•Liposomes composed of neutral lipids exhibit non-zero zeta potentials.•Zeta potentials of liposomes in water were different from those in ionic medium.•The sign of the zeta potential varies with the ...kind of lipid, medium, phase state and lamellarity.•The orientation of the head group in the liposome is relevant in the sign of the zeta potential.
The purpose of the work is to compare the influence of the multilamellarity, phase state, lipid head groups and ionic media on the origin of the surface potential of lipid membranes.
With this aim, we present a new analysis of the zeta potential of multilamellar and unilamellar vesicles composed by phosphatidylcholines (PC) and phosphatidylethanolamines (PE) dispersed in water and ionic solutions of polarizable anions, at temperatures below and above the phase transition.
In general, the adsorption of anions seems to explain the origin of the zeta potential in vesicles only above the transition temperature (Tc). In this case, the sign of the surface potential is ascribed to a partial orientation of head group moiety toward the aqueous phase. This is noticeable in PC head groups but not in PEs, due to the strong lateral interaction between PO and NH group in PE.
In the past few years, minimally invasive oesophagectomy has become an increasingly popular approach for oesophagectomy showing advantages in terms of fewer postoperative complications, shorter ...hospital stay and faster recovery. We present the case of a 60-year-old man with a lesion of the distal third of the oesophagus and solid pulmonary nodule who underwent McKeown subtotal oesophagectomy by laparoscopic and thoracoscopic approach in prone position with concomitant thoracoscopic pulmonary wedge resection. The postoperative course was smooth, and the patient was discharged on postoperative day 10. The procedure is feasible and safe, and combines better respiratory postoperative outcomes even when associated with other diagnostic or therapeutic lung procedures.
Minimally invasive oesophagectomy has become popular, but studies showed a higher rate of postoperative hiatus hernia compared with open oesophagectomy. Our video presents the laparoscopic ...biosynthetic mesh repair of a symptomatic giant hiatus hernia in a 71-year-old man who had undergone minimally invasive oesophagectomy one year earlier for distal adenocarcinoma of the oesophagus. The operative time was 120 minutes. The patient started oral intake on postoperative day one and was discharged on postoperative day three. Postoperative computed tomography at six months showed no signs of recurrence. In the setting of a symptomatic hiatus hernia post-minimally invasive oesophagectomy, we suggest an initial laparoscopic approach, because of its countless advantages.
Polymer nanocomposites synergistically combine the good thermal properties of the hosting polymer matrix with the high mechanical performance of the fillers, providing a new class of materials with ...superior properties.
The present study aims to evaluate in a multidisciplinary way the enhancement in mechanical and thermal-hygrometric properties of low and medium density nanophased polyurethane (PUR) foams with either randomly oriented or aligned nanofibers as compared to the neat ones.
To this aim, 1% weight of carbon nanofibers (CNFs) were homogeneously dispersed into polyol of PUR foam by an ultrasonic cavitation method. In parallel, a small amount of CNFs was functionalized in advance by a co-precipitation method so as to align them into the polymer matrix through an external low intensity magnetic field.
SEM analyses were used to compare the microstructure of the neat and nanophased samples.
Results have shown that the addition of carbon nanofibers in the foams products a closer structure with a more uniform size and shape. Moreover, functionalized CNFs play a significant role in regulating cells shape as well as strengthening cells walls.
Mechanical test results also demonstrated that CNFs increase both strength and stiffness of the samples. The alignment of carbon nanofibers within medium density nanophased foams determines the highest mechanical properties. However, the more noticeable improvement in samples performance occurred in low density nanophased foams.
Finally, carbon nanoparticles decrease the thermal conductivity and increase the resistance against water adsorption.
•Neat and nanophased PUR foams, with low and medium density.•Randomly oriented and aligned CNFs by a co-precipitation method.•CNFs determine a closer foams structure, increase strength and stiffness.•CNFs decrease thermal conductivity and increase water resistance.•More noticeable improvements in low-density foams.
Zeta potential with continuous cooling method—validated by DSC—for determining transition and pre-transition temperatures in lipid mixtures.
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•Temperature dependence of zeta potential ...(ZP) measurements is a high sensitivity method.•Allowed determining transition and pretransition temperatures in DPPC/DMPC mixtures.•Simple way to map the phase diagram.•We propose ZP as a screening method for transition temperatures in complex mixtures.
Temperature dependence of the zeta potential (ZP) is proposed as a tool to analyze the thermotropic behavior of unilamellar liposomes prepared from binary mixtures of phosphatidylcholines in the absence or presence of ions in aqueous suspensions. Since the lipid phase transition influences the surface potential of the liposome reflecting a sharp change in the ZP during the transition, it is proposed as a screening method for transition temperatures in complex systems, given its high sensitivity and small amount of sample required, that is, 70% less than that required in the use of conventional calorimeters. The sensitivity is also reflected in the pre-transition detection in the presence of ions. Plots of phase boundaries for these mixed-lipid vesicles were constructed by plotting the delimiting temperatures of both main phase transition and pre-transition vs. the lipid composition of the vesicle. Differential scanning calorimetry (DSC) studies, although subject to uncertainties in interpretation due to broad bands in lipid mixtures, allowed the validation of the temperature dependence of the ZP method for determining the phase transition and pre-transition temperatures. The system chosen was dipalmitoylphosphatidylcholine/dimyristoyl phosphatidylcholine (DMPC/DPPC), the most common combination in biological membranes. This work may be considered as a starting point for further research into more complex lipid mixtures with functional biological importance.
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We employ molecular dynamics simulations to study the hydration properties of Dipalmitoylphosphatidylcholine (DPPC) bilayers, both in the gel and the liquid crystalline states. We show that while ...the tight hydration centers (PO and CO moieties) are significantly hydrated in both phases, the gel-fluid transition involves significant changes at the second hydration shell, particularly at the buried region between the hydrocarbon tails. Thus, while almost no buried water population exists in the gel state below the carbonyls, this hydrophobic region becomes partially water accesible in the liquid crystalline state. We shall also show that such water molecules present a lower H-bond coordination as compared to the molecules at the primary hydration shell. This means that, while the latter are arranged in relatively compact nanoclusters (as already proposed), the buried water molecules tend to organize themselves in less compact structures, typically strings or branched strings, with a scarce population of isolated molecules. This behavior is similar to that observed in other hydration contexts, like water penetrating carbon nanotubes or model hydrophobic channels or pores, and reflects the reluctance of water to sacrifice HB coordination.
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A squintless slot-antenna array (2-D), built on a single substrate integrated waveguide (SIW) is shown. The effort needed for designing a suitable feeding network in SIW technology is justified in ...view of obtaining lightweight, low-profile, and low-cost antennas for many applications, including direct broadcast satellite. A proper definition of an "H"-shaped subarray, made of four slot-pairs, is used to improve the input matching over a wide band. This choice allows remarkable simplification of the fabrication process, as the slots are cut directly in one of the metallic planes forming the SIW.
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Many researches describe the embryonic developmental features in domestic animals; however, in farm animals, they are scarce. Most farm animal studies are related to assisted reproduction ...and embryos transfer techniques. But, morphological features and size measure to estimate the age gestation are rarely reported in literature. Thus, in this study, we described the developmental changes in the bubaline (Bubalus bubali) concepts from 21 to 60 days of gestation. Our results revealed that buffalo embryos similar morphological characteristics similar to other mammalian species. Also, similarities between bovine and bubaline persist; except on foetal stages when buffalos have a faster development than bovine. Therefore, buffalo's gestation period exhibits some varieties and accurate embryo age is more difficult. Yet, when we use a combination of the crown–rump, macroscopic analysis and alizarin red, it is possible to describe better the whole embryogenesis stages of the buffalo and which can contribute for future reproduction researches and applications in veterinary practice.
In this paper, we report a novel approach based on a lensless Synthetic Optical Holography (SOH) that is aimed to recover the complex scattered field from buried surfaces at different wavelengths ...with sub-nanometric spectral resolution, without affecting the phase retrieval in depth. The proposed technique is applied to characterize and image the field scattered from a rough embedded surface of a microfluidic channel. The real and imaginary part of the random complex field revealed the presence of 2D optical vortices at each location in which a phase singularity is located. A statistical study of optical vortices is presented and the high spectral resolution is exploited to study the behavior of topological charges with the frequency shift.
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This study had the aim of investigating the efficiency of timed artificial insemination (TAI) through the progesterone‐releasing intravaginal device (PRID), used in new condition and for the ...second and third times in Nelore cows. The effects of device reuse and body condition score (BCS) on the conception rate (CR) were evaluated in 1,122 multiparous Nelore cows (mean BCS of 2.7 ± 0.4), which were randomly distributed into three groups that received new (n = 330), once (n = 439) and twice used (n = 353) PRID. Among the 1,122 females that underwent TAI, 573 became pregnant, thus representing an overall CR of 51.06%. Cows with BCS between 2.75 and 4.0 had greater (p < .0001) CR (69.75%) than cows with BSC of 2.0–2.5 (32.98%). It was observed that the CR through using PRID was 60.00%, 51.71% and 41.93% for new, once and twice used PRID, respectively, with difference between all groups (p < .0001). Under tropical conditions, animals with BCS greater than 2.5 had a higher CR, and the CR decreased proportionally with the number of times that the PRID had been used.
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