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Background: Obesity represents an epidemic of rising numbers worldwide year after year. In the Orthopedic field, obesity is one of the major causes leading to osteoarthritis needing Total Joint Arthroplasty (TJA). Still, contextually, it represents one of the most significant risk factors for joint replacement complications and failures. So, bariatric Surgery (BS) is becoming a valuable option for weight control and mitigating obesity-related risk factors. This review of the literature and meta-analysis aims to evaluate periprosthetic joint infections (PJI) and surgical site infections (SSI) rates in patients who underwent TKA after BS compared to obese patients without BS. Methods: Systematic review was performed according to Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines up to October 2023. We included longitudinal studies comparing obese patients who underwent total knee arthroplasty after bariatric surgery (study group) and obese patients who underwent TKA (control group). The surgical site infection and Periprosthetic joint infection rate were compared among groups using a meta-analytical approach. Results: The online database and references investigation identified one hundred and twenty-five studies. PJI rate differed significantly among groups, (z = -21.8928, p < 0.0001), with a lower risk in the BS group (z = -10.3114, p < 0.0001), for SSI, instead, not statistically significance were recorded (z = -0.6784, p = 0.4975). Conclusions: The current Literature suggests that Bariatric Surgery can reduce infectious complications in TKA, leading to better outcomes and less related costs treating of knee osteoarthritis in obese patients. [ABSTRACT FROM AUTHOR]

Atemoya (Annona × atemoya Mabb.), a climacteric fruit of the Annonaceae family, is becoming increasingly popular due to its organoleptic and nutritional properties. Anthracnose, a fungus of the Colletotrichum genus, is one of the most serious diseases in orchards, causing significant damage if not controlled, so producers use phytosanitary products. The current study sought to investigate the quality of atemoya fruits after harvest in an orchard with anthracnose controlled by Cu(OH)2 application: T1—no Cu(OH)2, T2—7.8 mL Cu(OH)2 L1 divided into two applications, T3—15.6 mL Cu(OH)2 L1 divided into four, T4—8.0 mL Cu(OH)2 L1 divided into eight, and T5—13.0 mL Cu(OH)2 L1 divided into thirteen applications. The sugar profile of fruits was examined, as well as MDA, H2O2, and quality parameters such as pH, mass, soluble solids, titratable acidity, and maturation index. MDA, such as H2O2, can function as a signal molecule. Eight applications of 1.0 mL L-1 Cu(OH)2 resulted in increased concentrations of H2O2 and MDA, signal molecules involved in sugar modification profiles such as glucose, fructose, and trehalose. It also had a high titratable acidity, a lower maturation index, better fruit quality, and a longer shelf life. [ABSTRACT FROM AUTHOR]

Continuous nonlinear transmission lines (NLTLs), also known as gyromagnetic lines, consist of ferrite-based magnetic cores biased by an external magnetic field. Over the past years, many analytical and experimental studies have predicted the rise time reduction of the input pulse to the range of a few nanoseconds or even hundreds of ps experimentally observed in such gyromagnetic lines. This effect, known as pulse sharpening, is investigated in this paper built on a model based on a periodic structure of inductive–capacitive cells in series with magnetization-driven voltage sources expressed by the one-dimensional form (1D) of the Landau–Lifshitz–Gilbert (LLG) gyromagnetic equation. We explore the model through parametric study under various input–pulse parameters to understand the physics behind the ferrimagnetic material responses. Moreover, the numerical results obtained from computational simulations using Mathematica (v. 12.1) show how the line parameters (input voltage, damping constant, saturation magnetization, and length) affect the sharpening effect, which is quantified by the switching time. Our results on ferrite-loaded coaxial lines have confirmed many results found in the literature. We validated with a good agreement the proposed model with the result obtained by Dolan in 1993 using the same 1D form of the LLG equation, thus showing that the model proposed here is suitable to quantify the sharpening effect produced by a gyromagnetic NLTL. [ABSTRACT FROM AUTHOR]

Successful wafer-scale layer transfer from high-quality 2-in. diameter bulk gallium nitride substrates was demonstrated using the Controlled Spalling technique. The crystal quality of both the as-fractured bulk substrate and the spalled GaN film was assessed using transmission electron microscopy analysis, and the defect density was below the detection limit (mid 107 cm-2) for both samples. By using the experimentally determined critical conditions for tensile stress and thickness of the Ni stressor layer, an effective fracture toughness KIC of 1.7MPa √m could be calculated for [0001] fracture using the Suo and Hutchinson mechanical model. The resulting inplane contraction of the GaN film after spalling permitted a novel method for measuring film strain without knowledge of the elastic properties of the material. This was used to measure the Raman E2(high) peak shift coefficient of Δω(cm-1)=1411ε which, when converted to a stress coefficient (2.95 cm-1/GPa), was in agreement with only one other literature value. [ABSTRACT FROM AUTHOR]

Successful wafer-scale layer transfer from high-quality 2-in. diameter bulk gallium nitride substrates was demonstrated using the Controlled Spalling technique. The crystal quality of both the as-fractured bulk substrate and the spalled GaN film was assessed using transmission electron microscopy analysis, and the defect density was below the detection limit (mid 107 cm−2) for both samples. By using the experimentally determined critical conditions for tensile stress and thickness of the Ni stressor layer, an effective fracture toughness KIC of 1.7 MPa √m could be calculated for [0001] fracture using the Suo and Hutchinson mechanical model. The resulting in-plane contraction of the GaN film after spalling permitted a novel method for measuring film strain without knowledge of the elastic properties of the material. This was used to measure the Raman E2(high) peak shift coefficient of Δω(cm−1) = 1411ε which, when converted to a stress coefficient (2.95 cm−1/GPa), was in agreement with only one other literature value. [ABSTRACT FROM AUTHOR]

Polymers are plastic materials used as insulators in power supplies, pulsers, transformers, etc., because of their low cost and excellent insulating properties. However, in several applications, the insulating performance of these materials is limited by the surface flashover instead of the dielectric bulk breakdown (BD). On the other hand, many works have demonstrated that the material hydrophobicity has a huge effect on the increase of resistance to surface flashover in polymers. In this article, to change this material property, the plasma immersion ion implantation (PIII) technique has been used for the treatment of sample surfaces of two important polymers: ultrahigh molecular weight polyethylene (UHMWPE) and poly-methyl-methacrylate (PMMA) used in medical and industrial applications, respectively. By means of the PIII treatment, it was shown that the surface BD voltage of such polymers has increased, improving the resistance to surface flashover. Contact angle diagnostic and atomic force microscopy (AFM) were measured, respectively, for the surface hydrophobicity and roughness to correlate with the increase of the surface BD voltage. Moreover, a special BD testing pulser is employed to assess the polymer resistance to surface flashover by measuring the corresponding BD voltage under atmospheric pressure. [ABSTRACT FROM AUTHOR]

Lumped nonlinear transmission lines (NLTLs) have been studied for the generation of radio frequency (RF) signals in the range of the order of tens of megahertz (MHz) up to a few hundreds of MHz depending on the nonlinear element used in the LC line. The oscillations obtained at the output of these lines are applied in defense mobile platforms and communications systems. Low power NLTLs use varactor diodes as nonlinear elements, which show a strong nonlinear effect with capacitance variation of the order of 90% at their p-n junction with the applied voltage, which is an excellent performance to obtain oscillations at the line output. However, these semiconductor devices operate at low voltage, producing small voltage modulation depth (VMD), low power, and consequently reduced signal range. Looking for increasing the VMD of the signal generated with NLTLs, this work developed a RF amplifier using a metal–oxide–semiconductor field-effect transistor (MOSFET) model RD06HVF1. A 30-section line using varactor diodes MV209 as nonlinear elements can work as an RF source to obtain oscillations with a frequency of 33.3 MHz at the line output. Using SPICE simulations, it has been demonstrated that an amplifier circuit connected to the output of this varactor diode transmission line can produce an increase of the VMD produced at line output from 10.7 to 40 V approximately, thus allowing higher level power to electromagnetic wave propagation and consequently higher signal range. Experimental comparison using a printed circuit board (PCB) prototype with the corresponding simulation will be also shown. [ABSTRACT FROM AUTHOR]

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Nonlinear transmission lines (NLTLs) have been studied for high-power RF generation with good prospects of applications in pulse radars for remote sensing (SARs) and disruption of communications in the battlefield, for instance. In this paper, two 30-section hybrid NLTLs built using nonlinear inductors and capacitors (2.2- and 10-nF barium titanate ceramic capacitors with 10- $\mu \text{H}$ ferrite bead inductors) will be described. For the test, the line is fed by a negative input pump pulse generated by a 1 kV discharge of a 0.75- $\mu \text{F}$ storage capacitor via a fast 50-ns switching system composed by an insulated gate bipolar transistor switch and its gate circuit driver. In the hybrid line tests, using 2.2-nF ceramic capacitors the maximum soliton generation packet obtained on the middle section had a frequency of the order of 33 MHz with voltage modulation depth (VMD) of around 700 V. For every single shot, approximately 10 RF cycles with small damping were noted. With the hybrid line using 10-nF ceramic capacitors the soliton generation obtained on the middle section reached a frequency of the order 10 MHz, and VMD of around 200 V. The main conclusion from this experiment is that hybrid lumped NLTLs may be used to achieve RF in megahertz range with higher VMD compared their counterparts (i.e., capacitive or inductive lines) because of their stronger nonlinearity with the use of both nonlinear elements. [ABSTRACT FROM AUTHOR]

In recent years, nonlinear transmission lines (NLTLs) have been investigated for high-power radio frequency generation. High-power waves produced using NLTLs can be applied in mobile defense platforms and satellite communications as they can reach tens of MW of peak power. Their principle of operations is based on the nonlinearity of inductive and/or capacitive lumped elements used in such lines. In this paper, an NLTL using commercial ceramic capacitors as nonlinear elements and linear inductors was simulated and built. Experimental and simulated results show good agreement, validating the model of ceramic capacitors. The frequency obtained from soliton generation at the output of the line was about 4 MHz with peak power of the order of 8 kW. [ABSTRACT FROM PUBLISHER]

Nonlinear transmission lines (NLTLs) are nonlinear LC ladder networks that can act as a nonlinear and dispersive medium, thus allowing the generation of soliton bursts. Several papers have been published indicating that NLTLs offer a new option for pulse shaping and RF generation. In this paper, we investigated the response of an NLTL driven by three different pulse shapes: a rectangular, a half sine, and a triangular waveform. The performance of the NLTL was evaluated through time- and frequency-domain analysis of the RF signal sampled at the 29th section of a 30-section capacitive NLTL. The frequency of the generated RF signal is correlated with the shape of the input signal, whereby the output frequency can be adjusted by the amplitude-time characteristics of the pulse at the input of the capacitive NLTL. Higher frequency oscillations, around 30 MHz, were generated by the rectangular wave train due to its shorter rise time. The propagation of solitons along the NLTL is influenced by the input pulse rise time. Namely, the rectangular pulse showed smaller delay time as it had the shortest rise time (less than 10 ns). Maximum efficiency was obtained for the input pulsewidth of 150 ns under a duty cycle of 1/3 for the three pulse shapes (rectangular, half sine, and triangular), and this combination of parameters yielded the highest RF conversion efficiency of the NLTL. The capacitive NLTL showed a higher RF conversion efficiency (16.4%) when driven by the rectangular input signal. [ABSTRACT FROM AUTHOR]

Lead zirconate titanate (PZT)-type ceramics used as piezoelectric sensors have electrodes made by metallic film deposition on the ceramic substrate, which has low adherence on substrate surface. During the welding process in electronic component manufacture, the metallic film releases from surface due to the electrode delamination caused by the large difference in thermal expansion gradients between the film and ceramic. Delamination is a serious problem found in the manufacture of ceramic capacitors since the metallic electrode is split into several layers, leading to a component failure as the electrode is not in contact with the ceramic surface anymore. Therefore, in order to increase the film adherence on the ceramic it is proposed in this paper to treat the PZT samples covered with silver metallic films by means of plasma immersion ion implantation (PIII) technique using a high voltage 100-kV/1- \mus stacked Blumlein pulser. By using this technique, it is shown that the mechanical adherence of the electrode metallic silver film is increased, which allows the welding process of terminals for the piezoelectric device manufacture without film release failure. Thermal stress relief treatment known as annealing process was also used in this paper as an alternative to the PIII method for increasing the film anchoring on ceramic substrate. [ABSTRACT FROM PUBLISHER]

Low loss dielectric materials with high permittivity and nonlinear behavior are essential for use in capacitive nonlinear transmission lines (NLTLs) for RF generation. NLTLs have a great potential to generate soliton waves for high-power microwave applications in mobile defense platforms and satellite communications. In this paper, the dielectric properties of a piezoelectric capacitor based on lead-zirconate-titanate (PZT) was characterized in a broadband frequency range from 10 MHz to 1 GHz for use in NLTLs. Three commercial ceramic capacitors made of barium titanate (BaTiO3) were also assessed for comparison with the PZT capacitor. The characterization of materials consisted of measuring the relative dielectric constant (real and imaginary parts) as function of the applied voltage and frequency to calculate the loss tangent of the material. The results showed that PZT material has a better performance for use in NLTLs than barium titanate because of its lower losses. As discussed here, however, the use of PZT and barium titanate-based materials in NLTLs are compromised by the self-resonant frequency of the capacitors because of the inherent parasitic inductance associated with the capacitor at high frequencies. [ABSTRACT FROM PUBLISHER]

Recently, the research and development activities for replacing Pb-containing solders with Pb-free solders have been intensified due to both competitive market pressures and environmental issues. As a result of these activities, a few promising candidate solder alloys have been identified, mainly, Sn-based alloys. A key issue affecting the integrity and reliability of solder joints is the interfacial reactions between a molten solder and surface finishes in the solder joint structures. In this paper, a fundamental study of the interfacial reactions between several Pb-free candidate solders and surface finishes commonly used in printed-circuit cards is reported. The Pb-free solders investigated include Sn-3.5 Ag, Sn-3.8 Ag-0.7 Cu, and Sn-3.5 Ag-3.0 Bi. The surface finishes investigated include Cu, Au/Ni(P), Au/Pd/Ni(P), and Au/Ni (electroplated). The reaction kinetics of the dissolution of surface finishes and intermetallic compound growth have been measured as a function of reflow temperature and time. The intermetallic compounds formed during reflow reactions have been identified by SEM with energy dispersive x-ray spectroscopy. [ABSTRACT FROM PUBLISHER]

In this letter, we demonstrate the effectiveness of the controlled spalling technology for producing high-efficiency (28.7%) thin-film InGaP/(In)GaAs/Ge tandem solar cells. The controlled spalling technique was employed to separate the as-grown solar cell structure from the host Ge wafer followed by its transfer to an arbitrary Si support substrate. The structural and electrical properties of the thin-film tandem cells were examined and compared against those on the original bulk Ge substrate. The comparison of the electrical data suggests the equivalency in cell parameters for both the thin-film (spalled) and bulk (non-spalled) cells, confirming that the controlled spalling technology does maintain the integrity of all layers in such an elaborate solar cell structure. [ABSTRACT FROM AUTHOR]

The undercooling of flip-chip Pb-free solder bumps was investigated by differential scanning calorimetry (DSC) to understand the effects of solder composition and volume, with and without the presence of an under bump metallurgy (UBM). A large amount of the undercooling (as large as 90 °C) was observed with Sn-rich, flip-chip size solder bumps sitting in a glass mold, while the corresponding undercooling was significantly reduced in the presence of a wettable UBM surface. In addition, the solidification of an array of individual solder bumps was monitored in situ by a video imaging technique during both heating-up and cooling-down cycles. Data obtained by the optical imaging method were used to complement the DSC thermal measurements. A random solidification of the array of bumps was demonstrated during cooling, which also spans a wide temperature range of 40-80 °C. In contrast, an almost simultaneous melting of the bumps was observed during heating. [ABSTRACT FROM AUTHOR]