Crystal Length Research Articles

Enhanced lead adsorption by eco-hydroxyapatite derived from marble sludge: Optimization and kinetic study

In this study, eco-hydroxyapatite (e-HAP) was synthesized from marble sludge via a hydrothermal process for utilization as an adsorbent in the removal of Pb2+ ions from wastewater. X-ray powder diffraction (XRD) and thermal field emission scanning electron microscope (FE-SEM) revealed that increasing the Ca/P molar ratio (CPMR) and hydrothermal temperature (HT) increased crystallinity and that the influence of HT was more apparent. An increase in crystallinity, crystal length, and peak intensity was observed following an increase in the CPMR. Adsorption studies show that when the HT was 393 K, the CPMR was 0.67, the initial Pb2+ ion concentration was 100 mg/L, the equilibrium time was 20 min, and the adsorbent dosage was 0.6 g/L. The resulting removal efficiency (99.99 %) and maximum adsorption capacity (166.65 mg/g) are both very high. Adsorption kinetics are well described using a pseudo-second-order kinetic model. This paper presents a facile and economically sustainable approach to the synthesis of e-HAP from marble sludge for use in removing of Pb2+ from wastewater.

Performance studies on group-velocity-matched femtosecond optical parametric generation

We present a comparative study and detailed characterization of high-power femtosecond optical parametric generation (OPG) at 10 MHz repetition rate in the near and mid-infrared by exploiting near-zero group-velocity-mismatch (GVM) in the nonlinear crystals of PPLN and MgO:PPLN. Using a microchip-started amplified Mamyshev fiber oscillator delivering 198 fs pulses at 1064 nm as the pump source and deploying 19-mm-long PPLN and 42-mm-long MgO:PPLN as gain media, we study in detail the influence of crystal length and pump pulse duration on femtosecond group-velocity-matched interaction in the OPG process. The OPG source is tunable across 1445–1577 nm in the signal and 3318–4412 nm in the idler, and can provide average output powers of up to 439 mW in the signal at 1530 nm and 197 mW in the idler at 3550 nm, at slope efficiencies of ∼50% and ∼20%, respectively. Signal pulses as short as 275 fs are obtained using the shorter crystal, while longer signal pulses with similar output powers are generated with the longer crystal. Experimental results are supported by theoretical simulations, providing good agreement. The OPG source exhibits excellent power stability with high spatial quality of M2<1.5 in the signal and idler beams.

Praseodymium induced symmetry switching and electrochemical characteristics of LaCoO3 nanostructures

A comparative study of the crystal structures and electrochemical characteristics of bulk and nanoscale La1-xPrxCoO3 (x = 0, 0.3 and 0.6) perovskites is made using synchrotron x-ray diffraction, cyclic voltammetry, and galvanostatic charge/discharge methods. It is shown that the sol-gel synthesized nano structures and bulk LaCoO3 exhibit different crystal structures, viz., rhombohedral [a = b = 5.4401 Å, c = 13.134 Å (on hexagonal axes), Z = 6, R3‾c] and monoclinic [am = 5.3865 Å, bm = 5.4482 Å, cm = 7.6365 Å, βm = 89.010°, Z = 4, I2/a], respectively. The evidence for CoO6 octahedra distortion in bulk LaCoO3 is also gathered from the three distinct Raman active modes at 518, 646, and 688 cm−1 emerging due to the Jahn-Teller effect, which, in-turn, reduces the crystal symmetry for achieving structure stabilization. This amounts to changes in Co–O bond lengths and Co–O–Co bond angles with promotion of t2g electron to eg level simultaneously for Co3+(3d6) to attain an intermediate spin state (S = 1) or higher. However, Pr-insertion induces phase transition to orthorhombic in both but with space group Pnma in nanostructures and equivalent Pbnm in bulk. The substitution effect on the specific capacitance (C) is opposite in nature, i.e., while ‘C’ decreases from 149 to 12 F/g in nano structures, it increases from 0.4 to 4 F/g in bulk with increase in Pr-content from x=0 to 0.6. A galvanostatic charge-discharge test of pristine nano LaCoO3 performed at a constant scan rate of 50 mVs−1 reveals electrode electrochemical stability by retaining 96 % of specific capacitance ∼82.5 F/g for 2000 cycles at least. The variation in the crystal structure and bond length and/or angle plays a key role in controlling the electrochemical performance of Pr-substituted LaCoO3 perovskites.

Preparation of aragonite-rich whisker materials from magnesium slag and salt lake bischofite and its effects on cement properties

This study develops an innovative wet carbonation process utilizing Magnesium Slag(MS), Salt Lake Bischofite (SLB), and CO2 to prepare carbonized materials mainly composed of aragonite and active silica gel, all raw materials were solid wastes. Subsequently, it was employed as Supplementary Cementitious Materials (SCMs) additive in cement, with the goal of efficiently capturing carbon dioxide and transforming aragonite whiskers into high-value products. Investigated the parameters influencing the formation of aragonite, including temperature and the concentration of the SLB solution, while exploring the nucleation and growth mechanisms of aragonite. The findings reveal that under 80 °C, the suspension of MS with 0.83 % SLB solution swiftly produces needle-like aragonite whiskers with single crystal lengths ranging from 10-20 μm and diameters of 0.3–0.5 μm. With the increase in SLB concentration, the aspect ratio of aragonite whiskers decreases. Additionally, highly polymerized amorphous silica gel was also detected. Therefore, Carbonated Aragonite-type Magnesium Slag (CAMS) (34.0901 m2/g) exhibits a significantly larger specific surface area compared to MS (0.9877 m2/g), representing an enhancement factor of 34.5 times, which concurrently bolsters its capability to adsorb reactive ions. During the carbonation process, 1 g of MS can sequester and solidify 0.403 g of CO2. Furthermore, incorporating CAMS as SCMs into cement mixtures notably enhances both the compressive and flexural strengths of cement mortar. These findings offer a sustainable approach to the recycling of solid waste, CO2 sequestration, and the improvement of cement-based material properties.

Quantum ghost imaging microscopy depth-of-field study

Quantum ghost imaging approaches have been proposed to enhance biological microscopy, for example, using 2D visible detectors to provide IR images or providing additional dimensions of spatial or spectral information. Toward the goal of making such imaging schemes practical, we compare image quality and depth-of-field between traditional images and ghost images at the same excitation levels. We measure how image quality and depth-of-field depend on the parameters of the entangled light produced using type-I spontaneous parametric down-conversion (SPDC). We use a pair of time-synchronized, photon-timing single-photon avalanche diode (SPAD) array detectors to capture two distinct microscope imaging paths simultaneously on a photon-pair-by-photon-pair basis: one in a traditional imaging pathway and the other a quantum ghost imaging pathway. We calculate the depth-of-field, resolution, contrast, and signal-to-noise ratio (SNR) through the parameter space of a β-Barium Borate (BBO) type-I bulk non-linear crystal length and angle. Our results provide a basis for choosing parameters for quantum ghost imaging with type-I SPDC sources.

Development of biochromic paper strips from cellulose nanocrystals and anthocyanin extract from pomegranate (Punica granatum L.) for colorimetric determination of urea

AbstractAn anthocyanin (ACN) spectroscopic probe was extracted and immobilized into a matrix of cellulose nanocrystals (CNC)/urease enzyme to create a colorimetric nanocomposite film sensor. The ACN@CNC composite is a disposable molecular biosensor that uses urease as a catalyst, ACN as a molecular probe, and CNC as a probe carrier with a high surface area. The ACN spectroscopic probe was isolated from the pomegranate peel (Punica granatum L.). A mordant was applied to fix ACN onto CNC by forming nanoparticles (6–14 nm) of mordant/ACN (M/ACN) complexation. CNC showed diameters in the range of 11–21 nm, and crystal lengths of 55–130 nm. Under acid/base conditions, the ACN probe solution in distilled water exhibited a reversible color change, as shown by the UV–Vis absorption spectra. In order to create a biocomposite film, CNC were reinforced with a sodium alginate biopolymer. Upon exposure to urea in an aqueous solution, the ACN@CNC film biosensor changes color from purple (598 nm) to white (432 nm). The detection limit of urea was determined at 25–450 ppm. Various methods were utilized to investigate the morphological properties of CNC and ACN@CNC films.

A novel simplified method for assessing crystal length and crystalline content in dental ceramics.

The purpose of this study was to introduce a novel and simple method of evaluating the crystal length and crystalline content of lithium disilicate dental ceramics using images obtained from scanning electron microscopy (SEM) and analyzed with ImageJ (NIH) processing software. Three evaluators with varying experience levels assessed the average crystal length and percentage of crystalline content in four commercial lithium disilicate reinforced glass ceramic materials: IPS e.max (Ivoclar Vivadent), Rosetta SM (Hass), T-Lithium (Talmax), and IRIS CAD (Tianjin). The specimens, prepared from partially crystallized CAD/CAM blocks (3.0 mm3), were fully crystallized and treated with 5% hydrofluoric acid for 20 s prior to SEM analysis. After acquiring the SEM images, ImageJ software was used to evaluate the average crystal length and crystalline content on the surface of the different ceramics. An inter-operator agreement was observed (ICC/p = 0.724), indicating that assessments by the various operators were similar across all ceramic materials tested (p < 0.001). When crystal length and crystalline content were compared, IRIS CAD exhibited significant differences compared to the other materials (p < 0.001), showing a less dense crystalline matrix based on the average length of crystals and the percentage of crystals per unit area. The use of this software facilitated the evaluation of crystalline content and average crystal lengths in dental ceramics using SEM images, and demonstrated very low variability among different operators. RESEARCH HIGHLIGHTS: The described method, using ImageJ open-source software, provides precise and reliable measurements of crystal length and crystalline content in lithium disilicate ceramics, with high inter-operator agreement. The proposed method identifiedhigher crystalline content in IPS e.max CAD compared to Rosetta SM CAD and T-lithium CAD ceramics, while IRIS CAD exhibited significantly lower crystalline content and larger average crystal length. The novel, simplified method for assessing crystal length and crystalline content presented in this study may also be useful for evaluating other dental ceramics.

A quantitative analysis on the effect of crystal parameters on full energy peak efficiency of a coaxial high purity Germanium detector for the energy range 50 keV-2.5 MeV

High Purity Germanium (HPGe) detectors are essential instruments in gamma-ray spectrometry, offering high sensitivity and exceptional energy resolution. The full-energy-peak (FEP) efficiency is a critical parameter that influences the accuracy of activity concentration measurements of radionuclides. This study examines the FEP efficiency of a coaxial HPGe detector, focusing on variations in crystal length, crystal radius, and crystal hole dimensions. For varying crystal lengths, the efficiency values show negligible differences at low energy (50 keV) but significant increases at higher energies, indicating that longer crystal lengths enhance efficiency. Similarly, the efficiency increases with larger crystal radii across all energy levels suggesting substantial efficiency gains even at low energies. However, variations in crystal hole radius and depth, exhibit minimal impact on FEP efficiency across all tested energy levels. These findings highlight that optimizing crystal length and radius is more crucial for changing detector efficiency compared to modifying hole dimensions, providing valuable insights for optimizing Monte Carlo models and detector design.

Simple non-fused ring electron acceptors enables effective organic solar cells by employing heptan-3-yloxyl side chains

Designing low-cost electron acceptors for effective bulk heterojunction (BHJ) organic solar cells (OSCs) is challenging. Here, we report two low-cost electron acceptors (TT-BO and TT-EH) with the same core of heptan-3-yloxylated thieno[3,2-b]thiophene, differing only in the alkylated thiophene-bridges. Both acceptors have similar low optical gaps (≈1.40 eV), but TT-EH exhibits a more ordered microstructure in thin film and higher electron mobility of 2.0 × 10−4 cm2 V−1 s−1 compared to TT-BO (1.7 × 10−4 cm2 V−1 s−1). After blending with the polymer donor, the TT-EH blend film shows a longer crystal coherence length of 2.4 nm for π-π stacking. Consequently, the TT-BO-based OSC achieves a 13.1 % power conversion efficiency (PCE). In contrast, the TT-EH-based OSC produces an excellent PCE of 14.2 %, the highest value among this kind of electron acceptors. This work offers a new insight into designing low-cost electron acceptors for efficient OSC.

Study on the Binding Behavior of Chloride Ion and Ettringite in Nano-Metakaolin Cement by Seawater Mixing and Curing Temperatures.

Mixing cement with seawater will cause the hydration process of cement to be different from that of ordinary cement, which will significantly affect cement's mechanical properties and durability. This article investigates the effects of chloride ion concentration, curing temperature, and nano-metakaolin content on the evolution process of Friedel's salts and ettringite (AFt) crystals in cement pastes. The study was conducted using X-ray diffraction (XRD), thermal analysis (TG), scanning electron microscopy (SEM), and mercury-intrusion porosimetry (MIP). The results show that chlorine salt can increase the production of Friedel's salt and ettringite, and the delayed AFt production increases by up to 27.95% after the addition of chlorine salt, which has an adverse effect on cement-based materials. Increasing the curing temperature and increasing the nano-metakaolin dosage increased the generation of Friedel's salt and decreased the delayed AFt generation, which resulted in a decrease in the length and diameter of the AFt crystals. After 28 days of high-temperature curing and the addition of nano-metakaolin, Friedel's salt production increased by 13.40% and 14.34%, respectively, and ettringite production decreased by 9.68% and 7.93%, respectively. Increasing the curing temperature and adding nano-metakaolin can reduce the adverse effect of delayed ettringite increases due to chloride ion binding.

The dielectric response of a novel low-loss oxyfluoride Li0.5NaY9(SiO4)6O2F0.5 ceramic from Gigahertz band to Terahertz band

The exploration of dielectric ceramics with excellent dielectric responses at Gigahertz band and Terahertz band is becoming urgent for the upcoming 6th generation wireless communication. In this work, we propose a new approach to design novel dielectric ceramics by using the density functional theory. According to the analysis of Electron Localization Functions (ELF), Density of States (DOS) and crystal bond lengths, it indicates that the strategy of co-doping with lithium and fluorine will contribute to a much more stable crystal structure of Li0.5NaY9(SiO4)6O2F0.5 as compared to that of NaY9(SiO4)6O2. Furthermore, we report the innovative synthesis of a Li0.5NaY9(SiO4)6O2F0.5 oxyfluoride ceramic, a solid solution with a wide sintering temperature range, along with an in-depth analysis of its crystal structure, dielectric responses at both Gigahertz band and Terahertz band, which shows the promising application of Li0.5NaY9(SiO4)6O2F0.5 in the 6G wireless communication.

Optimization of Pump Pulse Duration and Cr:ZnSe Crystal Length for Efficient Generation of Tunable Mid-IR Laser Radiation Pumped by Laser Diode at Room Temperature

Optimization of Pump Pulse Duration and Cr:ZnSe Crystal Length for Efficient Generation of Tunable Mid-IR Laser Radiation Pumped by Laser Diode at Room Temperature

Modelling of long-wave mid-infrared ultrashort pulse generation via difference frequency generation

In this paper, a model of generating mid-infrared (MIR) ultrashort laser pulse through difference frequency generation (DFG) is established. The pulse evolution relationship among the pump, signal, and idler pulses during the DFG process, as well as the effects of crystal length, pulse energy of the pump and signal lights, pulse width, and other factors on the characteristics of the MIR pulse are explored. Furthermore, through simulations from the time domain to the frequency domain, the spectral characteristics and angular distribution of MIR were analyzed. DFG experimental data are also presented to support the model.

Water-Soluble Lead Sulfide Nanoparticles: Direct Synthesis and Ligand Exchange Routes.

Colloidal semiconductor nanoparticles (NPs) represent an emergent state of matter with unique properties, bridging bulk materials and molecular structures. Their distinct physical attributes, such as bandgap and photoluminescence, are intricately tied to their size and morphology. Ligand passivation plays a crucial role in shaping NPs and determining their physical properties. Ligand exchange (LE) offers a versatile approach to tailoring NP properties, often guided by Pearson's Hard-Soft Acid-Base theory. Lead sulfide (PbS), a semiconductor of considerable interest, exhibits size-dependent tunable bandgaps from the infrared to the visible range. Here, we present two methods for synthesizing water-soluble, polyvinylpyrrolidone (PVP)-coated PbS NPs. The first involves direct synthesis in an aqueous solution while utilizing PVP as the surfactant for the formation of nano-cubes with a crystal coherence length of ~30 nm, while the second involves LE from octadecylamine-coated PbS truncated nano-cubes to PVP-coated PbS NPs with a crystal coherence length of ~15 nm. Multiple characterization techniques, including X-ray diffraction, transmission electron microscopy, Fourier-transform infrared spectroscopy, and thermal gravimetric analysis, confirmed the results of the synthesis and allowed us to monitor the ligand exchange process. Our findings demonstrate efficient and environmentally friendly approaches for synthesizing PVP-coated PbS NPs.

The Crystallization of Continental Flood Basalt Lavas: Insights from Textural Studies

Abstract Continental flood basalt (CFB) provinces are products of the largest known volumetric eruptions on Earth (~104 km3), with individual flow fields commonly covering well over 10 000 km2 with a mean lava thickness of over 5 m. Studies focusing on the emplacement style of such lava flows have relied extensively on morphological observations and comparisons with modern lava flows and experimental analogs. In the present study, we compare the textures of flood basalt lavas with those from different eruption settings all over the world using data collected from pre-existing literature to gain detailed insights into the style of eruption. Comparison of crystal size distribution data indicates that the eruption style of CFBs is similar to those of modern-day fissure eruptions (e.g. Iceland). This matches inferences based on observations of morphology. We also use a 1D thermal model to estimate the depth-dependent cooling rates within a single lava lobe and test the validity of assumptions built into the formulation of these models for large scale flood basalt lavas. The results reveal that, on average, flood basalt lavas need to conductively cool much faster than we would expect (up to order of ~102 times faster) to match the textural observations. The model is also frequently unable to replicate the observed depth-wise relative variations in length with depth for CFB lavas. Furthermore, the calculated cooling rates from crystal shapes also do not match those calculated from crystal lengths, indicating the assumptions in cooling flow models need to be modified for large CFB flow fields. Given the large areas of CFB flow fields and the relatively long eruption times inferred for the emplacement of individual flow fields, we hypothesize that inflation of lobes and formation of new lobes via breakouts combined with variable eruption rates are key processes that are missing when modeling the cooling of these flow fields. Accounting for these processes is essential to derive accurate cooling rates, which is important to better understand the environmental impact CFBs have at the time of emplacement.

Non-contact ultrasonic vibration-assisted laser metal deposition manufacturing Fe-based powder: Numerical simulation and experimental investigation

Fe-based powder was manufactured on 42CrMoA steel substrate using non-contact ultrasonic vibration-assisted(UVA) laser metal deposition(LMD) process with different exciting distances(d), and the temperature field and stress field distribution, microstructure and mechanical properties of the deposited layers were investigated. The results show that the distribution of temperature field was more uniform, especially at the bottom of the molten pool, and the gradient of temperature field decreased. Compared with the condition without UVA, the residual stress peak value of the tensile stress area decreased significantly after UVA applied. When d=80 mm, the peak tensile stress and compressive stress were 90.5 MPa and 72.6 MPa, respectively, which were reduced by 45.6 % and 25.2 % compared with the condition without UVA. The length of the columnar crystals and the region of the columnar crystals decreased at the interface after UVA applied. The application of UVA can significantly improved the microhardness of deposition layer. With the reduction of the residual stress at the interface and the improvement of uniformity, the tensile properties of the deposit were also significantly improved. The highest tensile strength was 1281.3 MPa when d=80 mm, which was 30.12 % higher than that without UVA.

Few-mode squeezing in type-I parametric downconversion by complete group velocity matching.

Frequency-degenerate pulsed type-I parametric downconversion is a widely used source of squeezed light for numerous quantum optical applications. However, this source is typically spectrally multimode, and the generated squeezing is distributed between many spectral modes with a limited degree of squeezing per mode. We show that in a nonlinear crystal, where the condition of complete group velocity matching (GVM) for the pump and the signal is satisfied, the number of generated modes may be as low as two or three modes. We illustrate the general theory with the example of the MgO-doped lithium niobate crystal pumped at 775 nm and generating squeezed light at 1.55 µm. Our model includes the derivation of the degree of squeezing from the properties of the pump and the crystal and shows that 12 dB of squeezing can be obtained in a periodically poled crystal ata length of 80 mm.

Characterization of Crystals in Ciliate Paramecium bursaria Harboring Endosymbiotic Chlorella variabilis

Protists, including ciliates retain crystals in their cytoplasm. However, their functions and properties remain unclear. To comparatively analyze the crystals of Paramecium bursaria, a ciliate, associated with and without the endosymbiotic Chlorella variabilis, we investigated the isolated crystals using a light microscope and analyzed their length and solubility. A negligible number of crystals was found in P. bursaria cells harboring symbiotic algae. The average crystal length in alga-free and algae-reduced cells was about 6.8 μm and 14.4 μm, respectively. The crystals of alga-free cells were spherical, whereas those of algae-reduced cells were angular in shape. The crystals of alga-free cells immediately dissolved in acids and bases, but not in water or organic solvents, and were stable at – 20 °C for more than 3 weeks. This study, for the first time, reveals that the characteristics of crystals present in the cytoplasm of P. bursaria vary greatly depending on the amount of symbiotic algae.

Estimation of soot refractive index from its nanostructural parameters with the dispersion model

Particles derived from combustion processes, mainly composed of soot agglomerates, are acknowledged to be among the main contributors to climate change. Their effects depend mostly on their size, shape, and internal structure. Specifically, the latter has a significant effect on their optical properties, mainly through the refractive index. This index has been widely evaluated, but scarcely correlated with the soot internal characteristics. In this work, relationships between the nanostructural parameters (such as the degree of graphitization, among others) obtained with conventional analytical techniques and the input parameters of the dispersion model (a representation of the electromagnetic radiation through the Lorentz-Drude approach) are proposed with the aim to determine the refractive index. From experiments in a chassis dynamometer, it has been observed that as the vehicle speed increases, the soot samples have, in general, higher degree of graphitization, due to increased combustion temperature. The method proposed allows quantifying how both the real and imaginary parts of the complex refractive index increase as the degree of graphitization increases. Much lower dependence on the average crystal length has been observed. Different combinations of techniques can be used to determine the nanostructural parameters, depending on the analytical technique used. As far as the resulting parameters are reliable, the effect of the technique selected is minor, thus providing flexibility to the application of the method.

Cherenkov second harmonic generation of femtosecond laser pulses in a homogeneous nonlinear crystal

In experiments on second harmonic (SH) generation (SHG), a conical structure of radiation has been observed. In the present study, a non-stationary theory of SH excitation of ultrashort laser pulses with phase modulation has been developed, which explains the properties of such a structure as Cherenkov radiation. Under phase-mismatched interactions, a maximum of the SH spectrum is observed at the Cherenkov angle, which is determined by the ratio of the SH and laser radiation phase velocities. It is shown that tightly focused laser beams are preferred to observe Cherenkov SHG. The SH spectral width depends on the group velocity mismatch and is more complicated on the excited radiation spectrum. The SH energy can be proportional to the crystal length or group delay length depending on their ratio. We also demonstrate that a complex angular distribution of spectral components (an angular chirp) appears within the SH cross-section.