fracture and microstructural study of bovine bone under mixed mode i ii loading

Abstract Understanding the fracture behavior and associated crack growth mechanism in bone material is an important issue for biomechanics and biomaterial researches. Fracture of bone often takes place due to complex loading conditions which result in combined tensile-shear (i.e. mixed mode) fracture mechanism. Several parameters such as loading type, applied loading direction relative to the bone axis, loading rate, age and etc., may affect the mixed mode fracture resistance and damage mechanism in such materials. In this research, a number of mixed mode I/II fracture experiments are conducted on bovine femur bone using a sub-sized test configuration called "compact beam bend (CBB)" specimen to investigate the fracture toughness of bone under different mode mixities. The specimen is rectangular beam containing a mid-edge crack that is loaded by a conventional three-point bend fixture. The results showed the dependency of bone fracture toughness on the state of mode mixity. The fracture surfaces of broken CBB specimens under different loading conditions were studied via scanning electron microscopy (SEM) observations. Fracture surface of all investigated cases (i.e. pure mode I, pure mode II and mixed mode I/II) exhibited smooth patterns demonstrating brittle fracture of bovine femur. The higher density of vascular channels and micro-cracks initiated in the weakened area surrounded by secondary osteons were found to be the main cause of the decreased bone resistance against crack growth and brittle fracture

Chronic health effects of sulphur mustard exposure with special reference to Iranian veterans

The widespread use of sulphur mustard (SM) as an incapacitating chemical warfare agent in the past century has proved its long-lasting toxic effects. It may also be used as a chemical terrorist agent. Therefore, all health professionals should have sufficient knowledge and be prepared for any such chemical attack. SM exerts direct toxic effects on the eyes, skin, and respiratory tissue, with subsequent systemic action on the nervous, immunological, haematological, digestive, and reproductive systems. SM is an alkylating agent that affects DNA synthesis, and, thus, delayed complications have been seen since the First World War. Cases of malignancies in the target organs, particularly in haematopoietic, respiratory, and digestive systems, have been reported. Important delayed respiratory complications include chronic bronchitis, bronchiectasis, frequent bronchopneumonia, and pulmonary fibrosis, all of which tend to deteriorate with time. Severe dry skin, delayed keratitis, and reduction of natural killer cells with subsequent increased risk of infections and malignancies are also among the most distressing long-term consequences of SM intoxication. However, despite a lot of research over the past decades on Iranian veterans, there are still major gaps in the SM literature. Immunological and neurological dysfunction, as well as the relationship between SM exposure and mutagenicity, carcinogenicity, and teratogenicity are important fields that require further studies, particularly on Iranian veterans with chronic health effects of SM poisoning. There is also a paucity of information on the medical management of acute and delayed toxic effects of SM poisoning—a subject that greatly challenges health care specialists

Chemical composition and evaluation of antimicrobial properties of Rosmarinus officinalis L. essential oil

Preservatives used in the food industry are undergoing increasing scrutiny and reappraisal. There is therefore a renewed interest in the antimicrobial properties of herbs and spices. Rosemary (Rosmarinus officinalis L.) belonging to the Lamiaceae family, is a pleasant-smelling perennial herb. The antimicrobial activities of the R. officinalis oil against Leuconostoc mesenteroides (PTCC1591), Lactobacillus delbruekii (PTCC1333), Saccharomyces cerevisia (PTCC5269) and Candida krusei (PTCC 5295) were determined. The results indicate that among the tested microbes, the essential oil had a stronger inhibitory effect on the bacteria as compared to yeasts. Minimum inhibitory concentration (MIC) values for bacteria L. mesenteroides, L. delbruekii, S. cerevisia and C. krusei ranged between 0.5 and 1.5 mg/ml. The oil was analyzed by GC and GC/MS. The major components of R. officinalis oil were 1,8-cineole (23.14%), camphor (12.35%), α-pinene (9.87%), β-pinene (6.10%), borneol (5.61%), camphene (5.58%) and α-terpineol (4.30%), respectively. These results indicate the latent potency of essential oil of R. officinalis as a natural preservative in food products against L. mesenteroides, L. delbruekii, S. cerevisia and C.krusei.Key words: Rosmarinus officinalis L., essential oil, chemical composition, antimicrobial properties

Community composition and diversity of zooplankton in the northwest Persian Gulf

Survey on zooplankton composition was studied during June 2015 to March 2016, by selecting six stations along the coastal waters of Bushehr (the Northwest Persian Gulf). Twenty four zooplankton taxa were identified, and the different zooplankton groups represented twenty-one families. Copepoda was recorded with the most abundance (53.30 %) followed by Malacostraca (32.87 %), which in turn was followed by Sagittoidea (7.44 %) and Appendicularia (6.39%). A major peak of 189.34 N/m3 was observed in February-2016 with 53.25% contribution from Copepoda. Among Copepoda, Labidocera sp. was the major contributor to this peak. Appendicularia was the comparatively less represented group, being chiefly represented by Oikopleura dioica. Labidocera sp., Oithona plumifera which were common in most of the stations. This common distribution were observed for Malacostraca, namely Lucifer hanseni (mysis I), Upogebia sp. (zoea I), Parthenope sp., Ilyoplax frater( zoea VI), for Sagittoidea, namely Sagitta enflata, Sagitta neglecta and for Appendicularia, namely Oikopleura dioica. The mean Shannon's diversity index (H') and evenness were 1.36±0.43 and, 0.68±1.17, respectively. The highest Margalef's index was recorded in station-6 (2.72±1.32) and the lowest in station-2 (1.98±0.89). According to non-significant differences between temporal and spatial zooplankton density and Shannon’s index, from an ecological point of view, it seems the study area is unique and the zooplankton composition is homogenous

Parasites of some bonyfish species from the Boojagh wetland in the southwest shores of the Caspian Sea

The Boojagh international wetland with a surface area of 80 hectares and 25 fish species is located in the southwest shores of the Caspian Sea (Guilan province, Iran), but there is no report about fish parasites in this wetland. In the present study, a total of 553 individuals of 8 fish species including Cyprinus carpio (n=71), Abramis bjoerkna (n=153), Carassius auratus gibelio (n=89), Esox lucius (n=39), Rutilus rutilus caspius (n=36), Rutilus frisii kutum (n=81), Scardinius erythrophthalmus (n=119) and Tinca tinca (n=4), were collected in October 2001 through November 2003. Eight parasite species were identified in the fishes consisting of 1 nematode: Raphidascaris acus (in E. lucius and S. erythrophthalmus); 1 cestode: Caryophyllaeus fimbriceps (in R. rutilus caspius and C. carpio); 2 digenean trematodes: Asymphylodora tincae (in T. tinca) and Diplostomum spathaceum (in all of the fish species except for T. tinca and S. erythrophthalmus); 2 monogenean trematodes:Tetraonchus monenteron (in E. lucius) and Dactylogyrus sp. (in C. carpio, A. bjoerkna and C. auratus gibelio); 1 crustacean: Lernaea cyprinacea (in A. bjoerkna, T. tinca and R. rutilus caspius) and 1 leech : Piscicola sp. (in R. rutilus caspius and C. carpio). The occurrence of R. acus in S. erythrophthalmus and also that of C. fimbriceps in R. rutilus caspius are reported for the first time as new host records

Occurrence and intensity of parasites in pike (Esox lucius) in River of Chamkhaleh

Pike (Esox lucius) of Chamkhaleh River in Langrood (Iran) was studied from winter 2003 to autumn 2004. We collected 123 specimens of the fish and sent them live to the lab for examinations. Biometrical measurements, age and sex determination were conducted on the samples. The eye, skin, gill, digestive system, muscle and other organs of the specimens were examined for parasite infestation. Seven parasites: Raphidascaris acus, Camallanus lacustris, Diplostomum spathaceum, Tetraonchus monenteron, Triaenophorus crassus, Corynosoma strumosoum, Lernaea sp. were found in the pikes of the Chamkhaleh River. The most prevalent parasite was R. acus (37.39%) and the least were C. strumosum and Lernaea sp. (0.81% each). The highest mean intensity of the parasites was related to T. crassus (8.45 specimens) and the lowest was detected for Lernaea sp. (0.01). The highest range in parasite infection was seen for R. acus (1-45) and the lowest for Lernaea sp. with only one individual parasite. We observed seasonal, age and sex differences in infection rate with the parasites. This is the first time report of the pike as a host for C. strumosum

Providing database of Iranian fish larvae under Iranian fisheries research organization net work

This project prepared and implemented during 2013-16 with emphasis on to provide the results of the fish larva projects (identification, abundance and distribution) in the Iranian waters of the Persian Gulf and Gulf of Oman which as well as had already been done by Iranian Fisheries Science Research Institute and affiliated research institutes and centers . Since each marine fish stocks management requires increased knowledge of the life cycle and be complete biological information, obviously implementation and increased field research is essential, on the other hand the results and the availability of data and information to operation and coordination with the scientific community at national and international levels is of particular importance. This is on condition that currently, due to the increasing trend researchers and students Aquatic Sciences and Fisheries, the availability of data resulting from studies and research projects and initiatives will be necessary. The site is currently only in view of identification and distribution of marine fish larva has been prepared in Farsi with photo gallery, and English language development and preparation of the site for the international operation there. It is worth mentioning in the same areas and the same site adjacent seas of fish larvae has not been prepared and is not available. So this site can also be considered as reference area. This site is available for researchers, scientist and students as address: http://ifl.ifro.ir