Hierarchically Porous Implants Orchestrating a Physiological Viscoelastic and Piezoelectric Microenvironment for Bone Regeneration.

The extracellular matrix microenvironment of bone tissue comprises several physiological cues. Thus, artificial bone substitute materials with a single cue are insufficient to meet the demands for bone defect repair. Regeneration of critical-size bone defects remains challenging in orthopedic surgery. Intrinsic viscoelastic and piezoelectric cues from collagen fibers play crucial roles in accelerating bone regeneration, but scaffolds or implants providing integrated cues have seldom been reported. In this study, it is aimed to design and prepare hierarchically porous poly(methylmethacrylate)/polyethyleneimine/poly(vinylidenefluoride) composite implants presenting a similar viscoelastic and piezoelectric microenvironment to bone tissue via anti-solvent vapor-induced phase separation. The viscoelastic and piezoelectric cues of the composite implants for human bone marrow mesenchymal stem cell line stimulate and activate Piezo1 proteins associated with mechanotransduction signaling pathways. Cortical and spongy bone exhibit excellent regeneration and integration in models of critical-size bone defects on the knee joint and femur in vivo. This study demonstrates that implants with integrated physiological cues are promising artificial bone substitute materials for regenerating critical-size bone defects.

Regulating Polysulfide Diffusion and Deposition via Rational Design of Core-Shell Active Materials in Li-S Batteries.

Polar host materials with strong adsorption capacity of polysulfides are designed to limit the shuttle effect in sulfur cathodes. However, a critical problem is to control diffusion and deposition of lithium polysulfides during cycling, which significantly impacts cycling stability and sulfur utilization. Here, we report using a sequential adsorption-guided self-assembly to design two types of core-shell sulfur particles with opposite polysulfide adsorption gradients to explore quantitatively the regulation of polysulfide diffusion and deposition. We show that a positive core-shell design of sulfur particles (PCSD@SP), i.e., polysulfide adsorption capability decreasing from the interior to the exterior of the host, is more effective in restricting polysulfide diffusion and regulating polysulfide deposition than the negative core-shell counterpart (NCSD@SP). As a result, the PCSD@SP electrode with a sulfur loading of 7 mg cm-2 exhibits a stable areal capacity of 6 mAh cm-2 over 130 cycles at 0.2C. At intermittent discharge/charge, the PCSD@SP electrode retains excellent stability compared with the NCSD@SP. We conclude that rational design of positive core-shell active materials can be used to regulate polysulfide diffusion and deposition to boost electrochemical reaction dynamics and performance. The reported findings will be of immediate benefit to a range of researchers in the design of high-performance lithium-sulfur batteries.

Tailoring Crystalline Morphology by High-Efficiency Nucleating Fiber: Toward High-Performance Poly(l-lactide) Biocomposites.

In this work, a high-melting-point poly(l-lactide) fiber (hPLLA fiber) with high-efficiency nucleation activity was prepared and introduced into PLLA matrix to prepare fully biodegradable PLLA biocomposites. The highly active nucleating surfaces of the hPLLA fiber induced chain ordering and lamellar organization, leading to a preferable formation of well-organized PLLA transcrystallinity at the surface of the hPLLA fiber under quiescent conditions. The construction of such compact transcrystallinity increased the crystallinity and enhanced the interfacial adhesion, which largely promoted heat resistance, tensile strength, and barrier property of PLLA biocomposites at a low content of hPLLA fiber. With the addition of 1 wt % hPLLA fiber, the storage modulus of the PLLA biocomposite was enhanced by 82 times from 4 to 330 MPa at 80 °C and the oxygen permeability coefficient and water permeability coefficient were decreased by 52 and 51% to be 5.9 × 10-15 cm3·cm/cm2·s·Pa and 4.5 × 10-14 g·cm/cm2·s·Pa, respectively, compared with those of pure PLLA. Moreover, the transparency of PLLA was maintained with the incorporation of hPLLA fiber. Thus, this strategy paved a new way to prepare high-performance and fully biodegradable biocomposites.

[Sero-epidemiological survey on general community population to understand the infection status after the first wave of pandemic 2009 H1N1 influenza in Guangdong province].

OBJECTIVE: To understand the infection status of pandemic 2009 H1N1 influenza after the first epidemic wave and to estimate the infected population. METHODS: Multi-stage stratified random sampling was introduced with 4500 subjects chosen in Guangdong province. 1500 people were selected from 5 districts (3 streets were selected in every district) in Guangzhou city which was representing the large cities. 1500 people were respectively selected from medium-sized city and rural areas, including 20 cities (1 county or district was selected in every city, at least 1 street or town was selected in every county or district respectively and then 1 - 2 residential area or county was selected in every street or township, respectively). Every sample was selected in accordance with the principle of random sampling, excluding those who had injected with novel H1N1 vaccine. We used hemagglutination inhibition test to understand the serum antibody level of novel H1N1, with title of 1:40 as positive. RESULTS: A number of 4319 specimens, distributed in 21 cities, 25 counties, 85 streets or townships, 144 residential areas, were tested, with an overall positive rate as 22.82% (985/4319). The positive rate of those who had no symptoms of cold since June was 23.47% (471/2007). The positive rate of those who had fever, cough or sore throat was 26.25% (714/2720). The positive rate of those who had influenza-like illness (ILI) was 29.69% (337/1135). CONCLUSION: The infection rate in the first epidemic wave of the novel influenza A (H1N1) pandemic in Guangdong province was 22.82% (985/4317). Based on the number of residents in Guangdong province, the number of natural was estimated to have reached 21.78 million.

[Investigation of a norovirus outbreak through contaminated centralized water supply system].

OBJECTIVE: To investigate the etiology and source of an infectious diarrhea outbreak and control the epidemic. METHODS: Through the retrospective cohort study, we had surveyed all the residents who complained symptoms of diarrhea or vomiting since Nov. 20th,2007 from the five villages in the north of town Y, and collected hygiene information on the water supply system of the five villages, the environment information of three villages and hygiene information of some case-indexed families, and tested the etiological biomarker, including nucleoside acid of norovirus through Real-time PCR and nested PCR technologies. RESULTS: From Nov. 24th to Dec. 3th in 2007, 435 diarrhea or vomiting cases were found in the north of Y town, where tap water A was supplied for daily use. The attack rate was 12.93%. The diarrhea cases were distributed among all country groups who has used tap water A and the attack rate was ranged from 5.21% (20/384) to 21.23% (100/471). Drinking the tap water A was significantly associated with an increased risk of infection (RR = 9.246, 95% CI: 6.25 -13.68). About 85.9% (262/ 305) of the cases were from Nov. 25th to 27th. An investigation of a country of S2 group showed that the incidence of different age groups was distributed as the following: 0 - year-old 20.0% (3/15); 10 - year-old 17.3% (9/52); 20 - year-old 15.2% (16/105); older than 60 year-old 23.3% (7/30). No statistical significance was identified between age and infection(chi2 = 1.15, P >0.05). Most of the patients were not serious and well prognostic, and no hospitalized or dead cases were reported. On site investigation and daily water quality monitoring showed that disinfection procedures were not strictly followed. The monitoring data also indicated the bacteriology index of tap water A was disqualified. The test of Salmonella, Shigella and Staphylococcus aureus were negative in two vomit and one stool samples from patients. Three specimens by Real-time PCR, and six by nested PCR were positive for norovirus among the three feces and three anal swabs samples. With the drinking water sterilization and health education, the epidemic had been controlled rapidly and effectively. CONCLUSION: The epidemic was a diarrhea outbreak that might be caused by norovirus through drinking the contaminated tap water A.

[Comparison between laparoscopic pyloromyotomy and open pyloromyotomy for infants with congenital hypertrophic pyloric stenosis]

OBJECTIVE: To compare the efficacy of laparoscopic pyloromyotomy with open pyloromyotomy in treatment of congenital hypertrophic pyloric stenosis(CHPS). METHODS: Fifteen patients (age 20%ape;90 days, body weight 2.5 approximate, equals 5.0 kg) with CHPS underwent laparoscopic pyloromyotomy (Group I) and 10 patients (age 26 approximate, equals 90 days, body weight 2.8 approximate, equals 4.5 kg) with CHPS underwent open pyloromyotomy (Group II). Ambulatory 24 hr esophageal pH metry and gastroesophageal mamometry were studied in two groups before and after surgery. RESULTS: All patients presented gastroesophageal reflux (GER) before operation and all reflux parameters were significantly decreased after operation (P<0.01). There was no significant difference between two groups in reflux parameters after surgery. Intragastric pressure (GP) significantly reduced in two groups after operation(3.83+/-1.45)mmHg compared with (2.38+/-0.54)mmHg P<0.01 in Group I,(4.52+/-1.96)mmHg compared with (2.38+/-0.72)mmHg P<0.05 in Guoup II). There was no significant difference in lower esophageal sphincter pressure (LESP), lower esophageal sphincter length (LESL) before and after operation in two groups. The mean operative time for Group I was (32+/-19) mins, which was close to that of Group II after an initial trail. Oral feeding was started 6 h postoperatively in Group I, which was earlier than that in Group II. No technical failures and complications in Group I were encountered. One wound infection and dehiscense was seen in Group II. CLUSION: Laparoscopic pyloromyotomy for infantile hypertrophic pyloric stenosis is safe and feasible, which has lesser complication and similar effect of antireflux as open pyloromyotomy.