Behavioral thermoregulation in the American lobster Homarus americanus

It is generally accepted that water temperature has a strong influence on the behavior of the American lobster Homarus americanus. However, there is surprisingly little behavioral evidence to support this view. To haracterize the behavioral responses of lobsters to thermal gradients, three different experiments were conducted. In the first, 40 lobsters acclimated to summer water temperatures (summer-acclimated, 15.5±0.2 °C, mean ±S.E.M.) were placed individually in an experimental shelter, and the temperature in the shelter was gradually raised until the lobster moved out. Lobsters avoided water warmer than 23.5±0.4 °C, which was an increase of 8.0±0.4 °C from ambient summer temperatures. When this experiment was repeated with lobsters acclimated to winter temperatures (winter-acclimated, 4.3±0.1 °C), the lobsters (N=30) did not find temperature increases of the same magnitude (∆T=8.0±0.4 °C) aversive. The second experiment was designed to allow individual summer-acclimated lobsters (N=22) to select one of five shelters, ranging in temperature from 8.5 to 25.5 °C. After 24 h, 68 % of the lobsters occupied the 12.5 °C shelter, which was slightly above the ambient temperature (approximately 11 °C). In a similar experiment, winter-acclimated lobsters (N=30) were given a choice between two shelters, one at ambient temperature (4.6±0.2 °C) and one at a higher temperature (9.7±0.3 °C). Winter-acclimated lobsters showed a strong preference (90 %) for the heated shelter. In the final experiment, summer-acclimated lobsters (N=9) were allowed to move freely in a tank having a thermal gradient of approximately 10 °C from one end to the other. Lobsters preferred a thermal niche of 16.5±0.4 °C and avoided water that was warmer than 19 °C or colder than 13 °C. When standardized for acclimation temperature, lobsters preferred water 1.2±0.4 °C above their previous ambient temperature. Collectively, the results of these studies indicate that lobsters are capable of sensing water temperature and use this information to thermoregulate behaviorally. The implications of these findings for lobster behavior and distribution in their natural habitat are discussed

Synthesis of some organotin monomers and copolymerisation with acrylic monmers

The aim of this thesis was to synthesise new organotin monomers based on Nsubstituted acrylamide and methacrylamide and on acrylic acid and methacrylic acid esters with pendant hydrolysable organotin moieties and to study their copolymerisation with methyl acrylate (MA), butyl acrylate (BA) and methyl methacrylate (MMA). A specific objective was to obtain suitable macromolecular chains, to which the organotin moieties could be attached at some distance from the main backbone. The new organotin monomers which were synthesised are: m-acrylamidotri-n-butyltin benzoate (m-AATBTB), p-acrylamidotri-n-butyltin benzoate (p-AATBTB), m-methacrylamidotri-n-butyltin benzoate (mMAATBTB), p-methacrylamidotri-n-butyltin benzoate (p-MAATBTB), 0- acryloyloxytri-n-butyltin benzoate (o-AOTBTB) and o-methacryloyloxytri-nbutyltin benzoate (o-MAOTBTBO). These were prepared by the reaction of bis(tri-n-butyltin) oxide (TBTO) with the corresponding acrylamide or acryloyloxy benzoic acid which were prepared by the reaction of aminobenzoic acid derivatives or salicylic acid with either acryloyl chloride or acrylic anhydride. These organotin monomers were polymerised in dimethylformamide (DMF) solution with azobisisobutyronitrile (AIBN) as initiator. Binary copolymerisation experiments were performed by solution polymerisation in DMF solution with AIBN as initiator. The copolymer composition in each case was determined from tin analysis. Since the properties of these organotin polymers are related to the distribution of monomer units, it is of great interest to determine the actual monomer reactivity ratios which control the sequence length distribution. Monomer reactivity ratios were calculated by the KelenTudos method. All of these organotin polymers and copolymers were characterised by Nuclear magnetic resonance spectroscopy (NMR) and Fourier Transform infrared spectroscopy (FTIR) methods, gel permeation chromatograghy (GPC) and dynamic mechanical thermal analysis (DMTA)

Applications of Compound Nanotechnology and Twisted Inserts for Enhanced Heat Transfer

Nanoadditives are a type of heat transfer enhancement techniques adopted in heat exchangers to improve the performance of industrial plants through improvement of the thermal properties of base fluids. Recently, various types of inserts with nanofluids are adopted to enhance the thermal performance of double pipe heat exchangers. In the current article, TiO2/water nanofluid with multiple twisted tape inserts was investigated as a hybrid enhancement technique of heat transfer in straight pipes. The investigations were carried out experimentally and numerically at Reynolds numbers varied from 5000 to 20,000. Using nanofluid with 0.1% TiO2 nanoparticles volume fraction demonstrated enhanced heat transfer with slight increase in pressure drop. Results are showing a maximum increase of 110.8% in Nusselt number in a tube fitted with quintuple twisted tape inserts with 25.2% increase in the pressure drop. However, as the article is representing a part of specified book on heat exchangers, the literature has been extended to provide sufficient background to the reader on the use of nanotech, twisted inserts, and hybrid of compound nanofluids and inserts to enhance heat transfer processes

ROLE OF THE PHYSICAL ACTIVITY IN THE IMPROVEMENT OF CARDIAC MEASURES AND DECLINING OF COMORBIDITIES.

Background: Regular physical activity (PA) can prevent many non-communicable diseases, such as cardiovascular disease (CVD) and diabetes mellitus (DM). The present study aimed to assess the health benefits of physical activities including blood pressure and comorbid conditions. Methodology: This is a prospective cohort case-control study that recruited 300 Saudi volunteers living in the city ofHail, Northern Saudi Arabia. Results: Out of 300 participants 155(51.7%) were males and 145 (48.3%) were females. There were 111(37%) participants committed to regular physical activity and the remaining 189(63%) without a defined commitment to physical activity (Uncommitted). Among 111 persons who claimed a commitment to regular physical activity (committed), 61(55%) were males and 50(45%) were females. The majority of committed individuals were at the age group 21-25 years followed by age group 26-30 and 31-35 years representing 32, 30, and 20 persons, respectively. The physical activity was highly practiced at the age range 21-30 years and this was found to be statistically significant P < 0.001. Conclusion: There is a low prevalence of physical activity in Hail region, particularly among females, which necessitates the suggestion of appropriate awareness programs. Younger and elder populations are in much need to be targeted with PA awareness programs

Recent methods in the production of activated carbon from date palm residues for the adsorption of textile dyes: A review

Textile dyes are organic compounds that can pose an environmental threat if not properly treated. They can cause many problems ranging from human health, ecosystem disturbances, and the reduction of the esthetic value of water bodies. The adsorption process using activated carbon (AC) has been proven to be effective in treating dyes in wastewater. However, the production of AC is limited by the non-renewables and relatively expensive precursor of coal. Date palm residues (DPRs) provide a good alternative for AC’s precursor due to their continuous supply, availability in a large amount, and having good physiochemical properties such as high oxygen element and fixed carbon. This study provides a review of the potential of date palm residues (DPRs) as AC in adsorbing textile dyes and the recent technological advances adopted by researchers in producing DPR-based AC. This review article focuses solely on DPR and not on other biomass waste. This study presents a background review on date palms, textile dyes, biochar, and AC, followed by production methods of AC. In the literature, DPR was carbonized between 250 and 400°C. The conventional heating process employed an activation temperature of 576.85–900°C for physical activation and a maximum of 800°C for physicochemical activation. Chemical agents used in the chemical activation of DPR included NaOH, KOH, ZnCl2, H3PO4, and CaCl2. The maximum surface area obtained for DPR-AC was 1,092.34 and 950 m2/g for physical and chemical activation, respectively. On the other hand, conditions used in microwave heating were between 540 and 700 W, which resulted in a surface area of 1,123 m2/g. Hydrothermal carbonization (HTC) utilized carbonization temperatures between 150 and 250°C with pressure between 1 and 5 MPa, thus resulting in a surface area between 125.50 and 139.50 m2/g. Isotherm and kinetic models employed in the literature are also discussed, together with the explanation of parameters accompanied by these models. The conversion of DPR into AC was noticed to be more efficient with the advancement of activation methods over the years.King Abdulaziz City for Science and Technology - grant no. 13-ENV1102-02

Inverse Correlation between Stress and Adaptive Coping in Medical Students

BACKGROUND: Medical students in their academic years are generally under stress but very few studies revealed the relationship between the stress and how the students manage to adapt these stressful conditions. AIM: The aim of the study was to investigate the levels of stress and their adaptive coping in the 1st 3 years medical students and also to determine the factors associated with adaptive coping strategies. METHODS: This is a descriptive cross-sectional study conducted on 441 medical students of Qassim University from September-October 2019. First 3 years medical students were randomly selected and their stress levels or adaptive coping strategies were determined by general health questionnaire (GHQ-12) and strategies coping mechanisms (SCM), respectively. The 5-points Likert scale was used for scoring and the data obtained were further validated by DASS and Brief COPE scales. RESULTS: Out of 441 medical students, 39.2% agreed to participate. The data showed that the level of stress among students was highest during their 1st year academic blocks, followed by 2nd and 3rd year students. Interesting, the adaptive coping among them was found highest during the academic blocks of 3rd year students, followed by the 2nd and 1st year students. Importantly, female students showed better adaptation against stress. Students living with their parents avoided stress in better ways as compared to those who were living alone. CONCLUSION: This is the first study that shows an inverse correlation between the stress and adaptive coping in medical students of Qassim University. The data concluded that adaptation of stress in the 3rd-year students was the highest followed by 2nd and 1st year medical students. Moreover, female students adapted well against stress and students living alone showed worse adaptation of stress