Mining gassy coals

This paper reviews the basic factors and practice of mining gassy coals worldwide. It then suggests how changes need to be made to Australian mining methods to deal with the challenges of mining deeper and gassier coals

Lower carboniferous shelf carbonate palaeo-environments in North Wales

PhD ThesisThe Lower Carboniferous (Asbian and Lower Brigantian) of North Wales in the vicinity of Llangollen and Oswestry, records the deposition of about 40 shelf carbonate regressive cycles during a gradual transgression onto the north eastern flanks of the Anglo-Welsh Landmass (St Georges Land). This sequence was deposited during the major eustatic cycles (mesothems) D5a to D6b.NER

Synthesis of new 5-fluorouracil photosensitiser conjugates for use as prodrugs in the photodynamic therapy for cancer

A major limitation to cancer chemotherapy is the non-selectivity of the drug. One such drug that is used extensively to combat cancer is the pyrimidine derivative 5- fluorouracil (5-FU). However, its associated high toxicity and side effects has limited its clinical use. This in turn has challenged chemists to explore 5-FU prodrug derivatives in order to find a selective, non-toxic form. Although libraries of 5-FU prodrugs have been reported, selectivity still remains a problem and needs improvement. It was therefore our goal to try and improve 5-FU selectivity by designing a 5-FU prodrug that could be selectively delivered to the cancerous tissue where it could be activated. To achieve this we designed a 5-FU produg based on the general tumour activated prodrug (TAP) model concept i.e. triggers, linker and effector. It is known that nitro-aromatic moieties can be reduced by the hypoxic conditions associated with tumour cells hence, we can use these moieties as triggers to activate the 5-FU prodrug. Seven such compounds were synthesised and incubated with 4T1 cancer cell lines for 72 hrs, however only two of the synthesised compounds (52) and (53) showed significant increase in cytotoxicity under hypoxic conditions, thus indicating that activation by endogenous one-electron reductases was occurring. Photosensitisers used in photodynamic therapy (PDT) have been found to selectively accumulate in the cellular organelles of cancerous tissue. By exploiting this phenomena we coupled 5-FURD and the four synthesised nitro-5-FURD prodrugs to the photosensitiser dihydroxysilicon phthalocyanine. This in turn generated the five novel Bis(5-fluorouridine) phthalocyaninosilicon derivatives, thus allowing the photosensitiser to selectively carry the nitro-aromatic-5-FURD prodrug to the cancerous tissue, where the 5-FURD prodrug is activated thus releasing the 5-FU. However, this not only allows for the selective delivery of the 5-FU prodrug but generates a third generation photosensitiser that can be used in PDT application. However, the tumour reduction conditions may not be suitable for optimal activation of our nitro-aromatic prodrugs via the nitroreductase enzymes in the “dark”, we therefore propose two alternative possibilities for activation via (1) the action of gene directed enzyme prodrug therapy (GDEPT) and E.coli or (2) activation through the consequence of oxidative stress on the cell via the release of excess cellular reductase. It was found that of eleven 5-FU prodrugs tested on the SW480 and 4T1 cancer cell lines two (59) and (58) gave similar IC50 values as that for the 5-FU drug and that three of the prodrugs (53), (59) and (69) gave lower anti-invasion activity then the 5-FU drug. We report the synthesis of a novel prodrug 2’,3’-isopropylidene-5,-0-((-4” S,5” R)-Nacetyl- 2’ ’ ,2” -dimethyl-4 ’ ’ -phenyl-1 ” ,3 ” -oxazolidine-5 ’ ’ -carboxylate)-fluorouridine 102). This design incorporates a lipophillic handle coupled to 5-fluorouridine. This compound was tested on SW480 and 4T1 cancer cell lines, however no cell death was observed at the concentrations used, instead growth inducement behaviour was exhibited. Following a SAR study this was attributed to (1) 5-fluorouridine being in the protected form of 2,3-isoprpoylidene-5-fluorouridine, thus preventing the formation of 5-fluorouracil metabolites and (2) the presence of the lipophillic ester slowing down its activation

Directive Effects in Substituted Ferrocenes

This study describes some electrophilic substitutions of methylthio-, chloro-, and methoxy- ferrocene. The experiments were carried out in an attempt to determine the directive effects operative in these compounds. The aminomethylation of methylthioferrocene afforded the three (1,2; 1,1' and 1,3) isomeric dimethylaminomethyl-methylthioferrocenes, which were converted via their methiodides to the corresponding methyl-methylthioferrocenes These compounds were then converted to the corresponding thiocyanates, eg. 1-thiocyanato-1'-methylferrocene, and thence to the corresponding disulphides, e.g. di-(1'-methyIferrocenyl)disulphide. An independent synthesis of di-(1'-methyIferrocenyl)disulphide from 1-carboxyferrocene-1'-sulphonic acid provided conclusive identification of this compound. The site reactivities, as determined from the weights of isomeric methyl-methylthioferrocenes isolated, indicate that the methylthio group is activating in nature. Chloroferrocene was found to acetylate exclusively in the unsubstituted ring, thus demonstrating the deactivating effect of the chloro substituent A new route to ferrocenylboronic acid via ferrocenyl-boronyl dichloride, greatly simplified the preparation of methoxyferrocene. When methoxyferrocene was subjected to Friedel-Crafts acetylation, a mixture of the three (1,2; 1,1' and 1,3) isomeric acetyl-methoxyferrocenes was isolated. These products were identified after reduction, as the corresponding ethyl-methoxyferrocenes. Site reactivities calculated from weights of isomeric ethyl= methoxyferrocenes, isolated from two different reduction methods (LiA1lH4-AlCl3 and Clemmensen reductions), provided unsatisfactory results. Aminomethylation of methoxyferrocene yielded a mixture of the three isomeric dimethylaminemethyl-methoxyferrocenes, which were identlfled, after reduction of the mixture of methiodides, as the corresponding methyl-methozyferrocenes. Site reactivities calculated from these reduction products showed the methoxy group to be activating in nature. The displacement of ferrocene substituents by protons was observed in certain reactions. Methylthio- and methoxy-ferrocene on treatment with aluminium trichloride, afforded not only ferrocene, but mixtures of the isomeric di(methyIthio)- and dimethoxy-ferrocenes. A similar treatment of chloroferrocene furnished only ferrocene

Phylogeography and Population Structure in Highly Mobile Marine Taxa in the Western Indian Ocean: Bottlenose Dolphins (Tursiops spp.) and Common Dolphins (Delphinus sp.)

In the marine environment, where barriers to dispersal are limited, taxa normally exhibit genetic homogeneity across large spatial scales. Extraordinarily, marine mammals regularly exhibit genetic differentiation within their cruising range. Furthermore, recent radiation in Delphininae has resulted in several closely related species that remain taxonomically unresolved, particularly bottlenose dolphins (BND) Tursiops spp. and common dolphins (CD) Delphinus spp., making these taxa interesting for studying evolutionary processes. Using mitogenomes and a multi-locus dataset, BNDs from the northwest Indian Ocean (IO) were compared with other recognized species/ecotypes around the world. A new (third) lineage of Indo-Pacific BND, T. aduncus, was identified from the region. Reconstructions of ancestral biogeography and divergence date estimates, suggest a divergence mechanism within T. aduncus that coincides with climate change over the Pleistocene. Reconstructions of ancestral morphology suggest a coastal ancestry for BNDs. Significant population structure was exhibited between T. aduncus populations in the western IO based on mtDNA control region sequences and 14 microsatellite loci. Genetic subdivision appears to correlate with habitat heterogeneity across the study area, which may be driving differentiation through local adaption. Traditional and geometric morphometric techniques were used to investigate congruency between genetic and phenotypic differentiation of three BND lineages in the northwest IO. Strong differences were exhibited in morphology between common BNDs, T. truncatus, and T. aduncus. The T. aduncus lineages were similar, however significant differences in morphology were evident. Significant genetic structure was evident between CD populations off Portugal, South Africa and Oman, based on mtDNA sequences and 14 microsatellites. Further analyses support the taxonomic designation of D. capensis tropicalis in the northwest IO. Both genera exhibit significant population structure over spatial scales outdistanced by their dispersal abilities. Contemporary and historic environmental heterogeneity are suggested as drivers for this structure. Further evidence is provided for the northwest/northern IO as a region of evolutionary endemism, which will inform regional conservation initiatives

Dealing with bursts – a new approach

This paper categorises the different types of coal bursts and gas outbursts in terms of their mechanisms. It is considered to be essentially impossible to predict when one of these events may occur. However, it is possible in many of the cases to predict the velocity of ejection and hence the distance with which particles may travel including bouncing and rolling and sliding. Keeping beyond this stand-off distance ensures the safety of workers from impact. Where gassy fault gouge exists there is no such safe distance. The material involved may be ejected in the form of a turbulent flow which has been described as a coal storm and which can travel great distances. This also involves large amounts of gas with the inherent problems of explosive mixtures. Locating, and determining the size of such geological features is therefore of great importance. Methods of doing this are discussed

Coal measure rocks and their properties

Coal measure rocks tend to have anisotropic and elastically non-linear behaviour. Understanding this is a key to understanding strata behaviour in coal mines. This paper discusses which properties matter and how they can be measured. Some new test methods are introduced. The paper also discusses the relevance of geophysics in determining these properties

Groups 5 and 6 Terminal Hydrazido(2−) Complexes: N_β Substituent Effects on Ligand-to-Metal Charge-Transfer Energies and Oxidation States

Brightly colored terminal hydrazido(2−) (dme)MCl_3(NNR_2) (dme = 1,2-dimethoxyethane; M = Nb, Ta; R = alkyl, aryl) or (MeCN)WCl_4(NNR_2) complexes have been synthesized and characterized. Perturbing the electronic environment of the β (NR_2) nitrogen affects the energy of the lowest-energy charge-transfer (CT) transition in these complexes. For group 5 complexes, increasing the energy of the N_β lone pair decreases the ligand-to-metal CT (LMCT) energy, except for electron-rich niobium dialkylhydrazides, which pyramidalize N_β in order to reduce the overlap between the Nb═Nα π bond and the Nβ lone pair. For W complexes, increasing the energy of N_β eventually leads to reduction from formally [W^(VI)≡N–NR_2] with a hydrazido(2−) ligand to [W^(IV)═N═NR_2] with a neutral 1,1-diazene ligand. The photophysical properties of these complexes highlight the potential redox noninnocence of hydrazido ligands, which could lead to ligand- and/or metal-based redox chemistry in early transition metal derivatives