In recent years, the rotational Doppler effect (RDE) has been widely used in rotational motion measurement. However, the performance of existing detection systems based on the RDE are generally limited by the drastic reduction of signal-to-noise ratio (SNR) due to the influence of atmospheric turbulence, partial obscuration of the vortex beam (VB) during propagation, and misalignment between the optical axis of VB and the rotational axis of the object, which poses a challenge for practical applications. In this paper, we proposed a coherent detection method of the RDE measurement based on triple Fourier transform. First, the weak RDE signal in backscattered light is amplified by using the balanced homodyne detection method, and the amplified signal still retains the same characteristic of severe broadening in the frequency domain as the original signal. Furthermore, we proposed the triple Fourier transform to extract the broadened RDE frequency shift signal after the coherent amplification. The proposed method significantly improves the SNR of RDE measurement and facilitates the accurate extraction of rotational speed, which helps to further improve the RDE detection range and promote its practical application.
Clusters showing a giant magnetocaloric effect (MCE) are of interest as molecular coolants for magnetic refrigeration. Herein, we report two heterometallic clusters, denoted as Gd152Ni14@Cl24 and Sm152Ni8, just to highlight their inorganic core motifs, obtained by ligand-controlled co-hydrolysis of Ni2+ and Ln3+ (Ln = Gd, Sm) in the presence of N-(2-hydroxyethyl)iminodiacetic acid (H2HEIDA). Both clusters display fascinating cubic Tinkertoy-like structures, with the core motifs being built of multiple metallic shells of Platonic and Archimedean polyhedra. The isothermal magnetic entropy changeâa direct measurement of MCEâwas determined to be 52.65 J·kg-1·K-1 at 2.5 K and 7.0 T for the Gd-containing cluster; this value is the highest known for any molecular clusters so far reported.
Herein the synthesis, structural characterization, and magnetic properties of a Pr(IV) complex [Pr(OSiPh3)4(L)] (1, L = 4,4'-dimethoxy-2,2'-bipyridine) are reported. The stability of the Pr(IV) complex significantly enhanced with the use of the bidentate ligand L. Slow magnetic relaxation was observed at low temperatures, indicating that the complex may be the first single-ion magnet with a tetravalent lanthanide ion being the magnetic center.
Lanthanide complexes with judiciously designed ligands have been extensively studied for their potential applications as single-molecule magnets. With the influence of ligands on their magnetic properties generally established, recent research has unearthed certain effects inherent to site differentiation due to the different types and varying numbers of substituents on the same ligand platform. Using two new sandwich-type Er(III) complexes with cyclooctatetraenyl (COT) ligands featuring two differently positioned trimethylsilyl (TMS) substituents, namely, [Li(DME)Er(COT1,5-TMS2)2]n (Er1) and [Na(DME)3][Er(COT1,3-TMS2)2] (Er2) [COT1,3-TMS2 and COT1,5-TMS2 donate 1,3- and 1,5-bis(trimethylsilyl)-substituted cyclooctatetraenyl ligands, respectively; DME = 1,2-dimethoxyethane], and with reference to previously reported [Li(DME)3][Er(COT1,4-TMS2)2] (A) and [K(DME)2][Er(COT1,4-TMS2)2] (B), any possible substituent position effects have been explored for the first time. The rearrangement of the TMS substituents from the starting COT1,4-TMS2 to COT1,3-TMS2 and COT1,5-TMS2, by way of formal migration of the TMS group, was thermally induced in the case of Er1, while for the formation of Er2, the use of Na+ in the placement of its Li+ and K+ congeners is essential. Both Er1 and Er2 display single-molecule magnetic behaviors with energy barriers of 170(3) and 172(6) K, respectively. Magnetic hysteresis loops, butterfly-shaped for Er1 and wide open for Er2, were observed up to 12 K for Er1 and 13 K for Er2. Studies of magnetic dynamics reveal the different pathways for relaxation of magnetization below 10 K, mainly by the Raman process for Er1 and by quantum tunneling of magnetization for Er2, leading to the order of magnitude difference in magnetic relaxation times and sharply different magnetic hysteresis loops.
Vortex beams (VBs) with orbital angular momentum have shown great potential in the detection of transverse rotational motion of spatial targets which is undetectable in the classical radar scheme. However, most of the reported rotational Doppler measurements based on VBs can only be realized under ideal experimental conditions. The long-range detection is still a challenge. The detection distance based on rotational Doppler effect (RDE) is mainly limited by the scattered signal's signal-to-noise ratio (SNR). In this work, we investigated the influence of multi-ring vortex beams (MVBs) on the rotational Doppler frequency spectrum of scattered light from an object based on RDE and proposed a method of SNR enhancement of RDE signal. Firstly, different types of MVBs composed of a set of single-ring VBs with the same topological charge and different radii are designed, including multi-ring Laguerre Gaussian beam (MLGB), multi-ring perfect vortex beams (MPVB), and high-order Laguerre Gaussian beam (HLGB). Then, the influence of the number of rings and radial radius interval on the intensity profiles of MVBs and rotational Doppler frequency spectra under aligned and misaligned conditions is studied in detail. And the reasons why different types of MVBs lead to different SNR enhancement effectiveness with the increase of rings are also analyzed theoretically. Finally, proof-of-concept experiments were conducted to verify the effectiveness of the SNR enhancement method for RDE signals. The results showed that the amplitudes of the Doppler spectra generated by the MLGB and MPVB are improved substantially with the increase of rings, but the enhancement effect caused by the former is superior to the latter. The gain of HLGB on the RDE signal is the lowest. This study provides a useful reference for the optimization of rotational Doppler detection systems and may be of great application value in telemetry, long-range communication and optical imaging.
BACKGROUND: Cow's milk protein allergy (CMPA) is one of the most common types of food allergy in infants. Faecal pathogen cultures showed that the positive rate of Clostridium perfringens was more than 30%, which was significantly higher than that for other bacteria. Therefore, it is speculated that Clostridium perfringens colonization may be one of the pathogenetic factors for CMPA in infants. We conducted a real-world evidence study. Infants aged 0-6 months with diarrhoea and mucoid and/or bloody stools were recruited from a large tertiary hospital in China. Faecal pathogen cultures for the detection of Clostridium perfringens were confirmed by flight mass spectrometry, and potential toxin genes were identified using PCR. After 12 months of follow-up, the diagnoses of CMPA and food allergy were recorded. The correlation was assessed by Pearson correlation analysis. RESULTS: In this study, 358 infants aged 0-6 months with gastrointestinal symptoms and faecal pathogen cultures were recruited. A total of 270 (44.07% girls; mean age, 2.78 ± 2.84 months) infants were followed up for 12 months. Overall, the rate of positivity for Clostridium perfringens in faecal pathogen cultures was 35.75% (128/358) in infants aged ≤ 6 months. The earliest Clostridium perfringens colonization was detected within 2 days after birth. The majority of Clostridium perfringens isolates were classified as type C in 85 stool samples. In the Clostridium perfringens-positive group, 48.21% (54/112) of infants were clinically diagnosed with food allergies after 12 months, including 37.5% (42/112) with CMPA, which was significantly higher than that of the negative group, with 7.59% (12/158) exhibiting food allergies and 5.06% (8/158) presenting CMPA (P < 0.0001). Faecal Clostridium perfringens positivity was significantly correlated with CMPA, food allergy, faecal occult blood, faecal white blood cells, antibiotic use, increased peripheral blood platelet counts, and decreased haemoglobin levels (P < 0.0001). CONCLUSIONS: This study demonstrates that intestinal colonization by Clostridium perfringens is common in infants. The majority of Clostridium perfringens isolates are classified as type C. Colonization of the intestine by Clostridium perfringens is associated with the development of CMPA and food allergy in infants.
The optical vortex (OV) carries unique orbital angular momentum (OAM) and experiences a Doppler frequency shift when backscattered from a spinning object. This rotational Doppler effect (RDE) has provided a solution for the non-contact detection of rotating motion. The reported RDE researches mainly use a single OV that generates frequency shifts proportional to its topological charge and has low robustness to light incidence. Here, we show the distinctive RDE of superimposed optical vortex array (SOVA). We analyze the holistic OAM of SOVA which is represented in terms of a superposition of azimuthal harmonics and displays a unique modal gathering effect. In the experiment of RDE, the frequency shift signals of SOVA show a precise mapping to the OAM modes and the modal gathering effect contributes to enhance the amplitude of signals, which has the potential to enhance robustness against non-coaxial incidence. This finding provides a new aspect of RDE and a pioneered example for introducing various SOVAs into rotation detection.
This study aimed to investigate the correlation between hydrogen peroxide (H2O2), small ubiquitin-like modifier molecules (SUMO), and pregnancy outcomes in couples with unexplained infertility (UI) undergoing intrauterine insemination (IUI) treatment. We prospectively collected semen samples from 56 couples with UI and divided the spermatozoa into motile and immotile fractions by density gradient centrifugation (DSC). Immunofluorescence staining was used to examine the immunostaining and localization of nuclear pore complex (NPC), SUMO1, and SUMO2/3 in spermatozoa. We detected H2O2 levels by chemiluminescence methods. We found that H2O2 levels correlated with NPC (neck) (r = 0.400) and NPC (tail) (r = 0.473) in motile sperm fractions. In immotile fractions, H2O2 positively correlated with NPC (tail) (r = 0.431) and SUMO1 (neck) (r = 0.282). Furthermore, the positive NPC (tail) group had a significantly lower live birth rate than the negative NPC group (17.9% = 5/28 vs. 42.9% = 12/28). In conclusion, H2O2 positively correlated with SUMO1 (neck) and NPC (tail) in human spermatozoa. The DSC may partially eliminate defective spermatozoa (positive NPC staining); however, if defective spermatozoa remain in the motile fraction, this scenario is associated with a low live birth rate following IUI treatment.
Hydrogen Peroxide , Infertility , Humans , Female , Pregnancy , Male , Live Birth , Semen , Spermatozoa , Infertility/therapy , Insemination , SUMO-1 Protein
Gadolinium is a special case in spectroscopy because of the near isotropic nature of the 4f7 configuration of the +3 oxidation state. Gd3+ complexes have been studied in several symmetries to understand the underlying mechanisms of the ground state splitting. The abundance of information in Gd3+ spectra can be used as a probe for properties of the other rare earth ions in the same complexes. In this work, the zero-field splitting (ZFS) of a series of Gd3+ pentagonal bipyramidal complexes of the form [GdX1X2(Leq)5]n+ [n = 1, X = axial ligands: Cl-, -OtBu, -OArF5 or n = 3, X = tBuPO(NHiPr)2, Leq = equatorial ligand: Py, THF or H2O] with near fivefold symmetry axes along X1-Gd-X2 was investigated. The ZFS parameters were determined by fitting of room-temperature continuous wave electron paramagnetic resonance (EPR) spectra (at X-, K-, and Q-band) to a spin Hamiltonian incorporating extended Stevens operators compatible with C5 symmetry. Examination of the acquired parameters led to the conclusion that the ZFS is dominated by the B20 term and that the magnitude of B20 is almost entirely dependent on, and inversely proportional to, the donor strength of the axial ligands. Surveying the continuous shape measure and the X1-Gd-X2 angle of the complexes showed that there is some correlation between the proximity of each complex to D5h symmetry and the magnitude of the B65 parameter, but that the deformation of the X1-Gd-X2 angle is more significant than other distortions. Finally, the magnitude of B20 was found to be inversely proportional to the thermal barrier for the reversal of the magnetic moment (Ueff) of the corresponding isostructural Dy3+ complexes.
Two dichloride-bridged dinuclear dysprosium(III) complexes based on salen ligands, namely, [Dy(L1 )(µ-Cl)(thf)]2 (1; H2 L1 =N,N'-bis(3,5-di-tert-butylsalicylidene)phenylenediamine) and [Dy2 (L2 )2 (µ-Cl)2 (thf)2 ]2 (2; H2 L2 =N,N'-bis(3,5-di-tert-butylsalicylidene)ethylenediamine) are reported. These two complexes have two short Dy-O(PhO) bonds that exhibit angles of â¼90° for 1 and â¼143° for 2, leading to clear slow relaxation of the magnetization for 2 and not for 1. Compound 2 has a near-identical core to the recently reported compound [Dy2 (L3 )2 (µ-Cl)2 (thf)2 ] (3; H2 L3 =N-(2-pyridylmethyl)-N,N-bis(2'-hydroxy-3',5'-di-tert-butylbenzyl)amine). The only substantial difference is the relative angle of the two O(PhO) -Dy-O(PhO) vectors, which is collinear in 2 owing to inversion symmetry and â¼68° in 3 due to a molecular C2 axis. It is shown that this subtle structural difference leads to large differences in the dipolar ground states, giving rise to open magnetic hysteresis for 3 and not for 2.
Rotational Doppler effect (RDE), as a counterpart of the conventional linear Doppler effect in the rotating frame, has attracted increasing attention in recent years on rotational object detection. Many previous works have investigated the RDE based on the whole optical vortex field. In this work, we report on the RDE of the partially obstructed optical vortex and the corresponding rotational speed extraction method. Based on the orbital angular momentum (OAM) mode analysis theory, we establish the relationship between the OAM spectrum and the RDE frequency shift of fragmental optical vortex (FOV). The mechanism of the rotational speed extraction is analysed and validated by the numerical simulation and experiments. Further, a dual Fourier transformation method is proposed to accurately obtain the rotational speed which successfully overcomes the problem of the discrete distribution of the RDE signals. Our work may be useful for practical remote sensing based on the optical RDE metrology.
The rotational Doppler effect (RDE) of optical vortex which can be used to detect the rotation speed, has become a well-known phenomenon and a hot topic of research in recent years. However, because the beam axis must be coaxial with the rotational axis of the object, it can only be used to detect cooperative targets in practical application. Here, we provide a novel approach for measuring rotational speed under light non-coaxial incidence relative to the rotating axis that uses the adjacent frequency difference of rotational Doppler shift signals. Theoretically, the rotational Doppler shift is proportional to the OAM mode of the incident beam, and the nature of the OAM carried by each photon is a discrete or quantized quantity under off-axis conditions leading to the discrete distribution of the Doppler shift signals. Experimentally, by extracting the difference between two adjacent Doppler shift signals, the rotating speed of the object can be determined. Based on our method, the rotational speed of the object can be measured precisely without the pre-known information about the position of the rotating axis. Our work supplies a significant complement to the conventional RDE theory and we believe it may promote the realistic application of the optical RDE-based metrology.
The rotational Doppler effect (RDE) of optical vortex beams provides an efficient way to measure the rotational frequency of objects based on rotational Doppler frequency shifts, while the frequency shift signals display a distinct broadening effect when the vortex beam is laterally misaligned with the center of rotation of a planar object. We use a modal decomposition method to reveal the broadening effect and obtain a linear fitting equation between the quantity of signals and lateral misalignments. In an experiment of RDE, the lateral misalignment is extracted from the quantity of signal peaks. The fitting equation is proved to be precise within the uncertainty of ±0.17mm (±2.8% of the vortex beam radius), and the center of rotation is located with an error less than 3.33% of the beam radius. Our work provides a new approach to locate the center of rotation of noncooperative objects, which may be valuable in mechanical manufacturing and optical noncontact metrology.
Aluminum dross (AD) is a waste product produced during aluminum processing and can be used to prepare mullite ceramic materials. However, the research on the preparation of mullite porous ceramics entirely from solid waste is still in the development stage. In this paper, porous mullite ceramics were successfully fabricated using a solid-phase sintering process with AD and different silicon sources (fly ash, silica dust, and gangue) as raw materials. The bulk density, apparent porosity, and compressive strength of the specimens were obtained, and the phase compositions and microstructures of the sintered specimens were measured using XRD and SEM, respectively. The average activation energy of the phase transition of fly ash, silica dust, and gangue as silicon sources were 984 kJ/mol, 1113 kJ/mol, and 741 kJ/mol, respectively. The microstructures of the mullite in the specimens were prisms, random aggregates, and needle-shaped, respectively. The formation of needle-shaped mullite combined with the substrate enhanced the mechanical strength of the porous mullite ceramics. The apparent porosity, density, and compressive strength of the specimens with gangue as the silicon source were 33.13%, 1.98 g/cm3, and 147.84 MPa, respectively, when sintered at 1300 °C for 2 h.
In this study, the hydrolysis behavior and kinetics of AlN in aluminum dross (AD) were investigated in order to better identify the steps controlling the AlN hydrolysis reaction and the factors influencing the hydrolysis rate to enhance the removal efficiency of AlN. The hydrolysis behavior of AlN, including AlN content, phase composition, chemical composition, microstructure, and element distribution, was determined by a leaching test, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and energy dispersive spectroscopy, respectively. The results showed that increasing the leaching liquid-solid ratio as well as the temperature was helpful for the removal efficiency of AlN. When the liquid--solid ratio was 4:1, temperature was 90 °C, and leaching time was 300 min, the removal efficiency of AlN reached 89.05%. The kinetics were described using the unreacted core model, and when the temperature was 30-40, 50-70, and 80-90 °C, the hydrolysis reaction rate of AlN was controlled by boundary layer diffusion, chemical reaction control, and product layer diffusion control, respectively.
The rotational Doppler effect (RDE) provides an efficient way to measure rotational frequency using an optical vortex beam. Crucially, most research based on the RDE just involves a spinning object or a spinning object coupled with a longitudinal velocity along the beam propagation. We analyze the interaction mechanism between optical orbital angular momentum and a spinning object with circular procession and experimentally demonstrate simultaneous measurements of two rotational frequencies. This technique broadens application of the RDE in optical metrology and remote detection of targets with micro-motions.
The fast Raman relaxation process via a virtual energy level has become a puzzle for how to chemically engineer single-molecule magnets (SMMs) with better performance. Here, we use the trifluoromethyl group to systematically substitute the methyl groups in the axial position of the parent bis-butoxide pentapyridyl dysprosium(III) SMM. The resulting complexes-[Dy(OLA )2 py5 ][BPh4 ] (LA =CH(CF3 )2 - 1, CH2 CF3 - 2, CMe2 CF3 - 3)-show progressively enhanced TB hys (@100â Oe s-1 ) from 17â K (for 3), 20â K (for 2) to 23â K (for 1). By experimentally identifying the varied under barrier relaxation energy in the 5-500â cm-1 regime, we are able to identify that the C-F bond related vibration energy of the axial ligand ranging from 200 to 350â cm-1 is the key variant for this improvement. Thus, this finding not only reveals a correlation between the structure and the Raman process but also provides a paradigm for how to apply the vibronic barrier model to analyze multi-phonon relaxation processes in lanthanide SMMs.
Real-time representation of the current performance of structures is an important task for perceiving potential danger in in-service bridges. Methods driven by the multisource sensing data of structural health monitoring systems are an effective way to achieve this goal. Due to the explicit zero-point of signals, the live load-induced response has an inherent advantage for quantitatively representing the performance of bridges. Taking a long-span cable-stayed railway-highway combined bridge as the case study, this paper presents a representation method of in-service performance. First, the non-stationary sections of train-induced response are automatically extracted by wavelet transform and window with threshold. Then, the data of the feature parameter of each non-stationary section are automatically divided into four cases of train load according to the calculational theory of bridge vibration under train effect and clustering analysis. Finally, the performance indexes for structural deformation and dynamics are determined separately, based on hierarchical clustering and statistical modeling. Fusing the real variability of massive data from monitoring and the knowledge of mechanics of theoretical calculations, accurate and robust indexes of bridge deflection distribution and forced vibration frequency are obtained in real time. The whole process verifies the feasibility of the representation of bridge in-service performance from massive multisource sensing data. The presented method, framework, and analysis results can be used as a reference for the design, operation, and maintenance works of long-span railway bridges.
A subset of parasagittal and parafalcine (PSPF) meningiomas may show early progression/recurrence (P/R) after surgery. This study applied machine learning using combined clinical and texture features to predict P/R in PSPF meningiomas. A total of 57 consecutive patients with pathologically confirmed (WHO grade I) PSPF meningiomas treated in our institution between January 2007 to January 2019 were included. All included patients had complete preoperative magnetic resonance imaging (MRI) and more than one year MRI follow-up after surgery. Preoperative contrast-enhanced T1WI, T2WI, T1WI, and T2 fluid-attenuated inversion recovery (FLAIR) were analyzed retrospectively. The most significant 12 clinical features (extracted by LightGBM) and 73 texture features (extracted by SVM) were combined in random forest to predict P/R, and personalized radiomic scores were calculated. Thirteen patients (13/57, 22.8%) had P/R after surgery. The radiomic score was a high-risk factor for P/R with hazard ratio of 15.73 (p < 0.05) in multivariate hazards analysis. In receiver operating characteristic (ROC) analysis, an AUC of 0.91 with cut-off value of 0.269 was observed in radiomic scores for predicting P/R. Subtotal resection, low apparent diffusion coefficient (ADC) values, and high radiomic scores were associated with shorter progression-free survival (p < 0.05). Among different data input, machine learning using combined clinical and texture features showed the best predictive performance, with an accuracy of 91%, precision of 85%, and AUC of 0.88. Machine learning using combined clinical and texture features may have the potential to predict recurrence in PSPF meningiomas.
The normal feeling of touch is vital for nearly every aspect of our daily life. However, touching is not always felt as touch, but also abnormally as pain under numerous diseased conditions. For either mechanistic understanding of the faithful feeling of touch or clinical management of chronic pain, there is an essential need to thoroughly dissect the neuropathological changes that lead to painful touch or tactile allodynia and their corresponding cellular and molecular underpinnings. In recent years, we have seen remarkable progress in our understanding of the neural circuits for painful touch, with an increasing emphasis on the upstream roles of non-neuronal cells. As a highly specialized form of axon ensheathment by glial cells in jawed vertebrates, myelin sheaths not only mediate their outstanding neural functions via saltatory impulse propagation of temporal and spatial precision, but also support long-term neuronal/axonal integrity via metabolic and neurotrophic coupling. Therefore, myelinopathies have been implicated in diverse neuropsychiatric diseases, which are traditionally recognized as a result of the dysfunctions of neural circuits. However, whether myelinopathies can transform touch into pain remains a long-standing question. By summarizing and reframing the fragmentary but accumulating evidence so far, the present review indicates that sensory root demyelination represents a hitherto underappreciated neuropathological change for most neuropathic conditions of painful touch and offers an insightful window into faithful tactile sensation as well as a potential therapeutic target for intractable painful touch.
Demyelinating Diseases , Peripheral Nervous System Diseases , Animals , Hyperalgesia , Pain , Touch/physiology
