bluuebunny/crossref_metadata_2025 huggingface dataset:
Repeatability of Sheet Material Formation Results and Interchangeability of Processing Modes at Multi-Pass Laser Formation
Authors: Kaglyak Oleksii , Romanov Bohdan , Romanova Kateryna , Myrgorod Oksana , Ruban Artem , Shvedun Viktoriia
Published: July 2021

Laser shaping of sheet materials is a flexible process and is carried out without force contact on the material, it allows forming, among other things, brittle, elastic and difficult-to-deformed materials. It is known that the main parameters of laser shaping are the beam power, the size of the focus zone and the speed of beam movement along the surface of the workpiece, however, the range of variation of these parameters is not unlimited, but due to the characteristics of a particular equipment. Therefore, it is necessary to develop an approach to selecting processing modes that can be selected from the range available on the equipment and at the same time obtain a predictable result. There is also a need to investigate a reproducibility of laser shaping results with a lot of pass-through processing. Actually, this study is aimed at solving these issues. In particular, the article formulates a provision on complex formation parameters that allow determining interchangeable modes of laser molding processing and varying parameters in ranges available on equipment. For this, the basic processing mode was chosen, formation was carried out with a fixed number of passes, after which, using complex parameters, alternative modes were determined and formation was carried out under these conditions with the same number of passes. The article also presents the methodology and results of experimental studies of checking the interchangeability of formation modes and the repeatability of formation results during processing along parallel and multi-directional trajectories. It was experimentally found that the deviation of the strain value obtained in alternative modes, compared to the base, and did not exceed 2.46% for a three-pass cycle and 5.8% - for a nine-pass cycle. And the repeatability of the formation results during laser shaping is quite high; the discrepancy in the deformation value did not exceed 5%, and, preferably, was lower.
An Experimental Study on Elastic and Strength Properties of Addictively-Manufactured Plastic Materials
Authors: Potopalska Kseniia , Tyshkovets Olena , Kalinovskyi Andriy , Vasyliev Serhii
Published: July 2021

Additive manufacturing technologies continue to develop extremely fast. Their opportunity of reproducing any given complex geometric form they superior to traditional production technologies. Despite the rapid development and distribution, there are still areas that require special attention for the study of the behavior of materials for 3D printing. This work presents method of defining mechanical property of PLA plastic for 3D printed parts. For this, a full-scale experiment was carried out using specimens created by 3D printing. After carrying out the tensile test, the tensile diagram was determined.
Thiocarbamide-Citrate Electrolytes as an Alternative to Cyanide Electrolytes in Solving the Problems of Environmental Protection and Prevention of Emergency Situations
Authors: Smirnova Olha , Nikonov Andrej , Pylypenko Oleksij , Brovin Aleksandr
Published: July 2021

A comparative analysis of the occupational hazard was done when working with widely known cyanide electrolytes and new thiocarbamide and citrate acid-based electrolytes. For this purpose, we made use of available reference data on maximum permissible substance concentrations, i.e. process solution components. Appropriate computations were done to define the environmental hazard of the electrolytes used for the application of silver, gold and copper coatings and also for the electrochemical silver polishing. Consideration was given to the reactions that proceed in cyanide and thiocarbamide-citrate bathes. The main drawbacks and advantages of given electrolytes have been established. Special attention was paid to the quality of galvanic products. It was proved that the suggested electrolytes are highly competitive with cyanide analogues as for their visual appearance, density and other characteristics of the condition of treated surface. These turned out to be labor saving and energy efficient and have substantially lower harmful effect on the human health and environment.
Influence of Basic Oxides Ratio Li2O/Al2O3, SiO2/Al2O3 and H2O/Al2O3 on Physical, Rheological and Colloidal-Chemical Properties of Lithium Containing Alumosilicate Suspensions in the System xLi2O-Al2O3-nSiO2-mH2O
Authors: Guzii Sergii G. , Kurska Tetiana , Andronov Vladimir , Adamenko Mykola
Published: July 2021

The influence of the main structure-forming oxides Li2O/Al2O3, SiO2/Al2O3 and H2O/Al2O3 on the physical, rheological and colloidal-chemical properties of lithium-containing alumosilicate suspensions xLi2O-Al2O3-nSiO2-mH2O in the system are presented for the first time. As a result of optimization, the optimal area of influence of variable factors was determined for the ratio of oxides Li2O/Al2O3 from 0.82 to 1.05 mol, SiO2/Al2O3 from 3.4 to 4.5 mol and H2O/Al2O3 from 19 to 21.5 mol, providing normative levels of properties of lithium-containing alumosilicate suspensions, namely: density from 1.4 to 1.521 g/cm3, process viscosity from 15 to 47 sec, pH from 11.15 to 11.34, surface tension from 51.4 to 60.4 mN/m, cosine of the substrate contact angle from 0, 57 to 0.91, work of adhesion forces from 97 to 116 mN/m, work of cohesion forces from 103 to 121 mN/m, work of wetting forces from 27 to 52 mN/m, wetting coefficient from 0.78 to 0.96, spreading coefficient from –5 to –20 mN/m. The data obtained will form the basis for the creation of protective materials of new generation that, in the event of emergencies, can provide both the protection of people and technological equipment, buildings and constructions.
Metal Hydride Technologies for Separation of Hydrogen Isotopes
Authors: Umerenkova Kseniya , Borisenko Vitalii , Svetlichna Svitlana , Goroneskul Marianna
Published: July 2021

The paper considers the issue of theoretical prediction of characteristics at which separation of hydrogen isotopes occurs in the “gas-metal” system. Mathematical modeling of sorption is based on the use of the lattice gas model often used for metal hydrides. In contrast to the Leicher ideal solution model, it is taken into account that the dissolution of hydrogen in the metal increases the volume of the crystal lattice. This leads to additional contributions to potential energy. The model also takes into account the interaction between the atoms of the incorporated (absorbed) hydrogen isotopes. These phenomena are described by the methods of thermodynamic perturbation theory. The different composition of the gas (protium and deuterium) in contact with the metal leads to the fact that sorption, accompanied by the formation of hydride, proceeds for the same temperature at different equilibrium pressures. This phenomenon characterizes the isotope effect. The temperature dependences of the pressure on the "plateau" for palladium hydride and deuteride are obtained. The differences in these pressures can be used for the practical use of metal hydrides in the separation of hydrogen isotopes.
Influence of ANO3 and ANO3·nH2O Nitrates on the Deformation Properties of Aluminosilicate Adhesives for Wood Products and Structures
Authors: Guzii Sergii G. , Romaniuk Volodymyr , Lapovska Svitlana Davydivna , Semkiv Oleg , Bazhelka Ihar
Published: July 2021

As a result of the research, the deformation properties of aluminosilicate adhesives modified with nitrate salts and intended for gluing wooden products and structures made of pine, beech and oak wood at different stages of their hardening were determined. Considering that pine is the most common wood in the manufacture of products and structures, then in order to reduce the numerical values of the elastic modulus in glued materials, it is advisable to add ammonium, lithium and sodium nitrates in an amount of 0.5%, potassium nitrate in an amount of 1% into the composition of an aluminosilicate adhesive. which will ensure the approximation of the elastic modulus values to the values of the unmodified aluminosilicate adhesive and will significantly affect the water resistance of the glue joint and the depth of penetration of the adhesive into the wood structure. For gluing beech wood products to reduce the elasticity modulus, it is advisable to introduce 0.5% ammonium and potassium nitrates and 1% lithium and sodium nitrates, which will reduce the numerical values of the elastic modulus in glued materials by 1.18 and 1.53 times compared with the values of the elastic modulus of the unmodified aluminosilicate adhesive. For gluing oak wood products to reduce the elasticity modulus, it is advisable to introduce 0.5% potassium nitrate and 1.5% sodium nitrate, which will reduce the numerical values of the elastic modulus in glued materials by 1.4 and 2.83 times compared to the values modulus of elasticity of unmodified aluminosilicate adhesive.
Research of Operational Properties of Household Fabrics for Production of Protective Masks
Authors: Cheberiachko Serhii , Knysh Ivan , Pustovoi Dmytro , Sharovatova Olena
Published: July 2021

Experimental studies have been conducted to determine the operational properties of fabrics used for the manufacture of protective masks. For the experimental study, 22 different fabrics were used, which are available in everyday life. Determination of the operational properties was carried out according to three indicators: the penetration coefficient of the test aerosol, paraffin oil (filtering property), breathing resistance (ergonomic property), resistance to dusting (protective action period) in accordance with the requirements of DSTU EN 149-2017 standard. According to the results of the experimental study to determine the operational properties of fabrics: breathing resistance, penetration coefficient and resistance to dust, it was found that out of the twenty-two samples tested, only eight can be used for the manufacture of protective masks, since their characteristics are able to provide a sufficient level of protection from minimal physiological impact on human (wool, two-thread cloth, velor, tricotin, jersey, frieze and satin). Theoretical calculation of the operational properties of protective masks, which can be made of these fabrics, based on experimental data allowed to make their compliance with the first class of protection according to the requirements of DSTU EN 149-2017. The scientific novelty is to clarify the relationship between the operational properties of fabrics and the operational properties of protective masks.
Ecological Aspects of Clay Sorption Materials Usage in Leather and Fur Production Technologies
Authors: Malovanyy Myroslav , Blazhko Oleg , Sakalova Halyna , Vasylinych Tamara
Published: July 2021

The work is devoted to solving the current problem of increasing the level of environmental safety of treatment industrial wastewater of leather production from chromium ions (III) through the use of natural and modified bentonite. The studies of natural and modified bentonite use in the adsorption of Cr3 + ions were conducted. The influence of the process duration on the sorption efficiency of chromium ions was studied. Studies were conducted to use spent bentonite in tanning and filling processes. The efficiency of modification of montmorillonite has been proved and the expediency of using mineral dispersion for qualitative formation of the structure and properties of the leather during tanning has been established.
Investigation of the Properties of Powder Materials Using Computer Modeling
Authors: Pasternak Viktoriya , Samchuk Lyudmila , Huliieva Nataliia , Andrushchak Igor , Ruban Artem
Published: July 2021

Granulometric characteristics of structurally inhomogeneous materials based on full-scale mounds of a powder mixture of different fractional composition are established. Regularities of backfilling of powder particles of different shapes and sizes are revealed, and changes in the polydispersity of powder particles within each fraction are justified. It is proved that with a decrease in the average particle size of structurally inhomogeneous AlCu2 materials in a single fraction, the size spread relative to this value of other particles increases. The results of calculating the porosity of backfills with particles of various shapes (round, triangular, and square) depending on the cross-sectional area of the lobules are presented. A three-dimensional diagram is constructed that shows the relationships between the fractional composition of powder particles, their average diameter, and the degree of inhomogeneity of homogeneous bronze AlCu2.
Influence of Temperature Fields on the Quality of Dried Wood Products
Authors: Pinchevska Olena , Spirochkin Andriy , Zavialov Denys , Oliynyk Rostislav
Published: July 2021

The reasons of white spots appearance in the middle of oak timber are determined. These white spots reduce the cost of the lamina made of oak timbers - the front covering of floorboards. It is proposed to intensify the drying process by using oscillating drying schedules to avoid this defect. A method for calculating the duration of such drying is proposed. This method includes the peculiarities of heating and cooling periods kinetics of oak timbers with 25 mm and 30 mm thickness. The inexpediency of using the oscillation of the drying agent parameters in the range of wood moisture content below 20% has been established. An adequate model for calculating wood temperature and air humidity during wood heating and cooling periods has been developed using heat and mass transfer criteria and experimentally determined oak wood moisture conductivity coefficient. Based on the results of theoretical and experimental studies oscillating drying schedules of different thickness oak timbers are offered. Tests of the proposed schedules in industrial conditions showed no discoloration of the central layers of European oak (Quercus robur) timbers. The drying process duration was reduced by 1.5–2.4 times and energy consumption were reduced by 1.53 times.
Investigation of the Limit of Fire Resistance of a Steel Beam at Loss of Integrity of a Fire-Resistant Lining
Authors: Nuianzin Oleksandr , Pozdieiev Serhii , Borsuk Olena , Nekora Olha
Published: July 2021

In this article, to solve the main problems, we determined the temperature regime of heating the steel beam, which took into account the fact of loss of integrity of the fire-retardant lining due to the thermal effects of fire. When calculating the temperature, the time of exposure to the standard temperature of the fire and the value of the heating temperature of the steel beam with mineral wool lining at which the latter loses its integrity was determined. Taking into account the geometrical parameters of the cross section of the studied I-beam, according to the finite-element scheme, the steel beam was divided into four elements of SHELL type with five points of integration in thickness in the Belichko-Tsai formulation. After the calculation, the corresponding results were obtained in the form of graphs of changes in the maximum deflection of the beam and the rate of increase of the maximum deflection depending on the time of exposure to the standard temperature of the fire. The critical values of the occurrence of the limit of fire resistance according to the graph of maximum deflection and the graph of the rate of increase of deflection were determined. The difference between the indicators shows that the time of the limit state of loss of bearing capacity is 70 min less, if not taking into account the loss of fire-retardant capacity of mineral wool fire-protection due to loss of integrity.
Experimental Study of the Insulating Properties of a Lightweight Material Based on Fast-Hardening Highly Resistant Foams in Relation to Vapors of Toxic Organic Fluids
Authors: Pietukhov Ruslan , Kireev Oleksandr , Tregubov Dmytro , Hovalenkov Serhii
Published: July 2021

To isolate the surface of toxic liquids, it is proposed to use fast-hardening highly resistant foams. To obtain fast-hardening, highly resistant foams, the process of gel and foaming is combined. For this, solutions of sodium polysilicate and gelation catalyst are mixed. To increase the stability of the foams, it is proposed to add water-soluble polymers to the gel-forming composition. It is shown that a fast-hardening foam of the composition Na2O·2.5SiO2 (9%)+NaHCO3 (9%)+6% foaming agent +0.5% carboxymethyl cellulose with thickness reduces the mass rate of benzene evaporation by more than 5 times. It retains its insulating properties for more than 5 days. It is concluded that it is advisable to use fast-hardening highly resistant foams for the elimination of emergencies with the spill of toxic liquids.
Applying Ultrasound Detection Devices to Examine Pгореrties of Concrete Structures
Authors: Kolokhov Viktor
Published: July 2021

The article considers the problems of diagnostics of reinforced concrete structures and creation the generalized calibration dependence for the use of ultrasonic devices. The results of the study of the influence of some factors on the results of measuring the dissemination time of ultrasonic vibrations are presented. The study was conducted using devices "Pulsar 1.1" and "Novotest IPSM-U" in compliance with regulatory requirements. Statistical processing of the obtained results (with visualization) was performed using the software package EXEL. Processing of the obtained data confirmed the multifactorial dependence of ultrasonic measurements on the concrete surface. The lack of clearly defined conditions for measurements reduces the reliability of the results. The use of ultrasonic measurements to obtain absolute values of the properties of concrete is not adequate. It is proposed to make changes to the regulations regarding the limits of application of ultrasonic measurements.
Numerical Evaluation of Safety Wall Bending Strength during Hydrogen Explosion
Authors: Skob Yurii , Ugryumov Mykhaylo , Dreval Yuriy , Artemiev Sergey
Published: July 2021

The main aims of this study are to assess numerically the stress state of a solid wall which is installed at the hydrogen fueling station in order to protect personnel from the consequences of the accidental hydrogen explosion, define the bending stress values in the foot of the wall exposed to explosion wave pressure forces and located at different distances from explosion epicenter in order to choose appropriate construction material of the wall and assess the minimum thickness of the wall satisfying bending strength condition. A three-dimensional mathematical model of hydrogen-air mixture explosion is used to define the distribution of the maximum overpressure on the wall surface. To assess the bending stress state at the foot of the wall, the design scheme of a cantilever beam is considered. It is assumed that the maximum overpressure force field influences the wall at the same time to assess the worst possible scenario. Actually, the computer-based methodology of how to resolve a coupled problem of explosion gas dynamics and defense wall strength is suggested. This technique allows evaluating of the construction parameters of the wall, which protects the personnel against consequences of the explosion wave exposure, without the destruction of the wall.
Investigation of Gas Formation Processes in Cotton Fabrics Impregnated with Binary Compositions of Ethyl Silicate - Flame Retardant System
Authors: Skorodumova Olga , Tarakhno Olena , Chebotaryova Olena , Saveliev Dmitriy , Emen Fatih Mehmet
Published: July 2021

The use of complex fire-retardant coatings based on ethyl silicate gel - diammonium hydrogen phosphate reduces the process of smoke formation during thermal exposure to treated tissue samples, which is promising for improving the fire safety of textile materials. The compositions are easy to obtain, they do not require specific processing conditions, do not contain toxic substances. This allows us to offer developed compositions for fire protection of textile materials used in facilities with a large number of people.
Investigation of the Processes of Formation of a Fire Retardant Coating
Authors: Chernukha Anton , Chernukha Andrii , Ostapov Konstantin , Kurska Tetiana
Published: July 2021

The processes of phase formation in a fire retardant composition based on liquid glass and potassium carbonate have been investigated. The mechanism of the process has been studied. It was found that the use of potassium carbonate provides controlled gas evolution during heat treatment of the composition, as a result of which the integrity of the fire retardant coating is preserved.
Thermodynamic Study of Fire-Protective Material
Authors: Chernukha Anton , Chernukha Andrii , Kovalov Pavlo , Savchenko Alexander
Published: July 2021

The paper considers the material for the protective coating of building structures made of wood. The possibility of chemical processes occurring in the material leading to its expansion has been studied. The coefficient of expansion of the material when heated is practically established. It has been established that the material can swell, both under the influence of flame and when the temperature rises at a low speed. Swelling coefficient at the same time it reaches 8. The temperature range of swelling is 150–250 С, which is confirmed by thermodynamic calculations and experimentally. The temperature at which the material begins to swell is lower than the temperature of thermal destruction of wood.
Modeling of Non-Stationary Heating of Steel Plates with Fire-Protective Coatings in Ansys under the Conditions of Hydrocarbon Fire Temperature Mode
Authors: Kovalov Andrii , Otrosh Yurii , Chernenko Oleksandr , Zhuravskij Maxim , Anszczak Marcin
Published: July 2021

The results of the experimental determination of temperature from a non-heating surface of steel plates with a fire-protective coating under conditions of fire exposure under the hydrocarbon fire temperature regime are presented. A calculated finite element model of the system “steel plate-flame retardant” was constructed to simulate the non-stationary heating of such a system in the ANSYS R17.1 software complex. The reliability of the numerical simulation results is estimated by real test, the adequacy of the developed model to the real processes occurring when heating the steel plates with fire-protective coating under the conditions of hydrocarbon fire temperature mode is made.
Determination of the Fire-Retardant Efficiency of Magnesite Thermal Insulating Materials to Protect Metal Structures from Fire
Authors: Guzii Sergii G. , Otrosh Yurii , Guzii Olena , Kovalov Andrii , Sotiriadis Konstantinos
Published: July 2021

This paper presents the results of fire test of an I-beam protected by a combined magnesite plate-magnesite mixture heat-insulating material. It was shown that a composite with an average thickness of 37 mm maintained an average temperature of 380 °C on the metal surface after 150 minutes of fire exposure, not exceeding the critical value of 500 °C. From 60 to 100 minutes of fire testing (furnace temperature of 980-1025 °C), the temperature of the metal did not exceed 100 °C. This was achieved both due to the high thermal insulation properties of the magnesite mixture, and due to gas and vapor release from the hydration products of magnesia cement. The developed fire-retardant material provides the first group of fire-retardant efficiency (150 minutes) and, after the fire test, is characterized by density of 352.4 kg/m3 and compressive strength of 0.85 MPa, which is three times lower than the original.
Research of Mechanism of Fire Protection with Wood Lacquer
Authors: Tsapko Yuriy , Lomaha Vasyl , Tsapko Oleksii , Bondarenko Olga P.
Published: July 2021

The results of researches of wood burning parameters and influence of fire-retardant substances on them are given. Studies have shown that the process of heat insulation of a wooden structure is the formation of soot-like products on the surface of natural combustible material. Under the action of the burner flame on the protected sample treated with impregnating solutions based on a mixture of ammonium phosphate with antiseptic, the temperature of gaseous combustion products was 230 oC, and weight loss did not exceed 9%, while wood treated with a composition of urea and phosphoric acids and starch showed temperature of 160 oС with a weight loss of 3.6%. It is established that fire protection by coatings provides a low rate of burnout of wood samples and with increasing temperature exposure and translates into a non-flammable material that does not spread the flame on the surface.
Alternative Strengthening of Jewelry Tools Using Chemical-Thermal and Local Surface Treatments
Authors: Volkov Oleg , Knyazev Sergey , Vasilchenko Alexey , Doronin Evgen
Published: July 2021

The study is aimed at surface strengthening of jewelry tools. Samples in the form of a tool with a flat and curved surface profile are considered. Macrophotographs of jewelry korneisen at different stages of wear, as well as after restoration and strengthening are given. The results of the influence of chemical-thermal and thermo-friction treatments on the structure and properties of U7 and U8A steels used for jewelry tools are presented. The methodology of experimental researches is given. The equipment used for each of the hardening methods investigated in this work is considered. Auxiliary media and features of sample preparation for the experiment are also described. Photos of samples and some equipment at different stages of the study are given. Data on the distribution of microhardness, photographs of microstructures in cross section of samples after different types of hardening are presented. A comparison of the strengthening efficiency of the samples after the use of different processing methods is performed.
Electrochemical Formation of Oxide Films on the Titanium Alloy of Ti6Al4V in Ethylene Glycol-Water Electrolytes to Produce Bioinert Coatings and Increase the Corrosion Resistance of Medical Implants
Authors: Smirnova Olha , Nikonov Andrej , Mukhina Yulia , Pylypenko Oleksij
Published: July 2021

The research data on the specific features of the formation of oxide films on the Ti6Al4V alloy in the ethylene glycol-water electrolytes have been given. The kinetic dependences obtained for the alloy allowed us to establish that the specific features of the formation of oxide films during the electrochemical oxidation of the alloy surface depend on the solution composition and the current density. For the water-to-alcohol ratio of 50:50 the kinetic dependences show the sections that correspond to the formation of the barrier oxide layer and also to the formation of the pores due to the desorption of fluoride ions and the growth of the porous portion of oxide. As the water-to- alcohol ratio is decreased the indicated peculiarities of kinetic dependences are met not so often and do not obey any regularity. The obtained data are explained by the fact that an increase in the portion of the organic component of the solution results in a decreased etching capacity of the electrolyte due to the controlled activity of fluoride ions. The anode current density value has a similar effect on the variation of kinetic dependences. Its effect is explained by that an increase in the alloy oxidation rate results in the fast formation of the surface oxide and the specific features of kinetic curves are concealed. The linear relationship between the formation time of oxide of a minimum thickness for given conditions and the current density is unavailable and it is conditioned by the chemical interaction of the oxide film with electrolyte components. The obtained research data can be used for the formation of the individual bioinert and bioactive coatings for the implants of a medical purpose or for the formation of the matrix used for the production of composite coatings.
Research of the Microstructure of the Deposited Layer during Electric Arc Surfacing with Control Impacts
Authors: Ivanov Vitaliy , Lavrova Elena V. , Kibish Vladyslav , Mamontov Ihor
Published: July 2021

Electric arc surfacing is widely used for the application of protective and restorative coatings on units and parts of metallurgical production equipment in order to increase their durability in harsh operating conditions and in an aggressive environment. Increasing the efficiency of melting the electrode material is an important task, since it allows one to reduce the required volume of deposited metal and the cost of surfacing. In addition, when surfacing by traditional technology of parts with a complex shape of the working surface, it was found that the deposited layer can contain such defects as single gas and line pores, as well as slag inclusions. The work is devoted to the study of improving the surfacing technology by controlling heat input into the base metal using controlled mechanical actions.
Effects of the lncRNA ENST00000623984 on colon cancer and the biological characteristics of colon cancer cells
Authors: Liu Zhi-bao , Zhang Jing-hua , Gao Jing-hua , Shi Jian
Published: July 2021

The aim of this study was to explore the effects of the lncRNA ENST00000623984 on colorectal cancer. In this study, the expression levels of ENST000000623984 were first examined in tumor tissue and adjacent normal tissue from 40 patients with colorectal cancer and LoVo cells using quantitative real-time PCR. By siRNA transfection, ENST00000623984 expression was knocked down. Using flow cytometry, cell cycle progression and cell viability were examined in basal and knockdown LoVo cells. The CCK-8 assay was used to assess the cell proliferation rate, and the Transwell assay was used to determine the migration and invasion abilities. The ENST000000623984 expression level was increased in colorectal cancer. Knockdown of ENST000000623984 reduced cell viability, proliferation rate, cell migration and invasion. These results suggested that lncRNA ENST000000623984 may be involved in colorectal cancer development.
Exploiting high frequency monitoring and satellite imagery for assessing chlorophyll-a dynamics in a shallow eutrophic lake
Authors: Pinardi Monica , Free Gary , Lotto Beatrice , Ghirardi Nicola , Bartoli Marco , Bresciani Mariano
Published: July 2021

Freshwater ecosystems are challenged by cultural eutrophication across the globe, and it is a priority for water managers to implement water quality monitoring at different spatio-temporal scales to control and mitigate the eutrophication process. Phytoplankton abundance is a key indicator of the trophic and water quality status of lakes. Phytoplankton dynamics are characterized by high spatio-temporal variation, driven by physical, chemical and biological factors, that challenge the capacity of routine monitoring with conventional sampling techniques (i.e., boat based sampling) to characterise these complex relationships. In this study, high frequency in situ measurements and multispectral satellite data were used in a synergistic way to explore temporal (diurnal and seasonal) dynamics and spatial distribution of Chlorophyll-a (Chl-a) concentration, a proxy of phytoplankton abundance, together with physico-chemical water parameters in a shallow fluvial-lake system (Mantua Lakes). A good agreement was found between Chl-a retrieved by remote sensing data and Chl-a fluorescence data recorded by multi-parameters probes (R2 = 0.94). The Chl-a maps allowed a seasonal classification of the Mantua Lakes system as eutrophic or hypertrophic. Along the Mantua lakes system an increasing gradient in Chl-a concentration was recorded following the transition from a fluvial to lacustrine system. There was significant seasonal heterogeneity among the sub-basins, probably due to different hydrodynamics, influenced also by macrophyte stands. High-frequency data revealed the importance of rainfall events in the timing and growth dynamics of phytoplankton, particularly for spring and late summer blooms. Combining temporal and spatial data at high resolution improves the understanding of complex fluvial-lake systems. This technique can allow managers to target blooms in near-real time as they move through a system and guide them to localized hot spots enabling timely management action in ecosystems of high conservation and recreational value.
Is the Profession of Dentistry Losing its Yesteryear'S Glory? an Exploratory Study from Dental Students' Perspective
Authors: Bommireddy Vikram Simha , Chandu Viswa Chaitanya , Kommineni Harish Chowdary , Vijaykumar Anu , Ravoori Srinivas , Neeli Gayathri Spandana
Published: July 2021

Introduction:

The regard for dentistry as a profession has been declining over the recent years in light of the increasing number of dental students graduating per year with negligible improvement in the utilization of oral health care services. In this context, it is important to document the perceptions and apprehensions of the current dental students as these feelings would have an influence on the roles they assume as dentists in future.

Aim:

With this background, this study attempts to document the willingness of dental students from three South Indian states to re-choose dentistry given an opportunity.

Materials and Methods:

This cross-sectional survey was conducted among house surgeons from 12 dental institutions, 4 each from the southern Indian states of Andhra Pradesh, Telangana, and Tamilnadu. The semi-structured questionnaire used in this study consisted of five primary questions along with details on the participants' gender, type of admission. It aimed at documenting the willingness to re-choose dentistry given an opportunity, and the reasons for their willingness or otherwise. A total of 822 students constituted the final sample. SPSS version 20 software was used to analyse the data.

Results:

Majority of the study participants were from Tamil Nadu, not reported dentistry as their primary career choice, and demonstrated reluctance in re-choosing dentistry given an opportunity. A significantly higher percentage of dental students from Tamil Nadu reported dentistry as their first professional choice. This observation persisted in the response of students for the question on their willingness to re-choose dentistry.

Conclusion:

The study results demonstrate the declining interest and regard for dentistry among the current dental students with nominal variations between students from the three South Indian states.
Analysis of the Association Between Polymorphisms in Vitamin D Receptor Gene and Dental Caries
Authors: Protyusha GB , Sundharam B Sivapatha
Published: July 2021

Background:

The influence of environmental factors on dental caries is a well-established fact; however, little is known about the impact of genetics on the caries process.

Aims:

This study was aimed to analyse the association between the vitamin D receptor (VDR) gene polymorphism and dental caries. It also compared the risk of dental caries between individuals with homozygous (tt and TT) genotype and heterozygous (Tt) genotype. Further, this study also aimed to compare VDR gene polymorphism by gender.

Methodology:

A total of 196 subjects were selected based on their decayed, missing, filled teeth (DMFT) index according to the WHO guidelines (1997), and were divided into two groups based on caries experience. The case group was further classified into low and high caries groups. The saliva samples were collected, DNA was extracted, and VDR Taq1 (T/C) gene polymorphism was analysed by polymerase chain reaction–based restriction fragment length polymorphism (PCR-RFLP) and visualized under 2% agarose gel.

Results:

There was no significant difference in the VDR Taq1 polymorphism and dental caries between the case and control group. However, further stratification showed a statistically significant difference based on caries experience in the study group. The heterozygous mutant genotype (Tt) was associated with a higher caries experience (62.1%) (P = 0.008) with the frequency of ‘t’ allele being 77% as compared to ‘T’ allele (63.6%) in the high caries group.

Conclusion:

VDR Taq1 gene polymorphism does not seem to have a role in the incidence of dental caries in the studied population; however, it may have a role in the severity of the caries process.
Gstm1 Null Polymorphism and Palmar Dermatoglypics in Oral Leukoplakia
Authors: Yogesh Lakshanika , Aswath Nalini
Published: July 2021

Background:

An individual's risk towards development of cancer depends not only on environmental factors or extrinsic exposure to carcinogens but also on individual's genetic susceptibility.

Aim:

To determine two genetically established parameters such as prevalence of GSTM1 null polymorphism and analysis of Palmar dermatoglypics (PD) in patients with Oral Leukoplakia (OL) and Controls.

Materials and Methods:

Group I (cases) 30 patients with established histopathological diagnosis of OL and Group II (controls) 30 patients without any habits of tobacco, alcohol usage and without OL were selected. After informed consent, the palm prints were recorded using a Canon PIXMA MP250 scanner and 2 ml of blood was collected and transported under cold cycle and taken for evaluation of GSTM1 null polymorphism using Multiplex PCR.

Results:

There exists a highly significant difference in GSTM1 null polymorphism (p-0.002), Finger ridge patterns (arches- p-0.027, loops p-0.001, whorls p-0.001), hypothenar pattern (p-0.015), ATD angle (p-0.001), AB count (p-0.007) between cases and controls. Similarly, when analysing the GSTM1 null polymorphism with PD among cases, there exists a significant association between loops (p-0.001), AB count (p-0.058) and hypothenar pattern (p-0.076), respectively 43% of OL cases had alteration in both which implies that those patients are at a higher risk of developing cancer.

Conclusion:

Not all patients who smoke or chew tobacco develop cancer. This could probably be due to the individual's genetic susceptibility. Environment gene interactions, in the form of GSTM1 polymorphism, and carcinogenesis, share links that can help in the prediction of risk for oral cancer development, and use of such markers can aid in prediction of oral cancer susceptibility in exposed individuals. Palm prints once formed do not change throughout life and are not influenced by environment. It can also serve as genetic markers to predict the risk of occurrence of oral cancer.
Assessment of Salivary Thiocyanate Levels and Ph in the Saliva of Smokers and Nonsmokers with Chronic Periodontitis – A Comparative Study
Authors: Kumar C Naresh , Rao Subramaniam M , Jethlia Ankur , Linganna Chandra Shekhar , Bhargava Manish , Palve Devendra H
Published: July 2021

Background:

It has been speculated that the pathogenesis of diseases prompted by cigarette smoking includes oxidative damage by free radicals. Though, definitive evidence that smoking may cause the oxidative modification of target molecules in vivo is lacking. Therefore, the purpose of this study was to estimate and compare the levels of salivary Thiocyanate (SCN) and power of hydrogen (pH) in the saliva of smokers and nonsmokers with chronic periodontitis (ChP).

Materials and Methods:

A study population consisted of 60 male systemically healthy subjects in the age group of 20-65 years that was further divided into three groups: Group 1: 20 Healthy nonsmokers, who never smoked. Group 2: 20 nonsmokers with chronic periodontitis. Group 3: 20 smokers with chronic periodontitis. Unstimulated saliva was collected for at least 5 mins and clinical parameters; salivary pH and SCN thiocyanate levels were assessed using the spectrophotometric method. Statistical analysis was performed using SPSS Inc 21.0, Chicago, II, United States of America.

Results:

Data showed that the mean salivary SCN level, periodontal parameters were higher in smokers with chronic periodontitis as compared to nonsmokers with chronic periodontitis and healthy subjects (P < 0.05.) Post Hoc tests multiple comparisons Tukey Honest Significant Difference (HSD) among three groups were statistically significant (P < 0.05).

Conclusion:

Salivary thiocyanate levels remain increased by smoking in addition to the impact of periodontitis, and these results also indicated a significant change in the pH depending on the severity of the periodontal condition in smokers. Thus, the measurement of salivary thiocyanate may prove to be useful in the early detection of periodontal disease. The salivary pH shows significant changes and, consequently, relevant to the severity of the periodontal disease. Salivary pH may thus be used as a quick chairside diagnostic biomarker.
Comparative Evaluation of Periodontal Inflammatory Conditions Among Gutka-Chewers with and without Prediabetes
Authors: Bhardwaj Puneet , Chowdhary Zoya , Sharma Vandana , Ladani Ravi , Modi Sonamben Kishorchandra , Bhardwaj Sudhanshu , Hundal Kasper D.
Published: July 2021

Background:

The metabolic syndrome has become one of the major public-health challenges worldwide which include diabetes, prediabetes (raised blood glucose level), abdominal obesity, high cholesterol level, and high blood pressure. Periodontitis is described as a multi-factorial irreversible and cumulative condition and, is also the sixth complication of diabetes. Areca nut chewing has already been linked with the development of various cancers, and more recently with metabolic syndrome. Therefore, the purpose of the study is to investigate the association of periodontal inflammatory conditions among gutka chewing with and without prediabetes patients.

Materials and Methods:

There are about 50 pre-diabetic and 50 healthy patients, both males and females with the age range of 18 years to 45 years, were included in the study. They were then divided into 4 groups based upon gutka chewers and non-chewers i.e., pre-diabetic gutka chewers (PDC), pre-diabetic non-chewers (PDNC), healthy gutka chewers (HC), and healthy non-chewers (HNC). A complete demographic data was obtained along with clinical and radiographic parameters i.e. plaque index (PI), sulcus bleeding index (SBI), probing depth (PD), marginal bone loss (MBL) were recorded. A statistical analysis was performed and Bonferroni adjustment post hoc test was performed for multiple comparisons.

Results:

The overall results suggested that the clinical periodontal parameters i.e., PD, PI, SBI and radiologic parameters i.e., MBL are significantly higher in prediabetes chewers compared with healthy chewers and healthy non chewers.

Conclusion:

The periodontal inflammatory conditions are worse in gutka chewers compared to non-chewers in healthy and pre-diabetic patients, concluding that the severity of periodontal inflammation is governed by hyperglycemia when compared to habitual gutka usage.
A Very Rare Case of Bilateral Capillary Hemangioma of Lower Lip And Face
Authors: Ujala Ujjwal A. , Diwakar N. R.
Published: July 2021

Hemangioma is a relatively common benign proliferation of blood vessel that primarily develops during childhood. It is a most common benign tumor of vascular origin is the region of head and neck. The common sites are lips, tongue, buccal mucosa, and palate in oral cavity. Due to aesthetic concern and appearance problems of the hemangioma of lower lip and face it requires appropriate management. This is a case report of a rare hemangioma of lower lip and face bilaterally with involvement of mandible, floor of mouth, oropharynx, anterior 2/3rd of tongue parotid/submandibular glands in a 46-years-old female along the course of facial artery bilaterally with arterial feeders from the facial artery bilaterally, and draining into the jugular veins. This type of case is being reported first time in English literature.
Analysis of Erythrocytes in Oral Submucous Fibrosis – A Morphometric Study
Authors: Wadhwan Vijay , Venkatesh Arvind , Sharma Preeti , Malik Sangeeta , Saxena Chitrapriya
Published: July 2021

Background:

Oral submucous fibrosis (OSMF) is a chronic progressive scarring oral disease caused due to areca quid chewing. The constituents of areca nut can enter into the circulation by swallowing the liquid mixture of areca quid which evokes oxidative stress on RBC membrane integrity.

Aims:

To study the morphometric characteristics of erythrocytes under light microscopy and to assess the role of areca quid constituents on the morphology of circulating erythrocytes.

Materials and Methods:

Peripheral blood smears prepared from blood samples of 50 patients selected according to Lai's classification. Group I: Normal individuals (10 cases); Group II: Mouth opening > 35 mm (10 cases); Group III: Mouth opening 30-35 mm (10 cases); Group IV: Mouth opening 20-30 mm (10 cases) and Group V: Mouth opening < 20 mm (10 cases). The slides were stained with Leishman's stain and assessed by light microscopy. A total of 100 randomly selected RBCs from 5 different fields in each smear were selected and the RBC circumference was measured and tabulated.

Statistical analysis and Results:

Data was analyzed using GraphPad Prism 5.03 software. Tukey's multiple comparison test showed statistically significant difference (P < 0.05) between groups I and IV; I and V; II and IV; II and V; III and IV; III and V.

Conclusion:

These results suggest the possibility of cytotoxic effect of areca quid constituents on circulating erythrocytes in advanced cases of OSMF, which might result in microcytic anaemia.
Florid Cemento-Osseous Dysplasia
Authors: Thakur Arush , Gaikwad Shuddhodhan , Tupkari Jagdish Vishnu , Ramaswami Easwaran
Published: July 2021

Cemento-osseous dysplasia is non-neoplastic, reactive fibro-osseous lesions that affect the tooth-bearing areas of the jaws. Osseous dysplasia is further divided into three subtypes: Periapical osseous dysplasia, focal osseous dysplasia, and florid osseous dysplasia. We hereby, present a case of florid cemento-osseous dysplasia occurring in a 40-year old dentulous Indian woman. The patient presented with lesions involving the mandibular right and left quadrant.
Estimation of Occlusal Vertical Dimension using Cephalometric Angular Reconstruction
Authors: Vinnakota Dileep Nag , Kamatham Rekhalakshmi
Published: July 2021

Aim:

To propose a new technique, based on cephalometrics for determining the vertical dimension of occlusion (VDO).

Methods and Material:

Thirty-five participants in the age range of 20–22 years who met the inclusion criteria were recruited. Lateral cephalograms were obtained and tracing done. Five reference landmarks, Nasion (N), Anterior Nasal Spine (ANS), Porion (P), Gonion (G) and Gnathion (Gn) were marked and joined to form four angles, N-ANS-Gn, N-ANS-G, P-G-Gn and P-G-ANS; distance between ANS and Gn was considered as VDO in cephalogram (VDO-Ceph). The angles N-ANS-Gn and N-ANS-G; P-G-Gn, and P-G-ANS were correlated; two simple linear regression models were developed to predict N-ANS-Gn and P-G-Gn, using N-ANS-G and P-G-ANS, as independent variables. Using the formulae, the predicted angles, N-ANS-Gn and P-G-Gn were drawn and intersection marked as ‘reconstructed point Gn’. The predicted VDO-Ceph values (distance between ANS and reconstructed Gn) were measured and correlated with actual values.

Results:

The angles N-ANS-Gn and P-G-Gn had a statistically significant positive correlation with N-ANS-G (r = 0.77, P < 0.001) and P-G-ANS (r = 0.83, P < 0.001), respectively. Using simple linear regression analysis, the following formulae were obtained: N-ANS-Gn (in degrees) = 1.271 N-ANS-G (in degrees) + 24.83 and P-G-Gn (in degrees) = 0.987 P-G-ANS (in degrees) + 35.93. The predicted and actual VDO-Ceph values showed no statistical significance difference (P = 0.92).

Conclusion:

By tracing four cephalometric landmarks, N, ANS, P, G; and using the angular reconstruction, it is possible to predict the location of Gn. Hence, during prosthetic replacement of lost teeth, this can be employed for the estimation of lost dimensions.