The influence of inorganic materials on the pyrolysis of polytetrafluoroethylene. Part 1 : the sulfates and fluorides of Al, Zn, Cu, Ni, Co, Fe and Mn

The thermal decomposition of PTFE intimately mixed with the solid sulfates and fluorides of selected metals (Al2(SO4)3, ZnSO4, CuSO4, NiSO4, CoSO4, FeSO4, AlF3, CuF2, NiF2, CoF2, FeF2 and MnF2) was investigated by TGA-FTIR. It was found that the sulfates affect the rate of pyrolysis with CuSO4 lowering mass-loss onset temperature by 60 °C. The fluorides have no effect on the pyrolysis rate, with the exception of AlF3 which lowers the onset temperature by 35 °C. It was also found that Al2(SO4)3 and NiSO4 moderately increase the yield of hexafluoropropylene, and that AlF3 shifts the product composition to almost exclusively hexafluoropropylene and hexafluoroethane.National Research Foundation of South Africa and the Department of Science and Technology’s Fluorochemical Expansion Initiative.http://www.elsevier.com/locate/fluorhb201

Influence of initiators on the sintering discolouration of PTFE

PTFE homopolymer synthesised using ammonium persulfate initiator discolours at sintering temperatures of approximately 380 °C. No report on this phenomenon is available in the open literature. To shed light on the problem, PTFE samples were synthesised using various initiators and different pH buffers. The initiators used included ammonium persulfate, sodium persulfate, potassium permanganate, di-tertiary butyl peroxide and hydrogen peroxide. Borax and potassium carbonate were used as the buffering agents. The samples were pressed into discs and sintered at 380 °C. The samples were analysed using FTIR and Raman spectroscopy to determine the influence of decomposition of the end-groups during sintering. Each initiator resulted in unique end-groups, with a suggestion of multiple termination reactions in several of the samples. The discolouration of the samples occurs because of amorphous carbon deposition into the polymer matrix after elimination from the end-groups during sintering. The level of discolouration is dependent on the type and concentration of initiator used.http://www.elsevier.com/locate/fluor2020-01-01hj2018Chemical Engineerin

Isolated brachioradialis metastasis of gastric adenocarcinoma after R0 resection

Background Gastric cancer is the fifth most common cancer worldwide, with an incidence of 6.72 per 100,000 people. Thirty-two percent of gastric cancer patients will live 5 years after diagnosis. Single-site metastasis is noted in 26% of patients with gastric cancer, most commonly in the liver (48%), peritoneum (32%), lung (15%), and bone (12%). Here, a case is presented in which a single skeletal muscle metastasis appeared after appropriate resection and treatment. Case presentation A 63-year-old man underwent neoadjuvant chemotherapy and a multivisceral en bloc R0 resection. Final pathology showed no evidence of lymph node metastasis with 31 negative lymph nodes. Four months postoperatively, the patient was found to have a rapidly growing biopsy-proven extremity soft tissue gastric metastasis within the brachioradialis muscle. He subsequently underwent metastasectomy and immunotherapy. Conclusion This case is a rare example of an isolated extremity metastasis of gastric adenocarcinoma in the setting of an R0 resection of the primary tumor and negative nodal disease on final pathology, suggestive of hematogenous spread. We review the biology, workup, and management of gastric cancer and highlight new advancements in the treatment of this aggressive cancer

Microwave digestion of zircon with ammonium acid fluoride: derivation of kinetic parameters from non-isothermal reaction data

Zircon is notoriously inert. Aggressive processing methods such as alkaline fusion are conventionally used to extract zirconium values from the mineral. In this study results are presented with respect to microwave digestion of zircon using ammonium acid fluoride (NH4F·1.5HF). Two distinct experimental methods were used. In the first method the reaction was followed in the temperature range of 100 to 200 °C, for a full reaction period of 60 min at each temperature. The secondmethod comprised successive digestion periods interrupted bywashing and re-introduction of fresh acid fluoride at a series of reaction temperatures varying between 120 and 240 °C. Complete digestion was achieved with the latter technique. The kinetics is shown to be controlled by product-layer diffusion. The two data sets were combined to derive consistent temperature-dependent kinetic parameters. A facile numerical technique for extracting these parameters from the experimental data is used.The Advanced Metals Initiative of the Department of Science and Technology of South Africa.http://www.elsevier.com/locate/ijimprohb201

The Application of Unsupervised Clustering Methods to Alzheimer’s Disease

Clustering is a powerful machine learning tool for detecting structures in datasets. In the medical field, clustering has been proven to be a powerful tool for discovering patterns and structure in labeled and unlabeled datasets. Unlike supervised methods, clustering is an unsupervised method that works on datasets in which there is no outcome (target) variable nor is anything known about the relationship between the observations, that is, unlabeled data. In this paper, we focus on studying and reviewing clustering methods that have been applied to datasets of neurological diseases, especially Alzheimer’s disease (AD). The aim is to provide insights into which clustering technique is more suitable for partitioning patients of AD based on their similarity. This is important as clustering algorithms can find patterns across patients that are difficult for medical practitioners to find. We further discuss the implications of the use of clustering algorithms in the treatment of AD. We found that clustering analysis can point to several features that underlie the conversion from early-stage AD to advanced AD. Furthermore, future work can apply semi-clustering algorithms on AD datasets, which will enhance clusters by including additional information

TGA-FTIR characterisation of bamboo wood, napier grass, pine wood and peach pips for gasification applications

The pyrolysis characteristics of four biomass materials (bamboo, Napier grass, pine and peach pips) were studied in an inert atmosphere using a simultaneous TGA-FTIR instrument. The behaviour of these materials under non-isothermal conditions and at three different heating rates (20, 100 and 200 °C/min) were compared. The gasses released during TGA analysis were analysed using inline FTIR. Higher heating rates were found to increase conversion and had lower activation energies. Napier grass has the lowest conversion which could be due to the amount of silicon contained in most grasses. A distinguishable hemicellulose decomposition peak was detected on the DTG curve of the peach pips. Pine wood has the highest conversion (~88%) of the four biomass materials. The mean conversion achieved for the other materials was approximately 75%. The kinetic parameters of each material computed using a model fitting method are reported. The dehydration stage in general displayed lower activation energies than the active and passive pyrolysis stages.South African Nuclear Corporation; the National Research Foundation; and the Department of Science and Technology.http://www.bjta.com.bram2018Chemical Engineerin

Patterns of stressful life events and polygenic scores for five mental disorders and neuroticism among adults with depression

The dominant (‘general’) version of the diathesis-stress theory of depression views stressors and genetic vulnerability as independent risks. In the Australian Genetics of Depression Study (N = 14,146; 75% female), we tested whether polygenic scores (PGS) for major depression, bipolar disorder, schizophrenia, anxiety, ADHD, and neuroticism were associated with reported exposure to 32 childhood, past-year, lifetime, and accumulated stressful life events (SLEs). In false discovery rate-corrected models, the clearest PGS-SLE relationships were for the ADHD- and depression-PGSs, and to a lesser extent, the anxiety- and schizophrenia-PGSs. We describe the associations for childhood and accumulated SLEs, and the 2–3 strongest past-year/lifetime SLE associations. Higher ADHD-PGS was associated with all childhood SLEs (emotional abuse, emotional neglect, physical neglect; ORs = 1.09–1.14; p’s < 1.3 × 10−5), more accumulated SLEs, and reported exposure to sudden violent death (OR = 1.23; p = 3.6 × 10−5), legal troubles (OR = 1.15; p = 0.003), and sudden accidental death (OR = 1.14; p = 0.006). Higher depression-PGS was associated with all childhood SLEs (ORs = 1.07–1.12; p’s < 0.013), more accumulated SLEs, and severe human suffering (OR = 1.17; p = 0.003), assault with a weapon (OR = 1.12; p = 0.003), and living in unpleasant surroundings (OR = 1.11; p = 0.001). Higher anxiety-PGS was associated with childhood emotional abuse (OR = 1.08; p = 1.6 × 10−4), more accumulated SLEs, and serious accident (OR = 1.23; p = 0.004), physical assault (OR = 1.08; p = 2.2 × 10−4), and transportation accident (OR = 1.07; p = 0.001). Higher schizophrenia-PGS was associated with all childhood SLEs (ORs = 1.12–1.19; p’s < 9.3−8), more accumulated SLEs, and severe human suffering (OR = 1.16; p = 0.003). Higher neuroticism-PGS was associated with living in unpleasant surroundings (OR = 1.09; p = 0.007) and major financial troubles (OR = 1.06; p = 0.014). A reversed pattern was seen for the bipolar-PGS, with lower odds of reported physical assault (OR = 0.95; p = 0.014), major financial troubles (OR = 0.93; p = 0.004), and living in unpleasant surroundings (OR = 0.92; p = 0.007). Genetic risk for several mental disorders influences reported exposure to SLEs among adults with moderately severe, recurrent depression. Our findings emphasise that stressors and diatheses are inter-dependent and challenge diagnosis and subtyping (e.g., reactive/endogenous) based on life events