Hydrocarbon indication in Rio Bonito Formation sandstone:Implication for CO_(2)storage in São Paulo,Brazil

São Paulo State has witnessed CO_(2)storage-based investigations considering the availability of suitable geologic structures and proximity to primary CO_(2)source sinks related to bioenergy and carbon capture and storage(BECCS)activities.The current study presents the hydrocarbon viability evaluations and CO_(2)storage prospects,focusing on the sandstone units of the Rio Bonito Formation.The objective is to apply petrophysical evaluations with geochemical inputs in predicting future hydrocarbon(gas)production to boost CO_(2)storage within the study location.The study used data from eleven wells with associated wireline logs(gamma ray,resistivity,density,neutron,and sonic)to predict potential hydrocarbon accumulation and fluid mobility in the investigated area.Rock samples(shale and carbonate)obtained from depths>200 m within the study location have shown bitumen presence.Organic geochemistry data of the Rio Bonito Formation shale beds suggest they are potential hydrocarbon source rocks and could have contributed to the gas accumulations within the sandstone units.Some drilled well data,e.g.,CB-1-SP and TI-1-SP,show hydrocarbon(gas)presence based on the typical resistivity and the combined neutron-density responses at depths up to 3400 m,indicating the possibility of other hydrocarbon members apart from the heavy oil(bitumen)observed from the near-surface rocks samples.From the three-dimensional(3-D)model,the free fluid indicator(FFI)is more significant towards the southwest and southeast of the area with deeper depths of occurrence,indicating portions with reasonable hydrocarbon recovery rates and good prospects for CO_(2)injection,circulation and permanent storage.However,future studies based on contemporary datasets are required to establish the hydrocarbon viability further,foster gas production events,and enhance CO_(2)storage possibilities within the region.

Indication and surgical approach for reconstruction with endoprosthesis in bone-associated soft tissue sarcomas:Appropriate case management is vital

It is important for surgeons performing sarcoma surgery to know that bone resection and tumor prosthesis applications in soft tissue sarcomas(STS)have unique features in terms of indication,surgical approach and follow-up,in terms of the management of these cases.Some STS are associated with bone and major neurovascular structures.Bone-associated STS are generally relatively large and relatively deep-seated.Additionally,the tendency for metastasis is high.In some cases,the decision about which structures to resect is difficult.These cases are often accompanied by poor oncological and surgical outcomes.Management of cases should be done by a multidisciplinary team in advanced centers specialized in this field.The surgical team must have sufficient knowledge and experience in the field of limb-sparing surgery.Preoperative evaluation and especially good planning of bone and soft tissue reconstruction are vital.

Potential role of peripheral blood mononuclear cell' s mitochondrial respiratory dysfunction in heart failure severity prediction in patients with cardioverter-defibrillator implantation indications

Background It has been reported that the mitochondrial respiratory dysfunction (MRD) is important mechanisms affecting the heart failure (HF) pathogenesis.We sought to evaluate the potential role of MRD of peripheral blood mononuclear cells (PBMC) in HF severity prediction in patients with cardioverter-defibrillator implantation indications.Methods In this single-center study patients with HF of New York Heart Association (NYHA) Ⅰ-Ⅲ functional class (FC) and cardioverter-defibrillator implantation indications underwent transthoracic echocardiography (TTE) and MRD assessment using PB-MC.Mitochondrial respiration rate (MRR) indicators (pyruvate+malate+adenosine diphosphate;succinate+adenosine diphosphate;pyruvate+malate–adenosine diphosphate[V4.1];succinate–adenosine diphosphate) were calculated.Correlations between HF NYHA FC,TTE and MRR indicators were evaluated.Based on our data,we developed a risk model regarding HF severity.Results Of 53 (100.0%) HF patients,33 (62.3%) had mild exercise intolerance (1stgroup) and 20 (37.7%) had moderate-to-severe exercise intolerance (2ndgroup).Patients with mild exercise intolerance were likely to have a higher V4.1(P<0.001) values.V4.1was independently associated with moderate-to-severe exercise intolerance in univariate and multivariate logistic regression (OR=0.932,95%CI:0.891–0.975,P<0.001).Conclusions The severity of HF is associated with PBMC mitochondrial respiratory dysfunction in patients with cardioverter-defibrillator implantation indications.Our HF severity risk model including V4.1parameters is able to distinguish patients with mild and moderate-to-severe exercise intolerance.Further investigations of their predictive significance are warranted.

Vulvectomy: Indications and Results in the General Surgery Department of the Ignace Deen Chu Hospital in Conakry

Introduction: The aim of this study was to report the indications and evaluate the results of vulvectomy in the general surgery department of Ignace Deen Hospital, CHU Conakry. Materials and Methods: This was a retrospective descriptive study, conducted over a period of five (05) years from January 1, 2018 to December 31, 2022, in the general surgery department of Ignace Deen Hospital, CHU Conakry. We included in our study all patient records in whom vulvectomy was performed. Results: We recorded 15 cases of vulvectomy out of 453 perineal surgeries, i.e. 3.31%, with a mean age of 43.56 years and extremes of 35 and 69 years. Vulvar cancer was the most common diagnosis (46.67%), followed by Buschke-Lowenstein (33.33%) and anal canal cancer extending to the vulva (20%). Six patients had undergone biopsy (40%). Vulvectomy with lymph node dissection was performed in only 9 patients (60%), and all surgical specimens were sent to anatomical pathology (100%). Conclusion: Vulvectomy is a surgical technique most often indicated for the treatment of vulvar cancer.

Splenectomy: Indications in the General Surgery Department of Ignace Deen Hospital

Introduction: Splenectomy is the surgical removal of the spleen. It can be performed during various pathologies, ranging from abdominal trauma to hemoglobinopathies. The progress made in the knowledge of the immune functions of the spleen and the fear of post-splenectomy infectious complications have favored the development of surgical or non-surgical splenic preservation techniques calling into question the dogma of splenectomy. The aim of this study was to determine the indications for splenectomy. Methodology: This was a retrospective, descriptive study lasting 5 years in the general surgery department of the Ignace Deen National Hospital. All files of splenectomized patients were included, our variables were clinical, therapeutic and progressive. Results: We collected 42 cases of splenectomies out of the 2478 surgical procedures performed, representing 1.7% of the department’s surgical activities. The average age was 44 years. The age group of 41 to 50 years was the most represented, i.e. 26% (n = 11) of cases. Sex ratio = 1. Abdominal pain was the reason for consultation in patients, i.e. 100% (n = 42) of cases. The antecedents were dominated by recurrent malaria with 52.3% (n = 22) of cases, then recurrent anemia in 21% (n = 9), and 16.7% (n = 7) had sickle cell disease. Splenomegaly was found in 31 patients, or 73.6%. Ultrasound was performed in all patients. The indications for splenectomy were: isolated splenomegaly with risk of rupture (38%, n = 16), hypersplenism (26%, n = 11) and trauma to the spleen (19.04%, n = 8). Total splenectomy was performed in all cases. The surgical consequences were favorable in 85.7%, (n = 36) with morbidity of 14% (n = 6) and mortality of 9.52% (n = 4). The average length of hospitalization was 10.4 days with extremes of 1 and 22 days. Conclusion: Splenectomy constitutes a relatively common surgical procedure in our context. The indications for splenectomy were isolated splenomegaly with risk of rupture, hypersplenism and trauma to the spleen and total splenectomy was the rule.

Caesarean Section in the Mother and Child University Hospital of N’Djamena: Indications and Prognosis

Introduction: Caesarean section is a surgical procedure which allows childbirth after opening the abdominal wall and the uterus. Objective: To study caesarean section in the N’Djamena Mother and Child University Hospital (NMCUH). Patients and Method: This was a cross-sectional, analytic descriptive study over a 5-month period from 10 January to 10 June 2023, focusing on caesarean sections section in the N’Djamena Mother and Child University Hospital (NMCUH). Studied variables were epidemiological, clinical and prognostic. Patients were divided according to the classification of Robson into 10 groups. Results: During the study period, we recorded 724 caesareans sections among 3,565 deliveries, giving a rate of 20.3%. The age group from 25 to 29 represented 39.2%. The average age was 31.2 ± 2.8 years, with extreme ranging from 14 to 44 years. Nulliparous women accounted for 42% and 26% had at least one previous caesarean section (n = 188). Patients with full-term pregnancies (37 - 40 gestational weeks + 6 days) represented 64.1%. Emergency caesareans accounted for 92.8% (n = 672). Robson’s group 1 was noted to be 40.3%. Hemorrhage was the main intraoperative complication, with 7.2%. In post-operatively, anemia was the main complication at 23.8%. We recorded 16 maternal deaths, giving a maternal death rate of 2.2%. Live newborns accounted for 81.1%. Conclusion: Caesarean section is a common procedure in the CHUME maternity unit. The main indications are those of Robson’s group I. Caesarean sections are associated with both maternal and fetal complications.

Thyroidectomy: Frequency and Indications in the General Surgery Department of the Hôpital National Ignace Deen/CHU de Conakry

Introduction: Thyroidectomy is a surgical procedure to remove all or part of the thyroid gland. The aim of this study was to report the results of thyroidectomy in the general surgery department of the Hôpital national Ignace Deen/CHU de Conakry. Methodology: This was a retrospective study, of seven (07) years (January 1, 2016 - August 31, 2023), in the General Surgery Department of the Ignace Deen National Hospital-CHU in Conakry. We included all records of patients admitted and operated on for thyroidectomy and with up-to-date medical records. The variables were epidemiological, clinical and therapeutic. Results: During the study period, we recorded 3221 cases of surgery, including 40 thyroidectomies (1.24% of cases). The average age was 42.4 years. Women were the most represented, with a sex ratio of 0.16. The reason for consultation was anterior cervical swelling in 86% (n = 25) of cases, followed by signs of cervical compression 21% (n = 6) and signs of thyrotoxicosis 31% (n = 9). Indications for thyroidectomy were dominated by homogeneous goitres in 69% (n = 20) of cases, basedow’s disease in 20.7% (n = 6) and nodular goitres in 6.9% (n = 2) of cases. The surgical procedures were lobo-isthmectomies in 72.4% (n = 21), subtotal thyroidectomies 13.8% (n = 4), total thyroidectomies 10.3% (n = 3). Postoperative follow-up was straightforward in 69% (n = 20). Complications included haemorrhage in 20.7% (n = 6) and recurrence in 6.9% (n = 2). The average hospital stay was 7 days. Conclusion: Thyroidectomy is a relatively frequent surgical procedure in our department. Indications are dominated by homogeneous goitres. Morbidity is related to hemorrhage. Rigorous hemostasis could improve the quality of thyroidectomy.

Research on Geographical Indications and Cultural Heritage of Famous Tea in Hubei

In the study, analysis was made on present situation and development measures of geographical indications and cultural heritage protection of famous teas in Hubei Province. In addition, 8 related suggestions were proposed as well.

Percutaneous endoscopic gastrostomy:Indications,technique,complications and management

Percutaneous endoscopic gastrostomy (PEG) is the preferred route of feeding and nutritional support in patients with a functional gastrointestinal system who require long-term enteral nutrition. Besides its well-known advantages over parenteral nutrition, PEG offers superior access to the gastrointestinal system over surgical methods. Considering that nowadays PEG tube placement is one of the most common endoscopic procedures performed worldwide, knowing its indications and contraindications is of paramount importance in current medicine. PEG tubes are sometimes placed inappropriately in patients unable to tolerate adequate oral intake because of incorrect and unrealistic understanding of their indications and what they can accomplish. Broadly, the two main indications of PEG tube placement are enteral feeding and stomach decompression. On the other hand, distal enteral obstruction, severe uncorrectable coagulopathy and hemodynamic instability constitute the main absolute contraindications for PEG tube placement in hospitalized patients. Although generally considered to be a safe procedure, there is the potential for both minor and major complications. Awareness of these potential complications, as well as understanding routine aftercare of the catheter, can improve the quality of care for patients with a PEG tube. These complications can generally be classified into three major categories: endoscopic technical difficulties, PEG procedure-related complications and late complications associated with PEG tube use and wound care. In this review we describe a variety of minor and major tube-related complications as well as strategies for their management and avoidance. Different methods of percutaneous PEG tube placement into the stomach have been described in the literature with the &#x0201c;pull&#x0201d; technique being the most common method. In the last section of this review, the reader is presented with a brief discussion of these procedures, techniques and related issues. Despite the mentioned PEG tube placement complications, this procedure has gained worldwide popularity as a safe enteral access for nutrition in patients with a functional gastrointestinal system.

Indication Function of Aquatic Algae for Environment

In order to better monitor N and P pollutants, heavy metals, pesticides and other organic pollutants in water areas, we researched sensitivity and tolerance of aquatic algae on water environment and effects of the pollutants on algae population, analyzing toxin and enrichment of pollutants on algae. The results indicated that aquatic alga is a better indicator for some pollutants in water, for which water contamination can be surveyed and analyzed rapidly.

Necessity and indications of invasive treatment for Budd-Chiari syndrome

BACKGROUND:The development of collaterals in Budd-Chiari syndrome has been described and these collaterals play an important role in the presentation of this disease.These collaterals are diagnostic and their use in management strategy has never been evaluated.This study aimed to investigate the indications,feasibility and necessity of invasive treatment for patients with Budd-Chiari syndrome and to determine whether such a strategy is necessary for optimal management.METHODS:Twenty-nine patients who had been treated at our unit were enrolled in this study.Based on physical and biochemical examination,and hemodynamic compensation by collaterals,18 patients underwent radiological intervention (group A),while the other 11 had no invasive treatment (group B).The related hemodynamic parameters were acquired when percutaneous angiography was performed.RESULTS:In group A,all patients underwent successfully inferior vena cava (IVC) balloon angioplasty with or without stenting.Four patients also underwent hepatic vein angioplasty.In these patients,the mean IVC pressure before and after treatment was statistically different (29.3±9.2 vs 15.1±4.6 mmHg,P<0.01).The mean IVC pressure was much lower in group B than in group A (12.9±2.4 vs 29.3±9.2 mmHg,P<0.01),but there was no difference from that of the patients after radiological treatment (12.9±2.4 vs 15.1±4.6 mmHg,P>0.05).Median follow-up was 32.3 months (mean 21.3 months;range 3-61 months).In the course of follow-up,the patients in group A survived with good systemic status except for re-stenosis in one patient who underwent re-canalization of the IVC.In group B,10 patients had good systemic status except one patient who had a meso-caval shunt because of deterioration.CONCLUSIONS:The rationale of 'early diagnosis and early treatment' is not suitable for all patients with Budd-Chiari syndrome.Satisfactory survival can be achieved in some patients without invasive treatment,who are completely compensated by rich collaterals.Nonetheless,a positive treatment procedure should be performed if the patient's situation worsens in the course of regular follow-up.

Epithelioid hemangioendothelioma of the liver as a rare indication for liver transplantation

AIM: To investigate the indications and outcomes of liver transplantation for hepatic epithelioid hemangioendothelioma (HEHE).

Endoscopic pancreatic sphincterotomy:indications,outcome,and a safe stentless technique

AIM Endoscopic pancreatic sphincterotomy is less widely practiced than biliary sphincterotomy, in part because of the lack of firm data regarding its indications and safety. In addition, recent reports of ductal and parenchymal changes occurring after pancreatic stenting raise concerns about the standard practice of stent placement at the time of pancreatic sphincterotomy. We report our experience with pancreatic sphincterotomy and describe the use of a technique involving overnight nasopancreatic drainage rather than stenting.METHODS We reviewed the records of the 164 pancreatic sphincterotomies performed on 160 patients at our institution between January 1, 1991, and October 1, 1996, comparing procedures done with overnight nasopancreatic catheter placement with those done with stenting or no drainage. We also examined the longterm clinical outcome of patients after pancreatic sphincterotomy.RESULTS Of the 164 sphincterotomies, 98 were done with overnight nasopancreatic drainage, 50 with stent placement, and 16 with no drainage. Complications (all pancreatitis) were significantly more frequent in the group with no drainage (125%) as compared with those with drainage (07%); P<0003. Nasopancreatic drainage was as safe as stent placement, with no complications after 98 procedures. Pancreatic sphincterotomy was effective when used as primary therapy, with 64% of patients so treated experiencing complete and longlasting resolution of symptoms after the procedure.CONCLUSION Pancreatic sphincterotomy is safe and effective, although pancreatic drainage is required to reduce the incidence of pancreatitis. Overnight nasopancreatic drainage is the method of choice, as it carries as low a complication rate as stent placement, but without the need for a repeat procedure, and presumably without the risk of ductal and parenchymal damage.

A Review of Research Progress in the Genesis of Colloform Pyrite and Its Environmental Indications

Colloform pyrite is a special form of nano-micro polycrystalline aggregation growth, for which a suitable term is ＂aggregates of nano-micro crystals＂. This kind of colloform texture is observed in various geological bodies, such as ancient sedimentary rocks, modern marine and lake sediments, various types of ore deposits, and modern seafloor hydrothermal vents. This paper summarizes the latest developments and research into the definition, formation mechanisms, and environmental indications of colloform pyrite. There appears to be three main formation mechanisms of colloform pyrite： pseudomorphic replacement; biogenic precipitation; and inorganic precipitation. The morphology, particle size, trace element content and preferential growth orientations of coUoform pyrite microcrystals can be important indicators for sedimentary environments, hydrothermal activity, and ore-forming processes. We suggest that the microscopic features of nano-micro crystals in colloform pyrite and their aggregation growth patterns need further investigation. The relationships between formation mechanisms of colioform pyrite, organic activity and depositional environments require further exploration. To reveal the nature of nano-micro grain aggregation growth in colloform pyrite and analyse its growth environment and evolutionary history, it is supposed to apply nanoscientific and nanotechnological methods, further integrate consideration of macroscopic geological backgrounds and microscopic mineral growth phenomena, combine high-resolution imaging systems and in situ quantitative microanalysis methods and constitute a mergence of earth science, thermodynamics and kinetics, life science, material science, and chemistry in the study.

Predictors of non-response to cardiac resynchronization therapy implantation in patients with class Ⅰ indications: the markedly dilated left ventricular end-diastolic dimension and the presence of fragmented QRS

Background Cardiac resynchronization therapy(CRT)is a highly effective treatment in patients with a class I recommendation.However,a small proportion of the strictly selected patients still fail to respond.This study was designed to identify predictors of non-response in patients with class I indications for CRT and determine the non-response probability of the patients.Methods A total of 296 consecutive patients with a class I recommendation received CRT from January 2009 to January 2017 were retrospectively analyzed.Multivariate logistic regression analysis was performed to identify predictors for non-response(defined as cardiac death,heart transplantation,or HF hospitalization during 1-year follow-up).Results Among 296 patients,30(10.1%)met non-response.Multivariate analysis demonstrated that non-response to CRT was associated with a fragmented QRS(odd ratio(OR)=2.86,95%CI:1.14–7.12;P=0.025)and left ventricular end-diastolic dimension(LVEDD)≥77 mm(OR=3.02,95%CI:1.17–7.82;P=0.022).Patients with both of the predictors had a non-response probability of 46.2%(95%CI:19.1%–73.3%).Conclusion In patients with left bundle branch block and wider QRS duration,the proportion of non-response to CRT is not low in real world.The presence of the dilated LVEDD or fragmented QRS is a strong predictor of non-response to CRT.The probability of non-response in the patients with the two predictors was 46.2%.

Trends in the indications for penetrating keratoplasty in Shandong,2005-2010

AIM: To identify the current indications and the trend shifts for penetrating keraboplasty (PKP) in Shandong. METHODS: The medical charts of all patients who underwent PKP at Shandong Eye Institute from June 1, 2005 to May 31, 2010 were analysed retrospectively. RESULTS: A total of 875 patients (875 eyes) received PKP in this 5-year period, accounting for 61.6% of all corneal transplantation surgeries. The leading indications for PKP were infectious keratitis (37.1%), HSK (19.1%), keratoconus (11.2%), bullous keratopathy (8.5%), regrafting (6.7%) and corneal scarring (4.8%). The percentage of PKP for keratoconus declined year by year, whereas the percentage of bullous keratopathy had a mild annual increase. Fungal infections accounted for 65.2% of the infectious keratitis cases, remaining the leading cause of corneal infection. In addition, 54.1% of bullous keratopathy cases were associated with cataract surgery. The leading initial diagnoses associated with regrafting were infectious keratitis (38.9%), HSK (18.6%) and corneal burn (16.9%). The major causes of regrafting included graft endothelial dysfunction (39.0%), graft ulcer (28.8%) and primary disease recurrence (15.3%). CONCLUSION: Infectious keratitis remained the leading indication for PKP in Shandong, and fungal infections were still the major cause of corneal infections. There was an increasing trend in the percentage of PKP cases indicated for bullous keratopathy but a decline in the same for keratoconus. Even with a decline in the overall proportion among all corneal transplantation surgeries, PKP is still the major corneal transplant choice in Shandong.

Do we have enough evidence for expanding the indications of ESD for EGC?

Endoscopic submucosal dissection(ESD) is the most advanced and representative technique in the field of therapeutic endoscopy and has been used for the treatment of gastrointestinal neoplasms,including early gastric cancer.The major difference and advantage of ESD compared to existing endoscopic resection techniques,such as endoscopic mucosal resection(EMR) and polypectomy,are the width and depth of the resection.Newly developed cutting devices,distal attachable endoscopic accessories,and an advanced electrosurgical unit have helped to overcome the limitations of therapeutic endoscopy in terms of lesion size,location,presence of fibrotic scarring,and accompanying ulcers.As a result,the indications for ESD have been expanded from the classical indication for EMR and polypectomy,and there is now support for a further expansion of ESD indications.At present,the most critical factor to consider in the decision of whether to perform ESD is the probability of unexpected lymph node metastasis.The guidelines for ESD are continually being updated and debated.In this review,we discuss the strengths and weaknesses of the expanded guidelines,based on evidence found in the literature.

Indications for and techniques of keratoplasty at Vietnam National Institute of Ophthalmology

AIM： To report the indications for and techniques of corneal transplantation at Vietnam National Institute of Ophthalmology （VNIO） over a period of 12y （2002-2013）, METHODS： Records of patients who had undergone corneal transplantation at VNIO from January 1, 2002 to January 1, 2014 were reviewed to determine the indication for and type of corneal transplant performed. Patient age, gender, indication for corneal transplantation and surgical technique were recorded and analyzed. RESULTS： Corneal transplantation were underwent in 1390 eyes of 1278 patients with a mean age of 44.9±18.1y during the period under review. The most common indication was infectious corneal ulcer （n=670; 48.2%）, followed by corneal scar （n=333, 24.0% ）, corneal dystrophy （n=138, 9.9%） and failed graft （n=112, 8.1%）. Nearly all procedures performed were penetrating keratoplasty （n=1300, 93.5% ）, with a few lamellar keratoplasty procedures performed： lamellar keratoplasty （n=52, 3.7%）, Descemet＇s stripping automated endothelial keratoplasty （n =27, 1.9% ） and deep anterior lamellar keratoplasty （n =11, 0.8%）.CONCLUSION： While the most common indication for keratoplasty was infectious keratitis, nearly all indications for corneal transplantation were managed with penetrating keratoplasty, However, lamellar keratoplasty techniques, including deep anterior lamellar keratoplasty and Descemet＇s stripping automated endothelial keratoplasty, are being performed with increasing frequency for isolated stromal and endothelial disorders, respectively,

Growth Pattern and Its Indication of Spheroidal Nano-Micro Crystal Aggregates of Pyrite in the Baiyunpu Pb-Zn Polymetallic Deposit, Central Hunan

The Baiyunpu deposit lies in the southwest plunging Dachengshan anticline in central Hunan, which is a large Pb-Zn polymetallic deposit. The orebodies were surrounded by the Qiziqiao Formation limestone in the Middle Devonian, and its geological occurrence is consistent with the wall rocks. A large number of spheroidal pyrite aggregates are found unevenly distributed in the ores. The spheroidal aggregates are made up of kernels and concentric rings. The kernels are composed of approximately epigranular pyrite nanocrystals, while the rings are composed of accumulated pyrite microcrystals growing along the radial direction. The spheroidal pyrite aggregate and its outer zones can be divided into five areas（A–E）. The results of electron probe micro analysis（EPMA） show that from the zone A1 to B, Co/Ni 〈1, the sum of Co and Ni is 0.08%–0.26%, S/Fe increases from 2.06 to 2.15. While from the zone C to E, Ni cannot be detected and S/Fe decreases from 2.22 to 2.08. Powder X-ray diffraction（XRD） analysis in the micro zone shows obvious crystalline characteristics in the aggregates. Moving from the inside outwards, the maximum diffraction peak intensity of the（111） and（220） crystal planes of pyrite increases, and the crystallinity improves. The degree of change in the（111） plane is the most prominent. Considering the theory of crystal growth along with the geologic features of the depositional environment where the spheroidal pyrite aggregates developed, we confirm that the spheroidal aggregates are the result of nano-micro crystalline gathering and growth occurring by the following sequence of processes：nano-crystalline nucleation and growth, gathering into a ball, oriented growth of microcrystals, continuous accumulation, and adjustment of grain boundaries. The formation of the spheroidal pyrite aggregates in the late Qiziqiao Formation of the Middle Devonian occurred in a neutral to weak alkaline and reductive sedimentary environment in the normal oxygen-rich shallowwater carbonate platform edge. The variations in the S/Fe ratio and crystallisation characteristics indicate that during pyrite crystal growth, the sulphur fugacity was high locally and rose constantly, the degree of supersaturation decreased locally and the growth environment was stable relatively.

Geochemical Indications of Possible Gas Hydrates in the Northeastern South China Sea

Gas hydrate, mainly composed of hydrocarbon gas and water, is considered to be a clean energy in the 21st century. Many indicators such as BSRs （Bottom-Simulating Reflections）, which are thought to be related to gas hydrate, are found in the South China Sea （SCS） in recent years. The northeastern part of the SCS is taken as one of the most potentials in the area by many scientists. It is situated in the conjunction of the northern divergent continental margin and the eastern convergent island margin, whose geological settings are much preferable for gas hydrate to occur. Through this study, brightness temperature anomalies recorded by satellite-based thermal infrared remotely sensed images before or within the imminent earthquake, the high content of hydrocarbon gas acid-degassed from subsurface sediment and the high radioactive thermoluminescence value of subsurface sediment were found in the region. Sometimes brightness temperature anomalies alone exist in the surrounding of the Dongsha Islands. The highest content of hydrocarbon gas amounts to 393 μL methane per kilogram sediment and the highest radioactive thermoluminescence value is 31752 unit; their geometric averages are 60.5 μL/kg and 2688.9 unit respectively. What is more inspiring is that there are three sites where the methane contents are up to 243, 268 and 359μL/kg and their radioactive thermoluminescence values are 8430, 9537 and 20826 unit respectively. These three locations are just in the vicinity of one of the highest confident BSRs identified by predecessors. Meanwhile, the anomalies are generally coincident with other results such as headspace gas anomaly in the sediment and chloride anomaly in the interstitial water in the site 1146 of Leg 184. The above-mentioned anomalies are most possibly to indicate the occurrence of gas hydrate in the northeastern SCS.