Improving the properties of soil by stabilization is considered as a means of fulfilling design criteria. Stabilization is usually performed to improve material properties of soil such as strength, stiffness, and permeability. The use of new materials for soil strengthening is crucial for geotechnical engineering, especially in foundation construction. Experiments were conducted using resins with different epoxy resin-to-water (ER/W) ratios. . The results show that by increasing theresin in the soil, the maximum dry density increases, and the optimum water content decreases in the compaction tests.The results indicate that the epoxy resins improve the physical and mechanical properties of soil significantly, and if successfully grouted into a formation, the resins could provide a suitable solution for the stabilization of foundation material.
blocks were dried with a stream of warm air (45 ± 5 °C) generated from a blow dryer (model RV456ABG; Revlon, El Paso, TX, USA) for 15 s to approximately 15 cm from the surface. The air temperature was measured by digital portable thermometer (model MT 600; Minipa, São Paulo, SP, Brazil) with a resolution of 0.1 °C, a basic precision of 0.1 ± 0.7%, and with a temperature range from 0.1 to 200 °C. An etch-and-rinse adhesive system (Adper Single Bond 2; 3M ESPE) was applied according to manufacturer’s instructions: apply two coats of adhesive, air-drying for 10 s at 20 cm and light-curing for 10 s. After light curing ofthe adhesive system, 5 increments of 1 mm thickness of composite resin (Filtek Z250; 3M ESPE) were build-up. Each increment was light-cured with a halogen light-curing unit (VIP Junior; Bisco Inc., Schaumburg, IL, USA) for 40 s, with power density of 500 mW/cm 2 . The bonded ceramic blocks
affect the environment on one hand and use electricity or fossil fuel for its production on other [3-4]. Since aggregates and cement are costly on one hand and require higher transportation charges to supply them in the plains ofthe country. Hence, the use ofthe CSEB is considered to be neither economical nor environmentally friendly. As far as rammed earth is concerned, it is composed of cement as binding material, and aggregates as stabilizer water. Rammed earth walls on drying, may get cracked due to shrinkage causing weakness at several sections [5-19]. The objective of this study is to investigate potential use of compacted clay-pit sand blocks as replacement of CSEB and rammed earth in order to reduce construction cost and promote sustainable construction of houses without losing strength and durability.
For microwave post-polymerization heat treatment, the FS was also improved when compared with the nt group for both resins tested. These findings are supported by previous investigations that tested theeffectof microwave irradiation on autopolymerizing acrylic resins (Blagojevic et al.,1999; Patil et al., 2009; Vergani et al., 2005). Microwave postpolymerization reduced residual monomer, augmented the impact strength and improved the glass transition temperature (Tg) (Blagojevic et al., 1999). This may be explained by probably extension ofthe polymerization reaction produced by the heat generated during microwave irradiation resulting in the reduction ofthe residual monomer content (Patil et al., 2009; Seo et al., 2007; Takahashi et al., 2008). A monomer volatilization was also suggested for explaining the decrease in residual monomer and consequentially the improvement of mechanical properties (Bagis et al., 2000). Given that in the present study the specimens were placed in the microwave in a dry state, the diffusion mechanism that was mentioned to the water bath was not involved in the increasing of FS. Placing the specimens in water might lead to plasticization oftheresin, making it more flexible and resilient (Vergani et al., 2005), hence dry conditions were preferred. Although the two bis-acrylic resins tested showed better results of FS after heat treatment with microwave at 750 W for 1 minute, the results between the materials were different.
One ofthe faces of each ceramic block, with dimensions of 5x6mm, was planed out with water sandpapers with granulation of 300, 600, 800, 1000, 1200 to create a plane and uniform surface. Afterwards, each ceramic block was molded with addition silicone (Express - 3M Dental Products, St. Paul, MN - USA), in order to obtain an impression. This impression was used to make the blocks ofresin composite (Clearfil AP-XTM, Kuraray CO. - Japan) that were used to allow construction ofthe specimen. The blocks of composite resin presented one ofthe faces with similar characteristics to the planed faces ofthe ceramic blocks, providing a good contact between them. After impression, the planed faces ofthe ceramic blocks were conditioned with Rocatec system (ESPE, Seefeld - Germany), that comprises initial sandblasting with 110µm aluminum oxide particles (Rocatec- Pre), for 20 seconds with pressure of 2.8 bars, at a 10mm standard distance perpendicular to the surface, followed by further sandblasting with 30µm silica particles (Rocatec- Plus), which promotes formation ofthe silica layer, and at last, application ofthe silane coating (Rocatec-Sil).
were captured by a computer software (Leica Applica- tion Suite EZ; Leica Microsystems Ltd). Failure mode was recorded by a single calibrated observer as either adhesive (between metal and resin cement), cohesive (within theresin cement) or combination (areas of ad- hesive and cohesive failure). For this classification, the adhesive area was divided into quadrants, and in each of them, the predominant type of fracture was observed. According to the method of Santos et al. (14), the fracture was classified as adhesive or cohesive if either of these types predominated in 3 or more quadrants, and classi- fied as combination if 2 quadrants presented adhesive failure and the other 2 cohesive failure.
Figure 1 correlates, microhardness and tensile strength and the different LCUs and power densities are presented and coded. This figure depicts theeffectof LCU power density and exposure length. These data indicate that composite tensile strength was maximized by all LCUs. However, hardness values increased with increasing exposure duration. This result indicates that maybe the tensile strength is related to some critical flaw, which is not dependent onthe manner in which or extent to which the polymer network forms.
In this study, a control group (unmodified acrylic resin) and 5 experimental groups of acrylic resin modified with TBAEMA (batch number 126031013; Degussa Creavis, Marl, Germany) in different ratios were evaluated (Table 1). Denture base resin Lucitone 550 (batch number liquid 395100 and powder 66655; Dentsply Ind. e Com. Ltda, Petrópolis, RJ, Brazil) was used for all groups. each group (Table 1) was analyzed by XPS-eSCA (Kratos, Manchester, UK) to evaluate the presence of amino groups, represented by nitrogen ratios and submitted to flexural strength testing in a material testing system machine (Model 810; MTS System Corp, edden Praire, MN, USA).
For the flexural strengthofthe evaluated materials, the filler volume-fraction does not seem to be a decisive factor, as Filtek Z100 hybrid composite (71%) and Brilliant micro- hybrid composite (around 60%) exhibited statistically similar mean flexural strength values (141.7 MPa/127.7 MPa and 145.7 MPa/119.2 MPa, respectively). Assuming that during the flexural strength tests, the crack propagation in the specimen is intergranular (11), probably the chemical bonds promoted by silane coupling agent at resin-filler interface may also have influenced this mechanical property (19), promoting a balance between the composite resins, despite their different volume of filler particles. Filtek Z350 nanofilled and Opallis microhybrid composites showed significantly different flexural strength values between them (84.1 MPa/106.2 MPa and 85.2 MPa/83.7 MPa, respectively) and lower than Brilliant (145.7 MPa/119.2 MPa), although these three composite resins contain similar filler volume fraction. This fact demonstrates that the composition and degree of conversion oftheresin matrix, as well as the amount of filler particles are not the only factors affecting the mechanical strengthof restorative composites. The lower flexural strength value of Filtek Z350 nanofilled composite when compared to Filtek Z100 hybrid and Brilliant microhybrid composites was the result of a
Abstract: This study evaluated theeffectof mechanical cycling onthe bond strengthof zirconia posts to root dentin. Thirty single-rooted hu- man teeth were transversally sectioned to a length of 16 mm. The ca- nal preparation was performed with zirconia post system drills (Cos- moPost, Ivoclar) to a depth of 12 mm. For post cementation, the canals were treated with total-etch, 3-steps All-Bond 2 (Bisco), and the posts were cemented with Duolink dual resin cement (Bisco). Three groups were formed (n = 10): G1 - control, no mechanical cycling; G2 - 20,000 mechanical cycles; G3 - 2,000,000 mechanical cycles. A 1.6-mm-thick punch induced loads of 50 N, at a 45 ° angle to the long axis ofthe speci- mens and at a frequency of 8 Hz directly onthe posts. To evaluate the bond strengths, the specimens were sectioned perpendicular to the long axis ofthe teeth, generating 2-mm-thick slices, approximately (5 sections per teeth), which were subjected to the push-out test in a universal test- ing machine at a 1 mm/min crosshead speed. The push-out bond strength was affected by the mechanical cycling (1-way ANOVA, p = .0001). The results ofthe control group (7.7 ± 1.3 MPa) were statistically higher than those of G2 (3.9 ± 2.2 MPa) and G3 (3.3 ± 2.3 MPa). It was concluded that the mechanical cycling damaged the bond strengthof zirconia posts to root dentin.
So, examining the segregation behaviour ofthe alloying elements in ferrite and austenite one can conclude that Mo is the element that tends to segregate most heavily, while other elements reveal only a minor degree of segregation. It has been noticed that the values ofthe distribution coefficient for Mn and Ni, and for Mo, Cr and Si are changing with the increasing wall thickness of a stepped test piece. Only Cu does not follow this relationship.
Carbon steel C120U grade is largely used onthe tools for cutting, for dies and knives, for stamping and drawing tools, hobs, thread rolling tools and in many other applications due to her typical properties - high hardness, good toughness and compressive strength. The surface ofthe steel can be modified by using surface engineering's techniques. Remelting ofthe surface layer by the source of concentrated energy is promising technique to improve properties ofthe materials [1-6]. Laser or electron beam use to melting ofthe surface of tool steels aims to obtain a modified layer with increased microhardness and abrasion resistance [7,8]. The surface remelted layer has usually a finer and more homogenous structure than its original base material. The remelting with the arc plasma (TIG- tungsten inert gas or GTAW - gas tungsten arc welding) used as an economical and easily
Corporations need to address their social obligations more consciously. It is important to understand what kinds of responsibilities construct CSR before involving in any CSR act ivities. One widely acknowledged theory of CSR‘s components is Carroll‘s four-part theory. Carroll (1991) developed his four-part theory of CSR, arguing that CSR is constituted by four kinds of social responsibilities: economic, legal, ethical, and philanthropic responsibilities. The economic responsibilities are the primary part ofthe four responsibilities. It is the fundamental layer of Carroll‘s CSR pyramid. All corporations are responsible for providing goods and services that are needed by the society. Consequently, profits from selling goods and services go to shareholders and other investors to keep a company survive and grow. Economic responsibilities of a company are the base for providing legal, ethical and philanthropic responsibilities. Legal responsibilities are the second layer ofthe CSR pyramid and are coexisting with economic responsibilities as fundamental precepts ofthe free enterprise system. Firms are expected to operate under the legal system and regulations while creating profits for shareholders. Firms are fulfilling the "social contract" between firms and the society by being legally responsible. Legally responsible also reflects the "codified ethics" of business operation, as well as the pursuit of economic responsibilities set by lawmakers (Carroll, 1991). Ethical responsibilities involve activities and practices that are expected by the society and done by firms voluntarily regarding fair, justice and the respect for or protection of stakeholders' moral rights. Ethical responsibilities are voluntary choices of firms, since they are not codified into any law or regulation. These responsibilities reflect social norms, expectations and concerns of consumers, employees, shareholders and the community. Ethical responsibilities go further than legal responsibilities because they involve newly emerging values and norms that the public expects a firm to comply with and are at a higher standard of business practices than that current legal system required. However, ethical responsibilities are not easy to deal with for firms because new expectations from the public keep emerging and this makes the legitimacy of ethical responsibilities continually under debate (Carroll, 1991). Philanthropic responsibilities involve firms‘ activities that are
Materials & Methods: In total, 32 composite cylinders were provided from each ofthe two composites types (e.g., P90: P and Z350: Z). Cylinders were allocated to four different groups as follows: no surface treatments (Z1 and P1), silane application (Z2, P2), erbium laser irradiation (Z3, P3) and sandblasting with alumina particles (Z4, P4). Afterwards, the bonding component of P90 adhesive system was applied to all the prepared composite surfaces, followed by the repairing of all the samples with P90 cylinders. Moreover, SBS ofthe repaired surface was evaluated using the universal testing machine (UTM). Data analysis was performed using the one-way analysis of variance (ANOVA) and Tukey HSD (honest significant difference) test (P ≤0.05).
Enhanced recovery is so important in the petroleum industry that the location ofthe producer well is chosen with the secondary well (injection well) in mind. As mentioned before, efforts to enhance recovery are costly and are dependent upon the state ofthe economy and the potential oil recovery volume. Consequently, repeated monitoring of a reservoir is essential to choose the best locations for the injection wells. The idea is to design an optimal distribution of injection wells so as to optimize long-term production. There are several types of wells: wildcat well, rank wildcat well, step-out well, pro- ducer well, injection well, etc. Since there are different steps in the process of obtaining oil, wells are classified broadly as exploratory wells and development wells. Examples of exploratory wells are wildcat wells (drilled a mile or more from an area of existing oil production) and rank wildcat wells (drilled in an area where there is no existing produc- tion). If the exploratory drilling proves successful, the company starts to drill step-out wells (also included in the exploratory well category). After the oil field has been delin- eated, the company starts to drill production wells within the known extent ofthe field. Every well drilled inside the known extent ofthe field is called a development well (Hyne (2001)). The development well category includes producer wells and injection wells (re- call that injection wells are drilled to enhance oil recovery). Different categories of wells have different probabilities of finding oil. On average, rank wildcat exploratory wells have lower success ratio than step-out wells. An oil company can rank wells in terms of probability, even in the face of uncertainty. The American Petroleum Institute reported that in 2000 the success rate for wildcat wells was 39% (Hyne (2001)). Note that an unsuccessful drilling is classified as a dry hole in both exploratory and development well categories.
Relative advantage is defined as the extent to which a person views an innovation as offering an advantage over previous ways of performing the same task (Roger, 1983; Agarwal & Prasad, 1997). Because Internet banking services allow customers to access their banking account from any location 24 hours a day and 7 days a week, it provides an enormous advantage and convenience to users (Tan & Teo, 2000). It also gives customers greater control over managing their finances, as they are able to check their accounts easily. Besides, a customer’s Internet experience, his or her banking needs can affect his adoption. As there are more financial products and services, it is expected that individuals with many financial accounts and who subscribe to many banking services will be more inclined to adopt Internet banking. Tan and Teo (2000) has reported that potential adopters of Internet banking services are likely to own multiple banking accounts and subscribe to various banking services. Rogers argues that potential adapters, who are allowed to experiment with an innovation will feel more comfortable with the innovation and are more likely to adopt it. Thus, if customers have the opportunity to try the innovation, certain fears ofthe unknown may be minimized. Government policy could also aid or hinder Internet diffusion (Mbarika, 2002). This is consistent with the national systems of innovation theory that posits that government policies may encourage or mandate technology development and adoption (King et. al., 1994; Wolcott et. al., 2001). Tan and Teo (2000) suggest that the greater the extent of government support for Internet commerce, the more likely Internet banking will be adopted, thus, confirming Goh’s (1995) suggestion that governments can play an interventionist and leading role in the diffusion of innovation. Potential users in turn would view new applications such as Internet banking services more favorably and hence be more like to use them. Thus, the second alternative hypothesis is:
In paper is presented problem concerning inoculation of pure aluminium structure, which is realized mainly by intensification of liquid metal movement in mould. In aim of realization of forced movement during the crystallization of liquid metal was used rotate electromagnetic field, which is generated by induction coil fed with frequency of supply voltage from 25 to 100Hz. Effectof structure refinement obtained by influence of electromagnetic field was compared with refinement obtained by use of traditional inoculation, which consists in introducing of additions in form of titanium and boron to metal bath.
The advanced materials for future structural applications are intermetalics. Good mechanical properties, also at elevated temperatures, high resistance to oxidation and corrosion in aggressive environments, and high resistance to abrasion recommend intermetals with all their valuable performance properties to be used as a material for protective surface layers [9, 10, 11].
In the paper the 2D task concerning the continuous casting technology is discussed. Onthe basis ofthe knowledge of temperature history at the selected set ofthe points from the casting domain the boundary heat flux is identified [5, 6, 7]. The identification ofthe boundary heat flux in the primary cooling