Two-stage anaerobic digestion enables heavy metal removal.

To fully exploit the environmental benefits of the biogas process, the digestate should be recycled as biofertiliser to agriculture. This practice can however be jeopardized by the presence of unwanted compounds such as heavy metals in the digestate. By using two-stage digestion, where the first stage includes hydrolysis/acidification and liquefaction of the substrate, heavy metals can be transferred to the leachate. From the leachate, metals can then be removed by adsorption. In this study, up to 70% of the Ni, 40% of the Zn and 25% of the Cd present in maize was removed when the leachate from hydrolysis was circulated over a macroporous polyacrylamide column for 6 days. For Cu and Pb, the mobilization in the hydrolytic stage was lower which resulted in a low removal. A more efficient two-stage process with improved substrate hydrolysis would give lower pH and/or longer periods with low pH in the hydrolytic stage. This is likely to increase metal mobilisation, and would open up for an excellent opportunity of heavy metal removal.     

Between Elderly Parents and Grandchildren—Geographic Proximity and Trends in Four-Generation Families

In an ageing society, families may have an important role in the caretaking and well-being of the elderly. Demographic changes have an impact on the size and structure of families; one aspect is how intergenerational support is distributed when there is a need for support to both older and younger generations at the same time. Another vital aspect of the provision of care for the elderly is geographic proximity. This study is oriented towards the potential “both-end carers” i.e. persons who have grandchildren in potential need of care while still having living ageing parents. The incidence of having grandchildren and having living parents at age 55 and the proximity between generations is described using Swedish register data. The results show that the share of 55-year-olds who are grandparents decreased dramatically from 70% to 35% between 1990 and 2005. As expected, more 55-year-olds have living parents—a proportion that increased from 37% to 47% during this period. As a result of delayed childbearing among the children of these cohorts, the likelihood of belonging to a four-generation family among 55-year-olds has not increased, despite increased longevity. Furthermore, most individuals live within daily reach of their kin and no evidence was found of a trend of increasing geographic distances between generations.     

Effect of particle size on biogas yield from sisal fibre waste

The degradation and biogas production potential of sisal fibre waste could be significantly increased by pre-treatment for reduction of particle size. Batch-wise anaerobic digestion of sisal fibre waste was carried out in 1-l digesters with fibre sizes ranging from 2 to 100 mm, at an ambient temperature of 33 °C. Sediment from a stabilisation pond at a sisal production plant was used as starter seed. Total fibre degradation increased from 31% to 70% for the 2 mm fibres, compared to untreated sisal fibres. Furthermore, the results confirmed that methane yield was inversely proportional to particle size. Methane yield increased by 23% when the fibres were cut to 2 mm size and was 0.22 m³ CH₄/kg volatile solids, compared to 0.18 m³ CH₄/kg volatile solids for untreated fibres. By anaerobic digestion and biogas production, the 148,000 tonne of waste sisal fibres generated annually in Tanzania could yield 22 million m³ of methane, and an additional 5 million m³ of methane if pre-treatment by size reduction to 2 mm was applied.     

Advanced process monitoring—a major step towards adaptive control

Adaptive Control (AC) of machine tools requires many kinds of measured input data. The more information about the complex metal cutting process that can be obtained, the better the process can be controlled.

The paper describes an Adaptive Control Optimization (ACO) system for turning operations. The system continuously chooses Optimal Cutting Data (OCD), taking into account both economical criteria and technical limitations.

The system operates at three different levels:

• • Advanced Process Monitoring

• • Adaptive Control Constraint (ACC)

• • Adaptive Control Optimization (ACO).

Two commercial monitoring systems perform process monitoring. In addition, five independent measurement systems have been developed.

A dedicated vision system has been installed in the lathe to measure the tool flank wear between cuts. The flank wear data are utilized to predict the tool life. Based upon these predictions economical optimum cutting data can be calculated at the ACO level.

To obtain in-process real-time control of the metal cutting process the cutting forces are measured during machining. The forces are measured with conventional piezoelectric force transducers which are located between the turret housing and the cross-slide. The measured force signals are processed by a dedicated microcontroller at the ACC level and cutting data adjustments are fed back to the machine control.

A vibration measurement system, which either can be connected to an accelerometer or use the dynamic force signal from the piezoelectric force transducer, is part of a vibration control module at the ACC level. An ultra-fast signal processor performs the signal analysis.

The remaining two measurement systems—a high frequency tool signal analysis system and a power spectra analysis system—are mentioned in the paper but not further discussed.

Finally, the paper deals with how the strategies at the three different levels will be combined, in order to form an AC system. The monitoring tasks will always reside in the background and be activated if any failure occurs. The ACO subsystem will act as a path-finder and suggest cutting data. The active control tasks will, however, be carried out at the ACC level.     

Measurement of urinary monohydroxy polycyclic aromatic hydrocarbons using automated liquid-liquid extraction and gas chromatography/isotope dilution high-resolution mass spectrometry

A method for the measurement of 24 hydroxylated polycyclic aromatic hydrocarbon metabolites (OH-PAHs) in urine has been developed. The method is based on enzymatic deconjugation, automated liquid-liquid extraction, and gas chromatography/isotope dilution high-resolution mass spectrometry after derivatization of the OH-PAHs to the trimethylsilylated derivatives. The metabolites included in the current method are formed from eight different parent compounds. The limits of detection were below 7 pg/mL when using a sample size of 2 mL of urine, except for 1- and 2-naphthols (18 and 12 pg/mL, respectively). The enzymatic deconjugation efficiency, verified by deconjugation of urine samples spiked with alpha-naphthyl beta-d-glucuronide sodium salt (1-NAP-GLU) and pyrene-1-sulfate potassium salt (1-PYR-SULF), was determined to be 97% for 1-NAP-GLU conjugate and 84% for 1-PYR-SULF. The overall coefficients of variance for six batches of quality control samples (n = 42), was 2.9-11%. Mean method recoveries of the 13C-labeled internal standards were 66-72%, except for 13C6-1-naphthol (46%). The throughput of this method has been determined to be 40 samples per day per analyst. This method is currently applied to epidemiological studies, such as the National Exposure and Nutrition Examination Survey (NHANES), to measure human exposure to PAHs.     

Inhibition of Bacterial and Filamentous Fungal Growth in High Moisture,Nonsterile Corn with Intermittent Pumping of Trans‐2‐Hexenal Vapor

Trans‐2‐hexenal (T2H), a plant‐produced aldehyde, was intermittently pumped over a 7 d period into a small, bench top model of stored corn (nonsterile, moisture content about 23%). Naturally occurring bacteria and fungi, including added Aspergillus flavus, grew rapidly on corn not treated with T2H vapor. However, intermittently pumped T2H (30 min per 2 h or 30 min per 12 h) significantly reduced bacterial and fungal viable populations, with nearly 100% fungal viability loss observed after either (1) one day of pumping at the 30 min per 2 h rate or (2) pumping cycles of 30 min per 12 h period over the initial 48 to 72 h of incubation. Data suggest that short‐term intermittent fumigation of stored corn with T2H could prevent growth of bacteria and mycotoxigenic fungi such as A. flavus.     

Steam pretreatment of dry and ensiled industrial hemp for ethanol production

Biomass can be converted into liquid and gaseous biofuels with good efficiency. In this study, the conversion of industrial hemp (Cannabis sativa L.), a biomass source that can be cultivated with a high biomass yield per hectare, was used. Steam pretreatment of dry and ensiled hemp was investigated prior to ethanol production. The pretreatment efficiency was evaluated in terms of sugar recovery and polysaccharide conversion in the enzymatic hydrolysis step. For both materials, impregnation with 2% SO₂ followed by steam pretreatment at 210 °C for 5 min were found to be the optimal conditions leading to the highest overall yield of glucose. Simultaneous saccharification and fermentation experiments carried out with optimised pretreatment conditions resulted in ethanol yields of 163 g kg^?1 ensiled hemp (dry matter) (71% of the theoretical maximum) and 171 g kg^?1 dry hemp (74%), which corresponds to 206–216 l Mg^?1 ethanol based on initial dry material.     

Enhancement of anaerobic batch digestion of sisal pulp waste by mesophilic aerobic pre-treatment

Pre-treatment of sisal pulp prior to its anaerobic digestion was investigated using an activated sludge mixed culture under aerobic conditions in batch bioreactors at 37 degrees C. The progression of aerobic pre-treatment of the residue in relation to the activities of some extracellular hydrolytic enzymes in the slurry was monitored. The highest activity of hydrolytic enzymes was obtained at 9 h of pre-treatment. Filter paper cellulase had a maximum activity of 0.90 IU/ml, while carboxymethyl cellulase, amylase and xylanase were produced to a maximum of about 0.40 IU/ml. The methane yield obtained after anaerobic digestion of the pre-treated pulp ranged between 0.12 and 0.24 m3 CH4/kg VS added. The highest and lowest values were obtained for 9 and 72 h of pre-treatment, respectively. Nine hours of pre-treatment of sisal pulp prior to anaerobic digestion demonstrated a 26% higher methane yield when compared to the sisal pulp without pre-treatment. The consortia of microorganisms in activated sludge demonstrated a useful potential in the production of hydrolases acting on major macromolecules of sisal pulp. The fact that a correlation was observed between high enzyme activity and high methane yield at 9 h of aerobic pre-treatment suggests that such a short pre-treatment period could be an alternative option for increasing solubilization of sisal pulp and promoting methane productivity.     

The role of the growth hormone/insulin-like growth factor I axis in stimulation of protein synthesis in skeletal muscles following oral refeeding

The mechanisms behind stimulation of protein synthesis in skeletal muscles following oral feeding are not well understood. Previous research has not confirmed that insulin is a major factor behind this stimulation. In the present study we have used genetically altered mice, with either a lack of GH secretion due to a mutational gene inactivation [GH (-/-) dwarf, DW/JOrlBom-dw] or mice with a homozygous site-specific insertion mutation in the insulin-like growth factor-1 gene [IGF-I (m/m)], leading to a deficient IGF-I production. These gene knock-outs were used in comparison to their normal wild types for evaluation of the role that the GH/IGF-I axis may have in activation of nutritionally induced stimulation of protein synthesis in skeletal muscles during oral refeeding. Weight stable adult C57B16 mice served as an additional normal control group. Protein synthesis was measured by a modified flooding dose technique with radioactive L-[14C-U]phenylalanine incorporation into acid precipitated muscle proteins. Fractional protein synthesis in skeletal muscles after an overnight fast was comparable among C57B16 (0.076 +/- 0.009%/h), wild-type IGF-I(+/+) (0.061 +/- 0.008) and IGF-I(m/m) deficient mice (0.068 +/- 0.006%/h), whereas GH(-/-) incompetent mice had a lower fractional synthesis rate compared with GH(+/+) competent mice (0.045 +/- 0.006 vs. 0.068 +/- 0.007, P < 0.05). Refeeding with standard chow diet stimulated protein synthesis in muscles by more than 60% in all animal groups. This response was independent of circulating GH, total IGF-I concentrations in blood, as well as up-regulation of locally produced IGF-I messenger RNA (mRNA) in skeletal muscles.