Open ocean particle flux variability from surface to seafloor

The sinking of carbon fixed via net primary production (NPP) into the ocean interior is an important part of marine biogeochemical cycles. NPP measurements follow a log‐normal probability distribution, meaning NPP variations can be simply described by two parameters despite NPP’s complexity. By analyzing a global database of open ocean particle fluxes, we show that this log‐normal probability distribution propagates into the variations of near‐seafloor fluxes of particulate organic carbon (POC), calcium carbonate, and opal. Deep‐sea particle fluxes at subtropical and temperate time‐series sites follow the same log‐normal probability distribution, strongly suggesting the log‐normal description is robust and applies on multiple scales. This log‐normality implies that 29% of the highest measurements are responsible for 71% of the total near‐seafloor POC flux. We discuss possible causes for the dampening of variability from NPP to deep‐sea POC flux, and present an updated relationship predicting POC flux from mineral flux and depth

Characteristics of Early-Onset vs Late-Onset Colorectal Cancer: A Review.

The incidence of early-onset colorectal cancer (younger than 50 years) is rising globally, the reasons for which are unclear. It appears to represent a unique disease process with different clinical, pathological, and molecular characteristics compared with late-onset colorectal cancer. Data on oncological outcomes are limited, and sensitivity to conventional neoadjuvant and adjuvant therapy regimens appear to be unknown. The purpose of this review is to summarize the available literature on early-onset colorectal cancer. Within the next decade, it is estimated that 1 in 10 colon cancers and 1 in 4 rectal cancers will be diagnosed in adults younger than 50 years. Potential risk factors include a Westernized diet, obesity, antibiotic usage, and alterations in the gut microbiome. Although genetic predisposition plays a role, most cases are sporadic. The full spectrum of germline and somatic sequence variations implicated remains unknown. Younger patients typically present with descending colonic or rectal cancer, advanced disease stage, and unfavorable histopathological features. Despite being more likely to receive neoadjuvant and adjuvant therapy, patients with early-onset disease demonstrate comparable oncological outcomes with their older counterparts. The clinicopathological features, underlying molecular profiles, and drivers of early-onset colorectal cancer differ from those of late-onset disease. Standardized, age-specific preventive, screening, diagnostic, and therapeutic strategies are required to optimize outcomes

Intra- and interband electron scattering in a hybrid topological insulator: Bismuth bilayer on bi2se3{\mathrm{bi}}_{2}{\mathrm{se}}_{3}

Contains fulltext : 135709.pdf (publisher's version ) (Open Access

Visualizing lithium-ion migration pathways in battery materials

10.1002/chem.201301504Chemistry - A European Journal194615535-15544CEUJ

Thermal Instability of β-Zn4Sb3: Insights from Transport and Structural Measurements

β-Zn4Sb3 exhibits poor thermal stability, with zinc-rich specimens recently shown to be more stable. In this work, temperature-dependent transport measurements [Seebeck coefficient (S) and electrical conductivity (σ)] between room temperature (RT) and 525 K were carried out on a zinc-poor specimen. The sequentially measured S and σ data in the same measurement cycle show sharp changes in their absolute values between 450 K and 500 K during the heating cycle, which is not retraced back during cooling. A repeat measurement carried out on the specimen after ~1 month again shows the sharp changes in the absolute values between 450 K and 500 K, indicating reversibility of the process. Temperature-dependent synchrotron measurements were further carried out between RT and 525 K. Formation of elemental Sb was observed beyond 400 K. Between 450 K and 500 K, movement of zinc from lattice to interstitial position is observed, which is also accompanied by the onset of ZnSb formation. The overall zinc content within the β-Zn4Sb3 phase is observed to increase with increasing temperature. These observations indicate that both the overall zinc content and the ZnI/ZnL ratio are crucial in stabilizing the β-Zn4Sb3 phase

Enhanced thermoelectric properties of Mg2Si by addition of TiO2 nanoparticles

The effects on the thermoelectric properties of Mg2Si when adding TiO2 nanoparticles have been evaluated experimentally. A batch of Mg2Si was prepared through direct solid state reaction and divided into portions which were mechanically mixed with different amounts of TiO2 nanoparticles ranging from 0.5 to 3 vol% and subsequently sintered to disks. All materials showed n-type conduction and the absolute value of the Seebeck coefficient was reduced with increasing amount of TiO2 added, while the electrical resistivity was greatly reduced. The thermal conductivity was surprisingly little affected by the addition of the nanoparticles. An optimum value of the thermoelectric figure-of-merit ZT = TS2 sigma/k was found for the addition of 1 vol% TiO2, showing almost three times higher ZT value than that of the pure Mg2Si. Larger TiO2 additions resulted in lower ZT values and with 3 vol% added TiO2 the ZT was comparable to the pure Mg2Si. The sintering process resulted in reduction or chemical reaction of all TiO2 to TiSi2 and possibly elemental titanium as well as reduced TiOx. The increased electrical conductivity and the decreased Seebeck coefficient were found due to an increased charge carrier concentration, likely caused by the included compounds or titanium-doping of the Mg2Si matrix. The low observed effect on the thermal conductivity of the composites may be explained by the relatively higher thermal conductivity of the included compounds, counter-balancing the expected increased grain boundary scattering. Alternatively, the introduction of compounds does not significantly increase the concentration of scattering grain boundaries