Thermal regimes of HTS cylinders operating in devices for fault current limitation

We reveal obstacles related to the application of HTS cylinders in current limiting devices based on the superconducting - normal state transition. It is shown that, at the critical current density achieved presently in bulk materials, and especially in BSCCO-2212, the required thickness of the cylinder wall in a full-scale inductive device achieves several centimeters. A simple mathematical model of the operation of an inductive fault current limiter (FCL) is used to show that such cylinders cannot be cooled in admissible time after a fault clearing and, hence, the inductive FCLs and current-limiting transformers employing BSCCO cylinders do not return to the normal operation in the time required. For the recovery even with a non-current pause in the circuit, the cylinders are needed with the critical current density by an order higher than the existed ones.Comment: 15 pages, 5 figure

Calculation principles for a superconducting inductive FCL and a current-limiting transformer

We present general principles of the parameters calculation and application of two power devices: an inductive fault current limiter and a current-limiting transformer. Both the devices are based on the superconducting - normal state transition in a superconducting switching element magnetically coupled with a primary winding. The relationships between the design parameters of the devices and the limited current, losses and temperature in the superconducting element were investigated. It is shown that, in spite of similarity, the devices have distinctive features manifested in different depths of the fault current limitation. The case of performance of the superconducting winding in the form of HTS BSCCO hollow cylinders is analyzed. Basic parameters of the devices are evaluated for their application in 45 MVA power circuit. Problems of the transition into the normal state and recovery of the superconducting state in the switching element are discussed.Comment: 26 pages including 11 figures and 1 table, submitted to IEEE Transactions on Applied Superconductivit

Dynamic response of HTS composite tapes to pulsed currents

Dynamic voltage-current characteristics of an HTS Ag/BiSCCO composite tape are studied both experimentally and theoretically. The tape is subjected by pulsed currents with different shapes and magnitude and voltage traces are measured using the four-point method with different location of potential taps on the sample surface. Clockwise and anticlockwise hysteresis loops are obtained for the same sample depending on location of the potential taps. The dynamic characteristics deviate substantially from the DC characteristic, especially in the range of low voltages where a criterion for the critical current value is usually chosen (1-10 mkV/cm). The critical current determined from dynamic characteristics and its change with the pulse magnitude depend on location of the potential taps and on the curve branch chosen for the critical current determination (ascending or descending). The theoretical analysis is based on a model of the magnetic flux diffusion into a composite tape for a superconductor described by the flux creep characteristic. Numerical simulation based on this model gives the results in good agreement with the experimental ones and explains the observed peculiarities of the dynamic characteristics of HTS composite tapes. The difference between the magnetic diffusion into a tape and a slab is discussed.Comment: 18 pages, 13 figure

An improved design of an inductive fault current limiter based on a superconducting cylinder

The paper deals with basic designs of a fault current limiter of the transformer type which differ each other by the mutual location of a primary winding and a superconducting short-circuited cylinder. Theoretical study of the main parameters of the different designs is performed in the framework of the critical state model and shows that the most effective is a design in which the primary winding is divided to two sections with equal turn numbers. The sections are placed inside and outside of the cylinder and connected in series. Such arrangement of the windings leads to a substantial reduction of AC losses in the superconducting cylinder, an increase of the activation current and a decrease of the inductive reactance in the normal regime of a protected circuit. The experimental results obtained on the laboratory model with a BSSCO cylinder confirm the theoretical predictions.Comment: 17 pages, 9 figure

Nanomedicines towards targeting intracellular Mtb for the treatment of tuberculosis

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), causes the most human deaths than any other diseases from a single infectious agent. Treatments are long and costly and have many associated side effects. Intracellular bacilli are slow growing and difficult to target, which is augmenting the emergence of multi?drug resistance. A hallmark trait of TB is the formation of granulomas, chronic cellular aggregates, which limit bacterial growth but provides a survival reservoir where bacilli may disseminate from. Targeting intracellular Mtb is challenging, but nanomedicine may offer a solution. Nanomedicine is a significantly growing research area and offers the potential for specific disease targeting, dosage reduction, and intracellular drug delivery. This review discusses the application of the various forms of nanomedicine towards targeting of Mtb

Entanglement in nuclear quadrupole resonance

Entangled quantum states are an important element of quantum information techniques. We determine the requirements for states of quadrupolar nuclei with spins >1/2 to be entangled. It was shown that entanglement is achieved at low temperature by applying a magnetic field to a quadrupolar nuclei possess quadrupole moments, which interacts with the electricfield gradient produced by the charge distribution in their surroundings.Comment: 9 pages, 5 figure

ФОТОДИНАМИЧЕСКАЯ ИНАКТИВАЦИЯ ПАТОГЕННЫХ БАКТЕРИЙ В БИОПЛЕНКАХ С ИСПОЛЬЗОВАНИЕМ НОВЫХ СИНТЕТИЧЕСКИХ ПРОИЗВОДНЫХ БАКТЕРИОХЛОРИНА

Bacteriochlorins as the antimicrobial photosensitizers have a promising future in the face of the unrelenting increase in antimicrobial resistance. The goal of this study was to investigate the infl uence of lipophilicity and number of positively charged  substituents in these molecules on the photodynamic inactivation  (PDI) of biofi lm bacteria in vitro. Testing how bacteriochlorin  derivatives with different properties affect microbes will allow to  determine the optimal ratio of these parameters within a single  molecule. We have investigated 4 bacteriochlorin derivatives, all of  which were synthesized in Organic Intermediates and Dyes Institute. These were: hydrophobic neutral meso-tetra(3-pyridyl)  bacteriochlorin (ВС1), amphyphilic tetracationic meso-tetra(1- undecyl-3-pyridyl)bacteriochlorin tetrabromide (ВС2), hydrophilic  tetracationic meso-tetra[1-(4'-bromobutyl)-3-pyridyl]bacteriochlorin  tetrabromide (ВС3) and octacationic meso-tetra[1-(4'-pyridiniobutyl) -3-pyridyl]bacteriochlorin octabromide (ВС4) . The water-soluble  cationic bacteriochlorin derivatives showed the most effective PDI of  bacteria in biofi lms. While tetracationic BC3 caused total inactivation of S. aureus 15, octacationic BC4 was bactericidal for P. aeruginosa  32 to the same degree (>99.999%). Interestingly, increasing the  number of cationic substituents from 4 to 8 in bacteriochlorin  molecules enhances bactericidal action against gram-negative  bacteria in biofi lms. The lack of charge-carrying groups and high  degree of lipophilicity of PS have negative impact on PDI of biofi lm  bacteria. Bacterial membrane damage as a result of PDI can be one of the causes of cell death.Производные бактериохлорина, как антимикробные фотосенсибилизаторы, имеют серьезные перспективы в связи с растущей множественной антибиотикорезистентностью бактерий. В  работе было изучено in vitro влияние количества положительно заряженных заместителей и  липофильности молекулы синтетических производных бактериохлорина на эффективность фотодинамической инактивации бактерий в биопленках с целью определить  оптимальное соотношение этих параметров. Были исследованы четыре синтетических  производных бактериохлорина, синтезированные во ФГУП «ГНЦ «НИОПИК»: гидрофобный нейтральный мезо-тетра(3-пиридил)бактериохлорин (ВС1), амфифильный  тетракатионный мезо-тетра(1-ундецил-3-пиридил) бактериохлорин тетрабромид (ВС2),  гидрофильные тетракатионный мезо-тетра[1-(4'-бромбутил)-3-пиридил]бактериохлорин тетрабромид (ВС3) и октакатионный мезо-тетра[1-(4'-пиридиниобутил)-3-пиридил]бактериохлорин октабромид (ВС4). Наибольшую эффективность в фотоинактивации бактерий в биопленках показали  водорастворимые катионные производные бактериохлорина. Полную гибель бактерий в биопленках (99,999% и более) вызывали для S. aureus 15 тетракатионный ВС3, а для P. aeruginosa 32 октакатионный ВС4. В отношении грамотрицательных бактерий в биопленках  увеличение числа катионных групп у фотосенсибилизатора от 4 до 8 усиливало  бактерицидное действие. Отсутствие заряда и высокая липофильность молекулы фотосенсибилизатора оказывали негативное влияние на фотодинамическую  инактивацию бактерий в биопленках. Проведенные эксперименты показали, что одним из  механизмов бактерицидного действия фотосенсибилизаторов может быть разрушение мембран бактерий в результате фотодинамического воздействия

ИССЛЕДОВАНИЕ ФОТОСЕНСИБИЛИЗАТОРА ДЛЯ АНТИБАКТЕРИАЛЬНОЙ ФОТОДИНАМИЧЕСКОЙ ТЕРАПИИ НА ОСНОВЕ ЦИКЛОДЕКСТРИНОВОЙ КОМПОЗИЦИИ МЕТИЛОВОГО ЭФИРА 133-N-(N-МЕТИЛНИКОТИНИЛ) БАКТЕРИОПУРПУРИНИМИДА

Cationic bacteriochlorins are promising as antibacterial photosensitizers (PS) for antibacterial photodynamic therapy. Current work is devoted to the study of properties of new nanostructured cationic photosensitizer based on cyclodextrin dispersion of bacteriochlorine derivative – 133-N-(N-methylnicotinyl)-bacteriopurpurinimide methyl ester, for optimization of dispersion composition and selection of time interval between administration of the PS and photodynamic ttherapy of infected septic wounds. Specifics of absorption and fluorescence of PS in dependence of its concentration and proportions of components in dispersion was assessed. Pharmacokinetics and biodistribution of PS were studies in vivo in organs and tissues of intact mice and septic wounds infected with P. аeruginosa or S. aureus. The preliminary studies have shown high efficiency of antimicrobial photodynamic therapy of septic wounds with cyclodextrin dispersion of 133-N-(N-methylnicotinyl)-bacteriopurpurinimide methyl ester. Results of study of absorption and spectral and fluorescence properties of its drug formulation depending on its composition allowed to recommend the use of weight ratio 133-N-(N-methylnicotinyl)bacteriopurpurinimide methyl ester : cyclodextrin about 1:200 and addition of 0,1% Tween 80 to reduce aggregation. The study showed that 133-N-(N-methylnicotinyl)-bacteriopurpurinimide methyl ester was rapidly cleared from mouse blood circulation: more than 70% – for 2 h, 95% – for 1 day, more than 99% – for 6 days. About 98% was cleared from skin and muscles for 6 days. The long-term (up to 24 h) persistence of PS were observed in liver and kidneys, however more than 99% was cleared for 6 days. Thus, it may be supposed that elimination of PS form mice body is through kidneys and liver. After 24 h partial PS aggregation in tissues, particularly in skin and muscles, was observed. Thus, it may be supposed that the reduce of fluorescence intensity after 24 hand later was associated not only with its elimination from body but with its aggregation. Spectral and fluorescence studies showed that 133-N-(Nmethylnicotinyl)-bacteriopurpurinimide methyl ester selectively accumulated in septic wounds, fluorescence contrast was in the range of 3–4. The highest values of concentration and selectivity of its accumulation were achieved at 1.5–3 h after intravenous injection. The irradiation 2 h after injection provided high efficacy of the therapy of septic wounds.Катионные бактериохлорины перспективны как антимикробные фотосенсибилизаторы для антибактериальной фотодинамической терапии. Настоящая работа посвящена изучению свойств нового наноструктурированного катионного фотосенсибилизатора на основе циклодекстриновой дисперсии производного бактериохлорина – метилового эфира 133-N-(N-метилникотинил)бактериопурпуринимида (КБХ), с целью оптимизации состава дисперсии и выбора интервала времени от введения фотосенсибилизатора до проведения фотодинамической терапии инфицированных гнойных ран. Оценены особенности поглощения и флуоресценции фотосенсибилизатора в зависимости от его концентрации и соотношения между компонентами дисперсии. Изучена фармакокинетика и биораспределение фотосенсибилизатора в органах и тканях интактных мышей и гнойных ранах, инфицированных P. аeruginosa или S. aureus. Предварительные исследования показали высокую эффективность антимикробной фотодинамической терапии инфицированных гнойных ран с циклодекстрированной дисперсией КБХ. Проведенные исследования поглощения и спектрально-флуоресцентных свойств его лекарственной формы в зависимости от ее состава позволили рекомендовать использование массового отношения КБХ : циклодекстрин около 1:200 и введение для уменьшения агрегации 0,1% Твин-80. Установлено, что КБХ быстро выводится из кровотока мыши: более 70% – за 2 ч, 95% – за 1 сут , более 99% – за 6 сут. Из кожи и мышц около 98% выводится за 6 сут. Фотосенсибилизатор накапливается и удерживается до 24 ч в печени и почках. Это позволяет предположить, что элиминирование фотосенсибилизатора из организма мышей происходит через почки и печень. Обнаружено, что в тканях, в частности, в коже и мышцах, через 24 ч наблюдается частичная агрегация фотосенсибилизатора. Это позволяет предположить, что уменьшение интенсивности его флуоресценции через 24 и более часа связано не только с его элиминацией из организма, но и с агрегацией. Спектрально-флуоресцентное исследования показали, что КБХ селективно накапливается в инфицированных ранах, флуоресцентная контрастность лежит в пределах 3–4. Наиболее высокие значения концентрации и селективности его накопления в инфицированных ранах были достигнуты через 1,5–3 ч после внутривенного введения. Облучение через 2 ч после введения обеспечило высокую эффективность терапии инфицированных гнойных ран