Expression of concern: Investigation of the biological activity, mechanical properties and wound healing application of a novel scaffold based on lignin-agarose hydrogel and silk fibroin embedded zinc chromite nanoparticles.

Expression of concern for 'Investigation of the biological activity, mechanical properties and wound healing application of a novel scaffold based on lignin-agarose hydrogel and silk fibroin embedded zinc chromite nanoparticles' by Reza Eivazzadeh-Keihan et al., RSC Adv., 2021, 11, 17914-17923, https://doi.org/10.1039/D1RA01300A.

Radiation Impedance of Rectangular CMUTs.

Recently, capacitive micromachined ultrasound transducers (CMUTs) with long rectangular membranes have demonstrated performance advantages over conventional piezoelectric transducers; however, modeling these CMUT geometries has been limited to computationally burdensome numerical methods. Improved fast modeling methods, such as equivalent circuit models, could help achieve designs with even better performance. The primary obstacle in developing such methods is the lack of tractable methods for computing the radiation impedance of clamped rectangular radiators. This paper presents a method that approximates the velocity profile using a polynomial shape model to rapidly and accurately estimate radiation impedance. The validity of the approximate velocity profile and corresponding radiation impedance calculation was assessed using finite element simulations for a variety of membrane aspect ratios and bias voltages. Our method was evaluated for rectangular radiators with width:length ratios from 1:1 up to 1:25. At all aspect ratios, the radiation resistance was closely modeled. However, when calculating the radiation reactance, our initial approach was only accurate for low aspect ratios. This motivated us to consider an alternative shape model for high aspect ratios, which was more accurate when compared with FEM. To facilitate the development of future rectangular CMUTs, we provide a MATLAB script that quickly calculates radiation impedance using both methods.

Transparent Dual-Frequency CMUT Arrays for Photoacoustic Imaging.

The opaque ultrasound transducers used in conventional photoacoustic imaging systems necessitate oblique light delivery, which gives rise to some disadvantages such as inefficient target illumination and bulky system size. This work proposes a transparent capacitive micromachined ultrasound transducer (CMUT) linear array with dual-band operation for through-illumination photoacoustic imaging. Fabricated using an adhesive wafer bonding method, the array consists of optically transparent conductors [indium tin oxide (ITO)] as both top and bottom electrodes, a transparent polymer [bisbenzocyclobutene (BCB)] as the sidewall and adhesive material, and largely transparent silicon nitride as the membrane. The fabricated device had a maximum optical transparency of 76.8% in the visible range. Furthermore, to simultaneously maintain higher spatial resolution and deeper imaging depth, this dual-frequency array consists of low- and high-frequency channels with 4.2- and 9.3-MHz center frequencies, respectively, which are configured in an interlaced architecture to minimize the grating lobes in the receive point spread function (PSF). With a wider bandwidth compared to the single-frequency case, the fabricated transparent dual-frequency CMUT array was used in through-illumination photoacoustic imaging of wire targets demonstrating an improved spatial resolution and imaging depth.

The psychological symptoms and behavioral problems of children with mothers working as medical staff in the crisis of Covid-19 outbreak in Hamadan, Iran.

Background and objectives: The purpose of this study was to investigate the psychological symptoms and behavioral problems of children with mothers working as medical staff in the crisis of Covid-19 disease in Hamadan. Methods: This descriptive causal-comparative study was conducted on all mothers with children aged 6 to 12 years in Hamadan from September 2 to November 29, 2020. In this study, eligible individuals were selected using random sampling and were assigned to two groups of mothers working as the medical staff and the control group. The research instruments included the Child Behavior Checklist (Achenbach) and the Child Symptom Inventory-4 (CSI-4). Results: The results showed that the mean scores of psychological and behavioral symptoms of children in terms of group membership (group of mothers working in the medical staff and control group) had a significant difference. There was a significant difference between the mean scores of depression and aggression in children of the staff group and the control group meaning that for depression and aggression scores of children of the staff group are higher than children of the control group (p < 0.05). There was no significant difference between the mean anxiety scores and there was almost a significant difference between the attention scores of the staff group and the control group (p < 0.05). Conclusion: Children whose mothers worked as medical staff during Covid-19 show more depression, attention, and aggression problems than children whose mothers do not work as medical staff.

High-Voltage Bias-Switching Electronics for Volumetric Imaging using Electrostrictive Row-Column Arrays.

Top Orthogonal to Bottom Electrode (TOBE) arrays, also known as row-column arrays, hold great promise for fast high-quality volumetric imaging. Bias-voltage-sensitive TOBE arrays based on electrostrictive relaxors or micromachined ultrasound transducers can enable readout from every element of the array using only row and column addressing. However, these transducers require fast bias-switching electronics which are not part of a conventional ultrasound system and are non-trivial. Here we report on the first modular bias-switching electronics enabling transmit, receive, and biasing on every row and every column of TOBE arrays, supporting up to 1024 channels. We demonstrate the performance of these arrays by connection to a transducer testing interface board and demonstrate 3D structural imaging of tissue and 3D power Doppler imaging of phantoms with realtime B-scan imaging and reconstruction rates. Our developed electronics enable interfacing of bias-switchable TOBE arrays to channel-domain ultrasound platforms with software-defined reconstruction for next-generation 3D imaging at unprecedented scales and imaging rates.

Ultrafast Orthogonal Row-Column Electronic Scanning (uFORCES) With Bias-Switchable Top-Orthogonal-to-Bottom Electrode 2-D Arrays.

Top-orthogonal-to-bottom electrode (TOBE) arrays, also known as row-column arrays, have shown great promise as an alternative to fully wired 2-D arrays, owing to a considerable reduction in channels. Novel imaging schemes with bias-switchable TOBE arrays were previously shown to offer promise compared with previous nonbias-switchable row-column imaging schemes and compared with previously developed explososcan methods, however, they required significant coherent compounding. Here, we introduce ultrafast orthogonal row-column electronic scanning (uFORCES), an ultrafast coded synthetic aperture imaging method. Unlike its FORCES predecessor, uFORCES can achieve coherent compounding with only a few transmit events and may, thus, be more robust to tissue motion. We demonstrate through simulations that uFORCES can potentially offer improved resolution compared with the matrix probes having beamformers constrained by the paraxial approximation. Also, unlike current matrix probe technology incorporating microbeamforming, uFORCES with bias-switchable TOBE arrays can achieve ultrafast imaging at thousands of frames per second using only row and column addressing. We also demonstrate the experimental implementation of uFORCES using a fabricated 128 ×128 electrostrictive TOBE array on a crossed 25- [Formula: see text] gold wire phantom and a tissue-mimicking phantom. The potential for improved resolution and ultrafast imaging with uFORCES could enable new essential imaging capabilities for clinical and preclinical ultrasound.

Investigation of the biological activity, mechanical properties and wound healing application of a novel scaffold based on lignin-agarose hydrogel and silk fibroin embedded zinc chromite nanoparticles.

Given the important aspects of wound healing approaches, in this work, an innovative biocompatible nanobiocomposite scaffold was designed and prepared based on cross-linked lignin-agarose hydrogel, extracted silk fibroin solution, and zinc chromite (ZnCr2O4) nanoparticles. Considering the cell viability technique, red blood cell hemolysis in addition to anti-biofilm assays, it was determined that after three days, the toxicity of the cross-linked lignin-agarose/SF/ZnCr2O4 nanobiocomposite was less than 13%. Moreover, the small hemolytic effect (1.67%) and high level of prevention in forming a P. aeruginosa biofilm with low OD value (0.18) showed signs of considerable hemocompatibility and antibacterial activity. Besides, according to an in vivo assay study, the wounds of mice treated with the cross-linked lignin-agarose/SF/ZnCr2O4 nanobiocomposite scaffold were almost completely healed in five days. Aside from these biological tests, the structural features were evaluated by FT-IR, EDX, FE-SEM, and TG analyses, as well as swelling ratio, rheological, and compressive mechanical study tests. Additionally, it was concluded that adding silk fibroin and ZnCr2O4 nanoparticles could enhance the mechanical tensile properties of cross-linked lignin-agarose hydrogel, and also an elastic network was characterized for this designed nanobiocomposite.

Reinfection Rate after Successful Helicobacter pylori Eradication in Children.

OBJECTIVE: Reinfection rate of Helicobacter pylori after successful eradication is low in developed countries. This study was performed to determine the reinfection rate of H. pylori during a follow up period of 12 months in Iranian children. METHODS: In this prospective study, children with H. pylori infection were treated with triple omeprazole based regimen. Patients with negative (13)C urea breath test (UBT) performed after 8 weeks of therapy, were followed up by the same test after 1 year. FINDINGS: Thirty seven patients, aged 5 to 17 years, were studied. Among them 25 (67.5%) were boys. After eradication therapy of H. pylori, 34 patients had negative (13)C UBT. Reinfection occurred in 5 (14.7%) patients. Reappearance or continuing symptoms after treatment were associated with higher rate of recurrence (P=0.042). CONCLUSION: Recurrence rate of H. pylori was high in our children. Successful eradication significantly decreased complaints and further symptoms. Follow up and reevaluation of patients is necessary especially when there are symptoms after eradication.