Physicomechanical characterization and wood machining from 10 12-year-old Hevea progeny clones with potential for furniture

The objective of this work was to evaluate the physical, mechanical, and wood machining properties of 10 clonal progenies with 12 years of age aiming to produce furniture. A total of 10 progenies and three trees per progenies were used, totalling 30 trees analyzed. The basic density ranged from 0.404 g.cm-3 (IAC 301) to 0.495 g.cm-3 (IAC 326), being it considered a light wood. The anisotropy coefficient values ranged from 1.05 (IAC 40) to 1.68 (PB 330) considered low to medium dimensional instability allowing the use of wood to produce furniture with low dimensional movements. In the compression test most clones fall under class C30. For MOR and MOE, it was observed greater values for IAC 326 (11666 MPa) and GT1 (9575 MPa). In wood machining tests, slightly raised large and few defects on the surface, being them considered easy to work. The results obtained for Hevea brasiliensis, 12 years old, allow us to affirm that wood from a younger age is an alternative for furniture production and will consequently contribute to the reduction of the exploitation and degradation of native forests in Brazil for this purpose.

Evaluation of peripheral amyloid neuropathy

Symptoms of peripheral nervous system (PNS) damage are common clinical manifestations of systemic amyloidosis. Peripheral amyloid neuropathy is characterized by a progressive course, leading to the disability of patients; however, the current possibilities of pathogenetic therapy make the early diagnosis of amyloid neuropathy particularly urgent.Objective: to evaluate the informative value of laser confocal microscopy (LCM) of the cornea in diagnosing small fiber neuropathy of peripheral nerves in patients with systemic amyloidosis.Patients and methods. The study included nine patients (three men and six women) with morphologically confirmed primary amyloidosis (ALamyloidosis) and 12 patients (three men and nine women) with hereditary transthyretin amyloidosis (TTR-amyloidosis) verified by genetic and morphological methods. At baseline, the mean age of patients with AL-amyloidosis was 60.6±10.7 years, with hereditary TTR-amyloidosis – 57.1±13.1 years. According to the history of the disease in AL-amyloidosis, the mean duration of clinical symptoms was 2.7±1.4 years, with TTR-amyloidosis – 5.5±3.6 years. 20 age- and sex-adjusted healthy volunteers were included in the control group. All patients underwent a clinical neurological examination with an assessment of the severity of neuropathy according to the Neuropathy Impairment Score (NIS); 21 patients with systemic amyloidosis and all volunteers of the control group underwent LCM of the corneal nerve fibers (CNF). The coefficients of anisotropy (КΔL) and orientation symmetry (Ksym) of the CNF were calculated to assess the severity of damage to the corneal nerves.Results and discussion. Clinical neurological examination in patients with AL-amyloidosis revealed polyneuropathic syndrome (45%), tunnel syndrome (22%), their combination (22%), and autonomic dysfunction in the form of orthostatic hypotension and impaired motility of the gastrointestinal tract (GI tract; 56%). Symptoms in patients with TTR-amyloidosis were characterized by a combination of tunnel neuropathy and sensory-motor polyneuropathy (50%), distal symmetric polyneuropathy (42%). Frequent symptoms of PNS damage in systemic amyloidosis include autonomic neuropathy (56% – in AL-amyloidosis, 92% – in TTR-amyloidosis) presenting with orthostatic hypotension, impaired gastrointestinal motility, hypohidrosis, and dysuria. The mean NIS score, which characterizes the severity of somatic neuropathy, was significantly higher in patients with TTR-amyloidosis than AL-amyloidosis (p<0.02). LCM of the cornea showed disturbances in the course and structure of the corneal nerve fibers in all examined patients with systemic amyloidosis. The mean anisotropy coefficient values were lower in patients with systemic amyloidosis than in the control group. There were no significant differences in the AL- and TTR-amyloidosis groups. An inverse correlation of average strength between the values of the anisotropy coefficient and NIS was revealed (r=-0.6; p=0.04) in the group of patients with TTR-amyloidosis.Conclusion. Clinical polymorphism of peripheral somatic and autonomic nervous systems lesions is typical for patients with systemic amyloidosis. LCM of the cornea is informative in the diagnosis of small fibers neuropathy of peripheral nerves in systemic amyloidosis; however, it cannot establish the nosology of neuropathy.

Fracability Evaluation Method and Influencing Factors of the Tight Sandstone Reservoir

Fracability evaluation is the basis of reservoir fracturing and fracturing zone optimization. The tight sandstone reservoir is characterized by low porosity and low permeability, which requires hydraulic fracturing to improve industrial productivity. In this study, a systematic model was proposed for the fracability evaluation of tight sandstone reservoirs. The rock mechanics tests and sonic tests demonstrated that tight sandstone reservoir is characterized by high brittleness, high fracture toughness, and weak development of natural fractures. Numerical simulation was used to analyze the change of reservoir parameters during hydraulic fracturing and the influence of in situ stress on fracture propagation. The results showed that when the horizontal stress anisotropy coefficient is small, natural fractures may lead hydraulic fractures to change direction, and complex fracture networks are easily formed in the reservoir. The horizontal stress anisotropy coefficient ranges from 0.23 to 0.52, and it is easy to produce fracture networks in the reservoir. A new fracability evaluation model was established based on the analytic hierarchy process (AHP). The fracability of tight sandstone reservoir is characterized by the fracability index (FI) and is divided into three levels. Based on the model, this study carried out fracability evaluation and fracturing zone optimization in the study area, and the microseismic monitoring results verified the accuracy of the model.

State of corneal nerve fibers after phacosurgery

The question of potential changes in CNF induced by phacosurgery remains poorly understood. The need for research in this direction is dictated by a number of circumstances: the introduction into clinical practice of confocal microscopy of the cornea, the need for phacosurgery against the background of changes in the cornea of various genesis, the possibility of the negative impact of laser radiation in the process of hybrid (femtolaser) phacoemulsification. Purpose. Assessment of changes in CNF after various methods of microinvasive phacosurgery. Material and methods. The studies were conducted in two groups of patients aged 50 to 60 years who underwent standard ultrasound and hybrid PV (30 operations each, respectively). The algorithm for assessing the state of the nerve fibers of the cornea included laser confocal microscopy using original software. To quantify the state of nerves, two coefficients were used: directivity anisotropy (K Δ L) and directivity symmetry (Ksym). Results. Regardless of the operation methodology, a tendency toward a decrease in the directivity anisotropy coefficient and an increase in the directivity symmetry coefficient, conditionally comparable with previously identified age-related changes in nerve fibers, was noted. After hybrid phacoemulsification, a decrease in the directivity anisotropy coefficient 2–2.5 months after the intervention turned out to be statistically less significant compared to the standard ultrasound technique. Further research should be aimed at analyzing the long-term results of both microinvasive phacosurgery techniques and the “classical” extracapsular cataract extraction, which still remains the method of choice in a number of clinical situations. Key words: corneal nerve fibers, phacosurgery, in vivo laser microscopy.

Landslide hazard zones determination on open pit mine edge by circular seismic sounding method

Herein there is an algorithm and method of processing the experimental data obtained by a circular seismic sounding method that makes it possible to increase accuracy in determining an anisotropy coefficient of the ground mechanical properties. The coefficient value is mutually related to the deformation processes at the initial stages of landslide formation. There are results of data processing of the field seismic studies of the adjacent ground at the Angrenskiy coal mine that allow establishing boundaries for the potentially landslide-prone zones, as well as a numerical criterion to predict rock stability under the given conditions.

Effect of the initial austenitization temperature on the structural microheterogeneity during drawing of carbon steel with a pearlite structure

During wire production, strain fields can be distributed inhomogeneously over the section during drawing and cause structural micro-inhomogeneity, which significantly affects the stability of the process. However, during plastic deformation of carbon steel with a pearlite structure, the interlamellar spacing in the ferrite-carbide mixture and the size of pearlite colonies, which determine the deformation behavior of steel, are of great importance. In addition, in the wire manufacturing technology, heat treatment operations are used with heating the steel to the austenitic state, the temperature of which significantly affects the formation of the structure and properties of the steel. The paper investigates the effect of the austenitization temperature on the structural microheterogeneity of a wire made of carbon steel with a pearlite structure after drawing. The results of studying the microstructure, determining the interlamellar spacing, the anisotropy coefficient of pearlite colonies, as well as the distribution of microhardness over the cross section of the sample during drawing after different temperatures of preliminary austenitization are presented. It is shown that after preliminary austenitization at temperatures of 900, 950 and 1000 °C in a wire made of carbon steel with a pearlite structure, microstructural inhomogeneity in the dispersion of the ferrite-pearlite mixture is observed. It manifests itself as a difference of the interlamellar spacing in pearlite at the surface and in the center of the sample cross section and is retained during subsequent drawing with a total reduction of 8 to 15%. It has been established that the temperature of preliminary austenitization has practically no effect on the anisotropy coeffi cient of pearlite colonies in the initial state after austenitization, and it does not change over the cross section of the sample. However, with subsequent drawing with an increase in the total reduction, the anisotropy coefficient increases, while it increases from the surface to the center of the sample. It is revealed that with an increase in the preliminary austenitization temperature from 900 to 1000 °C, the microstructural inhomogeneity in the drawn wire is manifested to a greater extent, which can be associated with an increase in the grain size of the initial austenite, the size of pearlite colonies, and the interlamellar spacing in pearlite. Microstructural inhomogeneity is confirmed by the nature of the distribution of microhardness over the cross section of the sample. The research was carried out with the financial support of the Russian Foundation for Basic Research and DNT within the framework of the scientific project No. 18-58-45008 IND_a.

Determination of the Forming Limit for a ZIRLO™ Sheet with High Anisotropy

In this study, the experimental two-dimensional forming limit diagram (FLD) data for a ZIRLO™ sheet, which is used in nuclear fuel rod support grids, were converted and presented as a triaxiality failure diagram (TFD). Most previous studies assumed ZIRLO™ to be isotropic when calculating the effective stress and strain. However, for highly anisotropic materials, the anisotropy should be considered for calculations of effective stress and strain; hence, in this study, they were calculated by introducing the normal anisotropy coefficient. To obtain this parameter of the ZIRLO™ specimens, tensile tests were performed on specimens with 0°, 45°, and 90° angles with respect to the rolling direction. It was observed that the average normal anisotropy coefficient measured during the tests was 4.94, which is very high. The von Mises isotropic and Hill 48 anisotropic yield criterion were applied to the FLD data that were experimentally determined using a limit dome height test and were converted into effective stress and effective strain. When the FLD is converted to TFD, the curve will increase in the top-right direction if the r-value is greater than 1, and this become more severe as the r-value increases. The TFD, which was converted considering the anisotropy, is almost the same to the TFD obtained using the digital image correlation method in the tensile tests of four specimens with different stress states. If anisotropy is not considered, then the formability is normally underestimated. However, a highly accurate TFD can be obtained with the method proposed in this study.

Characterization of properties and deterioration by termites in the Pinus elliottii Engelm. wood

The technological properties of wood are constituted by parameters, which after being analyzed, make it possible to define an appropriate use for this material. However, the deterioration of the wood due to the attack of termites, which find their food source in the chemical components, ends up altering these original technological characteristics, reducing their useful life and compromising their use. Thus, this study aimed to determine some technological properties of Pinus elliottii, as well as to evaluate the influence of deterioration caused by Nasutitermes termites in this wood. Specimens with dimensions of 20 x 20 x 150 mm (tangential x radial x longitudinal) were used as specimens. The physical properties evaluated were the basic density and linear shrinkage (tangential and radial contractions, and anisotropy coefficient), while the mechanical properties were represented through the Janka hardness test and compression parallel to the fibers. After 40 days of the biodeterioration test with Nasutitermes termites, changes in the equilibrium moisture content, retractability, water absorption rate and mechanical properties were evaluated. While the physical and mechanical properties evaluated showed values similar to those found in the literature, the deterioration caused by termites caused a reduction in hardness and parameters related to compression, increasing the dimensional instability of the wood, represented by the variation in the anisotropy coefficient. This made it possible to conclude that the biodeterioration resulting from the attack of termites directly affected the technological parameters of the wood, and consequently, its quality for the use in the purpose it could initially be destined.

Study of thin layered reservoirs with toroidal sources and receivers (on the example of the Priobskoe oil field)

On the example of the Priobskoye oil field of the West Siberian oil and gas province, we show the relevance of studying thin-layered oil-saturated reservoirs, as well as consider the corresponding world experience. The operating principle of a probe system with toroidal sources and receivers is described, after which we perform 2D finite-difference simulation and analysis of its signals in typical geoelectric reservoir models. The dependence of the signals on the resistivity anisotropy coefficient is demonstrated. In realistic geoelectric sections of the Priobskoye field, obtained by numerical inversion of BKZ field data, 2D finite-difference simulation for the system with toroids is conducted. It implies the fundamental possibility of investigating thin-layered electrically anisotropic deposits of the Priobskoye field by means of the system with toroidal sources and receivers.