Effect of physical and chemical operating parameters on anaerobic digestion of manure and biogas production: a review

Introduction: The need for food produced from animal husbandry has made it a growing industry which result in increment of livestock waste. On the basis of environmental and economic considerations, these materials require treatment and management. Anaerobic digestion and creation of biogas are the most effective methods of waste management. Several parameters affect the anaerobic digestion of animal wastes which should be studied in order to optimize the biogas production of reactors

Materials and Methods: The parameters affecting the performance of anaerobic processes in different scientific databases within 1984 -2016 were searched and related information were obtained

Results: A wide range of reactors with retention times of 0.5 to 140 days and organic loading rates from 0.11 to 7.5 grams per liter of organic matter in a day were studied based on the Volatile Solid [VS] in different temperature range. Also, studies conducted on mixing, co-digestion, changes in pH and ammonia content of the substrate, C/N ratio, as well as the effect of chemical interference were investigated

Conclusion: High COD removal decrease of VS were achieved in the range of 80-95 % and 65- 92 % respectively in bioreactors. The produced methane was also 48 mmol L[-1] to 4681.3 m[3] per month for reactors with a volume of 120 ml to 1330 m[3] achieved respectively at 37 and 55[degree]C from the Mesophilic and thermophilic temperatures. Results summarized on the physical and chemical conditions in this paper, can be used to study the effective parameters and optimize conditions used in biogas production

Lack of association between Cu T-380A intrauterine device and secondary infertility in Iran

Background: The appropriate choice of a contraceptive method has been a major issue in reproductive health research. Cu T intrauterine device [Cu T IUD] has been introduced as one of the most effective contraceptive methods in the world, however, the relationship between prior use of Cu T IUD and secondary infertility has not been evaluated in Iran. To examine the association of Cu T-380A IUD and secondary infertility in Iran

Materials and Methods: A retrospective cohort study was conducted from December 2010 to September 2011 in the Research and Clinical Center for Infertility, Shahid Sadoughi University of Medical Sciences, Yazd, Iran. A total of 750 married women [15-49 years old] with at least one parity, whom were referred to four educational healthcare centers of Shahid Sadoughi University of Medical Sciences, were selected as participants. They were divided into two groups [case and control] based on previous history of using Cu T-380A IUD. Data were gathered using a standard reliable questionnaire along with a face-to-face interview and were analyzed with descriptive and analytical [chi[2]] tests

Results: Mean period of Cu T-380A IUD usage in the case group was 57.46 +/- 47.74 months and mean time length from Cu T-380A IUD removal to pregnancy was 14.87 +/- 5.18 months in this group. We observed no relationship between the use of Cu T-380A IUD and frequency of secondary infertility [3.5% in the case group versus 2.7% in the control group, P=0.52]

Conclusion: Given the relatively large sample size studied here, it is unlikely that Cu T-380A IUD results in secondary infertility and may be used by Iranian women as a safe contraceptive method

The Effect of Soft and Rigid Cervical Collars on Head and Neck Immobilization in Healthy Subjects

STUDY DESIGN: Whiplash injury is a prevalent and often destructive injury of the cervical column, which can lead to serious neck pain. Many approaches have been suggested for the treatment of whiplash injury, including anti-inflammatory drugs, manipulation, supervised exercise, and cervical collars. Cervical collars are generally divided into two groups: soft and rigid collars. PURPOSE: The present study aimed to compare the effect of soft and rigid cervical collars on immobilizing head and neck motion. OVERVIEW OF LITERATURE: Many studies have investigated the effect of collars on neck motion. Rigid collars have been shown to provide more immobilization in the sagittal and transverse planes compared with soft collars. However, according to some studies, soft and rigid collars provide the same range of motion in the frontal plane. METHODS: Twenty-nine healthy subjects aged 18–26 participated in this study. Data were collected using a three-dimensional motion analysis system and six infrared cameras. Eight markers, weighing 4.4 g and thickened 2 cm² were used to record kinematic data. According to the normality of the data, a paired t-test was used for statistical analyses. The level of significance was set at α=0.01. RESULTS: All motion significantly decreased when subjects used soft collars (p<0.01). According to the obtained data, flexion and lateral rotation experienced the maximum (39%) and minimum (11%) immobilization in all six motions using soft collars. Rigid collars caused maximum immobilization in flexion (59%) and minimum immobilization in the lateral rotation (18%) and limited all motion much more than the soft collar. CONCLUSIONS: This study showed that different cervical collars have different effects on neck motion. Rigid and soft cervical collars used in the present study limited the neck motion in both directions. Rigid collars contributed to significantly more immobilization in all directions.