Multiexcitons confined within a sub-excitonic volume: Spectroscopic and dynamical signatures of neutral and charged biexcitons in ultrasmall semiconductor nanocrystals

The use of ultrafast gating techniques allows us to resolve both spectrally and temporally the emission from short-lived neutral and negatively charged biexcitons in ultrasmall (sub-10 nm) CdSe nanocrystals (nanocrystal quantum dots). Because of forced overlap of electronic wave functions and reduced dielectric screening, these states are characterized by giant interaction energies of tens (neutral biexcitons) to hundreds (charged biexcitons) of meV. Both types of biexcitons show extremely short lifetimes (from sub-100 picoseconds to sub-picosecond time scales) that rapidly shorten with decreasing nanocrystal size. These ultrafast relaxation dynamics are explained in terms of highly efficient nonradiative Auger recombination.Comment: 5 pages, 4 figures, to be published in Phys. Rev.

РЕЗУЛЬТАТЫ ЭТАПНОГО ХИРУРГИЧЕСКОГО ЛЕЧЕНИЯ ИНФАНТИЛЬНЫХ И ЮВЕНИЛЬНЫХ СКОЛИОЗОВ С ИСПОЛЬЗОВАНИЕМ РАЗЛИЧНЫХ МЕТОДИК

Introduction. The analysis Results of surgical treatment of growing children with infantile and juvenile scoliosis (IS) can the optimal method of treatment select. In young children with significant growth potential spinal fusion may not be the best option as it limits further longitudinal growth of the spine and may to the thoracic insufficiency syndrome result. To address this problem recently several techniques focused, their have advantages and drawbacks.Material and methods. Since 2008 year 127 patients (64 girls, 63 boys) aged (4.5 ± 2.1) years were operated on. In group I 65 patients were operated on using VEPTR (Vertical Expandable Prosthetic Titanium Rib) instrumentation, in group II 42 patients using various spinal instrumentation. 20 patients with congenital kyphosis were excluded. The average follow-up time was (5.6 ± 1.1) years.Results. In group I average value of the primary scoliotic curve before surgery was (74.7 ± 22.9), secondary curve (42.8 ± 16.0), thoracic kyphosis (46.3 ± 27.4), lumbar lordosis (54.6 ± 14). Average value of the primary scoliotic curve after surgery was reduced to (51 ± 20) (correction 31.7%), at followup to (56.5 ± 18.5), secondary curve (31.8 ± 12.8) (25.7%), at follow-up to (32.4 ± 18.4), thoracic kyphosis (36.8 ± 20.8) (20,5%), at follow-up to (41.8 ± 21.0), lumbar lordosis (45.4 ± 12.7) (16,9%), at follow-up to (48.2 ± 11.7) (p < 0.05). Space available for lung before surgery was (84.5 ± 8.7) %, after surgery was (94.8 ± 6.7)%, at follow-up increased to (98.6 ± 5.4) % (p < 0.05). Complications included 11 implant dislocations and 1 infection. In group II average value of the primary scoliotic curve before surgery was (87.6 ± 6.6), secondary curve (47.8 ± 4.6), thoracic kyphosis (61.4 ± 10.4), lumbar lordosis (61.8 ± 4.9). Average value of the primary scoliotic curve after surgery was reduced to 50.6 ± 5.3 (correction 42.3%), at follow-up to (66.1 ± 6.3), secondary curve (24.1 ± 2.9) (49.6%), at follow-up to (37 ± 5.4), thoracic kyphosis (38.8 ± 7.7) (36.8%), at follow-up to (59.4 ± 11.2), lumbar lordosis (47.5 ± 4.1) (23.2%), at follow-up to (64.5 ± 4.5) (p < 0.05). Complications included 23 implant dislocations and 1 infection. No neurological complications.Conclusion. Stage correction fusions using various instrumentation is a method of choice for controlled correction of growing children with IS.Введение. Анализ результатов хирургического лечения сколиотических деформаций позвоночника у активно растущих детей позволяет выбрать оптимальный метод лечения. Стабилизация позвоночника является быть оптимальным вариантом, так как может привести к ограничению его дальнейшего роста и развитию синдрома торакальной недостаточности. На решение этой задачи в последнее время ориентировано несколько методик, имеющих свои достоинства и недостатки.Цель исследования – проанализировать результаты хирургического лечения инфантильных и ювенильных сколиозов с использованием различного инструментария.Материал и методы. В период с 1998 по2014 г. оперировано 127 детей (64 девочки и 63 мальчика) с инфантильными и ювенильными деформациями позвоночника различной этиологии. Операции проводились по двум методикам: первая группа (65 больных) – по методике VEPTR (Vertical Expandable Prosthetic Titanium Rib, США), вторая (42 больных) – с использованием дорсального сегментарного инструментария. Средний возраст начала лечения составил (4,5 ± 2,1) года (I группа), (7,6 ± 2,4) года (II группа). Сроки послеоперационного наблюдения составили (5,6 ± 1,1) года (от 6 мес до 12 лет).Результаты. В группе I средняя величина основной сколиотической дуги перед началом лечения составляла (74,7 ± 22,9)°, противоискривления – (42,8 ± 16)°, грудного кифоза – (46,3±27,4)°, поясничного лордоза – (54,6 ± 14)°. Величина основной сколиотической дуги после операции составляла (51,0 ± 20,0)° (коррекция 31,7%), противоискривления – (31,8 ± 12,8)° (коррекция 25,7%), кифоза – (36,8 ± 20,8)° (коррекция 20,5%), лордоза – (45,4 ± 12,7)° (коррекция 16,9%) (p < 0,05). В конце срока наблюдения величина основной сколиотической дуги составила (56,5 ± 18,5)°, противоискривления – (32,4 ± 18,4)°, кифоза – (41,8 ± 21,0)°, лордоза – (48,2 ± 11,7)° (p < 0,05). При использовании инструментария VEPTR отмечено увеличение отношения пространств доступных для легких в сравнении с исходным – (84,5 ± 8,7), послеоперационным – (94,8 ± 6,7) и значением в конце срока наблюдения – (98,6 ± 5,4) (p < 0,05). У 11 пациентов отмечена нестабильность захватов инструментария, 1 случай нагноения. Во II группе средняя величина основной сколиотической дуги перед началом лечения составляла (87,6 ± 6,6)°, противоискривления – (47,8 ± 4,6)°, грудного кифоза – (61,4 ± 10,4)°, поясничного лордоза – (61,8 ± 4,9)°. Величина основной сколиотической дуги после операции составляла (50,6 ± 5,3)° (коррекция 42,3%), противоискривления – (24,1 ± 2,9)° (коррекция 49,6%), кифоза – (38,8 ± 7,7)° (коррекция 36,8%), лордоза – (47,5 ± 4,1)° (коррекция 23,2%) (p < 0,05). В конце срока наблюдения величина основной сколиотической дуги составила (66,1 ± 6,3)°, противоискривления – (37,0 ± 5,4)°, кифоза – (59,4 ± 11,2)°, лордоза – (64,5 ± 4,5)° (p < 0,05). У 23 пациентов отмечена нестабильность захватов инструментария, 1 случай нагноения. Неврологических осложнений не отмечено.Вывод. При хирургическом лечении инфантильных и ювенильных сколиозов методом выбора являются этапные коррекции с использованием различного инструментария

Структурно-функциональные особенности деформации позвоночника при нейрофиброматозе NF-1

To study pathogenetic mechanisms of the development of spinal deformity in neurofibromatosis.Structural components of the spine were presented as specimens obtained after surgical correction of spinal deformity performed in 10 children with III—IV grade scoliosis associated with neurofibromatosis.Etiologic factor of the development of spinal deformity in neurofibromatosis is a mutation of the NF-1 gene in cells of ganglious lamella. Migration of cells carrying mutant gene into one of the sclerotome zones results in oncogene activation and intensive proliferation of chondro-, osteo-, and fibroblasts in the growth plate, intervertebral disc, and vertebral body.Progressive development of the spinal deformity after surgical intervention is accounted both for proliferation of chondro- and fibroblasts in the vertebral body and intervertebral disc and for disturbance of the NF-1 and lumican genes expression.Представлено изучение патогенетических механизмов формирования деформации позвоночника при нейрофиброматозе.Исследованы структурные компоненты позвоночника, полученные в ходе коррекции деформации от 10 детей с III— IV степенью сколиоза на почве нейрофиброматоза.Этиологическим фактором формирования деформации позвоночника при нейрофиброматозе является мутация в клетках ганглиозной пластинки гена NF-1. Миграция клеток, несущих мутантный ген в одну из зон склеротома, приводит к активации онкогена и интенсивной пролиферации хондро-, остео- и фибробластов в пластинке роста, межпозвонковом диске и теле позвонка.Продолженный процесс деформации позвоночника после оперативного вмешательства объясняется пролиферацией хондро- и фибробластов в теле позвонка и межпозвонковом диске и нарушением экспрессии генов люмикана и NF-1

Phenomenological description of the microwave surface impedance and complex conductivity of high-TcT_c single crystals

Measurements of the microwave surface impedance $Z_s(T)=R_s(T)+iX_s(T)$ and of the complex conductivity $\sigma_s(T)$ of high-quality, high-$T_c$ single crystals of YBCO, BSCCO, TBCCO, and TBCO are analyzed. Experimental data of $Z_s(T)$ and $\sigma_s(T)$ are compared with calculations based on a modified two-fluid model which includes temperature-dependent quasiparticle scattering and a unique temperature variation of the density of superconducting carriers. We elucidate agreement as well as disagreement of our analysis with the salient features of the experimental data. Existing microscopic models are reviewed which are based on unconventional symmetry types of the order parameter and on novel mechanisms of quasiparticle relaxation.Comment: 15 pages, 17 figures, 1 tabl

Nitric Oxide Releasing Materials Triggered by Near-Infrared Excitation Through Tissue Filters

Novel materials for the phototherapeutic release of the bioregulator nitric oxide (nitrogen monoxide) are described. Also reported is a method for scanning these materials with a focused NIR beam to induce photouncaging while minimizing damage from local heating. The new materials consist of poly(dimethylsiloxane) composites with near-infrared-to-visible upconverting nanoparticles (UCNPs) that are cast into a biocompatible polymer disk (PD). These PDs are then impregnated with the photochemical nitric oxide precursor Roussin's black salt (RBS) to give UCNP_RBS_PD devices that generate NO when irradiated with 980 nm light. When the UCNP_RBS_PD composites were irradiated with NIR light through filters composed of porcine tissue, physiologically relevant NO concentrations were released, thus demonstrating the potential of such devices for minimally invasive phototherapeutic applications

MORPHOLOGY OF TUBERCULOSIS CONCURRENT WITH HIV INFECTION: POSTMORTEM DATA

The pathomorphology of tuberculosis was studied in 129 deceased patients with concomitant HIV infection and in 50 patients with acutely progressive forms of the disease (a comparison group). In tuberculosis concurrent with HIV infection, the morphological pattern in the lung and other viscera depends on the primacy of a lesion and reflects the progressive pattern of specific inflammation. In the TB-HIV group, the signs of a pre-existing specific process with foci of fibrosis and hyalinosis, a mild or moderate granulomatous reaction with epithelioid cells always persist in the lung. The tuberculous process progresses due to lymphohematogenic and bronchogenic dissemination. The HIV-TB group is characterized by the preponderance of exudative and alterative changes, the absence of signs of separation and organization of inflammatory pyonecrotic foci having no signs of specificity in the lung and other viscera. Progression of tuberculous inflammation occurs mainly by hematogenic dissemination. In all the observed groups, there is lymphadenopathy that appears as caseuos necrosis in the TB-HIV group and reactive hyperplasia in the HIV-TB group

The Mode of Inheritance of Scheuermann’s Disease

The mode of Scheuermann’s disease inheritance and its phenotypic traits in probands and their relatives were studied in 90 pedigrees (90 probands and 385 relatives). The disorder was identified as a genetically related pathology inherited by autosomal dominant type, controlled by a mutant major gene, as a kyphotic deformity without signs of vertebral bodies’ anomaly and torsion. Morphological and biochemical studies showed disturbance in the structure of vertebral growth plate anterior aspects at the level of deformity, defects in proliferation and differentiation of chondrocytes, and change in proteoglycan spectrum in cells and matrix. Twelve candidate genes were studied in chondrocytes isolated from vertebral growth plates of patients with Scheuermann’s disease. The study results included disorder in the IHH gene expression and preservation of the expression of PAX1, two aggrecan isoforms, link protein, types I and II collagen, lumican, versican, growth hormone and growth factor receptor genes, and proliferation gene. Preservation of the SOX9 gene (transcription gene) probably indicates posttranscriptional genetic disorders. The study is under way