Effects of mineral admixtures and lime on disintegration of alkali-activated slag exposed to 50 °c

Alkali-activated slag can totally disintegrate when exposed to 50 C. This paper presents a study of possible solutions to avoid this disintegration by using silica fume (SF) and fly ash (FA) to partially replaceslag. It was found that partial replacement of slag with SF significantly reduces strength loss. A mixture of 50% slag 50% SF (cured at 25 and 60 C) showed no strength loss after the exposure. In comparison, a55% drop of strength was observed in a mixture of 50% slag 50% FA (cured at 25 C) after the same exposure.However, the strength loss of this mixture was reduced by 50% when cured at 60 C. The presence oflime in AAS pastes increases the degree of strength loss after the exposure. The mechanisms for the abovestrength results are discussed in terms of hydration products and microcracking.

Bipolar missed states : the diagnosis and clinical salience of bipolar mixed states

Objective: To explore diagnostic and treatment issues concerning bipolar mixed states.

Method: Bipolar mixed states are described and concerns about diagnostic and treatment difficulties are summarized and discussed.

Result: Mixed states can present with equal admixtures of depressive or manic symptoms, or more commonly one component predominates. There is fair consensus, although little data, regarding the management of manic mixed states. However depressive mixed states are far more complex both in terms of recognition and management. People suffering from mixed states characteristically present with complaints of depression.

Conclusions: The boundaries between depressive mixed states and agitated depression are vague, yet carry substantial therapeutic implications. Bipolar mixed states are often difficult to treat, and tend to take much longer to settle than either pure mania or depression.  Furthermore there is data that treatment with antidepressants can worsen the course of mixed states. Hence missed diagnoses can potentially have negative clinical implications.  Therefore in this paper the clinical presentation, diagnosis and therapy of mixed states is reviewed with a view to improving management.

The allometric relationship between mean fibre diameter of mohair and the fleece-free liveweight of Angora goats over their lifetime

As mean fibre diameter (MFD) is the primary determinant of mohair price we aimed to quantify the lifetime changes in mohair MFDas Angora goats aged and grew. Measurements were made over 12 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins including South African, Texan and interbred admixtures of these and Australian sources. Records of sire, dam, birthweight, birth parity, liveweight, fleece growth and fleece quality were taken for does and castrated males (wethers) (n = 267 animals). Fleece-free liveweights (FFL_wt) were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. A restricted maximum likelihood growth curve model was developed for relating MFD to FFL_wt, age and other measurements.Asimple way of describing the results is:MFD= k (FFL_wt)b E; where k is a parameter that can vary in a systematic way with shearing(age), breed, weaning weight, sire, dam and individual; b is a parameter that is the same for nearly the whole study; and E are independent errors from a log-normal distribution. The analysis shows that ^b = 0.34, with s.e. (^b) = 0.021. Thus, mohair MFD was allometrically related to the cube root of FFLwt over the lifetime of Angora goats. However, the allometric proportionality constant differed in a systematic way with age at shearing, genetic strain, weaning weight, sire, dam and individual. For Texan-breed goats, MFD decreased as weaning weight increased (P = 0.00016). The findings indicate that management factors that affect liveweight and weaning weight have lifetime effects on mohair fibre diameter and therefore the value of mohair and the profitability of the mohair enterprise.

The allometric relationship between clean mohair growth and the fleece-free liveweight of Angora goats is affected by liveweight change

Clean fleece weight (CFWt) is affected by liveweight and change in liveweight in Merino sheep, Angora and cashmere goats. However, how these relationships progress as animals age has not been elucidated. Measurements were made over 12 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins including South African, Texan and interbred admixtures of these and Australian sources. Records of breed, sire, dam, date of birth, dam age, birthweight, birth parity, weaning weight, liveweight, fleece growth and fleece quality were taken for does and castrated males (wethers) (n = 267 animals). Fleece-free liveweights (FFLwt) were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. The average of the FFLwt at the start of the period and the FFLWt at the end of the period was calculated (AvFFLwt). Liveweight change (LwtCh) was the change in FFLwt over the period between shearings. A restricted maximum likelihood model was developed for CFWt, after log10 transformation, which allowed the observations of the same animal at different ages to be correlated in an unstructured manner. A simple way of describing the results is: CFWt = κ (AvFFLwt)β, where κ is a parameter that can vary in a systematic way with shearing age, shearing treatment and LwtCh; and β is an allometric coefficient that only varies with LwtCh. CFWt was proportional to FFLwt0.67 but only when liveweight was lost at the rate of 5–10 kg during a shearing interval of 6 months. The allometric coefficient declined to 0.3 as LwtCh increased from 10 kg loss to 20 kg gain during a shearing interval. A consequence is that, within an age group of Angora goats, the largest animals will be the least efficient in converting improved nutrition to mohair.

The relationship between the incidence of medullated fibres in mohair and live weight over the lifetime of Angora goats

The presence of even a small amount of medullated fibre, in otherwise high quality mohair, may have a pronounced adverse effect on its value and end-use potential. However, there is considerable confusion about the effects, if any, of environmental variables and management upon the incidence of medullated fibres in mohair. This study examined how the incidence of medullated fibres (Med, % by number) is related to the fleece-free live weight (FFLwt) of Angora goats of different genetic origins over their lifetime, and how the relationship varies with other lifetime factors. Measurements were made over 11 shearing periods of 6 months, on a population of Angora goats representing the current range and diversity of genetic origins in Australia, including South African, Texan and interbred admixtures of these and Australian sources. Records of breed, sire, dam, date of birth, dam age, birth weight, birth parity, weaning weight, live weight, fleece growth and fleece quality were taken for castrated males (wethers) (n = 94 animals). A restricted maximum likelihood (REML) model was developed for log10(Med + 1), which allowed the observations of the same animal at different ages to be correlated in an unstructured manner. Med varied between 0.1% and 4.3%. The median average FFLwt during a shearing interval increased from 15 kg at 1 year old to 59 kg at 6 years old. Generally, within each shearing interval, Med increased with increasing average FFLwt. However, the size and shape of the relationship differed greatly between shearing ages. For example, at 3.5 years of age Med increased from about 1.1% at an average FFLwt of 26 kg to 2.6% at 50 kg, whilst at 5.0 years of age Med only changed from 1.4% at 32 kg to 1.6% at 56 kg. Goats with mixed genetic parentage showed an increase in Med at some shearings, particularly at younger ages. Variation in animal nutrition, as measured by live weight change during shearing periods, did not affect Med. The results supplement our earlier findings that mohair mean fibre diameter and clean mohair fleece weight, but not staple length, are greater in larger Angora goats. Live weight needs to be taken into account in genetic evaluation of the incidence of medullated fibres. We conclude that any advantage in handling fewer but larger Angora goats rather than more but smaller goats will come at the detriment of producing lower quality mohair, both in terms of increased Med and mean fibre diameter.

Variation in mohair staple length over the lifetime of Angora goats

Previous work has shown that, within an Angora goat flock, clean fleece weight is proportional to fleece-free liveweight (FFLwt)2/3 and for goats of the same age and cohort, the mean mohair fibre diameter is proportional to FFLwt1/3. This indicates that fibre length might not be related to the size of animals. This study examines how mohair staple length (SL) is related to FFLwt of Angora goats of different genetic origins over their lifetime and how the relationship varies with other lifetime factors. Measurements were made over 11 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins in Australia, including South African, Texan and interbred admixtures of these and Australian sources. Records of breed, sire, dam, date of birth, dam age, birthweight, birth parity, weaning weight, liveweight, fleece growth and fleece quality were taken for castrated males (wethers) (n = 94 animals). FFLwt were determined for each goat at shearing time by subtracting the greasy fleece weight from the liveweight recorded immediately before shearing. The average of the FFLwt at the start of the period and the FFLWt at the end of the period was calculated. Liveweight change (LwtCh) was the change in FFLwt over the period between shearings. A restricted maximum likelihood model was developed for SL, which allowed the observations of the same animal at different ages to be correlated in an unstructured manner. Average SL differed from ~12.0 to ~14.5 cm, depending on age. There were no consistent effects of season. At any age, an increase of 10 kg LwtCh between animals results in about a 0.34 (s.e. = 0.087) cm increase in SL. There was no evidence of an effect of FFLwt on SL. The results confirm our hypothesis that within a single age cohort of Angora goats, there is very little, if any, relationship between the liveweight and SL of individual animals. This implies that the biological determinants of size of fibres related to cross-sectional area are substantially different to the size determinants of fibre length.

The relationship of the incidence of medullated fibres to the dimensional properties of mohair over the lifetime of Angora goats

In a range of animals, increasing mean fibre diameter (MFD) of fibre is associated with an increasing incidence of medullated fibres (Med). It would thus be expected that Med in mohair fleeces, from animals in a flock, would be related to the MFD of those fleeces. MFD of mohair is not the only dimensional attribute of fibres. Med in mohair is phenotypically and genetically related to the size of animals. This study examined how Med is related to dimensional properties of mohair over the lifetime of Angora goats and how the relationship varies with other lifetime factors. The relationship found is then examined to determine the extent that the relationship can be explained by variations in animal size of the goats. Measurements were made over 11 shearing periods on a population of Angora goats representing the current range and diversity of genetic origins in Australia, including South African, Texan and interbred admixtures of these and Australian sources. Records of breed, sire, dam, date of birth, dam age, birth weight, birth parity, weaning weight, live weight, fleece growth and fleece attributes were taken for castrated males (wethers). Animals’ fleece-free live weight (FFLwt, kg) were determined for each goat at shearing time by subtracting the greasy fleece weight from the live weight recorded immediately prior to shearing. The average of the FFLwt at the start of the period and the FFLwt at the end of the period was calculated. Two restricted maximum likelihood (REML) models were developed to relate Med to MFD, staple length (SL) and other lifetime factors. One model allowed FFLwt in the model and the other excluded FFLwt. With the exception of the 1.5 years shearing, Med strongly increased with increasing MFD whether or not adjustments were made for FFLwt measurements. In particular Med increased by 2.0% for each 1 μm increase in MFD, with no adjustment for FFLwt measurements, and increased by 1.5% for each 1 μm increase in MFD, with adjustment for FFLwt measurements. Within each shearing interval increasing average FFLwt was associated with increasing incidence of Med in a similar way to that which has been previously reported without including MFD in the model. There was no evidence that SL needed to be included in the models for Med. Mohair grown by the goats of Mixed genetic background grew mohair which had a higher incidence of Med at ages 2 and 2.5 years and the trend was apparent in other shearing periods. We can conclude that there is both a large response of Med to live weight and a large response to MFD, and that these responses are largely functionally separate. While the response to MFD is in accord with earlier work, there is an unrelated and unreported physiological mechanism that favours the production of Med in larger Angora goats. Clearly, larger Angora goats are biologically different compared with smaller animals from the same flock, in ways that are not purely related to the allometrics of size.

The value of visual fleece assessment in addition to objective measurements in identifying Angora goats of greater clean mohair production

Visual assessment of the fleece of Merino sheep is an accepted method to aid genetic improvement but there is little evidence to support the use of visual assessment for improving mohair production. This paper examines the extent that visual traits, including staple length, character (staple crimp), staple definition, tippiness, style and staple entanglement, are related to clean fleece weight in animals of similar live weight and mean fibre diameter (MFD) from the same flock. Measurements were made over 9 shearing periods on a population of castrated Angora males (wethers) goats representing the current range and diversity of genetic origins in Australia, including South African, Texan and interbred admixtures of these and Australian sources (these different genetic origins are defined as Breed in this work). Data on genetic origin, sire, dam, lifetime characteristics (date of birth, dam age, birth weight, birth parity (single or twin), weaning weight), live weight, fleece growth and visual fleece attributes were recorded. A restricted maximum likelihood (REML) model was developed to relate clean fleece weight with age, MFD, average fleece-free live weight, lifetime characteristics and visual fleece attributes. There were separate linear responses of clean fleece weight to MFD and staple length for each age group, a quadratic response to the square root of average fleece-free live weight, an effect of sire breed and linear responses to dam age, staple definition score and character. Depending on age at shearing, the increase in clean fleece weight was between about 50 and 80. g for each increase of 1. μm in MFD. At similar MFD, clean fleece weight was generally greater at summer shearings compared with winter shearings. There was a strong increase in clean fleece weight with average fleece-free live weight up to around 50. kg but little response in clean fleece weight for animals larger than 50. kg. There was some evidence of a smaller increase in clean fleece weight as the age of dam increased. There was an effect of Breed in the model but this effect disappeared when a random sire effect was included in the model. There was a positive response to staple length at some age groups but the response did not differ from zero in other age groups. This response varied from negligible to about 70. g per 1. cm increase in staple length. Clean fleece weight increased about 40. g per unit increase in staple definition score and increased about 30. g for every 4 units increase in the number of staple crimps. There was no evidence that clean fleece weight was affected by staple style, staple tip score or staple entanglement score or lifetime factors such as birth weight, date of birth, birth parity, or weaning weight. The results show that using a combination of measuring MFD and visually assessing the fleece for staple length, staple definition and crimps can help identify the most profitable Angora goats. In this process, the objective measurement of MFD appears essential. Visual assessment will provide some extra benefit in identifying these animals above that provided by measuring MFD alone. Animal size should be considered by mohair producers when identifying more productive mohair producing animals. © 2014 Elsevier B.V.

Lifetime and fleece quality traits associated with the occurrence of entangled mohair staples

Staple entanglement in mohair fleeces occurs when adhesions form between longer and faster growing fibres and shorter and slower growing fibres. This results in accentuated crimp of the longer fibres and an "apparently" reduced staple length. The appearance in the fleece of Angora goats of staple entanglements can lead to the downgrading of the mohair to poorer style and shorter length grades, resulting in up to 60% price reductions. This study examined how staple entanglement score (SES) is related to lifetime factors of Angora goats, and how this relationship can be explained by variations in animal size and fleece attributes. SES was scored using a five-point scale: 5, long free fibres easily separated as no adhesions; 4, some adhesions between fibres; 3, some effort to separate fibres as many adhesions; 2, many adhesions, staple fibres entangled, shortening of staple; 1, very entangled and shortened staple. Measurements were made over 9 shearing periods on a population of Angora castrated males (wethers) goats representing the current range and diversity of genetic origins in Australia, including South African, Texan and interbred admixtures of these and Australian sources. Data on genetic origin, sire, dam, date of birth, dam age, birth weight, birth parity, weaning weight, live weight, fleece growth and fleece attributes were recorded. Two restricted maximum likelihood (REML) models were developed to relate SES with age, animal lifetime factors, fleece quality attributes and live weight. One model allowed fleece quality and live weight traits in the model and the other excluded these traits. Staple entanglement was almost eliminated in mohair harvested from goats shorn every 3. months but was common in mohair from goats shorn twice or once per year. SES was less in goats of Texan genetic background, and was generally less in winter grown mohair. SES was higher for mohair with low fibre curvature (FC, 10°/mm) and a high clean washing yield (CWY, 90%) compared with mohair with low FC and lower CWY (80%), and compared with all mohair with high FC (18°/mm). The response of SES to shearing regime, genetic background, shearing season, age of goat and a response to dam age were almost identical whether or not an adjustment was made for CWY and FC. There was a moderate amount of variability due to sires and individuals. We can conclude that a large part of these effects observed, namely breed, dam age, sire, and a component of the FC and CWY effects, are genetic. Mohair producers can manage the genetic effects by careful selection of sires, especially avoiding those with low CWY or high FC, and avoiding sires with higher levels of staple entanglement or that have produced progeny with higher levels of staple entanglement. Also, unidentified environmental effects are affecting staple entanglement, although a lack of a live weight change effect on entanglement indicates that this effect might not be due to nutrition. © 2013 Elsevier B.V.

Synthesis and performance of itaconic acid/acrylamide/sodium styrene sulfonate as a self-adapting retarder for oil well cement

This journal is © The Royal Society of Chemistry. A novel self-adapting retarder itaconic acid/acrylamide/sodium styrene sulfonate (IA/AM/SSS, hereinafter referred to as PIAS) was synthesized by free-radical, aqueous-solution polymerization and characterized by FTIR and TG. The optimum reaction conditions of polymerization were obtained from orthogonal experiments (L3³) and subsequent data analysis. According to the evaluation as a retarder, the PIAS made it possible to obtain both a long thickening time and a swift compressive strength development for cement slurry, and therefore the applicable range of bottom hole circulation temperatures to the cement slurry has been widened to 60-180°C. Moreover, the working mechanism of the self-adapting retarder PIAS was found to rely on the change of spatial structure of the molecules to retard the hydration of the cement. This paper also expounds that the delayed coagulation of the cement slurry is attributed to adsorption, chelation and "poisoning" effects of the PIAS molecules on the surface of hydrated particles or ions through XRD and SEM analyses.

Effects of fly ash and silica fume on disintegration of alkali-activated slag at temperature exposure of 50°C

The compressive strength of alkali-activated slag (AAS) paste can be adversely affected by temperature. AAS paste loses its strength when exposed to 50°C for 24 hours. The objective of the current investigation is to evaluate two different mineral admixtures, i.e. fly ash and silica fume, in preventing AAS paste from strength loss. The effect of the above admixtures at various dosages on strength loss was assessed by measuring the retention of compressive strength of samples after exposed to 50°C. Results indicate that the admixtures reduced strength loss. Compared with the fly ash, the silica fume performs better at preventing AAS paste from strength loss. After exposure to 50°C, the use of silica fume to replace 15% of slag reduces the strength loss by 70%. The possible reason for this is discussed based on x-ray diffraction results.

Distribution of carbon nanotubes in fresh ordinary Portland cement pastes: understanding from a two-phase perspective

Significant research advances have been made in the field of carbon nanotube (CNT) reinforced ordinary Portland cement (OPC) paste composites in recent years. However, the distribution of CNTs in fresh OPC paste is yet to be fully researched and quantified, thereby creating a technical barrier to CNT utilization in concrete construction. In this study, fresh OPC paste was treated as a two-phase material containing solid particles (cement grains) and liquid solutions (pore solutions). A centrifugation-based technique was proposed to separate these two phases and the presence of CNTs in each phase was quantified. UV-Vis spectrometry showed that the degree of dispersion can achieve above 90 wt% using polycarboxylate superplasticizer. The results suggested an upper limit of 0.26 wt% for CNT addition into water before mixing with OPC, and the dispersion was found to be stable for at least 4 hours. Based on scanning electron imaging, the adsorption phenomenon of CNTs on OPC grains with size less than 4 μm was discovered. Energy-dispersive X-ray spectroscopy indicated these adsorptive particles have lower Ca to Si ratio. It was observed that about 0.5 mg of CNTs per gram of OPC grains was adsorbed in solid OPC grains in typical fresh OPC pastes. On the basis of these results, a conceptual model was proposed for the distribution of CNTs in fresh OPC paste where about 33 wt% of the CNTs stay in pore solution and 65 wt% of CNTs are adsorbed on OPC grains.