Canopy litter is an important component of coarse woody debris (CWD), which affects nutrient and carbon cycling in forest ecosystems. For marcescent plant species (characterized by dead branches and ...leaves remaining in the canopy for several years before abscission), nutrient resorption from senescing leaves is an important nutrient conservation strategy. However, investigating the ecological function of canopy litter is challenging due to its limited accessibility and also the heterogeneous canopy microclimate in terms of light transmission, temperature and moisture. We studied the spatiotemporal distribution of canopy litter mass and seasonal dynamics of leaf nutrients and nutrient resorption during senescence in the canopy along a chronosequence of Chinese fir Cunninghamia lanceolata (Lamb.) Hook plantations in southeast China. The dry mass weight of dead branches and dead leaves in the canopy significantly increased with stand stage (14.6, 14.2, and 17.4 t ha−1 for young, middle-aged, and mature stands respectively), accounting for high proportions of total aboveground litter of 85.7%, 79.1% and 80.0%, respectively, along with annual litterfall production (2.44, 3.75, and 4.34 t ha−1, respectively). The canopy height distribution of dead branches and leaves also increased with stand age, ranging from 0 to 4 m in young stands, 3–8 m in middle-aged stands, to 4–10 m in mature stands. The seasonal pattern of canopy litter mass was the inverse of litterfall production: canopy litter mass peaked, while litterfall production was lowest in winter. Mean N, P, K, and Mg nutrient resorption efficiencies across stands at each stage were 53.8–58.9%, 64.0–68.9%, 85.0–90.2%, and 46.5–56.6%, respectively, while Ca was not retranslocated from senescing leaves. In summary, Chinese fir plantations retain large amounts of dead branches and leaves in the canopy from which at least ~50% of the nutrients N, P, K and Mg are recycled, representing an important nutrient conservation strategy that has evolved to adapt to nutrient-limited habitats. Canopy litter therefore plays an important role in these forest plantation ecosystems and should be protected instead of being removed from the canopy to the forest floor.
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•Canopy litter mass spatiotemporal dynamics varied in a Chinese fir chronosequence.•Canopy litter biomass increased over time, accounting for ~80% aboveground litter.•N, P, K, and Mg concentrations decreased during senescence before litterfall.•N, P, K, and Mg resorption efficiencies varied seasonally and among developmental stages.•Resorption from canopy litter contributes significantly to nutrient cycling.
Aluminum sulfate was employed as the main accelerator in order to explore new non-chloride and alkali-free cement accelerators. Acrylic acid, aluminum fluoride, or alkanolamine were used as ...regulators to further accelerate cement setting. The setting time, compressive, and flexural strengths in cement early strength progress were detected, and both the cement (raw material) and hydrated mortar were fully characterized. The cement setting experiments revealed that only loading acrylic acid as the regulator would decrease the setting time of cement and increase the compressive and flexural strengths of mortar, but further introduction of aluminum fluoride or alkanolamine improved this process drastically. In the meantime, structural characterizations indicated that the raw material (cement) used in this work was composed of C
S (alite), while hydrated mortar consisted of quartz and C
A (tricalcium aluminate). During this transformation, the coordination polyhedron of Al
was changed from a tetrahedron to octahedron. This work puts forward a significant strategy for promoting the activity of aluminum sulfate in cement setting and would contribute to the future design of new non-chloride and alkali-free cement accelerators.
The amounts of litter produced and nutrients returned play a fundamental role in the productivity and biogeochemical and nutrient cycling of forest ecosystems. We monitored annual litterfall ...production, nutrient return, and monthly dynamics over a one-year period in Chinese fir plantations aged 10, 22, and 34 years. Our objective was to quantify litterfall and nutrient return over a complete harvest rotation of Chinese fir. Annual litterfall production increased with stand age and was recorded as (3,294.6 ± 360.4), (3,733.9 ± 211.2), and (4,876.1 ± 212.8) kg ha⁻¹a⁻¹in stands aged 10, 22 and 34 years, respectively. Total litter production was significantly greater in the stand aged 34 years than in the stand aged 10 years (p < 0.05). With the exception of miscellaneous components, needle litterfall constituted the highest proportion (27.5–43.6 %), followed by branches/twigs (9.5–16.6 %). In all three plantations, annual total nutrient return to soil was in the order of C (1,119.95–2,709.05 kg ha⁻¹ a⁻¹) > N (39.32–62.04 kg ha⁻¹ a⁻¹) > K (15.95–22.44 kg ha⁻¹ a⁻¹) > P (1.30–1.63 kg ha⁻¹a⁻¹). C, N, K and P input to soil was significantly lower in the 10-year-old stand in comparison to the 22- and 34-year-old stands (p < 0.05). Litterfall production and nutrient return (C, N and K) followed similar patterns, and C and N input to soil was significantly related to litterfall production (needle, branch and total litterfall). C, N, P and K input to soil and total litterfall production were mainly driven by needle litterfall.
The amounts of litter produced and nutrients returned play a fundamental role in the productivity and biogeochemical and nutrient cycling of forest ecosystems.We monitored annual litterfall ...production, nutrient return,and monthly dynamics over a one-year period in Chinese fir plantations aged 10, 22, and 34 years. Our objective was to quantify litterfall and nutrient return over a complete harvest rotation of Chinese fir. Annual litterfall production increased with stand age and was recorded as（3,294.6 ± 360.4）,（3,733.9 ± 211.2）, and（4,876.1 ± 212.8） kg ha-1a-1in stands aged 10, 22 and 34 years, respectively. Total litter production was significantly greater in the stand aged34 years than in the stand aged 10 years（p ／ 0.05）. With the exception of miscellaneous components, needle litterfall constituted the highest proportion（27.5–43.6 %）, followed by branches/twigs（9.5–16.6 %）. In all three plantations,annual total nutrient return to soil was in the order of C（1,119.95–2,709.05 kg ha-1a-1） N（39.32–62.04 kg ha-1a-1） K（15.95–22.44 kg ha-1a-1） P（1.30–1.63 kg ha-1a-1）. C, N, K and P input to soil was significantly lower in the 10-year-old stand in comparison to the 22- and34-year-old stands（p ／ 0.05）. Litterfall production and nutrient return（C, N and K） followed similar patterns, and C and N input to soil was significantly related to litterfall production（needle, branch and total litterfall）. C, N, P and K input to soil and total litterfall production were mainly driven by needle litterfall.
Development of fast and sensitive sensors for glucose determination is important in food industry, clinic diagnostics, biotechnology and many other areas. In these years, considerable attention has ...been paid to develop non-enzymatic electrodes to solve the disadvantages of the enzyme-modified electrodes, such as instability, high cost, complicated immobilization procedure and critical operating situation et al. Nano nickel oxide (NiO) modified non-enzymatic glucose sensors with enhanced sensitivity were investigated. Potential scanning nano NiO modified carbon paste electrodes up to high potential in alkaline solution greatly increases the amount of redox couple Ni(OH)2/NiOOH derived from NiO, and thus improves their electrochemical properties and electrocatalytical performance toward the oxidation of glucose. The non-enzymatic sensors response quickly to glucose and the response time is less than 5s, demonstrating excellent electrocatalytical activity and assay performance. The calibration plot is linear over the wide concentration range of 1–110μM with a sensitivity of 43.9nA/μM and a correlation coefficient of 0.998. The detection limit of the electrode was found to be 0.16μM at a signal-to-noise ratio of 3. The proposed non-enzymatic sensors can be used for the assay of glucose in real sample.
Clenbuterol (CLB), a kind of β2-adrenergic agonists, could disrupt cardiovascular and central nervous system. In this work, a new electrochemical non-enzyme sensor for detecting Clenbuterol (CLB) was ...fabricated based on MoS2-Au-PEI-hemin layered nanocomposites. The two-dimensional (2-D) MoS2 nanosheets were first in-situ assembled with Au nanoparticles, and polyethylenimine (PEI), then hemin molecules were immobilized onto the MoS2-Au-PEI film-modified glassy carbon electrode (GCE) via amide bond. Scanning electron microscopy (SEM) and Zeta potential measurements were employed to characterize the MoS2-based nanomaterials. Cyclic voltammetry (CV) was used to investigate electrochemical activity of the immobilized hemin on the modified electrode. Upon the optimum conditions, the proposed electrochemical sensor showed an excellent response for CLB including a wide linear ranging from 10ng/mL to 2μg/mL and a detection limit (LOD) of 1.92ng/mL CLB (S/N=3) with favorable reproducibility and stability. Furthermore, this presented method could be feasible for determining CLB in the real pork samples.
•An applicable and sensitive electrochemical non-enzyme sensor was developed.•MoS2 decorated with uniform size AuNPs was successfully in-situ synthesized.•IVHemin was oxidized to O=FeIV–P at high potential and as high reactive oxidant.•The fabricated non-enzyme sensor was applied to detect CLB in real pork samples.
Molybdenum is a trace dietary element necessary for the survival of humans. Some molybdenum-bearing enzymes are involved in key metabolic activities in the human body (such as xanthine oxidase, ...aldehyde oxidase and sulfite oxidase). Many molybdenum-based compounds have been widely used in biomedical research. Especially, MoS2-nanomaterials have attracted more attention in cancer diagnosis and treatment recently because of their unique physical and chemical properties. MoS2 can adsorb various biomolecules and drug molecules via covalent or non-covalent interactions because it is easy to modify and possess a high specific surface area, improving its tumor targeting and colloidal stability, as well as accuracy and sensitivity for detecting specific biomarkers. At the same time, in the near-infrared (NIR) window, MoS2 has excellent optical absorption and prominent photothermal conversion efficiency, which can achieve NIR-based phototherapy and NIR-responsive controlled drug-release. Significantly, the modified MoS2-nanocomposite can specifically respond to the tumor microenvironment, leading to drug accumulation in the tumor site increased, reducing its side effects on non-cancerous tissues, and improved therapeutic effect. In this review, we introduced the latest developments of MoS2-nanocomposites in cancer diagnosis and therapy, mainly focusing on biosensors, bioimaging, chemotherapy, phototherapy, microwave hyperthermia, and combination therapy. Furthermore, we also discuss the current challenges and prospects of MoS2-nanocomposites in cancer treatment.
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•MoS2 with a large specific surface area can combine a variety of molecules to form a multifunctional nano-platform.•MoS2 with excellent optical absorption and photothermal conversion efficiency can be used in cancer therapy and bioimaging.•MoS2-nanocomposite can specifically respond to the tumor microenvironment and reduce side effects on non-cancerous tissues.
Phloretin (PHL) is an abundant dietary flavonoid possessing several pharmacological activities but with poor aqueous solubility and low bioavailability. Herein, two new cocrystals of ...phloretin-nicotinamide (PHL-NIC) and phloretin-isonicotinamide (PHL-INM) have been synthesized and characterized by various analytical methods. Two cocrystals exhibited different crystal packing and intermolecular interactions. Strong photoluminescence was observed in the PHL-NIC cocrystal while not in the PHL-INM cocrystal and pure PHL. Density functional theory (DFT) calculations were conducted to interpret the distinct photoluminescent behavior between the cocrystals. Both cocrystals exhibited enhanced dissolution performance in comparison with the pure PHL. This study demonstrates that cocrystallization is a powerful strategy to tune the physical properties of functional organic solids.
The high prevalence of β-thalassemia indicates the severe medical burden in Guangxi province in China. Millions of thousands of prenatal women with healthy or thalassemia-carrying fetuses received an ...unnecessary prenatal diagnosis. We designed a prospective single-center proof-of-concept study to evaluate the utility of a noninvasive prenatal screening method in the stratification of beta-thalassemia patients before invasive procedures.
Next-generation and optimized pseudo-tetraploid genotyping-based methods were utilized in preceding invasive diagnosis stratification to predict the mater-fetus genotype combinations in cell-free DNA, which is from maternal peripheral blood. Populational linkage disequilibrium information with additional neighboring loci to infer the possible fetal genotype. The concordance of the pseudo-tetraploid genotyping with the gold standard invasive molecular diagnosis was used to evaluate the effectiveness of this method.
127 β-thalassemia carrier parents were consecutively recruited. The total genotype concordance rate is 95.71%. The Kappa value was 0.8248 for genotype combinations and 0.9118 for individual alleles.
This study offers a new approach to picking out the health or carrier fetus before invasive procedures. It provides valuable novel insight into patient stratification management on β-thalassemia prenatal diagnosis.
Luminescent bulk crystals exhibit fewer grain boundaries and defects compared with conventional microsized powdery ones. Herein, targeting Mn
-activated fluoride crystals with a sharp line-type red ...luminescence spectrum, we propose a new cooling-induced crystallization method to grow the fluoride crystals. By this new method, we successfully grew millimeter-sized K
MnF
:Si
, NH
crystals, featuring an AE
(absorption efficiency) of 93.5% and an EQE
(external quantum efficiency) of 68.9%, which are among the best values for Mn
-activated fluoride red phosphors. The influence of doping Si
and/or NH
in K
MnF
on the local coordination structure and luminescence properties was studied. The anomalous thermal quenching behaviors were discussed, the luminescence decay from the excited state was compared, and the origin for the high quantum efficiencies was analyzed.
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