Hydroxyapatite Whiskers Based Resin Composite versus Commercial Dental Composites: Mechanical and Biocompatibility Characterization

A systematic evaluation of mechanical and biocompatibility properties of different volume fractions of hydroxyapatite whiskers in comparison with three commercial dental composites filled with micro- and nanosilica particles was carried out. Six groups with different hydroxyapatite whiskers mass fractions were taken into account in order to be compared with the performances of silica particles based composites group. Flexural properties were evaluated via a universal testing machine (2.5 kN Zwick Line) with a 2 kN load-cell (sensitivity 0.001 N). The test was replicated 10 times for the seven experimental groups to better identify statically the significance of the mechanical performances data. MTT quantitative colorimetric assay was performed in order to evaluate the mitochondrial activity of living cells exposed to different resin composites. Data obtained show better interfacial interaction with filler/matrix until 20 wt% of hydroxyapatite whiskers partially replaced silica particles filler. After this threshold, the mechanical performances decrease dramatically due to both the hydroxyapatite agglomerates formation and the low degree of resin conversion. In addition, biocompatibility test showed less cytotoxic effect with the addition of 20 wt% of hydroxyapatite in comparison with higher rates

Drinking water quality and identification of fluoritic areas in Machinga, Malawi

There is prevalence of dental fluorosis in certain parts of Machinga District that can be attributed to elevated drinking water fluoride content in the areas. Therefore, it is important to know the actual quality of water within the district and identify specific fluoride endemic areas that may require immediate adoption of remedial measures to manage the water resource and thus protect consumers. In this study, drinking water samples were collected from boreholes and pipes at 23 sampling sites, mostly villages within the district, for fluoride and other water physicochemical parameters during dry and rainy seasons of 2004 and 2005 respectively. Fluoride endemic sites were identified from the fluoride data. A survey of school children was also done in order to examine symptoms of dental fluorosis. Levels of fluoride ranged from 0.35 to 10.30 mg/L with 70 % of the sites sampled indicating levels above the World Health Organization (WHO) guideline of 1.50 mg/L. Fluoride endemic areas were identified as those villages around Mtubwi F.P School and Liwonde L.E.A School. This finding was supported by the prevalence of a high proportion of dental fluorosis in standard 3 and 4 pupils in these two schools. Values of pH ranged from 6.70 to 9.37; electroconductivity from 1950 to 31000 mS/cm; turbidity from 0.00 to 2.41, Formazin Turbidity Units (FTU); phosphates from 0.0 to 1.88mg/L; nitrates from trace to 58 mg/L; hardness from 1.08 to 276 mg CaCO3/L; sulphates from 6.09 to 109.98 mg/L; chlorides from 0.003 to 0.576 mg/L; carbonates from 2.01 to 85.30 mg/L and bicarbonates from 51.02 to 677.52 mg/L. Correlation of fluoride with other drinking water parameters was assessed using simple graphical methods. Positive correlation was observed between concentrations of fluoride with pH, total dissolved solids and carbonates, while phosphates correlated negatively with the fluorides. No correlation was observed between concentrations of fluoride with nitrates, electroconductivity, total hardness, carbonates and chlorides.Keywords: Machinga; fluoride; fluorosis; physicochemical parameter

Determining noise and vibration exposure in conifer cross-cutting operations by using Li-Ion batteries and electric chainsaws

In many activities, chainsaw users are exposed to the risk of injuries and several other hazard factors that may cause health problems. In fact, environmental and working conditions when using chainsaws result in workers' exposure to hazards such as noise, vibration, exhaust gases, and wood dust. Repeated or continuous exposure to these unfavourable conditions can lead to occupational diseases that become apparent after a certain period of time has elapsed. Since the use of electric tools is increasing in forestry, the present research aims to evaluate the noise and vibration exposure caused by four models of electric chainsaws (Stihl MSA160T, Stihl MSA200C Li-Ion battery powered and Stihl MSE180C, Stihl MSE220C wired) during cross-cutting. Values measured on the Stihl MSA160T chainsaw (Li-Ion battery) showed similar vibration levels on both right and left handles (0.9-1.0 m s-2, respectively) and so did the other battery-powered chainsaw, the Stihl MSA200C (2.2-2.3 m s-2 for right and left handles, respectively). Results showed a range of noise included between 81 and 90 dB(A) for the analysed chainsaws. In conclusion, the vibrations and noise were lower for the battery chainsaws than the wired ones, but, in general, all the values were lower than those measured in previous studies of endothermic chainsaws

Forest road planning, construction and maintenance to improve forest fire fighting: A review

Forest roads play a key-role in fire fighting activities. In fact, all ground-based activities are strictly related to the presence of forest roads as access to fire edge. In spite of this important role, forest roads are often planned and built without considering their use in fire fighting, and this also occurs in literature, where few studies are dedicated to the importance of forest roads in fire fighting. A well-developed and well-maintained forest road network is the answer to different needs in fire management. The objective of this review is to clarify basic principles for obtaining efficient road network also for fire fighting, collecting, defining and resuming the main roles, the most important aspects and the reported experiences to be taken into account in forest road network planning and maintenance in fire-prone areas. The most important themes treated are related to: i) the analysis of the functions of forest roads in fire prevention and suppression; ii) the importance of forest road planning and building also considering their importance for protecting forests against fires: iii) the construction and maintenance characteristics to be considered for building and maintaining an efficient forest road network against fires; iv) the importance of fire prevention and the related role of forest roads. Special attention has been dedicated to maintenance activities, because a not well-maintained forest road is a not efficient forest road, and it represents a useless economic and environmental cost

Wetland spirits and indigenous knowledge: Implications for the conservation of wetlands in the Peruvian Amazon

Globally, the importance of indigenous and local knowledge systems for science, policy, environmental conservation and the cultural heritage of indigenous peoples is increasingly being recognised. The Amazon region in particular is home to many indigenous peoples who have conserved their cultural traditions and knowledge, despite growing threats to the environment and traditional lifestyles and cultures. Based on insights from ethnographic research in three indigenous communities, here we present a case study on the indigenous knowledge of the Urarina people of the Chambira Basin in the Peruvian Amazon and its implications for conservation. We describe, for the first time, a series of anthropomorphic and territorial “wetland spirits”, who are associated with particular wetland ecosystems and range in character from the benign to outright aggressive. Their presence may indirectly benefit conservation of wetlands, as humans fear or respect these wetland spirits and adapt their behaviour accordingly. While benign spirits may be seen as positive models to follow, aggressive spirits may deter unsustainable harvesting of resources through fear of disease or death. However, their cultural status is not adequately captured by such rational-scientific explanations. Wetland spirits are important characters within the indigenous cosmos of humans and non-humans, which is built on a relational, rather than extractive model of connecting humans and nature. We discuss our findings in the context of wider conceptual debates on recognising relational ontologies in environmental policy and conservation, the paradigm of biocultural conservation, as well as their implications for land titling, and incorporating indigenous perspectives in local education

WWU Lifestyles Project Follow-up: Patterns of Alcohol and Drug Consumption and Consequences among Western Washington University Students

Executive Summary: In response to both internal and national findings and concerns, the first Western Washington University Lifestyles Project Survey of alcohol and drug usage among Western students was conducted in 1992 as part of the University\u27s on-going effort (a) to investigate students\u27 college experience both in and out of the classroom; (b) to enhance those experiences which lead to personal and academic success; and (c) to reduce risk factors jeopardizing student success. The 1995 WWU Lifestyles Project Survey follow-up has the same goals as its predecessor. Both surveys were administered to random samples of students across all years in school (freshmen through senior). Demographically, the 1995 survey cohort of 489 respondents I mirrored the overall population of 1995 Western students by gender, ethnicity, and age. In the 1992 report, researchers concluded that three patterns of alcohol use existed among Western students: 1) a sizable number reported no-to-low drinking patterns, with nearly a quarter reporting not drinking at all; 2) among drinkers only, about a third reported typical drinking patterns best described as moderate; and 3) also among drinkers only, patterns emerged that would be considered heavy drinking, with nearly a third of drinkers indicating they binged on typical occasions, and nearly two-thirds indicating they binged on peak occasions. For the most part, national findings were similar. Generally, drinking patterns changed little between 1992 and 1995; however, there were some encouraging trends to note. For one, though students in 1995 did not report drinking any less frequently, they did appear to be drinking in lesser quantities than they were in 1992. For instance, the percentage of students who drank seven or more drinks on typical occasions fell 1.7% (from 16.3% in 1992 to 14.6% in 1995), while the percentage of students who drank seven or more drinks on peak occasions fell 6.8% (from 40.6% in 1992 to 33.8% in 1995). Furthermore, the percentage of students who had five or more drinks on typical occasions remained nearly the same (33.8% in 1992 vs. 34.1% in 1995). These changes in the quantity of student drinking come at a time when the use of alcohol is beginning to see increases at the high school level. For instance, findings from Western\u27s 1995 was the first year since 1981 that there increases rather than decreases in the percentage of college-bound high school seniors indicating they had drank beer, wine, or liquor. For alcohol and drug abuse prevention programs, such trends might forebode even harder work ahead. The 1995 Lifestyles Survey found that not as many students indicated experiencing a negative effect due to drinking--down 3.0% from 1992. Promising also was the higher percentage of students indicating that they had never driven after two, or after four drinks. However, even though fewer students in 1995 indicated experiencing no negative effects due to alcohol use, certain findings indicated that those who did experience negative effects may have had more negative experiences than students in 1992; for instance, the Rutgers Alcohol Problem Inventory (RAPI) mean, a measure of overall negative effects due to alcohol, was up slightly from 4.3 in 1992 to 4.5 in 1995. It may be, however, that current survey students who experienced and possibly had slightly more negative effects due to alcohol use may continue, like they did in 1992, to be unable to recognize the negative effect alcohol may be having in their lives. Findings from the 1995 survey indicated that while only 3.1% of respondents indicated any likelihood of drinking impairing their ability to complete homework assignments, 18.1% indicated that they had experienced at least one incident where they were unable to study for a test or complete homework due to drinking. This percentage of difference of 15.0% was higher than the 12.4% discrepancy found for 1992 survey respondents. There is, in other words, some indication that students have a blind spot when it comes to their perception of how alcohol may impair their academics. Regarding drug usage, the most important finding that emerged was that more students in 1995 indicated they had used marijuana than in 1992. At this point, use remains relatively infrequent, with only 6.4% indicating they used marijuana more often than 2-3 times a month. Yet like alcohol use, there appears to be more acceptance of marijuana use than there has been in the past. Findings from Western\u27s 1995 survey of in-coming freshmen indicated the highest percentage of freshmen since 1976 support the idea of legalizing marijuana (44.2% compared to the all-time low of 16.4% in 1989). Regarding sexual activity, students continue to feel that they are not particularly at risk of either sexually transmitted diseases (STD\u27s) or pregnancy. Well over forty percent of students indicated they never used condoms when they had sexual intercourse, and well over sixty percent did not use a condom during their most recent sexual intercourse. And while few students indicated that they had had unwanted sex, for those students who had, most were females. On those occasions when a student had unwanted sex, alcohol was involved about a third of the time

Global hybrids from the semiclassical atom theory satisfying the local density linear response

We propose global hybrid approximations of the exchange-correlation (XC) energy functional which reproduce well the modified fourth-order gradient expansion of the exchange energy in the semiclassical limit of many-electron neutral atoms and recover the full local density approximation (LDA) linear response. These XC functionals represent the hybrid versions of the APBE functional [Phys. Rev. Lett. 106, 186406, (2011)] yet employing an additional correlation functional which uses the localization concept of the correlation energy density to improve the compatibility with the Hartree-Fock exchange as well as the coupling-constant-resolved XC potential energy. Broad energetical and structural testings, including thermochemistry and geometry, transition metal complexes, non-covalent interactions, gold clusters and small gold-molecule interfaces, as well as an analysis of the hybrid parameters, show that our construction is quite robust. In particular, our testing shows that the resulting hybrid, including 20\% of Hartree-Fock exchange and named hAPBE, performs remarkably well for a broad palette of systems and properties, being generally better than popular hybrids (PBE0 and B3LYP). Semi-empirical dispersion corrections are also provided.Comment: 12 pages, 4 figure

Twins Bed Rest Project: LBNP/Exercise Minimizes Changes in Lean Leg Mass, Strength and Endurance

Decreases in muscle strength and endurance frequently are observed in non-weightbearing conditions such as bed rest (BR), spaceflight or limb immobilization. Purpose: Ow purpose was to determine if supine treadmill exercise against simulated gravity, by application of lower body negative pressure (LBNP), prevents loss of lean leg mass, strength and endurance during 30 d of 6deg head-down bed rest (BR). Methods: Fifteen pairs of monozygous twins (8 male, 7 female pairs; 26+/-4 yrs; 170+/-12 cm; 62.6+/-11.3 kg; mean+/-SD) were subjects in the present study. One sibling of each pair of twins was randomly assigned to either an exercise (EX) or non-exercise (CON) group. The EX twin walked/jogged on a vertical treadmill within LBNP chamber 6 d/wk using a 40-min interval exercise protocol at 40-80% of pre-BR VO(sub 2peak). LBNP was adjusted individually for each subject such that footward force was between 1.0 and 1.2 times body weight (-53+/-5 mmHg LBNP). The CON twin performed no exercise during BR. Subjects performed isokinetic knee (60 and 120deg/s) and ankle (60deg/s) testing to assess strength and endurance (End) before and after BR. They also had their lean leg mass (L(sub mass)) evaluated by DEXA before and after BR. Results: Changes in peak torque (T(sub pk)) were smaller for flexion (flex) than for extension (ext) after BR and did not differ between groups. The CON group had larger decreases (P<0.05) in L(sub mass), knee and ankle ext T(sub pk), and knee ext End