Natural Samples Research Articles

Analysis of the modification of piping channels on kaolinitic clayey samples in the pinhole test

Dispersivity is a severe pathology that occurs mainly in clay soils and is usually catastrophic in geotechnical structures susceptible to this damage. Hundreds of dams worldwide have failed due to quality problems, mainly by piping in the body, foundation, spillway, culvert, and other peripheral structures. The pinhole test is currently considered the most accurate test for detecting the dispersivity of clay soils. However, it presents problems when objectively evaluating the dispersivity of a material due to the qualitative nature of the estimation of results. In particular, the methodology for determining turbidity has been identified. This document studies different piping paths in the sample, which a priori may be more realistic than the single path in the current test. A kaolinitic clay, widely studied through index and mineralogical tests, is used as the base material. Regarding the detection of dispersivity, a specialized test package was used to reduce the uncertainty of the results. Natural samples were analyzed using ASTM D4647-13. A modification of the pinhole test was proposed based on the imposition of additional artificial channels. The results revealed that this modification can make the test more realistic because when the dispersive front advances in the soil, it does not travel along a single path but instead looks for different erosive paths. The details of this assertion are discussed throughout the paper.

Abstract PO1-05-11: Efficacy of metformin as adjunctive therapy in patients with de novo metastatic breast cancer: a retrospective cohort study

Abstract Background: Metformin, an oral biguanide used for the treatment of type-2 diabetes mellitus (DM), has been shown in a considerable number of studies to have an anti-tumorigenic impact against breast cancer cells through several mechanisms,thereby improving breast cancer outcomes. However, the impact of metformin treatment on survival outcomes in patients with non-diabetic breast cancer is still under debate, with very few data available regarding metformin administration in de novo metastatic breast cancer (dnMBC). This study was conducted to investigate and evaluate the impact on survival outcomes of patients with dnMBC treated with metformin as adjunctive therapy at our institutes. Methods: All dnMBC women who received chemotherapy-based systemic therapy or combined with metformin administered orally in our hospitals between March 2007 and November 2016 were enrolled in the study. Data were retrospectively extracted from the patients’case records. Data were analyzed according the clinicopathological features and treatment outcomes. All specimens were rechecked for the purpose of the research. Overall survival (OS), as the study endpoint, was defined as the time from pathologically confirmed diagnosis to all-cause death or end of the follow-up time.Kaplan-Meier estimate was used to calculate the survival rates.The difference between metformin and non-metformin groups was compared by the log-rank method.Cox regression analysis (uni-and multivariate analysis) was used to assess the effect of variables on survival outcomes.Analyses were performed by Stata 17 software for windows version. Results: A total of 252 women with dnMBC were included with an average age of 54.41±11.61 years. Among them, 97 patients (including 11 DM patients) received chemotherapy-based systemic therapy plus oral administration of metformin 850-1000mg twice daily (metformin group), and 155 patients received chemotherapy-based systemic therapy (non-metformin group). There was no significant difference in body mass index, age, N-stage, P53 index, ER/PR status, HER-2 expression and initial metastatic sites between metformin group and non-metformin group. But there were differences in T-stage and Ki67 index between the two groups (Table 1). The median follow-up was 70 months.The median OS was 24 months.The 3-year and 5-year OS rates for all patients were 29.8% (95% CI:24.2% to 35.4%) and 11.6% (95% CI:7.5% to 16.7%),respectively; Log-rank test showed that the metformin group had a significant advantage over the non-metformin group in OS rates(p=0.0002).The 3-year and 5-year OS rates in the metformin group were 42.3% (95% CI:32.4% to 51.8%) and 21.2% (95% CI:12.8% to 31.1%), respectively; the same rates for non-metformin group were 21.9% (95% CI: 15.8% to 28.7%) and 5.6% (95% CI: 2.4% to 11.1%), respectively. Results of proportional hazards model, after adjustment for T-stage and Ki67 index, depicted an independent prognostic value of metformin use with multivariate hazard ratio of 0.61 (95% CI: 0.45 to 0.81) for OS compared to non-metformin group (p=0.001).No survival advantage was found for DM patients (0.59;95% CI:0.29 to 1.22; p=0.159). Conclusions: Our data support a favorable outcome for survival associated with metformin use in dnMBC patients. However, the retrospective nature and small sample size of the current study are major limitations to reliable conclusions about metformin's potential to improve OS in patients. Therefore, prospective evidence from phase-3 randomized controlled trials on the feasibility of metformin use in dnMBC is required before its routine use can be recommended. Keywords: Metformin; De novo metastatic breast cancer; Adjunctive therapy; Survival outcomes Citation Format: Ren Chongxi, Sun Jianna, Kong Lingjun, Hongjun Yu. Efficacy of metformin as adjunctive therapy in patients with de novo metastatic breast cancer: a retrospective cohort study [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO1-05-11.

A rapid procedure for isotopic purification of copper and nickel from seawater using an automated chromatography system

BackgroundTrace metals such as iron, nickel, copper, zinc, and cadmium (Fe, Ni, Cu, Zn, and Cd) are essential micronutrients (and sometimes toxins) for phytoplankton, and the analysis of trace-metal stable isotopes in seawater is a valuable tool for exploring the biogeochemical cycling of these elements in the ocean. However, the complex and often time-consuming chromatography process required to purify these elements from seawater has limited the number of trace-metal isotope samples which can be easily processed in biogeochemical studies. To facilitate the trace-metal stable isotope analysis, here, we describe a new rapid procedure that utilizes automated chromatography for extracting and purifying Ni and Cu from seawater for isotope analysis using a prepFAST-MC™ system (Elemental Scientific Inc.). ResultsWe have tested the matrix removal effectiveness, recoveries, and procedural blanks of the new purification procedure with satisfactory results. A nearly complete recovery of Ni and a quantitative recovery of Cu are achieved. The total procedural blanks are 0.33±0.24 ng for Ni and 0.42±0.18 ng for Cu, which is negligible for natural seawater samples. The new procedure cleanly separates Ni and Cu from key seawater matrix elements that may cause interferences during mass spectrometry analysis. When the new procedure was used to purify seawater samples for Ni and Cu stable isotope analysis by multi-collector ICP-MS, we achieved an overall uncertainty of 0.07‰ for δ60Ni and 0.09‰ for δ65Cu (2 SD). The new purification procedure was also tested using natural seawater samples from the South Pacific, for comparison of δ60Ni and δ65Cu achieved in the same samples purified by traditional hand columns. Both methods produced similar results, and the results from both methods are consistent with analyses of δ60Ni and δ65Cu from other ocean locations as reported by other laboratories. SignificanceThis study presents a new rapid procedure for seawater stable-metal isotope analysis by automating the chromatography step. We anticipate that the automated chromatography described here will facilitate the rapid and accurate analysis of seawater δ60Ni and δ65Cu in future studies, and may be adapted in the future to automate chromatographic purification of Fe, Zn, and Cd isotopes from seawater.

Detecting the invisible through DNA metabarcoding: The role of gelatinous taxa in the diet of two demersal Antarctic key stone fish species (Notothenioidei)

AbstractGelatinous zooplankton (GZP), i.e., ctenophores, cnidarian medusae, chaetognaths, appendicularians and salps, are considered climate change winners. This becomes particularly obvious in the Southern Ocean, which has undergone a significant shift from a krill‐based to a salp‐based ecosystem over the last decades. A better knowledge on the role of gelatinous invertebrates as prey is needed to predict the impact of such a gelatinous shift. Until recently, GZP was considered as a “trophic dead end”. However, their true importance in diets has remained unresolved due to the rapid digestion of their watery and soft tissues in predators' stomachs. In this study, we want to validate the paradigm shift from GZP being considered as “survival food” to be considered a “regular” prey item for two demersal fish species (Notothenia rossii and N. coriiceps) of Potter Cove, South Shetland Islands, using a multimarker (COI and 18S) metabarcoding approach. We found that GZP taxa commonly occurred in the diets of both species, represented by pelagic tunicates (appendicularians, salps), cnidarians, chaetognaths and ctenophores. Salps were the most abundant prey group, preyed upon by each individual of both species, reaching 98.7% relative read abundance for 18S. We recovered a wide range of different taxa in their diets, from primary producers to highly abundant invertebrates, thus the two nototheniid species can be regarded as “natural samplers” of the ecosystem in study. Finally, we want to point out the importance of multimarker metabarcoding approaches for broad ecological assessments, given the differential amplification and sequencing success of different markers for specific groups and the unequal taxonomic coverage of the reference databases. The output of each marker was highly complementary, since an important prey item such as salps, was only detected with 18S, while other taxa (e.g., Arthropoda) were represented with a higher taxonomic resolution with COI.

A facile electrochemical aptasensor for chloramphenicol detection based on synergistically photosensitization enhanced by SYBR Green I and MoS2

This study described the development of a photocatalytic electrochemical aptasensor for the purpose of detecting chloramphenicol (CAP) antibiotic residues in water by utilizing SYBR Green I (SG) and chemically exfoliated MoS2 (ce-MoS2) as synergistically signal-amplification platforms. The Au nanoparticles (AuNPs) were electrodeposited onto the surface of an indium tin oxide (ITO) electrode. After that, the thiolate-modified cDNA, also known as capture DNA, was combined with the aptamer. Subsequently, photosensitized SG molecules and ce-MoS2 nanomaterial were inserted into the groove of the resultant double-stranded DNA (dsDNA). The activation of the photocatalytic process upon exposure to light resulted in the generation of singlet oxygen. This singlet oxygen effectively splits the double-stranded DNA, resulting in a significant enhancement in the current of [Fe(CN)6]3-/4-. When the CAP was present, both SG molecules and ce-MoS2 broke away from the double-stranded DNA, which turned off the photosensitization response, leading to a significant decrease in the current of [Fe(CN)6]3-/4-. Under optimal conditions, the aptasensor exhibited a linear relationship between CAP and logarithmic concentrations from 20 to 1000 nM, with a detection limit (3σ) of 3.391 nM. The aptasensor also demonstrated good selectivity towards CAP in the presence of interfering antibiotics such as tetracycline, streptomycin, levofloxacin, ciprofloxacin, and sulfadimethoxine. Additionally, the results obtained from the analysis of natural water samples using the proposed aptasensor were consistent with the findings acquired through the use of a liquid chromatograph-mass spectrometer. Therefore, with its simplicity and high sensitivity, this biosensor can potentially detect alternative antibiotics in environmental water samples by replacing the aptamers based on photosensitization.

Detection of gunshot residue by flash-pulse and long-pulse infrared thermography

Detection of gunshot residues (GSR) in a bullet hole area is one of the forensic investigations aiding in the reconstruction of crime scenes. Traditionally, chromogenic methods based on chemical exposure or microscopic/spectroscopic methods are used for this purpose. In this study, we explore the applicability of active excitation infrared thermography methods for GSR detection in the bullet hole area on fabric samples. A standard 9 mm full metal jacket ammunition with a nickel-plated shell and natural cotton fabric samples were used for experiments in this study. The applicability of active thermography methods based on two different light/heat excitation sources to detect the GSR was investigated. Flash-pulse and long-pulse thermography were compared through an experimental investigation. We evaluated the effectiveness of various thermographic data processing methods, including background subtraction, temperature derivative analysis, Fourier transform phase analysis, principal component analysis, and higher-order statistics for GSR evaluation. Our findings demonstrate that flash-pulse thermography and kurtosis analysis yield the highest contrast-to-noise ratio (CNR) and produce sharp, clear images of GSR, making it the optimal method for thermographic GSR detection. Our study indicates that even though the GSR particles are tiny, they can produce sufficient contrast to be detected by the thermographic methods if appropriate experimental and post-processing procedures are used. Thus, these methods could complement GSR detection as they are non-destructive and offer rapid inspection.

Unraveling the relationship between the mineralogical characteristics and lithium storage performance of natural graphite anode materials

Anode materials play critical role in cycling life of lithium-ion batteries in practical applications such as electric vehicles (EVs), portable electronic devices, and large-scale power grids. Natural graphite is one of the most successful anodes for commercial lithium-ion batteries due to its high theoretical capacity and low cost and low operating voltage. The mineralogical properties of graphite minerals have an important effect on the electrochemical performance of graphite anode, while their relationship remains ambiguous. In this work, natural graphite samples from four main graphite mining areas in China were selected as the research object, and their mineralogical characteristics were characterized by XRD, SEM, Raman, ICP, SEM, FIB, BET and other test methods. The properties of crystallinity, morphology, surface/phase defects, impurities, and specific surface area of graphite were studied. The results show that the cyclic stability of graphite is mainly affected by bulk defects and crystallinity, and the initial coulombic efficiency is mainly affected by surface defects and specific surface area. Graphite samples with appropriate surface defects, fewer volume defects, appropriate crystallinity, and small specific surface area have better electrochemical performance. It is hoped that this work should guide the manufacture and modification of the natural graphite anodes and promote its wider application in lithium-ion batteries.

Are minimally verbal autistic children's modality and form of communication associated with parent responsivity?

Prior work examined how minimally verbal (MV) children with autism used their gestural communication during social interactions. However, interactions are exchanges between social partners. Examining parent-child social interactions is critically important given the influence of parent responsivity on children's communicative development. Specifically, parent responses that are semantically contingent to the child's communication plays an important role in further shaping children's language learning. This study examines whether MV autistic children's (N = 47; 48-95 months; 10 females) modality and form of communication are associated with parent responsivity during an in-home parent-child interaction (PCI). The PCI was collected using natural language sampling methods and coded for child modality and form of communication and parent responses. Findings from Kruskal-Wallis H tests revealed that there was no significant difference in parent semantically contingent responses based on child communication modality (spoken language, gesture, gesture-speech combinations, and AAC) and form of communication (precise vs. imprecise). Findings highlight the importance of examining multiple modalities and forms of communication in MV children with autism to obtain a more comprehensive understanding of their communication abilities; and underscore the inclusion of interactionist models of communication to examine children's input on parent responses in further shaping language learning experiences.

Establishing freshwater sediment sample pretreatment methods for monitoring microplastics and its challenges

Microplastics (MPs) have been detected in various environmental matrices, drinking water, and food, and their presence is an ecological and human health concern. Most research on MPs has focused solely on their detection and analysis. However, sample pretreatment methods are critical for accurate MP analysis and must be properly established. In particular, freshwater sediment contains more impurities than other environment samples, thus requiring more elaborate sample pretreatment. Therefore, research on this media and corresponding pretreatment needs to be performed. Herein, we present a sample pretreatment method for analyzing MPs in freshwater sediments. Detailed factors in arriving at this pretreatment process were evaluated and discussed. Using this established pretreatment method, a total average recovery of six types of standard MPs (HDPE, LDPE, PS, PP, PET, and PVC) for sizes of 100 µm, 20–100 µm, and 1–20 µm was 94.0 %, 90.2 %, and 82.5 %, respectively. After recovery validation, a modular pretreatment device was developed and combined with the established pretreatment method. The developed device performs density separation and organic matter removal, resulting in about 80 % recovery of standard MPs. In addition, natural freshwater sediment samples were prepared using an established pretreatment method, and MPs in streams were analyzed using FTIR, TED-GC–MS, and Pyr-GC–MS. The device affords a low-cost, simple, efficient tool for sample pretreatment steps and easy MP recovery. Thus, it has great potential to simplify sample pretreatment steps for easy MP monitoring, especially for freshwater sediment samples.

Micro-sample Nd isotopic measurement on reference rock powders via the thermal ionization mass spectrometer Nd+ mode

The Sm-Nd isotopic system has been broadly utilized for dating and tracing in earth and planetary sciences. However, low Nd+ ionization efficiency permanently hinders precise and accurate measurements on small amounts of Nd samples. So far, isotopic measurement of micro-amount Nd sample via thermal ionization mass spectrometry (TIMS) Nd+ mode was mostly performed on Nd reference solutions, but less on natural rock or mineral samples. In the present study, analytical procedures to measure isotopic composition via the TIMS Nd+ mode were designed for natural rock powders by using 1 to 5 ng pure Nd. The analytical technique was refined through low-blank sample digestion, small-column chemistry for Nd extraction from matrix elements, loading Nd using purified H3PO4 solution, and careful heating of filaments before data acquisition. Measurements on small Nd amounts (1ng to 5 ng) of either the JNdi-1 reference solution or four reference rock powders yielded satisfactory results of 143Nd/144Nd value with respect to precision and accuracy. The analytical results agree well with the recommendation values of the reference materials within analytical errors and the internal precision is better than ±0.005% (2RSE). When using 1 ng or 2 ng Nd amounts, 144Nd ion flow can remain stable in a signal intensity of >100 mV, and without the assistance of an additional ionization enhancer. Therefore, the analytical procedure, featured by low procedural blank (about 10-22 pg), high Nd+ ionization efficiency, and easy operation, has broad prospects for the application of Nd isotope in single-grain minerals or micro-samples.

Impact mechanism of active nanofluid on oil–water two-phase seepage during and after fracturing fluid invasion in tight oil reservoirs

Due to damage caused by fracturing fluid invasion, tight oil reservoirs exhibit slow post-hydraulic fracturing production recovery and low productivity. This study investigates the impact of a nanoclay-based active agent system on oil–water two-phase flow during and after fracturing fluid invasion, emphasizing its potential for enhancing recovery in tight oil reservoirs. Laboratory experiments using crude oil and natural core samples analyze the mechanism of how nanofluids affect oil–water distribution and flow characteristics during fracturing fluid invasion and oil recovery stages. Results show that nanofluids rapidly disrupt the emulsified state of “water-in-oil” emulsions, reducing emulsion viscosity by 84.19% and oil–water interfacial tension by two orders of magnitude, facilitating oil droplet dispersion and deformation and altering the wettability of oil-wet rock surfaces to aid crude oil detachment. Nanofluids increase the accessible volume of the water phase in pores and throats, enlarging flow paths for fracturing fluid flowback and oil recovery. The oil recovery process post-fracturing fluid invasion is delineated into three stages: substantial fracturing fluid flowback in the first stage, with nanofluids reducing the fluid return rate by 11.08% upon crude oil breakthrough; emulsion droplets occupying pores and throats in the second stage, with nanofluids reducing additional resistance during emulsion flow; and continuous oil production in the third stage, with nanofluids consistently and stably altering rock surface wettability to reduce invaded rock matrix resistance to oil flow. The findings of this study hold potential value in mitigating damage from fracturing fluid invasion in tight oil reservoirs.

Calibration of buried NaI(Tl) scintillator detectors for natural radionuclide measurement based on Monte Carlo modelling

Measurements of naturally occurring concentrations of 40K, and of the decay series of 238U and 232Th, are of interest in the earth sciences in general, and in particular, scintillator-based gamma spectrometers can be used for the low cost determination of burial dose rates in natural geological samples. We are currently developing a robust, portable, wireless detector specifically intended for field measurement of natural radionuclide concentrations and hence, the calculation of dose rates. One of the challenges in developing and applying such an instrument is reliable calibration. Most calibrations of field instruments depend on access to non-finite matrices of known K, U, Th activity concentrations, in either a 4π or 2π geometry; these are only available at a few facilities around the world. Here we investigate an alternative approach, based on the measurement of small samples containing well-known activity concentrations of only K or U or Th, and Monte-Carlo radiation transport modelling to convert the observed spectra into those expected from specific activity concentrations in a non-finite 4π geometry. We first validate our modelling procedure by simulating these observed spectra. The non-finite matrix calibration spectra are then predicted, and least-squares fitted to the spectrum observed at the centre of a 1 m3 of granite chips; the resulting predicted U, Th and K activity concentrations are compared with independently known values.

Elemental quantitation and evaluation of hydrocarbon in shale using fiber-optic laser induced breakdown spectroscopy

To meet the demands of in situ analysis, a fiber-optic laser-induced breakdown spectroscopy (FO-LIBS) system was established to predict the elemental concentrations and pyrolytic parameters. The key parameters, including pulse energy, gate delay, type of surrounding gas, and flow rate of gas, were optimized to improve the signal-to-noise ratio of the spectral lines, and the evolution characteristics of the plasma morphology in different gas atmospheres were investigated. Under the optimized experimental conditions, C, H, Si, Ca, Fe, and Mg were calibrated using pellet samples based on partial least squares regression, and the average relative prediction error of the natural samples was lower than 10%. In addition, the support vector regression method was utilized to predict pyrolytic parameters such as TOC, Pg, and Tmax with the R2 of all calibration curves being higher than 0.97. The abundance and generation potential of hydrocarbons were evaluated using the predicted TOC and Pg, and Tmax could contribute to the thermal maturity of the kerogen.

Application of ATONA Amplifiers to the Measurement of Uranium Isotopic Ratios by Thermal Ionization Mass Spectrometry.

Uranium isotopic composition can provide valuable information about the history and provenance of a nuclear material; therefore, uranium isotopic analyses are frequently made in the nuclear forensics, safeguards, and environmental monitoring communities. These measurements have always presented challenges due to the extreme variability in the relative abundance between the major (235U, 238U) and minor (233U, 234U, 236U) isotopes of uranium. The recently developed ATONA (Atto- to Nano-Amp) amplification system paired with Faraday cup detectors has a large dynamic range and low noise floor making it ideal for measuring uranium isotopic ratios in materials of both natural and anthropogenic origin. A wide variety of certified reference materials were analyzed to investigate the utility of the ATONA amplification system for determining uranium isotopic composition in samples ranging from depleted to highly enriched. The ATONA amplifiers provide nearly an order of magnitude improvement in external reproducibility over 1011 Ω amplifiers when measuring the minor 234U/238U ratio in isotopically natural and depleted samples and when paired with a secondary electron multiplier can measure very low relative abundance uranium isotopes (i.e., 236U).

Preparation of a sustainable magnetic sorbent for the extraction and preconcentration of progestogens in natural water samples

A film composed of agarose and graphene (G) and magnetic nanoparticles (G-MNPs) is proposed as a sorbent for the extraction and determination of medroxyprogesterone (MED), levonorgestrel (LEV), norethisterone (NOR) and progesterone (PRO) in natural water samples. Both the preparation of the film and the extraction procedure were optimized. The optimal extraction parameters were as follows: isopropyl alcohol as activation solvent, sample pH value of 3.0, extraction time of 30 min, 1.00 mL of acetonitrile as eluent, elution time of 5 min and sample volume of 100.00 mL. HPLC with photodiode array detector was used for the separation and determination. The method presented a linear range between 2.50 and 75.0 μg L−1 for all analytes, and the LODs were between 1.40 and 1.80 μg L−1. The method was applied to natural water samples, obtaining satisfactory recovery values (75–111 %). In conclusion, for the immobilization of the G-MNPs, agarose was used, which is a non-toxic, renewable and biodegradable material. The G-MNPs-agarose film was reused up to 70 times, without losing its extraction capacity significantly and presenting excellent sorbent properties, which allow the extraction and preconcentration of the progestogens under study.

Stability Analysis of Feed Gas Based on Pressure using Gas Chromatography at PT Badak NGL

As one of the LNG processing companies in Indonesia, Badak NGL plays an important role in product QA and QC. Laboratory and Environment Control PT Badak NGL obtained ISO 17025 as a testing and calibration laboratory. In clause 7.7 of ISO 17025, stated that each laboratory is required to improve competence, one of which is by holding interlaboratory meetings. Currently, PT Badak NGL is participating in the implementation of the Inter Laboratory Meeting (ILM) in East Kalimantan. In the implementation of the ILM 112th and 113th in 2022, several laboratories provide outlier results in natural gas sample testing. Various factors affect the results of natural gas sample testing, one of them is the sample pressure. This research aims to determine the minimum pressure limit in testing feed gas samples. The test is carried out by designing a series of two cylinders to test the repeatability value. The sampling process is based on GPA 2166 and the measurement of repeatability values is based on GPA 2261. This method is effective for determining the limit of repeatability values as a reference for the minimum sample pressure before being injected into Gas Chromatography.

Comparison of PetrifilmTM AC and Pour plate techniques used for the heterotrophic aerobic bacterial count in water.

Heterotrophic bacteria (HPC) are commonly found in water samples. While these bacterial counts do not necessarily indicate a health hazard, high counts provide a good indication of the efficiency of water disinfection and integrity of distribution systems. The aim of this study was to compare the PetrifimTM AC method to the Pour Plate technique for the testing of HPC in water samples. Artificially contaminated (192 samples) and natural water samples (25) were processed using two methods. Both methods accurately detected high, medium and low counts of HPC, producing average Z scores between -2 and+2. Paired-wise student t-test and correlation coefficient showed nonsignificant differences between the results of two methods. Acceptable repeatability and reproducibility was obtained using both the methods. Uncertainty of measurement for PetrifilmTM AC and Pour Plate method was found to be 2.9% and 5.4% respectively. PetrifilmTM AC proved to be robust at 33°C and 37°C. In conclusion, PetrifimTM AC, which is easy to process, read and less time consuming, proved to be comparable to the conventional Pour Plate method in establishing HPC in water. In addition, PetrifimTM AC requires less space for the processing and incubation, generate small volume of waste for disposal and requires no equipment, except for the incubator.

Assessing the feasibility of laser induced breakdown spectroscopy for detecting nitrogen in martian surface sediments

Despite the detection of fixed nitrogen in meteorites and directly on Mars' surface, the abundance and distribution of nitrogen sequestered in the martian crust remains unknown. Given that nitrogen is a bioessential element that is required for the synthesis of amino acids, nucleic acids, and other organic molecules vital for life, this gap in knowledge is one of the most important challenges in constraining martian habitability. Laser-induced breakdown spectroscopy (LIBS) has the capability to detect N in natural rock samples and is available as a stand-off survey instrument on multiple currently active Mars rovers, creating an immediate opportunity to map the stratigraphic distribution of N within diverse depositional settings. However, little has been published regarding the detection of N with LIBS.To lay a foundation for N detection on Mars using LIBS, we synthesized a comprehensive suite of samples with variable amounts of nitrogen (as nitrate or ammonium) in either a Mars regolith simulant or a clay matrix. We present baseline spectra of N emission in Mars-relevant matrices and identify spectral interferences. Our results indicate that 17 diagnostic N emission lines are reliably detectable from mineral-bound N against a basaltic background, but only four lines exhibit sufficient sensitivity to be detected across a range of N concentrations and within all tested matrices. To elucidate optimized strategies for quantification, we present an iterative series of PLS models. We find that prediction accuracy is improved by restricting the compositional range of the training set, normalizing the data, subtracting baseline continuum emission, and simultaneously modeling the emission behaviour of multiple diagnostic N lines at once. We observe that the prediction uncertainty increases (worsens) from 8.4% to 29.9% if models are used to predict N in samples with a dissimilar matrix than those used during training, suggesting poor generalizability outside the training range. Consequently, future work should focus on developing a larger, more diverse training set that encompasses the range of N concentrations and phases expected to be encountered on Mars, which may be used to train generalizable models. Overall, this work demonstrates that LIBS is a promising tool for determining the abundance of N sequestered in martian surface materials and lays a foundation for future development.

Interpretable knowledge-guided framework for modeling reservoir water-sensitivity damage based on Light Gradient Boosting Machine using Bayesian optimization and hybrid feature mining

Reservoir water sensitivity damage significantly contributes to production declines in low-permeability oil and gas fields. An accurate and rapid assessment of water sensitivity is essential for effective mitigation or prevention strategies. Facing the intricate challenge of predicting high-dimensional water sensitivity damage, this study leverages trends in intelligent drilling and completion technologies. It adopts a Knowledge-guided, Bayesian Optimization-enhanced Light Gradient Boosting Machine (KBO-LightGBM) for modeling, augmented by Multiple Imputation by Chained Equations and Synthetic Minority Over-sampling Technique (MICE-SMOTE) to address missing and unbalanced data issues in oil and gas fields, thereby enhancing the scientific efficacy of data processing. The framework's precision and practicality were confirmed using data from 270 natural core samples across 15 oil fields. Findings include a correlation coefficient of 0.9679 on the test set, a root mean square error of 3.4797, and a mean absolute percentage error of 4.0936%. Interpretability analysis identified formation water mineralization, burial depth, feldspar content, and initial porosity as the predominant factors affecting water sensitivity. This research distinguishes itself with a broader dataset, covering 15 parameters of formation fluids and rock components. Weighting factor αDK and scale βDK were designed to integrate empirical correlations into LightGBM's loss function, theoretically mitigating model overfitting. Hence, the intelligent framework proposed herein accurately predicts reservoir water sensitivity damage, aiding in the development of reservoir damage control strategies.

Real-time coded measures in natural language samples capture change over time in minimally verbal autistic children.

Prior research supports the use of natural language sampling (NLS) to assess the rate of speech utterances (URate) and the rate of conversational turns (CTRate) in minimally verbal (MV) autistic children. Bypassing time-consuming transcription, previous work demonstrated the ability to derive URate and CTRate using real-time coding methods and provided support for their strong psychometric properties. (1) Unexplored is how URate and CTRate using real-time coding methods capture change over time and (2) whether specific child factors predict changes in URate and CTRate in 50 MV autistic children (40 males; M = 75.54, SD = 16.45 (age in months)). A NLS was collected at Time 1 (T1) and Time 2 (T2) (4.5 months between T1 and T2) and coding was conducted in ELAN Linguistic Annotator software using a real-time coding approach to derive URate and CTRate. Findings from paired samples Wilcoxon tests revealed a significant increase in child URate (not examiner URate) and child and examiner CTRate from T1 to T2. Child chronological age, Mullen expressive language age equivalent scores, and URate and CTRate at T1 were predictive of URate and CTRate at T2. Findings support using NLS-derived real-time coded measures of URate and CTRate to efficiently capture change over time in MV autistic children. Identifying child factors that predict changes in URate and CTRate can help in the tailoring of goals to children's individual needs and strengths.