In this work, we elaborated the graphite screen-printed electrodes (SPEs) modification with metal nanoparticles formed as a result of spark discharges produced between a metal wire electrode and SPE ...that are connected to an Arduino board-based DC high voltage power supply. This sparking device allows, on the one hand, the toposelective formation of NPs of controlled dimensions through a direct and liquid-free approach, and on the other hand, controls the number and energy of the discharges delivered to the electrode surface during a single spark event. This way, the potential damage to the SPE surface by the action of heat evolved during the sparking process is considerably minimized compared with the standard setup in which each spark event consists of multiple electrical discharges. Data demonstrated that the sensing properties of the resulting electrodes are significantly improved compared with those achieved when conventional spark generators are employed, as demonstrated for silver-sparked SPEs that exhibit enhanced sensitivity to riboflavin. Sparked AgNp-SPEs were characterized using scanning electron microscopy and voltammetric measurements in alkaline conditions. The analytical performance of sparked AgNP-SPEs was evaluated by various electrochemical techniques. Under optimum conditions, the detection range for DPV was from 1.9 (LOQ) to 100 nM riboflavin (R2 = 0.997), while a limit of detection (LOD, S/N 3) of 0.56 nM was achieved. The analytical utility is demonstrated for the determination of riboflavin in the real matrices of B-complex pharmaceutical preparation and an energy drink.
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•Modification of screen-printed electrodes (SPEs) using spark discharges.•Toposelective, size controlled NPs via number and energy of discharges per spark.•Minimal damage to SPE surface by heat evolved during the sparking.•Silver-sparked SPEs that exhibit enhanced sensitivity to riboflavin.•Riboflavin determination in real matrices (vitamin pill and energy drink.
This paper presents an improved positioning method for a Magnetic Encoder type Guided Vehicle (MEGV) using the Extended Kalman Filter and Encoder Compensation Method. The magnetic encoder system is ...one of several available guidance systems for autonomous guided vehicles using magnetic sticks that are buried at regular intervals (such as near landmarks, turning points, and work places) on designated paths. The system guides MEGVs on a pre-defined path using either of two types of devices: encoders or magnetic positioning devices. The encoder information is used in a range of positions between the magnetic sticks, and the magnetic positioning device is used to correct positioning of MEGV using global positioning of a magnetic stick. However, calculating the exact position of a MEGV is challenging because of errors (cumulative error of the encoder and disturbances in the general magnetic field). Therefore, this study proposes a method, which is a combination of EKF and ECM, for positioning MEGVs. In the proposed method, EKF first estimates the position of the MEGV; then, ECM corrects the error of the encoders. To analyze the performance of the proposed method, a MEGV was designed and developed. The proposed method was compared with three other positioning methods (that use encoders, magnetic encoders, or EKF), and experiments were performed under similar working conditions. The experimental results demonstrated that the proposed method is superior to the other methods.
Graphite screen-printed electrodes (SPEs) were modified with gold nanoparticles (AuNPs) produced by electric spark discharge between the SPE and a gold-silicon eutectic alloy (eAu/Si) tip electrode, ...under atmospheric conditions at 1.2 kV DC using a fully automated procedure. The automation was based on a 3D positioning device, which allowed to precisely adjust the sparking distance and to achieve regular spacing of a predetermined number of sparks across the surface of SPEs (d = 3 mm) by controlling the movement of the eAu/Si tip. Moreover, the effect of voltage-time characteristics of the produced discharges on the morphological and electroanalytical properties of the sparked-modified SPEs was investigated by setting the values of capacitors in the high voltage multiplier cascade, and at the power supply output. It is shown that under specific variables the underlying carbon layer is not appreciably damaged by the spark discharges and does not contribute to electrochemical responses of sparked SPEs, i.e., the active electrode surface has been entirely covered by AuNPs. Sparked surfaces were extensively characterized by scanning electron microscopy and various electrochemical techniques, while the electroanalytical utility of eAu/Si-sparked SPE was investigated with ascorbic acid as a pilot analyte. Advanced electrocatalytic activity is documented by an extreme shift of ascorbate oxidation overpotential (Ep = 89 mV at eAu/Si-sparked SPE) with respect to both bare SPE (Ep = 503 mV) and bulk gold electrode (Ep = 358 mV). Simultaneous differential pulse voltammetric sensing of ascorbic and uric acids in human urine is also demonstrated.
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•Highly reactive “naked” spark discharge produced gold nanoparticles.•Extended coverage of SPEs by sparked AuNPs (sAu-SPE) with a 3D positioning device.•At sAu-SPE the response of the graphitic underlying substrate is suppressed.•Assessment of sparking voltage-time characteristics to develop advanced sensors.•Simultaneous DPV sensing of ascorbic and uric acids in human urine.
Volumetric Modulated Arc Therapy (VMAT) techniques have recently been implemented in clinical practice for total-body irradiation (TBI). To date, most techniques still use special couches, ...translational tables, or other self-made immobilization devices for dose delivery. Aim of the present study was to report the first results of a newly developed rotatable tabletop designed for VMAT-TBI.
The VMAT-TBI technique theoretically allows the use of any standard positioning device at the linear accelerator. Nevertheless, the main problem is that patients taller than 120 cm cannot be treated in one position due to the limited cranial-caudal couch shift capacities of the linac. Therefore, patients are usually turned from a head-first supine position (HFS) to a feet-first supine position (FFS) to overcome this limitation. The newly developed rotatable tabletop consists completely of carbon fiber, including the ball bearing within the base plate of the rotation unit. The patient can be turned 180° from a HFS to a FFS position within a few seconds, without the need of repositioning.
The first 20 patients had a median age of 47 years, and received TBI before bone marrow transplantation for acute myeloid leukemia. Most patients (13/20) received a TBI dose of 4 Gy in 2 fractions, twice daily. The mean number of applied monitor units (MU) was 6476 MU using a multi-arcs and multi-isocenter VMAT-TBI technique. The tabletop has been successfully used in daily clinical practice and helped to keep the treatment times at an acceptable level. During the first treatment fraction, the mean overall treatment time (OTT) was 57 min. Since no additional image guidance was used in fraction 2 of the same day, the OTT was reduced to mean 38 min.
The easy and reproducible rotation of the patient on the treatment couch using the rotatable tabletop, is time-efficient and overcomes the need of repositioning the patient after turning from a HFS to a FFS position during VMAT TBI. Furthermore, it prevents couch-gantry collisions, incorrect isocenter shifts and beam mix-up due to predicted absolute table coordinates, which are recorded to the R + V system with the corresponding beams.
A new disposable percutaneous positioning device was developed which permits adjustment of the fixing puncture angle while performing a percutaneous core needle lung biopsy (CNLB). The aim of the ...study was to explore the positioning accuracy and clinical safety of the new device during CT-guided percutaneous CNLB.
A prospective, open and randomized controlled study with two parallel groups was conducted on 150 patients with pulmonary nodules between July 1, 2018 and June 30, 2019 including 101 males and 49 females who were divided (allocation ratio: 1:1) into a standard CNLB group without the percutaneous positioning device (control, n=75) and a new percutaneous positioning device group combined with CNLB (experimental, n=75). The efficacy was determined by the success rate of reaching the target location on the first percutaneous attempt, the number of CT scans performed and the time required for successful puncture positioning. Safety evaluations included complications related to percutaneous surgery and the new positioning device.
The success rate of reaching the target location on the first percutaneous attempt in the experimental group was significantly higher than in the control group 96.0% (72/75)
42.7% (32/75), P<0.001. Patients in the experimental group received 3.05±0.28 times CT scans on average for successful percutaneous positioning, which was significantly lower than for the control group (3.95±1.03) (P<0.001). The time required to complete the percutaneous positioning was significantly lower in the experimental group compared to the control group (8.73±3.11
12.79±4.55 min, P<0.001). There was no significant difference in percutaneous-related complications between the two groups 48.0% (36/75)
61.3% (46/75), P=0.101, except that the bleeding rate in the experimental group was lower than in the control group 26.7% (20/75)
46.7% (35/75), P=0.032.
The use of the optimized percutaneous technology with the new positioning device significantly improved the accuracy and precision of percutaneous lung biopsies.
ChiCTR-INR-17010322.
When three-dimensional positioning devices such as a robot arm are operated, it is desirable for the devices to be operated by humans without the need for prior practice. The operating method in ...which the operator moves his/her arm and the device performs the same motion is a possible method. However, a difference may exist between the intended arm motion of the operator and the actual motion. In such a case, the positioning device performs the unintended than the intended motion of the operator. Therefore, in this study, the difference between the intended arm motion of the operator and the actual motion was investigated experimentally, supposing that the operator operates the device by his/her arm motion. The experimental results revealed that the operator tends to move the wrist joint center along a curve even though he/she intends to move it linearly. As an example, if the operator intends to move the wrist position straight in the right and left directions or the up and down directions, the actual wrist position tends to move along a curved path convex to the far direction. By considering the observed difference between the intended arm motion and the actual motion, an operating method was established. This method uses conversion equations to calculate the intended arm motion of the operator from the measured data of actual arm motion. In another experiment, operations using the new conversion equations and the conventional operation method were carried out. The results were compared and the effectiveness of the proposed method was confirmed.
Cell transplant-mediated tissue repair of the damaged spinal cord is being tested in several clinical trials. The current candidates are neural stem cells, stromal cells, and autologous Schwann cells ...(aSC). Due to their peripheral origin and limited penetration of astrocytic regions, aSC are transplanted intralesionally as compared to neural stem cells that are transplanted into intact spinal cord. Injections into either location can cause iatrogenic injury, and thus technical precision is important in the therapeutic risk-benefit equation. In this chapter, we discuss how we bridged from transplant studies in large animals to human application for two Phase 1 aSC transplant studies, one subacute and one chronic. Preclinical SC transplant studies conducted at the University of Miami in 2009-2012 in rodents, minipigs, and primates supported a successful Investigational New Drug (IND) submission for a Phase 1 trial in subacute complete spinal cord injury (SCI). Our studies optimized the safety and efficiency of intralesional cell delivery for subacute human SCI and led to the development of new simpler techniques for cell delivery into subjects with chronic SCI. Key parameters of delivery methodology include precision localization of the injury site, stereotaxic devices to control needle trajectory, method of entry into the spinal cord, spinal cord motion reduction, the volume and density of the cell suspension, rate of delivery, and control of shear stresses on cells.
Low physical activity levels and high levels of sedentary time among adolescents call for population wide interventions. Public open spaces can be important locations for adolescents' physical ...activity. This study aimed to describe the prevalence, frequency and context of public open space visitation and to gain insight into the individual, social and physical environmental factors associated with public open space use among 12- to 16-year-old Flemish (Belgian) adolescents.
Global positioning system devices, accelerometers and one-on-one interviews were used to measure location-specific activity levels, time spent at, reasons for using and accompaniment at public open spaces among 173 adolescents. Multilevel hurdle and gamma models were used to estimate the associations between the independent variables (age, gender, ethnicity, education, sport club membership and accompaniment) and the amount of time, sedentary time, light-, moderate- to vigorous- and vigorous-intensity physical activity at public open spaces.
Three out of four participants had visited a public open space (for recreational purposes) and participants were most often accompanied by friends/classmates. Mainly public transportation stops/stations were used, and subsequently the most reported reason for public open space use was "to wait for something or someone". Furthermore, boys, younger adolescents, non-western-European adolescents and lower educated adolescents were more likely to use public open spaces. Additionally, boys and younger adolescents were more likely to accumulate physical activity at public open spaces. The only social environmental variable associated with time spent at public open spaces was accompaniment by siblings: adolescents spent more time at public open spaces when accompanied by their siblings.
Public open spaces may be effective areas to promote physical activity among groups at risk for physical inactivity (i.e. low educated and non-western-European adolescents). Additionally, girls and older adolescents were less likely to visit and be physically active at public open spaces. Therefore, urban planners should consider adding attractive features, in order to encourage physical activity among girls and older adolescents at public open spaces. Furthermore, creating public open spaces that are attractive for youth of all ages could contribute to adolescents visiting public open spaces accompanied by siblings.
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