Greenhouse gas emission reductions from domestic anaerobic digesters linked with sustainable sanitation in rural China

Anaerobic digesters provide clean, renewable energy (biogas) by converting organic waste to methane, and are a key part of China's comprehensive rural energy plan. Here, experimental and modeling results are used to quantify the net greenhouse gas (GHG) reduction from substituting a household anaerobic digester for traditional energy sources in Sichuan, China. Tunable diode laser absorption spectroscopy and radial plume mapping were used to estimate the mass flux of fugitive methane emissions from active digesters. Using household energy budgets, the net improvement in GHG emissions associated with biogas installation was estimated using global warming commitment (GWC) as a consolidated measure of the warming effects of GHG emissions from cooking. In all scenarios biogas households had lower GWC than nonbiogas households, by as much as 54%. Even biogas households with methane leakage exhibited lower GWC than nonbiogas households, by as much as 48%. Based only on the averted GHG emissions over 10 years, the monetary value of a biogas installation was conservatively estimated at US$28.30 ($16.07 ton(-1) CO(2)-eq), which is available to partly offset construction costs. The interaction of biogas installation programs with policies supporting improved stoves, renewable harvesting of biomass, and energy interventions with substantial health cobenefits are discussed.     

Smokers are unaware of the filter vents now on most cigarettes: results of a national survey

OBJECTIVE: To evaluate awareness and knowledge of cigarette filter ventilation in a national probability sample of smokers of Ultra-light, Light, and regular cigarettes. DESIGN: Random-digit-dialling and computer-assisted telephone interviewing was used on a probability sample of daily cigarette smokers (ages 18 and above). SUBJECTS AND SETTING: 218 Smokers of Ultra-light cigarettes, 360 smokers of Light cigarettes, and 210 smokers of Regular cigarettes living in the continental United States. MAIN OUTCOME MEASURES: Percentage of respondents indicating knowledge of the presence of filter vents and the consequences of behavioural blocking of vents. RESULTS: Many smokers had not heard about or seen the filter holes: 43% (95% CI = 36 to 50%) of smokers of Ultra-lights, 39% (95% CI = 34 to 44%) of smokers of Lights, and 47% (95% CI = 40 to 54%) of smokers of Regulars. About two in three smokers either did not know of the existence of rings of small holes on the filters of some cigarettes, or did not know that blocking increases tar yields: 69% (95% CI = 63 to 75%) of Ultra- lights, 66% (95% CI = 61 to 71%) of Lights, and 69% (95% CI = 63 to 75%) of Regulars. CONCLUSIONS: Smokers are generally unaware of the presence and function of filter vents-a major design feature subject to behavioural blocking by smokers and now present on most cigarettes in the United States. Smokers and policy-makers need to be informed about the presence of filter vents and how vent blocking increases tar and nicotine yields from ostensibly very low-yield cigarettes.


     

On Nonuniform Windowing M-ary FSK Data in a DFT-Based Detector

Nonuniform amplitude windowingM-ary frequency shiftkeying (FSK) data prior to demodulation reduces the crosstalk normally caused by Doppler and oscillator drift. A major disadvantage of such nonuniform windowing is the loss in signal detectability as a result of the mismatch between the nonuniform windowed signal and the uniform windowed detectors. This paper is concerned with the tradeoff of nonuniform windowing to combat frequency offset degradation and signal detectability losses caused by the use of such windows in a DFT (discrete Fourier transform)-based detector of noncoherentM-ary FSK. What is shown here is that if a frequency control system can maintain frequency to within a certain deviation (which depends on error rate and nonuniform window), nonuniform windowing is not warranted; on the other hand, if the frequency deviation becomes too large, nonuniform windowing is advised. A technique is developed that will determine this crossover deviation.     

MALDI-linear ion trap microprobe MS/MS studies of the effects of dichloroacetate on lipid content of nerve tissue

The direct analysis of tissue from both the central and peripheral nervous systems of control rats and those administered the potential neurotoxin dichloroacetate (DCA) was investigated using an intermediate-pressure matrix-assisted laser desorption/ionization (IP-MALDI) source coupled to a linear ion trap (LIT) mass spectrometer. The matrix, 2,5-dihydroxybenzoic acid, was applied to the tissue using a novel automated inkjet printer system. The MSn capabilities of the LIT allowed identification of lipids desorbed directly from tissue. A marked decrease is observed in the intensity of lipid ions in spinal cord and sciatic nerve tissues from rats exposed to DCA. The results also demonstrate the rapid, sensitive, and semiquantitative capabilities of this method.     

Structural behavior of alkali activated fly ash concrete. Part 1: mixture design, material properties and sample fabrication

Alkali Activated Fly Ash Concrete (AAFAC) is an alternative form of concrete that uses fly ash as a 100 % replacement for ordinary portland cement. In producing AAFAC, fly ash is combined with alkali activators that chemically react to form a binder. When combined further with fine and coarse aggregates and often cured at elevated temperature, a concrete material is produced with strength and stiffness properties similar to ordinary portland cement concrete (OPCC). In this paper fabrication of full scale steel reinforced AAFAC beams is presented. The research scope includes: development of an AAFAC mixture design, fabrication of nine AAFAC beam samples, development of an elevated temperature curing system, temperature measurement during curing, and investigation of hardened AAFAC material properties. Results show AAFAC can be manufactured in the same way as OPCC, and that it has a self consolidating consistency in the fresh state. Curing at 60 °C for 24 h produced very rapid strength gain. Compression strengths at 1 day ranged between 47 and 53 MPa, with 28 days compression strengths ranging from 48 to 55 MPa. Material test results show AAFAC is a brittle material with an approximately linear stress–strain response, and an elastic modulus slightly less than that predicted by ACI 318.     

Persistence of host-associated Bacteroidales gene markers and their quantitative detection in an urban and agricultural mixed prairie watershed

Microbial source tracking is an emerging tool developed to protect water sources from faecal pollution. In this study, we evaluated the suitability of real time-quantitative PCR (qPCR) Taqman assays developed for detection of host-associated Bacteroidales markers in a prairie watershed. The qPCR primers and probes used in this study exhibited high accuracy (88-96% sensitivity and ≥99% host specificity) in detecting Bacteroidales spp. that are associated with faeces from humans, ruminants, bovines, and horses. The ruminant- and human-associated markers were also found in high concentrations within individual faecal samples, ranging from 3.4 to 7.3 log₁₀ marker copy number g⁻¹ of individual host faeces. Following validation of host sensitivity and specificity, the host-associated Bacteroidales markers were detected in the Qu’Appelle Valley watershed of Saskatchewan, Canada which experiences a diversity of anthropogenic inputs. Concentrations of the ruminant marker were well-correlated with proximity to cattle operations and there was a correlation between the marker and Escherichia coli concentrations at these sites. Low concentrations of the human faecal marker were measured throughout the sampling sites, and may indicate a consistent influx of human faecal pollution into the watershed area. Persistence of each of the Bacteroidales host-associated marker was also studied in situ. The results indicated that the markers persist for shorter periods of time (99% decay in <8 days) compared with the conventional E. coli marker (99% decay in >15 days), suggesting they are effective at detecting recent faecal contamination events. The levels of Bacteroidales markers and E. coli counts did not correlate with the presence of the pathogenic bacteria, Salmonella spp. or Campylobacter spp. detected in the Qu’Appelle Valley. Collectively, the results obtained in this study demonstrated that the qPCR approach for detecting host-associated Bacteroidales spp. markers can be a useful tool in helping to determine host-specific impacts of faecal pollution into a prairie watershed.     

Robust stability of multidimensional difference equations with shift-variant coefficients

This paper addresses the asymptotic stability of multidimensional systems represented by first hyperquadrant causal linear difference equations whose coefficients are shift-varying. The results extend previous 1-D results, and include the derivation of a fixed region of stability in the parameter space, as well as a sequence of shift-variant parameter regions. In the case of a fixed parameter region, the largest stable hyperdiamond centered at the origin will be obtained. For the shift-variant case, it will be shown that the instantaneous stable parameter region always includes this hyperdiamond.     

The Au-In-Pb system:The AuIn2-In-Pb portion

The Au-In-Pb system was investigated in the AuIn-In-Pb portion of the system. Pb-AuIn and Pb-AuIn₂ quasibinary systems were found:the first, consisting of a eutectic and a monotectic reaction and the second, a eutectic with an inflection in the liquidus. The chief source of information was differential thermal analyses and verification by metallography, X-ray diffraction and microprobe analyses. Four isothermal reactions were found as follows: 1) L₁ ? L₂ + AuIn₂ + AuIn at 433°Celsius 2) L₁ ? Pb + AuIn₂ + AuIn at 316°Celsius 3) Pb + L ? α + AuIn₂ at 172°Celsius 4) α₁ + L ? AuIn₂ + In at 159°Celsius. Verification of these events and the isopleth from 50-50 wt pct Pb-In, a typical solder, to ≈ 47 wt pct Au are given.     

On the Definition of Microhardness

Microhardness testing can be a very useful tool for studying modern materials, but is plagued by well-known experimental difficulties. Reasons for the unusual behavior of hardness data at very low loads are explored by Monte Carlo simulation. These simulations bear remarkable resemblance to the results of actual hardness experiments. The limit of hardness as load or indentation depth tends to zero is shown to depend on experimental error rather than upon intrinsic material properties. The large scatter of hardness data at very low loads is insured by the accepted definition of hardness. A new definition of hardness is suggested which eliminates much of this scatter and possesses a limit as indentation depth approaches zero. Some simple calculations are used to show the utility of this new approach to hardness testing.