Correlation Spectra Research Articles

The inverse correlation between robustness and sensitivity to autoregulation in two-component systems

Two-component systems (TCS) are signal transduction systems in bacteria and many other organisms that relay the sensory signal to genetic components. TCS consist of two proteins: a histidine kinase and a response regulator that the histidine kinase activates. This seemingly simple machinery can generate complex regulatory dynamics that enables the level of gene expression that matches the input signal: many TCS response regulators act on their own genes as transcription factors, resulting in a positive autoregulation mechanism. This regulation, in return, modulates the transcription factor activity as a function of the input signal. Positive autoregulation does not necessarily result in positive feedback. Sensitivity to autoregulation is quantified as the output level amplification resulting from the positive autoregulation mechanism. Another structural property of these systems is formally characterized as “robustness”: in a robust TCS, the output of the system is solely a function of the input signal. Thus, a robust TCS remains insensitive to fluctuations in the concentrations of its protein components and, this way, maintains the precision in the output transcription factor activity in response to input stimulus. In this paper, we show with a formal model that TCS operate on a spectrum of inverse correlation between robustness and sensitivity to autoregulation. Our model predicts that the modulation by positive autoregulation is a function of loss in TCS robustness, for example, by spontaneous dephosphorylation of the histidine kinase. Consequently, the loss in robustness provides a proportional modulation by positive autoregulation to widen the response range with a scaled amplification of the output. At the other end of the spectrum, in the presence of a strictly robust TCS machinery, amplification of the transcription factor activity by autoregulation is diminished. We show that our results are in agreement with published experimental results. Our results suggest that these TCS evolve to converge at a trade-off between robustness and positive autoregulation.

Nightshift: A Python program for plotting simulated NMR spectra from assigned chemical shifts from the Biological Magnetic Resonance Data Bank.

Nuclear magnetic resonance (NMR) provides site specific information on local environments through chemical shifts. NMR is widely used in the study of proteins, ranging from determination of three-dimensional (3D) structures to characterizing dynamics and binding of small molecules and other proteins or ligands. Assigned chemical shift data for the atoms within proteins is a treasure trove of information that can facilitate a broad range of biochemical and biophysical studies. The Biological Magnetic Resonance Data Bank (BMRB) is a publicly accessible database that contains a large number of assigned chemical shifts; however, translating this wealth of knowledge into a practical application is not straightforward. Herein we present nightshift: a Python command line utility and library for plotting simulated two-dimensional (2D) and 3D NMR spectra from assigned chemical shifts in the BMRB. This tool allows users to simulate routinely collected amide and methyl fingerprint spectra, backbone triple-resonance assignment spectra, and user-defined custom correlations, including ones that do not necessarily correspond to published experiments. This tool enables experienced NMR spectroscopists, those learning the craft, and interested scientists seeking to utilize NMR the ability to preview or examine a wide range of spectra for proteins whose assignments are deposited in the BMRB, irrespective of whether those experiments have been executed or reported. The tool applies equally to folded and intrinsically disordered proteins, limited only by the existence of a BMRB deposition. The features of nightshift are described along with applications that illustrate the ease with which complicated correlation spectra and binding events can be simulated.

Analysis of the Structural Aspects of Tannin-Based Adhesives by 2D-NMR.

We developed non-toxic, harmless adhesives composed of all-natural and renewable resources, of which one was composed of tannin and gelatin, which unfortunately was lacking water resistance, and the other of tannin and ε-poly-l-lysine. In this study, we analyzed the chemical structures of these adhesives by two-dimensional nuclear magnetic resonance (2D-NMR) to explain the difference in water-resistance of the two glues. The results showed that only one proton was left in the benzene ring of tannin after mixing. This suggests that the amino group of the protein was directly attached to the benzene ring by a Michael addition-type reaction, and not to the hydroxyl group. In addition, the heteronuclear multiple bond correlation spectrum of the tannin-poly-l-lysine compound indicated that the hydroxyl groups of the tannin oxidized, suggesting the improvement of its water resistance.

Fault diagnosis of rolling element bearing using ACYCBD based cross correlation spectrum

Rolling element bearings are crucial components in all kinds of rotating machinery. Its fault detection is of great importance, as it ensures the performance of the whole machine. Periodic transient impulses caused by bearing defects are usually submerged in strong background noise which poses a challenge for effective fault feature extraction. To detect bearing faults reliably, a new fault feature extraction method is presented. First, the adaptive maximum second-order cyclostationary blind deconvolution is utilized to recover bearing fault-related impulses, while the optimal filter length is chosen based on the harmonic significance index which quantifies the diagnostic information contained in a deconvoluted signal. Second, cross-correlation is calculated between the teager energy operator and the envelope of the deconvoluted signal to further eliminate the irrelevant noise. Finally, fast fourier transform is employed to acquire the cross-correlation spectrum and the fault features can be extracted successfully. The performance of the proposed method is verified on both simulation signals and experimental signals acquired from a test rig. The superior abilities of noise reduction and fault detection are shown clearly when compared with some traditional method.

Spontaneous Intradural Cerebral Artery Dissection: Spectrum of Clinical Presentations and Correlation with Angiographic Findings

Spontaneous Intradural Cerebral Artery Dissection: Spectrum of Clinical Presentations and Correlation with Angiographic Findings

Solid-State NMR Studies of the Succinate-Acetate Permease from Citrobacter Koseri in Liposomes and Native Nanodiscs

The succinate-acetate permease (SatP) is an anion channel with six transmembrane domains. It forms different oligomers, especially hexamers in the detergent as well as in the membrane. Solid-state NMR studies of SatP were carried out successfully on SatP complexes by reconstructing the protein into liposomes or retaining the protein in the native membrane of E. coli., where it was expressed. The comparison of 13C-13C 2D correlation spectra between the two samples showed great similarity, opening the possibility to further study the acetate transport mechanism of SatP in its native membrane environment. Solid-state NMR studies also revealed small chemical shift differences of SatP in the two different membrane systems, indicating the importance of the lipid environment in determining the membrane protein structures and dynamics. Combining different 2D SSNMR spectra, chemical shift assignments were made on some sites, consistent with the helical structures in the transmembrane domains. In the end, we pointed out the limitation in the sensitivity for membrane proteins with such a size, and also indicated possible ways to overcome it.

Genetic spectrum of familial hypercholesterolemia and correlations with clinical expression: Implications for diagnosis improvement.

Familial hypercholesterolemia (FH) is the most common genetic disease caused by variants in LDLR, APOB, PCSK9 genes; it is characterized by high levels of LDL‐cholesterol and premature cardiovascular disease. We aim to perform a retrospective analysis of a genetically screened population (528 unrelated patients—342 adults and 186 children) to evaluate the biochemical and clinical correlations with the different genetic statuses. Genetic screening was performed by traditional sequencing and some patients were re‐analyzed by next‐generation‐sequencing. Pathogenic variants, mainly missense in the LDLR gene, were identified in 402/528 patients (76.1%), including 4 homozygotes, 17 compound heterozygotes and 1 double heterozygotes. A gradual increase of LDL‐cholesterol was observed from patients without pathogenic variants to patients with a defective variant, to patients with a null variant and to patients with two variants. Six variants accounted for 51% of patients; a large variability of LDL‐cholesterol was observed among patients carrying the same variant. The frequency of pathogenic variants gradually increased from unlikely FH to definite FH, according to the Dutch Lipid Clinic Network criteria. Genetic diagnosis can help prognostic evaluation of FH patients, discriminating between the different genetic statuses or variant types. Clinical suspicion of FH should be considered even if few symptoms are present or if LDL‐cholesterol is only mildly increased.

The Effect of Trifluoroacetic Acid on Molecular Weight Determination of Polyesters: An in Situ NMR Investigation

Due to the poor solubility of aromatic polyesters in common organic solvents, trifluoroacetic acid is usually used as a co-solvent to increase their solubility for characterizations. However, only few works have reported the side reactions induced by it. We present here the application of in-situ 1H NMR techniques to explore its effect on the hydroxyl end-groups, which are usually used for the molecular weight determination of polyesters by end-group estimation method. Using bis(2-hydroxyethyl) terephthalate (BHET) as model compound, 1H quantitative NMR results show the peak integration of hydroxyethyl end-groups decreased with time via a pseudo-first-order kinetics in d-trifluoroacetic acid/d-chloroform mixture solvent (1:10 in volume). This is due to the esterification of hydroxyethyl groups with trifluoroacetic acid, revealed by the 1H-13C gradient-enhanced heteronuclear multiple bond correlation (gHMBC) spectrum. The mixtures of dimethyl terephthalate and BHET with different molar ratio were used to represent poly(ethylene terephthalate) (PET) with different degree of polymerization, and the effect of trifluoroacetic acid on the estimation of hydroxyethyl groups and subsequent molecular weight determination of polyesters was studied. Our results show that if a relative error of 5% is allowed, the NMR measurements must be finished within 1.3 h of solution preparation at 25 C in the mixture solvent. The results were confirmed in PET sample, while in poly(ethylene adipate), the obtained esterifaction constant is faster that those in aromatic system. The results can be applied to other polymer systems with alcohol functionalized groups, and used as a guideline for the characterization of polyesters and polyethers by end-group estimation method.

Cooperative Self-Assembly Driven by Multiple Noncovalent Interactions: Investigating Molecular Origin and Reassessing Characterization.

Cooperative interactions play a pivotal role in programmable supramolecular assembly. Emerging from a complex interplay of multiple noncovalent interactions, achieving cooperativity has largely relied on empirical knowledge. Its development as a rational design tool in molecular self-assembly requires a detailed characterization of the underlying interactions, which has hitherto been a challenge for assemblies that lack long-range order. We employ extensive one- and two-dimensional magic-angle-spinning (MAS) solid-state NMR spectroscopy to elucidate key structure-directing interactions in cooperatively bound aggregates of a perylene bisimide (PBI) chromophore. Analysis of 1H–13C cross-polarization heteronuclear correlation (CP-HETCOR) and 1H–1H double-quantum single-quantum (DQ-SQ) correlation spectra allow the identification of through-space 1H···13C and 1H···1H proximities in the assembled state and reveals the nature of molecular organization in the solid aggregates. Emergence of cooperativity from the synergistic interaction between a stronger π-stacking and a weaker interstack hydrogen-bonding is elucidated. Finally, using a combination of optical absorption, circular dichroism, and high-resolution MAS NMR spectroscopy based titration experiments, we investigate the anomalous solvent-induced disassembly of aggregates. Our results highlight the disparity between two well-established approaches of characterizing cooperativity, using thermal and good solvent-induced disassembly. The anomaly is explained by elucidating the difference between two disassembly pathways.

Evaluating the spectrum-effect profiling and pharmacokinetics of Tieshuang Anshen Prescription with better sedative-hypnotic effect based on Fe2+ than Hg2+

Although Zhusha Anshen Pill (ZSASP) is a commonly used traditional prescription for insomnia, the safety of cinnabar in the formula has always been controversial since its initial application in medical fields. Here, we developed a new prescription, Tieshuang Anshen Prescription (TSASP), by improving ZSASP with Fe2+ instead of Hg2+. Besides, TSASP was further optimized by establishing and testing the HPLC fingerprint and its sedative-hypnotic effect of formulas with different compatibility ratios and performing correlation spectrum analysis. The safety of TSASP was also evaluated by HE staining of liver and kidney. In addition, a validated and robust UHPLC-MS/MS method was established to demonstrate the pharmacokinetic characteristics of berberine, palmatine, jatrorrhizine, ligustilide, catalpol, loganin, liquiritin and liquiritigenin after oral administration of TSASP. Our study originally provides a new non-toxic prescription, TSASP, with better sedative-hypnotic effect in comparison with ZSASP, revealing that Fe2+ could replace Hg2+ to eliminate its toxicity and play a sedative role. Meanwhile, we believe that our pharmacokinetics results may contribute valuable reference to both TSASP’s specific mechanism of action and its further clinical efficacy and effectiveness research.

Few-body nature of Kondo correlated ground states

The quenching of degenerate impurity states in metals generally induces a long-range correlated quantum state known as the Kondo screening cloud. While a macroscopic number of particles clearly take part in forming this extended structure, assessing the number of truly entangled degrees of freedom requires a careful analysis of the relevant many-body wavefunction. For this purpose, we examine the natural single-particle orbitals that are eigenstates of the single-particle density (correlation) matrix for the ground state of two quantum impurity problems: the interacting resonant level model (IRLM) and the single impurity Anderson model (SIAM). As a simple and general probe for few-body versus many-body character we consider the rate of exponential decay of the correlation matrix eigenvalues towards inactive (fully empty or filled) orbitals. We find that this rate remains large in the physically most relevant region of parameter space, implying a few-body character. Genuine many-body correlations emerge only when the Kondo temperature becomes exponentially small, for instance near a quantum critical point. In addition, we demonstrate that a simple numerical diagonalization of the few-body problem restricted to the Fock space of the most correlated orbitals converges exponentially fast with respect to the number of orbitals, to the true ground state of the IRLM. We also show that finite size effects drastically affect the correlation spectrum, shedding light on an apparent paradox arising from previous studies on short chains.

Extramedullary Manifestations in World Health Organization-Defined Chronic Myelomonocytic Leukemia: Clinical, Molecular and Prognostic Correlates

Background:Chronic myelomonocytic leukemia (CMML) is an aggressive myeloid neoplasm with overlapping myeloproliferative and myelodysplastic features. Extramedullary manifestations (EMM) include splenomegaly, hepatomegaly, lymphadenopathy, leukemia cutis, gingival infiltrates, central nervous system (CNS) and testicular involvement and myeloid sarcomas. We carried out this study to i) define clinical and laboratory correlates of EMM in CMML, ii) to assess the prognostic impact of EMM, and iii) to document survival outcomes.Methods:Four hundred and fifty-two patients with WHO-defined CMML were included in the study. All morphological and cytogenetic assessments at baseline were performed at the Mayo Clinic, MN. Bone marrow (BM) DNA at diagnosis was available in 229 (50%) patients and was subjected to a 29 gene panel next generation sequencing analysis. EMM for the purpose of this study were defined as: palpable splenomegaly, palpable hepatomegaly, palpable lymphadenopathy, clinical/radiological or biopsy proven leukemia cutis, gingival infiltrates, testicular involvement, CNS involvement, and myeloid sarcomas. EMM were included if present either at the time of CMML diagnosis, or within six months of stable disease following diagnosis. Standard statistical tests and measures were utilized.Results:Three hundred and seventy-three (82%) patients had an exam documented at the time of diagnosis, or within six months of diagnosis, and were included in the analysis. The median age was 69 years (range, 18-95), 66% were male and 176 (47%) had a “proliferative CMML phenotype.”1. Clinical correlates:One hundred and nineteen (32%) patients had at least one EMM at diagnosis. This included; palpable splenomegaly 91 (76%), hepatomegaly 48 (40%), lymphadenopathy 19 (15%), leukemia cutis 7 (6%), gingival infiltrates 4 (3%), myeloid sarcomas 2 (2%), and 1 each with testicular and CNS involvement (1%). Thirty two (27%) had non hepatosplenic EMM, 102 (86%) had palpable hepato and/or splenomegaly, whereas 54 (45%) and 11 (9%) had isolated palpable splenomegaly and hepatomegaly. In comparison to CMML patients without EMM, those with, were more likely to be younger (p <0.0001), have a higher leukocyte count (WBC, p <0.0001), higher absolute neutrophil count (ANC, p <0.0001), higher absolute monocyte count (AMC, p <0.0001), have circulating immature myeloid cells (IMC, p <0.0001), have mutations involving ASXL1 (p 0.03), CBL (p 0.04), and CSF3R (p 0.02), lack SF3B1 (p 0.009) and ZRSR2 (p 0.03) mutations and have a higher risk stratification by the Mayo Molecular Model (MMM, p<0.0001) and the GFM model (p=0.004).2. Prognostic impact:At last follow up (median 14 months), 249 (67%) deaths and 69 (18%) leukemic transformations were documented. Median survival (OS) was 13 months for patients with non hepatosplenic EMM, 13.2 months for those with palpable hepatosplenomegaly, and 25 months for those without EMM (Figure 1). On univariate analysis, survival was adversely affected by, male sex (p 0.03), low hemoglobin (p <0.0001), high WBC (p 0.0005), high AMC (p <0.0001), presence of IMC (p 0.002), circulating blast % (p <0.0001), high LDH (p 0.0004), presence of EMM (p <0.0001), palpable hepatosplenomegaly (p=0.0008), leukemia cutis (p=0.02), proliferative CMML phenotype (p <0.0001), adverse cytogenetics (p 0.003), absence of TET2 (p 0.0004) and the presence of DNMT3A (p 0.002), IDH1 (p 0.013), ASXL1 (p 0.03), and Tp53 (p 0.014) mutations. Non-hepatosplenic EMM, palpable lymphadenopathy, CNS, testicular involvement and the presence of myeloid sarcomas did not impact OS. On multivariate analysis, only male sex (p= 0.009, HR 1.6, 95% CI 1.1-2.3), low hemoglobin (p <0.0001, HR 1.74, 95% CI 1.3-2.3), palpable hepatosplenomegaly (p 0.0005, HR 1.8, 95% CI 1.04-2.2), absence of TET2 mutations (p 0.023, HR 0.7, 95% CI 0.5-0.95), and the presence of DNMT3A mutations (p 0.013, HR 2.3, 95% CI 1.2-4.3) retained an independent negative prognostic impact. Palpable hepatosplenomegaly retained prognostic significance when assessed in the context of the MMM (p=0.03) and the GFM (p=0.04) models. EMM had no impact on leukemia-free survival.Conclusion:The current study demonstrates a prognostically-relevant frequent occurrence of hepatosplenomegaly in CMML; the study also provides the spectrum and frequency of extramedullary manifestations and correlations with mutations. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

Discrimination of the fruits of Amomum tsao-ko according to geographical origin by 2DCOS image with RGB and Resnet image analysis techniques

Amomum tsao-ko Crevost et Lemaire is a well-known dietary spice in the world for its unique flavor and medicinal effects. Nevertheless, the geographical origin of A. tsao-ko fruits plays a key role in affecting their aroma of cooking food and medicinal effects. This study attempted to investigate the prospects of using two dimensional correlation spectra (2DCOS) and image analysis methods for tracing the origins of A. tsao-ko fruits. To this goal, the near infrared (NIR) spectra of 439 A. tsao-ko fruits collected from 6 regions were obtained and converted into synchronous and asynchronous 2DCOS images. On this basis, two image analysis methods, including Red-Green-Blue (RGB) image analysis and residual convolutional neural network (Resnet) analysis, were applied for authenticating the geographical origin. The results of two image classification models indicated that synchronous 2DCOS images were more suitable to discriminate the geographical origins of A. tsao-ko fruits than asynchronous 2DCOS images. Furthermore, the comparison of categorized result between two image classification models suggested that Resnet model could not only automatically extract features from raw data but also provide more better discriminate model. Therefore, synchronous 2DCOS images combined Resnet analysis could be used as a reliable method for quality control of spice and herb.

Whole-Brain Imaging of Subvoxel T1-Diffusion Correlation Spectra in Human Subjects.

T1 relaxation and water mobility generate eloquent MRI tissue contrasts with great diagnostic value in many neuroradiological applications. However, conventional methods do not adequately quantify the microscopic heterogeneity of these important biophysical properties within a voxel, and therefore have limited biological specificity. We describe a new correlation spectroscopic (CS) MRI method for measuring how T1 and mean diffusivity (MD) co-vary in microscopic tissue environments. We develop a clinical pulse sequence that combines inversion recovery (IR) with single-shot isotropic diffusion encoding (IDE) to efficiently acquire whole-brain MRIs with a wide range of joint T1-MD weightings. Unlike conventional diffusion encoding, the IDE preparation ensures that all subvoxel water pools are weighted by their MDs regardless of the sizes, shapes, and orientations of their corresponding microscopic diffusion tensors. Accordingly, IR-IDE measurements are well-suited for model-free, quantitative spectroscopic analysis of microscopic water pools. Using numerical simulations, phantom experiments, and data from healthy volunteers we demonstrate how IR-IDE MRIs can be processed to reconstruct maps of two-dimensional joint probability density functions, i.e., correlation spectra, of subvoxel T1-MD values. In vivo T1-MD spectra show distinct cerebrospinal fluid and parenchymal tissue components specific to white matter, cortical gray matter, basal ganglia, and myelinated fiber pathways, suggesting the potential for improved biological specificity. The one-dimensional marginal distributions derived from the T1-MD correlation spectra agree well with results from other relaxation spectroscopic and quantitative MRI studies, validating the T1-MD contrast encoding and the spectral reconstruction. Mapping subvoxel T1-diffusion correlations in patient populations may provide a more nuanced, comprehensive, sensitive, and specific neuroradiological assessment of the non-specific changes seen on fluid-attenuated inversion recovery (FLAIR) and diffusion-weighted MRIs (DWIs) in cancer, ischemic stroke, or brain injury.

Spectrum of Movement Disorders and Correlation with Functional Status in Children with Cerebral Palsy.

To detail the spectrum of movement disorders (MD) among children with cerebral palsy (CP) and assess impact on functional status. In this cross-sectional study, children with CP were recruited and examined for various MDs. Tone abnormality was assessed using Hypertonia Assessment Tool (HAT), functional status using Gross Motor Function Classification System Expanded and Revised (GMFCS E&R), Manual Ability Classification System (MACS), and Communication Function Classification System (CFCS). These scores were classified into mild-moderate (level I-III)/severe (level IV-V) categories. A total of 113 children (mean age 4.9 ± 3.4 y, 66.4% boys) were enrolled. MDs were noted in 52(46%) children; the most frequent were dystonia (28%), chorea (14%), choreoathetosis (8%). Of 64 children with quadriparetic CP, 27 (42.2%) demonstrated MDs. Of 19 children with hemiparetic CP, 2 (10.5%) had MDs. Of 16 children with dyskinetic CP, 15 (93%) had MDs. Children with dyskinetic CP had significantly higher frequency of MDs (p = 0.001). There was no difference in occurrence of all MDsor dystonia aloneamongst the two categories (mild-moderate/severe) of GMFCS E&R levels, CFCS levels or MACS levels. Although diverse MDs occur frequently in CP, these do not correlate with the broad functional status of the child. The study is limited by small sample size.

Xylan Structure and Dynamics in Native Brachypodium Grass Cell Walls Investigated by Solid-State NMR Spectroscopy.

The polysaccharide composition and dynamics of the intact stem and leaf cell walls of the model grass Brachypodium distachyon are investigated to understand how developmental stage affects the polysaccharide structure of grass cell walls. 13C enrichment of the entire plant allowed detailed analysis of the xylan structure, side-chain functionalization, dynamics, and interaction with cellulose using magic-angle-spinning solid-state NMR spectroscopy. Quantitative one-dimensional 13C NMR spectra and two-dimensional 13C–13C correlation spectra indicate that stem and leaf cell walls contain less pectic polysaccharides compared to previously studied seedling primary cell walls. Between the stem and the leaf, the secondary cell wall-rich stem contains more xylan and more cellulose compared to the leaf. Moreover, the xylan chains are about twofold more acetylated and about 60% more ferulated in the stem. These highly acetylated and ferulated xylan chains adopt a twofold conformation more prevalently and interact more extensively with cellulose. These results support the notion that acetylated xylan is found more in the twofold screw conformation, which preferentially binds cellulose. This in turn promotes cellulose–lignin interactions that are essential for the formation of the secondary cell wall.

A general strategy for the structural determination of carbohydrates by multi-dimensional NMR spectroscopies

Two-dimensional NMR spectroscopies are one of the most frequently used techniques for the structural determination of carbohydrates. However, the data analysis is challenging because of the signal overlap in the 1H homonuclear correlation spectra. We attempted to explore a general strategy for the structural determination of carbohydrates by combined multi-dimensional spectroscopies. The strategy was applied to a human milk oligosaccharide lacto-N-difucohexaose I, that has been previously studied by conventional two-dimensional NMR spectroscopy. Assignment of the intra-residue resonances of the hexasaccharide using the three-dimensional spectrum was straightforward. Consequently, data analysis of the multi-dimensional spectra was significantly simplified, leading to a quicker determination of the intra- and inter-residue connections in the hexasaccharide. Application of the NMR strategy to chondroitin sulfate from bovine cartilage revealed two repeating disaccharide regions of the A and C units of chondroitin sulfate, indicating the high potential of this technique for the structural determination of complex polysaccharides.

Development and validation of time‐domain 1H‐NMR relaxometry correlation for high‐throughput phenotyping method for lipid contents of lignocellulosic feedstocks

AbstractThe bioenergy crops such as energycane, miscanthus, and sorghum are being genetically modified using state of the art synthetic biotechnology techniques to accumulate energy‐rich molecules such as triacylglycerides (TAGs) in their vegetative cells to enhance their utility for biofuel production. During the initial genetic developmental phase, many hundreds of transgenic phenotypes are produced. The efficiency of the production pipeline requires early and minimally destructive determination of oil content in individuals. Current screening methods require time‐intensive sample preparation and extraction with chemical solvents for each plant tissue. A rapid screen will also be needed for developing industrial extraction as these crops become available. In the present study, we have devised a proton relaxation nuclear magnetic resonance (1H‐NMR) method for single‐step, non‐invasive, and chemical‐free characterization of in‐situ lipids in untreated and pretreated lignocellulosic biomass. The systematic evaluation of NMR relaxation time distribution provided insight into the proton environment associated with the lipids in the biomass. It resolved two distinct lipid‐associated subpopulations of proton nuclei that characterize total in‐situ lipids into bound and free oil based on their “molecular tumbling” rate. The T1T2 correlation spectra also facilitated the resolution of the influence of various pretreatment procedures on the chemical composition of molecular and local 1H population in each sample. Furthermore, we show that hydrothermally pretreated biomass is suitable for direct NMR analysis unlike dilute acid and alkaline pretreated biomass which needs an additional step for neutralization.

On the use of radio-frequency offsets for improving double-quantum homonuclear dipolar recoupling of half-integer-spin quadrupolar nuclei.

Detecting proximities between nuclei is crucial for atomic-scale structure determination with nuclear magnetic resonance (NMR) spectroscopy. Different from spin-1/2 nuclei, the methodology for quadrupolar nuclei is limited for solids due to the complex spin dynamics under simultaneous magic-angle spinning (MAS) and radio-frequency irradiation. Herein, the performances of several homonuclear rotary recoupling (HORROR)-based homonuclear dipolar recoupling sequences are evaluated for 27 Al (spin-5/2). It is shown numerically and experimentally on mesoporous alumina that outperforms the supercycled S3 sequence and its pure double-quantum (DQ) (bracketed) version, [S3 ], both in terms of DQ transfer efficiency and bandwidth. This result is surprising since the S3 sequence is among the best low-power recoupling schemes for spin-1/2. The superiority of is thoroughly explained, and the crucial role of radio-frequency offsets during its spin dynamics is highlighted. The analytical approximation of , derived in an offset-toggling frame, clarifies the interplay between offset and DQ efficiency, namely, the benefits of off-resonance irradiation and the trough in DQ efficiency for when the irradiation is central between two resonances, both for spin-1/2 and half-integer-spin quadrupolar nuclei. Additionally, density matrix propagations show that the sequence, applied to quadrupolar nuclei subject to quadrupolar interaction much larger than radio-frequency frequency field, can create single- and multiple-quantum coherences for near on-resonance irradiation. This significantly perturbs the creation of DQ coherences between central transitions of neighboring quadrupolar nuclei. This effect explains the DQ efficiency trough for near on-resonance irradiation, in the case of both cross-correlation and autocorrelation peaks. Overall, this work aids experimental acquisition of homonuclear dipolar correlation spectra of half-integer-spin quadrupolar nuclei and provides theoretical insights towards improving recoupling schemes at high magnetic field and fast MAS.

Geographical discrimination of Boletus edulis using two dimensional correlation spectral or integrative two dimensional correlation spectral image with ResNet

Boletus edulis (B. edulis) is a well-known edible mushroom species in the world due to its high nutritional values. However, its nutritional value varies greatly depending on geographical origins. This study aimed to discriminate the geographical regions of B. edulis by using a novel digital image method based on two dimensional correlation spectra (2DCOS) or integrative two dimensional correlation spectra (i2DCOS). In our research, 106 fruiting bodies of wild-grown B. edulis mushrooms were collected from 2011 to 2014 in 6 geographical regions. We intercepted 1750-400 cm−1 fingerprint regions from their mid-infrared (MIR) spectra, and converted them into 2DCOS or i2DCOS spectra with matlab2017b. Then, a residual convolutional neural network (ResNet) was established with 95 (90%) spectral images. In our model, the discrimination of geographical regions of the Boletus was using directly synchronous 2DCOS, asynchronous 2DCOS or i2DCOS spectral images instead of data matric from these spectra. In the synchronous 2DCOS spectra model, these 95 samples could be correctly classified as their respective regions with 100% accuracy in the train set and 100% accuracy in the test set, and all 11 (10%) samples of external validation set were discriminated correctly. The results indicated that the synchronous 2DCOS spectra model has good discrimination performance, and the new analytical method in this paper can be used for quality control of food, herb and agricultural products.