Computed tomography-based gastric volumetry for morbid obesity to assess weight loss and fatty liver change.

BACKGROUND/PURPOSE: Laparoscopic sleeve gastrectomy (LSG) is an effective treatment for patients with morbid obesity, but the optimal gastric volume (GV) for resection remains unclear. Accordingly, we aimed to determine the optimal percentage of excised stomach that could engender significant weight loss and improve fatty liver. METHODS: This prospective study included 63 patients. Computed tomography (CT) scans were performed before and 1 year after LSG to evaluate the gastric lumen (GL) and GV. Specifically, the stomach was distended with effervescent powder, following water-contrast mixture (20:1) and assessed by three-dimensional reconstruction. The correlations of reduced gastric lumen/volume (RGL/RGV) with total body weight (BW) loss and liver-spleen density ratio (LSDR) changes were analyzed, and optimal RGL/RGV associated with significant BW and fatty liver changes were determined. RESULTS: We noted a positive correlation between the percentage of RGV/RGL (%RGV/%RGL) and percentage of total weight loss (%TWL; r = 0.359, p = 0.004 and r = 0.271, p = 0.032). Furthermore, a %RGL value of >78.2% and %RGV value of >75.3% were associated with more significant BW loss than did limited excision (both p < 0.01). On the other hand, LSDR values increased significantly after LSG, corresponding to the improvement of fatty liver disease at %RGL and %RGV values of >59.1% and >56.4% (both p < 0.01), respectively. CONCLUSION: %RGV and %RGL were determined to be factors affecting LSG outcomes. LSG engendered significantly more BW loss when %RGV was >75.3% and resulted in fatty liver disease improvement when %RGV was >56.4%.

Investigations of Shape Deformation Behaviors of the Ferromagnetic Ni-Mn-Ga Alloy/Porous Silicone Rubber Composite towards Actuator Applications.

Ferromagnetic shape memory alloys (FSMAs), which are potential candidates for future technologies (i.e., actuators in robots), have been paid much attention for their high work per volume and rapid response as external stimulation, such as a magnetic field, is imposed. Among all the FSMAs, the Ni-Mn-Ga-based alloys were considered promising materials due to their appropriate phase transformation temperatures and ferromagnetism. Nevertheless, their intrinsic embrittlement issue and sluggish twin motion due to the inhibition of grain boundaries restrict their practicability. This study took advantage of the single-crystal Ni-Mn-Ga cube/silicone rubber composite materials to solve the two aforementioned difficulties. The single-crystal Ni-Mn-Ga cube was prepared by using a high-temperature alloying procedure and a floating-zone (FZ) method, and the cubes were verified to be the near-{100}p Ni-Mn-Ga alloy. Various room temperature (RT) curing silicone rubbers were utilized as matrix materials. Furthermore, polystyrene foam particles (PFP) were used to provide pores, allowing a porous silicone rubber matrix. It was found that the elastic modulus of the silicone rubber was successfully reduced by introducing the PFP. Additionally, the magnetic field-induced martensite variant reorientation (MVR) was greatly enhanced by introducing a porous structure into the silicone rubber. The single-crystal Ni-Mn-Ga cube/porous silicone rubber composite materials are considered to be promising materials for applications in actuators.

Effects of 3d Transition Metal Substitutions on the Phase Stability and Mechanical Properties of Ti-5.5Al-11.8[Mo]eq Alloys.

The phase stability, mechanical properties, and functional properties of Ti-5.5Al-11.8[Mo]eq alloys are focused on in this study by substituting 3d transition metal elements (V, Cr, Co, and Ni) for Mo as ß-stabilizers to achieve similar ß phase stability and room temperature (RT) superelasticity. The ternary alloy systems with the equivalent chemical compositions of Ti-5.5Al-17.7V, Ti-5.5Al-9.5Cr, Ti-5.5Al-7.0Co, and Ti-5.5Al-9.5Ni (mass%) alloys were selected as the target materials based on the Mo equivalent formula, which has been applied for the Ti-5.5Al-11.8Mo alloy in the literature. The fundamental mechanical properties and functionalities of the selected alloys were examined. The ß phase was stabilized at RT in all alloys except for the Ti-Al-V alloy. Among all alloys, the Ti-Al-Ni alloy exhibited superelasticity in the cyclic loading-unloading tensile tests at RT. As a result, similar to the Ti-5.5Al-11.8Mo mother alloy, by utilizing the Mo equivalent formula to substitute 3d transition metal elements for Mo, a RT superelasticity was successfully imposed.

Framework of magnetostrain responsive Ni-Mn-Ga microparticles driving magnetic field induced out-of-plane actuation of laminate composite.

Ni-Mn-Ga single crystals (SC) exhibiting a giant magnetic field induced strain (MFIS), resulting from twin boundaries rearrangements, are excellent materials for novel actuators although enhanced brittleness and high costs are remaining the issues for applications. In polycrystalline state Ni-Mn-Ga alloys show small MFIS due to grain boundary constraints. By simple size reduction of the mentioned materials it is hardly possible to create quasi-two-dimensional MFIS actuators on the microscale with a pertinent out-of-plane performance. In pursuit of the trend for next generation materials and functions by design, in the present work we have developed a laminate composite as a prototype of microactuator with the out-of-plane stroke being driven by a framework of magnetostrain responsive Ni-Mn-Ga microparticles. The laminate consisted of the layer of crystallographically oriented Ni-Mn-Ga semi-free SC microparticles sandwiched between bonding polymer and Cu foils. Such design provided a particles isolation with a minimum constraint condition from the polymer. MFIS of the individual particles and the whole laminate composite was investigated by X-ray micro-CT 3D imaging. Both particles and laminate exhibited the same recoverable out-of-plane stroke produced by the particles´ MFIS of around 3% under 0.9 T. The developed microactuator design is promising for applications in the areas of micro-robotics, optical image stabilization in cameras, pumps for microfluidics etc.

Platinum Metallization of Polyethylene Terephthalate by Supercritical Carbon Dioxide Catalyzation and the Tensile Fracture Strength.

Polyethylene terephthalate (PET) is known to be highly inert, and this makes it difficult to be metallized. In addition, Pt electroless plating is rarely reported in the metallization of polymers. In this study, the metallization of biocompatible Pt metal is realized by supercritical CO2 (sc-CO2)-assisted electroless plating. The catalyst precursor used in the sc-CO2 catalyzation step is an organometallic compound, palladium (II) acetylacetonate (Pd(acac)2). The electrical resistance is evaluated, and a tape adhesion test is utilized to demonstrate intactness of the Pt layer on the PET film. The electrical resistance of the Pt/PET with 60 min of the Pt deposition time remains at a low level of 1.09 Ω after the adhesion test, revealing positive effects of the sc-CO2 catalyzation step. A tensile test is conducted to evaluate the mechanical strength of the Pt/PET. In-situ electrical resistances of the specimen are monitored during the tensile test. The fracture strength is determined from the stress value when the short circuit occurred. The fracture strength is 33.9 MPa for a specimen with 30 min of the Pt deposition time. As the Pt deposition time increases to 45 min and 60 min, the fracture strengths reach 52.3 MPa and 65.9 MPa, respectively. The promoted fracture strength and the decent electrical conductivity demonstrate the advantages toward biomedical devices.

Promoted mechanical properties and functionalities via Ta-tailored Ti-Au-Cr shape memory alloys towards biomedical applications.

In view of the urgent demands of shape memory alloys (SMAs) for biomedical applications due to the world population aging issue, the mechanical properties and functionalities of the biocompatible Ti-Au-Cr-based SMAs, which are tailored by Ta additions, have been developed in this study. The quaternary SMAs were successfully manufactured by physical metallurgy techniques and their mechanical properties and functionalities were examined. In the continuous tensile tests, it was found that the correlation between the yielding strength and phase stability followed a typical trend of mechanical behavior of SMAs, showing the lowest yielding strength at the metastable ß-parent phase. Functional mappings between the alloy strength and elongation revealed that compared to the Ta-free specimen, the ductility was promoted 50% while the strength remained intact through the 4 at.% introduction of Ta. Slight shape recovery was observed in the cyclic loading-unloading tensile tests during the unloading process and the highest shape recovery was found in the Ti-4 at.% Au-5 at.% Cr-4 at.% Ta specimen. This indicates that the 4 at.% Ta tailored Ti-Au-Cr SMAs could be a promising material for biomedical applications.

Achievement of Room Temperature Superelasticity in Ti-Mo-Al Alloy System via Manipulation of ω Phase Stability.

The achievement of room-temperature (RT) superelasticity in a Ti-Mo-Al ternary alloy system through the addition of a relatively high concentration of Al to manipulate the phase stability of the ω phase is realized in this study. The composition of the Ti-6 mol% Mo (Ti-11.34 mass% Mo) alloy was designated as the starting alloy, while 5 mol% Al (=2.71 mass% Al) and 10 mol% Al (=5.54 mass% Al) were introduced to promote their superelastic behavior. Among the alloys, Ti-6 mol% Mo-10 mol% Al alloy, which was investigated for the very first time in this work, performed the best in terms of superelasticity. On the other hand, Ti-6 mol% Mo and Ti-6 mol% Mo-5 mol% Al alloys exhibited a shape memory effect upon heating. It is worth mentioning that in the transmission electron microscopy observation, ω phase, which appeared along with ß-parent phase, was significantly suppressed as Al concentration was elevated up to 10 mol%. Therefore, the conventional difficulties of the inhibited RT superelasticity were successfully revealed by regulating the number density of the ω phase below a threshold.

Investigations of Effects of Intermetallic Compound on the Mechanical Properties and Shape Memory Effect of Ti-Au-Ta Biomaterials.

Owing to the world population aging, biomedical materials, such as shape memory alloys (SMAs) have attracted much attention. The biocompatible Ti-Au-Ta SMAs, which also possess high X-ray contrast for the applications like guidewire utilized in surgery, were studied in this work. The alloys were successfully prepared by physical metallurgy techniques and the phase constituents, microstructures, chemical compositions, shape memory effect (SME), and superelasticity (SE) of the Ti-Au-Ta SMAs were also examined. The functionalities, such as SME, were revealed by the introduction of the third element Ta; in addition, obvious improvements of the alloy performances of the ternary Ti-Au-Ta alloys were confirmed while compared with that of the binary Ti-Au alloy. The Ti3Au intermetallic compound was both found crystallographically and metallographically in the Ti-4 at.% Au-30 at.% Ta alloy. The strength of the alloy was promoted by the precipitates of the Ti3Au intermetallic compound. The effects of the Ti3Au precipitates on the mechanical properties, SME, and SE were also investigated in this work. Slight shape recovery was found in the Ti-4 at.% Au-20 at.% Ta alloy during unloading of an externally applied stress.

Enhancement of mechanical properties and shape memory effect of Ti-Cr-based alloys via Au and Cu modifications.

The requirements for biomedical materials have been raised greatly due to the rapidly aging global population. Shape memory alloys (SMAs) are indeed promising materials for biomedical applications due to their controllable shape deformation via the manipulation of temperature and/or stress. This study investigated the enhancement of the fundamental mechanical properties and the shape memory effect (SME) in the Ti-Cr-based alloys via the modification of Au and Cu. The quaternary Ti-Cr-Au-Cu alloys were successfully manufactured by physical metallurgy methods and their phase constitutions, mechanical properties, SME, and superelastic (SE) behaviors have been investigated in this study. Cold-workability, which was enhanced by the introduction of the Au element, was elaborated by the phase constitutions of the alloys. The ß-parent phase was stabilized to around body temperature by the introduction of the ß-stabilizers of Cr, Au, and Cu, and the functionalities of the specimens were revealed at the operating temperature. Perfect SME at the shape recovery rate of 100% was practiced by the substitution of Au by Cu and the mechanical properties, such as strength and ductility, were also enhanced. Functional mappings of the fundamental mechanical properties, which could be a helpful tool for the investigations of the quaternary Ti-Cr-Au-Cu alloys, were constructed in this work.

Mechanical Properties Enhancement of the Au-Cu-Al Alloys via Phase Constitution Manipulation.

To enhance the mechanical properties (e.g., strength and elongation) of the face-centered cubic (fcc) α-phase in the Au-Cu-Al system, this study focused on the introduction of the martensite phase (doubled B19 (DB19) crystal structure of Au2CuAl) via the manipulation of alloy compositions. Fundamental evaluations, such as microstructure observations, phase identifications, thermal analysis, tensile behavior examinations, and reflectance analysis, have been conducted. The presence of fcc annealing twins was observed in both the optical microscope (OM) and the scanning electron microscope (SEM) images. Both strength and elongation of the alloys were greatly promoted while the DB19 martensite phase was introduced into the alloys. Amongst all the prepared specimens, the 47Au41Cu12Al and the 44Au44Cu12Al alloys performed the optimized mechanical properties. The enhancement of strength and ductility in these two alloys was achieved while the stress plateau was observed during the tensile deformation. A plot of the ultimate tensile strength (UTS) against fracture strain was constructed to illustrate the effects of the introduction of the DB19 martensite phase on the mechanical properties of the alloys. Regardless of the manipulation of the alloy compositions and the introduction of the DB19 martensite phase, the reflectance stayed almost identical to pure Au.

Roles of TiO2 in the highly robust Au nanoparticles-TiO2 modified polyaniline electrode towards non-enzymatic sensing of glucose.

Along with the rise of diabetes mellitus issue, glucose sensor has become an imperative tool for healthcare. Studies have been widely conducted on electrode materials for glucose sensors; metal nanoparticles and/or oxide particles in its nano-size are reported to exhibit remarkable electrocatalytic activities in the non-enzymatic glucose sensors. However, the decoration processes of metal nanoparticles or nano-sized oxides are known to be tedious and time-consuming. In addition, the processes usually result in great amount of waste solution emission. In this study, therefore, an Au nanoparticles (NPs)-TiO2 modified polyaniline (PANI) composite is practiced towards the applications of non-enzymatic glucose sensors, by using a facile and time-saving thermal reduction and by electrodeposition techniques with low waste solution emission. Au NPs, which is modified with TiO2 nanoparticles in its optimized amount, performs the highest electrocatalytic activity to the oxidation of glucose in alkaline solution. The stability of Au NPs-TiO2/PANI is superior to those of most reported results over 70 days. The sensitivity and detection limit are 379.8 µA mM-1 cm-2 and 0.15 µM, respectively. High selectivity of Au NPs-TiO2/PANI is also confirmed by the interference test. Spill-over effect of OH- between Au NPs and TiO2, which is the main reason for the improved catalytic activity, is described in this study.

A strategy to optimize the thermoelectric performance in a spark plasma sintering process.

Spark plasma sintering (SPS) is currently widely applied to existing alloys as a means of further enhancing the alloys' figure of merit. However, the determination of the optimal sintering condition is challenging in the SPS process. This report demonstrates a systematic way to independently optimize the Seebeck coefficient S and the ratio of electrical to thermal conductivity (σ/κ) and thus achieve the maximum figure of merit zT = S(2)(σ/κ)T. Sb2-xInxTe3 (x = 0-0.2) were chosen as examples to validate the method. Although high sintering temperature and pressure are helpful in enhancing the compactness and electrical conductivity of pressed samples, the resultant deteriorated Seebeck coefficient and increasing thermal conductivity eventually offset the benefit. We found that the optimal sintering temperature coincides with temperatures at which the maximum Seebeck coefficient begins to degrade, whereas the optimal sintering pressure coincided with the pressure at which the σ/κ ratio reaches a maximum. Based on this principle, the optimized sintering conditions were determined, and the zT of Sb1.9In0.1Te3 is raised to 0.92 at 600 K, showing an approximately 84% enhancement. This work develops a facile strategy for selecting the optimal SPS sintering condition to further enhance the zT of bulk specimens.

Therapeutic effect of topical gamma-linolenic acid on refractory uremic pruritus.

BACKGROUND: Pruritus is a bothersome symptom affecting up to 80% of dialysis patients. Lymphocyte and cytokine interaction has an important role in the pathogenesis of uremic pruritus. Gamma-linolenic acid (GLA) is associated with immune modulation of T lymphocytes and lymphokines. The aim of this study is to determine whether topical GLA can attenuate uremic pruritus. METHODS: Seventeen dialysis patients with refractory uremic pruritus who passed the screening criteria entered a prospective, randomized, double-blind, placebo-controlled, crossover study. They stopped all antipruritic therapy at least 2 weeks before the study and were randomly assigned to treatment with either GLA 2.2% cream or placebo-based cream applied to the entire body after taking a bath once a day and to pruritic sites 3 times a day for 2 weeks, and then the reverse treatment after a 2-week washout period. Severity of pruritus was evaluated by using a traditional visual analogue scale (VAS) and a modified questionnaire method (pruritus score [PS]). Hemogram, aspartate and alanine aminotransferases, bilirubin, albumin, blood urea nitrogen, creatinine, calcium, phosphate, and intact parathyroid hormone were measured. RESULTS: Sixteen patients completed the study; 1 patient was withdrawn because of an allergic skin reaction. There were no significant differences between groups except for sex distribution. Median VAS and PS values between groups did not differ significantly at baseline. There is a greater antipruritic effect of GLA based on evaluation with both the VAS and PS. There is persistence of a residual effect into the second treatment period after GLA treatment. CONCLUSION: GLA-rich cream is better than placebo-based cream for alleviating uremic pruritus. It is a useful adjuvant in the management of refractory uremic pruritus.