Influence of drying time of adhesive systems on the bond strength between resin cement and feldspathic ceramic / nfluência do tempo de secagem de sistemas adesivos na resistência de união entre cimento resinoso e cerâmica feldspática

Objetivo: Este estudo se propôs avaliar o efeito de diferentes tempos de secagem de dois adesivos tipo ‘total-etch & rinse’ e ciclagem térmica na resistência adesiva entre cerâmica feldspatica e cimento resinoso. Material e Métodos: Trinta e dois blocos (12×10×4 mm) de cerâmica feldspática e respectivos blocos (32) de resina composta foram obtidos. A superfície de cimentação de cada bloco cerâmico foicondicionada por ácido fluorídrico (HF), silanizada (S), e recebeu a aplicação de um dos dois sistemas adesivos testados (SB - Single Bond 2, 3M-ESPE; ou PB – Prime & Bond NT, Dentsply). Então a superfície com o adesivo foi seca em diferentes tempos (5, 10 e 15s) antes da cimentação. Após, um cimento resinoso foi aplicado sobre a superfície de cimentação e o bloco correspondente de resina foi cimentado. Os palitos para microtração foram obtidos, sendo que metade deles foram imediatamente testados, enquanto os demais foram submetidos à ciclagem térmica e armazenagem (150 dias). Para os grupos sem envelhecimento, o tempo de secagem mais longo (15s) aumentou a resistência para o adesivo SB, enquanto que reduziu a resistência para o adesivoPB. Resultados: Para os grupos envelhecidos, as resistências adesivas dos diferentes tempos de secagem não foram diferentes estatisticamente, independente do adesivo. A falha predominante foi coesiva do cimento resinoso, seguido pela falha na interface cerâmica cimento. Conclusão: Conclui se que tempos mais longos de secagem podem melhorar a resistência adesiva à cerâmica testada, usando o adesivo SB. Por outro lado, tempos mais curtos podem otimizar a adesão para o adesivo PB. O envelhecimento afetou a adesão somente nos grupos do adesivo SB

Objective: This study evaluated the effect of drying times of two total-etch & rinse adhesives on the resin bond strength to a feldsphatic ceramic, before and after aging. Material and Methods:Feldsphatic-ceramic CAD-CAM bars were cut into blocks (12×10×4 mm) with a cutting machine (N = 32). Impressions were made of each ceramic block with silicone putty material and the negativespace was filled with a composite resin. The bonding ceramic surface was etched with hydrofluoric acid, silanized, and the adhesive system (SB- Single Bond 2, 3M-ESPE; or PB- Prime & Bond NT, Dentsply) was applied. The samples were dried at different times (5, 10 and 15 s) before the cementation. The resin and ceramic blocks were cemented bya dual cure resin cement. All samples were stored in distilled water at 37 °C for 24 h. For the μ-TBS test, the samples were sliced into microbars. Half of the bars of each block was tested after 24 h and, the other bars were submitted to thermocycling (12,000×) and water storage (150 d). For the 24 h groups, the longer drying time increased (p < 0.05) the bond strength of SB (water/alcohol adhesive), while reduced (p < 0.05) for the PB group (acetone based adhesive). Results: For the aged groups, the bond strength for the different drying times had no significant difference, for the both adhesives. Conclusion: Longer drying times increased the bond strength values of SB. Smaller drying times increased the bond strength values of PB. The aging protocol influenced the bond strength of SB groups.

Study of Potassium Solubilizing Bacteria from Limestone Mining Area in Palimanan, Cirebon Quarry

Aims: Potassium is an essential macronutrient for the growth and development of plants. Most of potassium in the soil presented in mineral forms or non-exchangeable forms which are not available for plants. The microbial activity facilitated to release of mineral forms or non-exchangeable potassium to the exchangeable or water-soluble. This study was aimed to isolate, select, and characterize of the selected potassium solubilizing bacteria from limestone mining area in Palimanan, Cirebon Quarry. Methodology and results: Isolation and selection of bacteria was done based on potassium dissolving index in Aleksandrov media containing feldspar, non-exchangeable potassium. Thirty seven isolates of potassium solubilizing bacteria were obtained in this study. Three isolates showed higher dissolution index, namely KQC.4B.1, KQC.5A.4, and KQC.5C.5. All of isolates were Gram negative bacteria, short-rod formed, and able to dissolve potassium concentration on 10th and 20th days. The three isolates showed 99.9% physiologically similar with Burkholderia cepacia. Futhermore by using 16S rRNA gene identification, isolate KQC.5C.5 closely related with B. cepacia with 99% identity. The application of isolate KQC.5C.5 on soil showed that the isolate was able to release the solution K formed after 10th day incubation. Conclusion, significance and impact of study: Potassium solubilizing bacteria (B. cepacia) could use as a biological fertilizer for providing potassium which is available to plants grown on reclamation area of limestone quarry.

Assessment of multifunctional biofertilizer on rice seedlings (MR 219) growth in a greenhouse trial

Aims: Food security and safety are current issues around the world. Rice is a staple food for a large portion of the world’s population, and in Malaysia around 2.2 million tonnes of rice were consumed annually. Fertilizer input is the key to increase rice production. Malaysian Nuclear Agency (Nuclear Malaysia) has developed multifunctional biofertilizer products in an effort to reduce dependency on chemical fertilizers for crop production. Methodology and results: Multifunctional biofertilizer products contain indigenous microorganisms that have desired characteristics, which include plant growth promoting, phosphate solubilising, potassium solubilising and enhancing N2- fixing activity were used in this study. These products were formulated as liquid inoculants, which is suitable for rice production. A greenhouse trial was conducted to evaluate the effectiveness of multifunctional biofertilizer on rice. Multifunctional biofertilizer products were applied singly and in combination with rock phosphate, feldspar and irradiated oligochitosan from a project by Forum for Nuclear Cooperation in Asia (FNCA), Japan. Plants that were given chemical fertilizers and plants not receiving fertilizer or biofertilizer products were used as controls. Fresh and dry weights of rice seedlings were determined. Application of multifunctional biofertilizer combined with irradiated oligochitosan (T3) resulted in significantly higher fresh weights (97.12 g) and dry weights (84.16 g) as compared to non-treated plants (77.39 g fresh weights and 69.56 g dry weights). The results suggested that application of multifunctional biofertilizer in combination with irradiated oligochitosan could increase rice growth. Conclusion, significance and impact of study: Combination of biofertilizer with oligochitosan increased rice growth in greenhouse trial. Further investigation of this interaction phenomenon should be carried out.

Quantitative Analysis of Quartz, Mica, and Feldspar in Respirable Coalmine Dust in Taebaek Area by Fourier Transform Infrared Spectrophotometry / 예방의학회지

A Fourier transform infrared spectrophotometric method was described for the determination of quartz, mica(sericite) and feldspar(potassium feldspar) in respirable dust in Taebaek area. The results were as follows; 1) The concentration of minerals were determined from the intensity of absorption peak of quartz at 799 cm-1, sericite at 539 cm-1, and potassium feldspar at 648 cm-1 respectively. 2) The precision(C. V. %) for the quartz determination was 7.70+/-2.68 % from 10 to 200 microgram of quartz. 3) The precision for the sericite determination was 16.34+/-6.82 % from 30 to 500 microgram of serictite. 4) The precision for the potassium feldspar determination was 5.28+/-1.74 % from 30 to 500 microgram of potassium feldspar. 5) The concentration of respirable dust in Taebaek area was 4.90+/-3.29 mg/m3(0.4-93.7%), percent quartz was 1.80+/-4.14% (0.01-20.56%), percent sericite was 11.37+/-6.43% (0.00-29.69%), percent potassium feldspar was 8.15 % (n=7, 3.41-19.70%). 6) The difference of respirable coal dust, quartz, and sericite concentration in drilling, coal cutting, hauling and separating was significant respectively (p<0.05).