Preparation, <i>in vitro</i> degradability, cytotoxicity, and <i>in vivo</i> biocompatibility of porous hydroxyapatite whisker-reinforced poly(L-lactide) biocomposite scaffolds

<p>Biodegradable and bioactive scaffolds with interconnected macroporous structures, suitable biodegradability, adequate mechanical property, and excellent biocompatibility have drawn increasing attention in bone tissue engineering. Hence, in this work, porous hydroxyapatite whisker-reinforced poly(L-lactide) (HA-w/PLLA) composite scaffolds with different ratios of HA and PLLA were successfully developed through compression molding and particle leaching. The microstructure, <i>in vitro</i> mineralization, cytocompatibility, hemocompatibility, and <i>in vivo</i> biocompatibility of the porous HA-w/PLLA were investigated for the first time. The SEM results revealed that these HA-w/PLLA scaffolds possessed interconnected pore structures. Compared with porous HA powder-reinforced PLLA (HA-p/PLLA) scaffolds, HA-w/PLLA scaffolds exhibited better mechanical property and <i>in vitro</i> bioactivity, as more formation of bone-like apatite layers were induced on these scaffolds after mineralization in SBF. Importantly, <i>in vitro</i> cytotoxicity displayed that porous HA-w/PLLA scaffold with HA/PLLA ratio of 1:1 (HA-w₁/PLLA₁) produced no deleterious effect on human mesenchymal stem cells (hMSCs), and cells performed elevated cell proliferation, indicating a good cytocompatibility. Simultaneously, well-behaved hemocompatibility and favorable <i>in vivo</i> biocompatibility determined from acute toxicity test and histological evaluation were also found in the porous HA-w₁/PLLA₁ scaffold. These findings may provide new prospects for utilizing the porous HA whisker-based biodegradable scaffolds in bone repair, replacement, and augmentation applications.</p

Additional file 1 of Decreased influenza vaccination coverage among Chinese healthcare workers during the COVID-19 pandemic

Additional file 1: Questionnair

Additional file 2 of Decreased influenza vaccination coverage among Chinese healthcare workers during the COVID-19 pandemic

Additional file 2: Table S1. Characteristics of HCWs surveyed and in China Health Statistics Yearbook 2021

Stabilization of lead in incineration fly ash by moderate thermal treatment with sodium hydroxide addition

<div><p>Municipal solid waste (MSW) incineration fly ash (IFA) can be potentially reused as a substitute for some raw materials, but treatment for detoxification is indispensable owing to high contents of heavy metals in fly ash. In the present work, due to excessive leaching concentration of lead (Pb), a moderate thermal treatment with sodium hydroxide (NaOH) addition was employed to stabilize Pb in IFA. The moderate thermal treatment was performed under relatively low temperature ranging from 300 to 500°C and at retention time from 1 to 3 h with NaOH addition in a range of 1 to 9%. Leaching results showed that leaching concentrations of Pb in IFA leachates decreased below the standard for hazardous waste identification (5 mg/L) in China under all treatment scenarios. With the increase of temperature, retention time and the amount of NaOH, the concentration of Pb were further suppressed in IFA leachates. Especially, at 500°C for 3 h with 9% NaOH addition, the concentration of Pb dropped to 0.18 mg/L, which was below the standard for sanitary landfill (0.25 mg/L) in China. In thermal process, needle-like crystallites melted to form granules and clumps with compacter structure and less pores. After the thermal treatment, water-soluble and exchangeable fractions of Pb significantly decreased. Therefore, the thermal treatment coupled with NaOH could be applied to realize the environmentally sound management of MSW IFA.</p></div

TCLP leaching concentrations of Pb as a function of the amount of NaOH addition.

<p>TCLP leaching concentrations of Pb as a function of the amount of NaOH addition.</p

The experimental scheme of thermal treatment process.

<p>The experimental scheme of thermal treatment process.</p

TCLP leaching concentrations of Pb in different treated residues.

<p>TCLP leaching concentrations of Pb in different treated residues.</p

Experimental conditions of sequential extraction procedure.

<p>Experimental conditions of sequential extraction procedure.</p

Distribution pattern of Pb in (a) raw IFA; (b) R539.

<p>Distribution pattern of Pb in (a) raw IFA; (b) R539.</p

Map of Chinese provinces conducting influenza surveillance (<i>n</i> = 30).

<p>Dots indicate the location of the capital city in each province. A total of 193 hospitals participate in disease surveillance, representing 88 cities. Colors illustrate different climatic domains (black, cold-temperate; blue, mid-temperate; green, warm-temperate; orange, subtropical; red, tropical). Different symbols indicate the type of surveillance scheme (circles, year-round surveillance; triangles, Oct through Mar surveillance).</p