Greenhouse gas reduction and nitrogen conservation during manure composting by combining biochar with wood vinegar.

The constant greenhouse gases (GHGs) and ammonia emissions during pig manure (PM) composting have made large contributions to air pollution and global temperature rise. This study aimed to evaluate the addition of biochar (B) and wood vinegar (WV) to reduce GHGs emissions and improve nitrogen retention and microbial activities during PM composting. Different treatments, carried out under a 1:2 ratio (dry weight) of PM and sawdust mixture with the addition of B (5%) and various proportions of WV, include a control treatment (CT) without the addition of B and WV and, B, B+0.5%WV, B+1.0%WV, B+1.5%WV, and B+2.0%WV treatments. The results indicated that the addition of B could accelerate the composting process in contrast to CT. In addition, various amounts of WV with B decreased NH3, CO2, CH4 and N2O emissions by 18.82-35.88%, 1.38-15.39%, 16.98-62.73%, and 4.47-19.91%, respectively. Furthermore, in contrast to the B treatment, WV addition was more effective in decreasing GHGs and NH3 emissions, and the B+1.0% WV treatment displayed the lowest nitrogen loss (2.12%) and GHGs emissions (11.62 g/kg). The bacterial community analysis demonstrated that synergistic application of WV and B can increase the relative abundance of Proteobacteria which can contribute to nitrogen fixation and reduction of nitrogen loss. The results proved that combining B with WV can be a feasible strategy to effectively reduce GHGs emissions and improve nitrogen conservation in the composting industry.

Direct Evidence for an Intermediate Multiferroic Phase in LiCuFe2(VO4)3.

Magnetic susceptibility, specific heat, dielectric, and electric polarization of LiCuFe2(VO4)3 have been investigated. Two sequential antiferromagnetic transitions at TN1 ∼ 9.95 K and TN2 ∼ 8.17 K are observed under zero magnetic field. Although a dielectric peak at TN1 is clearly identified, the measured pyroelectric current also exhibits a sharp peak at TN1, implying the magnetically relevant ferroelectricity. Interestingly, another pyroelectric peak around TN2 with an opposite signal is observed, resulting in the disappearance of electric polarization below TN2. Besides, the electric polarization is significantly suppressed in response to external magnetic field, evidencing a remarkable magnetoelectric effect. These results suggest the essential relevance of the magnetic structure with the ferroelectricity in LiCuFe2(VO4)3, deserving further investigation of the underlying mechanism.

Magnetoelectric Effect in Garnet Mn3Al2Ge3O12.

Searching for novel magnetoelectric (ME) materials has been one of the major issues of multiferroics. In this work, we present a systematic research study on garnet Mn3Al2Ge3O12, including structural, magnetic, heat capacity, and ME characterizations. Below the Néel temperature TN ∼ 6.8 K, Mn2+ spins form a long-range antiferromagnetic order, and a magnetic field H-driven electric polarization P is identified simultaneously. The relationship between P and H is nonlinear under low H and becomes linear under high H. Such transition is believed to originate from the H-induced variation of the magnetic structure. In addition, the P reaches 0.6 µC/m2 under µ0H = 9 T, corresponding to an ME coupling coefficient of αME ∼ 0.08 ps/m under high H. The small αME is attributed to the weak spin-orbit coupling and weak magnetic interactions in Mn3Al2Ge3O12. Furthermore, we realize the stable control of P by periodically varying H, which is crucial for potential application. We provide a rare case that a garnet material shows a first-order ME effect.

Antiferromagnetism of Double Molybdate LiFe(MoO4)2.

The magnetic properties of the spin-5/2 double molybdate LiFe(MoO4)2 have been characterized by heat capacity, magnetic susceptibility, and neutron powder diffraction techniques. Unlike the multiferroic system LiFe(WO4)2 which exhibits two successive magnetic transitions, LiFe(MoO4)2 undergoes only one antiferromagnetic transition at TN ∼ 23.8 K. Its antiferromagnetic magnetic structure with the commensurate propagation vector k = (0, 0.5, 0) has been determined. Density functional theory calculations confirm the antiferromagnetic ground state and provide a numerical estimate of the relevant exchange coupling constants.

Electro-opto-mechano driven reversible multi-state memory devices based on photocurrent in Bi0.9Eu0.1FeO3/La0.67Sr0.33MnO3/PMN-PT heterostructures.

A single device with extensive new functionality is highly attractive for the increasing demands for complex and multifunctional optoelectronics. Multi-field coupling has been drawing considerable attention because it leads to materials that can be simultaneously operated under several external stimuli (e.g. magnetic field, electric field, electric current, light, strain, etc.), which allows each unit to store multiple bits of information and thus enhance the memory density. In this work, we report an electro-opto-mechano-driven reversible multi-state memory device based on photocurrent in Bi0.9Eu0.1FeO3 (BEFO)/La0.67Sr0.33MnO3 (LSMO)/0.7Pb(Mg1/3Nb2/3)O3-0.3PbTiO3 (PMN-PT) heterostructures. It is found that the short-circuit current density (J sc) can be switched by the variation of the potential barrier height and depletion region width at the Pt/BEFO interface modulated by light illumination, external strain, and ferroelectric polarization reversal. This work opens up pathways toward the emergence of novel device design features with dynamic control for developing high-performance electric-optical-mechanism integrated devices based on the BiFeO3-based heterostructures.

Clanis bilineata larvae skin-derived biochars for immobilization of lead: Sorption isotherm and molecular mechanism.

Clanis bilineata larva skin (CBLS), a new residue from the food industry, was first used to produce biochars by pyrolysis at 300 °C (CBLS300) and 700 °C (CBLS700), respectively, for Pb immobilization. The sorption isotherms and immobilization mechanisms of Pb on two biochars were investigated. CBLS700 exhibited more high-efficiency in sorption of Pb than CBLS300 due to the predicted maximum sorption capacity of CBLS700 (77.52 mg/g) was larger than that of CBLS300 (49.02 mg/g). Synchrotron-based microfocused X-ray fluorescence analysis exhibited the co-distribution of Pb and P in the sorption product of CBLS700 rather than CBLS300. Microfocused X-ray absorption near-edge structure analysis highlighted the significance of organic ligand in the biochar for Pb immobilization due to both sorption products have organic complexed Pb. Moreover, 25% of total Pb was present as hydrocerussite on CBLS300 but partially transformed into stable hydroxylpyromorphite on CBLS700 (~21%), which was in accordance with the analysis of scanning electron microscopy coupled with energy disperse spectra. Additionally, addition of CBLS700 was more effective in reducing the leachable Pb in shooting range soil than that of CBLS300. These results strongly suggested the potential application of the new biochar (CBLS700) for the remediation of Pb-contaminated soils.

Step-by-Step Assembly of Metal-Organic Frameworks from Trinuclear Cu3 Clusters.

Two novel metal-organic frameworks (MOFs), HBNU-1 and HBNU-2, have been synthesized successfully. We adopt a step-by-step assembly strategy, which first synthesize the Cu3 cluster Cu3(µ3-OH)(pz)3(CH3COO)2(Hpz), and then react it with H2BDC under different conditions to form final frameworks. In both MOF structures, the Cu3 clusters are maintained, although certain differences are observed. Compared with HBNU-1, the Cu3 cluster dimerizes into Cu6 cluster in HBNU-2. With this step-by-step cluster assembly strategy, MOF structure predicting becomes possible and may give some reference for MOF structure designing.

Pd Nanoparticle Film on a Polymer Substrate for Transparent and Flexible Hydrogen Sensors.

Alongside the rise in fully automated equipment and wearable devices, there is currently a high demand for optically transparent and flexible gas sensors operating at room temperature. Nanoparticle films are ideal H2-sensing materials that can be coupled with flexible substrates because of their discrete nanogranular structure and unique interparticle electrical responsiveness. In this work, we present an optically transparent and flexible H2 sensor based on a Pd nanoparticle film, prepared on a polyethylene terephthalate sheet using a straightforward nanocluster deposition technique. Hundreds of bending cycles demonstrated that the sensor has good electrical stability and mechanical robustness without significant degradation in H2-sensing performance. The H2-sensing behaviors under bent state were systematically evaluated. The loading of tensile and compressive strains under bent state produced a positive and negative influence, respectively, on the sensing performances. The possible influence mechanism of the tensile and compressive strains on the H2-sensing performance was attributed to the changes in the percolation network topology and the interparticle space induced by the strains. The ability to detect a H2 concentration as low as 15 ppm, dynamic response range as wide as 0-10%, and sub-10 s response time was achieved. In addition, the sensor can be operated in the relative humidity range of 0-90% at room temperature. These results demonstrate that the sensor exhibits significant potential for next-generation transparent and flexible H2 detectors.

Organic amines as templates: pore imprints with exactly matching sizes in a series of metal-organic frameworks.

Three kinds of organic amines have been used as soft templates for constructing a series of metal-organic frameworks with variable pores. The pore sizes of these MOFs exactly matched those of amines, confirming the template effect of these amines.

Response Characteristics of Hydrogen Sensors Based on PMMA-Membrane-Coated Palladium Nanoparticle Films.

Coating a polymeric membrane for gas separation is a feasible approach to fabricate gas sensors with selectivity. In this study, poly(methyl methacrylate)-(PMMA-)membrane-coated palladium (Pd) nanoparticle (NP) films were fabricated for high-performance hydrogen (H2) gas sensing by carrying out gas-phase cluster deposition and PMMA spin coating. No changes were induced by the PMMA spin coating in the electrical transport and H2-sensing mechanisms of the Pd NP films. Measurements of H2 sensing demonstrated that the devices were capable of detecting H2 gas within the concentration range 0-10% at room temperature and showed high selectivity to H2 due to the filtration effect of the PMMA membrane layer. Despite the presence of the PMMA matrix, the lower detection limit of the sensor is less than 50 ppm. A series of PMMA membrane layers with different thicknesses were spin coated onto the surface of Pd NP films for the selective filtration of H2. It was found that the device sensing kinetics were strongly affected by the thickness of the PMMA layer, with the devices with thicker PMMA membrane layers showing a slower response to H2 gas. Three mechanisms slowing down the sensing kinetics of the devices were demonstrated to be present: diffusion of H2 gas in the PMMA matrix, nucleation and growth of the ß phase in the α phase matrix of Pd hydride, and stress relaxation at the interface between Pd NPs and the PMMA matrix. The retardation effect caused by these three mechanisms on the sensing kinetics relied on the phase region of Pd hydride during the sensing reaction. Two simple strategies, minimizing the thickness of the PMMA membrane layer and reducing the size of the Pd NPs, were proposed to compensate for retardation of the sensing response.