Individual Probes Research Articles

Rutile-phase Sn-Ti Mixed Oxides as Acid Catalysts for the Condensation of C2-C3 Oxygenated Compounds in Water.

The design of new cost-effective and water-resistant acid catalysts is crucial for valorizingaqueous side-streams to increase the efficiency and competitiveness of bio-refineries in a sustainable way. In this work, Sn-Ti mixed oxides are prepared via a green and scalable co-precipitation method. This synthesis procedure allows obtaining homogeneous rutile-phase Sn-Ti mixed oxides with enhanced textural properties and a higher amount of Lewis acid sites. More importantly, the catalytic behavior of these Sn-Ti mixed oxides is investigated by using an aqueous mixture of C2-C3 representative oxygenated compounds, closer to real industrial conditions and differing from usual individual probe molecules studies performed even in the absence of water. Catalytic experiments combined and correlated with spectroscopic measurements (i.e., XRD, TEM, FT-IR with pyridine adsorption-desorption and N2 adsorption) are performed to better understand the properties of different Sn-Ti catalysts. These materials show promising results in the condensation of light oxygenated compounds present in aqueous fractions. Homogeneous and robust rutile-phase structures with inherent hydrophobic characteristics turn these Sn-Ti materials into active and highly resistant catalysts capable to transform these low-value oxygenated compounds into a mixture of hydrocarbons and aromatics useful for blending with automotive fuels, especially under complex acidic aqueous environments and moderate process conditions.

Safety and Effectiveness of Triple-Antenna Hepatic Microwave Ablation

Microwave ablation is becoming a standard procedure for treating tumors based on heat generation, causing an elevation in the tissue temperature level from 50 to 60 °C, causing tissue death. Microwave ablation is associated with uniform cell killing within ablation zones, multiple-antenna capability, low complication rates, and long-term survival. Several reports have demonstrated that multiple-antenna microwave ablation is a promising strategy for safely, rapidly, and effectively treating large tumors. The key advantage of multi-antenna tumor microwave ablation is the creation of a large, well-defined ablation zone without excessively long treatment times or high power that can damage healthy tissue. The strategic positioning of multiple probes provides a fully ablated volume, even in regions where individual probe damage is incomplete. Accurate modeling of the complex thermal and electromagnetic behaviors of tissue is critical for optimizing microwave ablation because material parameters and tissue responses can change significantly during the procedure. In the case of multi-antenna microwave ablation, the calculation complexity increases significantly, requiring significant computational resources and time. This study aimed to evaluate the efficacy and safety of liver percutaneous microwave ablation using the simultaneous activation of three antennas for the treatment of lesions larger than 3 cm. Based on the known results from a single-probe setup, researchers can estimate and evaluate various spatial configurations of the three-probe array to identify the optimal arrangement. Due to the synergistic effects of the combined radiation from the three antennas, the resulting ablation zone can be significantly larger, leading to better outcomes in terms of treatment time and effectiveness. The obtained results revealed that volumetric damage and the amount of damaged healthy tissue are smaller for a three-antenna configuration than for microwave ablation using a single-antenna and two-antenna configurations.

Discrepancies in readouts between Infinium MethylationEPIC v2.0 and v1.0 reflected in DNA methylation-based tools: implications and considerations for human population epigenetic studies.

The recently launched DNA methylation profiling platform, Illumina MethylationEPIC BeadChip Infinium microarray v2.0 (EPICv2), is highly correlated with measurements obtained from its predecessor MethylationEPIC BeadChip Infinium microarray v1.0 (EPICv1). However, the concordance between the two versions in the context of DNA methylation-based tools, including cell type deconvolution algorithms, epigenetic clocks, and inflammation and lifestyle biomarkers has not yet been investigated. To address this, we profiled DNA methylation on both EPIC versions using matched venous blood samples from individuals spanning early to late adulthood across four cohorts. Within each cohort, samples primarily clustered by the EPIC version they were measured on. High concordance between EPIC versions at the array level, but variable concordance at the individual probe level was noted. Significant differences between versions in estimates from DNA methylation-based tools were observed, irrespective of the normalization method, with some nuanced differences across cohorts and tools. Adjusting for EPIC version or calculating estimates separately for each version largely mitigated these version-specific discordances. Our work illustrates the importance of accounting for EPIC version differences in research scenarios, especially in meta-analyses and longitudinal studies, when samples profiled across different versions are harmonized. Alongside DNA methylation-based tools, our observations also have implications in interpretation of epigenome-wide association studies (EWAS) findings, when results obtained from one version are compared to another, particularly for probes that are poorly concordant between versions.

Contact and bulk rectification effects in ferromagnetic resonance experiments

We present an experimental study of the spin rectification effects produced by ferromagnetic resonance in a NiFe wire. A system of four independent nonmagnetic contact probes was used to supply both rf and dc currents to the wire and to measure dc voltages at different locations in the wire. The rf current drives the ferromagnet’s magnetization into resonance and produces a dc photovoltage which results from the rectification of rf current in the ferromagnet with oscillating magnetization. Our 4-probe system provided a means to detect the photovoltage and separate contributions from the ferromagnet/nonmagnet contacts and the bulk of the ferromagnet. The contact photovoltage was found to increase approximately linearly with the dc bias applied to the wire. In contrast, the bulk contribution was found to be almost independent of the dc bias. By tuning properties of individual contact probes we were able to change the magnitude of the contact photovoltage and even reverse its sign. Our results highlight the different contributions to photovoltage and the importance of contact properties/nonlinearities for rectification effects in spintronic devices.

A high-density 1,024-channel probe for brain-wide recordings in non-human primates.

Large-scale neural population recordings with single-cell resolution across the primate brain remain challenging. Here we introduce the Neuroscroll probe that isolates single neuronal activities simultaneously from 1,024 densely spaced channels that are flexibly distributed across the shank of the probe. The Neuroscroll probe length is easily tunable for individual probes from 10 mm to 90 mm, covering the brain size of non-human primates and humans, and the probes remain intact and functional after repeated bending deformations. The Neuroscroll probes provided reliable recordings from large neural populations with high chronic stability up to 105 weeks in rats. Recording with each Neuroscroll probe yielded hundreds of well-isolated single units simultaneously from multiple brain regions distributed across the entire depth of the rhesus macaque brain. With the thousand simultaneously recorded channels, unprecedented probe length, excellent mechanical stability and flexible recording site distribution, the Neuroscroll probes enable a wide range of new experimental paradigms in system neuroscience studies with great versatility.

Development of a fixed Langmuir probe system for newly installed tungsten monoblock lower divertors in KSTAR

A fixed Langmuir probe system for newly installed tungsten monoblock lower divertors in KSTAR is developed. The probe structure is designed to effectively cooled via divertor coolant using inclined contact surfaces between the probe components. The probe body is tapered, narrowing up towards the divertor surface to enhance thermal contact conductance through mechanical forces exerted by the probe-divertor assembly. The probe structure is designed for easy replacement of a probe tip in the event of its damage and to accommodate different shapes of the tip. Currently, all the installed probe tips have 16° of inclination, i.e., one-sided rooftop shape, with respect to the surrounding divertor surface protruding 1.0 mm from the divertor surface. An individual probe system occupies two mono-blocks along the direction of the coolant channel. A single divertor cassette can accommodate 52 probes having a nominal poloidal spatial resolution of 12 mm. In the newly installed KSTAR divertor system, a total of 104 probes are installed at two toroidal locations. Thermal analysis on the probe structure indicates that the one-sided rooftop-shaped probe tips can withstand a localized heat flux of 10 MW/m2 for 2 s and 5 MW/m2 for steady-state operation. Experiments with a probe-divertor mockup are conducted in a linear plasma device under a magnetic field (|B|<360 G) and steady-state plasmas of a density of the order of 1011 cm−3. Possible analysis models for the I–V characteristics are discussed with practical applications to the measured data from KSTAR.

ICM-SHOX. I. Methodology Overview and Discovery of a Gas–Dark Matter Velocity Decoupling in the MACS J0018.5+1626 Merger

Galaxy cluster mergers are rich sources of information to test cluster astrophysics and cosmology. However, cluster mergers produce complex projected signals that are difficult to interpret physically from individual observational probes. Multi-probe constraints on the gas and dark matter (DM) cluster components are necessary to infer merger parameters that are otherwise degenerate. We present Improved Constraints on Mergers with SZ, Hydrodynamical simulations, Optical, and X-ray (ICM-SHOX), a systematic framework to jointly infer multiple merger parameters quantitatively via a pipeline that directly compares a novel combination of multi-probe observables to mock observables derived from hydrodynamical simulations. We report a first application of the ICM-SHOX pipeline to MACS J0018.5+1626, wherein we systematically examine simulated snapshots characterized by a wide range of initial parameters to constrain the MACS J0018.5+1626 merger geometry. We constrain the epoch of MACS J0018.5+1626 to the range 0–60 Myr post-pericenter passage, and the viewing angle is inclined ≈27°–40° from the merger axis. We obtain constraints for the impact parameter (≲250 kpc), mass ratio (≈1.5–3.0), and initial relative velocity when the clusters are separated by 3 Mpc (≈1700–3000 km s−1). The primary and secondary clusters initially (at 3 Mpc) have gas distributions that are moderately and strongly disturbed, respectively. We discover a velocity space decoupling of the DM and gas distributions in MACS J0018.5+1626, traced by cluster-member galaxy velocities and the kinematic Sunyaev–Zel'dovich effect, respectively. Our simulations indicate this decoupling is dependent on the different collisional properties of the two distributions for particular merger epochs, geometries, and viewing angles.

Research and application of a flexible measuring array for deep displacement of landslides

Abstract. The multidimensional and multi-sliding surface measurement of deep-seated displacement on landslides poses a significant technical challenge in landslide monitoring and early warning. The fixed-borehole inclinometer serves as an important measurement method based on drilling for this purpose. In this study, a novel flexible measurement array for deep-seated landslide displacement and its installation and measurement processes were developed, enabling higher accuracy in full-hole multidimensional deformation measurement. The measurement array consists of individual measurement probes as basic units, connected in series through coaxial cables and high-pressure rubber hoses, forming a flexible measurement array. Each probe is equipped with acceleration and magnetic field sensors, allowing for the measurement of borehole inclination and azimuth angles and providing a more comprehensive understanding of the deformation of deep-seated landslides. This flexible measurement array resolves the limitations of traditional fixed inclinometers, such as limited probe quantity or inaccurate installation positions that fail to reflect the deformation trend of the landslide body. Moreover, it eliminates the need for auxiliary installation accessories like pulleys and inclinometer pipes, simplifying the mechanical structure and installation process, which represents an advancement in methodology and an improvement in measurement techniques. This array provides a more comprehensive and improved monitoring tool for disaster prevention and mitigation, thereby enhancing the level of geological hazard monitoring and early warning technology.

Chemical bond reorganization in intramolecular proton transfer revealed by ultrafast X-ray photoelectron spectroscopy

Time-resolved X-ray photoelectron spectroscopy (TR-XPS) is used in a simulation study to monitor the excited state intramolecular proton transfer between oxygen and nitrogen atoms in 2-(iminomethyl)phenol. Real-time monitoring of the chemical bond breaking and forming processes is obtained through the time evolution of excited-state chemical shifts. By employing individual atomic probes of the proton donor and acceptor atoms, we predict distinct signals with opposite chemical shifts of the donor and acceptor groups during proton transfer. Details of the ultrafast bond breaking and forming dynamics are revealed by extending the classical electron spectroscopy chemical analysis to real time. Through a comparison with simulated time-resolved photoelectron spectroscopy at the valence level, the distinct advantage of TR-XPS is demonstrated thanks to its atom specificity.

Agora: Multicomponent simulation for cross-survey science

ABSTRACT Next-generation cosmological surveys will observe large portions of the sky, with significant overlap between them. Multi-wavelength observations will enable us to analyse the same large-scale structure from different angles using a variety of tracers and astrophysical effects. The complex interplay between these observables calls for a model that can accurately and coherently describe their collective behaviour, posing a challenge that can only be met through the use of simulations. In this work, a suite of simulated extragalactic skies is presented, including maps and/or catalogues of cosmic microwave background (CMB) lensing, thermal and kinetic Sunyaev–Zel’dovich (tSZ/kSZ) effects, cosmic infrared background (CIB), radio sources, galaxy overdensity and galaxy weak lensing. Each of these probes is implemented in the lightcone using halo catalogues and/or particles from the Multidark-Planck2 ($\small {MDPL2}$) N-body simulation, and the modelling is calibrated using hydrodynamic simulations and publicly available data. The auto and cross-spectra of the individual probes, as well as the cross-spectra between the observables, are shown to be consistent with theoretical models and measurements from data. The simulation is shown to have a wide range of applications, including forecasting, pipeline testing, and evaluating astrophysical biases in cross-correlation measurements. It is further demonstrated that the simulation products produced in this work have sufficient accuracy to recover the input cosmology when subjected to a full cosmological analysis and are ready for application in real-world analyses for ongoing and future surveys. The simulation products presented in this work can be accessed at: https://yomori.github.io/agora/index.html.

Gold nanoparticles-based colorimetric method for the rapid and sensitive detection of sour rot in onions

Onion (Allium cepa L.) is a major vegetable used in food preparation. It can also act as a medicinal compound for many diseases. However, various plant diseases, including sour rot, caused by the bacterium Burkholderia cepacia, is a post-harvest disease that can cause significant economic losses in onions and are considered a major threat to the onion industry. This study was performed to compare two methods for detecting sour rot: multiplex PCR and colorimetry with gold nanoparticles probe. Multiplex PCR used, primers designed for RecA, APZ15-03995 and APZ15-27735 genes of B. cepacia, and the results showed 100% specificity and sensitivity of 74.4 × 10−4 ng/μL of genomic DNA. Colorimetry with gold nanoparticles probe was performed using individual gene probes or a combination of three gene probes as a multi-colorimetric assay. Results showed 100% specificity and sensitivity of 74.4 × 10−8 ng/μL of genomic DNA in presence of the three probes. The results showed that both methods are specific and sensitive enough to detect B. cepacia. However, the use of gold nanoparticles is a more suitable option due to its high specificity and sensitivity and shorter time compared to multiplex PCR. Consequently, accurate and timely molecular identification of onion rot helps reduction of post-harvest losses and prevent the spread of secondary bacteria in storage.

Abstract 2935: NGS panel customization for comprehensive genomic profiling

Abstract Introduction: We have developed a custom SureSelect Cancer design pipeline for the creation of target enrichment gene panels for comprehensive profiling of single nucleotide variations (SNP/INDEL), gene-level copy number variations (CNV), and DNA translocations (TL) as well as content for measuring of microsatellite instability (MSI) and tumor mutational burden (TMB). Methods: The performance of individual probes was measured for the 679-gene SureSelect Cancer CGP panel and the information used to generate a reference database. When creating a new design, the gene list is cross-referenced with the database and when applicable, the probe information is applied to the new design. If genes are included in the custom design that are not present in the database, a second design algorithm selects the optimal probe based on its sequence characteristics (% GC, homology, etc.). Content is selected based on the biomarker to be measured and can be defined based on gene name (SNV/indel and CNV) or genomic coordinates (SNV/indel, TL). Pre-defined content for MSI measurement can be added to any design to cover 288 microsatellite sites. The performance of these sites in determining MSI status was demonstrated by comparing to the MSI-PCR reference method. To assess the performance of the design methodology, designs of various sizes (50 to 650+ genes) and content type were generated and assayed on reference samples and FFPE with known biomarkers. Sequencing metrics were evaluated for capture specificity and coverage of the target regions. Results: The design methodology allowed for sub-selection of content present in the 679-gene SureSelect Cancer CGP assay as well as addition of de-novo content. The design algorithm uses empirical data on probe performance to provide robust and reproducible results for the range of supported design sizes. Biomarkers were reliably detected with SNV detection down to 1% allele frequency, detection of gene amplifications and translocations concordant with FISH, and MSI and TMB determination concordant with PCR and Exome sequencing respectively. The design workspace was implemented in the SureDesign platform, providing a web-based interface for creating the designs. Conclusions: We demonstrated full customization capability of the SureSelect Cancer target enrichment platform that pairs user-defined content with an optimized probe design methodology to enable the sensitive detection of the common types of DNA alterations found in FFPE samples. Citation Format: Michael Ruvolo, Akanksha Khare, Nishita Matcha-Balaguruvappa, Katherine Wilkins, Linus Forsmark, Swati Gupta. NGS panel customization for comprehensive genomic profiling [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2935.

The length of the polyprobes and the position of the individual probes in them determine the sensitivity in the detection of viruses affecting pepper crops

The length of the polyprobes and the position of the individual probes in them determine the sensitivity in the detection of viruses affecting pepper crops

Modulating the Microenvironment of Coumarin Dyes within Multihierarchical Supraparticles: En Route toward Versatile Luminescent Dual‐Threshold Temperature Indicators with Ratiometric Readout

AbstractTemperature indicators trace (un)desired thermal impacts across their thermal history upon readout at every point of interest via defined irreversible signal changes. Ratiometric luminescent temperature indicators are attractive due to their fast, sensitive, contactless, spatially‐resolved, and self‐referenced readout. However, they have a limited working range as commonly only one specific temperature‐induced physicochemical effect is exploited. Herein, dual‐threshold temperature indicator supraparticles (SPs) are introduced that expand the working range of individual luminescent probes and enhance the extractable information on the thermal history. These SPs derive their functionality from the synergistic interplay of three spectrally distinguishable luminescent species assembled in one multihierarchical, micrometer‐sized particle of hybrid organic‐inorganic nature. This engineered nanostructure enables the stepwise modulation of the physicochemical microenvironment of two incorporated coumarin species at programmable threshold temperatures, resulting in distinct changes in their emission. As these changes are based on dye‐specific mechanisms that are induced in consecutive temperature regimes, the SPs achieve a scarcely reported broad working range (60–200 °C) with temperature‐dependent response times of minutes to seconds. From a broader perspective, the conceptualized SPs pioneer in how multiple individual luminescent probes with different excitation‐emission properties and indicator mechanisms are synergistically united in one advanced indicator system by precise material engineering.

Simultaneous Scanning Ion Conductance and Electrochemical Microscopy in Lithium‐Ion Battery Research

AbstractDeeper understanding of processes involved in operation of lithium‐ion batteries (LIBs) is necessary to further optimize them for future applications. Extensive research was conducted on the formation of a solid electrolyte interphase (SEI) on negative battery electrodes, still leaving several questions unanswered. Scanning probe microscopies (SPMs) enable in situ and operando investigations and have the potential to explain some phenomena. Scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM) could be employed in LIB studies. A novel SICM method based on the redox couple ferrocene/ferrocenium is introduced for applications in carbonate solvents widely used in LIBs. Proof of concept measurements were conducted with a micro milled copper circuit board as model substrate. Furthermore, the proposed SICM approach was hyphenated with feedback mode SECM resulting in the simultaneous mapping of morphology and electrochemical activity. A flexible dual‐probe arrangement was developed enabling usage of both SPM techniques at the same time, and furthermore, an easy replacement of both individual probes if needed. The setup was applied in the characterisation of commercial graphite electrodes for LIBs before and after conducting a pre‐charging protocol. Changes in electrochemical activity and topography of the graphite electrode were resolved in simultaneously generated SECM/SICM recordings.

Fluorescent-Probe Characterization for Pore-Space Mapping with Single-Particle Tracking.

Porous solids often contain complex pore networks with pores of various sizes. Tracking individual fluorescent probes as they diffuse through porous materials can be used to characterize pore networks at tens of nanometers resolution. However, understanding the motion behavior of fluorescent probes in confinement is crucial to reliably derive pore network properties. Here, we introduce well-defined lithography-made model pores developed to study probe behavior in confinement. We investigated the influence of probe-host interactions on diffusion and trapping of confined single-emitter quantum-dot probes. Using the pH-responsiveness of the probes, we were able to largely suppress trapping at the pore walls. This enabled us to define experimental conditions for mapping of the accessible pore space of a one-dimensional pore array as well as a real-life polymerization-catalyst-support particle.

Fluorescent‐Probe Characterization for Pore‐Space Mapping with Single‐Particle Tracking

AbstractPorous solids often contain complex pore networks with pores of various sizes. Tracking individual fluorescent probes as they diffuse through porous materials can be used to characterize pore networks at tens of nanometers resolution. However, understanding the motion behavior of fluorescent probes in confinement is crucial to reliably derive pore network properties. Here, we introduce well‐defined lithography‐made model pores developed to study probe behavior in confinement. We investigated the influence of probe‐host interactions on diffusion and trapping of confined single‐emitter quantum‐dot probes. Using the pH‐responsiveness of the probes, we were able to largely suppress trapping at the pore walls. This enabled us to define experimental conditions for mapping of the accessible pore space of a one‐dimensional pore array as well as a real‐life polymerization‐catalyst‐support particle.

Abstract B082: Interrogating the mechanistic link between neighborhood disadvantage colorectal cancer risk through DNA methylation analysis of African American colorectum

Abstract Environmental and social factors account for approximately 65% of colorectal cancer (CRC) risk. Identifying mechanisms associated with CRC risk may provide crucial insight for future drug targeting, as well as prevention and screening strategies. The Neighborhood Disadvantage Index (NDI) is a composite score of 17 social and environmental measures that has been shown to be associated with poorer health outcomes independently of an individual’s own socioeconomic status. While African Americans (AAs) are more likely to live in areas of high NDI, both non-Hispanic Whites and AAs living in areas of high NDI experience increased stress and poorer health. Recently, increased NDI scores have also been positively associated with CRC risk. The mechanisms through which these social factors influence disease risk are yet to be elucidated. DNA methylation represents one epigenetic marker that exists at the interplay between environment and disease risk. Here, we hypothesize that an analysis of NDI in an at-risk population for CRC will reveal DNA methylation differences relevant to disease. We performed genome-wide DNA methylation analysis of triple-matched, normal right and left colon, and rectal biopsies of 72 African Americans using the Illumina Infinium MethylationEPIC kit. After preprocessing of individual probes and samples, we generated a mixed-effects model to define differentially methylated regions (DMRs) that were consistently associated with NDI across all colorectal locations using DMRcate. The duplicateCorrelation function of Limma was used to account for repeated measures through addition of a random intercept. We identified 810 differentially methylated regions (DMRs) associated with NDI. Through gene-set enrichment analysis, we found that these DMRs were associated with CRC risk processes such as cell morphogenesis (FDR= 7.33E-05), development (FDR=1.18E-04) and growth (FDR=1.17E-02). Secondary analysis of five publicly available datasets revealed a subset of 17 that overlapped DMRs identified in all CRC tumor versus normal adjacent tissue analyses. To map DMRs to likely gene expression targets, further analysis was carried out in two, publicly available CRC tumor datasets. Our analysis found that of the 17 targets, eight were differentially expressed in TCGA-COAD with four of these also being differentially expressed in TCGA-READ. This included CAP-Gly domain containing linker protein family member 4 (CLIP4), which was reduced in TCGA-COAD (FDR=1.29E-28) and TCGA-READ (FDR=8.52E-08). DNA hypermethylation of chr2:29337946-29338121, which corresponded to CLIP4, was associated with increasing NDI in our analysis (FDR=0.040). Our study provides the first empirical evidence supporting DNA methylation as a plausible mechanism through which neighborhood socioeconomic disadvantage impacts colon carcinogenesis and drives disproportionately high risk of CRC among African Americans. Specifically, our findings indicate that epigenetic dysregulation of CLIP4 represents one potential marker of NDI-related disease risk. Citation Format: Matthew Devall, Xiangqing Sun, Stephen Eaton, Cynthia Yoshida, Samyukta Venkatesh, Gregory Cooper, Joseph Willis, Daniel Weisenberger, Graham Casey, Li Li. Interrogating the mechanistic link between neighborhood disadvantage colorectal cancer risk through DNA methylation analysis of African American colorectum [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr B082.

Increasing the capabilities of stationary neutron logging in determining the lithology of the carbonate section

The article presents a method of lithological identification of dolomites and limestones ac-cording to stationary neutron logging in several oil wells located on the territory of the Republic of Bashkortostan. The article presents a research of the influence of the mineral skeleton of rocks on the readings of stationary neutron logging and the use of differences in the values of porosity coefficients calculated from the readings of individual probes for the lithological identification of dolomites and limestones. Keywords: porosity; compensated neutron logging; neutron-neutron thermal neutron logging; neutron gamma-ray logging; lithological identification; carbonates; limestone; dolomite.

Development of a multi-needle fiberoptic Raman spectroscopy technique for simultaneous multi-site deep tissue Raman measurements in the brain.

We report on the development of a multi-needle fiberoptic Raman spectroscopy (MNF-RS) technique for simultaneous multi-site deep Raman measurements in brain tissue. The multi-needle fiberoptic Raman probe is designed and fabricated using a number of 100 µm core diameter, aluminum-coated fibers under a coaxial laser excitation and Raman collection scheme, enabling simultaneous collection of deep tissue Raman spectra from a number of tissue sites. We have also developed a Raman retrieval algorithm based on the transformation matrix of each individual needle fiber probe projected to different pixels of a charge-coupled device (CCD) for recovering the tissue Raman spectra collected by each needle fiber probe, allowing simultaneous multi-channel detection by a single Raman spectrometer. High-quality tissue Raman spectra of different tissue types (e.g., muscle, fat, gray matter, and white matter in porcine brain) can be acquired in both the fingerprint (900-1800 cm-1) and high-wavenumber (2800-3300 cm-1) regions within sub-second times using the MNF-RS technique. We also demonstrate that by advancing the multi-needle fiberoptic Raman probe into deep porcine brain, tissue Raman spectra can be acquired simultaneously from different brain regions (e.g., cortex, thalamus, midbrain, and cerebellum). The significant biochemical differences across different brain tissues can also be distinguished, suggesting the promising potential of the MNF-RS technique for label-free neuroscience study at the molecular level.