Analysis of the terms of usage of non-removable restorations fixed by different glass ionomer cements

Preservation and restoration of dental health of patients is achieved by early detection and treatment of diseases, finding ways of individual prevention, detection and elimination of risk factors for their development. The amount of materials significantly increased used to restore the integrity of teeth and dentition. Among them are dental materials for permanent fixation of indirect non-removable restorations. The material is used to fill the space between the inner surface of the artificial structure and the support element. This helps to mechanically fix the restoration in place to prevent its displacement during chewing. The correct choice of dental material for permanent fixation is an important decision and will determine the long-term success of permanent restorations. The aim of the study is to analyze the durability using non-removable structures of dentures mounted on different glass ionomer cements.

Peningkatan Kerapatan Kayu Samama Melalui Pre-kompresi Asam Sitrat (Density Improvement of Samama Wood by Pre-compression of Citric Acid)

Samama wood (Anthocephalus macrophyllus (Roxb.) Havil.) is a potential fast-growing species of Sulawesi and Maluku. This study aimed to increase the density of the wood through citric acid pre-compression. The temperature/time pressing formula and the optimal concentration of citric acid for fixation were also determined. Water saturated samples of (5x5x4) cm3 (L = longitudinal x T = tangential x R = radial) were pre-compressed at 100 °C for one hour to reach drying set. Subsquently, the samples were soaked for 4 hours in a citric acid solution of 5% and 10% concentration, drained and wrapped in aluminum foil before re-pressed at 180 °C for 10, 20, 30, 40, 50, and 60 minutes. Fixation was measured by soaking the samples into water for 24 hours at room temperature. The results showed that the moisture contents at fiber saturation point ranged from 33.15-33.94%, with density of 0.46 g cm-3 and oven dry density of 0.37 g cm-3. The L, T, and R shrinkages were 0.18-0.20%, 4.13-4.14%, and 2.53-3.10%, respectively; while the T/R ratio was 1.33-1.63%. Pre-compression can only be done at a compression target of 25% with compression level of 19.57-20.01%. Pre-compression increased the oven dry density of 17.11-20.13% to 0.44-0.45 g cm-3. After thickness recovery, the weight of the oven dried samples increased by 1.79-2.72% at the 5% citric acid concentration and by 12.04-15.25% at the 10% citric acid concentration. Permanent fixation achieved at 180 °C for 50 minutes pressing time with 10% citric acid concentration.

The transcriptional and splicing changes caused by hybridization can be globally recovered by genome doubling during allopolyploidization

Allopolyploidization, which involves hybridization and genome doubling, is a key driving force in higher plant evolution. The transcriptome reprogramming that accompanies allopolyploidization can cause extensive phenotypic variations, and thus confers allopolyploids higher evolutionary potential than their diploid progenitors. Despite many studies, little is known about the interplay between hybridization and genome doubling in transcriptome reprogramming during allopolyploidization. Here, we performed genome-wide analyses of gene expression and splicing changes during allopolyploidization in wheat and brassica lineages. Our results indicated that both hybridization and genome doubling can induce genome-wide transcriptional and splicing changes. Notably, the gene transcriptional and splicing changes caused by hybridization can be largely recovered to parental levels by genome doubling in allopolyploids. Since transcriptome reprogramming is an important contributor to heterosis, our results revealed that only part of the heterosis in hybrids can be fixed in allopolyploids through genome doubling. Therefore, our findings update the current understanding of the permanent fixation of heterosis in hybrids through genome doubling. In addition, our results indicated that a large proportion of the transcriptome reprogramming in interspecific hybrids was not caused by the merging of two parental genomes, providing novel insights into the mechanism of heterosis.

COMPARATIVE EVALUATION OF PHYSICO-MECHANICAL PROPERTIES OF DENTAL CEMENTS FOR PERMANENT FIXATION OF ORTHOPEDIC CONSTRUCTIONS

Fixation of indirect constructions restoration with permanent cement is the final clinical stage of orthopedic treatment. It should be noted that the result of the treatment with the using of unremovable dentures essentially depends on the correct choice of cement for fixation. The comparative analysis conducted to improve the quality of fixing method of unremovable dentures was carried out on the base of the Research laboratory of dental materials and products of JSC «STOMA», Ukraine. We used the following materials: glassionomer cements “KetakCem”, Germany; “Riva”, Australia. The study of physico-mechanical properties of materials was carried out according to the following parameters: determination of the strength of the diametrical stretching (T, MPa), bending strength (σ, MPa), determination of the water absorption index (W, μg / mm³), free linear shrinkage (L,%), solubility index (D,%), and compressive strength (C, MPa). At the determination of the strength the diametrical stretching index (T, MPa) according to the results of laboratory tests "Ketac Cem", "Riva" and the new glass ionomer cement developed by us for permanent fixing of unremovable dentures.We have received that the indices of all selected cements are within 8.8 - 9.9 MPa which are close to international standards ISO 4104. Also we found out that the boundary value at the diametral stretched "Riva", which is (8.9 ± 0.3) MPa, is not greater than Ketac Cem (9.9 ± 0.6) and is reliably non-existent significant differences (p> 0.05). The glass ionomer cement developed by us with an index of 8.8 ± 0.5% (T, MPa) with a certainty (p> 0.05) has no difference between the indicators of «Ketac Cem» and «Riva» materials. Consequently, the strength limit at the diametrical extension of a new glass ionomer cement for permanent fixation has no significant difference compared with its foreign analogues (p> 0,05). The strength of the curtain (σ, MPa) of the materials under investigation for fixing unremovable dentures varies within (55.9 ± 70.2). It was found out that the durability of a new glass ionomer dental cement is (58.3 ± 0.4%). It is significantly lower (p <0,001) than the ‘Ketac Cem’ material - 70,2 ± 0,7%, while the "Riva" (55,9 ± 0,8%) has the least value. We indicate that the strength of the material @Riva "is significantly lower (p <0.001). In determining the rate water absorption, we obtained the following results: the glass ionomer cement developed by us has the limits of water absorption which is 42.7 ± 0.4 μg / mm3 compared with the analogues Ketac Cem and Riva - 36.3 ± 0.6 and 39 , 7 ± 0.3 μg / mm 3, respectively. The data of statistical processing showed that the water absorption of glass ionomeric cements is significantly lower (p <0,001). Free linear shrinkage of new glass ionomer cement has limits of 0,44 ± 0,03%, which exceeds the value of "Ketac Cem" (0,33 ± 0,02) by 0,11±0,01%, and is significant (p <0, 05) is less in comparison with "Riva", the index of which is 0,66±0,09%. The solubility index of the cement we developed is 1.30 ± 0.16%, which is 0.07 ± 0.03% higher than Ketac Cem - 1.23 ± 0.17%, but not significantly different from the material "Riva ", which index is 1.32±0.14%, which corresponds to ISO, but these data do not have statistically significant differences (p> 0.05). The results of the compression strength index are characterized not by a significant difference between them: the cement developed is 76.2 ± 0.4% MPa, which is significantly (p <0.001) 2.4 ± 0.1% less than Ketac Cem - 78.6 ± 0,5%, but does not have a significant difference (p> 0,05) between the developed material and the «Riva» index which is 76,0 ± 0,8%, respectively.

Covalent fixation of boron in wood through transesterification with vinyl ester of carboxyphenylboronic acid

Vinyl ester of 4-carboxyphenylboronic acid has been synthesized and tested as reactive reagent for permanent fixation of boron in wood based on an improved approach described previously. The essence of the method is a covalent incorporation of the boron compound via transesterification between wood hydroxyl groups and vinyl ester containing boron. The synthesis of this vinyl ester was accomplished by exchange reaction of vinyl acetate with 4-carboxyphenylboronic acid. The obtained vinyl ester of carboxyphenylboronic acid was characterized by FTIR and 1H-, and 13C-NMR spectroscopy. The covalent fixation of boron to wood’s hydroxyl groups was achieved through potassium carbonate (K2CO3) catalyzed transesterification of the vinyl ester containing boron. The transesterification was confirmed by weight percentage gain (WPG) calculation, curcumin staining, FTIR, and 13C CP-MAS NMR spectroscopy. The efficiency of the reaction improved with increasing temperature and reaction time.

Sequestration of supercritical CO2 by mercury oxide

HgCO3·2HgO (mercury oxide carbonate), along with partly unreacted reactants, was obtained by exploring the behaviour of the Hg2Cl2/HgO binary system in supercritical CO2 (scCO2) at 200°C, 22000 kPa in the presence and absence of water, using a self-made laboratory-scale system. The reaction of pure HgO with scCO2 aimed at the synthesis of HgCO3 (mercury carbonate), also yielded the same product. Meanwhile, with a small amount of water present in the Hg2Cl2/HgO-scCO2 system, at 200°C, 22000 kPa, the mineral terlinguaite (Hg4O2Cl2) was obtained instead of mercury oxide carbonate. Repeating this reaction under the same conditions, but in the absence of CO2, again resulted in the synthesis of terlinguaite, leading to the assumption that the scCO2 had no influence on the synthesis of terlinguaite. This study reveals a new moisture-free laboratory method and conditions for the permanent fixation of CO2 by HgO. This method bears two benefits: 1) it can be introduced to reduce the Hg content in flue gas and fly ash emitted from coal-burning power plants and municipal waste incinerators; 2) it can contribute to CO2 mineralisation in montroydite (HgO) geological formations as mercury oxide carbonate.

Cyclodextrins in Textile Finishing: Fixation and Analysis

Following a short overview of application of cyclodextrins (CDs) in textile finishing methods for the permanent fixation of CDs onto texiles and approaches to their quantitative analysis are reviewed. A new analytical method, based on the inclusion complexation of ferrocene, and a quantitative study, utilizing this method, on the covalent fixation, washing fastness and formaldehyde release of CD-containing finishes are presented. Ferrocene complexation is proven by Raman spectroscopy and by comparison with maltodextrin. Some of the finishing treatments resulted high yields and permanence against washing. Hydroxypropyl-CD reduced formaldehyde release and acted possibly as a formaldehyde scavenger. Using “low formaldehyde” crosslinkers ” requirements easily met.