Electron Spin for Classical Information Processing: A Brief Survey of Spin-Based Logic Devices, Gates and Circuits

In electronics, information has been traditionally stored, processed and communicated using an electron's charge. This paradigm is increasingly turning out to be energy-inefficient, because movement of charge within an information-processing device invariably causes current flow and an associated dissipation. Replacing charge with the "spin" of an electron to encode information may eliminate much of this dissipation and lead to more energy-efficient "green electronics". This realization has spurred significant research in spintronic devices and circuits where spin either directly acts as the physical variable for hosting information or augments the role of charge. In this review article, we discuss and elucidate some of these ideas, and highlight their strengths and weaknesses. Many of them can potentially reduce energy dissipation significantly, but unfortunately are error-prone and unreliable. Moreover, there are serious obstacles to their technological implementation that may be difficult to overcome in the near term. This review addresses three constructs: (1) single devices or binary switches that can be constituents of Boolean logic gates for digital information processing, (2) complete gates that are capable of performing specific Boolean logic operations, and (3) combinational circuits or architectures (equivalent to many gates working in unison) that are capable of performing universal computation.Comment: Topical Revie

Charge inhomogeneities and transport in semiconductor heterostructures with a manganese δ\delta-layer

We study experimentally and theoretically the effects of disorder, nonlinear screening, and magnetism in semiconductor heterostructures containing a $\delta$-layer of Mn, where the charge carriers are confined within a quantum well and hence both ferromagnetism and transport are two-dimensional (2D) and differ qualitatively from their bulk counterparts. Anomalies in the electrical resistance observed in both metallic and insulating structures can be interpreted as a signature of significant ferromagnetic correlations. The insulating samples turn out to be the most interesting as they can give us valuable insights into the mechanisms of ferromagnetism in these heterostructures. At low charge carrier densities, we show how the interplay of disorder and nonlinear screening can result in the organization of the carriers in the 2D transport channel into charge droplets separated by insulating barriers. Based on such a droplet picture and including the effect of magnetic correlations, we analyze the transport properties of this set of droplets, compare it with experimental data, and find a good agreement between the model calculations and experiment. Our analysis shows that the peak or shoulder-like features observed in temperature dependence of resistance of 2D heterostructures $\delta$-doped by Mn lie significantly below the Curie temperature $T_{C}$ unlike the three-dimensional case, where it lies above and close to $T_{C}$. We also discuss the consequences of our description for understanding the mechanisms of ferromagnetism in the heterostructures under study.Comment: 13 pages, 12 figures, RevTe

Enzymatic oligomerization and polymerization of arylamines: state of the art and perspectives

The literature concerning the oxidative oligomerization and polymerization of various arylamines, e.g., aniline, substituted anilines, aminonaphthalene and its derivatives, catalyzed by oxidoreductases, such as laccases and peroxidases, in aqueous, organic, and mixed aqueous organic monophasic or biphasic media, is reviewed. An overview of template-free as well as template-assisted enzymatic syntheses of oligomers and polymers of arylamines is given. Special attention is paid to mechanistic aspects of these biocatalytic processes. Because of the nontoxicity of oxidoreductases and their high catalytic efficiency, as well as high selectivity of enzymatic oligomerizations/polymerizations under mild conditions-using mainly water as a solvent and often resulting in minimal byproduct formation-enzymatic oligomerizations and polymerizations of arylamines are environmentally friendly and significantly contribute to a "green'' chemistry of conducting and redox-active oligomers and polymers. Current and potential future applications of enzymatic polymerization processes and enzymatically synthesized oligo/polyarylamines are discussed

Многоуровневые инъекции ботулинического токсина типа А (Абоботулотоксина) при лечении спастических форм детского церебрального паралича: ретроспективное исследование опыта 8 российских центров

Background: The contemporary application of Botulinum toxin A (BTA) in cerebral palsy (CP) implies multilevel injections both in on-label and off-label muscles. However, there is no single international opinion on the effective and safe dosages, target muscles, and intervals between the injections.Objective: Our aim was to analyze the Russian multicenter independent experience of single and repeated multilevel injections of Abobotulinum toxin А in patients with spastic forms of CP.Methods: 8 independent referral CP-centers (10 hospitals) in different regions of Russia. Authors evaluated intervals between the injections, dosages of the BTA for the whole procedure, for the body mass, for the each muscle, and functional segment of the extremities.Results: 1872 protocols of effective BTA injections (1–14 repeated injections) for 724 patients with spastic CP were included. The age of the patients was between 8 months to 17 years 4 months at the beginning of the treatment (with a mean of 3 years 10 months). Multilevel BTA injections were indicated for the majority (n = 634, 87.6%) of the patients in all the centers. The medians of the dosages for the first BTA injection were between 30–31 U/kg (500 U), the repeated injections doses up to 45 U/kg (1000 U) (in most centers). The median intervals between the repeated injections were 180–200 days in 484 (66.9%) patients and 140–180 days in 157 (24.7%) patients. In 2 centers, children with GMFCS IV–V were injected more often than others.Conclusion: Multilevel BTA injections were indicated for the most patients. The initial dose of Abobotulinum toxin A was 30–31 U/kg. The repeated injections dose could increase up to 40 U/kg. The repeated injections were done in 140–200 days after the previous injection.Современная концепция ботулинотерапии при детском церебральном параличе (ДЦП) предлагает использование многоуровневых инъекций в расширенное число мышц. Однако по-прежнему отсутствует консенсус относительно выбора оптимальных доз, мышц и интервалов между инъекциями.Цель исследования: изучить российский опыт применения однократных и повторных многоуровневых инъекций абоботулотоксина при лечении спастичности у пациентов с ДЦП.Методы: в ретроспективном исследовании проанализирован опыт ботулинотерапии при ДЦПв 8 специализированных центрах России. Изучали протоколы клинически эффективных инъекций. Оценивали общие дозы препарата БТА, дозы на единицу массы тела пациентов, на всю инъекционную сессию и отдельные мышцы, а также интервалы между инъекциями.Результаты: изучено 1872 протокола клинически эффективных инъекций, всего от 1 до 14 повторных инъекций, сделанных 724 пациентам в возрасте от 8 мес до 17 лет 4 мес (медиана возраста на момент первой инъекции БТА — 3 года 10 мес) на момент начала ботулинотерапии. Большинство пациентов (n = 634; 87,6% инъекций) получили многоуровневую ботулинотерапию. Во всех центрах при первичных инъекциях БТА медиана доз находилась в пределах 30–31 Ед/кг массы тела (общая — 500 Ед). При повторных инъекциях в большинстве учреждений максимальные дозы превышали 45 Ед/кг (1000 Ед). Средние интервалы между повторными инъекциями колебались в пределах 140–180 сут для 157 (24,7%) и 180–200 сут для 484 (66,9%) пациентов. В 2 из 8 центров пациенты с наиболее выраженными двигательными нарушениями (GMFCS IV–V) требовали более частых повторных инъекций БТА.Заключение: в специализированных центрах большинству пациентов с ДЦП ботулинотерапию проводили по многоуровневой схеме. Общая доза абоботулотоксина при первичных инъекциях составляла 30–31 Ед/кг; при повторных инъекциях она могла быть увеличена до 40 Ед/кг и более. Вопрос о повторном проведении инъекции БТА рассматривался в интервале 140–200 сут после предшествующей инъекции