Engineering of Papaya Mosaic Virus (PapMV) Nanoparticles through Fusion of the HA11 Peptide to Several Putative Surface-Exposed Sites

Papaya mosaic virus has been shown to be an efficient adjuvant and vaccine platform in the design and improvement of innovative flu vaccines. So far, all fusions based on the PapMV platform have been located at the C-terminus of the PapMV coat protein. Considering that some epitopes might interfere with the self-assembly of PapMV CP when fused at the C-terminus, we evaluated other possible sites of fusion using the influenza HA11 peptide antigen. Two out of the six new fusion sites tested led to the production of recombinant proteins capable of self assembly into PapMV nanoparticles; the two functional sites are located after amino acids 12 and 187. Immunoprecipitation of each of the successful fusions demonstrated that the HA11 epitope was located at the surface of the nanoparticles. The stability and immunogenicity of the PapMV-HA11 nanoparticles were evaluated, and we could show that there is a direct correlation between the stability of the nanoparticles at 37°C (mammalian body temperature) and the ability of the nanoparticles to trigger an efficient immune response directed towards the HA11 epitope. This strong correlation between nanoparticle stability and immunogenicity in animals suggests that the stability of any nanoparticle harbouring the fusion of a new peptide should be an important criterion in the design of a new vaccine

Mode decomposition of Kerr self-cleaned beams by phase only SLM

Graded-index multimode optical bers have recently attracted a renewed attention, thanks to the discovery of new nonlinear eects, such as Kerr beam self-cleaning. In essence, Kerr self-cleaning involves a ow of the propagating beam energy into the fundamental mode of the ber, accompanied by a redistribution of the remaining energy among high-order modes. Increasing the fundamental mode energy leads to a signicant improvement of the output beam quality. A standard method to determine beam quality is to measure the M2 parameter. However, since self-cleaning involves the nonlinear redistribution of energy among a large number of ber modes, measuring a single beam quality parameter is not sucient to characterize the eect. A properly informative approach requires performing the mode decomposition of the output beam. Mode decomposition permits to evaluate the energy distribution among all of the excited ber modes, which enables investigations of nonlinear mode coupling processes at a qualitatively new level. In this work, we demonstrate an eciency mode decomposition method based on holography, which is suitable for analyzing the self-cleaning eect. In a theoretical study, we describe the solution of the mode decomposition problem for the modes of the gradedindex multimode ber. In an experimental investigation, we demonstrate the decomposition of both low-power (speckled) and self-cleaned beams, involving more than 80 modes

Multicolour nonlinearly bound chirped dissipative solitons

The dissipative soliton regime is one of the most advanced ways to generate high-energy femtosecond pulses in mode-locked lasers. On the other hand, the stimulated Raman scattering in a fibre laser may convert the excess energy out of the coherent dissipative soliton to a noisy Raman pulse, thus limiting its energy. Here we demonstrate that intracavity feedback provided by re-injection of a Raman pulse into the laser cavity leads to formation of a coherent Raman dissipative soliton. Together, a dissipative soliton and a Raman dissipative soliton (of the first and second orders) form a two (three)-colour stable complex with higher total energy and broader spectrum than those of the dissipative soliton alone. Numerous applications can benefit from this approach, including frequency comb spectroscopy, transmission lines, seeding femtosecond parametric amplifiers, enhancement cavities and multiphoton fluorescence microscopy

РАСШИРЕНИЕ ДИНАМИЧЕСКОГО ДИАПАЗОНА АНАЛИЗАТОРОВ МАЭС НА ОСНОВЕ ЛИНЕЕК ФОТОДЕТЕКТОРОВ БЛПП-2000 И БЛПП-4000

One trend in the development of integral atomic emission spectral analysis with low spectral background excitation sources, such as inductively coupled or microwave plasma, is to increase the dynamic range of spectrum recording systems based on photodetector arrays. To achieve low detection limits, it is necessary to use photodetector arrays with low reading noise. The dynamic range of a single readout of such photodetector arrays usually does not exceed four orders of magnitude. The dynamic range increase due to the accumulation of spectra from multiple acquisition leads to a quadratic increase in the measurement time. This method does not allow one to cover the entire dynamic range of spectral line intensities of inductively coupled or microwave plasma (which can reach seven orders of magnitude) while maintaining an acceptable total measurement time of a sample spectrum. As an alternative, it is proposed to increase the dynamic range toward higher line intensities by using two different alternating accumulation times during measurement. The objective of this study is to implement the proposed recording mode in MAES analyzers based on BLPP-2000 and BLPP-4000 photodetector arrays in order to increase the dynamic range of recorded spectral lines. Dependences of the signal-to-noise ratio and the dynamic range of spectral lines recorded in integral atomic emission spectrometry on the accumulation time, the total measurement time, the spectral background level, and the photodetector array parameters are obtained. It is shown theoretically that the use of the recording mode with alternating different accumulation times should increase the dynamic range of BLPP-2000 and BLPP-4000 photodetector arrays by two orders of magnitude. The dynamic range of spectral line intensities of a hollow-cathode lamp is shown experimentally to increase by two orders of magnitude (to five orders of magnitude).Keywords: atomic emission spectrometry, inductively coupled plasma, microwave plasma, spectrum analyzer, MAES, photodetector arrays, extended dynamic range, alternating exposure DOI: http://dx.doi.org/10.15826/analitika.2021.25.4.011Sergey A. Babin1,2, Vladimir A. Labusov1,2,3, Denis O. Selyunin1,2, and Oleg V. Pelipasov1,21Institute of Automation and Electrometry, Siberian Branch of the Russian Academy of Sciences, pr. Akademika Koptyuga, 1, Novosibirsk, 630090, Russian Federation2VMK-Optoelektronika, pr. Akademika Koptyuga, 1, Novosibirsk, 630090,Russian Federation3Novosibirsk State Technical University, pr. K. Marksa, 20, Novosibirsk,630073, Russian FederationОдно из направлений развития метода атомно-эмиссионного спектрального анализа с источниками возбуждения спектров, имеющими низкую интенсивность уровня спектрального фона, таких как индуктивно связанная или микроволновая плазма, является увеличение динамического диапазона систем регистрации спектров на основе линеек фотодетекторов. Для достижения низких пределов обнаружения необходимо использовать линейки с малым значением СКО шума чтения. Динамический диапазон одиночного чтения таких линеек фотодетекторов обычно не превышает четырех порядков. Увеличение динамического диапазона за счет многократной регистрации и накопления спектров приводит к квадратичному росту времени измерения. Такой способ не позволяет перекрыть весь динамический диапазон интенсивностей спектральных линий индуктивно связанной и микроволновой плазмы, который может достигать 7 порядков, при сохранении приемлемого полного времени регистрации спектра образца. В качестве альтернативы предложено увеличение динамического диапазона в сторону регистрации бόльших интенсивностей линий за счёт регистрации спектров в течение времени измерения с попеременным чередованием накоплений двух различных продолжительностей. Цель работы – внедрение предложенного режима в анализаторы МАЭС с линейками фотодетекторов БЛПП‑2000 и БЛПП‑4000 для увеличения динамического диапазона регистрируемых спектральных линий. В работе получены формулы зависимости отношения сигнал-шум и динамического диапазона регистрации спектральных линий в интегральной атомно-эмиссионной спектрометрии в зависимости от продолжительности накопления, полного времени измерения, уровня спектрального фона и параметров линеек. Теоретически показано, что применение режима регистрации с чередованием накоплений различной продолжительности должно увеличить динамический диапазон измерения линеек фотодетекторов БЛПП‑2000 и БЛПП‑4000 на два порядка. Экспериментально показано увеличение динамического диапазона измерения интенсивности спектральных линий лампы полого катода на два порядка до 5 порядков величины.Ключевые слова: атомно-эмиссионная спектрометрия, индуктивно-связанная плазма, микроволновая плазма, анализатор спектров, МАЭС, линейки фотодетекторов, расширенный динамический диапазон, чередование времён экспозицийDOI: http://dx.doi.org/10.15826/analitika.2021.25.4.01

All-fiber highly chirped dissipative soliton generation in the telecom range

A high-energy (0.93 nJ) all-fiber erbium femtosecond oscillator operating in the telecom spectral range is proposed and realized. The laser cavity, built of commercially available fibers and components, combines polarization maintaining (PM) and non-PM parts providing stable generation of highly chirped (chirp parameter 40) pulses compressed in an output piece of standard PM fiber to 165 fs. The results of the numerical simulation agree well with the experiment. The analyzed intracavity pulse dynamics enables the classification of the generated pulses as dissipative solitons

Experimental Method of Temperature and Strain Discrimination in Polymer Composite Material by Embedded Fiber-Optic Sensors Based on Femtosecond-Inscribed FBGs

Experimental method of temperature and strain discrimination with fiber Bragg gratings (FBGs) sensors embedded in carbon fiber-reinforced plastic is proposed. The method is based on two-fiber technique, when two FBGs inscribed in different fibers with different sensitivities to strain and/or temperature are placed close to each other and act as a single sensing element. The nonlinear polynomial approximation of Bragg wavelength shift as a function of temperature and strain is presented for this method. The FBGs were inscribed with femtosecond laser by point-by-point inscription technique through polymer cladding of the fiber. The comparison of linear and nonlinear approximation accuracies for array of embedded sensors is performed. It is shown that the use of nonlinear approximation gives 1.5–2 times better accuracy. The obtained accuracies of temperature and strain measurements are 2.6–3.8°C and 50–83 με in temperature and strain range of 30–120°C and 0–400 με, respectively

High affinity binding of pyrethroids to the � subunit of brain sodium channels

SUMMARY Na ϩ channels are the primary molecular targets of the pyrethroid insecticides. Na ϩ channels consisting of only a type IIA ␣ subunit expressed in Chinese hamster ovary cells responded to pyrethroid treatment in a normal manner: a sustained Na ϩ current was induced progressively after each depolarizing pulse in a train of stimuli, and this Na ϩ current decayed slowly on repolarization. These modified Na ϩ channels could be reactivated at much more negative membrane potentials (V 0.5 ϭ Ϫ139 mV) than unmodified Na ϩ channels (V 0.5 ϭ Ϫ28 mV). These results indicate that pyrethroids can modify the functional properties of the Na ϩ channel ␣ subunit expressed alone by blocking their inactivation, shifting their voltage dependence of activation, and slowing their deactivation. To demonstrate directly the specific interaction of pyrethroids with the ␣ subunit of voltage-gated Na ϩ channels, a radioactive photosensitive derivative, [ 3 H]RU58487, was used in binding and photolabeling studies. In the presence of a low concentration of the nonionic detergent Triton X-100, specific pyrethroid binding to Na ϩ channels in rat brain membrane preparations could be measured and reached 75% of total binding under optimal conditions. Binding approached equilibrium within 1 hr at 4°, dissociated with a half-time of ϳ10 min, and had K D values of ϳ58 -300 nM for three representative pyrethroids. Specific pyrethroid binding was enhanced by ϳ40% in the presence of 100 nM ␣-scorpion toxin, but no allosteric enhancement was observed in the presence of toxins acting at other Na ϩ channel receptor sites. Extensive membrane washing increased specific binding to 89%. Photolabeling with [ 3 H]RU58487 under these optimal binding conditions revealed a radiolabeled band with an apparent molecular mass of 240 kDa corresponding to the Na ϩ channel ␣ subunit. Anti-peptide antibodies recognizing sequences within the ␣ subunit were able to specifically immunoprecipitate the covalently modified channel. Together, these results demonstrate that the pyrethroids can modify the properties of cells expressing only the ␣ subunit of Na ϩ channels and can bind specifically to a receptor site on the ␣ subunit