Spontaneous-stimulated Raman co-localization dual-modal analysis approach for efficient identification of tumor cells.

The study of highly heterogeneous tumor cells, especially acute myeloid leukemia (AML) cells, usually relies on invasive analytical methods such as morphology, immunology, cytogenetics, and molecular biology classification, which are complex and time-consuming to perform. Mortality is high if patients are not diagnosed in a timely manner, so rapid label-free analysis of gene expression and metabolites within single-cell substructures is extremely important for clinical diagnosis and treatment. As a label-free and non-destructive vibrational detection technique, spontaneous Raman scattering provides molecular information across the full spectrum of the cell but lacks rapid imaging localization capabilities. In contrast, stimulated Raman scattering (SRS) provides a high-speed, high-resolution imaging view that can offer real-time subcellular localization assistance for spontaneous Raman spectroscopic detection. In this paper, we combined multi-color SRS microscopy with spontaneous Raman to develop a co-localized Raman imaging and spectral detection system (CRIS) for high-speed chemical imaging and quantitative spectral analysis of subcellular structures. Combined with multivariate statistical analysis methods, CRIS efficiently differentiated AML from normal leukocytes with an accuracy of 98.1 % and revealed the differences in the composition of nuclei and cytoplasm of AML relative to normal leukocytes. Compared to conventional Raman spectroscopy blind sampling without imaging localization, CRIS increased the efficiency of single-cell detection by at least three times. In addition, using the same approach for further identification of AML subtypes M2 and M3, we demonstrated that intracytoplasmic differential expression of proteins is a marker for their rapid and accurate classifying. CRIS analysis methods are expected to pave the way for clinical translation of rapid tumor cell identification.

Label-Free Identification of AML1-ETO Positive Acute Myeloid Leukemia Using Single-Cell Raman Spectroscopy.

Acute myeloid leukemia (AML) is a malignant hematological tumor disease. Chromosomal abnormality is an independent prognostic factor in AML. AML with t(8:21) (q22; q22)/AML1-ETO (AE) is an independent disease group. In this research, a new method based on Raman spectroscopy is reported for label-free single-cell identification and analysis of AE fusion genes in clinical AML patients. Raman spectroscopy reflects the intrinsic vibration information of molecules in a label-free and non-destructive manner, and the fingerprint Raman spectrum of cells characterizes intracellular molecular types and relative concentration information, so as to realize the identification and molecular metabolism analysis of different kinds of cells. We collected the Raman spectra of bone marrow cells from clinically diagnosed AML M2 patients with and without the AE fusion gene. Through comparison of the average spectra and identification analysis based on multivariate statistical methods such as principal component analysis and linear discriminant analysis, the distinction between AE positive and negative sample cells in M2 AML patients was successfully achieved, and the single-cell identification accuracy was more than 90%. At the same time, the Raman spectra of the two types of cells were analyzed by the multivariate curve resolution alternating least squares decomposition method. It was found that the presence of the AE fusion gene may lead to the metabolic changes of lipid and nucleic acid in AML cells, which was consistent with the results of genomic and metabolomic multi-omics studies. The above results indicate that single-cell Raman spectroscopy has the potential for early identification of AE-positive AML.

Study of hydraulic cutting as a method to prevent coal burst disasters.

This study explores the causes of coal bursts in the Xinzhou Kiln Mine, identifying key factors such as residual pillars, hard coal seams and/or roofs, stress concentration due to complex geological structures, and the stress distribution characteristics of the primary rock. A significant finding is that hydraulic cutting not only diminishes and redistributes the stress concentration region inside the coal seam but also mitigates the burst potential of the coal-rock mass, fundamentally reducing the likelihood of coal bursts. By taking Face No. 8937 in Xinzhou Kiln Mine as the test object, a coal burst prevention test was performed using hydraulic cutting. In combination with theoretical analysis and numerical simulation, the mechanism of hydraulic cutting for preventing coal burst was discussed, and reasonable cutting parameters were established. Onsite monitoring revealed that hydraulic cutting disrupts the integrity of the coal-rock mass, releases internal stress, and increases its water content, thereby weakening its burst tendency. Additionally, the deformation and fracturing of the cutting slots and the closure of boreholes shifted the stress concentration from the coal seam to deeper areas and to the two ribs. Post-cutting observations showed a significant reduction in both the frequency and impact energy of coal bursts; there was also a noticeable increase in the convergence of the roadway in the cutting area compared to non-cutting areas. Furthermore, displacement of the roof and floor increased by 78.9 % and that of the two ribs increased by 47.4 % after cutting, preventing the coal-rock mass from accumulating high stress. In conclusion, hydraulic cutting is a promising method for effectively preventing coal bursts and enhancing the safety of mining operations.

Recognition of Nucleophosmin Mutant Gene Expression of Leukemia Cells Using Raman Spectroscopy.

As a label-free, nondestructive, and in situ detection method, Raman spectroscopy analysis of single cells has potential application value in biomedical fields such as cancer diagnosis. In this study, the Raman spectral characteristics of nucleophosmin (NPM1)-mutant acute myeloid leukemia (AML) cells and nonmutated AML cells were investigated, and the reasons for the differences in spectral peaks were explained in combination with transcriptomic analysis. Raman spectra of two AML cell lines without NPM1 mutation (THP-1 and HL-60) and the OCI-AML3 cell line carrying the NPM1 mutant gene were cultured and collected experimentally. It was found that the average Raman spectra of NPM1 mutant and nonmutated cells had intensity differences in multiple peaks corresponding to chondroitin sulfate (CS), nucleic acid, protein, and other molecules. The differentially expressed genes were identified by quantitative analysis of the gene expression matrix of the two types of cells, and their roles in the regulation of CS proteoglycan and protein synthesis were analyzed. The results showed that the differences between the two types of cells expressed by the single-cell Raman spectral information were consistent with the differences in transcriptional profiles. This research could advance the application of Raman spectroscopy in cancer cell typing.

Multistage microfluidic cell sorting method and chip based on size and stiffness.

High performance sorting of circulating tumor cells (CTCs) from peripheral blood is key to liquid biopsies. Size-based deterministic lateral displacement (DLD) technique is widely used in cell sorting. But conventional microcolumns have poor fluid regulation ability, which limits the sorting performance of DLD. When the size difference between CTCs and leukocytes is small (e.g., less than 3 µm), not only DLD, many size-based separation techniques fail due to low specificity. CTCs have been confirmed to be softer than leukocytes, which could serve as a basis for sorting. In this study, we presented a multistage microfluidic CTCs sorting method, first sorting CTCs using a size-based two-array DLD chip, then purifying CTCs mixed by leukocytes using a stiffness-based cone channel chip, and finally identifying cell types using Raman techniques. The entire CTCs sorting and analysis process was label free, highly pure, high-throughput and efficient. The two-array DLD chip employed a droplet-shaped microcolumn (DMC) developed by optimization design rather than empirical design. Attributed to the excellent fluid regulation capability of DMC, the CTCs sorter system developed by parallelizing four DMC two-array DLD chips was able to process a sample of 2.5 mL per minute with a recovery efficiency of 96.30 ± 2.10% and a purity of 98.25 ± 2.48%. To isolate CTCs mixed dimensionally by leukocytes, a cone channel sorting method and chip were developed based on solid and hydrodynamic coupled analysis. The cone channel chip allowed CTCs to pass through the channel and entrap leukocytes, improving the purity of CTCs mixed by leukocytes by 1.8-fold.

Micro two-dimensional slit-array for super resolution beyond pixel Nyquist limits in grating spectrometers.

This paper presents a new micro 2-D slit-array device for spectral resolution enhancement in grating spectrometers. The 2-D slit-array is encoded in Hadamard matrix and the device is fabricated based on the micro-electromechanical system (MEMS) technology. By just using this 2-D slit-array to replace the single slit in the conventional grating spectrometer, real-time super spectral resolution detection beyond the pixel Nyquist limit, which is determined by the size of the detector pixel, can be realized. Furthermore, no other configuration of the spectrometer is changed, no movable parts are used, and the spectral range and instrument size remain almost unchanged while the resolution is improved. A series of experimental verifications for the feasibility of this design are included in this work.

Determining the scale of coal mining in an ecologically fragile mining area under the constraint of water resources carrying capacity.

A reasonable mining scale is very important for the development of mining areas. In view of the lack of water resources in arid and semi-arid areas, this paper studies the scale of coal mining in arid and semi-arid areas under the constraint of the water resources carrying capacity (WRCC) with the aim of realizing the conservation mining of ecological environment. From the perspectives of market demand side, production side and the constraint side, a "trinity" decision model was constructed to investigate the main factors influencing the scale of coal mining. By introducing the optimal control theory with profit taken as objective function, the coal price and coal reserves were regarded as boundary conditions, and WRCC was set as constraint condition. Based on H-J-B equation algorithm, the decision-making equation for mining scale under the constraints of market demand and WRCC was obtained. Through comparing the mining scales under the two constraints, the mode of "water-based mining scale" was formulated, which is conductive for realizing the balance between coal mining and ecological environment development.

Fabrication and Characterization of Curved Compound Eyes Based on Multifocal Microlenses.

Curved compound eyes have generated great interest owing to the wide field of view but the application of devices is hindered for the lack of proper detectors. One-lens curved compound eyes with multi-focal microlenses provide a solution for wide field imaging integrated in a commercial photo-detector. However, it is still a challenge for manufacturing this kind of compound eye. In this paper, a rapid and accurate method is proposed by a combination of photolithography, hot embossing, soft photolithography, and gas-assisted deformation techniques. Microlens arrays with different focal lengths were firstly obtained on a polymer, and then the planar structure was converted to the curved surface. A total of 581 compound eyes with diameters ranging from 152.8 µm to 240.9 µm were successfully obtained on one curved surface within a few hours, and the field of view of the compound eyes exceeded 108°. To verify the characteristics of the fabricated compound eyes, morphology deviation was measured by a probe profile and a scanning electron microscope. The optical performance and imaging capability were also tested and analyzed. As a result, the ommatidia made up of microlenses showed not only high accuracy in morphology, but also imaging uniformity on a focal plane. This flexible massive fabrication of compound eyes indicates great potential for miniaturized imaging systems.

An Improved Background-Correction Algorithm for Raman Spectroscopy Based on the Wavelet Transform.

In the traditional background correction algorithm based on the wavelet transform, approximation coefficients considered as frequency responses of background signal are usually set to zero. However, there are many meaningless negative values generated in the background-corrected spectrum because of the calibration errors of this algorithm. Intensities of some weak peaks even become negative and these peaks will disappear after the calibration of negative values. To solve these problems for the background correction of Raman spectrum, an improved intelligent algorithm which utilizes a suppression coefficient to modify approximation coefficients is proposed in this paper. A series of simulation analyses, as well as experimental investigations, are made to test the performance of this algorithm. It is proved that the use of the suppression coefficient could increase the background correction accuracy and decrease the number of meaningless negative values in the reconstructed spectra, which will prevent the disappearance of weak Raman peaks after the calibration of negative values and increase the sensitivity of Raman spectral analysis.

Multiwavelength Regression Algorithm for Eliminating Chamber Surface Effects of Microfluidic Chips.

An ultraviolet visible (UV-Vis) spectrophotometric and multiwavelength linear regression (MLR) method was developed for eliminating the influence of the surface quality of centrifugal microfluidic chips on the accuracy of their absorbance detection. The regression model is based on scalar scattering theory. The method was validated with cuvettes with different surface quality and Orange G (orange gelb) dye. The coefficients of variation (CVs) of the predicted solution concentration ratios in different cuvettes were < 1%, and the relative errors were < 1.5%. The model was shown to have higher accuracy and precision than that of traditional methods.

Ultrasensitive label-free optical microfiber coupler biosensor for detection of cardiac troponin I based on interference turning point effect.

Sensitive detection of cardiac biomarkers is critical for clinical diagnostics of myocardial infarction (MI) while such detection is quite challenging due to the ultra-low concentration of cardiac biomarkers. In this work, a label-free immunosensor based on optical microfiber coupler (OMC) has been developed for the ultrasensitive detection of cardiac troponin I (cTnI), a selective and highly sensitive biomarker of acute myocardial infarction (AMI). CTnI monoclonal antibodies were immobilized on the surface of the fiber through polyelectrolyte layer using layer-by-layer deposition technique. For refractive index sensing characterization, an ultra-high sensitivity of 91777.9 nm/RIU was achieved when the OMC works around the dispersion turning point, which is the highest experimental demonstration in the field of fiber-optic evanescent biosensors. For biosensing, the immunosensor with good specificity showed a linear wavelength shift in the range of 2-10 fg/mL and an ultra-low detection limit of 2 fg/mL. Such immunosensors have huge application potential for the detection of cardiac biomarkers of myocardial infarction due to simple detection scheme, quick response time, ease of handling and miniaturation.

Signal-to-noise ratio enhancement of a Hadamard transform spectrometer using a two-dimensional slit-array.

The encoding and decoding principle of the Hadamard transform spectrometer with a 2D slit-array mask is described in this paper. Based on the Hadamard transform theory, the signal-to-noise ratio (SNR) enhancement of a 2D slit-array Hadamard transform spectrometer is deduced and verified experimentally. Affected by the optical system of the spectrometer, there are differences between the experimental results and theoretical calculations. At the end of this paper, we discuss the influence of the spectrometer's optical system on the SNR enhancement based on the spatial frequency analysis.

Coupled-mode induced transparency in a bottle whispering-gallery-mode resonator.

Whispering-gallery-mode (WGM) optical resonators are ideal systems for achieving electromagnetically induced transparency-like phenomenon. Here, we experimentally demonstrate that one or more transparent windows can be achieved with coupled-mode induced transparency (CMIT) in a single bottle WGM resonator due to the bottle's dense mode spectra and tunable resonant frequencies. This device offers an approach for multi-channel all-optical switching devices and sensitivity-enhanced WGM-based sensors.

Encoded error calibration for a coded aperture spectrometer based on deconvolution.

The principle of a 2D coded aperture spectrometer is described in this paper. The crosstalk of adjacent rows, which is caused by the optical system's point-spread function and the nonuniform illumination of the apertures, is the main source of the system decoded errors. Through the analysis of the effect of the crosstalk and nonuniform illumination on the decoded spectrum, the encoding matrix is modified. Based on the new encoding equation, an algorithm using Gold's deconvolution method is proposed to remove the crosstalk of adjacent rows. In the end, we evaluate the effect of this method through a series of contrast experiments.

Polarization-independent and omnidirectional nearly perfect absorber with ultra-thin 2D subwavelength metal grating in the visible region.

A polarization-independent and omnidirectional nearly perfect absorber in the visible region has been proposed. The absorber is two-layer structure consisting of a subwavelength metal grating layer embedded in the high refractive index and lossless dielectric layer on the metal substrate. Extraordinary optical absorption with absorption peaks of over 99% can be achieved over the whole visible region for both TM and TE polarization. This absorption is attributed to cavity mode (CM) resonance caused by the coupled surface plasmon polaritons (SPP). Through adjusting the grating thickness, the absorption peak can be tuned linearly, which is highly advantageous to design various absorbers. Furthermore, the absorbance retains ultra-high over a wide angular range of incidence for both TM and TE polarization. This nearly perfect absorber offers great potential in the refractive index (RI) sensors, integrated photodetectors, solar cells and so on.

Avoiding the side-effect of high-performance spectrometers with coded apertures.

In this report, a high-resolution, high-signal-to-noise-coded aperture spectrometer is introduced that replaces the traditional single slit with two-dimensional array slits manufactured by microelectromechanic system technology. The encoding and decoding principle of this coded aperture spectrometer is described, as well as the instrument structure. We then discuss the side-effect, which is caused by sub-aperture manufacturing errors in size and position and the smear noise in the imaging CCD. The side-effect adversely affects the decoding wavelength accuracy of this spectrometer, so we present some effective ways to avoid this phenomenon and to increase the decoding wavelength accuracy of the spectrometer. In the end, we present our experimental results.

[Study on the wavelength accuracy of the 2-D slit-array Hadamard spectrometer].

The 2-D slit array mask is a new design of Hadamard spectrometer mask. Having discussed the influence of the inconsistency caused by the machining errors in the size and location between the slits in the same column on the wavelength accuracy of the Hadamard spectrometer, the authors bring up with the way to decrease the influence on the wavelength accuracy of the spectrometer caused by the difference in the height and location vertical to the spectrum between the slits in the same column, and then estimate the spectral shift caused by the relative location shift along the spectrum between the slits in the same column. A model for simulation was built, and the measurement errors in the decoded spectrum generated by one column of the slits on the mask were calculated, when there are inconsistency errors in width and location along the spectrum between the slits in another column. Based on the simulation calculation, we can determine the machining precision of the mask. The research will be meaningful to the design of the 2-D slit array mask using MEMS(micro-electro-mechanism system) technique and the revise of the decoded spectrum, which can provide the spectrometer with a reasonable wavelength accuracy.