Peak Width Research Articles

Continuous monitoring of a monoclonal antibody by size exclusion chromatography reveals a correlation between system suitability parameters and column aging

Size exclusion chromatography (SEC) is a foundational analytical method to assess product purity of biological molecules. To ensure accurate and reproducible data that meet regulatory agency standards, it is critical to monitor the chromatographic column with efficient and continuous approaches. In this study, 19 SEC columns (Waters Acquity BEH200) were evaluated using an in-house monoclonal antibody made at Regeneron. System suitability parameters (SSPs) were used to monitor the performance of the SEC assay, including USP resolution, USP plate count, USP tailing factor, asymmetry factor, elution time, peak width, and peak height. A general linear model was built and revealed that elution time, peak width, asymmetry factor, and tailing factor increased with injection number, while peak height, resolution, and plate count decreased. After 1000 injections, tailing factor and peak width increased by more than 10%, while resolution and plate count decreased by more than 10% from their respective starting values.

Biotransformation of Microcrystalline Cellulose from Rice Straw Waste using TGJPC-120 Bacteria and its Characterization

Microcrystalline Cellulose, MCC, is widely used in pharmaceutical, cosmetics, food, and other industries. This study aims to see changes in the properties that occur in MCC from rice straw waste after transformation using TGJPC-120 isolated bacteria from soil. The biotransformation process was carried out in the bacterial culture flask and placed in an incubator shaker for 2 days at 37 °C, at a rate of 100 rpm. The surface morphology of MCC obtained before and after biotransformation was observed by Scanning Electron Microscopy (SEM). The IR-spectrum and Evaluation of Solid State Interaction of MCC were tested by Fourier Transformation Infra Red (FTIR) Spectrophotometer and Differential Scanning Calorimetry (DSC), respectively. Crystalline characteristics of MCC were analyzed by X-Ray Diffraction technique, and identification of TGJPC-120 was carried out by 16S rRNA analysis. The results showed that DSC thermogram of unbiotransformed and biotransformed-MCC showed the changing in peak width from wide to sharper peaks, reduction in the intensity, and shifts in the melting point. Physical interaction occurs during the biotransformation process to produce a new crystalline phase, and there is no chemical interaction between components during the biotransformation process. The relationship between TGJPC-120 bacteria and Pseudomonas rhizosphaerae Strain IH5 was 92% in the BLAST program tracking database which was determined based on the phylogenetic tree. It can be concluded that the characteristics of MCC before and after the transformation process are different. Studies for process optimization are still ongoing at this time.

Implementing reversed-phase and hydrophilic interaction liquid chromatography into the characterization of DTPA-ramucirumab conjugate before radiolabeling

Radioimmunoconjugates represent a promising class of therapeutics and diagnostics. The characterization of intermediate chelator-antibody products, i.e., without the radionuclide, is frequently omitted, bringing significant uncertainty in the radioimmunoconjugate preparation. In the present study, we explored the utility of reversed-phase (RPLC) and hydrophilic interaction (HILIC) liquid chromatography with UV detection to characterize ramucirumab stochastically conjugated with p-SCN-Bn-CHX-A"-DTPA chelator (shortly DTPA). The conjugation was well reflected in RPLC chromatograms, while chromatograms from HILIC were significantly less informative. RPLC analyses at the intact level confirmed that the conjugation resulted in a heterogeneous mixture of modified ramucirumab. Moreover, the RPLC of DTPA-ramucirumab confirmed heterogeneous conjugation of all subunits. The peptide mapping did not reveal substantial changes after the conjugation, indicating that most parts of ramucirumab molecules remained unmodified and that the DTPA chelator was bound to various sites. Eventually, the RPLC method for analysis of intact ramucirumab was successfully applied to online monitoring of conjugation reaction in 1 h intervals for a total of 24 h synthesis, which readily reflected the structural changes of ramucirumab in the form of retention time shift by 0.21 min and increase in peak width by 0.22 min. The results were obtained in real-time, practically under 10 min per monitoring cycle. To the best of our knowledge, our study represents the first evaluation of RPLC and HILIC to assess the quality of intermediates during the on-site preparation of radioimmunoconjugates prior to radiolabeling.

Perencanaan Revetment pada Sebelah Timur Pantai Kuala Jangka Kecamatan Jangka Kabupaten Bireuen

Kuala Jangka Beach is one of the beaches in the village of Jangka Alue, Term District, Bireuen Regency, Aceh Province. Which is a tourist spot and also a fishery area for fishermen. Waves that are high enough to impact the shoreline so that some areas are eroded due to erosion. Therefore, a coastal protection structure is needed, namely a revetment. A revetment is a coastal protection structure that functions to protect the beach from scouring waves to minimize erosion around the coast. The data used in this planning are wind data, bathymetry, and tidal data. Based on the results of the analysis it is known that the dominant wind that occurs is from the east which is equal to 36%, with the greatest speed being 10 knots or 8.65 m/s. The design wave height calculated from the prevailing wind characteristics is 1,699 m. Sedimentation analysis shows that sedimentation at Kuala Term Beach is dominated by longshore sediment transport which reaches 1,360,132.805 m3/year. Revetment construction is calculated using the general revetment planning formula. The revetment was built from the mountain rock. The height of the revetment building is 3 m with a peak width of 1.5 m and the thickness of the revetment guard wall is 1.5 m and the weight of the bag as a protective layer is 0.301 tons. Meanwhile, the height of gaiters for revetment buildings is 0.75 m with a width of 2.5 m.

A protocol for fabrication of polymer monolithic capillary columns and tuning the morphology targeting high-resolution bioanalysis in gradient-elution liquid chromatography.

Polymer monolithic stationary phases are designed as a continuous interconnected globular material perfused by macropores. Like packed column, where separation efficiency is related to particle diameter, the efficiency of monoliths can be enhanced by tuning the size of both the microglobules and macropores. This protocol described the synthesis of poly(styrene-co-divinylbenzene) monolithic stationary phases in capillary column formats. Moreover, guidelines are provided to tune the macropore structure targeting high-throughput and high-resolution monolith chromatography. The versatility of these columns is exemplified by their ability to separate tryptic digests, intact proteins, and oligonucleotides under a variety of chromatographic conditions. The repeatability of the presented column fabrication process is demonstrated by the successful creation of 12 columns in three different column batches, as evidenced by the consistency of retention times (coefficients of variance [c.v.]=0.9%), peak widths (c.v.=4.7%), and column pressures (c.v.=3.1%) across the batches.

The Stokes Shift and Exciton Fine Structure in Strongly Confined CsPbBr3 Perovskite Nanoplatelets.

The Stokes shift is negligible in bulk perovskites but large in two-dimensional (2D) CsPbBr3 perovskites. The issue has attracted a lot of discussion, but it remains controversial. Here, we report the temperature-dependent absorption and photoluminescence (PL) spectra of CsPbBr3 perovskite nanoplatelets (NPLs). We observe a temperature-dependent Stokes shift changing from 26 to 41 meV. This phenomenon was attributed to the exciton fine structure according to the great difference in peak width. The triple bright exciton levels all participate in the absorption process and result in a wide absorption peak, while only the lowest exciton level contributes to photon emission and exhibits a relatively narrow PL peak. The PL decay curves also present the characterization of bright and dark exciton couplings at low temperatures. The splitting of triple bright excitons is induced by the morphology anisotropy of the 2D structure, so the large Stokes shift is proposed to be an intrinsic property of 2D perovskites.

Cryptomelane nanocrystals: Pseudosymmetry causes anisotropic peak broadening in Rietveld refinement

Cryptomelane (□2-xKx)[Mn8O16] is an octahedral molecular sieve with the hollandite framework, a strongly correlated electron system with tunnel structure. Rietveld refinement using powder X-ray diffraction patterns of a nanocrystalline sample was undertaken to assess both structural and morphological details which might be tuned for specific applications. The distribution of peak widths was highly anisotropic but successful refinement of the tetragonal structure could be achieved assuming both grain shape and microstrain anisotropy. The microstrain hypothesis appeared flawed from high uncertainties and correlations and was in conflict with the negative slope of a Williamson-Hall plot. As an alternative, lattice desymmetrization from tetragonal to monoclinic was considered. Comparison of calculated and observed hkl dependence of line broadening confirmed that the pseudosymmetry hypothesis was more appropriate, improving results for both structure and particle shape. This is the first time that lattice desymmetrization was used to explain anisotropic diffraction line broadening, a major issue in nanomaterials where peaks are intrinsically broad and the new model helps to abate correlations which afflict Rietveld refinement in these systems.

Origin of quasi-linear superelasticity at high temperature in Ni–Mn-Ga-Co shape memory alloy

The quasi-linear superelasticity in Ni–Mn-Ga-Co shape memory alloy displays a complete recoverable strain of ∼3% at 473 K for the cubic phase in precursor state. The in-situ neutron diffraction experiments provide the direct evidence on the stress-induced transition from the precursor state to martensite via the continuous variation of lattice parameter and peak width under uniaxial stress field. The anomalous broadening in peak width suggests that the external stress field may trigger very high heterogeneity in lattice distortion for the initial precursor state having randomly-distributed domains with short-range strain ordering prior to the martensitic transformation. The origin of the quasi-linear superelasticity at high temperature is considered as the ruggedness of the local energy landscape. The present investigations provide new insight into the understanding of superelasticity in shape memory alloys.

Ultrapure Green High Photoluminescence Quantum Yield from FAPbBr3 Nanocrystals Embedded in Transparent Porous Films.

Achieving highly transparent and emissive films based on perovskite quantum dots (PQDs) is a challenging task since their photoluminescence quantum yield (PLQY) typically drops abruptly when they are used as building blocks to make a solid. In this work, we obtain highly transparent films containing FAPbBr3 quantum dots that display a narrow green emission (λ = 530 nm, full width at half-maximum (FWHM) = 23 nm) with a PLQY as high as 86%. The method employed makes use of porous matrices that act as arrays of nanoreactors to synthesize the targeted quantum dots within their void space, providing both a means to keep them dispersed and a protective environment. Further infiltration with poly(methyl methacrylate) (PMMA) increases the mechanical and chemical stability of the ensemble and serves to passivate surface defects, boosting the emission of the embedded PQD and significantly reducing the width of the emission peak, which fulfills the requirements established by the Commission Internationale de l'Éclairage (CIE) to be considered an ultrapure green emitter. The versatility of this approach is demonstrated by fabricating a color-converting layer that can be easily transferred onto a light-emitting device surface to modify the spectral properties of the outgoing radiation.

Phase field study on the flexoelectric response of dielectric–ferroelectric multilayers

We report a theoretical modeling of the flexoelectric response of dielectric–ferroelectric (DE–FE) multilayers based on phase field simulations in the framework of the Landau–Ginzburg–Devonshire (LGD) theory. The correlation between negative capacitance and flexoelectric response is revealed, and the single-domain and multi-domain models are compared. It shows that the dielectric layers drive the ferroelectric layer into a negative capacitance regime, and the flexoelectric response of the multilayer is maximal when the negative capacitance of the ferroelectric layer has a minimal absolute value. Moreover, the flexoelectric response peak will be shifted to a lower temperature by increasing the thickness of dielectric layer, indicating a possibility of achieving a stronger flexoelectric response at room temperature compared with that of pure ferroelectric. However, while the single-domain model shows that the flexoelectric response peak is simply shifted to a lower temperature with near constant peak value and width, the multi-domain model reveals a significant suppressing of the flexoelectric peak by the dielectric layer. This is attributed to the formation of the vortex domain state, which eases the depolarization effect and leads to large absolute value of negative capacitance of the ferroelectric layer. Our work provides new insights into flexoelectricity in ferroelectric heterostructures.

Zero-energy states in graphene quantum dot with wedge disclination

We show that wedge disclination affects the density of states for fermions that are electrostatically confined in graphene quantum dots. By considering a magnetic flux and solving the Dirac equation, we determine the eigenspinors. These are used for large arguments to derive an approximate scattering matrix, which allows us to get the density of states. Under various conditions, it is found that the density of states exhibits several resonance peaks. In particular, it is shown that the wedge disclination is able to change the amplitude, width, and positions of resonance peaks.

Effects of framework dopants on luminescent properties of red nitride phosphors via band structure modelling

Currently, researchers have been able to manipulate the luminescent properties and thermal stability of nitride red phosphor Sr2Si5N8:Eu2+ through rare earth doping. However, there is limited research on the doping of its framework. This work investigated the crystal structure, band structure, and luminescence properties of Sr2Si5N8: Eu2+ and its framework doped systems. We selected B, C, and O as doping elements because the corresponding formation energies of these elements doped structures are relatively low. Then, we calculated the band structures of various doped systems in both the ground and excited states. This analysis aimed to investigate their luminescent properties using the configuration coordinate diagram. The results show that doping with B, C, or O has minimal effect on the emission peak width. The thermal quenching resistance of the B- or C-doped system was enhanced due to the increased energy differences between the 5d energy level of the electron-filled state in the excited state and the bottom of the conduction band, compared to the undoped system. However, the thermal quenching resistance of the O-doped system varies depending on the position of the silicon vacancy. The work indicates that framework doping can also improve the thermal quenching resistance of phosphors besides rare earth ions doping.

Properties of hydrated poly(2-methoxyethyl acrylate) observed by 13C-nuclear magnetic resonance spectroscopy

It is well-known that poly(2-methoxyethyl acrylate) (PMEA) exhibits excellent blood compatibility and various investigations have examined the underlying mechanism of this compatibility in terms of the water structure in PMEA and/or inherent PMEA properties. However, information regarding the dynamic properties of the PMEA remains limited. This study was performed to clarify the effect of water molecules on the structure and dynamic properties of hydrated PMEA by comparing dry PMEA using temperature-variable 13C nuclear magnetic resonance spectroscopy (13C-NMR) with a solution probe at 15 –45 °C. Hydration changed the chemical shift values of the four carbons in the PMEA side chain (−COOCH2 CH2OCH3). Investigations of spin-lattice relaxation times and resonance peak widths showed that hydration increased PMEA mobility and the side chain mobility markedly changed at approximately 30 °C, especially in dry PMEA.

Assessment of residual strain in laser shock peened additive manufactured Inconel 718 using synchrotron X-ray diffraction

The through-thickness residual strain profile due to laser shock peening (LSP) of an additively-manufactured IN718 sample is shown for the first time. The results provide tantalising insight into the potential of fatigue life extension of additive-manufactured samples using LSP. Residual strains were measured in as-manufactured and peened samples using state-of-the-art synchrotron radiation. Significant beneficial compressive in-plane residual strains, extending to 1.0 mm depth, were observed due to the peening process. No phase changes were observed due to LSP. A periodic strain variation was observed arising from the layer-by-layer manufacturing strategy of the samples. The peened sample showed no increase in diffraction peak width in the near-surface regions. This is contrary to reported studies using wrought laser shock peened alloys and suggests less grain disruption in additively-manufactured peened samples. The results are timely given a current drive to adopt additive-manufacturing for a step-change in efficiency of aero-engine component production.

Measurement report: Atmospheric aging of combustion-derived particles – impact on stable free radical concentration and its ability to produce reactive oxygen species in aqueous media

Abstract. Environmentally persistent free radicals (EPFRs) are a pollutant found on fine atmospheric particulate matter (PM2.5), particularly on PM2.5 formed from combustion processes. EPFRs are organic radicals that can endure in the environment for days to years. Interest in the toxicity of EPFRs has increased significantly in recent years, as it has been shown to have substantial ability to form reactive oxygen species (ROS), but little is known about how its characteristics change as PM2.5 ages in the atmosphere. Here, we exposed newly produced hexane-generated soot to simulated sunlight for 24 h. Changes to the EPFR characteristics of the particles were measured by electron paramagnetic resonance (EPR) spectroscopy. The soot was then added to water, and a second exposure to light was used to measure hydroxyl radical (OH) formation from both photoaged and dark-aged soot. There were no changes to EPFR characteristics (spin concentration, g factor, peak width, or lineshape) due to the exposure to simulated sunlight; however, the soot's ability to form OH was greatly reduced by photoaging. Photoaged soot resulted in an almost 60 % reduction in OH formation over soot which had been aged in the dark for the same amount of time.

Theoretical study of elastic electron scattering by zinc atoms in the framework of relativistic optical potential model

A theoretical study of integral and differential cross sections as well as of spin-polarization effects is reported for elastic electron scattering by zinc atoms at collision energies up to 3 keV. It has been shown that a P-wave shape resonance appears in the low-energy range of the integral cross sections. Its energy is about 0.19 and 0.20 eV, while its width is about 0.309 and 0.356 eV for the j = 3/2 and j = 1/2 total angular momentum of the electron, respectively. The differential cross sections of scattering and the Sherman-functions S(E,θ) are computed by the parameter-free complex optical potential method. The calculated data are in a good overall agreement with the available experimental and theoretical data in the literature. The energy and angular positions have been located for five critical minima in the differential cross sections. The low-energy minimum is located at [6.63 eV; 102.34°], while the high-energy minimum is at [347.53 eV; 124.11°]. Ten points for the scattered electrons' total spin-polarization (S=±1) have been found in the vicinity of the critical minima along with the energy and the angular widths of the spin-polarization peaks (where |S|≥0.9).

Study of the High-Efficiency Ejecting-Explosion EDM of SiCp/Al Composite.

SiCp/Al composites have excellent physical properties and are widely used in aerospace and other fields. Because of their poor machinability, they are often machined by non-traditional machining methods such as electrical discharge machining (EDM). In the process of EDM, due to the "shielding" effect of the reinforced particles of SiC, the local ejection force is low during the processing process, and it is difficult to throw the reinforced particles smoothly, which ultimately leads to a low material removal rate and poor surface quality. In this paper, a high-low-voltage composite ejecting-explosion EDM power supply is developed to explore the explosive effect of reinforced particles in the ejecting-explosion EDM process and the unique process law of the explosion process. The experiment platform uses self-developed CNC machining machine tools based on an ejecting-explosive EDM power supply, and the influence of a detonation-increasing wave on the processing of SiCp/Al composites with different volume fractions was studied by changing four factors: the open-circuit voltage difference, pulse current difference, pulse phase difference, and pulse width difference of the back wave behind the step front. The material removal rate and surface roughness were measured. The research results showed that the material removal rate could be increased to 164.63%, and the material surface roughness could be increased to 30.03% by adjusting the high and low pulse current difference from 1 A to 8 A. When the voltage difference between high and low wave (HLW) pulses increases from 40 V to 120 V, the material removal rate can be increased to 150.39%, and the material surface roughness can be increased to 20.49%. The material removal rate increases with the increase in pulse phase difference and open-circuit voltage difference. With the increase in peak current difference and pulse width difference, the material removal rate becomes faster at first and then slower. The surface roughness of materials increases with the growth of open-circuit voltage difference, peak current difference, pulse width difference, and pulse phase difference.

Capillary electrophoresis-mass spectrometry as a tool for Caenorhabditis elegans metabolomics research

IntroductionPolar metabolites in Caenorhabditis elegans (C. elegans) have predominantly been analyzed using hydrophilic interaction liquid chromatography coupled to mass spectrometry (HILIC-MS). Capillary electrophoresis coupled to mass spectrometry (CE-MS) represents another complementary analytical platform suitable for polar and charged analytes.ObjectiveWe compared CE-MS and HILIC-MS for the analysis of a set of 60 reference standards relevant for C. elegans and specifically investigated the strengths of CE separation. Furthermore, we employed CE-MS as a complementary analytical approach to study polar metabolites in C. elegans samples, particularly in the context of longevity, in order to address a different part of its metabolome.MethodWe analyzed 60 reference standards as well as metabolite extracts from C. elegans daf-2 loss-of-function mutants and wild-type (WT) samples using HILIC-MS and CE-MS employing a Q-ToF-MS instrument.ResultsCE separations showed narrower peak widths and a better linearity of the estimated response function across different concentrations which is linked to less saturation of the MS signals. Additionally, CE exhibited a distinct selectivity in the separation of compounds compared to HILIC-MS, providing complementary information for the analysis of the target compounds. Analysis of C. elegans metabolites of daf-2 mutants and WT samples revealed significant alterations in shared metabolites identified through HILIC-MS, as well as the presence of distinct metabolites.ConclusionCE-MS was successfully applied in C. elegans metabolomics, being able to recover known as well as identify novel putative biomarkers of longevity.

Distinct cerebral small vessel disease impairment in early-and late-onset Alzheimer's disease.

This study investigated cerebral small vessel disease (CSVD) damage patterns in early-onset and late-onset Alzheimer's disease (EOAD and LOAD) and their effects on cognitive function. This study included 93 participants, 45 AD patients (14 EOAD and 31 LOAD), and 48 normal controls (13 YNC and 35 ONC) from the ADNI database. All participants had diffusion tensor imaging data; some had amyloid PET and plasma p-tau181 data. The study used peak width of skeletonized mean diffusivity (PSMD) to measure CSVD severity and compared PSMD between patients and age-matched controls. The effect of age on the relationship between PSMD and cognition was also examined. The study also repeated the analysis in amyloid-positive AD patients and amyloid-negative controls in another independent database (31 EOAD and 38 LOAD), and the merged database. EOAD and LOAD showed similar cognitive function and disease severity. PSMD was validated as a reliable correlate of cognitive function. In the ADNI database, PSMD was significantly higher for LOAD and showed a tendency to increase for EOAD; in the independent and merged databases, PSMD was significantly higher for both LOAD and EOAD. The impact of PSMD on cognitive function was notably greater in the younger group (YNC and EOAD) than in the older group (ONC and LOAD), as supported by the ADNI and merged databases. EOAD has less CSVD burden than LOAD, but has a greater impact on cognition. Proactive cerebrovascular prevention strategies may have potential clinical value for younger older adults with cognitive decline.

UV Photoluminescence Microscopy of Individual ZnO Nanostructured Clusters

Ultraviolet (UV) photoluminescence (PL) spectra were acquired from individual nanostructured ZnO clusters less than 1 μm in size. The nanostructured clusters were formed by aggregation of a small number of nanoparticles. This analysis employed a microscopy apparatus specially designed for PL assessments of nanostructures at UV wavelengths with a spatial resolution of 0.395 μm. Atomic force microscopy was also employed to ascertain the sizes and morphologies of the nanostructured clusters. The ZnO samples were prepared by laser ablation in liquid (LAL) and comprised spherical, rhomboid, or gel-coated particles. PL emissions originating from free excitons (FX), FX phonon replicas, and defects were observed. The FX peak widths and positions were found to vary (with positions from 3.30 to 3.36 eV), suggesting that a range of particle sizes and morphologies was obtained from the LAL process. FX peaks at higher energies exhibited greater widths as a consequence of a quantum size effect originating from the crystallites comprising the nanostructured clusters. The rhomboid particles showed less-intense emissions related to defects compared with the other two types while also exhibiting the least intense emissions related to FX phonon replicas. This work also examined the mechanism by which nanoparticles were produced by LAL on the basis of the spectroscopic data. The information presented herein is expected to assist in the design and fabrication of semiconductor nanoparticles for future nanotechnology applications.