The Influence of Cement/Wood Ratio and Cement Type on Bending Strength and Dimensional Stability of Wood-Cement Composite Panels

This study examined the influence of decreasing cement/wood ratios from 3.0 to 1.5 at 0.5 increments on flexural and dimensional stability properties of cement-bonded composite panels. In addition, two types of Portland cement (I and III) were employed to assess if a difference exists in properties over time between the two types. Cure periods were reduced from 28 to 14 days to investigate whether significant reductions occur in these properties.Results indicate that modulus of rupture increases as the cement/wood proportion is lowered. A cement/wood ratio of 2.0 was found to demonstrate optimum bending strength. Modulus of elasticity, however, increased linearly with greater cement/wood ratios. Generally, wood-cement panels made in this study exhibited high dimensional stability when exposed to a 24-hour water soak. No significant differences were observed between the Lehigh cement types used in this study believed to be due to compound composition similarities. In most cases, reducing cure periods from 28 to 14 days had little influence on board properties

Wood-Cement Composites: Effect of Model Compounds on Hydration Characteristics and Tensile Strength

The development of wood-cement composite products is limited by cement's incompatibility with numerous wood species that inhibit cement setting and hardening. This study investigated the relative effects of specific model compounds commonly found in wood on the tensile splitting strength and hydration characteristics of Type I portland cement.Model compounds representing classes of wood components were added to cement at concentrations of 0.01, 0.10, and 1.00%. Glucose decreased cement tensile strength by nearly 50%. Quercetin, xylan, and acetic acid lowered tensile strength by a lesser amount. Wood components added to cement in 0.10% concentrations had a greater effect on strength than on exothermic behavior. Little correlation was found between tensile splitting strength and exothermic hydration characteristics (maximum hydration temperature, time to maximum hydration temperature, and relative heat generation). The relative difference in heat generation between an additive-cement sample and a cement standard was best able to distinguish differences among wood component effects

Effect of plant seeds protein extract on the Sunn pest, Eurygaste integriceps Puton, growth and development and its gut serine protease activity

The sunn pest Eurygaster integriceps Puton (Hemiptera: Scutelleridae) is a major pest of wheat and barley in wide areas of the world that cause 100% crop loss when no control measures are taken. The aim of this study was to investigate the effect of the seed proteinous extract of different plant species including Chickpea Cicer arietinum (Fabaceae), bean Phaseolus vulgaris var. naz (Fabaceae), triticale Triticosecale wittmack (Poaceae), Celosia argentea (Amaranthaceae) in artificial diet against the Sunn pest growth and development as well as gut serine proteinase such as trypsin and chymotrypsin activities. The obtained results showed that protease inhibitors present in the seed extract affected nymphal development, adult weight and survivability to some extent. Mean developmental time of third and fourth instar nymphs were not significantly affected by the presence of seed extracts. However, developmental time of the fifth instar nymph was affected by seeds proteinous extracts. Bean proteinous extract increased developmental time significantly by almost two days followed by Chickpea that increased developmental time by one day (P < 0.01). Amaranthus seed proteinous extract caused slight increase in development time. Triticale extract did not affect nymph growth and development and there were no significant differences between developmental time of triticale extract and control. Azocaseinolytic activity of gut extract of E. integriceps was affected greatly by seed proteinous extracts. There were significant differences in general protease activity between control and all treatments. General protease activity dropped significantly low when treated with bean and cowpea extracts (P< 0.01). Almost the same trend was observed when trypsin and chymotrypsin activities were measured using BApNA and SAAPFpNA as substrates, respectively. It is concluded that seed extracts from non host plants of the Sunn pest caused significant reduction of general and specific protease activity in vitro.Key words: Sunn pest, growth, development, seed extracts, protease activity

Effect of Various Treatments and Additives on Wood-Portland Cement-Water Systems

In this study, a series of treatments were considered to determine the impact of such treatments on wood-cement compatibility. These treatments included hot water extraction of water-soluble components in wood, and/or chemical additives. The species involved included lodgepole pine and western larch. The latter species, in a prior study, proved to be highly inhibitory in a series of hydration tests. The data presented in this paper show that substantial improvements in cement setting can be achieved by the removal of water-soluble extractives and sugars in western larch. Such improvements, however, did not take place in lodgepole pine, which data show is far less inhibitory than larch in the untreated state. The addition of chemical additives, especially calcium chloride, appears to enhance compatibility in cement-wood-water mixes

Construction of an internal amplification control for Mycobacterium tuberculosis polymerase chain reaction (PCR) test

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (MTB) which mostly affects the lungs. The disease causes deaths of many people every year. There are different methods to detect MTB such as skin test, staining, culture and molecular techniques. Polymerase chain reaction (PCR) is a simple and rapid method for the detection of MTB; however, positive and negative false results reduce the efficiency of this technique. The aim of this study was to design an internal amplification control (IAC) and apply it in MTB PCR test. PCR technique for MTB was optimized by using specific primers for IS6110 gene. The sensitivity and specificity of the test were determined. IAC was constructed with competitive strategy by PCR-cloning technique and the limitation range was determined. The PCR products of MTB and IAC were 245 and 660 bp, respectively on electrophoresis gel. The IC used in PCR testing of MTB is the competitive form in which the range was between 10 million and 10 bacteria and the most suitable internal control concentration for the mix was 1,000 plasmids. After making IC and using it in MTB amplification, it was observed that IC might guarantee the correctness of PCR reaction.Keywords: Mycobacterium tuberculosis, polymerase chain reaction (PCR), internal control.African Journal of Biotechnology Vol. 12(27), pp. 4277-428

Length-length, length-weight relationship and relative condition factor of pike, Esox lucius Linnaeus, 1758, in Anzali Wetland (Southwest of the Caspian Sea)

The length-length (LLRs), length-weight (LWR) relationships and relative condition factor (Kn) of 505 specimens of pike, (Esox lucius Linnaeus, 1798) from Anzali Wetland, southwest of the Caspian Sea, were studied from April 2012 through March 2013. The length-length relationships among total length (TL), fork length (FL) and standard length (SL) for pike were found to be highly significant (r2>0.986, P<0.001). The values of b in length-weight relationship in males (3.1495), females (3.1843) and for all specimens (3.2137) indicated isometric growth. Mean relative condition factor for male, female and all specimens were 1.003, 1.004 and 1.008 respectively. The result of LWR could be used for fishery managers to approve appropriate regulations for sustainable fishery management. Few studies have been conducted on these parameters of pike and this is the first report on LLRs, LWR and Kn of pike from Iranian waters

Complications and carcinogenic effects of mustard gas - A systematic review and meta-analysis in Iran

Background: Catastrophic effects of mustard gas as a chemical warfare agent have always been a major problem for those exposed to this agent. In this meta-analysis it was tried to evaluate carcinogenesis, ocular, cutaneous and respiratory complications of mustard gas exposure among Iranians who had been exposed to this agent during the Iran-Iraq war. Materials and Methods: In this meta-analysis, the required data were collected using keywords "mustard gas", "sulfur mustard", "cancer", "neoplasm", "respiratory complications", "ocular complications", "lung disease", "chronic complication", "eye", "skin", "cutaneous complication", "carcinogenesis" and their combination with keywords "Iran", "Iranian", "prevalence", "mortality" and their Farsi equivalent terms from the databases of SID, Iranmedex, Magiran, Pubmed, Science Direct, Google Search engine, Gray Literature and Reference of References. To determine the prevalence of each complication and perform meta-analysis, CMA: 2 (Comprehensive Meta-Analysis) software with a randomized model was used. Results: Of the 542 articles found, 7 national articles, consistent with the aims of this study were selected. Metaanalysis of seven papers revealed that cancer risk, especially cancer of the respiratory system was elevated, so that the relative risk (RR) of cancer role of mustard gas was inconsistent from 2/1 to 4 in this survey. Also prevalence of delayed skin disorders due to sulfur mustard was 94.6, pulmonary complications 94.5 and ocular complications 89.9. The incidence of various cancers in victims exposed to mustard gas was 1.7 worldwide where the rate was 2.2 in Iranian victims of the Iraq-Iran war. Conclusions: Based on present study the prevalence of delayed mustard gas related cutaneous, pulmonary and ocular complications is above 90 and risk of carcinogenesis is higher in comparison to worldwide statistics. This may suggest need for long-term and persistent follow-up and rehabilitation procedures es for populations exposed to this agent