Ignition of wood subjected to the decreasing radiant energy flux

In this paper we analyze the ignition of wood samples subjected to the decreasing heat flow. The experimental setup was created on the base of the optical wave "Uran-1". The intensity of the heat flow was changed during the experiment by moving the test sample along the optical axis of the elliptic reflector in the setup. Pine wood was used as the test samples. We received the delay times for ignition of pine wood during heating by the decreasing heat flow. The received data were compared with the data for a static heat flow

АНАЛИЗИРУЮЩИЙ МАГНИТ ДЛЯ ТЕХНОЛОГИЧЕСКОГО УСКОРИТЕЛЯ ЭЛЕКТРОНОВ ЛУ-10М

Основной проблемой при использовании магнитов из редкоземельных материалов в ускорительных технологиях является изменение магнитных свойств материала под действием излучения. Особенно актуальна эта задача для мощных технологических ускорителей электронов с энергией до 10 МэВ. Для выбора наиболее стойкого материала были проведены исследования радиационной стойкости образцов магнитов из Sm2Co17 и Nd-Fe-B сплава. Постоянные магниты типа Sm2Co17 и Nd-Fe-B были изгтовлены методом порошковой технологи с использованием PLP процесса в производстве последних. Магнитные образцы подвергались прямому воздействию электронного пучка с энергией 10 МэВ и воздействию тормозного излучения этого пучка. Поглощённая доза от электронов для образцов составляла 16 Град (общий поток электронов, попавший на 1 см2 образца, был равен 1,4х1017) и 160 Град. Активность образцов после облучения изменилась в пределах допустимых норм. Этот факт существенно упрощает использование редкоземельных магнитных материалов в готовых изделиях ускорителей. В процессе облучения магниты охлаждались водой с температурой 38 °С для избежания перегрева. Для оценки изменения величины поля, создаваемого вокруг образца, использовался интеграл интерполированной нормальной к поверхности образца составляющей магнитного поля S по области интерполяции данных в относительных единицах. Для образцов из Nd-Fe-B сплава магнитный поток вокруг образца уменьшился и составил 0,92 и 0,717 от начального значения для указанных доз облучения. Магнитное поле вокруг образцов из Sm2Co17 сплава не изменилось в пределах точности измерений для тех же доз. На основе образцов из Sm2Co17 сплава размерами 30х24х12 мм было проведено моделирование и конструирование магнита для анализа пучка электронов технологического ускорителя на энергию до 10 МэВ. Наибольшее значение поля в медианной плоскости магнита равно 0,3110 Тл. Расстояние между полюсами магнита равно 25,25 мм. Эффективная длина магнита – 33,53 мм. Измеренные параметры поля магнита удовлетворяют заданным при разработке величинам. Магнит также может быть использован для настройки ускорителя в диапазоне энергий до 10 МэВ

Study of e+e−→ppˉe^+e^- \rightarrow p\bar{p} in the vicinity of ψ(3770)\psi(3770)

Using 2917 $\rm{pb}^{-1}$ of data accumulated at 3.773~$\rm{GeV}$, 44.5~$\rm{pb}^{-1}$ of data accumulated at 3.65~$\rm{GeV}$ and data accumulated during a $\psi(3770)$ line-shape scan with the BESIII detector, the reaction $e^+e^-\rightarrow p\bar{p}$ is studied considering a possible interference between resonant and continuum amplitudes. The cross section of $e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}$, $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p})$, is found to have two solutions, determined to be ($0.059\pm0.032\pm0.012$) pb with the phase angle $\phi = (255.8\pm37.9\pm4.8)^\circ$ ($<$0.11 pb at the 90% confidence level), or $\sigma(e^+e^-\rightarrow\psi(3770)\rightarrow p\bar{p}) = (2.57\pm0.12\pm0.12$) pb with $\phi = (266.9\pm6.1\pm0.9)^\circ$ both of which agree with a destructive interference. Using the obtained cross section of $\psi(3770)\rightarrow p\bar{p}$, the cross section of $p\bar{p}\rightarrow \psi(3770)$, which is useful information for the future PANDA experiment, is estimated to be either ($9.8\pm5.7$) nb ($<17.2$ nb at 90% C.L.) or $(425.6\pm42.9)$ nb

Особливості транссфеноїдальних хірургічних втручань з приводу аденоми гіпофіза, що секретує адренокортикотропний гормон

Technical peculiarities of transsphenoidal interventions based on experience of 121 procedures at 107 patients with pituitary adenoma, secreting ACTH, are described. Unilateral transnasal paraseptal transsphenoidal approach was preferable. Permanent clinical remission was achieved at 83 (77,6%) patients.На основании опыта выполнения 121 транссфеноидальной операции у 107 пациентов по поводу аденомы гипофиза, секретирующей адренокортикотропный гормон, описаны технические особенности вмешательства. Предпочтение отдавали одностороннему трансназальному парасептальтому транссфеноидальному хирургическому подходу. После транссфеноидальных вмешательств стойкая клиническая ремиссия достигнута у 83 (77,6%) пациентов.На основі досвіду виконання 121 транссфеноїдальної операції у 107 пацієнтів з приводу аденоми гіпофіза, що секретує адренокортикотропний гормон, описані технічні особливості цих втручань. Перевагу віддавали однобічному трансназальному парасептальному транссфеноїдальному хірургічному підходу. Після транссфеноїдальних втручань стійка клінічна ремісія досягнута у 83 (77,6%) пацієнтів

Endoscopic endonasal surgical management of giant pituitary adenomas with extension into ventricle system

Objective: to estimate the results of endoscopic endonasal surgical management of giant pituitary adenomas (GPAs) with extension into ventricular system (VS), to study the peculiarities of surgical techniques. Materials and methods. 49 adult patients with GPAs with extension into VS were included in the study. The depth of research 2016-2021. This is a consecutive sampling of 1339 pituitary adenomas. GPAs with extension into VS made up 3.66% (49/1339) among all treated pituitary adenomas, and 43.4% among 113 GPAs. Distribution by gender – 18 (36.7%) women and 31 (63.3%) men. Average age was 54.1±11.3 years. Results. The largest consecutive series of GPAs with extension into VS that underwent endoscopic endonasal surgery was analyzed. Gross total resection was achieved in 32.7% (16/49), subtotal – 42.9% (21/49), partial – 12.2% (6/49), contraindications for tumor removal were issued in 12.2% (6/49) cases, these patients underwent extended biopsy and ventriculoperitoneal shunting in 4 patients. In 67.4% (33/49) was admitted visual function improvement. In 12.2% (6/49) vision remained at preoperative level, with no visual impairment. In 20.4% (10/49) of cases, vision deteriorated immediately after surgery. Upon re-examination at 6‒8 weeks in this group, vision returned to baseline in 60% (6/10) of patients. An immunohistochemical study found that 89.8% of the tumors were hormonally inactive. There was allocated a separate group of null cell pituitary adenomas, which accounted for 18.9% of cases. ACTH, LH-FSH, GH, TTH, prolactin secreting PAs were detected in 30.6%, 24.5%, 16.3%, 8.2% and 2.0% respectively. Hypopituitarism was diagnosed in 30.6% (15/49) of patients. Diabetes insipidus was detected for the first time in the postoperative period in 12.2% (6/49) of patients. 14.3% (7/49) of the cases of postoperative cerebrospinal fluid leak were diagnosed. Meningitis developed in 8.1% (4/49). The mortality rate was 6.1% (3/49). Conclusions. An analysis of complications in the early postoperative period found that the incidence of complications in GPAs with extension into VS was statistically significantly higher when compared to the cohort of patients who underwent endoscopic endonasal surgery for pituitary adenomas removal, indicating the complexity of this pathology. Despite the significant increase in the complexity of endoscopic interventions and still considerable threats of postoperative cerebrospinal fluid leak in the opening of the VS, we can already consider endonasal operations in the vast majority of GPAs as the method of choice. A new classification approach to the study group of GPAs was proposed. It allows us to separate the relatively low-risk and high-risk groups of high-flow intraoperative cerebrospinal fluid leak, which is directly correlated with the risks of postoperative complications and mortality in our study. In addition, we emphasize a special, although the smallest group of GPAs with extension into the third ventricle (type 3). Such cases require special attention and the decision to have ventriculoperitoneal shunting before or immediately after the removal of the tumor

Endonasal surgical management of tuberculum sellae meningiomas. Our experience

Purpose: to evaluate the results of endonasal interventions in patients with meningioma of the TS, to determine the criteria for selecting patients for endonasal approach, to establish indications and contraindications, to analyze the radicalism of operations, their technical features and complications associated with this approach. Materials and methods. the indications and contraindications for endonasal surgery of meningioma of the TS, which were performed in Romodanov Neurosurgery Institute from 2014 to 2022. The study includes 32 patients with a diagnosis confirmed by instrumental examinations: meningioma of the TS, who underwent endonasal tumour removal. The results of interventions were evaluated based on the postoperative ophthalmological (with optical coherence tomography - OCT), endocrinological (laboratory), instrumental (CT and MRI) and rhinoscopic follow-up of patients. Results. Performance of endonasal surgery for TS meningioma, method of bony defect plastic surgery, which significantly reduces the percentage of CSF leak was described in our article. Thus, it was confirmed that our percentage of CSF leak (9.4%) was significantly lower compared to other authors. We also assessed radicality of endonasal removal of TS meningioma of the TS. Simpson I was achieved in 87.5%. In 26 patients (81.2%) in the early postoperative period improvement of visual acuity and expansion of visual fields has been noted, which was confirmed by an ophthalmologist's examination and optical coherence tomography. In 4 patients (12.5%) no dynamic of visual disturbances was noted, in 2 patients (6.25%) a slight decrease of visual acuity was noted. Intra- and postoperative complications in patients with TS meningiomas were analyzed. There were no mortality, hemorrhagic complications and postoperative meningitis. Five (15.6%) patients had postoperative hypopituitarism. Two (6.25%) patients had a syndrome of inadequate secretion of antidiuretic hormone, manifested by hyponatremia. Among postoperative complications there were 3 cases of CSF leak (9.38%). One case of CSF leak required reoperation (3.13%). We also observed an overpacking with a fat graft (1 case), which led to decreased visual acuity in the early postoperative period and required reoperation (3.13%). In 6 (18.7%) cases in the postoperative period, anosmia occurred due to the extended approach and traumatization of the nasal mucous membrane. Conclusions. The main complications of endonasal interventions are: intraoperative damage of neurovascular structures, CSF leak, meningitis, necrosis of the nasoseptal flap, hemorrhages in the tumour bed, overpacking with a fat graft which leads to decreased vision in the early postoperative period and anosmia. The rate of major complications described in this article is low and quite acceptable. Critical issues such as meningitis and hemorrhagic complications are completely absent in this study

Features of neuro-ophthalmic symptoms in patients with parasellar meningiomas

Goal. To analyze the features of neuro-ophthalmic symptoms and study visual functions recovery following parasellar meningiomas (PM) surgery. Material and methods. We have analyzed the results of treating 47 patients with PM which have been operated in the Romodanov Neurosurgery Institute in 2017 - 2021. The main group included 47 patients (94 eyes) with PM with visual disorders. Clinical-neurological and ophthalmological examination and a range of neuroimaging studies were carried out. To evaluate the visual functions, the results were analyzed according to the recommendations of the German Ophthalmological Society. Results. Binocular visual disturbances have been detected in 34 (72.3%) patients. Among visual field defects, absolute bitemporal hemianopia prevailed in 14.9% of patients and a combination of relative upper quadrant temporal hemianopia with absolute temporal hemianopia in 19.2% of patients. Monocular visual disturbances have been detected in 13 (27.7%) patients. Optic nerve atrophy was found in 38 patients (80.9%): unilateral - 21 patients (21 eyes), bilateral - 17 patients (34 eyes). A probable difference was revealed in the average visual acuity: before treatment 0.55±0.04, after treatment 0.67±0.04 (p<0.05) and the average total loss of sensitivity: before treatment 11.37±0, 78 dB and after treatment 9.14±0.79 dB (p<0.05). Conclusions. Parasellar meningiomas constitute a significant part of extracerebral tumors. As a result of surgical treatment, there is a significant improvement in visual acuity and visual field

Ignition of wood subjected to the decreasing radiant energy flux

In this paper we analyze the ignition of wood samples subjected to the decreasing heat flow. The experimental setup was created on the base of the optical wave "Uran-1". The intensity of the heat flow was changed during the experiment by moving the test sample along the optical axis of the elliptic reflector in the setup. Pine wood was used as the test samples. We received the delay times for ignition of pine wood during heating by the decreasing heat flow. The received data were compared with the data for a static heat flow