Zn Single-Atom Catalysts Enable the Catalytic Transfer Hydrogenation of α,ß-Unsaturated Aldehydes.

Highly active nonprecious-metal single-atom catalysts (SACs) toward catalytic transfer hydrogenation (CTH) of α,ß-unsaturated aldehydes are of great significance but still are deficient. Herein, we report that Zn-N-C SACs containing Zn-N3 moieties can catalyze the conversion of cinnamaldehyde to cinnamyl alcohol with a conversion of 95.5% and selectivity of 95.4% under a mild temperature and atmospheric pressure, which is the first case of Zn-species-based heterogeneous catalysts for the CTH reaction. Isotopic labeling, in situ FT-IR spectroscopy, and DFT calculations indicate that reactants, coabsorbed at the Zn sites, proceed CTH via a "Meerwein-Ponndorf-Verley" mechanism. DFT calculations also reveal that the high activity over Zn-N3 moieties stems from the suitable adsorption energy and favorable reaction energy of the rate-determining step at the Zn active sites. Our findings demonstrate that Zn-N-C SACs hold extraordinary activity toward CTH reactions and thus provide a promising approach to explore the advanced SACs for high-value-added chemicals.

Probing calmodulin-NO synthase interactions via site-specific infrared spectroscopy: an introductory investigation.

Calmodulin (CaM) binds to a linker between the oxygenase and reductase domains of nitric oxide synthase (NOS) to regulate the functional conformational dynamics. Specific residues on the interdomain interface guide the domain-domain docking to facilitate the electron transfer in NOS. Notably, the docking interface between CaM and the heme-containing oxygenase domain of NOS is isoform specific, which is only beginning to be investigated. Toward advancing understanding of the distinct CaM-NOS docking interactions by infrared spectroscopy, we introduced a cyano-group as frequency-resolved vibrational probe into CaM individually and when associated with full-length and a bi-domain oxygenase/FMN construct of the inducible NOS isoform (iNOS). Site-specific, selective labeling with p-cyano-L-phenylalanine (CNF) by amber suppression of CaM bound to the iNOS has been accomplished by protein coexpression due to the instability of recombinant iNOS protein alone. We introduced CNF at residue 108, which is at the putative CaM-heme (NOS) docking interface. CNF was also introduced at residue 29, which is distant from the docking interface. FT IR data show that the 108 site is sensitive to CaM-NOS complex formation, while insensitivity to its association with the iNOS protein or peptide was observed for the 29 site. Moreover, narrowing of the IR bands at residue 108 suggests the C≡N probe experiences a more limited distribution of environments, indicating side chain restriction apparent for the complex with iNOS. This initial work sets the stage for residue-specific characterizations of structural dynamics of the docked states of NOS proteins.

Biomolecular fingerprints of the effect of zoledronic acid on prostate cancer stem cells: Comparison of 2D and 3D cell culture models.

Revealing the potential of candidate drugs against different cancer types without disrupting normal cells depends on the drug mode of action. In the current study, the drug response of prostate cancer stem cells (PCSCs) to zoledronic acid (ZOL) grown in two-dimensional (2D) and three-dimensional (3D) culture systems was compared using Fourier transform-infrared (FT-IR) spectroscopy which is a vibrational spectroscopic technique, supporting by biochemical assays and imaging techniques. Based on our data, in 2D cell culture conditions, the ZOL treatment of PCSCs isolated according to both C133 and CD44 cell surface properties induced early/late apoptosis and suppressed migration ability. The CD133 gene expression and protein levels were altered, depending on culture systems. CD133 expression was significantly reduced in 2D cells upon ZOL treatment. FT-IR data revealed that the integrity, fluidity, and ordering/disordering states of the cell membrane and nucleic acid content were altered in both 2D and 3D cells after ZOL treatment. Regular protein structures decrease in 2D cells while glycogen and protein contents increase in 3D cells, indicating a more pronounced cytotoxic effect of ZOL for 2D cells. Untreated 3D PCSCs exhibited an even different spectral profile associated with IR signals of lipids, proteins, nucleic acids, and glycogen in comparison to untreated 2D cells. Our study revealed significant differences in the drug response and cellular constituents between 2D and 3D cells. Exploring molecular targets and/or drug-action mechanisms is significant in cancer treatment approaches; thus, FT-IR spectroscopy can be successfully applied as a novel drug-screening method in clinical research.

Role of Constituent Oxides for Thermal Mineralization of o-Dichloro Benzene over Mixed-Oxide-TiO2 Catalysts: A Mechanistic Explanation.

Catalysts with V2O5, WO3 and V2O5-WO3 dispersed over TiO2 were synthesized using sol-gel technique and thoroughly characterized by various techniques. The catalysts were evaluated for degradation of ortho-dichloro benzene (o-DCB) in air/helium, a representative probe molecule for polychlorinated dibenzo-para-dioxin and polychlorinated dibenzofuran by employing in situ Fourier-transform infrared spectroscopy (FT-IR spectroscopy). Different intermediate species formed on the surface of the TiO2 supported catalysts through of interaction of sorbate molecules with the lattice and/or gaseous oxygen were investigated in detail. Analysis of vibrational bands, observed during sorption of o-DCB and o-DCB-air mixture as a function of temperature over these catalysts, delineated the role of surface intermediate species such as phenolate, enolates, maleates, carboxylates, carbonates in mineralization of o-DCB. Nature and stability of intermediate species, found to be different over these catalysts, were able to elucidate the catalytic activity trend.

N-doped TiO2/rGO: synthesis, structure, optical characteristics, and humidity sensing applications.

In the current study, the effect of rGO ratio on the N-dopped TiO2has been synthesized through sol-gel method. The prepared N-doped TiO2/rGO composites were examined for humidity sensing applications. The relationship between optical properties and the humidity sensing properties was studied. The structure, morphology, and bonding interaction have been examined using XRD, FT-IR, PL and HRTEM respectively. The average particle size as estimated from XRD and HRTEM was found to be about 9 nm. The optical properties have been studied using UV/ Vis. Spectroscopy. Further, optical parameters including refractive index and optical band gap energy have been estimated. The humidity sensing behavior of the resultant composites were evaluated in a wide range of humidity (7%-97% RH) at different testing frequencies. The optical band gap was found to be decreased as the amount of rGO increase. Among all prepared samples, both the optical parameters and humidity sensing experiments confirmed that the 0.5% rGO@N-dopped TiO2sample is the best candidate for the humidity sensing applications. The best optimum testing frequency was demonstrated to be 50 Hz. The sensor demonstrates a fast response and recovery times of 13 s and 33 s with low hysteresis and large sensitivity. The humidity sensing mechanism was studied using complex impedance spectroscopy at different RH levels under testing frequency range from 50 Hz to 5 MHz and testing voltage of 1 VAC. The produced structure demonstrated a promising material for humidity measuring devices.

Hotspots of Floating Plastic Particles across the North Pacific Ocean.

The pollution of the marine environment with plastic debris is expected to increase, where ocean currents and winds cause their accumulation in convergence zones like the North Pacific Subtropical Gyre (NPSG). Surface-floating plastic (>330 µm) was collected in the North Pacific Ocean between Vancouver (Canada) and Singapore using a neuston catamaran and identified by Fourier-transform infrared spectroscopy (FT-IR). Baseline concentrations of 41,600-102,700 items km-2 were found, dominated by polyethylene and polypropylene. Higher concentrations (factors 4-10) of plastic items occurred not only in the NPSG (452,800 items km-2) but also in a second area, the Papaha̅naumokua̅kea Marine National Monument (PMNM, 285,200 items km-2). This second maximum was neither reported previously nor predicted by the applied ocean current model. Visual observations of floating debris (>5 cm; 8-2565 items km-2 and 34-4941 items km-2 including smaller "white bits") yielded similar patterns of baseline pollution (34-3265 items km-2) and elevated concentrations of plastic debris in the NPSG (67-4941 items km-2) and the PMNM (295-3748 items km-2). These findings suggest that ocean currents are not the only factor provoking plastic debris accumulation in the ocean. Visual observations may be useful to increase our knowledge of large-scale (micro)plastic pollution in the global oceans.

Interference between Escherichia coli genotypes from the E. coli peritonitis syndrome given simultaneously to productive SPF White Leghorn hens by intratracheal inoculation.

The purpose of the present study was to examine if potentiation of mortality occurred after simultaneous administration of several Escherichia coli genotypes, each capable of inducing the E. coli peritonitis syndrome, in comparison with single genotype application. Five groups of productive specified pathogen free White Leghorn hens were housed in isolators. Groups 1-4 consisted of 32 hens each, group 5 of 10 hens. At 32 weeks of age all groups were inoculated intratracheally. Groups 1 and 2 were inoculated with a mix of four E. coli genotypes and groups 3 and 4 with a mix of four other genotypes. Groups 1 and 3 were given 1 median lethal dose (LD50) of each genotype per hen and groups 2 and 4 had a dose of 0.1 LD50 per genotype per hen; group 5 was mock inoculated. The experiment ended one week after inoculations. In Group 5, no mortality occurred and gross lesions were absent at post-mortem examination. Mortality in groups 1 and 3 was 84% and 81%, respectively; in groups 2 and 4 59% and 66%, respectively. Although mortality in groups 1 and 3 exceeded the expected 50%, this could not be due to potentiation as cluster analysis of reisolates showed that in individual hens only one genotype was found, indicating interference between E. coli genotypes. In groups all four or only two genotypes were recovered, showing that not all genotypes will induce colibacillosis in all experimental groups. Therefore, broad protection can be best assessed by challenging with various single genotypes.RESEARCH HIGHLIGHTS All four or only two E. coli genotypes were found in groups of hens given mixes of four genotypes.In contrast, only one genotype was found in individual hens.E. coli genotypes interfere with each other in hens after given as a mix.Interference is likely based on a random process.Broad protection can best be assessed by challenging with single genotypes.

Unveiling microplastics pollution in a subtropical rural recreational lake: A novel insight.

While global attention has been primarily focused on the occurrence and persistence of microplastics (MP) in urban lakes, relatively little attention has been paid to the problem of MP pollution in rural recreational lakes. This pioneering study aims to shed light on MP size, composition, abundance, spatial distribution, and contributing factors in a rural recreational lake, 'Nikli Lake' in Kishoreganj, Bangladesh. Using density separation, MPs were extracted from 30 water and 30 sediment samples taken from ten different locations in the lake. Subsequent characterization was carried out using a combination of techniques, including a stereomicroscope, Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FE-SEM). The results showed a significant prevalence of MPs in all samples, with an average amount of 109.667 ± 10.892 pieces/kg3 (dw) in the sediment and 98.167 ± 12.849 pieces/m3 in the water. Small MPs (<0.5 mm), fragments and transparent colored particles formed the majority, accounting for 80.2%, 64.5% and 55.3% in water and 78.9%, 66.4% and 64.3% in sediment, respectively. In line with global trends, polypropylene (PP) (53%) and polyethylene (PE) (43%) emerged as the predominant polymers within the MPs. MP contents in water and sediment showed positive correlations with outflow, while they correlated negatively with inflow and lake depth (p > 0.05). Local activities such as the discharge of domestic sewage, fishing waste and agricultural runoff significantly influence the distribution of polypropylene. Assessment of pollution factor, pollution risk index and pollution load index values at the sampling sites confirmed the presence of MPs, with values above 1. This study is a baseline database that provides a comprehensive understanding of MP pollution in the freshwater ecosystem of Bangladesh, particularly in a rural recreational lake. A crucial next step is to explore ecotoxicological mechanisms, legislative measures and future research challenges triggered by MP pollution.

Raman spectroscopy is a powerful tool in molecular paleobiology: An analytical response to Alleon et al. (https://doi.org/10.1002/bies.202000295).

A recent article argued that signals from conventional Raman spectroscopy of organic materials are overwhelmed by edge filter and fluorescence artefacts. The article targeted a subset of Raman spectroscopic investigations of fossil and modern organisms and has implications for the utility of conventional Raman spectroscopy in comparative tissue analytics. The inferences were based on circular reasoning centered around the unconventional analysis of spectra from just two samples, one modern, and one fossil. We validated the disputed signals with in situ Fourier-Transform Infrared (FT-IR) Spectroscopy and through replication with different lasers, filters, and operators in independent laboratories. Our Raman system employs a holographic notch filter which is not affected by edge filter or other artefacts. Multiple lines of evidence confirm that conventional Raman spectra of fossils contain biologically and geologically meaningful information. Statistical analyses of large Raman and FT-IR spectral data sets reveal patterns in fossil composition and yield valuable insights into the history of life.

Spectroscopic characterization and pharmacokinetic evaluation of amorphous solid dispersions of glibenclamide for bioavailability enhancement in Wistar rats.

Oral bioavailability of glibenclamide (Glb) was appreciably improved by the formation of an amorphous solid dispersion with Poloxamer-188 (P-188). Poloxamer-188 substantially enhanced the solubility and thereby the dissolution rate of the biopharmaceutics classification system (BCS) class II drug Glb and simultaneously exhibited a better stabilizing effect of the amorphous solid dispersion prepared by the solvent evaporation method. The physical state of the dispersed Glb in the polymeric matrix was characterized by differential scanning calorimetry, X-ray diffraction, scanning electron microscope and Fourier transform infrared studies. In vitro drug release in buffer (pH 7.2) revealed that the amorphous solid dispersion at a Glb-P-188 ratio of 1:6 (SDE4) improved the dissolution of Glb by 90% within 3 h. A pharmacokinetic study of the solid dispersion formulation SDE4 in Wistar rats showed that the oral bioavailability of the drug was greatly increased as compared with the market tablet formulation, Daonil®. The formulation SDE4 resulted in an AUC0-24h ~2-fold higher. The SDE4 formulation was found to be stable during the study period of 6 months.

Photoluminescence properties of Pb5(PO4)3Br:RE (RE = Dy3+, Eu3+ and Tb3+) phosphor synthesised using solid-state method.

This study describes the luminous properties of Pb5(PO4)3Br doped with RE3+ (RE = Dy3+, Eu3+ and Tb3+) synthesised using the solid-state method. The synthesised phosphor was characterised using Fourier-transform infrared, X-ray diffraction, scanning electron microscopy and photoluminescence measurements. Dy3+-doped Pb5(PO4)3Br phosphor exhibited blue and yellow emissions at 480 and 573 nm, respectively, on excitation at 388 nm. Eu3+-doped Pb5(PO4)3Br phosphor exhibited orange and red emissions at 591 and 614 nm, respectively, on excitation at λex = 396 nm. Pb5(PO4)3Br:Tb3+ phosphor exhibited the strongest green emission at 547 nm on excitation at λex = 380 nm. Additionally, the effect of the concentration of rare-earth ions on the emission intensity of Pb5(PO4)3Br:RE3+ (RE3+ = Dy3+, Eu3+ and Tb3+) phosphors was investigated.

The Invisible Fraction within Melanin Capable of Absorbing UV Light and with Fluorescent Properties: Is It Lacking Consideration?

Expanding on earlier observations, we show that many melanin materials, in vitro synthesized from a wide range of precursors, can be fractionated into a dark-colored precipitate and a near-colorless, dispersible fraction. The dispersible fractions exhibited absorbance in the UVA and UVB range of the electromagnetic spectrum, but none in the visible range. In addition, fluorescent properties were associated with all dispersible fractions obtained. FT-IR spectroscopic analyses were performed to compare both types of fractions. Overall, it appears that some of the properties associated with melanin (UV absorbance, fluorescence) may not necessarily reside in the dark-colored portion of melanin, but in a colorless fraction of the material. It remains to be seen whether any of these in vitro observations have any relevance in vivo. However, we raise the possibility that the presence of a colorless fraction within melanin materials and their associated properties may have received inadequate attention. Given the important association between melanin, UV protection, and skin cancer, it is worthwhile to consider this additional aspect of melanin chemistry.

Silver-Loaded Chabazite in Ethanol-to-Hydrocarbon Process-Operando FT-IR and UV-Vis Spectroscopic Studies.

The ethanol dehydration process is studied regarding protonic and Ag-loaded chabazite zeolite in advanced FT-IR and UV-vis operando spectroscopic studies with simultaneous mass spectroscopy and gas chromatography analyses of products. The spectroscopic investigation provides information on the species formed on the surface of catalysts, while mass spectrometry and gas chromatography methods identify the desorbed products. These studies are also supported by spectroscopic, chromatographic, and thermogravimetric analyses of coke species formed over the catalyst's surface during ethanol conversion. The Ag-chabazite catalyst shows higher selectivity for ethylene and propylene; the slower formation of coke species; and, thus, a longer lifetime.

Structural Characterization and Electrochemical Studies of Selected Alkaloid N-Oxides.

In this work, we synthesized and confirmed the structure of several alkaloid N-oxides using mass spectrometry and Fourier-transform infrared spectroscopy. We also investigated their reduction mechanisms using voltammetry. For the first time, we obtained alkaloid N-oxides using an oxidation reaction with potassium peroxymonosulfate as an oxidant. The structure was established based on the obtained fragmentation mass spectra recorded by LC-Q-ToF-MS. In the FT-IR spectra of the alkaloid N-oxides, characteristic signals of N-O group vibrations were recorded (bands in the range of 928 cm⁻1 to 971 cm⁻1), confirming the presence of this functional group. Electrochemical reduction studies demonstrated the reduction of alkaloid N-oxides at mercury-based electrodes back to the original form of the alkaloid. For the first time, the products of the electrochemical reduction of alkaloid N-oxides were detected by mass spectrometry. The findings provide insights into the structural characteristics and reduction behaviors of alkaloid N-oxides, offering implications for pharmacological and biochemical applications. This research contributes to a better understanding of alkaloid metabolism and degradation processes, with potential implications for drug development and environmental science.

Assessment of Iron Biosorption Potential by Live and Dead Biomass of Bacillus subtilis (MN093305) from Aqueous Solution.

Heavy metals polluted aquatic ecosystems and become a global environmental issue due to their toxic effect on all forms of ecosystems and further on all forms of life. Heavy metals are non- degradable and accumulated in different life forms by accumulating in the food chain; this increases the need for the development of a sustainable method for the removal of these metals. Biosorption is an eco-friendly and cost-effective convenient technique of heavy metal bioremediation from the contaminated aquatic ecosystem. The current investigation involves biosorption of iron using Bacillus subtilis strain (MN093305) isolated from Ganga river at different physical parameters with the highest rate of biosorption was 96.64%, 98.91%, 97.88%, and 99.44% at pH 5, 60 min incubation period, 35 °C temperature and 2.5 mg/ml of biomass respectively for dead biomass. Living biomass biosorption rate was 87.32%, 96.74%, 96.94% and 95.02% at pH 7, 72 h, 35 °C and 2.5 mg/ml respectively. Functional groups involved in the biosorption of iron by Bacillus subtilis were fitted to a second-order kinetic model. Langmuir and Freundlich's isotherm are used to evaluate data; both isotherms indicate iron absorption as a favorable process.

A study on incorporation of giloy (Tinosporacordifolia) for the development of shelf-stable goat milk based functional beverage.

Goat milk has achieved significant place in human diet owing to its enormous therapeutic properties. There exists a scope of value-addition of goat milk to potentiate its health benefits by incorporating herbs and plants. Giloy (Tinospora cordifolia), a traditional medicinal plant with rich bioactive composition, can enhance the bioactive properties and shelf-life of goat milk. To this end, a study was conducted to develop shelf-stable giloy-goat milk beverage (GGB) by adding debittered giloy juice to goat milk (GM) and analyse the detailed product profile including proximate composition, bioactive properties, sensory, rheological, and structural characterisation. GGB resulted in two-fold increase (P < 0.05) in antioxidant activity and total phenolic content, thus enhancing the bioactive properties of the beverage as compared to GM. Further, increase in the particle size of GGB was observed along with components interaction, which was confirmed by FTIR, scanning electron and fluorescent microscopy. Storage stability studies indicated that bioactive properties of GGB remained unaffected (P > 0.05) by the sterilization process up to 90 days and sensory characteristics were not compromised till 105 days of storage. Therefore, the developed GGB is considered to be a shelf-stable beverage that retains its bioactive and sensory properties even after sterilization, making it a promising functional dairy product.

Optimizations of exopolysaccharide production by Fusarium nygamai strain AJTYC1 and its potential applications as an antioxidant, antimicrobial, anticancer, and emulsifier.

BACKGROUND: Exopolysaccharides (EPSs) produced by microbes are recognized as biomacromolecules of great significance. EPSs from fungi are widely used in a variety of biotechnological fields, including medicine, bioremediation, and agriculture. RESULTS: In this study, ten fungal isolates were isolated from Kafir El-Dair, Qalubia Governorate, Egypt. Isolate 5 produced more exopolysaccharides than the other examined fungi. According to microscopic morphological traits and genetic confirmation by the 18S rRNA gene, isolate 5 was identified as Fusarium nygamai strain AJTYC1. The present study showed that Czapek's broth media, which contains 6 g/100 ml of sucrose, 10 g/100 ml of peptone, pH 6, and 1.8 × 105 CFU/ml of inoculum size and is incubated at 30 °C for 9 days, was suitable for the production of EPSs from Fusarium nygamai strain AJTYC1 by using static conditions. Fourier transform infrared (FT-IR) was employed in the characterization of EPSs, which exhibited the presence of carboxyl groups, hydroxyl groups, carbonyl groups, and glycosidic bonds. High-performance liquid chromatography (HPLC) detected that EPSs consist of sucrose and glucose. The scavenging activity indicates that EPSs have good antioxidant activity. The partially purified exopolysaccharides produced from F. nygamai strain AJTYC1 exhibited excellent antioxidant and antimicrobial activity against gram positive, gram negative and fungal strains. The EPSs at a dose of 1000 µg/ml exhibited anticancer activity against colorectal colon cancer (HCT116), breast cancer (MCF7), and hepatocellular cancer cell lines. Moreover, EPSs is an effective emulsifier of a variety of vegetable oils, and the emulsion it produces is generally stable for up to 168 h. CONCLUSIONS: The production of EPSs from F. nygamai strain AJTYC1 can be used as antioxidants, antimicrobials, anticancer, and emulsifiers.

The surface and internal features of pubic hair: A comparative study with those of scalp hair.

Although pubic hair has been a subject of public interest, little is known about its structure or characteristics beyond its curly and coarse appearance. In this study, we investigated the surface and internal features of pubic hair from Korean males and compared them to those of scalp hair from the same donors. Our findings indicate that the cuticle layer of pubic hair has a greater number of scales than that of scalp hair, resulting in a thicker cuticle layer overall. Fourier-transform infrared (FT-IR) spectroscopy analysis showed that the protein in the cortex layer of pubic hair was less affected by exposure to urine or ammonia than the protein in the cortex layer of scalp hair. This suggests that the cuticle layer of pubic hair, which is thicker and composed of more scales, acts as a physical barrier that protects the hair's internal structure. Furthermore, we observed that the secondary and tertiary structures of keratin in the pubic hair cuticle layer are essentially different from those in scalp hair. Based on these findings, we hypothesize that the thickened cuticle layer in pubic hair may have evolved as a defence mechanism against chemical damage from urine, urea and ammonia.

Polysaccharides from Spirulina platensis (PSP): promising biostimulants for the green synthesis of silver nanoparticles and their potential application in the treatment of cancer tumors.

Photosynthetic cyanobacterial components are gaining great economic importance as prospective low-cost biostimulants for the green synthesis of metal nanoparticles with valuable medical and industrial applications. The current study comprises the biological synthesis of silver nanoparticles (Ag-NPs) using soluble polysaccharides isolated from Spirulina platensis (PSP) as reducing and capping agents. FTIR spectra showed major functional groups of PSP and biogenic silver nanoparticles including O-H, C-H (CH2), C-H (CH3), C=O, amide, and COO- groups. The UV/Vis spectroscopy scan analyses of the extracted PSP showed absorption spectra in the range of 200-400 nm, whereas the biogenic Ag-NPs showed a maximum spectrum at 285 nm. Transmission electron microscopy (TEM) analysis of the synthesized Ag-NPs showed spherical nanoparticles with mean size between 12 and 15.3 nm. The extracted PSP and Ag-NPs exhibited effective cytotoxic activity against Hep-G2 (human hepatocellular carcinoma). The IC50 for PSP and Ag-NPs were 65.4 and 24.5 µg/mL, respectively. Moreover, cell apoptosis assays for PSP and Ag-NPs against the growth of Hep-G2 cells revealed superior growth inhibitory effects of the green synthesized Ag-NPs that encouraged tracing the apoptotic signalling pathway. In conclusion, the current study demonstrated an unprecedented approach for the green synthesis of silver nanoparticles (NPs), using the polysaccharide of Spirulina platensis as reducing and capping agents, with superior anticancer activity against a hepatocellular carcinoma cell line.

Spectral Classification of Large-Scale Blended (Micro)Plastics Using FT-IR Raw Spectra and Image-Based Machine Learning.

Microplastics (MPs) are currently recognized as emerging pollutants; their identification and classification are therefore essential during their monitoring and management. In contrast to most studies based on small datasets and library searches, this study developed and compared four machine learning-based classifiers and two large-scale blended plastic datasets, where a 1D convolutional neural network (CNN), decision tree, and random forest (RF) were fed with raw spectral data from Fourier transform infrared spectroscopy, while a 2D CNN used the corresponding spectral images as the input. With an overall accuracy of 96.43% on a small dataset and 97.44% on a large dataset, the 1D CNN outperformed other models. The 1D CNN was the best at predicting environment samples, while the RF was the most robust with less spectral data. Overall, RF and 2D CNNs might be evaluated for plastic identification with fewer spectral data; however, 1D CNNs were thought to be the most effective with sufficient spectral data. Accordingly, an open-source MP spectroscopic analysis tool was developed to facilitate a quick and accurate analysis of existing MP samples.