The objective of this study was to investigate the associations between selenium exposure and cancer risk. We identified 69 studies and applied meta-analysis, meta-regression and dose-response analysis to obtain available evidence. The results indicated that high selenium exposure had a protective effect on cancer risk (pooled OR = 0.78; 95%CI: 0.73–0.83). The results of linear and nonlinear dose-response analysis indicated that high serum/plasma selenium and toenail selenium had the efficacy on cancer prevention. However, we did not find a protective efficacy of selenium supplement. High selenium exposure may have different effects on specific types of cancer. It decreased the risk of breast cancer, lung cancer, esophageal cancer, gastric cancer, and prostate cancer, but it was not associated with colorectal cancer, bladder cancer, and skin cancer.
Gallium-based liquid metals (LMs),
with the combination of liquid
fluidity and metallic conductivity, are considered ideal conductive
components for flexible electronics. However, huge surface tension
and poor wettability seriously hinder the patterning of LMs and their
wider applications. Herein, a recyclable liquid-metal-microgel (LMM)
ink composed of LM droplets encapsulated into alginate microgel shells
is proposed. During the mechanical stirring process, the released
Ga3+ can cross-link with sodium alginate to form microgels
covering the surface of LM droplets, which exhibits shear-thinning
performance due to the formation and rupture of hydrogen bonds under
different stress conditions, making the LMM ink possess excellent
printability and superior adhesion to various substrates. Although
patterns printed with the LMM ink are not initially conductive, they
can be activated to recover conductivity by microstrain (<5%),
pressing, and freezing. Additionally, the activated LMM circuit exhibits
superior Joule heating behaviors and electrical performance in further
investigation, including excellent conductivity, significant resistance
response to strain with small hysteresis, great durability to nonplanar
forces, and so forth. Furthermore, smart electronic clothes were fabricated
and investigated by directly printing functional circuits on commercial
clothes with the LMM ink, which integrate multiple functions, including
tactile sensing, motion monitoring, human–computer interaction,
and thermal management.
L-Pipecolinic acid derived formamides have been developed as highly efficient and enantioselective Lewis basic organocatalysts for the reduction of N-aryl imines with trichlorosilane. Catalyst 4b afforded high isolated yields (up to 98%) and enantioselectivities (up to 96%) under mild conditions with an unprecedented substrate spectrum. Catalytic enantioselective reduction of imines represents one of the most important methods for preparing chiral amines, 1 a ubiquitous structural motif of natural products, drugs, and agrochemicals. Since the 1970s, considerable effort has been devoted to the development of this transformation, and remarkable progress has been made. 1,3 However, compared with the reduction of alkenes and ketones, relatively limited numbers of highly enantioselective procedures are currently available for the reduction of imines, and the development of efficient catalysts with high enantioselectivity has proven to be much more difficult. In particular, the highly enantio-selective catalyst with a satisfactorily broad substrate scope remains elusive. Factors contributing to the difficulty of this transformation include the difference in reactivity among imines containing different nitrogen substituents, the existence of acyclic imines as inseparable mixtures of E/Z
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