Cut Samples Research Articles

Organic petrographic and geochemical insights into organic matter derived from land plants and marine algae in the Lark Formation, Danish North Sea

Climatic fluctuations from the Eocene to the Miocene highlight the importance of investigating the paleoenvironment of the latest Eocene to the Middle Miocene Lark Formation in the Danish North Sea. This study investigates immature sedimentary organic matter in the Lark Formation using 54 cuttings samples and one core sample collected from seven wells in the eastern North Sea Basin. Organic petrography and molecular geochemistry analyses were performed to determine the variations in the quantity and origin of allochthonous and autochthonous organic matter. Additionally, the study assesses the impact of climate fluctuations on marine productivity in the eastern North Sea Basin and land plant vegetation at the basin margins during the latest Eocene to the Middle Miocene.The organic matter in the Lark Formation originated from mixed sources, primarily land plants, with a secondary contribution from marine algae. This is indicated by the maceral composition and the types and abundance of aliphatic and aromatic hydrocarbon biomarker compounds. Moreover, the presence of diterpenoids (gymnosperm biomarkers) and non-hopanoid triterpenoids (angiosperm biomarkers) reveals that the allochthonous organic matter originated from conifers and angiosperms.Climatic impacts on land plants and marine algae during the latest Eocene to the Middle Miocene are revealed by several parameters: the Averaged Chain Length (ACL) of land plant waxes, the proportion of coniferous contribution (C/(C + A)), and the whole rock volume percentages of huminite, inertinite (H + I, vol%) and liptinite (L, vol%). The shifts to cooler and drier climates highlighted the cold adaptation of onshore conifers and resulted in the input of higher molecular weight waxy components into the sediments. However, under these conditions, reduced precipitation and runoff resulted in lower amounts of terrigenous organic matter supplied to the basin. Additionally, the drop in water temperature and the warm-affinity of local algae assemblage led to reduced marine productivity. Together, these factors contributed to an overall decrease in organic richness. In contrast, during shifts to warmer and more humid climates, the trend reversed. The contribution of conifers to the floral assemblage diminished, but higher amounts of terrigenous organic matter were transported to the basin due to increased precipitation and runoff. This was accompanied by warmer water temperatures, boosting the productivity of organic-walled microplankton in the marine environment and contributing to greater organic richness.

Mechanical characterization of FDM components made of polyaryletherketone (PAEK) for aerospace applications: a comparison of direct printing and box-cut sample manufacturing strategies

This study delves into the manufacturing strategies employed for fabricating tensile samples utilized in the mechanical characterization of material extrusion (MEX) components constructed with polyaryletherketone (PAEK) for aerospace applications. Two distinct methods were investigated for obtaining tensile test samples: direct cutting and extraction from a box. These methods were examined under both as-printed and annealing conditions. Quasistatic tensile tests were conducted along the building direction to evaluate the impact of processing conditions on the adhesion of overlying layers. The results unveiled significant disparities in mechanical behavior and crystallinity between directly printed samples and those derived from the box. The Young’s modulus exhibited marginal influence; however, the tensile strength of directly printed samples measured at 30 MPa (prior to annealing), corresponding to 50% of the strength observed in samples cut from the box (60 MPa). Moreover, the elongation at rupture of directly printed samples was found to be less than 2%, while that of cut samples exceeded 8%. Notably, directly printed samples exhibited a significant degree of incipient crystallization (12.18%), contrasting with the lower level of crystallinity observed in samples cut from the box (3.27%). These findings underscore the importance of recognizing the limitations associated with direct sample printing, emphasizing its crucial role in accurately characterizing components destined for the aerospace industry. Furthermore, this understanding is pivotal for optimizing the performance and reliability of MEX-printed PAEK components in aerospace engineering applications.

Virulent shiga toxin-producing Escherichia coli (STEC) O157:H7 ST11 isolated from ground beef in Brazil.

In this study, a total of 248 ground beef samples were analyzed for the presence of Shiga toxin-producing Escherichia coli (STEC). Out of these samples, only one (0.4%) tested positive for STEC. Further analysis using PCR confirmed the presence of all tested genes associated with STEC, including stx1, stx2, eae, ehx, uid, rfbO157, and fliCH7 in this isolate. Interestingly, no STEC strains were detected in the remaining 100 beef cut samples or the 100 chicken cut samples, indicating the absence of detectable STEC contamination in those specific samples. The isolated strain exhibited significant cytotoxic activity in Vero cells, indicating its ability to produce cytotoxic Shiga toxins. To further investigate the strain, whole-genome sequencing (WGS) analyses were performed. The resistome analysis revealed the absence of acquired antimicrobial resistance genes, indicating a pan-susceptible phenotype. However, this strain presented chromosomal mutations in gyrA, gyrB, parC, parE, pmrA, pmrB, and folP. Plasmid analysis identified the presence of two plasmids, namely IncFIB(AP001918) and IncFII. The multi-locus sequence typing (MLST) identified the strain as belonging to sequence type (ST) 11, which is associated with E. coli O157:H7 strains. The virulome analysis confirmed the presence of several canonical virulence markers, including stx1, stx2, eae-g01-gamma, ehxA, stx1a-O157, and stx2a-O157. Overall, this study identified for the first time a rare occurrence of STEC contamination in ground beef, with the isolated strain belonging to the highly virulent O157:H7 serotype. These findings contribute to our understanding of STEC prevalence and characteristics in food samples, highlighting the importance of effective food safety measures to prevent potential health risks associated with STEC contamination.

Novel Cardiovascular Stent Based on Hibiscus-Aestivation-Inspired Auxetic Unit Cell

Conventional stents have some limitations, such as dogboning and foreshortening, that can lead to issues like in-stent restenosis and thrombosis. Negative Poisson's ratio stents, called auxetic stents, are known as a solution to overcome these challenges due to their unique deformation mechanism. Auxetic stents are scale-independent, and their behavior depends solely on their geometry. In this study, a novel auxetic unit cell inspired by aestivation mechanism of the Hibiscus flower is designed, developed, and implemented in plane, and a tube to achieve a novel NPR cardiovascular stent. The stent structure is fabricated using two methods, including a novel 7-axis laser cut method capable of producing stents the same size as human blood vessels from an SS 316 L tube, and fused deposition modelling 3D printing at a scale 20 times larger than the metallic sample using PLA filaments. Novel laser cut effectively overcame some challenges in laser cutting stents, including HAZ and thermal shocks. SEM images are taken from the laser cut sample, and the manufacturing method's accuracy and surface quality are investigated. Fabricated metallic and polymeric stent samples proposed negative Poisson's ratio equal to 0.89 with an average of 4.38 and 14.8% errors, respectively, compared with finite element analysis. Finally, the structure's stress, strain energy distribution pattern, and unit cell distribution have been examined. Furthermore, the stent thickness parameter, drug release patch application, and stent implementation process are also investigated using FEM method. Proposed geometry in stent application showed solutions to conventional positive Poisson's ratio stent challenges.

Source rock assessment and organic matter characterization of the Oligocene upper Shahejie and Dongying formations in the Nanpu depression of the saline lacustrine Bohai Bay basin, China: Geochemical, palynological, and mineralogical perspectives

The Bohai Bay Basin, located in eastern China, is a significant petroliferous, non-marine rift basin, underwent intricate tectonic activities throughout the Cenozoic. The Nanpu Depression in the Huanghua sub-basin in the northern part of the basin was controlled by Paleogene rifting and increased subsidence. These geological processes resulted in the deposition of the Shahejie and Dongying formations, which exhibited varying quantities and qualities of organic matter. Eighty drill cuttings samples of the Paleogene First Member (Es1) and the overlying Third (Ed3) and Second (Ed2) members of the Shahejie and Dongying formations, respectively, were investigated. An integrated approach including organic and inorganic geochemistry, palynology, and mineralogy was employed to assess the paleoredox and marine incursion conditions, source rock quality and levels of thermal maturity, and factors that governed organic matter accumulation. Results indicated that the Es1 Member was deposited under anoxic conditions, resulting in the accumulation of organic matter-rich mudstones in the Nanpu Depression. Abundant pollen grains and acritarchs were found in the Es1 Member yielded along with minor occurrences of dinoflagellate cysts, freshwater algae, and spores. Terrestrial palynomorph composition provided evidence of increased terrestrial runoff, while the high abundance of acritarchs, accompanied by some dinoflagellate cysts, confirmed episodes of marine incursion and deposition under hypersaline conditions in the lacustrine Bohai Bay Basin. The Ed2 Member exhibited poor to fair amounts of organic matter and a limited potential of hydrocarbon generation with a variety of kerogen Types, including IV, III, II/III, and II. The Ed3 Member shows fair to good organic matter richness and hydrocarbon potential of kerogen Types III, II/III, and II. The Es1 Member emerged as the most promising source rock within the studied interval, boasting good to excellent organic matter richness, and fair to good hydrocarbon generation potential of kerogen Types III and II/III. Evaluating the thermal maturity of organic matter, based on Tmax and VRo-Eq% and related cross-plots, revealed that the Shahejie and Dongying formations are still in the immature to the early stage of the oil window. The mineralogical composition of the Es1 Member primarily consists of clay and quartz with some carbonate and accessory minerals, such as epigenetic halite, dolomite, and plagioclase. Weak correlations observed between the total organic carbon (TOC) and mineral components indicated that the availability of organic matter was primarily controlled by enhanced production and preservation rather than limited dilution under saline lacustrine, oxygen-deprived, and well-stratified water column conditions. Regional investigations of the Es1 Member confirmed the widespread anoxia and deposition of organic-rich source rocks in the Bohai Bay Basin during the Oligocene.

Chemostratigraphy of the Sherbrook Supersequence – 13 wells from the offshore Otway Basin

An elemental chemostratigraphic study of the offshore Otway Basin has been undertaken as part of a collaboration between Chemostrat and Geoscience Australia, the main aim of which is to better constrain the sequence boundaries of, and within, the Sherbrook Supersequence. This study includes the elemental analysis of 1185 cuttings samples from the Sherbrook Supersequence (and overlying stratigraphy) in 13 offshore wells. Sampling of cuttings was particularly challenging as many of the targeted wells have a paucity of material available for destructive analysis. Inductively Coupled Plasma-Optical Emission Spectrometry and Mass Spectrometry (ICP-OES and MS) analysis was undertaken to establish a regional elemental chemostratigraphic framework of the Sherbrook Supersequence. The resultant framework comprises two chemostratigraphic sequences, seven chemostratigraphic packages and eighteen chemostratigraphic units. While the analysis could not clearly distinguish the base of the Sherbrook Supersequence it has provided valuable insight into correlations between wells, within the Sherbrook and overlying Wangerrip supersequences. Importantly it has confirmed that in the offshore part of the basin sedimentary processes and inputs remain unchanged from the Shipwreck to the Sherbrook (Turonian–Maastrichtian).

Learned Inference of Annual Ring Pattern of Solid Wood

AbstractWe propose a method for inferring the internal anisotropic volumetric texture of a given wood block from annotated photographs of its external surfaces. The global structure of the annual ring pattern is represented using a continuous spatial scalar field referred to as the growth time field (GTF). First, we train a generic neural model that can represent various GTFs using procedurally generated training data. Next, we fit the generic model to the GTF of a given wood block based on surface annotations. Finally, we convert the GTF to an annual ring field (ARF) revealing the layered pattern and apply neural style transfer to render orientation‐dependent small‐scale features and colors on a cut surface. We show rendered results of various physically cut real wood samples. Our method has physical and virtual applications such as cut‐preview before subtractive fabricating solid wood artifacts and simulating object breaking.

PALYNOFACIES STUDIES OF THE LATE CRETACEOUS (TURONIAN-MAASTRICHTIAN) STRATA FROM JAURO JATAU, GONGOLA SUB-BASIN, NORTHERN BENUE TROUGH, NIGERIA

Geographically located within Gombe, Bauchi, and Yobe states, the Gongola Sub-basin has drawn attention from several academics looking to increase Nigeria's oil reserves relative to the inland frontier basins. This paper's goal is to determine the thermal maturity of strata from drill samples of the Fika shales in Nigeria's Northern Benue Trough, Gongola Sub-basin. To predict the well section's maturity and kerogen type, this study uses optical and organic facies studies. Twenty-seven samples of ditch cuttings were prepared using the universally accepted acid palynological procedure. The dispersed mounted slides revealed a variety of pollen, spores, and palynomacerals upon microscopic inspection. The well section under study exhibits a range of thermal maturation from mature to late mature, indicating the possibility of producing oil and gas. This corresponds to a range of thermal alteration values of 4 – 6 and equivalent vitrinite reflectance (%Ro) values of 0.6% – 1.35%. The total recovered Sedimentary Organic Matter (SOM) in this study was classified into Palynomorphs, Amorphous Organic Matter (AOM) and Phytoclasts and plotted on a ternary graph. The Percentage frequencies of AOM, Phytoclast and Palynomorphs were compared with the zones of the Tyson Ternary diagram. Most of the distribution frequencies lie within zones II, IX, VI and Iva suggesting Kerogen types III (gas-prone) and II (oil-prone).

Nutritional Quality and Safety Assessment of Pork Meat Cuts from Romania: Fatty Acids and Elemental Profile.

In this study, the fatty acids and elemental profiles of 53 pork cut samples were determined. To offer insights into their potential health implications, we computed 18 key nutritional indices. These indices included parameters such as saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), unsaturated fatty acids (UFAs), the MUFAs/SFAs ratio, PUFAs/SFAs ratio, atherogenic index (AI), thrombogenic index (TI), the hypocholesterolemic to hypercholesterolemic ratio (h/H), health-promoting index (HPI), hypocholesterolemic index (HI), unsaturation index (UI), saturation index (SI), peroxidizability index (PI), nutritional value index (NVI), hypocholesterolemic index of fatty acids (DFAs), hypercholesterolemic index of fatty acids (OFAs), and the DFAs/OFAs ratio. These indices were calculated based on their fatty acid composition to provide comprehensive nutritional information. A health risk assessment revealed the safety and minimum health risk for the population from consuming the investigated pork cuts using the Target Hazard Quotient (THQ), Hazard Index (HI), and target cancer risk (TR). The ANOVA test showed significant differences in the levels of K, Fe, Mn, Zn, MUFAs, and AI among the pork cut samples. It was noted that by employing the correlation between the fatty acids profile, nutritional indices, and elemental concentrations and an unsupervised statistical method, such as PCA, a perfect separation from the different pork cuts could not be obtained.

Experimental investigation of freeze injury temperatures in trees and their contributing factors based on electrical impedance spectroscopy.

In trees, injuries resulting from subfreezing temperatures can cause damage to the cellular biofilm system, metabolic functions, and fibrous reticulum, and even cell death. Investigating the occurrence of freezing damage and its contributing factors could help understand the mechanisms underlying freezing injury and prevent the subsequent damage in trees. To achieve this, a laboratory experiment was conducted using cut wood samples from Korean pine (Pinus koraiensis Siebold & Zucc) and Simon poplar (Populus simonii Carr.), and the effects of environmental freezing factors, including freezing temperatures, freezing duration, and cooling rate, on the temperature at which freezing injuries occur were examined using the electrical impedance spectroscopy (EIS) method. The semi-lethal temperature (LT50), as an indicator of freezing injury in wood tissue, was theoretically deduced based on the measured extracellular resistance (r e) using EIS. The contributory factors to changes in LT50 were determined and their relationship was established. The results revealed that all freezing factors exhibited significant effects on electrical impedance characteristics (r e, r i, and τ), significantly influencing the LT50 of the wood. Random forest (RF) and support vector machine (SVM) models were used to assess the contribution of the freezing factors and moisture content (MC). Among the factors examined, freezing duration had the greatest impact on LT50, followed by the MC, whereas the contribution of the cooling rate was minimal. The model accuracies were 0.89 and 0.86 for Korean pine and Simon poplar, respectively. The findings of our study illustrate that the occurrence of freezing injury in trees is primarily influenced by the duration of freezing at specific subzero temperatures. Slow cooling combined with prolonged freezing at low subzero temperatures leads to earlier and more severe freezing damage.

Quantitative biostratigraphy and paleoecology of Neogene tropical dinoflagellate cysts

Understanding the biostratigraphy of tropical areas during the Neogene period can be improved by studying dinoflagellate cyst events. These events have traditionally been identified through qualitative analysis. Nevertheless, to obtain consistent data on this subject, we used quantitative and probabilistic analysis of palynological data from the Southern Gulf of Mexico to identify dinoflagellate cyst events in the Neogene era. We analyzed a database of six wells, including 1,005 core and cuttings samples, a change from past qualitative analysis methods. With this quantitative approach with the RASC program, we obtained the Ranking Optimum Sequence (ROS) and compared it with ten published databases from Neogene tropical sites. The ROS identified eleven dinoflagellate species as age markers, we propose a most likely sequence of dinoflagellate cysts bioevents and define three assemblages: “Cantharellus” (Oligocene to early Miocene), “Hyalina” (Miocene), and “Patulum” (middle Miocene to Pleistocene), that can help recognize most Neogene stratigraphic stages in tropical areas. The comparison with the previous databases shows that the Gulf of Mexico and the tropical sites share 60% of the species, which enables age calibration of the optimal sequence and allows us to infer a possible provincial affinity. Additionally, we found a predominance of autotrophic dinocysts during the Neogene in tropical oceans. This trend mirrors the current abundance of gonyaulacoid cysts in tropical and subtropical areas, which has persisted since the Jurassic era.

Geochemical Characteristics of the Mallawa Formation, and its Relationship with the History of Source Rock Formation in the South Makassar Basin, South Sulawesi

A hydrocarbon system to determine the hydrocarbon potential in an area can be determined by the presence of three main components that ensure its existence together, one of main components are source rock. The South Makassar Basin has the potential to have a petroleum system that acts as a source rock for the Mallawa Formation. Source rock is a component of the petroleum system that has the ability to produce and store hydrocarbons, where this rock is generally a rock with fine grains such as coal or shale. Oil and gas exploration in Indonesia is a common thing because there are many prospect areas that have the potential to produce hydrocarbons. The South Makassar Basin is a Tertiary sedimentary basin of land type which is geographically located along West Sulawesi to South Sulawesi and this basin occurs due to tectonics or structures with high frequency. The South Makassar Basin was formed as a result of the expansion of the Makassar Strait which occurred at no younger than the Early Paleocene age where the tectonic consequences would influence the maturation process of the source rocks in the South Makassar Basin. Apart from that, in this research a geochemical method was carried out in the form of laboratory analysis to determine the maturity of the source rock using cuttings samples. So this research provides something new in the exploration of the maturity of source rocks, which in the South Sulawesi area has a complex tectonic setting.

High Power Laser Cutting of SiC-Al2O3 Ceramic Matrix Composites

Machining composite to achieve the desired surface and sub-surface condition, whether through conventional or non-conventional techniques, presents persistent challenges due to their anisotropic thermal characteristics. These challenges escalate when dealing with ceramic matrix composites (CMC) due to their high melting and boiling temperature. This study investigates the surface and sub-surface characteristics of SiC-Al2O3 CMC laser-cut components, produced using a 2 kW quasi-continuous wave laser. The influence of laser parameters such as focal position, cutting speed, number of cutting passes, average power, and assist gas type on surface and sub-surface characteristics have been investigated in detail. The laser cut samples were analysed using white light interferometer, Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and 3D X-ray Computer Tomography (XCT) for both surface and sub-surface characteristics. The effect of laser process parameters on the surface composition, surface topology, and sub-surface thermal defects have been studied in detail. The results revealed that multi-pass cutting (16 pass) can be used to achieve lower thermal affected zone (~200 µm) and reduced surface roughness with an overall cutting speed of 625 mm/min. No delamination was observed with multi-pass cutting. Nitrogen was found to be the most suitable assist gas, as it prevented oxide layer formation across the laser cut SiC-Al2O3 CMC surface.

High-temperature annealing of ( ) β-Ga2O3 substrates for reducing structural defects after diamond sawing

A commercial epi-ready ( ) β-Ga2O3 wafer was investigated upon diamond sawing into pieces measuring 2.5 × 3 mm2. The defect structure and crystallinity in the cut samples has been studied by X-ray diffraction and a selective wet etching technique. The density of defects was estimated from the average value of etch pits calculated, including near-edge regions, and was obtained close to 109 cm−2. Blocks with lattice orientation deviated by angles of 1−3 arcmin, as well as non-stoichiometric fractions with a relative strain about (1.0−1.5) × 10−4 in the [ ] direction, were found. Crystal perfection was shown to decrease significantly towards the cutting lines of the samples. To reduce the number of structural defects and increase the crystal perfection of the samples via increasing defect motion mobility, the thermal annealing was employed. Polygonization and formation of a mosaic structure coupled with dislocation wall appearance upon 3 h of annealing at 1100 °C was observed. The fractions characterized by non-stoichiometry phases and the block deviation disappeared. The annealing for 11 h improved the homogeneity and perfection in the crystals. The average density of the etch pits dropped down significantly to 8 × 106 cm−2.

Identification of individual goat animals by means of near infrared spectroscopy and chemometrics analysis of commercial meat cuts.

Although the identification of animal species and muscles have been reported previously, no studies have been found on the use of NIR spectroscopy to identify individual animals from the analysis of commercial meat cuts. The aim of this study was to evaluate the use of a portable near infrared (NIR) instrument combined with classical chemometrics methods [principal component analysis (PCA) and partial least squares discriminant analysis PLS-DA)] to identify the origin of individual goat animals using the spectral signature of their commercial cut. Samples were collected from several carcasses (6 commercial cuts x 24 animals) sourced from a commercial abattoir in Queensland (Australia). The NIR spectra of the samples were collected using a portable NIR instrument in the wavelength range between 950 and 1600nm. Overall, the PLS-DA models correctly classify 82% and 79% of the individual goat samples using either the goat rack or loin cut samples, respectively. The study demonstrated that NIR spectroscopy was able to identify individual goat animals based on the spectra properties of some of the commercial cut samples analysed (e.g. loin and rack). These results showed the potential of this technique to identify individual animals as an alternative to other laboratory methods and techniques commonly used in meat traceability.

Genotypes of Eruca vesicaria subsp. sativa grown in contrasting field environments differ on transcriptomic and metabolomic levels, significantly impacting nutritional quality.

Rocket (Eruca vesicaria subsp. sativa) is a source of sulfur-containing glucosinolates (GSLs). GSLs and their breakdown hydrolysis products (GHPs) are responsible for health-related benefits, such as anti-cancer and anti-neurodegenerative properties. Understanding how phytochemical composition changes between cultivation environments is key to developing cultivars with improved nutritional quality. Two consecutive harvests (first and second regrowth) of crops, grown in both Italy and the UK, were used to determine the phytochemical and transcriptomic differences between six lines of Eruca. Samples were taken upon delivery from field sites (D0) and after five days of cold storage (D5) for each location. Leaves were analysed for sulfur content, volatile organic compounds (VOCs), GSLs, GHPs, and sugars. Transcriptome data were associated with metabolite profiles to identify differentially expressed genes between plants grown in the two environments. VOC compounds (carbon disulfide, methyl thiocyanate) were associated with growth environment and with differences in sulfur metabolism gene expression (APR2, LSU2, LSU3, SDI1, SiR), GSL biosynthesis (MYB28, FMOGS-OX2) and GHP formation (ESM1, TGG1, TGG2). The concentrations of sugars were an order of magnitude greater in UK grown samples (up to 29.9 mg g-1 dry weight; dw). Sulfur content was significantly higher in the Italy plant samples (11.4 - 20.1 mg g-1 dw), which was in turn associated with higher concentrations of GSLs (pentyl GSL, up to 15.8 μmol g-1 dw; sinigrin, up to 0.005 μmol g-1 dw; glucoraphanin, up to 5.1 μmol g-1 dw; glucorucolamine, up to 23.6 μmol g-1 dw; neoglucobrassicin, up to 5.3 μmol g-1 dw) and hydrolysis products (sativin, up to 13.5 μmol g-1 dw; erucin, up to 1 μmol g-1 dw; sulforaphane, up to 34.7 μmol g-1 dw). VOC profiles of plants cultivated in the UK were distinct from Italy grown plants, with higher relative abundances of alkanes and esters in second cut and shelf-life (D5) samples. The data indicate a significant interaction of cultivar response with environment, highlighting the difficulty of producing Eruca crops with consistent phytochemical and postharvest traits. Genes with differential expression between plants grown in Italy and the UK could be used as markers of phytochemical quality and composition.

Development of Vacuum Hydrodistillation Technology in Citronella Oil Distillation (Cymbopogonnardus) as an Effort to Improve The Economy of the People of Blang Poroh Village, Lhokseumawe

Fragrant lemongrass oil is one of the products of non-timber forest products (HHBK) and is commercially obtained from the distillation of the leaves of the citronella plant (Cymbopogonnardus). Fragrant lemongrass leaves are one of the raw materials to obtain vegetable oil in the form of essential oils. Essential oils are the main components consisting of geraniol and citronellal arrangements. The essential oil extract process can be done by various methods, one of which is the Vacuum Distillation method. The Vacuum Distillation Method is carried out using a vacuum pump as a pressure guard and the boiling point of the distillation process does not exceed the temperature of the boiling point of water, which is 1000C, so that the oil produced is maintained purity. The Vacuum Hydrodistillation Process of citronella is carried out for 3, 5, and 7 hours with each treatment using raw materials of random and whole cut sizes. The essential oil products produced are analyzed in the form of yield, density, refractive index and oil composition analysis with GC-MS. The best essential oil results from citronella were obtained under operating conditions with random cut samples and a distillation time of 5 hours. Where the yield produced is 0.17% with a refractive index of 1.41570 and a density of 0.92735 gr / ml.

Geochemistry of the Albian to Upper Maastrichtian formations of the K1 oil well (East of the Côte d’Ivoire offshore basin): Depositional environment and implication of provenance

The studies were carried out on 93 samples of cuttings from the K1 oil well. These samples were processed using the Fluorescence Spectrometer (XRF) method. Chemical analyses contributed to the determination of depositional environments and origin of the sediments. Albian sediments deposited in an environment proximal to the continental characterize the MS1 mega-sequence. In contrast, the MS2 mega-sequence (Cenomanian to Maastrichtian) was deposited in a shallow to deep marine environment marked by a decrease in detrital flow. The ratio Ti/Y, with values below 0.017 in the MS1, means that the sediment source of the mega-sequence MS1would therefore be richer in phosphates, with a contribution from mafic volcanic rocks (rich in illite, iron and magnesium). In contrast to MS1, MS2 is characterized by ratio Ti/Y values above 0.017. This decrease in Yttrium content in this mega-sequence is consistent with Th/Al values below 1.588. This would suggest a richer source of titanium oxides, which could be rutile, sphene or anatase.

Inferring damage state and evolution with increasing stress using direct and coda wave velocity measurements in faulted and intact granite samples

SUMMARY A better understanding of damage accumulation before dynamic failure events in geological material is essential to improve seismic hazard assessment. Previous research has demonstrated the sensitivity of seismic velocities to variations in crack geometry, with established evidence indicating that initial crack closure induces rapid changes in velocity. Our study extends these findings by investigating velocity changes by applying coda wave interferometry (CWI). We use an array of 16 piezoceramic transducers to send and record ultrasonic pulses and to determine changes in seismic velocity on intact and faulted Westerly granite samples. Velocity changes are determined from CWI and direct phase arrivals. This study consists of three sets of experiments designed to characterize variations in seismic velocity under various initial and boundary conditions. The first set of experiments tracks velocity changes during hydrostatic compression from 2 and 191 MPa in intact Westerly granite samples. The second set of experiments focuses on saw-cut samples with different roughness and examines the effects of confining pressure increase from 2 to 120 MPa. The dynamic formation of a fracture and the preceding damage accumulation is the focus of the third type of experiment, during which we fractured an initially intact rock sample by increasing the differential stress up to 780 MPa while keeping the sample confined at 75 MPa. The tests show that: (i) The velocity change for rough saw cut samples suggests that the changes in bulk material properties have a more pronounced influence than fault surface apertures or roughness. (ii) Seismic velocities demonstrate higher sensitivity to damage accumulation under increasing differential stress than macroscopic measurements. Axial stress measured by an external load cell deviates from linearity around two-third through the experiment at a stress level of 290 MPa higher than during the initial drop in seismic velocities. (iii) Direct waves exhibit strong anisotropy with increasing differential stress and accumulating damage before rock fracture. Coda waves, on the other hand, effectively average over elastic wave propagation for both fast and slow directions, and the resulting velocity estimates show little evidence for anisotropy. The results demonstrate the sensitivity of seismic velocity to damage evolution at various boundary conditions and progressive microcrack generation with long lead times before dynamic fracture.

Assessment of kerogen types and source rock potential of Lower Jurassic successions in the Mandawa Basin, SE Tanzania

Variability in organic matter types and quality of source rock intervals across evolving rift-basins has been the focus of previous studies, which have shown that due to dynamic sedimentary regimes and water depths such source intervals occur sporadically and restricted to specific stratigraphic horizons. Such heterogeneous settings require detailed geochemical analysis to document variations in source quality. This study presents a comprehensive geochemical analysis of source rock intervals in Lower Jurassic successions (Mbuo, Nondwa and Mihambia Formations) in the Mandawa Basin, on-shore Tanzania, in order to constrain organic matter types and quality. Organic matter richness was measured by Total Organic Carbon (TOC) analysis, while quality and thermal maturity of organic matter was assessed by programmed pyrolysis, complemented by organic carbon isotope analysis (δ13Corg) of sediment samples collected from outcrops, cores, and cuttings samples. TOC and programmed pyrolysis datasets from existing literature were synthesized in this study to better understand organic matter quality and thermal maturity evolution on regional scale. These data were examined in relation to paleogeography to gain insight into the factors regulating the distribution of organic matter quality within the Mandawa Basin.Average TOC contents in Lower Jurassic sediments fluctuate from 0.31 to 4.83 wt% with an average of 1.4 wt%, whereas, kerogen yield (S2) and hydrogen index (HI) remain generally low, with values ranging from 0.01 to 8.6 (mg HC/g rock) with an average (0.92 mg HC/g rock) as well as from 2 to 233 (mg HC/g TOC) with an average of 46 (mg HC/g TOC), respectively. Organic matter is composed mainly of type III (gas prone) to IV (inert) kerogens with lesser admixture of type II-III kerogen (oil-gas prone), which have been deeply buried and undergone a wider range of thermal diagenesis, from early to overmature stage. The δ13Corg isotopic composition of organic matter is consistent with kerogen typing, indicating terrestrial organic matter with a heavier signature during sea level low stands. Upon marine incursions δ13Corg shifts to isotopically more depleted marine organic matter. This implies that the investigated source intervals have poor to fair source potential. Only a few intervals of limited thickness in the Upper Mbuo, Nondwa, and Mihambia Formations of the Mita Gamma-1 and East Lika-1 wells, as well as in the Lower Mbuo Formation in the Mbuo-1 well, have been locally enriched. The enrichment is attributed to periodic marine ingressions that have persisted since the Pliensbachian period and suggests the presence of oil generation potential.A comparison of TOC and programmed pyrolysis borehole data from this study to those compiled from literature in a paleogeographical context reveals high spatial variability. The southeastern and northwestern parts of the study area have the highest source potential, indicating high organic matter productivity in the dysoxic to anoxic water column, which promoted the preservation of organic matter. In contrast, the eastern and western parts generally show low source potential, indicating degraded organic matter and significant terrestrial influxes from emergent land that were deposited in shallow, mixed oxygenated water with low to moderate organic matter productivity.