Regional contingencies in the relationship between aboveground biomass and litter in the world’s grasslands

Based on regional-scale studies, aboveground production and litter decomposition are thought to positively covary, because they are driven by shared biotic and climatic factors. Until now we have been unable to test whether production and decomposition are generally coupled across climatically dissimilar regions, because we lacked replicated data collected within a single vegetation type across multiple regions, obfuscating the drivers and generality of the association between production and decomposition. Furthermore, our understanding of the relationships between production and decomposition rests heavily on separate meta-analyses of each response, because no studies have simultaneously measured production and the accumulation or decomposition of litter using consistent methods at globally relevant scales. Here, we use a multi-country grassland dataset collected using a standardized protocol to show that live plant biomass (an estimate of aboveground net primary production) and litter disappearance (represented by mass loss of aboveground litter) do not strongly covary. Live biomass and litter disappearance varied at different spatial scales. There was substantial variation in live biomass among continents, sites and plots whereas among continent differences accounted for most of the variation in litter disappearance rates. Although there were strong associations among aboveground biomass, litter disappearance and climatic factors in some regions (e.g. U.S. Great Plains), these relationships were inconsistent within and among the regions represented by this study. These results highlight the importance of replication among regions and continents when characterizing the correlations between ecosystem processes and interpreting their global-scale implications for carbon flux. We must exercise caution in parameterizing litter decomposition and aboveground production in future regional and global carbon models as their relationship is complex.

Infrared and Raman spectroscopic characterization of the silicate mineral olmiite CaMn2+[SiO3(OH)](OH) : implications for the molecular structure

We have studied the mineral olmiite CaMn\[SiO3(OH)](OH) which forms a series with its calcium analogue poldevaartite CaCa\[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis , Raman and infrared spectroscopy. Chemical analysis shows the mineral is pure and contains only calcium and manganese in the formula. Thermogravimetric analysis proves the mineral decomposes at 502°C with a mass loss of 8.8% compared with the theoretical mass loss of 8.737%. A strong Raman band at 853 cm-1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm-1 are attributed to the antisymmetric vibrations.Two intense Raman bands observed at 3511 and 3550 cm-1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of olmiite.

Influence of kaolinite/carbon black hybridization on combustion and thermal decomposition behaviors of NR composites

A series of NR composites filled with modified kaolinite (MK), carbon black (CB) and the hybrid fillercontained MK and CB, were prepared by melt blending. The microstructure, combustion and thermaldecomposition behaviors of NR composites were characterized by TEM, XRD, infrared spectroscopy, conecalorimeter test (CCT) and thermal-gravimetric analysis (TG). The results show that the filler hybridizationcan improve the dispensability and shape of the kaolinite sheets in the rubber matrix and change theinterface bond between kaolinite particles and rubber molecules. NR-3 filled by 10 phr MK and 40 phr CBhas the lowest heat release rate (HRR), mass loss rate (MLR), total heat release (THR), smoke productionrate (SPR) and the highest char residue among all the NR composites. Therefore, the hybridization ofthe carbon black particles with the kaolinite particles can effectively improve the thermal stability andcombustion properties of NR composites.

Computer simulation of scaffold degradation

Scaffolds are porous biocompatible materials with suitable microarchitectures that are designed to allow for cell adhesion, growth and proliferation. They are used in combination with cells in regenerative medicine to promote tissue regeneration by means of a controlled deposition of natural extracellular matrix by the hosted cells therein. This healing process is in many cases accompanied by scaffold degradation up to its total disappearance when the scaffold is made of a biodegradable material. This work presents a computational model that simulates the degradation of scaffolds. The model works with three-dimensional microstructures, which have been previously discretised into small cubic homogeneous elements, called voxels. The model simulates the evolution of the degradation of the scaffold using a Monte Carlo algorithm, which takes into account the curvature of the surface of the fibres. The simulation results obtained in this study are in good agreement with empirical degradation measurements performed by mass loss on scaffolds after exposure to an etching alkaline solution.

Insight into the thermal decomposition of kaolinite intercalated with potassium acetate : an evolved gas analysis

The thermal decomposition process of kaolinite–potassium acetate intercalation complex has been studied using simultaneous thermogravimetry coupled with Fourier-transform infrared spectroscopy and mass spectrometry (TG-FTIR-MS). The results showed that the thermal decomposition of the complex took place in four temperature ranges, namely 50–100, 260–320, 320–550, and 650–780 °C. The maximal mass losses rate for the thermal decomposition of the kaolinite–potassium acetate intercalation complex was observed at 81, 296, 378, 411, 486, and 733 °C, which was attributed to (a) loss of the adsorbed water, (b) thermal decomposition of surface-adsorbed potassium acetate (KAc), (c) the loss of the water coordinated to potassium acetate in the intercalated kaolinite, (d) the thermal decomposition of intercalated KAc in the interlayer of kaolinite and the removal of inner surface hydroxyls, (e) the loss of the inner hydroxyls, and (f) the thermal decomposition of carbonate derived from the decomposition of KAc. The thermal decomposition of intercalated potassium acetate started in the range 320–550 °C accompanied by the release of water, acetone, carbon dioxide, and acetic acid. The identification of pyrolysis fragment ions provided insight into the thermal decomposition mechanism. The results showed that the main decomposition fragment ions of the kaolinite–KAc intercalation complex were water, acetone, carbon dioxide, and acetic acid. TG-FTIR-MS was demonstrated to be a powerful tool for the investigation of kaolinite intercalation complexes. It delivers a detailed insight into the thermal decomposition processes of the kaolinite intercalation complexes characterized by mass loss and the evolved gases.

The effects of metabolic work rate and ambient environment on physiological tolerance times while wearing explosive and chemical personal protective equipment

This study evaluated the physiological tolerance times when wearing explosive and chemical (>35kg) personal protective equipment (PPE) in simulated environmental extremes across a range of differing work intensities. Twelve healthy males undertook nine trials which involved walking on a treadmill at 2.5, 4 and 5.5 km.h-1 in the following environmental conditions, 21, 30 and 37 °C wet bulb globe temperature (WBGT). Participants exercised for 60 min or until volitional fatigue, core temperature reached 39 °C, or heart rate exceeded 90% of maximum. Tolerance time, core temperature, skin temperature, mean body temperature, heart rate and body mass loss were measured. Exercise time was reduced in the higher WBGT environments (WBGT37

Characterization of the sulphate mineral coquimbite, a secondary iron sulphate from Javier Ortega mine, Lucanas Province, Peru – Using infrared, Raman spectroscopy and thermogravimetry

The mineral coquimbite has been analysed using a range of techniques including SEM with EDX, thermal analytical techniques and Raman and infrared spectroscopy. The mineral originated from the Javier Ortega mine, Lucanas Province, Peru. The chemical formula was determined as ðFe3þ 1:37; Al0:63ÞP2:00ðSO4Þ3 9H2O. Thermal analysis showed a total mass loss of 73.4% on heating to 1000 C. A mass loss of 30.43% at 641.4 C is attributed to the loss of SO3. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of sulphate tetrahedra, aluminium oxide/hydroxide octahedra, water molecules and hydroxyl ions. The Raman spectrum shows well resolved bands at 2994, 3176, 3327, 3422 and 3580 cm 1 attributed to water stretching vibrations. Vibrational spectroscopy combined with thermal analysis provides insight into the structure of coquimbite.

Silylation of mechanically ground kaolinite

Silylated kaolinites were synthesized at 80°C without the use of inert gas protection. The method presented started with mechanical grinding of kaolinite, followed by grafting with 3-aminopropyltriethoxysilane (APTES). The mechanical grinding treatment destroyed the ordered sheets of kaolinite, formed fine fragments and generated broken bonds (undercoordinated metal ions). These broken bonds served as new sites for the condensation with APTES. Fourier transform infrared spectroscopy (FTIR) confirmed the existence of –CH2 from APTES. 29Si cross-polarization magic-angle spinning nuclear magnetic resonance spectroscopy (29Si CP/MAS NMR) showed that the principal bonding mechanism between APTES and kaolinite fitted a tridentate silylation model (T3) with a chemical shift at 66.7 ppm. The silane loadings of the silylated samples were estimated from the mass loss obtained by TG-DTG curves. The results showed that the 6-hour ground kaolinite could be grafted with the most APTES (7.0%) using cyclohexane as solvent. The loaded amount of APTES in the silylated samples obtained in different solvents decreased in the order as: nonpolar solvent > polar solvent with low dielectric constant (toluene) > polar solvent with high dielectric constant (ethanol).

Vibrational spectroscopic study of poldervaartite CaCa[SiO3(OH)(OH)]

We have studied the mineral poldervaartite CaCa\[SiO3(OH)(OH)] which forms a series with its manganese analogue olmiite CaMn\[SiO3(OH)](OH) using a range of techniques including scanning electron microscopy, thermogravimetric analysis, Raman and infrared spectroscopy. Chemical analysis shows the mineral is reasonably pure and contains only calcium and manganese with low amounts of Al and F. Thermogravimetric analysis proves the mineral decomposes at 485 °C with a mass loss of 7.6% compared with the theoretical mass loss of 7.7%. A strong Raman band at 852 cm−1 is assigned to the SiO stretching vibration of the SiO3(OH) units. Two Raman bands at 914 and 953 cm−1 are attributed to the antisymmetric vibrations. Intense prominent peaks observed at 3487, 3502, 3509, 3521 and 3547 cm−1 are assigned to the OH stretching vibration of the SiO3(OH) units. The observation of multiple OH bands supports the concept of the non-equivalence of the OH units. Vibrational spectroscopy enables a detailed assessment of the molecular structure of poldervaartite.

Thermogravimetric analysis of tetradecyltrimethylammonium bromide-modified beidellites

The surfaces of natural beidellite clay were modified with cationic surfactant, tetradecyltrimethylammonium bromide, at different concentrations. The organo-beidellites were analysed using thermogravimetric analysis which shows four thermal oxidation/decomposition steps. The first step of mass loss is observed from room temperature to 130 °C due to the dehydration of adsorbed water. The second step of mass loss between 130 and 400 °C is attributed to the oxidation step of the intercalated organic surfactant with the formation of charcoal. The third mass loss happens between 400 and 500 °C which is assigned to the loss of hydroxyl groups on the edge of clays and the further oxidation step of charcoal. The fourth step is ascribed to the loss of structural OH units as well as the final oxidation/decomposition step of charcoal which takes place between 500 and 700 °C. Thermogravimetric analysis has proven to be a useful tool for estimating loaded surfactant amount.

Borate protection of softwood from Coptotermes acinaciformis (Isoptera: Rhinotermitidae) damage: Variation in protection thresholds explained

Laboratory and field data reported in the literature are confusing with regard to “adequate” protection thresholds for borate timber preservatives. The confusion is compounded by differences in termite species, timber species and test methodology. Laboratory data indicate a borate retention of 0.5% mass/mass (m/m) boric acid equivalent (BAE) would cause >90% termite mortality and restrict mass loss in test specimens to ≤5%. Field data generally suggest that borate retentions appreciably >0.5% m/m BAE are required. We report two field experiments with varying amounts of untreated feeder material in which Coptotermes acinaciformis (Froggatt) (Isoptera: Rhinotermitidae) responses to borate-treated radiata (Monterey) pine, Pinus radiata D. Don, were measured. The apparently conflicting results between laboratory and field data are explained by the presence or absence of untreated feeder material in the test environment. In the absence of untreated feeder material, wood containing 0.5% BAE provided adequate protection from Coptotermes sp., whereas in the presence of untreated feeder material, increased retentions were required. Furthermore, the retentions required increased with increased amounts of susceptible material present. Some termites, Nasutitermes sp. and Mastotermes darwiniensis Froggatt, for example, are borate-tolerant and borate timber preservatives are not a viable management option with these species. The lack of uniform standards for termite test methodology and assessment criteria for efficacy across the world is recognized as a difficulty with research into the performance of timber preservatives with termites. The many variables in laboratory and field assays make “prescriptive” standards difficult to recommend. The use of “performance” standards to define efficacy criteria (“adequate” protection) is discussed.

Improved termite resistance of wood by wax impregnation.

We investigated the effect of wax-treated and biocide-free wood specimens against three different termite species. A laboratory no-choice test with Reticulitermes banyulensis Clément was carried out in Valencia (Spain) under Mediterranean conditions for eight weeks. Scots pine sapwood (Pinus sylvestris L.) fully impregnated with distinct waxes was used. Two field trials were conducted with Coptotermes acinaciformis (Froggatt) and Mastotermes darwiniensis Froggatt in northern Queensland (Australia) with wax-impregnated beech (Fagus sylvatica L.) for 16 weeks. All three subterranean termites are of major economic importance in their respective regions. The results indicated that feeding pressure by the termites was sufficient within all trials for a valid test. Wax-impregnated Scots pine sapwood was classified as durable. No termites survived the test. The results showed an aging process under submersion conditions, which lead to a classification of moderately durable. The paraffin treatment showed good termite resistance under both test procedures, and was classified as durable. The Australian field trials showed a decreased mass loss of wax-treated beech, in which an amide wax showed excellent termite resistance. The results indicate a clear dependence of the termite resistance on the type and ratio of wax used and the feeding preferences of the specific termite species.

Lot feeding and intensive livestock manure and effluent management

Manure management emissions may present much greater opportunity for greenhouse gas mitigation in the feedlot, pig, chicken meat, egg and diary industries, than the current IPCC and DCC calculation guidelines suggest. Current literature and understanding of manure mass loss throughout the manure management system does not support these current guidelines; in which the emission rates are fixed and consequently don't allow incentives for reduced emissions.

From spent Mg/Al layered double hydroxide to porous carbon materials

Adsorption has been considered as an efficient method for the treatment of dye effluents, but properdisposal of the spent adsorbents is still a challenge. This work attempts to provide a facile methodto reutilize the spent Mg/Al layered double hydroxide (Mg/Al-LDH) after the adsorption of orange II(OII). Herein, the spent hybrid was carbonized under the protection of nitrogen, and then washedwith acid to obtain porous carbon materials. Thermogravimetric analysis results suggested that thecarbonization could be well achieved above 600◦C, as mass loss of the spent hybrid gradually stabilized. Therefore, the carbonization process was carried out at 600, 800, and 1000 ◦C, respectively. Scanning electron microscope showed that the obtained carbon materials possessed a crooked flaky morphology. Nitrogen adsorption–desorption results showed that the carbon materials had large BET surface area and pore volume, e.g., 1426 m2/g and 1.67 cm3/g for the sample carbonized at 800 ◦C. Moreover, the pore structure and surface chemistry compositions were tunable, as they were sensitive to the temperature. Toluene adsorption results demonstrated that the carbon materials had high efficiency in toluene removal. This work provided a facile approach for synthesizing porous carbon materials using spent Mg/Al-LDH.

A boat hitchhiker's guide to survival: Cabomba caroliniana desiccation resistance and survival ability

Cabomba caroliniana is a submersed macrophyte that has become a serious invader. Cabomba predominantly spreads by stem fragments, in particular through unintentional transport on boat trailers ('hitch hiking'). Desiccation resistance affects the potential dispersal radius. Therefore, knowledge of maximum survival times allows predicting future dispersal. Experiments were conducted to assess desiccation resistance and survival ability of cabomba fragments under various environmental scenarios. Cabomba fragments were highly tolerant of desiccation. However, even relatively low wind speeds resulted in rapid mass loss, indicating a low survival rate of fragments exposed to air currents, such as fragments transported on a boat trailer. The experiments indicated that cabomba could survive at least 3 h of overland transport if exposed to wind. However, even small clumps of cabomba could potentially survive up to 42 h. Thus, targeting the transport of clumps of macrophytes should receive high priority in management. The high resilience of cabomba to desiccation demonstrates the risk of continuing spread. Because of the high probability of fragment viability on arrival, preventing fragment uptake on boat trailers is paramount to reduce the risk of further spread. These findings will assist improving models that predict the spread of aquatic invasive macrophytes.