretically be estimated by the physical dimensions of pillars and the intrinsic hydrophobicity of the surface, showing excellent agreement with the experimental results. Especially, the model indicates that the depinning force is fundamentally determined and practically controllable by the normalized maximal contact line at the droplet boundary, which can effectively be represented as the ratio of the pillar top perimeter to pitch.

Anti-Icing or Deicing: Icephobicities of Superhydrophobic Surfaces with Hierarchical Structures.

Superhydrophobic surfaces have gained tremendous attention for icephobic properties, including anti-icing and deicing. The former is about how much a surface can delay the ice formation, whereas the latter is about how easy the surface can let the ice go off after freezing. In this study, superhydrophobic surfaces with different surface roughnesses and wettabilities were tested for both anti-icing and deicing purposes to investigate their correlation in association with the different surface properties. Anti-icing test was conducted by utilizing an icing wind tunnel to see how much ice gets accumulated on the surfaces in a dynamic condition (i.e., impacting supercooled water droplets by forced wind). For the deicing test, sessile droplets were frozen on the surfaces in a static condition (i.e., no wind) and then the shear adhesion forces were measured to disconnect the frozen ices off from the surfaces. The experimental results show that higher anti-icing efficacy does not necessarily mean higher deicing efficacy because of the different icing mechanisms. Although a superhydrophobic surface with a lower depinning force (or contact angle hysteresis) delays the ice accumulation in a dynamic condition more effectively, the same surface can require higher shear adhesion force for ice grown in a static condition where condensation and wetting state of a droplet are the key factors.

Bubble Movement on Inclined Hydrophobic Surfaces.

The movement of a single air bubble on an inclined hydrophobic surface submerged in water, including both the upward- and downward-facing sides of the surface, was investigated. A planar Teflon sheet with an apparent contact angle of a sessile water droplet of 106° was used as a hydrophobic surface. The volume of a bubble and the inclination angle of a Teflon sheet varied in the ranges 5-40 µL and 0-45°, respectively. The effects of the bubble volume on the adhesion and dynamics of the bubble were studied experimentally on the facing-up and facing-down surfaces of the submerged hydrophobic Teflon sheet, respectively, and compared. The result shows that the sliding angle has an inverse relationship with the bubble volume for both the upward- and downward-facing surfaces. However, at the same given volume, the bubble on the downward-facing surface spreads over a larger area of the hydrophobic surface than the upward-facing surface due to the greater hydrostatic pressure acting on the bubble on the downward-facing surface. This makes the lateral adhesion force of the bubble greater and requires a larger inclination angle to result in sliding.

Combined optical micromanipulation and interferometric topography (COMMIT).

Optical tweezers have emerged as a prominent light-based tool for pico-Newton (pN) force microscopy in mechanobiological studies. However, the efficacy of optical tweezers are limited in applications where concurrent metrology of the nano-sized structures under interrogation is essential to the quantitative analysis of its mechanical properties and various mechanotransduction events. We have developed an all-optical platform delivering pN force resolution in parallel with nano-scale structural imaging of the biological sample by combining optical tweezers with interferometric quantitative phase microscopy. These capabilities allow real-time micromanipulation and label-free measurement of sample's nanostructures and nanomechanical responses, opening avenues to a wide range of new research possibilities and applications in biology.

Experimental investigation of ionic liquid pretreatment of sugarcane bagasse with 1,3-dimethylimadazolium dimethyl phosphate.

In this study, an imidazolium-based ionic liquid (IL), 1,3-dimethylimidazolium dimethyl phosphate ([Mmim][DMP]), was applied for pretreating sugarcane bagasse to produce bioethanol. The main goal of this study was to investigate the feasibility of bagasse pretreatment with this IL, and to verify the effect of different operational parameters on the pretreatment process. Results indicated that temperature and duration of IL-pretreatment have optimum values. Within the range investigated, a maximum fermentable sugar conversion of 70.38% was achieved with this IL at 120°C and 120min. The corresponding value was 28.65% for the untreated biomass. The main cause for the observed enhancement in enzymatic hydrolysis was the reduction of cellulose crystallinity in the IL-pretreated biomass, as compared to the untreated sample, because it resulted in higher accessibility of the enzymes to the biomass after pretreatment. Moreover, the results indicated that aqueous [Mmim][DMP] mixtures are not as effective for pretreatment as the pure IL.

Comparative study of methods to calibrate the stiffness of a single-beam gradient-force optical tweezers over various laser trapping powers.

Optical tweezers have become an important instrument in force measurements associated with various physical, biological, and biophysical phenomena. Quantitative use of optical tweezers relies on accurate calibration of the stiffness of the optical trap. Using the same optical tweezers platform operating at 1064 nm and beads with two different diameters, we present a comparative study of viscous drag force, equipartition theorem, Boltzmann statistics, and power spectral density (PSD) as methods in calibrating the stiffness of a single beam gradient force optical trap at trapping laser powers in the range of 0.05 to 1.38 W at the focal plane. The equipartition theorem and Boltzmann statistic methods demonstrate a linear stiffness with trapping laser powers up to 355 mW, when used in conjunction with video position sensing means. The PSD of a trapped particle's Brownian motion or measurements of the particle displacement against known viscous drag forces can be reliably used for stiffness calibration of an optical trap over a greater range of trapping laser powers. Viscous drag stiffness calibration method produces results relevant to applications where trapped particle undergoes large displacements, and at a given position sensing resolution, can be used for stiffness calibration at higher trapping laser powers than the PSD method.

Large-amplitude, reversible, pH-triggered wetting transitions enabled by layer-by-layer films.

We report on the use of layer-by-layer (LbL) hydrogels, composed of amphiphilic polymers that undergo reversible collapse-dissolution transition in solutions as a function of pH, to induce sharp, large-amplitude wetting transition at microstructured surfaces. Surface hydrogels were composed of poly(2-alkylacrylic acids) (PaAAs) of varied hydrophobicity, i.e., poly(methacrylic acid) (PMAA), poly(2-ethylacrylic acid) (PEAA), poly(2-n-propylacrylic acid) (PPAA) and poly(2-n-butylacrylic acid) (PBAA). When deposited at a micropillar-patterned silicon substrate, hydrophilic PMAA LbL hydrogels supported complete surface wetting (contact angle, CA, of 0°), whereas PEAA, PPAA, and PBAA ultrathin coatings supported large-amplitude wetting transitions, with CA changes from 110 to 125° at acidic to 0° at basic pH values, and the transition pH increasing from 6.2 to 8.4 with increased polyacid hydrophobicity. At acidic pHs, droplets showed a large hysteresis in CA (a "sticky droplet" behavior), and remained in the Wenzel state. The fact that CA changes for wetting-nonwetting transitions occurred at values close to physiologic pH makes these coatings promising for controlling flow and bioadhesion using external stimuli. Finally, we show that the surface wettability transitions can be used to detect positively charged analytes (such as gentamicin) in solution via large changes in CA associated with adsorption of analytes within the hydrogels.

Experimental study and neural network modeling of sugarcane bagasse pretreatment with H2SO4 and O3 for cellulosic material conversion to sugar.

In this study, pretreatment of sugarcane bagasse and subsequent enzymatic hydrolysis is investigated using two categories of pretreatment methods: dilute acid (DA) pretreatment and combined DA-ozonolysis (DAO) method. Both methods are accomplished at different solid ratios, sulfuric acid concentrations, autoclave residence times, bagasse moisture content, and ozonolysis time. The results show that the DAO pretreatment can significantly increase the production of glucose compared to DA method. Applying k-fold cross validation method, two optimal artificial neural networks (ANNs) are trained for estimations of glucose concentrations for DA and DAO pretreatment methods. Comparing the modeling results with experimental data indicates that the proposed ANNs have good estimation abilities.

Amyloid histology stain for rapid bacterial endospore imaging.

Bacterial endospores are some of the most resilient forms of life known to us, with their persistent survival capability resulting from a complex and effective structural organization. The outer membrane of endospores is surrounded by the densely packed endospore coat and exosporium, containing amyloid or amyloid-like proteins. In fact, it is the impenetrable composition of the endospore coat and the exosporium that makes staining methodologies for endospore detection complex and challenging. Therefore, a plausible strategy for facile and expedient staining would be to target components of the protective surface layers of the endospores. Instead of targeting endogenous markers encapsulated in the spores, here we demonstrated staining of these dormant life entities that targets the amyloid domains, i.e., the very surface components that make the coats of these species impenetrable. Using an amyloid staining dye, thioflavin T (ThT), we examined this strategy. A short incubation of bacillus endospore suspensions with ThT, under ambient conditions, resulted in (i) an enhancement of the fluorescence of ThT and (ii) the accumulation of ThT in the endospores, affording fluorescence images with excellent contrast ratios. Fluorescence images revealed that ThT tends to accumulate in the surface regions of the endospores. The observed fluorescence enhancement and dye accumulation, coupled with the sensitivity of emission techniques, provide an effective and rapid means of staining endospores without the inconvenience of pre- or posttreatment of samples.