Secondary Overgrowth Research Articles

Characteristics and control factors of feldspar dissolution in gravity flow sandstone of Chang 7 Member, Triassic Yanchang Formation, Ordos Basin, NW China

To clarify the formation and distribution of feldspar dissolution pores and predict the distribution of high-quality reservoir in gravity flow sandstone of the 7th member of Triassic Yanchang Formation (Chang 7 Member) in the Ordos Basin, thin sections, scanning electron microscopy, energy spectrum analysis, X-ray diffraction whole rock analysis, and dissolution experiments are employed in this study to investigate the characteristics and control factors of feldspar dissolution pores. The results show that: (1) Three types of diagenetic processes are observed in the feldspar of Chang 7 sandstone in the study area: secondary overgrowth of feldspar, replacement by clay and calcite, and dissolution of detrital feldspar. (2) The feldspar dissolution of Chang 7 tight sandstone is caused by organic acid, and is further affected by the type of feldspar, the degree of early feldspar alteration, and the buffering effect of mica debris on organic acid. (3) Feldspars have varying degrees of dissolution. Potassium feldspar is more susceptible to dissolution than plagioclase. Among potassium feldspar, orthoclase is more soluble than microcline, and unaltered feldspar is more soluble than early kaolinized or sericitized feldspar. (4) The dissolution experiment demonstrated that the presence of mica can hinder the dissolution of feldspar. Mica of the same mass has a significantly stronger capacity to consume organic acids than feldspar. (5) Dissolution pores in feldspar of Chang 7 Member are more abundant in areas with low mica content, and they improve the reservoir physical properties, while in areas with high mica content, the number of feldspar dissolution pores decreases significantly.

Fibro-Adipose Vascular Anomaly (FAVA): Not Another Vascular Anagram.

Background. Fibro-adipose vascular anomaly (FAVA) is a rare benign mesenchymal lesion. Characterized primarily by intramuscular vascular malformation with secondary overgrowth of other mesenchymal elements, particularly fibro-adipose tissue, the condition is sometimes complicated by nonspecific clinical and imaging features, causing diagnostic dilemma. Herein, we attempted to outline and correlate the clinical characteristics, imaging findings, and histopathological features of this unusual entity. Method. The study design was retrospective in nature. Computerized database of our institute was searched for tumors, and archived slides were reviewed. Pertinent clinical data including imaging findings and treatment details were also recovered for correlation. Result. Among total of 24 patients identified, mean age was approximately 16 years, with the presence of nearly equal gender distribution. Pain along with swelling was most common symptoms with the presence of movement limitation, in few. Most lesions were long-standing and anatomically confined to lower limb with no side predilection. Using imaging, the majority of the lesions were identified as vascular anomaly or venous malformation, with FAVA being a differential diagnosis in few lesions. However, in a couple of patients, likelihood of mesenchymal tumors was also suggested, radiologically. On histology, the lesions showed the presence of clustered back to back, abnormal thin-walled, variably dilated, blood-filled sac-like vessels amid skeletal muscle bundles, along with extensive fibro-adipose tissue and variably atrophic skeletal muscle bundles, at the periphery, diagnostic of FAVA. Conclusion. Owing to the presence of overlapping clinical and imaging features, FAVA is often misdiagnosed, causing dilemma in clinical management. Clinical, radiological, and histopathological correlation is thereby warranted for clinching the correct diagnosis.

Alternating acid and alkaline diagenesis in the Shahejie Formation of E12 structure in the Laizhou Bay Sag, Bohai Bay Basin

The high-quality reservoirs in the Shahejie Formation of the Laizhou Bay Sag, Bohai Bay Basin, Eastern China formed in the Paleogene saline lacustrine environment and show complex diagenetic evolutionary processes caused by alternating acid and alkaline fluids. Through observations under an optical microscope and a scanning electron microscope, casting thin sections, and plane porosity measurements, this study investigated the diagenesis differences in the third member of the Shahejie Formation (Es3 Member) in the root and central portions of a fan delta in the E12 structure in the eastern Laizhou Bay Sag, respectively. The Es3 reservoirs in the well A-1 which have no any hydrocarbon shows, are relatively tight, and have high argillaceous content, poor particle sorting, strong mechanical compaction, and intense carbonate cementation due to long-term activities of alkaline fluids. Moreover, they were not altered by organic acid due to the far lateral distance from source rocks. By contrast, the Es3 reservoirs in the well A-2 with hydrocarbon accumulations, contain an anomalously high porosity zone due to the superimposition of five episodes of alternate acid-alkaline fluids. The diagenetic fluids controlling the formation of the high-quality Es3 reservoirs are sourced from connate saline pore waters, gypsum dehydration, salt diapir, and organic acid. Moreover, chlorite coats in the reservoirs in the well A-2 inhibit secondary overgrowth of quartz and, thus, protect primary pores. The chlorite coats and alkaline-acid dissolution alterations are critical to the formation of the high-quality reservoirs in well A-2.

Taphonomic study of Chuaria fossils from the Ediacaran Lantian biota of South China

The Chuaria is the most common fossils in the Ediacaran Lantian biota (approximately 600 Ma) of South China which represents one of the earliest-known macroscopic eukaryotic fossil assemblages with high morphological diversity. Although great majority of the Lantian Chuaria fossils are preserved as carbonaceous compressions, Chuaria has been reported to be commonly preserved as pyritization enveloped by aluminosilicate minerals in the upper Member II of the Lantian Formation. The outer minerals that envelope the pyrite layer have been assigned to quartz or aluminosilicate clay minerals. However, their exact mineral compositions as well as whether these minerals have contributed to the exceptional preservation of Ediacaran Lantian Chuaria, remain unclear. We employed light microscopy, field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), and Raman spectroscopy techniques to revisit the preservation of pyritized Chuaria from the Lantian biota. Our taphonomic experiments show that pyritized Chuaria fossils are enveloped by platy minerals that are a complex mixture of quartz and magnesium-rich aluminosilicates. Integrated mineral and structural pattern analyses show that these quartz and clay minerals are both secondary overgrowth on Chuaria internal mold, which probably formed as a diagenetic product concurrent with carbonate dissolution in the Lantian black shales. Their formation is probably regulated by local micro-environment near the Chuaria bodies. These enveloped minerals may facilitate preservation and identification of Chuaria fossils, but they are probably not involved in the initial fossilization process as the early diagenetic pyritization has done.

Morphology of framboidal pyrite and its textural evolution: Evidence from the Logatchev area, Mid-Atlantic Ridge

The special and representative polymorphous pyrites of the Logatchev area, Mid-Atlantic Ridge, have a close evolution relationship. There are relatively complete pyrite intermediates undergoing a series of evolutions from disordered nano-micron crystals → framboids → colloidal and subhedral structures. This study focuses on a sulfide-bearing tuff sample of the Logatchev area and presents the detailed mineralogical, textural and geochemical results of a series of intermediate products, from pyrite framboids to subhedral crystals, using results from secondary ion mass spectrometry, field emission scanning electron microscopy, electron backscattered diffraction, and electron microprobes. Framboids packed with nanocrystals are significantly with negative δ34S (−28.3 to −17.4‰), probably formed via organoclastic sulfate reduction (OSR) in the seawater column or shallow marine sediment. And their associated microcrystal framboids have less-negative δ34S value (−22.3 to −8.8‰) and high Cu/Zn ratio, which are interpreted as framboids continuous growth by venting fluids with high temperature in an open system. During the diagenetic stage, the evolution of framboidal pyrites to subhedral crystals occurs mainly through two ways: cementation and rearrangement after growth. As an intermediate, the δ34S values of cemented framboids (−7.6 to +8.7‰) are close to the colloidal and subhedral structure pyrites (+9.1 to +11.2‰), reflecting the subsequent precipitation of pyrite and secondary overgrowth in a closed environment after burial. During the recrystallization process from nano-micron crystals to cemented framboids to colloidal or subhedral structures, the decreasing trend of SiO2 contents (come from the surrounding basement) and increasing Fe, S, Mo contents revealed the consequence of continuous expulsion of silicate in the intergranular pore space, which provides evidence for framboids aggregated and evolving to euhedral pyrite. Some intermediates from framboids to massive pyrites have a certain local ordering. Regulated by surface energy, grains in some framboidal pyrites are physically rotated and repositioned during the growth process, which show either 〈100〉 or 〈111〉 preferred orientations. The planes with higher energy are combined to form a regular arrangement and assembled into a polygonal frame until it evolves into a subhedral structure. The size uniformity of grains derived from framboidal pyrite is key to aggregation and self-organization. The research results are helpful for understanding the genesis mechanism of framboidal pyrite and its evolution process to a euhedral structure, which is of great significance to explore the structural growth of pyrite aggregates and the changes in the environmental response.

S9B-03 SESSION 9B: FACE RESEARCH - PART II SOMATIC ARTERIOVENOUS MALFORMATION MAP2K1 MUTATION CAUSES CARTILAGE OVERGROWTH BY A CELL NON-AUTONOMOUS MECHANISM

Introduction: Arteriovenous malformation (AVM) is a fast-flow, congenital vascular anomaly that is locally destructive and characterized by abnormal connections between arteries and veins. We previously reported that AVMs contain somatic mutations in MAP2K1 which are enriched in blood vessels. Overtime AVMs enlarge to cause significant morbidity. The purpose of this study was to determine if tissue overgrowth associated with AVM was caused by direct or indirect effects of a MAP2K1 mutation (i.e., cell-autonomous or cell-non autonomous). Methods: AVMs affecting the auricle cause overgrowth of the cartilage and overlying soft-tissue resulting in a prominent ear. Because cartilage is a unique tissue that does not contain vasculature, we used this clinical scenario to gain insight into the pathophysiology of how MAP2K1 mutations cause AVM enlargement. We obtained cartilage and its overlying skin/subcutis during a clinically-indicated otoplasty procedure to improve the appearance of the patient with an AVM of the ear. The cartilage was separated from the overlying skin/subcutis grossly and the skin/subcutis was tested with droplet digital PCR (ddPCR) for MAP2K1 mutation (p.K57N). Because MAP2K1 mutations are known to be enriched in endothelial cells (ECs), cartilage was subjected to laser capture microdissection (LCM) to ensure that cartilage being tested for MAP2K1 mutations was not contaminated by microscopic tissue containing blood vessels. LCM was performed on frozen section slides and genomic DNA was extracted from cartilage and adjacent connective tissue and measured for the abundance of mutant MAP2K1 alleles. Results: Skin/subcutaneous tissue from the ear AVM contained a mutation in MAP2K1 (p.K57N); the whole tissue mutant allele frequency was 3.1%. Staining with hematoxylin, eosin, and alcian blue delineated cartilage from the surrounding vessel-rich connective tissue. MAP2K1 (p.K57N) mutations were found in microscopic connective tissue adjacent to the cartilage (mutant allele frequency: 7.5%). MAP2K1 mutations were not identified in the cartilage. Conclusion:MAP2K1 mutations in AVMs are not found in cartilage and thus, the likely mechanism of cartilage overgrowth is paracrine signaling from adjacent mutant blood vessels (i.e., cell-non autonomous). MAP2K1 inhibitors might inhibit secondary overgrowth of tissues in AVM adjacent to blood vessels containing MAP2K1 mutations.

Giant Secondary Overgrowth of Type-1 Pulmonary Cystic Airway Malformation Upon Development of Anaplastic Lymphoma Kinase–Rearranged Adenocarcinoma

Giant Secondary Overgrowth of Type-1 Pulmonary Cystic Airway Malformation Upon Development of Anaplastic Lymphoma Kinase–Rearranged Adenocarcinoma

Diagenesis of Chang6 Formation of Hu2 block, Huanjiang oilfield, Ordos Basin

ABSTRACTThree mian diagenetic processes, compaction, cementation and dissolution of Chang6 sandstone in Hu2 block of Huanjiang oilfield were identified and their impact on the tight reservoir quality were analyzed. Four pore types, intergranular, intragranular, moldic and micropores were identified. Porosity and permeability of low-energy facies with high level of muddy content were generally lower. A rapid loss of primary porosity was caused by compaction, proved by the abrupt change tendency at approximate depth of 2130m. Calcite was the dominant cement which plugged the intergranular pores, whereas other minerals like secondary overgrowth, kaolinite and illite also contributed to tightening the reservoir.

Lactoferricin/verbascoside topical emulsion: a possible alternative treatment for atopic dermatitis in dogs

Atopic dermatitis affects 3–15% of the general dog population and it has been diagnosed by veterinarians up to 58% of dogs affected with skin disease. It is usually a life-long pathology which can be controlled, but it can be seldom cured. The present investigation describes a case study in which lactoferricin and verbascoside are part of a formulation to obtain a dermatological lotion for canine dermatitis treatment. The study was an open-label trial design of two-week treatment. Thirty-eight dogs (23 females and 15 males), with atopic dermatitis and secondary bacterial or yeast overgrowth have been included. During treatment period the total clinical score progressively decreased associated with an improvement in clinical signs. No adverse effects were reported in any of the treated dogs. The present research suggests that daily applications of tested emulsion are effective in reducing bacterial overgrowth and clinical signs in skin folds and atopic dermatitis.

Sediment Composition of the Thakuran River Basin of the Sunderbans

Thakuran River sediments are typical estuarine. Lithogenic constituents are dominant with about 85-90% in bulk and biogenic components constitute the rest (10-15%). Quartz, feldspars, mica, lithic fragments and some heavy minerals are the main terrigenous constituents. Secondary overgrowth of quartz with multiple rims of inclusions suggests their derivation from sedimentary rocks of different cycles of sedimentation. The heavy mineral assemblage in the sediments lead to conclude that the sediments have been derived from the acid igneous rocks of the Himalayas in the north and the metamorphic rocks of the Precambrian shields of the west and north-west of Bengal Basin. Benthic foraminiferal assemblage indicates a shallow water, moderate to low salinity environment of deposition.

The role of skeletal micro-architecture in diagenesis and dating of Acropora palmata

Past variations in global sea-level reflect continental ice volume, a crucial factor for understanding the Earth’s climate system. The Caribbean coral Acropora palmata typically forms dense stands in very shallow water and therefore fossil samples mark past sea-level. Uranium-series methods are commonly used to establish a chronology for fossil coral reefs, but are compromised by post mortem diagenetic changes to coral skeleton. Current screening approaches are unable to identify all altered samples, whilst models that attempt to correct for ‘open-system’ behaviour are not applicable across all diagenetic scenarios. In order to better understand how U-series geochemistry varies spatially with respect to diagenetic textures, we examine these aspects in relation to skeletal micro-structure and intra-crystalline amino acids, comparing an unaltered modern coral with a fossil A. palmata colony containing zones of diagenetic alteration (secondary overgrowth of aragonite, calcite cement and dissolution features). We demonstrate that the process of skeletogenesis in A. palmata causes heterogeneity in porosity, which can account for the observed spatial distribution of diagenetic features; this in turn explains the spatially-systematic trends in U-series geochemistry and consequently, U-series age. We propose a scenario that emphasises the importance of through-flow of meteoric waters, invoking both U-loss and absorption of mobilised U and Th daughter isotopes. We recommend selective sampling of low porosity A. palmata skeleton to obtain the most reliable U-series ages. We demonstrate that intra-crystalline amino acid racemisation (AAR) can be applied as a relative dating tool in Pleistocene A. palmata samples that have suffered heavy dissolution and are therefore unsuitable for U-series analyses. Based on relatively high intra-crystalline concentrations and appropriate racemisation rates, glutamic acid and valine are most suited to dating mid-late Pleistocene A. palmata. Significantly, the best-preserved material in the fossil specimen yields a U-series age of 165±8ka, recording a paleo sea-level of −35±7 msl during the MIS 6.5 interstadial on Barbados.

Assessment of the Reaction Time on the Morphology and Quality of Carbon Nanotubes – Silica Microparticles

Carbon nanotube has been grafted in-situ on the surface of spherical silica gel via floating-catalyst chemical vapour deposition method. The reaction temperature was set to be 760°C and 5wt. % of ferrocene catalyst (dissolved in toluene) injected into the furnace at a rate of 0.04ml/min. The reaction time was varied from 1 hour to 8hours, with one hour interval. It was found that the reaction time of 3hours yields the best quality hybrid particles. Prolonging the reaction time more than 3hours resulted in the formation of CNT that consists of thicker tubes, based on the observation via Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscope (TEM). Secondary overgrowth was observed via TEM for tubes synthesized at 7hours and 8hours. These results were in agreement with Raman Spectroscopy analysis where the IG/ID ratio were very small, indicating high defects and impurities in the samples synthesized at reaction time higher than 3hours.

Alteration patterns of chromian spinels from La Cabaña peridotite, south-central Chile

La Cabana peridotite is part of a dismembered ophiolite complex located within the metamorphic basement of the Coastal Cordillera of south-central Chile, and is the only location in Chile were Cr-spinels have been described so far. The La Cabana peridotite is part of the Western Series unit, which comprises meta-sedimentary rocks, metabasites, and serpentinized ultramafic rocks. This unit has been affected by greenschist-facies metamorphism with reported peak PT conditions of 7.0–9.3 kbar and 380°–420 °C. Within La Cabana peridotite Cr-spinels are present in two localities: Lavanderos and Centinela Bajo. In Lavanderos, Cr-spinel occurs in small chromitite pods and as accessory/disseminated grains with a porous or spongy texture in serpentinite, whereas in Centinela Bajo Cr-spinel is present as accessory zoned grains in partly serpentinized dunites, and in chromitite blocks. All Cr-spinels display variable degrees of alteration to Fe2+-rich chromite with a variation trend of major elements from chromite to Fe2+-rich chromite similar to those observed in other locations, i.e., an increase in Fe2O3 and FeO, a decrease in Al2O3 and MgO. Cr2O3 content increases from chromite to Fe2+-rich chromite in chromitite pods from Lavanderos and chromitite blocks from Centinela Bajo, but decreases in ferrian chromite zones in accessory grains from Centinela Bajo. The minor element (Ti, V, Zn, Ni) content is mostly low and does not exceed 0.4 wt.%, with the exception of MnO ( 0.5 in ferrian chromite and Cr-magnetite. Interpretation of the data obtained and Cr-spinel textures indicate that the alteration of Cr-spinel is a progressive process that involves in its initial stages the reaction of chromite with olivine under water-saturated conditions to produce clinochlore and Fe2+-rich chromite. During this stage the chromite can also incorporate Ni, Mn, and/or Zn from the serpentinization fluids. As alteration progresses, Fe2+-rich chromite loses mass resulting in the development of a spongy texture. In a later stage and under more oxidizing conditions Fe3+ is incorporated in chromite/Fe2+-rich chromite shifting its composition to an Fe3+-rich chromite (i.e., ferrian chromite). Depending on the fluid/rock and Cr-spinel/silicate ratios, Cr-magnetite can also form over Fe2+-rich chromite and/or ferrian chromite as a secondary overgrowth. The compositional changes observed in Cr-spinels from La Cabana reflect the initial stages of alteration under serpentinization conditions. Results from this study show that the alteration of Cr-spinels is dependent on temperature. The degree and extent of alteration (formation of Fe2+-rich and/or ferrian chromite) are controlled by the redox nature of the fluids, the Cr-spinel/silicate and the fluid/rock ratios.

Revision and evaluation of the systematic affinity of the calcitarch genusPithonellabased on exquisitely preserved Turonian material from Tanzania

Extraordinarily well-preserved pithonellid microfossils (calcitarchs, “calcispheres”) from the Turonian (upper Cretaceous) of Tanzania reveal previously unknown morphological traits, crystallographic patterns, and chemical signatures, providing new insight to this enigmatic group of microfossils. Using combined transmitted-reflected light microscopy, scanning electron microscope imagery, electron microprobe elemental analysis and stable isotope geochemistry, the present study reveals four new aspects of the genusPithonella, notably, the following. An affinity with cyst-forming organisms, potentially the dinoflagellates, is indicated by the presence of a hatch opening and corresponding operculum. The pristine outer wall architecture consists of thin, smooth shingle-shaped plates with regular rows of slit-shaped pores and an apical sub-angular or circular pore. This primary surface pattern is significantly different from previous descriptions of an outer wall consisting of “parquet-shaped” prismatic crystal rows; this latter surface pattern is formed by secondary overgrowth. The crystallographic pattern of the inner wall is crypto-crystalline. Unaltered pithonellids reveal a calcite chemistry characterized by comparably high Mg-contents, relatively enriched stable carbon isotope values, and stable oxygen values indicating a surface water habitat. Based on these previously unseen traits, the diagnosis of the genusPithonellais emended. A new species,Pithonella diconica, is described from the lower-middle Turonian sediments of Tanzania.

Systemic Sclerosis in Small Bowel

e t s P t p A man with systemic sclerosis was admitted with progressive abdominal distention and vomiting. Previusly, he had recurrent episodes of vomiting. There was no istory of abdominal surgery, and a recent colonoscopy was nremarkable. Physical examination showed a tympanitic, disended abdomen with hypoactive bowel sounds. A digital rectal xamination revealed low anal sphincter tone. Laboratory inestigations indicated a total white blood cell count of 0,930/ L and mild hypoalbuminemia (3.5 g/dL). Liver and enal function was normal, and urinalysis showed no protein. A lain abdominal radiograph and computed tomography reealed the dilation of the entire small intestine (Figure A). asting and fluid supplementation relieved his symptoms. Upper endoscopy revealed reflux esophagitis. Double-balloon ndoscopy by oral route revealed a narrow separation between ircular folds of the small intestine (Figures B and C). Villous tructure was normal. A biopsy specimen from the jejunum howed only mild chronic inflammation. He received a diagnois of systemic sclerosis–related pseudo-obstruction. The paient’s symptoms improved with prokinetic drugs for motility isturbance and antibiotics for bacterial overgrowth. Systemic sclerosis is a multisystem disease characterized by xcess deposition of connective tissue in skin and internal rgans. Gastrointestinal involvement is the most frequent inernal organ complication of systemic sclerosis, with more than 0% of patients experiencing a change in gastrointestinal funcion.1 Impairment in bowel motility leads to stasis of luminal contents and secondary bacterial overgrowth. The European League Against Rheumatism recommends prokinetic drugs for motility disturbance and antibiotic rotating therapy for bacterial overgrowth or malabsorption in systemic sclerosis.2 Typical ndoscopic appearance of small bowel manifestation of sysemic sclerosis is narrow separation between circular folds depite bowel dilation. This sign is referred to as hide-bound. redominant muscle atrophy and collagenous replacement of he outer longitudinal layer relative to the inner circular layer robably account for this characteristic appearance.3

Very Distal Radial Osteotomy For Madelung's Deformity

Madelung's deformity results from arrested or slowed growth of the volar-palmar portion of the distal radial epiphysis. The deformity is characterized by increased volar and ulnar tilt of the articular surface of the radius and a bow of the distal radius in a palmar direction. When Madelung's deformity produces pain and interferes with function, correction of the deformity of the radius and secondary overgrowth of the ulna is desirable. Although osteotomy of the radius near the junction of the middle and distal thirds allows correction of the bow of the radius and limited correction of palmar tilt, it does not permit correction of ulnar tilt. We describe a very distal radial osteotomy that permits correction of the 3 deformities of the distal radius independently; correction of palmar tilt, ulnar tilt, and the bow of the radius are selected individually. The inherent flexibility makes the procedure technically challenging but allows for maximum independent correction of the components of Madelung's deformity. Early results indicate the procedure provides relief of pain and improved appearance with few complications.

Structural Evolution of Gold Nanorods during Controlled Secondary Growth

Single-crystalline gold nanorods synthesized by the Ag(I)-mediated seeded-growth method (see: El-Sayed, M. A.; Nikoobakht, B. Chem. Mater. 2003, 15, 1957) were used as seeds for the preferential overgrowth of gold on particular crystallographic facets by systematic variation of the conditions during overgrowth. The results support previous reports about the relevance of the cationic surfactant cetyltrimethylammonium bromide (CTAB) and Ag(I) in stabilizing anisotropic particle shapes and demonstrate that the regulation of the amount of ascorbic acid facilitates the preferential overgrowth of {111} crystal facets to form Xi-type particle shapes. Interestingly, secondary overgrowth is found to inevitably result in a loss of particle shape anisotropy. A mechanism based on surface reconstruction is proposed to rationalize the "shape-reversal" that is generally observed in the nanorod growth process, that is, the initial increase and subsequent decrease of particle anisotropy with increasing reaction time. High-resolution electron microscopy analysis of gold nanorods reveals clear evidence for (1 x 2) missing row surface reconstruction of high energetic {110} facets that form during the initial phase during particle growth.

Cyclic polyaniline nanostructures from aqueous/organic interfacial polymerization induced by polyacrylic acid

Cyclic nanostructural polyanilines have been synthesized by means of a simple modified aqueous/organic interfacial polymerization with the aid of polyacrylic acid, and yet only nanofiber nanostructural polyanilines were obtained by conventional interfacial polymerization in the presence of polyacrylic acid. These nanostructures were characterized using TEM, X-ray diffraction and UV–vis. The cyclic polyaniline nanostructures were formed by severe secondary overgrowth through the electrostatic interaction between aniline/oligoaniline and polyacrylic acid chains. The average diameter of the obtained cyclic-structure was ca. 400 nm and its conductivity was 1.06 S/cm.

Activities of chitinolytic enzymes during primary and secondary colonization of wood by basidiomycetous fungi

The nitrogen (N) content of wood is usually suboptimal for fungal colonization. During decomposition of wood, an increasing fraction of the N becomes incorporated into fungal mycelium. Between 5 and 50% of the N in wood-degrading mycelium may be incorporated into chitin. Chitinolytic enzymes render this N available for re-utilization. Here, the activities of chitinolytic enzymes produced by wood-rotting fungi during degradation of spruce (Picea abies) wood were quantified in situ using fluorogenic 4-methylumbelliferyl substrates. A new method was developed that enables spatial quantification of enzyme activities on solid surfaces. All of the three tested fungi produced endochitinases, chitobiosidases and N-acetylhexosaminidases during colonization of wood. N-acetylhexosaminidase activity, and in some cases also chitobiosidase and endochitinase activities, were higher during secondary overgrowth of another fungus than during primary colonization of noncolonized wood. The results suggest that wood-degrading fungi degrade their own cell walls as well as the hyphae of earlier colonizers. Recycling of cell wall material within single mycelia and between fungal individuals during succession may lead to retention of N within woody debris.

Variations of sulfur isotopes in metamorphic rocks from Bamble Sector, southern Norway: a laser probe study

Variations of sulfur isotopes in metamorphic rocks from Bamble Sector, southern Norway, are investigated using a Q-switched, pulsed mode, laser combustion technique. The results indicate that laser-related fractionations are reproducible (1 σ=0.2‰), provided uniform conditions are maintained during analysis. Bamble is a Precambrian high-grade metamorphic terrain. A transition from amphibolite- to granulite-facies occurs across the 25-km width of the Sector. Supracrustal rocks of mid-Proterozoic ages were intruded by felsic and mafic magmas and metamorphosed during the Sveconorwegian orogenic episode. Earlier studies indicated that Bamble rocks equilibrated under a relatively high f O 2 , 2–3 log units above QFM buffer, during peak metamorphism [J. Geochemical Exploration 31 (1989) 149; J. Geology 100 (1992) 447; Contrib. Mineral Petrol. 1139 (2000) 180], which led to phase changes in sulfides. Pyrrhotite, or Po mss, has variably been replaced by pyrite±magnetite. Mantling of pyrite by magnetite is common. Metasupracrustal rocks display a large variation in δ 34S CDT (−1‰ to +12‰), consistent with data from sedimentary rocks of similar age. No distinction can be made between amphibolite, transition, and granulite zones. The isotopic signature of sulfides was determined by bacteriogenic reduction of seawater sulfate with an initial δ 34S value of 20–30‰. Tonalitic–trondhjemitic gneisses from granulite zone show a large scatter in δ 34S CDT (0‰ to +8‰), implying that the parent magmas were contaminated by sedimentary materials. This is supported by S/Se ratios. Mafic rocks from various metamorphic zones display a clustering of δ 34S CDT values around 0‰, and S/Se ratios in the range 3×10 3 to 6×10 3. This is consistent with a mantle source for S. Ni–Cu sulfide ores locally associated with the mafic rocks, however, are enriched in 34S, indicating the involvement of sedimentary S in the formation of the ores. Mass and isotopic balance calculations indicate that oxidation of pyrrhotite, or Po mss, proceeded without significant addition or removal of S. Sulfur liberated during mantling of Fe–sulfides by magnetite was in a reduced form and reprecipitated in short distances as secondary overgrowth and fracture filling pyrite. The large variation of δ 34S values for the supracrustal rocks, and the preservation of the original isotopic features for various rock units suggest that no isotopic homogenization occurred in spite of the high-grade metamorphism.