Theory of shot noise in space-charge limited diffusive conduction regime

As is well known, the fluctuations from a stable stationary nonequilibrium state are described by a linearized nonhomogeneous Boltzmann-Langevin equation. The stationary state itself may be described by a nonlinear Boltzmann equation. The ways of its linearization sometimes seem to be not unique. We argue that there is actually a unique way to obtain a linear equation for the fluctuations. In the present paper we treat as an example an analytical theory of nonequilibrium shot noise in a diffusive conductor under the space charge limited regime. Our approach is compared with that of Schomerus, Mishchenko and Beenakker [Phys. Rev. B 60, 5839 (1999)]. We find some difference between the present theory and the approach of their paper and discuss a possible origin of the difference. We believe that it is related to the fundamentals of the theory of fluctuation phenomena in a nonequilibrium electron gas.Comment: 17 pages, no figure

Dual application of duckweed and azolla plants for wastewater treatment and renewable fuels and petrochemicals production

Shortages in fresh water supplies today affects more than 1 billion people worldwide. Phytoremediation strategies, based on the abilities of aquatic plants to recycle nutrients offer an attractive solution for the bioremediation of water pollution and represents one of the most globally researched issues. The subsequent application of the biomass from the remediation for the production of fuels and petrochemicals offers an ecologically friendly and cost-effective solution for water pollution problems and production of value-added products. Results: In this paper, the feasibility of the dual application of duckweed and azolla aquatic plants for wastewater treatment and production of renewable fuels and petrochemicals is explored. The differences in absorption rates of the key wastewater nutrients, ammonium and phosphorus by these aquatic macrophytes were used as the basis for optimization of the composition of wastewater effluents. Analysis of pyrolysis products showed that azolla and algae produce a similar range of bio-oils that contain a large spectrum of petrochemicals including straight-chain C10-C21 alkanes, which can be directly used as diesel fuel supplement, or a glycerin-free component of biodiesel. Pyrolysis of duckweed produces a different range of bio-oil components that can potentially be used for the production of "green" gasoline and diesel fuel using existing techniques, such as catalytic hydrodeoxygenation. Conclusions: Differences in absorption rates of the key wastewater nutrients, ammonium and phosphorus by different aquatic macrophytes can be used for optimization of composition of wastewater effluents. The generated data suggest that the composition of the petrochemicals can be modified in a targeted fashion, not only by using different species, but also by changing the source plants' metabolic profile, by exposing them to different abiotic or biotic stresses

Fungal-assisted algal flocculation: Application in wastewater treatment and biofuel production

Background The microalgal-based industries are facing a number of important challenges that in turn affect their economic viability. Arguably the most important of these are associated with the high costs of harvesting and dewatering of the microalgal cells, the costs and sustainability of nutrient supplies and costly methods for large scale oil extraction. Existing harvesting technologies, which can account for up to 50% of the total cost, are not economically feasible because of either requiring too much energy or the addition of chemicals. Fungal-assisted flocculation is currently receiving increased attention because of its high harvesting efficiency. Moreover, some of fungal and microalgal strains are well known for their ability to treat wastewater, generating biomass which represents a renewable and sustainable feedstock for bioenergy production. Results We screened 33 fungal strains, isolated from compost, straws and soil for their lipid content and flocculation efficiencies against representatives of microalgae commercially used for biodiesel production, namely the heterotrophic freshwater microalgae Chlorella protothecoides and the marine microalgae Tetraselmis suecica. Lipid levels and composition were analyzed in fungal-algal pellets grown on media containing alternative carbon, nitrogen and phosphorus sources from wheat straw and swine wastewater, respectively. The biomass of fungal-algal pellets grown on swine wastewater was used as feedstock for the production of value-added chemicals, biogas, bio-solids and liquid petrochemicals through pyrolysis. Co-cultivation of microalgae and filamentous fungus increased total biomass production, lipid yield and wastewater bioremediation efficiency. Conclusion Fungal-assisted microalgal flocculation shows significant potential for solving the major challenges facing the commercialization of microalgal biotechnology, namely (i) the efficient and cost-effective harvesting of freshwater and seawater algal strains; (ii) enhancement of total oil production and optimization of its composition; (iii) nutrient supply through recovering of the primary nutrients, nitrogen and phosphates and microelements from wastewater. The biomass generated was thermochemically converted into biogas, bio-solids and a range of liquid petrochemicals including straight-chain C12 to C21 alkanes which can be directly used as a glycerine-free component of biodiesel. Pyrolysis represents an efficient alternative strategy for biofuel production from species with tough cell walls such as fungi and fungal-algal pellets

Migration as the Main Lever for Economic Development

The article discusses the theoretical and practical role of external labour migration in the development of the national economy of the Republic of Tajikistan. The dynamics of international migration is studied, the experience of regulating migration processes is considered. In addition, the problems and prospects of employment of external labour migrants in developed countries are analysed. Statistical data of the Central Bank of the Russian Federation are summarised to reflect the remittances of Tajik labour migrants, since alternative data are not available in Tajikistan.В статье рассмотрена роль внешней трудовой миграции в развитии национальной экономики Республики Таджикистан. Изучена динамика международной миграции, опыт регулирования миграционных процессов. Кроме того, рассмотрены проблемы и перспективы трудоустройства внешних трудовых мигрантов в развитых странах. Обобщены статистические данные Центрального банка РФ, для того чтобы отразить денежные переводы таджикских трудовых мигрантов, поскольку альтернативных данных в Таджикистане не имеется

Фотобиомодуляция острого болевого синдрома после септопластики

The paper evaluates the effectiveness of the use of therapeutic laser exposure (photobiomodulation therapy – PBMT) to minimize acute pain in the early postoperative period in patients after septoplasty. The study included two groups of patients. Patients of the first group (31 patients) underwent septoplasty with standard management in the postoperative period. Patients of the second group (31 patients) also underwent septoplasty, and then added PBMT to the standard measures of the postoperative period at 3, 6 and 24 h after septoplasty (λ = 0.890 μm, P = 10 W, 2 min) and then intranasally 48 h after septoplasty (λ = 0.630 μm, P = 8 W, 2 min). In patients of both groups, heart rate variability and pain were assessed using a visual analog scale within 48 hours after septoplasty. In patients of the second group, after the use of PBMT, the indicators of heart rate variability had a significantly lower total power, compared with patients of the first group. So, after PBMT, the ultra-low-frequency component of the spectral analysis of heart rate variability in the first group was 18580 ± 2067 ms2, which is significantly higher than in the second group (8086 ± 3003 ms2) (p <0.001). The low-frequency component of heart rate variability was also significantly higher in the first group (1871 ± 405 ms2) compared to the second (1095 ± 190 ms2) (p <0.005), which indicates an increase in the tension of the sympathetic part of the autonomic nervous system in the group without the use of PBMT. In the first 3 hours after surgery, the severity of pain between the groups did not differ significantly (p = 0.07). In the period from 6 to 24 hours after surgery, patients who did not undergo PBMT experienced significantly higher pain than patients with PBMT (p <0.001). Thus, in our study, the group of patients with PBMT showed better results in pain and heart rate variability compared to the classical rehabilitation of patients after septoplasty.В работе оценена эффективность фотобиомодуляционной терапии (ФБМТ) для минимизации острого болевого синдрома в раннем постоперационном периоде у пациентов после проведения септопластики. В исследование были включены две группы наблюдения в количестве 31 пациент каждая. В первой группе была проведена септоплатика со стандартным ведением в послеоперационном периоде. Во второй группе к стандартным мероприятиям послеоперационного периода добавляли ФБМТ через 3, 6 и 24 ч после септопластики (λ=0,890 мкм, P=10 Вт, 2 мин) и далее интраназально через 48 ч после операции (λ=0,630 мкм, P=8 Вт, 2 мин). В обеих группах оценивали вариабельность сердечного ритма (ВСР) и болевой синдром при помощи визуально-аналоговой шкалы в течение 48 ч после септопластики. У пациентов второй группы на фоне применения ФБМТ показатели ВСР имели значимо меньшую общую мощность по сравнению с пациентами первой группы. После проведения ФБМТ ультранизкочастотный компонент спектрального анализа ВСР в первой группе составил 18580±2067 мс2, во второй группе – 8086±3003 мс2 (p<0,001). Низкочастотный компонент ВСР также был значимо выше в первой группе: 1871±405 мс2 и 1095±190 мс2 соответственно (p<0,005), что свидетельствует о повышении напряжения симпатического отдела вегетативной нервной системы в группе без применения ФБМТ. В первые 3 ч после септоплатики интенсивность боли между группами не имела достоверных различий (p=0,07). В период от 6 до 24 ч после хирургического вмешательства пациенты, которым не проводилась ФБМТ, испытывали более интенсивную боль, чем пациенты второй группы (p<0,001). Таким образом, в нашем исследовании группа пациентов с ФБМТ показала лучшие результаты по выраженности болевого синдрома и ВСР по сравнению с классической реабилитацией пациентов после септопластики

Low-energy electronic states of carbon nanocones in an electric field

«Non v’è salvezza al di fuori del mostruoso»; «la diserzione, intrinseca alla letteratura, diventa nel fantastico sfida blasfema, obiezione, tradimento»: in questi passi, lo scrittore italiano Giorgio Manganelli (1922-1990) riafferma la portata trasgressiva della sua opera, indicando nel superamento dei limiti razionali, del verosimile, dell’accettabile o, in altre parole, del narrabile la via per sottrarre la letteratura ad una funzione strumentale. Così, nel privilegiarla come atto di linguaggio e nel disimpegnarla da mansioni mimetico-realistiche, Manganelli la popola di esseri informi e metamorfici. Ad esempio, in opere quali Hilarotragoedia (1964) e Dall’inferno (1985) il mostruoso non si presenta come qualcosa di aberrante, ma piuttosto come il risultato di una sorta di teologia paradossale, in grado di sovvertire o burlare le grandi convenzioni umane. Partendo da tali questioni, l’articolo affronterà il tema del mostro quale infrazione e sovversione essenziali allo scardinamento di un orizzonte ermeneutico antropocentrico, come voleva, tra gli altri, Foucault. «There is no salvation beyond the monstrous»; «desertion, intrinsic to literature, becomes in the Fantastic a blasphemous challenge, objection and betrayal»: with these words, the Italian writer Giorgio Manganelli (1922-1990) reaffirms the transgression of his work. With the overcoming of rational limits, of the plausible, of the acceptable or, in other words, of the tellable, the writer illustrates the way to prevent the use of literature as an instrumental function. Therefore, by using literature as an act of speech and by disengaging it from its mimetic-realistic responsibilities, Manganelli populates it with shapeless and metamorphic beings. In works such as Hilarotragoedia (1964) and From Hell (1985), for example, the monstrous does not resemble something aberrant, but rather it represents a kind of paradoxical theology, capable of subverting or mocking the great human convictions. Starting from these questions, this paper will approach the subject of the monster as infringement and subversion essential for the disruption of a hermeneutic and anthropocentric horizon, as Foucault, among others, wished

Growth of large-area single- and bi-layer graphene by controlled carbon precipitation on polycrystalline Ni surfaces

We report graphene films composed mostly of one or two layers of graphene grown by controlled carbon precipitation on the surface of polycrystalline Ni thin films during atmospheric chemical vapor deposition(CVD). Controlling both the methane concentration during CVD and the substrate cooling rate during graphene growth can significantly improve the thickness uniformity. As a result, one- or two- layer graphene regions occupy up to 87% of the film area. Single layer coverage accounts for 5-11% of the overall film. These regions expand across multiple grain boundaries of the underlying polycrystalline Ni film. The number density of sites with multilayer graphene/graphite (>2 layers) is reduced as the cooling rate decreases. These films can also be transferred to other substrates and their sizes are only limited by the sizes of the Ni film and the CVD chamber. Here, we demonstrate the formation of films as large as 1 in2. These findings represent an important step towards the fabrication of large-scale high-quality graphene samples

Spin-magnetophonon level splitting in semimagnetic quantum wells

Spin-magnetophonon level splitting in a quantum well made of a semimagnetic wide gap semiconductor is considered. The semimagnetic semiconductors are characterized by a large effective $g$ factor. The resonance conditions $\hbar\omega_{\rm LO}=\mu_BgB$ for the spin flip between two Zeeman levels due to interaction with longitudinal optical phonons can be achieved sweeping magnetic field $B$. This condition is studied in quantum wells. It is shown that it leads to a level splitting that is dependent on the electron-phonon coupling strength as well as on the spin-orbit interaction in this structure. We treat in detail the Rashba model for the spin-orbit interaction assuming that the quantum well lacks inversion symmetry and briefly discuss other models. The resonant transmission and reflection of light by the well is suggested as a suitable experimental probe of the level splitting