Achievement of waste sludge deep dehydration under acidic conditions with polydimethyldiallylammonium chloride and ferric chloride: performance and mechanism.

The biological treatment of wastewater generates a substantial amount of waste sludge that requires dewatering before final disposal. Efficient sludge dewatering is essential to minimize storage and transportation costs. In this study, the sludge conditioners polydimethyldiallylammonium chloride (PDMDAAC) and ferric chloride (FeCl3) were sequentially dosed, and the pH was adjusted to 3. As a result, the sludge moisture content (MC) was reduced to 59.4%, achieving deep dewatering. After conditioning, the tightly bound extracellular polymeric substances (TB-EPS) were reduced from 34.5 to 10.2 mg g-1 VSS, with the majority of the reduced fractions being composed of protein (PN). In contrast, soluble EPS increased more than 8 times. Subsequent studies revealed that the decrease in PN from TB-EPS primarily involved tryptophan and tyrosine proteins, accompanied by a significant reduction in the N-H and C[double bond, length as m-dash]C absorption peaks. These results highlight the critical role of TB-EPS dissolution in achieving deep dehydration, with the N-H in PN was identified as the key group influencing sludge dewatering. Combined with the changes in sludge particle size and morphology, the dewatering mechanism can be summarized as follows: PDMDAAC dissolves TB-EPS, simultaneously disrupting the floc structure and refining the sludge. Subsequently, FeCl3 reconstructs these elements, forming larger particle sizes. Finally, hydrochloric acid reduces TB-EPS once again, releasing bound water. This study offers alternative methods and new insights for achieving deep dewatering of waste sludge.

Evaluating STC2 gene RNA in peripheral blood serum of gastric cancer patients.

Cancer is one of the leading causes of death in the world. Invasive microscopic and endoscopic methods are not suitable for routine screening of gastric cancer. Therefore, the need for biomarkers that can detect quickly, efficiently, and with high sensitivity in the early stages of cancer is strongly felt. Stanniocalcin plays a role in regulating calcium and phosphorus in the body. In addition, it plays a role in neuron cell differentiation, angiogenesis, wound healing, fertility and embryo development, and cancer. This study investigated the level of expression of the Stanniocalcin 2 (STC2) gene in the serum of patients with gastric cancer. This case-control study was conducted on the samples of 60 patients with gastric cancer (cases) and 60 healthy individuals (controls). Peripheral blood samples from gastric cancer patients and volunteers as control groups were collected in tubes containing EDTA anticoagulant and were immediately subjected to serum separation. After centrifugation, serum RNA was extracted, and after cDNA synthesis, STC2 gene serum RNA level was measured by the Taq Man method and Real-time PCR using specific primers and probes. Then, the results of serum evaluations and clinicopathological information of patients and control group were collected along with the information obtained from reviewing patients' files and demographic findings, regulatory tables, and related charts. SPSS22 software was used to analyze descriptive data. According to the study results, the high expression of the STC2 gene was 31 cases in the case group and 13 cases in the control group. However, there was a significant relationship between the high expression of the STC2 gene and gastric cancer (p = 0.0001). However, there was no significant relationship between the gender of patients and high expression of the STC2 gene. However, the age of 35% of the patients was more than 65 years, and there was a significant relationship between the age of the patients and the high expression of the STC2 gene (P = 0.028). Although there was no significant relationship between the anatomical location of the cancer and the subtypes of the cancer and the high expression of the STC2 gene, there was a significant relationship between the degree of cancer differentiation and the high expression of STC2 gene (P<0.05). In general, STC2 can be used as a biomarker to determine the border and margins of the tumor. Analysis of STC2 gene expression during surgery can reduce surgical error in tumor removal and increase the success of surgery for tumor removal.

Characterization of Silk Fibroin/Chitosan 3D Porous Scaffold and In Vitro Cytology.

Bone tissue engineering is a powerful tool to treat bone defects caused by trauma, infection, tumors and other factors. Both silk fibroin (SF) and chitosan (CS) are non-toxic and have good biocompatibility, but are poor biological scaffolds when used alone. In this study, the microscopic structure and related properties of SF/CS composite scaffolds with different component ratios were examined. The scaffold material most suitable for osteoblast growth was determined, and these results offer an experimental basis for the future reconstruction of bone defects. First, via freeze-drying and chemical crosslinking methods, SF/CS composites with different component ratios were prepared and their structure was characterized. Changes in the internal structure of the SF and CS mixture were observed, confirming that the mutual modification between the two components was complete and stable. The internal structure of the composite material was porous and three-dimensional with a porosity above 90%. We next studied the pore size, swelling ratio, water absorption ratio, degradation and in vitro cell proliferation. For the 40% SF-60% CS group, the pore size of the scaffold was suitable for the growth of osteoblasts, and the rate of degradation was steady. This favors the early adhesion, growth and proliferation of MG-63 cells. In addition to good biocompatibility and satisfactory cell affinity, this material promotes the secretion of extracellular matrix materials by osteoblasts. Thus, 40% SF-60% CS is a good material for bone tissue engineering.

Preparation and characterization of genipin-cross-linked silk fibroin/chitosan sustained-release microspheres.

We report the effects of distinct concentrations of genipin and silk fibroin (SF):chitosan (CS) ratios on the formation of SF-CS composite microspheres. We selected microspheres featuring an SF:CS ratio of 1:1, encapsulated various concentrations of bovine serum albumin (BSA), and then compared their encapsulation efficiency and sustained-release rate with those of pure CS microspheres. We determined that the following five groups of microspheres were highly spherical and featured particle sizes ranging from 70 µm to 147 µm: mass ratio of CS:SF =1:0.5, 0.1 g or 0.5 g genipin; CS:SF =1:1, 0.05 g or 1 g genipin; and CS:SF =1:2, 0.5 g genipin. The microspheres prepared using 1:1 CS:SF ratio and 0.05 g genipin in the presence of 10 mg, 20 mg, and 50 mg of BSA exhibited encapsulation efficiencies of 50.16%±4.32%, 56.58%±3.58%, and 42.19%±7.47%, respectively. Fourier-transform infrared spectroscopy (FTIR) results showed that SF and CS were cross-linked and that the α-helices and random coils of SF were converted into ß-sheets. BSA did not chemically react with CS or SF. Moreover, thermal gravimetric analysis (TGA) results showed that the melting point of BSA did not change, which confirmed the FTIR results, and X-ray diffraction results showed that BSA was entrapped in microspheres in a noncrystalline form, which further verified the TGA and FTIR data. The sustained-release microspheres prepared in the presence of 10 mg, 20 mg, and 50 mg of BSA burst release 30.79%±3.43%, 34.41%±4.46%, and 41.75%±0.96% of the entrapped BSA on the 1st day and cumulatively released 75.20%±2.52%, 79.16%±4.31%, and 89.04%±4.68% in 21 days, respectively. The pure CS microspheres prepared in the presence of 10 mg of BSA burst release 39.53%±1.76% of BSA on the 1st day and cumulatively released 83.57%±2.33% of the total encapsulated BSA in 21 days. The SF-CS composite microspheres exhibited higher sustained release than did the pure CS microspheres, and thus these composite microspheres might function as a superior drug carrier.

[An observation of repair of burn wound with consanguineous skin pretreated with Tripterygium wilfordii].

OBJECTIVE: To explore new source of skin for burn wound coverage. METHODS: Split-thickness consanguineous skin was harvested from New Zealand white rabbit and was soaked in 200 g/L of multi-peptides of Tripterygium wilfordii, 50 g/L of dexamethasonel, on 9 g/L of normal saline solution for 15 - 30 mins, respectively. The consanguineous skin was thereafter grafted onto the whole layer skin defects in filial generation of rabbits with non-consanguineous skin as the control. The survival time and rejection of the grafted skin was observed. RESULTS: The rejection appeared evidently less intense and survived significantly longer (43 +/- 3.5 days) when the consanguineous skin was pretreated by Tripterygium wilfordii. However the grafted consanguineous skin survived for 30 +/- 2.5 days when it was pretreated by dexamethasone. The grafted skin was quickly rejected and survived only for 11 +/- 1.6 days when the skin was pretreated by normal saline or the skin was non-consanguineous. CONCLUSION: Consanguineous skin possessed partial compatibility with the recipient due to similar antigen, which was beneficial to the its survival, especially after the skin was pretreated.