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Echocardiographic quantification of mitral regurgitation (MR) remains challenging, requiring dedicated image acquisition, and is limited by potential error from geometric assumptions of annular dimensions. Volume is a product of area and flow and assuming proportional mitral/aortic areas, an increased mitral-inflow volume compared to LV/RV-outflow semi-quantitatively represents greater MR regurgitant volume. Therefore, we investigated the feasibility and diagnostic performance of the mitral-aortic velocity-time integral(VTI) ratio in isolated MR. We also investigated the use of the mitral-pulmonary VTI ratio as an alternative in clinical situations where the LV outflow tract(LVOT) VTI could not be used. We reviewed 166 consecutive patients (33%, n = 54 severe MR by multi-parameter integrated expert opinion). Pulsed wave Doppler VTI at the mitral leaflet tips and the left ventricular outflow and continuous-wave Doppler of the RV outflow tract were measured individually and independently by blinded readers(expert and trainee status) to derive the ratio. Receiver operator characteristic area under the curve(AUC) comparison was calculated and compared with effective regurgitant orifice area(EROA > 40 mm), regurgitant volume(RVol > 60mL), vena contracta(VC > 0.7 cm), E-velocity > 1.2 cm, systolic flow reversal(SFR), left atrial and ventricular dilatation. Increasing ratio was associated with severe MR(AUC 0.94) with optimal threshold defined at 1.3. This provided significant discrimination for severe MR(AUC 0.81) compared to EROA(0.68), VC(0.52), LV dilatation(0.69), LA dilatation(0.70), SFR(0.73), E-velocity(0.68) all p < 0.05, with sensitivity 82% and specificity 94%. The mitral-pulmonary VTI ratio demonstrated similar discrimination(AUC 0.92) with optimal threshold defined at 1.14. Excellent inter-observer reproducibility(intra-class correlation 0.97) was seen between trainee and expert readers. There was no difference in AUC comparison by MR mechanism or patient rhythm. The mitral-aortic and mitral-pulmonary VTI ratios are simple, geometric-free parameters feasibly reproducible from routine echocardiographic datasets and are excellent discriminative tools for severe MR. Readers should consider integration of this parameter in routine reporting. [ABSTRACT FROM AUTHOR]

To eradicate the losses in high-frequency wireless transmission systems, glass-vias is favored over silicon-vias for the packaging of radio frequency devices. However, during machining of glass vias, poor scavenging of sludge and electrolyte scarcity in the working region degrades the ECDM performance. To cope up with these problems, this study is an attempt to induce electrolyte stirring using a magnetic stirrer in the ECDM, called S-ECDM. An electrostatic study for electrochemical cells of ECDM was performed to analyze the discharge behavior of electrodes for tool selection. A Gaussian based thermal finite element modelling (FEM) has been carried out for ECDM and S-ECDM by considering pulsed-discharges with regards to voltage, electrolyte temperature, pulse on time and partition energy. The temperature profiles were utilized in the estimation of machining rate (MR) in the micro drilling of borosilicate glass. Subsequently, simulation as well as experimental results suggested around 50% higher MR in S-ECDM than ECDM. Furthermore, characterizations have been performed to substantiate the process mechanism of the proposed process in the ambit of flushing, etching and surface roughness of micro holes. Owing to its performance and process stability, S-ECDM can be considered as a commercially viable process. [ABSTRACT FROM AUTHOR]

For satellites in Very Low Earth Orbit (VLEO) or the upper atmosphere, Air-Breathing Electric Propulsion (ABEP) can be used to counteract the drag effects of the atmosphere or provide attitude control without the need for onboard propellant storage. The Dense Plasma Focus (DPF) inspired the design of an ABEP Pulsed Plasma Thruster (TAMU PPT) which takes advantage of the simplicity, scalability, and high energy density of the DPF. This work details the design and testing of a PPT for use on satellites in the upper atmosphere. Testing was conducted at a variety of pressures and pulsing energies to determine which conditions provide maximum thrust and thrust to power ratios (TPR). It was found through single pulse experiments that a pressure of 6.3 hPa (corresponding to an altitude of about 35 km) and an energy per pulse of 9 J yield a TPR of 21 mN/kW. High frequency operation at 20 Hz in similar conditions showed a TPR of up to 28 mN/kW with a corresponding thrust of 4.8 mN. High speed imaging of the plasma plume found plasma velocities in excess of 2 km/s and identified metal ejecta with velocities up to 350 m/s. The pinching phenomenon associated with a DPF was also observed and a plasma jet velocity up to 50 km/s was recorded. The TPR of the TAMU PPT demonstrated in this work is comparable to that of other ABEP thrusters, however the TAMU PPT has an advantage when comparing thrust density. The TAMU PPT has a thrust density between 4.8 and 19 mN/cm2 while other ABEP thrusters have thrust densities between 0.019 and 0.36 mN/cm2. [ABSTRACT FROM AUTHOR]

An array of published cell-based and small animal studies have demonstrated a variety of exposures of cancer cells or experimental carcinomas to electromagnetic (EM) wave platforms that are non-ionizing and non-thermal. Overall effects appear to be inhibitory, inducing cancer cell stress or death as well as inhibition in tumor growth in experimental models. A variety of physical input variables, including discrete frequencies, amplitudes, and exposure times, have been tested, but drawing methodologic rationale and mechanistic conclusions across studies is challenging. Nevertheless, outputs such as tumor cytotoxicity, apoptosis, tumor membrane electroporation and leak, and reactive oxygen species generation are intriguing. Early EM platforms in humans employ pulsed electric fields applied either externally or using interventional tumor contact to induce tumor cell electroporation with stromal, vascular, and immunologic sparing. It is also possible that direct or external exposures to non-thermal EM waves or pulsed magnetic fields may generate electromotive forces to engage with unique tumor cell properties, including tumor glycocalyx to induce carcinoma membrane disruption and stress, providing novel avenues to augment tumor antigen release, cross-presentation by tumor-resident immune cells, and anti-tumor immunity. Integration with existing checkpoint inhibitor strategies to boost immunotherapeutic effects in carcinomas may also emerge as a broadly effective strategy, but little has been considered or tested in this area. Unlike the use of chemo/radiation and/or targeted therapies in cancer, EM platforms may allow for the survival of tumor-associated immunologic cells, including naïve and sensitized anti-tumor T cells. Moreover, EM-induced cancer cell stress and apoptosis may potentiate endogenous tumor antigen-specific anti-tumor immunity. Clinical studies examining a few of these combined EMplatform approaches are in their infancy, and a greater thrust in research (including basic, clinical, and translational work) in understanding how EM platforms may integrate with immunotherapy will be critical in driving advances in cancer outcomes under this promising combination. [ABSTRACT FROM AUTHOR]

The ejector is a crucial component of the hydrogen circulation system of proton exchange membrane fuel cell (PEMFC), which is widely used because of its simple structure, reliable operation, and no additional power consumption. However, the current research on pulsed ejectors is still lacking and in-depth. In this study, CFD modeling is conducted on the ejector, and the pulsed gas flow is simulated by user define function (UDF), and the influence of the pulsed gas flow on the entrainment performance of the ejector is analyzed. The results show that, compared with the steady-state condition, the entrainment performance of the ejector using pulsed gas flow under different primary flow pressures is improved, and the maximum entrainment ratio is 3.195 under steady-state conditions and 3.507 under transient conditions, which is increased by 9.8%. The effect is especially pronounced at low pressure, where the entrainment ratio increases by 16.6%. And by comparing the gas flow of different pulse frequencies, it is found that when the pulse frequency is 1Hz, the ejector has the best entrainment performance. • The ejector with pulsed gas flow has significantly better entrainment performance. • At the low primary inlet pressure, the pulsed gas flow has a good effect on the entrain ment performance. • Pulsed gas flow can form a lower low-pressure area at the nozzle exit. • When the frequency of the pulsed gas flow is 1Hz, the entrainment ratio is maximum. [ABSTRACT FROM AUTHOR]

An array of published cell-based and small animal studies have demonstrated a variety of exposures of cancer cells or experimental carcinomas to electromagnetic (EM) wave platforms that are non-ionizing and non-thermal. Overall effects appear to be inhibitory, inducing cancer cell stress or death as well as inhibition in tumor growth in experimental models. A variety of physical input variables, including discrete frequencies, amplitudes, and exposure times, have been tested, but drawing methodologic rationale and mechanistic conclusions across studies is challenging. Nevertheless, outputs such as tumor cytotoxicity, apoptosis, tumor membrane electroporation and leak, and reactive oxygen species generation are intriguing. Early EM platforms in humans employ pulsed electric fields applied either externally or using interventional tumor contact to induce tumor cell electroporation with stromal, vascular, and immunologic sparing. It is also possible that direct or external exposures to non-thermal EM waves or pulsed magnetic fields may generate electromotive forces to engage with unique tumor cell properties, including tumor glycocalyx to induce carcinoma membrane disruption and stress, providing novel avenues to augment tumor antigen release, cross-presentation by tumor-resident immune cells, and anti-tumor immunity. Integration with existing checkpoint inhibitor strategies to boost immunotherapeutic effects in carcinomas may also emerge as a broadly effective strategy, but little has been considered or tested in this area. Unlike the use of chemo/radiation and/or targeted therapies in cancer, EM platforms may allow for the survival of tumor-associated immunologic cells, including naïve and sensitized anti-tumor T cells. Moreover, EM-induced cancer cell stress and apoptosis may potentiate endogenous tumor antigen-specific anti-tumor immunity. Clinical studies examining a few of these combined EM-platform approaches are in their infancy, and a greater thrust in research (including basic, clinical, and translational work) in understanding how EM platforms may integrate with immunotherapy will be critical in driving advances in cancer outcomes under this promising combination.

This study utilizes the Kerr effect in the analysis of a pulsed electric field (intensity ~108 V/m, limited by the liquid dielectric strength) in deionized water at the sub-nanosecond time scale. The results provide information about voltage waveforms at the field-producing anode (160 kV peak, du/dt > 70 kV/ns). The analysis is based on detecting the phase shifts between measured and reference pulsed laser beams (pulse width, 35 ps; wavelength, 532 nm) using a Mach–Zehnder interferometer. The signal-to-noise ratio of the detected phase shift is maximized by an appropriate geometry of the field-producing anode, which creates a correctly oriented strong electric field along the interaction path and simultaneously does not electrically load the feeding transmission line. The described method has a spatial resolution of ~1 μm, and its time resolution is determined by the laser pulse duration.

The use of surface acoustic waves (SAW) in cell biology has gained high attention in the past years. Previous works show that SAW treatment of artificial wounds in vitro can accelerate wound healing by up to +135%. However, little is known about the mechanobiology behind these effects, and a stimulation has only been proven for continuous SAW signals so far. We here show that the stimulation efficacy observed in previous studies is preserved for pulsed stimuli applied to Madin-Darby canine kidney (MDCK-II) cells in wound healing assays on SAW chips at a resonance frequency f SAW = 160 MHz. Moreover, for a reproducible and reliable image analysis, we present the SegFormer-based deep learning algorithm Neural Cell Edge Detector for the cell edge segmentation and image binarization, that allows an automated determination of the stimulation efficacy. With these tools, we explore a wider range of applicable SAW intensities up to P in = 21 dBm (128 mW) with a maximum stimulation efficacy of E = 201%. We show that the order of magnitude of the stimulation effect is reproducible under the variation of SAW signal characteristics power P in, duty cycle D and pulse width τ, while the mean energy over time is constant. Below a distinct pulse duration limit τ = 100 ms, no direct stimulation effect was observed. From a mechanobiological point of view, these findings and time scales could narrow down the potentially triggered cellular mechanisms during the stimulation. [ABSTRACT FROM AUTHOR]

This paper introduces cathodic gear tools designed for non-contact modification of spur gears through pulsed electrochemical flank modification. Operating with continuous rotary motion, these tools achieve profile crowning, lead crowning, tip relieving, root relieving, and end relieving. Anodic workpiece gears experience constant or variable reciprocating velocity based on the modification type. Experimental investigations confirm that the tools not only achieve the intended flank modification but also reduce flank surface roughness, eliminating hob cutter marks and cracks from the modified spur gear surfaces. The magnitude of intended modifications increases with higher voltage and longer modification duration. Notably, root relieving requires a longer duration (20 minutes) compared to other modifications (12 minutes). Details of variation in surface roughness and surface morphology using scanning electron microscopy are also presented to validate the developed mechanism. [ABSTRACT FROM AUTHOR]

We report high‐power InGaN back‐barrier AlGaN/GaN high electron mobility transistors with the gate placed closer to the source with an Au‐filled groove in the SiC substrate near the drain end. An InGaN back‐barrier is known to reduce short‐channel effects at high drain‐to‐source (VDS) voltage. However, the improvement is realized at the cost of reduced two‐dimensional electron gas density (ns) and saturation drain‐to‐source (IDS,SAT) current. Here, we demonstrate that both ns and IDS,SAT are recovered when the gate is appropriately delineated near the source. The junction temperature increases at higher VDS, which tends to deteriorate the power performance and suppress the benefits from higher IDS,SAT. This problem is contained by further thinning down the SiC substrate near the drain by creating a backside groove using deep reactive‐ion‐etching and filling it with Ti/Au. An enhanced thinned‐down substrate distributes the lateral electric field uniformly near the drain end, compounding its benefits with an asymmetric gate and lower junction temperature. The proposed device shows an output power of Pout = 6.7 W mm−1 at VDS = 28 V at 15 GHz for a 200 nm gate length (LG). [ABSTRACT FROM AUTHOR]

Abstract Background Lumbar radicular pain (LRP) is one of the most encountered complaints in neurosurgical practice that pose a challenge in its management as adequate pain control, which is not always achieved. Objective The aim of this study was to evaluate the role of pulsed radiofrequency as a minimally invasive tool in the management of lumbar radicular pain of lumbar discogenic origin. Methods This is a prospective study that included 20 patients with lumbar radicular pain with radiological evidence of lumbar disc prolapse, who have been subjected to pulsed radiofrequency. Results The mean preoperative visual analogue score was 71 ± 14.38 dropped to a mean of 43.5 ± 21.47 at six-month follow-up. Seventy percentage of the study population had a satisfactory outcome, which did not correlate with the age, sex, or body mass index of the patients. Conclusions Pulsed radiofrequency is a safe and useful tool that may be used in the management of lumbar radicular pain.

Background: Recent innovations, such as hydrosurgery, ultrasound therapy, and plasma-mediated bipolar radio-frequency ablation therapy could represent an alternative to conventional debridement in many cases, especially for chronic non-healing wounds. Pulsed electromagnetic field (PEMF) has been used clinically as an intervention to enhance healing of chronic infected wound. The aim is to evaluate the effect of PEMF therapy on healing of chronic wounds, as regard timing and quality of healing. Methods: Fifty cases with chronic wounds, according to inclusion and exclusion criteria, the patient's age ranged from 20 -70 years, from outpatient clinic of military or transferred through civilian outpatient's clinic in different hospitals and specific diabetic foot centers. They are diagnosed as infected resistant chronic wounds depending on clinical, laboratory and radiological investigations due to various reasons will be managed by PEMF therapy. Results: There were statistically significant associations between treatment outcomes and pain (p < /em> =0.018), edema (p =0.005), number of sessions (p =0.008). On the other hand, we found that there were statistically significant associations between complication rates and treatment outcome (p < /em>=0.008), microbial eradication (p < /em> =0.002). Conclusion: the PEMF therapy is a safe and effective treatment option for patients with chronic, resistant, wounds. The current study shows that the PEFM achieved a high success rate. In addition, our analysis showed that achieving complete closure of the wound can be associated with significant symptomatic relief and few incidences of complications. Nevertheless, further studies are still needed to confirm our findings.

A pulsed RF discharge is considered experimentally as a working process of an RF ion source. It is shown that an increase in the ion current can be obtained in comparison with the continuous operation mode when such a discharge is operating. This increase is the greater, the greater the difference between the characteristic time of the drop of the ion current after turning off the RF power and the rise time of the ion current when the RF power is turned on. The pulsation parameters at which the ion current is maximized are estimated. It is shown that an external constant longitudinal magnetic field in the range of 0–7.2 mT nonmonotonically affects the maximum and equilibrium value of the ion current in a pulse and does not affect the decrease rate of the ion current after the RF power is turned off. [ABSTRACT FROM AUTHOR]

Herein, we discuss the modeling of the pulsed electric field (PEF) process, with attention focused on the originally intended application of pasteurization of liquid foods. We review literature on three classes of models. First are the models for electroporation (of molecular scale), derived from physics and physical chemistry considerations, and their extension to probabilistic approaches which treat pore formation as a random process. We discuss the more recent approaches involving molecular dynamics. Then, we consider treatment-chamber and system scale models, which are based on continuum physics approaches, and rely on computational Multiphysics codes for their solution. We then discuss the base assumptions for several modeling studies. Next, we consider models for inactivation kinetics for bacteria exposed to PEF, including the first order, Hulsheger, Peleg and Weibull models. We close with discussions of other models and experimental approaches for model verification and obtaining kinetic parameters from continuous flow PEF systems.

Background: Lumbar radicular pain (LRP) is one of the most encountered complaints in neurosurgical practice that pose a challenge in its management as adequate pain control, which is not always achieved. Objective: The aim of this study was to evaluate the role of pulsed radiofrequency as a minimally invasive tool in the management of lumbar radicular pain of lumbar discogenic origin. Methods: This is a prospective study that included 20 patients with lumbar radicular pain with radiological evidence of lumbar disc prolapse, who have been subjected to pulsed radiofrequency. Results: The mean preoperative visual analogue score was 71 ± 14.38 dropped to a mean of 43.5 ± 21.47 at six-month follow-up. Seventy percentage of the study population had a satisfactory outcome, which did not correlate with the age, sex, or body mass index of the patients. Conclusions: Pulsed radiofrequency is a safe and useful tool that may be used in the management of lumbar radicular pain. [ABSTRACT FROM AUTHOR]

This paper describes tip relieving of spur gears by pulsed electrochemical flank modification (PECFM) process by a novel designed cathodic gear tool and apparatus. This work reports experimental findings on tip relieving and surface finish by varying the concentration, flow rate, and temperature of the electrolyte, modification duration, and cathodic gear rotational speed at four levels each and using predetermined values of voltage, pulse-on time, pulse-off time, and anodic gear reciprocating speed. The amount of tip relief is found to increase considerably with modification duration and electrolyte concentration. Identified optimum values of modification duration, cathode gear rotational speed, concentration, flow rate, and electrolyte temperature are 20 minutes, 45 rpm, 2 Molarity, 30 lpm, and 40°C, respectively. Scanning electron microscopy images of the tip-relieved spur gear revealed that PECFM effectively eliminates the hob cutter marks from its flank surfaces. This work will be helpful to gear manufacturers seeking productive tip relieving. [ABSTRACT FROM AUTHOR]

Background: Recent innovations, such as hydrosurgery, ultrasound therapy, and plasma-mediated bipolar radio-frequency ablation therapy could represent an alternative to conventional debridement in many cases, especially for chronic nonhealing wounds. Pulsed electromagnetic field (PEMF) has been used clinically as an intervention to enhance healing of chronic infected wound. The aim is to evaluate the effect of PEMF therapy on healing of chronic wounds, as regard timing and quality of healing. Methods: Fifty cases with chronic wounds, according to inclusion and exclusion criteria, the patient's age ranged from 20 -70 years, from outpatient clinic of military or transferred through civilian outpatient's clinic in different hospitals and specific diabetic foot centers. They are diagnosed as infected resistant chronic wounds depending on clinical, laboratory and radiological investigations due to various reasons will be managed by PEMF therapy. Results: There were statistically significant associations between treatment outcomes and pain (p =0.018), edema (p =0.005), number of sessions (p <0.001), microbial eradication (p =0.008). On the other hand, we found that there were statistically significant associations between complication rates and treatment outcome (p=0.008), microbial eradication (p <0.001), and hospital stay (p =0.002). Conclusion: the PEMF therapy is a safe and effective treatment option for patients with chronic, resistant, wounds. The current study shows that the PEFM achieved a high success rate. In addition, our analysis showed that achieving complete closure of the wound can be associated with significant symptomatic relief and few incidences of complications. Nevertheless, further studies are still needed to confirm our findings. [ABSTRACT FROM AUTHOR]

Pulsed plasma thrusters (PPT) have demonstrated enormous potential since the 1960s. One major shortcoming is their low thrust efficiency, typically <30%. Most of these losses are due to joule heating, while some can be attributed to poor efficiency of the power processing units (PPUs). We model PPTs to improve their efficiency, by exploring the use of power electronic topologies to enhance the power conversion efficiency from the DC source to the thruster head. Different control approaches are considered, starting off with the basic approach of a fixed frequency flyback converter. Then, the more advanced critical conduction mode (CrCM) flyback, as well as other optimized solutions using commercial off-the-shelf (COTS) components, are presented. Variations of these flyback converters are studied under different control regimes, such as zero voltage switching (ZVS), valley voltage switching (VVS), and hard switched, to enhance the performance and efficiency of the PPU. We compare the max voltage, charge time, and the overall power conversion efficiency for different operating regimes. Our analytical results show that a more dynamic control regime can result in fewer losses and enhanced performance, offering an improved power conversion efficiency for PPUs used with PPTs. An efficiency of 86% was achieved using the variable frequency approach. This work has narrowed the possible PPU options through analytical analysis and has therefore identified a strategic approach for future investigations. In addition, a new low-power coaxial micro-thruster model using equivalent circuit model elements is developed.This is referred to as the Carlow–Stuttgart model and has been validated against experimental data from vacuum chamber tests in Stuttgart's Pulsed Plasma Laboratory. This work serves as a valuable precursor towards the implementation of highly optimized PPU designs for efficient PPT thrusters for the next PETRUS (pulsed electrothermal thruster for the University of Stuttgart) missions. [ABSTRACT FROM AUTHOR]

A detailed study of the pulsed triple-wire gas indirect arc (TW-GIA) welding process based on the arc deflection effect was carried out in this article. The arc anode deflection mechanism, the effect of pulse parameters on weld forming and efficient welding process were systematically studied. The results showed that the special annular electric field and the non-uniform magnetic field were the main reasons for the indirect arc deflection to the anode. When the main wire acted as the anode and the side wires acted as the cathode, the two indirect arcs would deflect synchronously toward the main wire and couple into one arc with high energy density and larger arc stiffness. The arc length and welding depth can be controlled by adjusting the pulse parameters. A stable and efficient single-pass pulsed TW-GIA welding process for a 10 mm Q235 steel plate was developed. The fusion of the side wall of the welded joint was very good, the average tensile strength reached 471.2 Mpa and all joints broke in the base metal. [ABSTRACT FROM AUTHOR]

BACKGROUND:Various methods for peripheral nerve and epidural catheter location assessment exist, with varying degrees of ease of use, utility, and accuracy. Pulsed wave Doppler (PWD) evaluates the presence of fluid flow and is possible modality to assess the location of a percutaneously inserted perineural catheter. METHODS:A retrospective chart review was conducted in which PWD ultrasonography was used to confirm the position of nerve catheters for regional anesthesia. Data was collected to assess 24-hour postoperative pain scores, opioid consumption, complications, and the incidence of catheter replacement. RESULTS:Eighty-six patients were included; average age was 58 years and a 27% incidence of chronic pain. These catheters were left in place based on the PWD images. Three catheters failed and a total of 16 catheters were repositioned. In the first 24 hours average pain scores ranges between 3.5 to 5.9 and median postoperative opioid consumption range was 11.3 mg to 60.8 mg. For epidural catheters, PWD changes were more obvious with air injection and there was only one episode of hemodynamic instability. CONCLUSIONS:Our preliminary experience with PWD ultrasonography suggests that they may offer the ability to selectively assess flow at different locations to identify the proper location of epidural and perineural catheters. Future randomized, controlled investigations are warranted to further evaluate the effectiveness and safety of this modality.

Objective: To assess the effectiveness and safety of combined pulsed-dye laser (PDL) and NAFL for treatment of surgical scars. Summary Background Data: PDL and NAFL have not been compared to healing by time alone. Methods: Randomized controlled, single-blinded clinical trial at an urban, university hospital. Healthy adults' status post skin surgery with primary closure were randomized to either 3 sessions of combination PDL and NAFL every 2 to 8 weeks, or control of no treatment. At baseline and 36-week follow-up, Patient and observer Scar Assessment Scale and Scar Cosmesis Assessment and Rating were completed by participants and blinded physicians. The primary outcome was scar improvement, as measured by the score difference over time. Results: Of 76 participants, 52 completed the study (July 2017 to June 2019). No severe adverse events were reported. Patient and observer Scar Assessment Scale assessments demonstrated improvement in total score in the laser group compared to controls, as reported by patients [mean difference (standard deviation), laser: 12.86 (6.91) vs control: 7.25 (6.34); P = 0.004] and blinded physicians [18.32 (8.69) vs 13.08 (9.63); P = 0.044]. Patients observed a greater improvement in scar thickness [3.68 (2.04) vs 1.88 (1.85); P = 0.002] and stiffness [3.57 (2.78) vs 1.50 (2.11); P = 0.004] with lasers, and physicians reported greater improvement in vascularity [3.71 (1.98) vs 1.71 (1.52); P = 0.0002]. The live Scar Cosmesis Assessment and Rating subscore for erythema improved significantly with lasers [1.04 (0.79) vs 0.42 (0.50); P = 0.001]. Conclusions and Relevance: Combined PDL and NAFL resulted in scar improvement. Scar thickness, stiffness, and erythema were improved. Trial Registration: ClinicalTrials.gov (NCT03057964). [ABSTRACT FROM AUTHOR]

PURPOSE: To compare efficacy and safety between the two modes of energy delivery-pulsed and continuous, in accelerated corneal collagen cross-linking (KXL) to stop the keratoconus advancement through topographical, visual, and refractive endpoints. METHODS: It was a prospective, comparative, randomized, interventional trial. Patients with bilateral progressive keratoconus were subjected to pulsed mode KXL (P-KXL) in the right and continuous mode KXL (C-KXL) treatment in the left eye. In both methods, additional supplemental oxygen was delivered to corneal surface using a nasal cannula connected to an oxygen supply. Uncorrected distance visual acuity (UDVA) and corrected distance visual acuity, posttreatment manifest spherical equivalent and astigmatism, and corneal topography were studied. The deformation amplitude index (DAI) was measured by Corvis-ST. Postoperative follow-up was done. RESULTS: One hundred eyes of 50 patients underwent P-KXL in the right eye and C-KXL in the left eye. The average follow-up was 12.1 ± 1.2 months. At 1 year posttreatment, the UDVA had a mean change of 0.11 ± 0.14 logMAR in P-KXL and 0.18 ± 0.14 logMAR in C-KXL groups. The line of demarcation was observed at 251.13 ± 18.28 μ and 245.28 ± 28.26 μ deep, respectively, in P-KXL- and C-KXL-treated eyes at 6 months' follow-up. The DAI as measured by Corvis-ST showed a significant decrease from pretreatment values of 1.12 ± 0.13 mm to 0.84 ± 0.14 mm (P < 0.01) in P-KXL eyes and from 1.04 ± 0.14 mm to 0.85 ± 0.15 mm (P = 0.03) in C-KXL eyes. Both the groups did not show any statistically significant endothelial cell loss posttreatment. CONCLUSION: C-KXL can give similar functional outcomes as P-KXL with the help of supplemental oxygen delivery with the added advantage of a shortened procedure time in comparison to pulsed mode. [ABSTRACT FROM AUTHOR]

This article presents a pulsed-coherent lidar that uses a 19-GHz pulse-modulated optical carrier and segmented time-of-flight (ToF) detection. The receiver analog frontend (AFE) employs a down-conversion chain that consists of a phase-invariant programmable-gain low-noise amplifier (PI-PGLNA), a sub-harmonic mixer (SHM), and an inverter-based phase-invariant programmable-gain amplifier (PI-PGA). The local oscillator (LO) is generated from a phase-locked loop (PLL) with a ring-type voltage-controlled oscillator (VCO). An analog-to-digital converter (ADC) subsamples the down-converted signal, and a digital signal processor (DSP) calculates the coarse, intermediate, and fine ToF. At the receiver input, a narrowband matching is implemented between the p-i-n photodiode and the PI-PGLNA with direct wire bonding. The system achieves 6- $\mu \text{m}$ precision with a 5-MSa/s sampling rate at a 2.5-m distance. The 2-D scanning is achieved with this lidar with the use of an MEMS mirror. [ABSTRACT FROM AUTHOR]

The doppler-guided transanal hemorrhoidal dearterialization technique associated with mucopexy is a noninvasive surgical option used to treat hemorrhoidal disease (HD). Objective To compare and analyze the results using a variation of the doppler-guided transanal hemorrhoidal dearterialization technique with the technique of selective hemorrhoidal dearterialization with high mucopexy in the treatment of HD. Method A total of 292 patients who underwent surgical treatment for grade II, III and IV HD from March 2012 to December 2017 were studied. From this total, 110 (37.6%) patients underwent a conventional doppler-guided transanal hemorrhoidal dearterialization with mucopexy (CD), and 182 (62.3%) underwent selective hemorrhoidal dearterialization with high mucopexy (SHeLF). In the group of patients undergoing CD, 4 patients (3.64%) had grade II HD, 82 (74.55%) grade III, and 24 (21.82%) grade IV. In the group submitted to SHeLF, 18 (9.89%) patients had grade II HD, 86 (47.25%) had grade III, and 65 (35.71%) had grade IV. The same surgeon operated all patients under spinal anesthesia. In patients undergoing CD, six arterial branches have been dearterialized, while in patients undergoing SHeLF, the hemorrhoidary nipples submitted to a dearterialization were selected (from 1 to 5) by intraoperative evaluation followed by high rectal mucopexy. In the postoperative period, the following parameters were evaluated: pain, tenesmus, bleeding, and recurrence. Moderate results to severe pain was a postoperative complaint reported by 13 (11.82%) patients undergoing CD, and by 19 (10.44%) undergoing SHeLF. Intense tenesmus was reported by 26 (23.64%) patients undergoing CD and by 7 (3.85%) undergoing SHeLF. Three patients (2.73%) undergoing CD and 1 (0.55%) undergoing SHeLF evolved with postoperative bleeding. One patient (0.55%) in the group undergoing CD required surgical review of hemostasis. Six patients (5.45%) who underwent CD and 8 (4.39%) who underwent SHeLF were reoperated due to disease recurrence. Conclusion Comparing statistics, patients undergoing the SHeLF technique have less postoperative pain, tenesmus and postoperative bleeding when compared with CD.

Pulsed plasma thrusters (PPT) have demonstrated enormous potential since the 1960s. One major shortcoming is their low thrust efficiency, typically

Left ventricular (LV) dysfunction after orthotopic heart transplantation (OHT) is multifactorial and can be an indicator of graft rejection or coronary artery vasculopathy. Analysis of rotational mechanics may help in the early diagnosis of ventricular dysfunction. Studies describing the left ventricular rotational strain in children after OHT are lacking. It is important to establish the baseline rotational mechanics in pediatric OHT to pursue further studies in this population. Rotational strain measured by speckle tracking was compared in 32 children after OHT, with no evidence of active rejection or coronary artery vasculopathy with 35 age-matched normal controls. Twelve OHT patients and 13 controls underwent moderate exercise with pre- and postexercise echocardiography. Torsion, slope of the systolic limb of the torsion-radial displacement loop, and the untwist rate were significantly higher in OHT patients (torsion: median 2.7°/cm [Q1-Q3, 2.3-3.2] versus 2.3°/cm [Q1-Q3, 1.9-2.7]; P=0.03, torsion-radial displacement loop: 2.7°/mm [Q1-Q3, 2.1-3.6] versus 2.0°/mm [Q1-Q3, 1.6-2.7]; P=0.008, indexed peak untwist rate: -21.6°/s/cm [Q1-Q3, -24.3 to -15.7] versus -17.1°/s/cm [Q1-Q3, -19.6 to -13.3]; P=0.01). Contrary to controls, OHT recipients were unable to increase torsion with exercise (OHT: 2.8°/cm [2.7-3.2] versus 3°/cm [2.4-3.5]; P=0.81, controls: 2.2°/cm [2-2.6] versus 3°/cm [2.4-3.7]; P=0.01, pre and post exercise, respectively). The systolic slope of the torsion-radial displacement loop relationship decreased with exercise in most OHT patients. Baseline rotational strain in OHT patients is higher than normal with a blunted response to exercise. The slope of torsion-radial displacement loop, and its response to exercise, may serve as a marker of left ventricular dysfunction in OHT patients.

High-power solid-state lasers are among the hot research directions at the forefront of laser research and have major applications in industrial processing, laser-confined nuclear fusion, and high-energy particle sources. In this paper, the properties of Yb:YAG and Nd:YAG crystals as gain media for high-power solid-state lasers were briefly compared, according to the results of which Yb:YAG crystals are more suitable for high-power applications. Then, the effects of the thermodynamic and spectral properties of Yb:YAG crystals with temperature were analyzed in detail, and it was shown that the laser beams amplified by the cryogenically cooled Yb:YAG crystals could have higher beam quality, higher pump absorption efficiency, lower pump threshold, and higher gain. The change in properties of Yb:YAG crystal at low temperature makes it more suitable as a gain medium for high-power lasers. Subsequently, two types of kilowatt-class lasers using cryogenically cooled Yb:YAG crystals as gain media are introduced—100 J, 10 Hz nanosecond lasers and 1 J, 1 kHz picosecond lasers. Their configuration, main parameters, and typical output results were analyzed. Finally, future directions in the development of cryogenically cooled Yb:YAG lasers are discussed. [ABSTRACT FROM AUTHOR]

Simple Summary: Pulsed electromagnetic fields (PEMFs) are a type of biophysical stimulation that has been shown to be effective in improving bone regeneration and preventing bone loss. Their use dates back to the 1970s, but a gold standard treatment protocol has not yet been defined. PEMF efficacy relies on the generation of biopotentials, which activate several molecular pathways. There is currently no clear understanding of the effects on bone healing and, in addition, there are several animal models relevant to this issue. Therefore, drawing guidelines and conclusions from the analysis of the studies is difficult. In vivo investigations on PEMF stimulation are reviewed in this paper, focusing on molecular and morphological improvements in bone. Currently, there is little knowledge about the biological mechanism of PEMF and its effect on bone healing. This is due to the variability of crucial characteristics of electro-magnetic fields, such as amplitude and exposure frequency, which may influence the type of biological response. Furthermore, a different responsiveness of cells involved in the bone healing process is documented. Heterogeneous setting parameters and different outcome measures are considered in various animal models. Therefore, achieving comparable results is difficult. Biophysical energies are a versatile tool to stimulate tissues by generating biopotentials. In particular, pulsed electromagnetic field (PEMF) stimulation has intrigued researchers since the 1970s. To date, many investigations have been carried out in vivo, but a gold standard treatment protocol has not yet been defined. The main obstacles are represented by the complex setting of PEMF characteristics, the variety of animal models (including direct and indirect bone damage) and the lack of a complete understanding of the molecular pathways involved. In the present review the main studies about PEMF stimulation in animal models with bone impairment were reviewed. PEMF signal characteristics were investigated, as well as their effect on molecular pathways and osseous morphological features. We believe that this review might be a useful starting point for a prospective study in a clinical setting. Consistent evidence from the literature suggests a potential beneficial role of PEMF in clinical practice. Nevertheless, the wide variability of selected parameters (frequency, duration, and amplitude) and the heterogeneity of applied protocols make it difficult to draw certain conclusions about PEMF effectiveness in clinical implementation to promote bone healing. Deepening the knowledge regarding the most consistent results reported in literature to date, we believe that this review may be a useful starting point to propose standardized experimental guidelines. This might provide a solid base for further controlled trials, to investigate PEMF efficacy in bone damage conditions during routine clinical practice. [ABSTRACT FROM AUTHOR]

ObjectivesOptimal perinatal management of total anomalous pulmonary venous return (TAPVR) involves timely identification followed by surgical correction. Antenatal diagnosis, however, has long been a challenge. We aimed to identify consistent prenatal sonographic features in this condition in a large cohort in whom the diagnosis was made antenatally and confirmed postnatally.MethodsWe conducted a systematic retrospective review of the 2-dimensional and Doppler sonographic features that had helped make the diagnosis of TAPVR at our institution from 2001 to 2012.ResultsTwenty-six patients had prenatal diagnosis of TAPVR (mean gestational age, 24.1 weeks). Four of the fetuses with a prenatal diagnosis represented isolated cases of TAPVR; 22 had heterotaxy syndrome, additional cardiac abnormalities, or both. Prenatally diagnosed abnormal pulmonary venous connections were supracardiac (type I) in 18 cases, cardiac (type II) in 1, and infradiaphragmatic (type III) in 7. Lack of a visible connection of the pulmonary veins to the atrium (100%) and the presence of a visible venous confluence on axial 4-chamber views (96%) were the most consistent findings. Cardiac asymmetry and the presence of additional vertical venous channels on 3-vessel or axial abdominal views were also noted but less consistently. Abnormal pulmonary venous spectral Doppler findings were present in 25 of the 26 fetuses.ConclusionsThe diagnosis of TAPVR can be suspected on standard axial views included in second-trimester obstetric screening examinations of the fetal heart and confirmed on fetal echocardiography with the use of pulsed wave Doppler imaging. Clues recognizable on obstetric sonographic screening have the potential to contribute to increasing the diagnostic yield for prenatal detection of TAPVR.

ObjectivesFetuses with pulmonary outflow tract obstruction (POTO) have altered blood flow to the pulmonary vasculature. We sought to determine whether pulmonary vascular impedance, as assessed by the pulsatility index (PI), is different in fetuses with POTO compared with normal controls.MethodsBranch pulmonary artery PI was evaluated in age-matched normal control fetuses (n=22) and 20 POTO fetuses (pulmonary stenosis n=15, pulmonary atresia n=5). Pulsed-wave Doppler was performed in the proximal (PA1), mid (PA2) and distal (PA3) branch pulmonary artery. The direction of flow in the ductus arteriosus was noted. The study and control groups were compared with Student's t-test and ANOVA. A linear mixed model evaluated the relationship between PI and ductus arteriosus flow patterns.ResultsThere was no difference in PI between control, pulmonary stenosis and pulmonary atresia subjects at PA1 and PA2; however, there was a significant difference at PA3. Subjects with pulmonary atresia had a lower PI at PA3 than did controls (P=0.003) and pulmonary stenosis subjects (P=0.003). Subjects with retrograde flow in the ductus arteriosus had lower PIs in PA2 and PA3 than did those with antegrade flow (P=0.01 and 0.005, respectively). The PI in PA3 was lower in fetuses that required prostaglandin postnatally than in those that did not (P=0.008).ConclusionsFetuses with pulmonary atresia or severe pulmonary stenosis with retrograde flow in the ductus arteriosus have decreased PI in the distal pulmonary vasculature. Our findings indicate the capacity of the fetal pulmonary vasculature to vasodilate in response to anatomical obstruction of flow.

ObjectiveTo determine the association of arterial stiffness and pressure pulsatility, which can damage small vessels in the brain, with vascular and Alzheimer-type brain aging.MethodsStroke- and dementia-free Framingham Offspring Study participants (n = 1,587, 61 ± 9 years, 45% male) underwent study of tonometric arterial stiffness and endothelial function (1998-2001) and brain MRI and cognition (1999-2002). We related carotid-femoral pulse wave velocity (CFPWV), mean arterial and central pulse pressure, and endothelial function to vascular brain aging by MRI (total cerebral brain volume [TCBV], white matter hyperintensity volume, silent cerebral infarcts) and vascular and Alzheimer-type cognitive aging (Trails B minus Trails A and logical memory-delayed recall, respectively).ResultsHigher CFPWV was associated with lower TCBV, greater white matter hyperintensity volume, and greater prevalence of silent cerebral infarcts (all p < 0.05). Each SD greater CFPWV was associated with lower TCBV equivalent to 1.2 years of brain aging. Mean arterial and central pulse pressure were associated with greater white matter hyperintensity volume (p = 0.005) and lower TCBV (p = 0.02), respectively, and worse verbal memory (both p < 0.05). Associations of tonometry variables with TCBV and white matter hyperintensity volume were stronger among those aged 65 years and older vs those younger than 65 years (p < 0.10 for interaction). Brachial artery endothelial function was unrelated to MRI measures (all p > 0.05).ConclusionsGreater arterial stiffness and pressure pulsatility are associated with brain aging, MRI vascular insults, and memory deficits typically seen in Alzheimer dementia. Future investigations are warranted to evaluate the potential impact of prevention and treatment of unfavorable arterial hemodynamics on neurocognitive outcomes.

BackgroundThe aim of this study was to compare the reproducibility, agreement, and sensitivity of pulsed-wave Doppler tissue imaging (DTI) versus spectral Doppler assessment of right ventricular (RV) myocardial performance index (MPI) in midgestation fetuses in both a normal and a disease state.MethodsRV MPI was calculated using pulsed-wave DTI and spectral Doppler in normal pregnancies (n = 69) and in women with pregestational diabetes (n = 51). Intraobserver and interobserver variability and agreement were evaluated using Bland-Altman analysis. Student's t tests were used for comparisons of differences.ResultsIn normal fetuses, RV MPI derived by the two methods showed no statistical difference, were interchangeable (DTI, 0.51 ± 0.10; spectral Doppler, 0.50 ± 0.12; P = .686), and were in agreement by Bland-Altman analysis. However, in fetuses of mothers with diabetes, the two methods produced different RV MPI measurements (DTI, 0.56 ± 0.10; spectral Doppler, 0.51 ± 0.12; P < .001). Intraobserver and interobserver bias was lower for DTI.ConclusionsThe DTI method of measuring fetal RV MPI is more sensitive, has less variability and more precision, and is better able to demonstrate subtle abnormalities in cardiac function than the spectral Doppler method in diabetic versus normal pregnancies.

This study analyzed the average temperature value of the metallic droplets and weldpool of the Pulsed GMAW welding process using 309L-Si electrode as the addition metal. The study was based on the formulation and evaluation of pulsed waves, starting from the equation of energy constant (or detachment constant), and waveforms from two commercial welding sources, that were evaluated and reproduced. The technique of filming by high speed infrared radiation was used for evaluation. The results point to a higher droplet temperature for a lower intensity of pulse current, due to longer dwell time at this level, and also revealing that a longer time in the base phase may be responsible for a further heating of the fusion pool.

High-power solid-state lasers are among the hot research directions at the forefront of laser research and have major applications in industrial processing, laser-confined nuclear fusion, and high-energy particle sources. In this paper, the properties of Yb:YAG and Nd:YAG crystals as gain media for high-power solid-state lasers were briefly compared, according to the results of which Yb:YAG crystals are more suitable for high-power applications. Then, the effects of the thermodynamic and spectral properties of Yb:YAG crystals with temperature were analyzed in detail, and it was shown that the laser beams amplified by the cryogenically cooled Yb:YAG crystals could have higher beam quality, higher pump absorption efficiency, lower pump threshold, and higher gain. The change in properties of Yb:YAG crystal at low temperature makes it more suitable as a gain medium for high-power lasers. Subsequently, two types of kilowatt-class lasers using cryogenically cooled Yb:YAG crystals as gain media are introduced—100 J, 10 Hz nanosecond lasers and 1 J, 1 kHz picosecond lasers. Their configuration, main parameters, and typical output results were analyzed. Finally, future directions in the development of cryogenically cooled Yb:YAG lasers are discussed.

High performance solar collectors are those with high selectivity surfaces, high solar radiation absorption and that do not thermally reemit to the external environment. Strategies to enhance this performance might involve surface porosity modification. In this work, a plasma treatment technique called plasma electrolytic oxidation (PEO) has been tested to produce porosity on aluminium surfaces in a controlled manner. The porosity control was made by varying the intensity, frequency and duty cycle of the applied voltage pulses. The aluminium sample was placed in a solution of 1 g/L Na2SiO3. Voltage of 500 V and current density of 0.17 A cm2 was applied between electrodes. Three duty cycles were used: 33.33%, 50.00% and 67.77%. After treatment, the size, number and distribution of pores were evaluated. These parameters were correlated with both surface reflectance and optical absorbance. It was possible to control the porosity by controlling the electrical parameters of the process. While the mean pore size was directly related to the duty cycle, the inverse occurred for the number of pores. Surface treated with duty cycle of 33.33% presented higher values of absorption for all wavelength range.

Background This study prospectively compared intraoperative pain scores during percutaneous microwave ablation of the liver in patients randomized between continuous and pulsed energy delivery algorithms. Methods During a 12-month period, 20 patients who underwent microwave liver ablation were prospectively randomized between 2 different energy delivery modes: “continuous mode” (CM, n=10) and “pulsed mode” (PM, n=10). All ablation sessions were performed using the same microwave ablation platform under computed tomographic guidance and intravenous analgesia. Within 30 min post ablation, all patients completed a questionnaire assigning a numeric pain intensity score from 0 (no pain) to 10. Results Mean pain scores were 8.17±1.850 in the CM group and 4.50±1.567 in the PM group, with a statistically significant difference of 3.667±2.807 pain units (P=0.001). The mean procedure time was 53.5±20.90 min in the PM group vs. 58.5±17.44 min in the CM group (P=0.279). The mean size of the lesions was 2.81±0.95 cm in the PM group and 2.81±0.85 cm in the CM group (P=0.984). On a per-lesion basis, technical success was achieved in all evaluable tumors in both groups. No difference was noted in the local tumor control on the 6-month imaging evaluation. No complications were observed in the CM arm, while small perihepatic hemorrhagic fluid collections were reported in the PM group. Conclusions Both algorithms for microwave energy delivery have comparable treatment effects in terms of 6-month local tumor control for liver lesions <3 cm in diameter. PM treatments compared to CM appear to induce significantly less pain in patients undergoing percutaneous liver ablation under intravenous analgesia. [ABSTRACT FROM AUTHOR]

Objectives: Ductus venosus (DV) Doppler examinations in pregnancy have a widespread use for several important indications and play a crucial role in order to determine the fetal well-being. DV is usually visualized by the color Doppler mapping. We observed the instantaneous spectral flow type changes in pulsed Doppler examinations in spite of performing with the correct technique published by several authors. The variability of the pattern makes the sonographer/physician to be unsure for the correct placements of the sample gate despite fulfilling the all the criteria required for the vessel sampling. It is aimed in the study to define variations of the normal DV spectral flow types in the duration of the pulsed Doppler examinations instead of in a single cardiac cycle in normal pregnancies. Methods: This prospective study was conducted between January 2016 and February 2017. Wide-band Doppler technique was used for color mapping of the DV. Normal spectral Doppler waveforms in pregnancies are classified as types. When DV spectral flow pattern was not in the standard type, the spectral flow patterns were obtained from not only the umbilical artery and/or middle cerebral artery. Maximum and minimum blood flow velocities in the umbilical vein are measured. All Doppler examinations are performed by a single experienced specialist (CG), who had been certificated for DV flow and Doppler examinations by the Fetal Medicine Foundation. Results: A total of seven types of flow patterns were recorded during the study period and DV flow patterns were divided into two main categories as classic flow pattern and the other patterns. The classic pattern was observed in 160 (99.4%) cases in the first trimester, 495 (94.1%) cases in the second trimester and 206 (60.8%) cases in the third trimester. Conclusions: We think that the fetal circulation is complicated more than estimated. There might be some endocrine agents released in the instantaneous physiologic reactions and changing the venous return abruptly or due to decreasing of the cardiac output directed to the placenta after 34 weeks influence the volume of the circulating blood in the fetus and so thereby the flow velocities instantaneously. The spectral waveform recognition approach is not reliable to identify if the DV spectral Doppler pattern is not the classic (standard) type and the DV should be visualized by wide-band color Doppler techniques particularly in the third trimester for the pulsed Doppler examinations. Studies are needed to evaluate the normal spectral variants of the flows correlated with the physiological compensatory mechanisms. [ABSTRACT FROM AUTHOR]

Objective: To further evaluate the efficacy and safety of computerized tomography–guided sphenopalatine ganglion–targeted pulsed radiofrequency treatment for patients with refractory episodic and chronic cluster headache (CH). Methods: Forty‐five patients with refractory episodic CH and 14 patients with chronic CH who underwent computerized tomography–guided sphenopalatine ganglion–targeted pulsed radiofrequency between January 2011 and December 2018 at the Beijing Tiantan Hospital were included and analyzed in this retrospective cohort study. Results: A total of 59 patients underwent 106 computerized tomography–guided pulsed radiofrequency procedures throughout the observational period. Effective remission was observed in 95.6% and 64.3% of patients with refractory episodic and chronic CH, respectively. Repeated computerized tomography–guided sphenopalatine ganglion–targeted pulsed radiofrequency procedures for recurrent CH was also proven to be effective. No severe side effects or complications were observed in this study. Conclusion: The computerized tomography–guided sphenopalatine ganglion–targeted pulsed radiofrequency procedure is an effective, safe, and repeatedly effective strategy for refractory CH. For patients who have not responded to conservative treatment, this minimally invasive intervention is a reliable alternative. [ABSTRACT FROM AUTHOR]

This paper presents a systematic investigation on the growth of TiO2 nanotubes (NTs) by modifying the continuity in the applied potential through conventional one-step electrochemical anodization (CEA), paused electrochemical anodization (PEA), two-step electrochemical anodization (TEA), and pulsed electrochemical anodization (PLA). The essence of this research pertains to understanding the significance of surface solid fraction factor (ψ) in relation to the density of surface defects. Additionally, in order to comprehend and incorporate the influence of cracks on surface defects and carrier transport, the reported ψ has been modified for the first time. Moreover, this attempt involves the use of H2O2 as an electrolytic oxidizer for the first time in PEA, TEA, and PLA techniques to explore the possibility in creating ripple free NTs. UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), photoluminescence, and X-ray photoelectron spectroscopy (XPS) provided insights into the band gap and quantification of surface defects for NTs anodized via continuous and pulsed modes. The effect of voltage continuity on % porosity of the TiO2 NT arrays was investigated. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques were also carried out to determine the electrical properties of the prepared TiO2 NT arrays. [ABSTRACT FROM AUTHOR]

The ramjets of different schemes with slow and detonation combustion are compared. Steady and unsteady processes in these engines are described by simple models of gasdynamics and thermodynamics, detonation waves, air deceleration in air intakes, and combustion product acceleration in supersonic sections of nozzles. Within the framework of these models, at a fixed adiabatic exponent the characteristics of any engine depend on two parameters, namely, the flight Mach number and the dimensionless combustion heat of the combustible mixture. The comparison performed for all actual values of these parameters, together with an analysis of thermodynamic cycles and one-dimensional time-dependent calculations (for the engines with combustion in traveling detonation waves), confirmed the importance of taking the unsteady processes in combustors into account. The comparison made in this study is actual, due to frequent claims about a possible considerable increase in the thrust characteristics on replacement of ramjets with slow combustion under a constant pressure by engines with combustion in pulsed or rotating detonation waves (pulse-detonation engines (PDE) or rotating detonation engines (RDE)). Usually, these assertions are made on the basis of the comparison of the thermal efficiencies and specific thrusts and impulses calculated according to these values. In the case of unsteady flow in the combustor, the recalculation of the thrusts and impulses according to the thermal efficiency overestimates their values. The validity of this statement for multichambered PDEs is confirmed by time-dependent calculations. In the case of instantaneous opening and closing of the entrance into the detonation chambers and an instantaneous, without energy expenditures, detonation wave initiation, the PDE thrust is less than the ramjet thrust, starting from small supersonic flight Mach numbers. Analogous calculations for the RDEs are unjustified due to the passage into a rotating noninertial coordinate system. [ABSTRACT FROM AUTHOR]