Biosorption of hexavalent chromium from aqueous solution by polyethyleneimine-modified ultrasonic-assisted acid hydrochar from Sargassum horneri.

In this study, an efficient route to synthesizing polyethyleneimine-modified ultrasonic-assisted acid hydrochar (PEI-USAH) is developed and reported. Ultrasonic irradiation technique was used as surface modification method to shorten the crosslinking reaction for hydrochar and polyethyleneimine (PEI). The PEI-USAH showed an excellent adsorption capacity for Cr(VI) from aqueous solution. The physicochemical properties of this PEI-modified adsorbent were comparatively characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller analysis and CNHS analysis. The effects of contact time, initial pH, and biosorbent dose on adsorption capacities were investigated. The batch adsorption experiments showed that PEI-USAH possessed the maximum adsorption capacities of 94.38 mg/g and 330.84 mg/g for initial Cr(VI) concentration of 100 mg/L and 500 mg/L, respectively. Furthermore, this adsorption process could be fitted to Langmuir adsorption and described by the pseudo second order kinetic model. Based on the above findings, PEI-USAH could be used as a potential adsorbent for removal of Cr(VI) from wastewater.

Galla chinensis Compounds Remineralize Enamel Caries Lesions in a Rat Model.

OBJECTIVES: To investigate the effect of Galla chinensis chemical compounds on enamel caries remineralization in rats. METHODS: A total of 40 rats were inoculated with Streptococcus sobrinus 6715 and fed a cariogenic diet (Keyes 2000). The rats were randomly divided into 4 groups and treated topically twice a day with each of the following extracts (or control) for 5 weeks: distilled and deionized water (DDW, negative control); 1,000 ppm NaF (positive control); 4,000 ppm G. chinensis crude aqueous extract (GCE), or 4,000 ppm gallic acid (GA). After the experimental period, Keyes' caries diagnosis and scoring technique was applied as a preliminary evaluation on the molar teeth. For more accurate remineralization data, the residual enamel volume of the first molar and the mineral density (MD) of the enamel were further analyzed by micro-CT. RESULTS: The severity of molar enamel caries decreased in the following order of treatment groups: DDW > GA > GCE > NaF (p < 0.05). In addition, the residual first molar enamel volume and MD values increased in the order of DDW, GA, GCE and NaF treatment groups (p < 0.05). In most molars, remineralization layers were observed on the surface of lesions. CONCLUSION: G. chinensis compounds remineralize enamel caries lesions in a rat model.

Biodegradable film mulching increases soil microbial network complexity and decreases nitrogen-cycling gene abundance.

Biodegradable plastic films have emerged as a substitute for conventional plastic films. Nevertheless, responses of plant-associated microbiomes to the application of biodegradable film mulching at field scale have received little attention. A field experiment was conducted to assess the influence of different film mulching treatments on various microbial attributes and nitrogen (N) cycling functional genes in bulk and rhizosphere soils. Biodegradable film mulching raised the bacterial Shannon index in bulk soils but not in rhizosphere soils. Biodegradable film mulching has led to an increase in the complexity and connectivity of microbial networks, as well as an enhancement in the positive association among microorganisms owing to raised soil nutrients and increased crop biomass. In biodegradable film-treated soils, both bacterial and fungal communities were primarily influenced by stochastic processes associated with dispersal limitation. Moreover, conventional plastic film mulching increased denitrification, anammox, N fixation, and dissimilatory nitrate-reduction (DNRA) gene abundance in bulk soils. In rhizosphere soils, biodegradable film mulching reduced nitrification, denitrification, anammox, N fixation, and DNRA gene abundance. Furthermore, keystone genera (e.g., Nitrosospira, Truepera, Adhaeribacter, Opitutus, and Fusarium) were affected by edaphic variables, contributing to decreased N-cycling gene abundance in biodegradable film-treated soils. Collectively, biodegradable film mulching transformed soil microbiome assembly and functional adaptation, and soil nutrient availability and plant biomass were the critical factors influencing the microbial community. These findings present a novel perspective on the diverse impacts of biodegradable and conventional film mulching on soil microbiome and N-cycling processes.

Exposure risk to rural Residents: Insights into particulate and gas phase pesticides in the Indoor-Outdoor nexus.

Rural residents are exposed to both particulate and gaseous pesticides in the indoor-outdoor nexus in their daily routine. However, previous personal exposure assessment mostly focuses on single aspects of the exposure, such as indoor or gaseous exposure, leading to severe cognition bias to evaluate the exposure risks. In this study, residential dust and silicone wristbands (including stationary and personal wearing ones) were used to screen pesticides in different phases and unfold the hidden characteristics of personal exposure via indoor-outdoor nexus in intensive agricultural area. Mento-Carlo Simulation was performed to assess the probabilistic exposure risk by transforming adsorbed pesticides from wristbands into air concentration, which explores a new approach to integrate particulate (dust) and gaseous (silicone wristbands) pesticide exposures in indoor and outdoor environment. The results showed that particulate pesticides were more concentrated in indoor, whereas significantly higher concentrations were detected in stationary outdoor wristbands (p < 0.05). Carbendazim and chlorpyrifos were the most frequently detected pesticides in dust and stationary wristbands. Higher pesticide concentration was found in personal wristbands worn by farmers, with the maximum value of 2048 ng g-1 for difenoconazole. Based on the probabilistic risk assessment, around 7.1 % of farmers and 2.6 % of bystanders in local populations were potentially suffering from chronic health issues. One third of pesticide exposures originated mainly from occupational sources while the rest derived from remoting dissipation. Unexpectedly, 43 % of bystanders suffered the same levels of exposure as farmers under the co-existence of occupational and non-occupational exposures. Differed compositions of pesticides were found between environmental samples and personal pesticide exposure patterns, highlighting the need for holistic personal exposure measurements.

Experts consensus on the procedure of dental operative microscope in endodontics and operative dentistry.

The dental operative microscope has been widely employed in the field of dentistry, particularly in endodontics and operative dentistry, resulting in significant advancements in the effectiveness of root canal therapy, endodontic surgery, and dental restoration. However, the improper use of this microscope continues to be common in clinical settings, primarily due to operators' insufficient understanding and proficiency in both the features and established operating procedures of this equipment. In October 2019, Professor Jingping Liang, Vice Chairman of the Society of Cariology and Endodontology, Chinese Stomatological Association, organized a consensus meeting with Chinese experts in endodontics and operative dentistry. The objective of this meeting was to establish a standard operation procedure for the dental operative microscope. Subsequently, a consensus was reached and officially issued. Over the span of about four years, the content of this consensus has been further developed and improved through practical experience.

Effects of plastic residues and microplastics on soil ecosystems: A global meta-analysis.

Plastic pollution is one of the global pressing environmental problems, threatening the health of aquatic and terrestrial ecosystems. However, the influence of plastic residues and microplastics (MPs) in soil ecosystems remains unclear. We conducted a global meta-analysis to quantify the effect of plastic residues and MPs on indicators of global soil ecosystem functioning (i.e. soil physicochemical properties, plant and soil animal health, abundance and diversity of soil microorganisms). Concentrations of plastic residues and MPs were 1-2700 kg ha-1 and 0.01-600,000 mg kg-1, respectively, based on 6223 observations. Results show that plastic residues and MPs can decrease soil wetting front vertical and horizontal movement, dissolved organic carbon, and total nitrogen content of soil by 14%, 10%, 9%, and 7%, respectively. Plant height and root biomass were decreased by 13% and 14% in the presence of plastic residues and MPs, while the body mass and reproduction rate of soil animals decreased by 5% and 11%, respectively. However, soil enzyme activity increased by 7%441% in the presence of plastic residues and MPs. For soil microorganisms, plastic residues and MPs can change the abundance of several bacteria phyla and families, but the effects vary between different bacteria.

Remote multi-color excitation using femtosecond propagating surface plasmon polaritons in gold films.

We demonstrate dual-color nonlinear excitation of quantum dots positioned onto a gold film at distances up to 40 µm away from a micrometer sized focused laser spot. We attribute the observed remote nonlinear signal to the excitation of two independent surface plasmon polariton (SPP) modes excited at the laser spot in the gold film, which subsequently propagate in a collinear fashion to a distant site and provide the surface field required for nonlinear excitation of the target. This scheme decouples the illuminating photon flux from surface plasmon mediated nonlinear excitation of the target, which provides more control of unwanted heating effects at the target site and represents an attractive approach for surface-mediated femtosecond nonlinear examinations of molecules.

[The relationship between Streptococcus sobrinus and rampant caries in children].

PURPOSE: To explore the relations between Streptococcus sobrinus (S. Sobrinus) and rampant caries in children. METHODS: Based on previous investigation result for rampant caries in Zhengzhou city, 66 children aged 3-5 years were selected by random sampling, and divided into 3 groups of rampant caries, high dental caries and no caries, 22 cases in each group. The final identification of S. mutans and S. sobrinus were performed after using culture medium TYCSB to operate preliminary screening of Streptococcus mutans (S. Mutans) and S. Sobrinus with polymerase chain reaction(PCR) combined with physiological and biochemical identification. SPSS10.0 software package was used to compare the detection rate and mean values of S.mutans and S.sobrinus in the experimental group and the control group. RESULTS: It was found that single S. sobrinus without S. mutans was not detected from dental plaque in each group. The detection rate of S. mutans in group of rampant caries was higher than in group of high dental caries, but there was no significant difference (P>0.05). The difference of detection rate of S. sobrinus between the two groups and the detection rate of S. mutans between group of rampant caries and group without caries was significant(P<0.05). The difference of the detection rate of S. sobrinus between group of rampant caries and group without caries was also significant(P<0.01). The incidence of rampant caries, DMFT, DMFS, smooth-surface caries among the sample with both of S. sobrinus and S. mutans detected and the sample only with S. mutans and the sample without S. sobrinus and S. mutans were significantly different (P<0.01). CONCLUSIONS: The main pathogenic bacteria of rampant caries in children are S. mutans and S. sobrinus. The incidence of rampant caries was related to S. sobrinus, which had synergic effect on the occurrence and development of rampant caries in children.

Effects of dentin tubule occlusion by dentifrice containing a PVM/MA bioadhesive copolymer in a silica base.

OBJECTIVE: To study the effectiveness of a dentifrice containing polymethyl vinyl ether-maleic acid (PVM/MA) copolymer in a silica base in occluding dentin tubules for treatment of dentin sensitivity. METHODS: Thirty-two human dentin discs were divided into two groups and brushed in the morning for 30s each to study the dentifrices with and without PVM/MA copolymer. Dentin tubule occlusion and dentin permeability were evaluated with a focus variation three dimensional vertical scanning microscope (IFM) and electrochemical impedance spectroscopy (EIS). After second brushing for 30s in the afternoon the dentin discs were immersed in saliva for 16 h and then subjected to erosion using orange juice for 10 min. The effects of saliva and orange juice on tubule occlusion used in the study of dentifrices were further evaluated with IFM. RESULTS: On average 97.7% of the dentin tubules were occluded after brushing in the PVM/MA group, as compared to 13.3% in the control group (p<0.0001). EIS showed that the impedance of the dentin disc increased after treatment with PVM/MA but not in the control group (p<0.05). After 16 h of storage in saliva and 10 min of erosion by orange juice, 86% of the dentin tubules remained occluded in the PVM/MA treated dentifrice. The sizes of the tubule openings were increased after orange juice erosion in the control group but not in the PVM/MA group. CONCLUSION: Dentifrice containing PVM/MA copolymer in a silica base effectively occluded dentin tubules. The intra-tubular plugs were resistant to saliva and orange juice challenges.

Preventive effects of dentifrice containing 5000ppm fluoride against dental erosion in situ.

OBJECTIVE: To evaluate the effectiveness of a dentifrice with 5000ppm fluoride in preventing dental erosion by orange juice in situ in comparison to a control dentifrice with 1450ppm fluoride. METHODS: This was a double-blind and randomized clinical study with a cross-over design. Sixteen subjects wore an intra-oral appliance containing two enamel disks with an exposed surface of approximately 2mm×5mm. Enamel disks in the study group were treated with a dentifrice with 5000ppm fluoride and in the control group with 1450ppm fluoride. The subjects rinsed with slurries of study dentifrices for one minute before immersing the enamel disks in 250ml orange Juice four times in an 8-h period daily. The treatment procedure was repeated for three 5-day phases for each dentifrice. Enamel erosion was measured after each 5-day treatment phase using a focus-variation 3D scanning microscopy. Medians and inter-quartile ranges (IQR) of mean erosion depth were compared between the groups. RESULTS: The mean erosion depths of enamel varied greatly amongst the subjects. Enamel treated with 5000ppm fluoride had less erosion (median 5.7µm, IQR 4.5µm) as compared to the control (median 12.6µm, IQR 12.3µm) after 15 days of fluoride treatment and erosive challenge cycles (p<0.05). CONCLUSIONS: Enamel treated with 5000ppm fluoride had significantly improved resistance to erosion by orange juice. Periodic application of 5000ppm fluoride may be beneficial in individuals at risk of acidic erosion associated with soft drink consumptions.

[Influence of implant-abutment connection mode on stress distribution in peri-implant bone].

OBJECTIVE: To investigate the influence of butt joint connection and platform switching design of implant-abutment connection on the stress distribution in peri-implant bone. METHODS: Three-dimensional finite element models of implant-supported mandibular first molar with different implant-abutment connections were computed by COSMOSM 2.85. Traditional butt joint connection was used in model A and platform switching design in model B. Loading conditions were a vertical load of 200 N and inclined load of the same magnitude at 45 degrees to the vertical axis of the implant. Stress distribution in peri-implant bone and von Mises stresses at the same point of buccal and lingual implant-bone interfaces in two models were compared. RESULTS: Stresses concentrated in peri-implant cortical bone at the neck of implants on the buccal and lingual sides; maximum von Mises stresses under inclined load were higher than those under vertical load. Maximum von Mises stress in bone was 11.61 MPa in model A and 7.15 MPa in model B under vertical load, and 22.07 MPa in model A and 11.87 MPa in model B under inclined load respectively. Von Mises stresses decreased as the distance from implant-abutment junction increased and the most obvious change occurred at the interface between cortical bone and spongy bone. Von Mises stresses at the same points of buccal and lingual implant-bone interfaces in model A were higher than those in model B. CONCLUSIONS: Compared with butt joint connection, platform switching design improved the stress distribution and decreased the maximum stresses in peri-implant bone around implant cervix.

[Magnetic resonance imaging of the upper airway structure of children with sleep disordered breathing].

OBJECTIVE: To investigate the upper airway structure of sleep-disordered breathing children. METHODS: Seventy three children with obstructive sleep apnea hypopnea syndrome (OSAHS), 53 children with primary snoring (PS) and 40 control subjects underwent pharyngeal magnetic resonance imaging (MRI). Upper airway structure images were analyzed and measured. RESULTS: The cross-section area of the nasopharyngeal and palatopharyngeal airway in subjects with OSAHS and PS are smaller (P < 0.01) than that of the control group. The cross section area of OSAHS patients are smaller than that of PS subjects (P < 0.01). The above parameter of oropharyngeal airway in OSAHS patients is smaller than that of control group (P < 0.01), but no statistic difference compared with that of PS subjects. The cross-section area and length of the adenoid in OSAHS group are bigger and longer than that of PS group (P < 0.01) and bilateral tonsils are larger (P < 0.01); in OSAHS patients the cross-section area of the soft palate is larger and the length of the soft palate is longer (P < 0.01) than that of PS group, while this parameter of PS group is similar to that of the control group. And the maximum width of the soft palate, the cross-section area of bilateral fat pad, bilateral pterygoid and tongue are similar among OSAHS, PS and the control group. The skeletal measurement: the length of H-C2C3 in subjects with OSAHS is longer (P < 0.01); The angle(alpha) in OSAHS patients is smaller (P < 0.01) than that of other 2 groups. The angle (beta), the cross-section area of the mandible, the spine-clivus oblique, the length of the hard palate and the distance of the mandible are similar among the three groups. CONCLUSIONS: In children with OSAHS or PS, the upper airway is restricted by both the adenoid and tonsils; however, the soft palate is also larger in OSAHS, adding further restriction. Otherwise, downward movement of the hyoid bone and decreasing of the angle (alpha) in OSAHS influence laryngopharynx airway. MRI is of clinical significance for evaluating OSAHS children's upper airway.

[Clinical results of breast augmentation with polyacrylamide hydrogel injection].

OBJECTIVE: To investigate the complications in 16 patients who had breast augmentation with polyacrylamide hydrogel injection. The distribution and late changes of the injected material was observed. METHODS: The physical signs and symptoms of the 16 patients were classified. Ultrasound and infrared examinations or MRI were used in some cases. RESULTS: Two patients had operations for extraction. The injection material was distributed in the muscles diffusely, or existed in the breast and subcutaneous tissue as many masses. CONCLUSION: The reliability of this injection method for breast augmentation is in doubt.