Fingerprint ridges allow primates to regulate grip.

Fingerprints are unique to primates and koalas but what advantages do these features of our hands and feet provide us compared with the smooth pads of carnivorans, e.g., feline or ursine species? It has been argued that the epidermal ridges on finger pads decrease friction when in contact with smooth surfaces, promote interlocking with rough surfaces, channel excess water, prevent blistering, and enhance tactile sensitivity. Here, we found that they were at the origin of a moisture-regulating mechanism, which ensures an optimal hydration of the keratin layer of the skin for maximizing the friction and reducing the probability of catastrophic slip due to the hydrodynamic formation of a fluid layer. When in contact with impermeable surfaces, the occlusion of the sweat from the pores in the ridges promotes plasticization of the skin, dramatically increasing friction. Occlusion and external moisture could cause an excess of water that would defeat the natural hydration balance. However, we have demonstrated using femtosecond laser-based polarization-tunable terahertz wave spectroscopic imaging and infrared optical coherence tomography that the moisture regulation may be explained by a combination of a microfluidic capillary evaporation mechanism and a sweat pore blocking mechanism. This results in maintaining an optimal amount of moisture in the furrows that maximizes the friction irrespective of whether a finger pad is initially wet or dry. Thus, abundant low-flow sweat glands and epidermal furrows have provided primates with the evolutionary advantage in dry and wet conditions of manipulative and locomotive abilities not available to other animals.

Full manipulation of transparency and absorption through direct tuning of dark modes in high-Q Fano metamaterials.

Controlling the line shape of Fano resonance has continued to attract significant research attention in recent years owing to its practical applications such as lasing, biosensing, and slow-light devices. However, controllable Fano resonances always require stringent alignment of complex symmetry-breaking structures; therefore, the manipulation can only be performed with limited degrees of freedom and a narrow tuning range. This work demonstrates dark-mode excitation tuning independent of the bright mode for the first time, to the authors' knowledge, in asymmetric Fano metamaterials. Metallic subwavelength slits are arranged to form asymmetric unit cells and generate a broad and bright (radiative) Fabry-Perot mode and a sharp and dark (non-radiative) surface mode. The introduction of the independent radial and angular asymmetries realizes independent control of the Fano phase (q) and quality factor (Q). This tunability provides a dynamic phase shift while maintaining a high-quality factor, enabling switching between nearly perfect transmission and absorption, which is confirmed both numerically and experimentally. The proposed scheme for fully controlled Fano systems can aid practical applications such as phase-sensitive switching devices.

Ultra-wideband transmission filter based on guided-mode resonances in two terahertz metasurfaces.

This paper reports on a broadband transmission filter that employs the guided mode resonances pertaining to a terahertz metasurface composed of metallic gold disks with a quartz slab. Unlike structures involving conventional metasurfaces, two identical metasurfaces are placed on the upper and lower sides of a thick quartz slab. This structure can excite both even and odd guided mode resonances. The interaction of the two resonances at similar frequencies produces a broadband transmission peak. The sharp spectral feature of each resonance leads to the abrupt degradation of the transmission at the spectral edge, which can enable the development of the filter application. The proposed scheme can facilitate practical applications such as those of broadband filters at a terahertz frequency.

Epicutaneous Allergen Administration with Microneedles as a Novel Method of Immunotherapy for House Dust Mite (HDM) Allergic Rhinitis.

PURPOSE: Epicutaneous immunotherapy (EPIT) is being studied as a method for treating allergic rhinitis because of skin immunology, user convenience and enhanced patient compliance. However, the use of EPIT is limited because of the very low skin permeability of the allergen. In this study, the limitations of EPIT were overcome by using sophisticated delivery with microneedles. The immunological efficacy of this method was studied in a murine model of house dust mite (HDM) allergic rhinitis. METHODS: The length of the microneedles was 400 µm, and the coating formulation containing HDM was locally distributed near the end of the microneedle tips. The change of distribution of FITC-dextran in porcine skin in vitro was observed over time using a confocal microscope. The effect of immunotherapy in the allergic rhinitis model, sensitized by HDM-coated microneedles (HDM MNs), was observed according to the amount of HDM applied. RESULTS: The microneedles delivered the coating formulation with precision into the porcine skin layer, and the coated formulation on the microneedles was all dissolved in the porcine skin in vitro within 20 min of administration and then gradually diffused into the skin layer. When HDM MNs were administered to mice, a 0.1-µg dose of HDM provided the most effective immunization, and improved efficacy was shown between 0.1- and 0.5- µg doses of HDM. CONCLUSIONS: Effective immunotherapy can be achieved by precision delivery of the allergen into the skin layer, and microneedles can provide effective immunological therapy by delivering the appropriate amount of allergen.

Suppression of tumorigenesis in mitochondrial NADP(+)-dependent isocitrate dehydrogenase knock-out mice.

The tumor host microenvironment is increasingly viewed as an important contributor to tumor growth and suppression. Cellular oxidative stress resulting from high levels of reactive oxygen species (ROS) contributes to various processes involved in the development and progress of malignant tumors including carcinogenesis, aberrant growth, metastasis, and angiogenesis. In this regard, the stroma induces oxidative stress in adjacent tumor cells, and this in turn causes several changes in tumor cells including modulation of the redox status, inhibition of cell proliferation, and induction of apoptotic or necrotic cell death. Because the levels of ROS are determined by a balance between ROS generation and ROS detoxification, disruption of this system will result in increased or decreased ROS level. Recently, we demonstrated that the control of mitochondrial redox balance and cellular defense against oxidative damage is one of the primary functions of mitochondrial NADP(+)-dependent isocitrate dehydrogenase (IDH2) that supplies NADPH for antioxidant systems. To explore the interactions between tumor cells and the host, we evaluated tumorigenesis between IDH2-deficient (knock-out) and wild-type mice in which B16F10 melanoma cells had been implanted. Suppression of B16F10 cell tumorigenesis was reproducibly observed in the IDH2-deficient mice along with significant elevation of oxidative stress in both the tumor and the stroma. In addition, the expression of angiogenesis markers was significantly down-regulated in both the tumor and the stroma of the IDH2-deficient mice. These results support the hypothesis that redox status-associated changes in the host environment of tumor-bearing mice may contribute to cancer progression.

Surface-coupling of Cerenkov radiation from a modified metallic metamaterial slab via Brillouin-band folding.

Metallic metamaterials with positive dielectric responses are promising as an alternative to dielectrics for the generation of Cerenkov radiation [J.-K. So et al., Appl. Phys. Lett. 97(15), 151107 (2010)]. We propose here by theoretical analysis a mechanism to couple out Cerenkov radiation from the slab surfaces in the transverse direction. The proposed method based on Brillouin-zone folding is to periodically modify the thickness of the metamaterial slab in the axial direction. Moreover, the intensity of the surface-coupled radiation by this mechanism shows an order-of-magnitude enhancement compared to that of ordinary Smith-Purcell radiation.

High performance CNT point emitter with graphene interfacial layer.

Carbon nanotubes (CNTs) have great potential in the development of high-power electron beam sources. However, for such a high-performance electronic device, the electric and thermal contact problem between the metal and CNTs must be improved. Here, we report graphene as an interfacial layer between the metal and CNTs to improve the interfacial contact. The interfacial graphene layer results in a dramatic decrease of the electrical contact resistance by an order of 2 and an increase of the interfacial thermal conductivity by 16%. Such a high improvement in the electrical and thermal interface leads to superior field emission performance with a very low turn-on field of 1.49 V µm(-1) at 10 µA cm(-2) and a threshold field of 2.00 V µm(-1) at 10 mA cm(-2), as well as the maximum current of 16 mA (current density of 2300 A cm(-2)).

The effect of Asian sand dust-activated respiratory epithelial cells on activation and migration of eosinophils.

UNLABELLED: CONTEST: Asian sand dust (ASD) contains various chemical and microbiological materials. ASD aggravate the inflammatory response of respiratory epithelial cells and symptoms of asthma. OBJECTIVE: To evaluate the inflammatory effects of ASD on the activation of bronchial epithelial cells and the effect on the activation and migration of eosinophils. MATERIALS AND METHODS: BEAS-2B cells were exposed to three forms of ASD: particles less than 10 µm in diameter (PM), dried sand dust (SD) and sand dust collected from the Gobi Desert (GB). Activation of the epithelial cells was determined using interleukin-6 (IL-6), IL-8, granulocyte macrophage colony-stimulating factor (GM-CSF), regulated on activation normal T expressed and secreted (RANTES), and eotaxin. Eosinophil migration was induced with bronchial epithelial cell conditioned medium. Eosinophils were stimulated with the ASDs and production of superoxide and eosinophil cationic protein was measured. RESULTS: PM and SD enhanced the production of IL-6, IL-8 and RANTES. However, only IL-6 production was significantly increased with GB. Conditioned medium stimulated PM and SD enhanced the migration of eosinophils. PM and SD strongly activated eosinophils. DISCUSSION AND CONCLUSIONS: ASD, which contains smaller particles and air pollutants, might exacerbate the inflammatory process of bronchial tissue and asthmatic symptoms with the production of inflammatory mediators and tissue eosinophilia.

Safety surveillance of the NVX-CoV2373 COVID-19 vaccine among Koreans aged 18 years and over.

BACKGROUND: In the Republic of Korea (Korea), the NVX-CoV2373 (Novavax) coronavirus disease 2019 (COVID-19) vaccination was administered to 18-year-olds and over from February 14, 2022. This study sought to assess the frequency and severity of reported adverse events following the Novavax COVID-19 vaccination in Korea. METHODS: Adverse events based on two national vaccine safety data were analyzed; the COVID-19 vaccination management system (CVMS) and the text-message survey (TMS). RESULTS: CVMS identified that the reporting rate of adverse events per 100,000 doses were lower after booster doses (84.0) than after dose 1 (254.6) or dose 2 (272.9); and in 65-year-olds and over (83.4) than in 18- to 64-year-olds (168.1). The TMS found that local and systemic adverse events were lower in 65-year-olds and over than in 18- to 64-year-olds (p < 0.001). CONCLUSIONS: Overall, we identified no major safety issues and fewer adverse events following the Novavax COVID-19 vaccination among 65-year-olds and over in Korea.

Household secondary attack rates and risk factors during periods of SARS-CoV-2 Delta and Omicron variant predominance in the Republic of Korea.

BACKGROUND: The household secondary attack rate (SAR) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important indicator for community transmission. This study aimed to characterize transmission by comparing household SARs and identifying risk factors during the periods of Delta and Omicron variant predominance in Republic of Korea. METHODS: We defined the period of Delta variant predominance (Delta period) as July 25, 2021 to January 15, 2022, and the period of Omicron variant predominance (Omicron period) as February 7 to September 3, 2022. The number of index cases included was 214,229 for the Delta period and 5,521,393 for the Omicron period. To identify the household SARs and risk factors for each period, logistic regression was performed to determine the adjusted odds ratio (aOR). RESULTS: The SAR was 35.2% for the Delta period and 43.1% for the Omicron period. The aOR of infection was higher in 2 groups, those aged 0 to 18 years and ≥75 years, compared to those aged 19 to 49 years. Unvaccinated individuals (vs. vaccinated individuals) and individuals experiencing initial infection (vs. individuals experiencing a second or third infection) had an increased risk of infection with SARS-CoV-2. CONCLUSION: This study analyzed the household SARs and risk factors. We hope that the results can help develop age-specific immunization plans and responses to reduce the SAR in preparation for emerging infectious diseases or potential new variants of SARS-CoV-2.

Self-reported adverse events after 2 doses of COVID-19 vaccine in Korea.

OBJECTIVES: In Korea, a national coronavirus disease 2019 (COVID-19) vaccination program was implemented, including 4 vaccines against COVID-19. A text messaging-based survey, in addition to a passive adverse event reporting system, was launched to quickly report unusual symptoms post-vaccination. This study compared the frequency of adverse events after COVID-19 vaccination based on the vaccine type and the type of 2-dose regimen (homologous or heterologous). METHODS: Self-reported adverse events were collected through a text-message survey for 7 days after each vaccination. This study included 50,950 vaccine recipients who responded to the survey at least once. Informed consent to receive surveys via text was obtained from the vaccine recipients on the date of first vaccination. RESULTS: The recipients of mRNA vaccines reported local and systemic reactions 1.6 times to 2.8 times more frequently after dose 2 than after dose 1 (p<0.001), whereas ChAdOx1-S recipients reported significantly fewer local and systemic reactions after dose 2 than after dose 1 (p<0.001). Local and systemic reactions were approximately 2 times and 4 times more frequent for heterologous vaccination than for BNT162b2/BNT162b2 and ChAdOx1-S/ChAdOx1-S regimens, respectively. Young individuals, female, and those receiving heterologous vaccine regimens including ChAdOx1-S/BNT162b2 vaccines reported more adverse events than older participants, male, and those with homologous vaccine regimens. CONCLUSIONS: Although a heterologous regimen, youth, and female sex were associated with a higher risk of adverse reactions after COVID-19 vaccination, no critical issues were noted. Active consideration of heterologous schedules based on the evidence of efficacy and safety appears desirable.

Safety monitoring of COVID-19 vaccines: February 26, 2021, To June 4, 2022, Republic of Korea.

As of June 2022, 5 coronavirus disease 2019 (COVID-19) vaccine brands have been used in Korea's national immunization program. The Korea Disease Control and Prevention Agency has enhanced vaccine safety monitoring through a passive web-based reporting system and active text message-based monitoring. In this study, an enhanced safety monitoring system for COVID-19 vaccines is described and the frequencies and types of adverse events (AEs) associated with the 5 COVID-19 vaccine brands were analyzed. AE reports from the web-based COVID-19 Vaccination Management System and text message-based reports from recipients were analyzed. AEs were classified as nonserious or serious (e.g., death or anaphylaxis). The AE reporting rates were calculated based on the number of COVID-19 vaccine doses administered. A total of 125,107,883 doses were administered in Korea from February 26, 2021, to June 4, 2022. Among them, 471,068 AEs were reported, of which 96.1% were nonserious and 3.9% were serious. Among the 72,609 participants in the text message-based AE monitoring process, a higher AE rate of local and systemic reactions was reported for the 3rd versus 1st doses. A total of 874 cases of anaphylaxis (7.0 per 1,000,000 doses), 4 cases of thrombocytopenia syndrome (TTS), 511 cases of myocarditis (4.1 per 1,000,000 doses), and 210 cases of pericarditis (1.7 per 1,000,000 doses) were confirmed. Six fatalities were causally associated with COVID-19 vaccination (1 of TTS and 5 of myocarditis). Young adult age and female sex were related with a higher AE rate for COVID-19 vaccines. Most reported AEs were nonserious and of mild intensity.

Safety monitoring of COVID-19 vaccination among adolescents aged 12 to 17 years old in the Republic of Korea.

OBJECTIVES: This study aimed to disseminate information on coronavirus disease 2019 (COVID-19) vaccine safety among adolescents aged 12 to 17 years in the Republic of Korea. METHODS: Two databases were used to assess COVID-19 vaccine safety in adolescents aged 12 to 17 years who completed the primary Pfizer-BioNTech vaccination series. Adverse events reported to the web-based COVID-19 vaccination management system (CVMS) and collected in the text message-based system were analyzed. RESULTS: From March 5, 2021 to February 13, 2022, 12,216 adverse events among 12- to 17-yearolds were reported to the CVMS, of which 97.1% were non-serious adverse events and 2.9% were serious adverse events, including 85 suspected cases of anaphylaxis, 74 suspected cases of myocarditis and/or pericarditis, and 2 deaths. From December 13, 2021 to January 26, 2022, 10,389 adolescents responded to a text message survey, and local/systemic adverse events were more common after dose 2 than after dose 1. The most commonly reported events following either vaccine dose were pain at the injection site, headache, fatigue/tiredness, and myalgia. CONCLUSION: The overall results are consistent with previous findings; the great majority of adverse events were non-serious, and serious adverse events were rare among adolescents aged 12 to 17 years following Pfizer-BioNTech COVID-19 vaccination.

Adverse events of the Pfizer-BioNTech COVID-19 vaccine in Korean children and adolescents aged 5 to 17 years.

OBJECTIVES: This study aimed to identify potential safety signals and adverse events following the primary Pfizer-BioNTech coronavirus disease 2019 (COVID-19) vaccination series among children and adolescents aged 5 to 17 years in the Republic of Korea. METHODS: Adverse events reported through the COVID-19 vaccination management system (CVMS, a web-based passive vaccine safety surveillance system) and adverse events and health conditions collected from a text message-based survey were analyzed. RESULTS: A total of 14,786 adverse events among 5 to 17-year-old children and adolescents were reported in the CVMS; 14,334 (96.9%) were non-serious and 452 (3.1%) were serious, including 125 suspected cases of acute cardiovascular injury and 101 suspected cases of anaphylaxis. The overall reporting rate was lower in 5 to 11-year-old children (64.5 per 100,000 doses) than in 12 to 17-year-old adolescents (300.5 per 100,000 doses). The text message survey identified that local and systemic adverse events after either dose were reported less frequently in 5 to 11-year-old children than in 12 to 17-year-old adolescents (p<0.001). The most commonly reported adverse events were pain at the injection site, myalgia, headache, and fatigue/tiredness. CONCLUSION: The overall results are consistent with the results of controlled trials; serious adverse events were extremely rare among 5 to 17-year-old children and adolescents following Pfizer-BioNTech COVID-19 vaccination. Adverse events were less frequent in children aged 5 to 11 years than in adolescents aged 12 to 17 years.

Clinical and genetic analyses of three Korean families with hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal-dominant vascular disorder, characterized by recurrent epistaxis, mucocutaneous telangiectases, and arteriovenous malformations (AVMs) in various visceral organs. Endoglin (ENG) and activin receptor-like kinase 1 (ACVRL1; ALK1), receptors for transforming growth factor-ß (TGF-ß) superfamily, have been identified as the principal HHT-causing genes. METHODS: Three unrelated Korean HHT patients and their asymptomatic as well as symptomatic family members were genetically diagnosed by sequencing whole exons and their flanking regions of ENG and ACVRL1. Functionality of an aberrant translation start codon, which is created by a substitution mutation at the 5'-untranslated region (UTR) of ENG found in a HHT family, was tested by transient in vitro transfection assay. Decay of the mutant transcripts was also assessed by allele-specific expression analysis. RESULTS: Two ENG and one ACVRL1 mutations were identified: a known ENG mutation (c.360+1G > A; p.Gly74_Tyr120del); a novel ENG mutation (c.1-127C > T); and a novel ACVRL1 mutation (c.252_253insC; p.Val85fsX168). We further validated that the 5'-UTR ENG mutation prevents translation of ENG from the biological translation initiation site of the mutant allele, and leads to degradation of the mutant transcripts. CONCLUSIONS: This is the first experimental demonstration that a 5'-UTR mutation can prevent translation of ENG among HHT patients, and further supports the previous notion that haploinsufficiency is the primary mechanism of HHT1. Our data also underscore the importance of including exons encoding 5' UTR for HHT mutation screening.

Double-Blind Placebo-Controlled Trial of Bepotastine Salicylate in Patients With Allergic Rhinitis.

OBJECTIVES/HYPOTHESIS: To evaluate the efficacy and safety of a slow-release form of bepotastine salicylate (HL151, Belion CR) in patients with perennial allergic rhinitis (PAR). STUDY DESIGN: Double-blind, placebo-controlled multicenter comparative study. METHODS: Two hundred seventy-two PAR patients (aged 19-65 years) were studied to determine the efficacy and safety of HL151 (20 mg once daily administration) relative to those of a placebo in terms of improvements in total and nasal symptom scores. The subjects were randomized to the placebo (n = 138) or HL151 group (n = 134, 20 mg orally once daily for 4 weeks), and reflective and instantaneous total nasal symptom scores (TNSS) were measured daily in comparison with baseline. Among 272 subjects, 229 subjects (119 in the placebo group, 110 in the HL151 group) who completed the study were included for efficacy analysis. RESULTS: Instantaneous and reflective TNSS and nasal symptoms such as rhinorrhea, nasal itching, and sneezing at 2 and 4 weeks showed that HL151 was superior to the placebo (all P < .05). There were no significant differences in terms of adverse events and adverse drug reactions between the two groups. Regarding serious adverse events, there was only one case of acute hepatitis B, which was reported not to be associated with HL151. CONCLUSIONS: This multicenter trial showed that once-daily use of HL151 is efficacious and safe in adult patients with PAR and could improve compliance due to its convenience. LEVEL OF EVIDENCE: 1b Laryngoscope, 131:E702-E709, 2021.

Genetic Variants and Clinical Phenotypes in Korean Patients With Hereditary Hemorrhagic Telangiectasia.

OBJECTIVES: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder characterized by recurrent epistaxis, telangiectasia, and visceral arteriovenous malformations (AVMs). Activin A receptor-like type 1 (ACVRL1/ALK1) and endoglin (ENG) are the principal genes whose mutations cause HHT. No multicenter study has yet investigated correlations between genetic variations and clinical outcomes in Korean HHT patients. METHODS: Seventy-two members from 40 families suspected to have HHT based on symptoms were genetically screened for pathogenic variants of ACVRL1 and ENG. Patients with genetically diagnosed HHT were also evaluated. RESULTS: In the HHT genetic screening, 42 patients from 24 of the 40 families had genetic variants that met the pathogenic criteria (pathogenic very strong, pathogenic strong, pathogenic moderate, or pathogenic supporting) based on the American College of Medical Genetics and Genomics Standards and Guidelines for either ENG or ACVRL1: 26 from 12 families (50%) for ENG, and 16 from 12 families (50%) for ACVRL1. Diagnostic screening of 42 genetically positive HHT patients based on the Curaçao criteria revealed that 24 patients (57%) were classified as having definite HHT, 17 (41%) as having probable HHT, and 1 (2%) as unlikely to have HHT. Epistaxis was the most common clinical presentation (38/42, 90%), followed by visceral AVMs (24/42, 57%) and telangiectasia (21/42, 50%). Five patients (12%) did not have a family history of HHT clinical symptoms. CONCLUSION: Only approximately half of patients with ACVRL1 or ENG genetic variants could be clinically diagnosed as having definite HHT, suggesting that genetic screening is important to confirm the diagnosis.

Asian sand dust enhances rhinovirus-induced cytokine secretion and viral replication in human nasal epithelial cells.

CONTEXT: Asian sand dust (ASD) originating in the arid deserts of Mongolia and China causes annual severe air pollution events in the Asia-Pacific area, including Korea, Japan, and China. ASD is thought to impact public health by aggravating or inducing respiratory illness. Among the most common respiratory illnesses is the common cold caused by rhinovirus (RV) infection. To date, however, the impact of ASD on RV infection has not been studied. OBJECTIVE: In this study, we investigated the effect of ASD on RV infection in human nasal epithelial cells. METHODS: Primary human nasal epithelial cells grown at an air-liquid interface were treated with ASD and/or RV. After RV infections were confirmed using semi-nested reverse transcription-polymerase chain reaction (RT-PCR), mRNA expression and protein secretion of the inflammatory cytokines interferon-γ (IFN-γ), interleukin-1ß (IL-1ß),IL-6, and IL-8, indicators of the severity of RV-induced inflammation, were measured by real-time PCR and enzyme-linked immunosorbent assays. Viral titer was also assayed by culturing viruses to compare viral replication between RV-only and ASD-plus-RV groups. RESULTS: ASD significantly increased RV-induced IFN-γ, IL-1ß, IL-6, and IL-8 mRNA levels and protein secretion in primary nasal epithelial cells. In addition, ASD caused a significant increase in RV replication. CONCLUSIONS: Our results suggest that ASD may potentiate common cold symptoms associated with RV infection not only by enhancing IFN-γ, IL-1ß, IL-6, and IL-8 secretion, but also by increasing viral replication.

Performance of an impedance-variable pulsed high-power electron-beam accelerator based on energy efficient transmission.

Versatile high-power pulsed electron-beam accelerators that meet the requirements of pulsed high-power specifications are needed for appropriate applications in medical industry, defense, and other industries. The pulsed electron beam accelerator comprising a Marx generator and Blumlein pulse forming line (PFL) is designed to accelerate the electron beams at the level of 1 MeV when electrostatically discharging. The performance specifications of Marx generators consisting of a 100 kV DC power supply, R-L-C circuit, and high voltage switch are at a maximum 800 kV. At this time, by using the capacitance mismatching principle between the Marx generator and the Blumlein PFL under the law of preserving the amount of charge, it is possible to generate a high voltage in the form of a square pulse up to about 1.1 MV, as much as 1.37 times the charged voltage of the Marx generator. As a result, energy transmission from the Marx generator with a high efficiency of about 85% to the Blumlein PFL is possible. The aim of this study is that the pulsed high-power electron-beam accelerator can be used to change the diode impedance, and the energy of the accelerated electron beam reaches a level of 1 MeV with the square pulse width of about 100 ns at the flat-top in the range of relativistic electron beam generation. Performance tests were securely carried out by installing a dummy load based on CuSO4 solution varying the diode impedance to deter damage to the circuit by preventing reflected waves from being generated in the load.

Miniaturized two-stack Blumlein pulser with a variable repetition-rate for non-thermal irreversible-electroporation experiments.

Non-thermal irreversible electroporation (NTIRE) to avoid thermal damage to cells during intense DC ns pulsed electric fields (nsPEFs) is a recent modality for medical applications. This mechanism, related to bioelectrical dynamics of the cell, is linked to the effect of a DC electric field and a threshold effect with an electrically stimulated membrane for the charge distribution in the cell. To create the NTIRE condition, the pulse width of the nsPEF should be shorter than the charging time constant of the membrane related to the cell radius, membrane capacitance, cytoplasm resistivity, and medium resistivity. It is necessary to design and fabricate a very intense nanosecond DC electric field pulser that is capable of producing voltages up to the level of 100 kV/cm with an artificial pulse width (∼ns) with controllable repetition rates. Many devices to generate intense DC nsPEF using various pulse-forming line technologies have been introduced thus far. However, the previous Blumlein pulse-generating devices are clearly inefficient due to the energy loss between the input voltage and the output voltage. An improved two-stage stacked Blumlein pulse-forming line can overcome this limitation and decrease the energy loss from a DC power supply. A metal oxide silicon field-effect transistor switch with a fast rise and fall time would enable a high repetition rate (max. 100 kHz) and good endurance against very high voltages (DC ∼ 30 kV). The load is designed to match the sample for exposure to cell suspensions consisting of a 200 Ω resistor matched with a Blumlein circuit and two electrodes without the characteristic RC time effect of the circuit (capacitance =0.174 pF).