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The ongoing COVID-19 pandemic highlights the urgent need for effective antiviral agents and vaccines. Drug repositioning, which involves modifying existing drugs, offers a promising approach for expediting the development of novel therapeutics. In this study, we developed a new drug, MDB-MDB-601a-NM, by modifying the existing drug nafamostat (NM) with the incorporation of glycyrrhizic acid (GA). We assessed the pharmacokinetic profiles of MDB-601a-NM and nafamostat in Sprague-Dawley rats, revealing rapid clearance of nafamostat and sustained drug concentration of MDB-601a-NM after subcutaneous administration. Single-dose toxicity studies showed potential toxicity and persistent swelling at the injection site with high-dose administration of MDB-601a-NM. Furthermore, we evaluated the efficacy of MDB-601a-NM in protecting against SARS-CoV-2 infection using the K18 hACE-2 transgenic mouse model. Mice treated with 60 mg/kg and 100 mg/kg of MDB-601a-NM exhibited improved protectivity in terms of weight loss and survival rates compared to the nafamostat-treated group. Histopathological analysis revealed dose-dependent improvements in histopathological changes and enhanced inhibitory efficacy in MDB-601a-NM-treated groups. Notably, no viral replication was detected in the brain tissue when mice were treated with 60 mg/kg and 100 mg/kg of MDB-601a-NM. Our developed MDB-601a-NM, a modified Nafamostat with glycyrrhizic acid, shows improved protectivity against SARS-CoV-2 infection. Its sustained drug concentration after subcutaneous administration and dose-dependent improvements makes it a promising therapeutic option.

Since the first emergence of the SARS-CoV-2 variant in late 2020, novel variants have been continuously introduced to the human population, causing severe public health threats. In general, because these variants acquire new genetic mutation/s, it is critical to analyze the biological function of viruses that such mutations can confer.

During the long-term cooling (LTC) phase of a loss-of-coolant accident (LOCA) in a pressurized water reactor (PWR), water is supplied from the containment sump to the reactor coolant system (RCS) by the flooded sump water to the Reactor Vessel (RV) through the broken pipes. As part of the technical efforts for resolving GSI-191 [( Reid and Crytzer, May. 2007) 1 , consideration is needed for the consequences of debris penetrating the sump screen and propagating downstream into the RV. Injection of debris (fiberglass) into the RV during the LTC recirculation phase needs special attention to assure that reactor core cooling is maintained. The point of concern is the potential for debris to adversely affect the reactor core flow paths or heat transfer [ 2 ]. However, all the experiments for proving the coolability of RV have been done with the assumption of the most of debris would be transferred to the RV and the bottom nozzle of the FAs. The purpose of the tests is to quantify the amount of the debris that would be accumulated at the lower plenum and the debris that passes through the FAs since non-conservatism of other researches assumptions that have been used in the past experimental or analytical programs.

As the SARS-CoV-2 pandemic remains uncontrolled owing to the continuous emergence of variants of concern, there is an immediate need to implement the most effective antiviral treatment strategies, especially for risk groups. Here, we evaluated the therapeutic potency of nirmatrelvir, remdesivir, and molnupiravir and their combinations in SARS-CoV-2-infected K18-hACE2 transgenic mice. Systemic treatment of mice with each drug (20 mg/kg) resulted in slightly enhanced antiviral efficacy and yielded an increased life expectancy of only about 20–40% survival. However, combination therapy with nirmatrelvir (20 mg/kg) and molnupiravir (20 mg/kg) in lethally infected mice showed profound inhibition of SARS-CoV-2 replication in both the lung and brain and synergistically improved survival times up to 80% compared to those with nirmatrelvir (P= 0.0001) and molnupiravir (P= 0.0001) administered alone. This combination therapy effectively reduced clinical severity score, virus-induced tissue damage, and viral distribution compared to those in animals treated with these monotherapies. Furthermore, all these assessments associated with this combination were also significantly higher than that of mice receiving remdesivir monotherapy (P= 0.0001) and the nirmatrelvir (20 mg/kg) and remdesivir (20 mg/kg) combination (P= 0.0001), underscored the clinical significance of this combination. By contrast, the nirmatrelvir and remdesivir combination showed less antiviral efficacy, with lower survival compared to nirmatrelvir monotherapy, demonstrating the inefficient therapeutic effect of this combination. The combination therapy with nirmatrelvir and molnupiravir contributes to alleviated morbidity and mortality, which can serve as a basis for the design of clinical studies of this combination in the treatment of COVID-19 patients.IMPORTANCESince SARS-CoV-2 spread rapidly with the emergence of new variants of concerns, it is necessary to develop effective treatment strategies to treat elderly individuals and those with comorbidities. Antiviral therapy using a combination of drugs is more effective in eradicating viruses and will undoubtedly improve the clinical outcome and survival probability of hospitalized SARS-CoV-2 patients. In the current study, we observed three FDA-approved antivirals nirmatrelvir, remdesivir, and molnupiravir have therapeutic significance with moderate survival for their monotherapies against SARS-CoV-2 infected K18-hACE2 mouse model. The combination of nirmatrelvir and molnupiravir showed significant antiviral activity and a higher survival rate of approximately 80%, providing in vivo evidence of the potential utility of this combination. In contrast, nirmatrelvir and remdesivir combination showed less antiviral potency and emphasized the ineffective significance with less survival. The current study suggests that the nirmatrelvir and molnupiravir combination is an effective drug regimen strategy in treating SARS-CoV-2 patients.

The intermetallic compound formations of Ce-Bi on an inert W electrode in the molten LiCl-KCl eutectic with CeCl3 and BiCl3 for an electrolytic reduction process was investigated with various electrochemical techniques of cyclic voltammetry, square wave voltammetry, and open circuit chronopotentiometry. The electrochemical reduction of Ce3+ on the inert electrode at 773 K was observed at more positive potential with Bi3+ than that without Bi3+ due to lowering activity of Ce by intermetallic compound formations. Cyclic voltammogram and square wave voltammogram exhibited four reduction peaks with overlapping signals. Application of peak separation technique allow five intermetallic compounds of BiCe1/2, BiCe, BiCe4/3, BiCe5/3, BiCe2 to be determined. Intermetallic compound formations of Ce-Bi were confirmed with open circuit chronopotentiogram which exhibited five plateau corresponding to a state in which two phases of intermetallic compounds coexist on the electrode surface. Analysis of cyclic voltammograms according to molar ratio of Bi to Ce showed that the amount of CeBi2 and CeBi at the reduction potential above −1.5 V were increased at the higher molar ratio of Bi to Ce. The experimental results indicated that intermetallic compounds of Ce-Bi could be formed on the inert electrode in LiCl-KCl-CeCl3-BiCl3 melt by electrolytic reduction and the type and amount of the resulting intermetallic compound on the inert electrode by electrolytic reduction could be varied depending on the applied potential and molar ratio of Bi to Ce, respectively.

A fiber-optic Cerenkov radiation sensor (FOCRS), which utilizes transparent core of the optical fiber as a sensing material of gamma ray, has been evaluated a feasibility in application of determining radiation release characteristic of spent nuclear fuel by Monte Carlo simulation with GEANT4 simulation toolkit. A simulation model with Westinghouse type 17 × 17 fuel assembly and the FOCRS were constructed with GEANT4 and the nuclide composition of spent nuclear fuel was evaluated with ORIGEN-ARP. The simulation results exhibit that the FOCRS could describe the gamma ray distribution emitted from spent nuclear fuel assembly. The FORCS, therefore, can be used to evaluate gamma ray distribution at extremely radiation environment around the spent nuclear fuel assembly.

A salt waste generated from the pyroprocess contains residual actinides and needs to be purified for recycling of the salt and waste conditioning. A co-reduction process could be considered for removal of residual actinides from the salt waste, which contains lanthanides and residual actinides. In the study, specifically, an effect of Bi(III) ion on the electrochemical reaction of Tb(III) ion was investigated in the molten LiCl-KCl eutectic with BiCl3 and TbCl3 at 773 K using electrochemical techniques of cyclic voltammetry, square wave voltammetry and open circuit chronopotentiometry. Tb(III) has a single redox couple without Bi(III). However, the cyclic voltammograms obtained at tungsten electrode in LiCl-KCl-BiCl3-TbCl3 showed four redox couples. The square wave voltammogram in same condition also showed five reduction peaks. Cyclic voltammogram and square wave voltammogram was resolved to find the accurate peaks for redox reaction. Each peak indicates the formation of Tb-Bi intermetallic compound except Tb(III) reduction peak. From the phase diagram of Tb-Bi, it is inferred that each peak corresponds to TbBi2, TbBi, Tb4Bi3, and Tb5Bi3. The open circuit chronopotentiometry was conducted to estimate Gibbs free energy of formation of Tb-Bi intermetallic compound. The experimental results obtained from three kind of the electrochemical techniques showed that Tb-Bi intermetallic compounds were electrochemically formed under potential of Tb(III) reduction potential by co-reduction of Bi(III) and Tb(III). These results indicate that underpotential deposition by co-reduction could be used for Tb(III) removal from the salt waste with Bi(III).

In this study, a Monte Carlo model has been developed for a Cerenkov-based fiber-optic gamma-ray sensor (CFOGRS) using the GEANT4 simulation toolkit. The detection material for gamma rays in CFOGRS is the transparent silica core of the optical fiber, which is also used for optical signal propagation. The model implemented with the GEANT4 includes the transport process of gamma rays, as well as the physical processes of Compton scattering, the Cerenkov effect, and optical photon propagation within the optical fiber. The model also simulated the applicability of the CFOGRS in a radiation environment by using the Monte Carlo code of GEANT4.

A Rhodamine-based fiber-optic sensor has been developed to detect mercury ions in aqueous environments. The fiber-optic sensorwas composed of a mercury-sensing thin film, plastic optical fibers, and a spectrometer. The mercury-sensing thin film with the syn-thesized Rhodamine derivatives was fabricated with Sol-Gel process. A light emitted by a light source is guided by plastic optical fibersinto the thin film in an aqueous solution and a reflected light is analyzed with the spectrometer. The experiment exhibits that an absor-bance in the thin film is increased as mercury concentration is increased in the solution and the absorbance by mercury is higher thanthat by other heavy metals. The fiber-optic sensor exhibits high chromogenic phenomenon of mercury ions among various heavy metalsand the correlation between absorbance and mercury concentration in the aqueous environments.Keywords: Rhodamine derivative, Sol-Gel process, Absorbance, Mercury, Fiber-optic sensor 1. 서론 최근 화학센서의 소형화 및 기능화를 갖춘 센서에 대한 연구가 활발하게 이루어지고 있다. 이에 따라 분석물의 감지 능력에대한 선택적 상호인식작용을 이용하여 광 신호로 분석되는 광화학적 센서가 각광받고 있다[1]. 광화학 센서의 개발은 다양한전공분야에서 활용되어지고 있다. 중금속에 의한 환경오염 문제가 심각해지면서 금속 이온을 검출하기 위한 광화학센서 개발연구도 여러 차례 진행되고 있다[2].수은은 인체에 유해한 중금속으로, 체내에 유입될 경우 인간의 뇌, 중추신경, 신장, 간 등에 치명적이며, 운동장애와 언어장애 및 마비 증세를 일으킨다[3]. 수은에 의한 위해를 사전에 예방하기 위하여, 수중에 용해된 수은의 실시간 감지가 매우 중요시되고 있다.수은 이온의 검출을 위하여 전압 전류법[4], 원자 흡수 분광법[5]과 같은 여러 가지 기술이 개발되었지만, 측정을 위한 전처리 과정이 복잡하고 정교한 분석 기술이 요구되기 때문에, 현장에서 실시간으로 감시가 불가능하다는 단점을 가진다. 반면에수은 감지 물질의 광학적 특성을 이용하는 광섬유 센서는 현장에서 실시간 검출이 가능하고, 조작이 간단하며, 감도가 높다.또한 감지물질의 반응속도가 빠르기 때문에 순간 측정이 가능하며, 공간에 구애 받지 않는 이점으로 인해 실질적 측면에서매우 유용한 것으로 알려져 있다[6].수은을검출하기 위해 사용되는 여러 물질 중로다민 (Rhodamine)유도체는 Noelting과 Dziewonsky에 의해 1905년 처음 연구되었다[7]. 로다민 유도체는 높은 광 감응적 특성을 가지고 있어다양한 이온들을 검출하는데 많이 사용되고 있다. 로다민 유도체의 고분자를 이용한 금속 감지 센서는 분석하고자 하는 금속 이온과 결합하게 되면 Spirolactam 구조의 개환(ring-opening)에 의해 무색에서 분홍색으로 색의 변화와 강한 형광을 나타낸다[8].로다민 유도체는 형광특성을 이용하여 생물학적 측면[9] 및 수중의 여러 중금속[10,11]을 검출하기 위한 형광 화학센서 분야와, 흡수 스펙트럼을 측정하여 분석 이온의 농도를 정량하기 위한 광화학 센서[12] 분야에서 연구되고 있다. 본 연구에서는 로다민 유도체를 이용하여 수중환경의 수은 검출을 위한 광섬유 센서를 제작하고, 수은의 농도에 따른 흡광강도 변화를 측정분석하여 센서의 성능을 평가하였다.

This paper presents a tunable bandpass filter based on the varactor-loaded composite right- and left-handed transmission line (CRLH-TL). The proposed filter is composed of one CRLH-TL unit cell, which corresponds to the third-order bandpass filter. The tunable bandpass filter is designed using only lumped-elements. The use of lumped elements saves space and lowers the fabrication cost. The size of the proposed tunable bandpass filter is 17 mm × 5 mm, neglecting the feed lines and DC lines. All of the varactors are controlled by one DC bias. The center frequency of the bandpass filter can be controlled by varying the value of the varactors. The tunable range of the center frequency is from 412.5 to 670 MHz. The insertion loss is less than 3 dB, the return loss is more than 10 dB in the passband.

It is necessary to use pressure reducing valves to provide required water pressure in water-based fire suppression systems of the tall buildings. In many cases, however, pressure reducing valves lose their function due to the phenomenon of pressure equalization caused by valve leak. This study carried out performance evaluation of the recently developed pressure reducing valve to prevent pressure equalization and found it can maintain designed pressure reducing ratio within 11% variation and prevent pressure equalization by automatic self-lock function of the piston.

Fiber-optic radiation sensors have been developed to detect gamma-rays generated from radioisotopes. Recently, many studies on the Cerenkov radiation in optical fibers without scintillator materials have been conducted to experimentally investigate their response characteristics against gamma-rays. The purpose of this study is to develop a Monte Carlo-based computer program in order to simulate the Cerenkov-based Fiber-Optic Radiation Sensor and to investigate the response characteristics of the sensor. In the model, the gamma photon generates an electron by Compton scattering and then the electron with velocity greater than the phase velocity of light generates an optical photon by the Cerenkov principle. Finally, the energy spectrum and number of optical photons are evaluated. The computer program is used to simulate the sensors under an environment with Iridium-192 radioisotope. The simulation results exhibited good agreement with experimental results.

A wideband single-layer absorber at X-band adopting trumpet structures is presented. One unit of the proposed absorber is composed of a trumpet-shaped resonator loading four chip resistors, a metallic backplane and an FR-4 (e r = 4.4-j0.02) substrate between them. The absorption is 99% at 10.9 GHz. The full width at half maximum is 95% at 12.7 GHz (6.7–18.7 GHz). The 90% absorption bandwidth is 65% at 12.75 GHz (8.6–16.9 GHz). The size of the unit cell is 5.6 × 5.6 × 2.4 mm3. The proposed absorber is almost insensitive to polarisations of incident waves due to the symmetry of the structure. The results of EM simulation and measurements are in good agreement.

This letter presents two types of metamaterial-inspired absorbers adopting resistive trumpet structures at the X band. The unit cell of the first type is composed of a trumpet-shaped resonator loading a chip resistor, a metallic back plane, and a FR4 (er = 4.4-j 0.02) substrate between them (single-layer). The absorption rate is 99.5% at 13.3 GHz. The full width at half maximum (FWHM) is 95 % at 11.2 GHz (from 5.9 to 16.5 GHz). The size of unit cell is 5.6×5.6×2.4 mm 3 . The second type has been optimized with a 7 Ω/square uniform resistive coating, removing the chip resistors but leading to results comparable to the first type. The proposed absorbers are almost insensitive to polarizations of incident waves due to symmetric geometry.

한천, 키틴, 셀룰로오스, 자일란, 만난과 같은 복합다당류들에 대한 분해능을 나타내는 효소들을 생산하는 해양미생물을 홍조류인 Porphyra dentata로부터 분리하였다. 분리균 BK1은 그람음성, 호기성 간균으로 DNA의 G+C함량은 51.6 mol%를 나타내었다. 주요 isoprenoid quinine 구성성분은 ubiquinone-8로 확인되었고, 주요 세포 지방산은 C16:0, C16:1 w6c, C18:1 w7c로 밝혀졌다. 16S rRNA서열의 비교분석 결과는 분리균 BK1이 Pseudomonas 속의 일원인 것으로 확인되었다. 이러한 결과를 바탕으로 분리균 BK1은 Pseudomonas sp. BK1으로 명명하였다.

A gene (pagA) encoding beta-agarase from Pseudomonas sp. SK38 was cloned and expressed in Escherichia coli. The structural gene consists of 1011 bp encoding 337 amino acids with a predicted molecular weight of 37326 and has a signal peptide of 18 amino acids. The deduced amino acid sequence showed 57% and 58% homology to beta-agarase from Pseudoalteromonas atalntica and Aeromonas sp., respectively. The recombinant enzyme was purified and biochemically characterized. The enzyme had maximum activity at pH 9 and 30 degrees C. It was stable at pHs from 8 to 9 and below 37 degrees C.

We studied the performance improvement of HIT solar cells by optimizing H 2 plasma exposure and deposition of thin a-S:H layer on c-Si. With increasing H 2 treatment time, the V OC increases until 80 s and then decreases, indicating the optimum time is 80 s. It is found that the cell performance is almost the same with and without a thin a-Si:H layer when 80 s plasma is treated on the c-Si before i-layer deposition. The conversion efficiency of 14.04% was achieved at the substrate temperature of 160 °C.

SUMMARY The genes encoding the α and β subunits of the phycoerythrin (PE) from the red algae Porphyra yezoensis Ueda and Porphyra tenera K jell man were isolated by PCR amplification. The PE u subunit gene was located downstream (+ 74bp) of the PE β sub-unit encoding gene. The PE amino acid sequences of P. yezoensis and P. tenera, as deduced from the nucleotide sequence of the cpeA and cpeB genes, were respectively, 83–89% and 84–87% identical to species in other red algal genera. They were also 64–73% (a subunit) and 61–71% (β subunit) identical to the cyanobacterial group. The high homology of the deduced ammo acid sequences of red algal and cyanobacterial PE supports the view that the red algal plastid originated from endosymbiotic cyanobacteria. Reverse transcriptase polymerase chain reaction analysis confirmed that cpeA and cpeB are cotranscribed.