Frequency Dependent Rheology of Vesicular Rhyolite

Frequency dependent rheology of magmas may result from the presence of inclusions (bubbles, crystals) in the melt and/or from viscoelastic behavior of the melt itself. With the addition of deformable inclusions to a melt possessing viscoelastic properties one might expect changes in the relaxation spectrum of the shear stresses of the material (e.g., broadening of the relaxation spectrum) resulting from the viscously deformable geometry of the second phase. We have begun to investigate the effect of bubbles on the frequency dependent rheology of rhyolite melt. The present study deals with the rheology of bubble-free and vesicular rhyolite melts containing spherical voids of 10 and 30 vol %. We used a sinusoidal torsion deformation device. Vesicular rhyolite melts were generated by the melting (at 1 bar) of an Armenian obsidian (Dry Fountain, Erevan, Armenia) and Little Glass Mountain obsidian (California). The real and imaginary parts of shear viscosity and shear modulus have been determined in a frequency range of 0.005–10 Hz and temperature range of 600°–900°C. The relaxed shear viscosities of samples obtained at low frequencies and high temperatures compare well with data previously obtained by parallel plate viscometry. The relaxed shear viscosity of vesicular rhyolites decreases progressively with increasing bubble content. The relaxation spectrum for rhyolite melt without bubbles has an asymmetric form and fits an extended exponent relaxation. The presence of deformable bubbles results in an imaginary component of the shear modulus that becomes more symmetrical and extends into the low-frequency/high-temperature range. The internal friction Q −1 is unaffected in the high-frequency/low-temperature range by the presence of bubbles and depends on the bubble content in the high-temperature/low-frequency range. The present work, in combination with the previous study of Stein and Spera (1992), illustrates that magma viscosity can either increase or decrease with bubble content, depending upon the rate of style of strain during magmatic flow

Colorectal cancer stages transcriptome analysis

Colorectal cancer (CRC) is the third most common cancer and the second leading cause of cancer-related deaths in the United States. The purpose of this study was to evaluate the gene expression differences in different stages of CRC. Gene expression data on 433 CRC patient samples were obtained from The Cancer Genome Atlas (TCGA). Gene expression differences were evaluated across CRC stages using linear regression. Genes with p 0.001 in expression differences were evaluated further in principal component analysis and genes with p 0.0001 were evaluated further in gene set enrichment analysis. A total of 377 patients with gene expression data in 20,532 genes were included in the final analysis. The numbers of patients in stage I through IV were 59, 147, 116 and 55, respectively. NEK4 gene, which encodes for NIMA related kinase 4, was differentially expressed across the four stages of CRC. The stage I patients had the highest expression of NEK4 genes, while the stage IV patients had the lowest expressions (p = 9*10−6 ). Ten other genes (RNF34, HIST3H2BB, NUDT6, LRCh4, GLB1L, HIST2H4A, TMEM79, AMIGO2, C20orf135 and SPSB3) had p value of 0.0001 in the differential expression analysis. Principal component analysis indicated that the patients from the 4 clinical stages do not appear to have distinct gene expression pattern. Network-based and pathway-based gene set enrichment analyses showed that these 11 genes map to multiple pathways such as meiotic synapsis and packaging of telomere ends, etc. Ten of these 11 genes were linked to Gene Ontology terms such as nucleosome, DNA packaging complex and protein-DNA interactions. The protein complex-based gene set analysis showed that four genes were involved in H2AX complex II. This study identified a small number of genes that might be associated with clinical stages of CRC. Our analysis was not able to find a molecular basis for the current clinical staging for CRC based on the gene expression patterns

The gut microbial metabolite formate exacerbates colorectal cancer progression

The gut microbiome is a key player in the immunomodulatory and protumorigenic microenvironment during colorectal cancer (CRC), as different gut-derived bacteria can induce tumour growth. However, the crosstalk between the gut microbiome and the host in relation to tumour cell metabolism remains largely unexplored. Here we show that formate, a metabolite produced by the CRC-associated bacterium Fusobacterium nucleatum, promotes CRC development. We describe molecular signatures linking CRC phenotypes with Fusobacterium abundance. Cocultures of F. nucleatum with patient-derived CRC cells display protumorigenic effects, along with a metabolic shift towards increased formate secretion and cancer glutamine metabolism. We further show that microbiome-derived formate drives CRC tumour invasion by triggering AhR signalling, while increasing cancer stemness. Finally, F. nucleatum or formate treatment in mice leads to increased tumour incidence or size, and Th17 cell expansion, which can favour proinflammatory profiles. Moving beyond observational studies, we identify formate as a gut-derived oncometabolite that is relevant for CRC progression

Effects of Catalyst Pretreatment on Carbon Nanotube Synthesis from Methane Using Thin Stainless-Steel Foil as Catalyst by Chemical Vapor Deposition Method

Synthesis of carbon nanotubes (CNTs) was carried out using methane as a carbon source via the chemical vapor deposition (CVD) method. A thin stainless-steel foil was used as catalyst for CNT growth. Our results revealed that pretreatment step of the stainless-steel foil as a catalyst plays an important role in CNT formation. In our experiments, a catalyst pretreatment temperature of 850 °C or 950 °C was found to facilitate the creation of Fe- and Cr-rich particles are active sites on the foil surface, leading to CNT formation. It is noted that the size of metallic particles after pretreatment is closely related to the diameter of the synthesized CNTs. It is interesting that a shorter catalyst pretreatment brings the growth of semiconducting typed CNTs while a longer pretreatment creates metallic CNTs. This finding might lead to a process for improving the quality of CNTs grown on steel foil as catalyst

Production of renewable biofuels and chemicals by processing bio-feedstock in conventional petroleum refineries

The influence of catalyst characteristics, i.e., acidity and porosity on the product distribution in the cracking of triglyceride-rich biomass under fluid catalytic cracking (FCC) conditions is reported. It has found that the degradation degree of triglyceride molecules is strongly dependent on the catalysts’ acidity. The higher density of acid sites enhances the conversion of triglycerides to lighter products such as gaseous products and gasoline-range hydrocarbons. The formation of gasolinerange aromatics and light olefins (propene and ethene) is favored in the medium pore channel of H-ZSM-5. On the other hand, heavier olefins such as gasoline-range and C4 olefins are formed preferentially in the large pore structure of zeolite Y based FCC catalyst (Midas-BSR). With both catalysts, triglyceride molecules are mainly converted to a mixture of hydrocarbons, which can be used as liquid fuels and platform chemicals. Hence, the utilization of the existing FCC units in conventional petroleum refineries for processing of triglyceride based feedstock, in particular waste cooking oil may open the way for production of renewable liquid fuels and chemicals in the near future.Bài báo trình bày kết quả nghiên cứu khả năng tích hợp sản xuất nhiên liệu sinh học và hóa phẩm từ nguồn nguyên liệu tái tạo sinh khối giầu triglyceride bằng công nghệ cracking xúc tác tấng sôi (FCC) trong nhà máy lọc dầu. Kết quả nghiên cứu cho thấy xúc tác có ảnh hưởng mạnh đến hiệu quả chuyển hóa triglyceride thành hydrocarbon. Tính acid của xúc tác càng mạnh thì độ chuyển hóa càng cao và thu được nhiều sản phẩm nhẹ hơn như xăng và các olefin nhẹ. Xúc tác vi mao quản trung bình như H-ZSM-5 có độ chọn lọc cao với hợp chất vòng thơm thuộc phân đoạn xăng và olefin nhẹ như propylen và ethylen. Với kích thước vi mao quản lớn, xúc tác công nghiệp FCC dựa trên zeolite Y ưu tiên hình thành C4 olefins và các olefin trong phân đoạn xăng. Ở điều kiện phản ứng của quá trình FCC, triglyceride chuyển hóa hiệu quả thành hydrocarbon mà có thể sử dụng làm xăng sinh học cho động cơ và olefin nhẹ làm nguyên liệu cho tổng hợp hóa dầu

Production of renewable biofuels and chemicals by processing bio-feedstock in conventional petroleum refineries

The influence of catalyst characteristics, i.e., acidity and porosity on the product distribution in the cracking of triglyceride-rich biomass under fluid catalytic cracking (FCC) conditions is reported. It has found that the degradation degree of triglyceride molecules is strongly dependent on the catalysts’ acidity. The higher density of acid sites enhances the conversion of triglycerides to lighter products such as gaseous products and gasoline-range hydrocarbons. The formation of gasolinerange aromatics and light olefins (propene and ethene) is favored in the medium pore channel of H-ZSM-5. On the other hand, heavier olefins such as gasoline-range and C4 olefins are formed preferentially in the large pore structure of zeolite Y based FCC catalyst (Midas-BSR). With both catalysts, triglyceride molecules are mainly converted to a mixture of hydrocarbons, which can be used as liquid fuels and platform chemicals. Hence, the utilization of the existing FCC units in conventional petroleum refineries for processing of triglyceride based feedstock, in particular waste cooking oil may open the way for production of renewable liquid fuels and chemicals in the near future.Bài báo trình bày kết quả nghiên cứu khả năng tích hợp sản xuất nhiên liệu sinh học và hóa phẩm từ nguồn nguyên liệu tái tạo sinh khối giầu triglyceride bằng công nghệ cracking xúc tác tấng sôi (FCC) trong nhà máy lọc dầu. Kết quả nghiên cứu cho thấy xúc tác có ảnh hưởng mạnh đến hiệu quả chuyển hóa triglyceride thành hydrocarbon. Tính acid của xúc tác càng mạnh thì độ chuyển hóa càng cao và thu được nhiều sản phẩm nhẹ hơn như xăng và các olefin nhẹ. Xúc tác vi mao quản trung bình như H-ZSM-5 có độ chọn lọc cao với hợp chất vòng thơm thuộc phân đoạn xăng và olefin nhẹ như propylen và ethylen. Với kích thước vi mao quản lớn, xúc tác công nghiệp FCC dựa trên zeolite Y ưu tiên hình thành C4 olefins và các olefin trong phân đoạn xăng. Ở điều kiện phản ứng của quá trình FCC, triglyceride chuyển hóa hiệu quả thành hydrocarbon mà có thể sử dụng làm xăng sinh học cho động cơ và olefin nhẹ làm nguyên liệu cho tổng hợp hóa dầu

Catalytic Cracking of Triglyceride-Rich Biomass toward Lower Olefins over a Nano-ZSM-5/SBA-15 Analog Composite

The catalytic cracking of triglyceride-rich biomass toward C2–C4 olefins was evaluated over a hierarchically textured nano-ZSM-5/SBA-15 analog composite (ZSC-24) under fluid catalytic cracking (FCC) conditions. The experiments were performed on a fully automated Single-Receiver Short-Contact-Time Microactivity Test unit (SR-SCT-MAT, Grace Davison) at 550 °C and different catalyst-to-oil mass ratios (0–1.2 g∙g−1). The ZSC-24 catalyst is very effective for transformation of triglycerides to valuable hydrocarbons, particularly lower olefins. The selectivity to C2–C4 olefins is remarkably high (>90%) throughout the investigated catalyst-to-oil ratio range. The superior catalytic performance of the ZSC-24 catalyst can be attributed to the combination of its medium acid site amount and improved molecular transport provided by the bimodal pore system, which effectively suppresses the secondary reactions of primarily formed lower olefins