Microbial flocculant produced by a novel sp., strain A9, using food processing wastewater to replace fermentation medium and its application for the removal of Pb(II) from aqueous solution

Due to high production costs, the popularization and application of microbial flocculants in the field of water treatment have been limited. In this study, the capture of lead ions by the fermentation broth of a novel Paenibacillus sp. strain A9 and cultured with food wastewater was further investigated. The results revealed that the production of MBFA9 could be increased significantly by adding a small amount of carbon and nitrogen to food wastewater. Under the best experimental conditions (pH 8.5, culture temperature 30°C, 150 r/min), adding 1% (m/v) carbon and 0.1% (m/v) nitrogen to 1% (v/v) wastewater resulted in a yield of MBFA9 of 6.29 g/l. At a temperature of 30°C, pH of 5, contact time of 35 min, and FBA9 dosage of 5%, the removal rate and removal capacity of Pb(II) reached the highest values of 95.1% and 317 mg/g, respectively. Field emission scanning electron microscopy analysis indicated that bacterial cells, metabolite small molecule acids, and MBFA9 in FBA9 all contributed to the removal of Pb(II). Fourier-transform infrared spectrometry analysis indicated that functional groups such as –OH, –COOH, –CO, and –NH 2 existed in MBFA9 and on the cell surface. Various mechanisms involved in Pb(II) removal can occur simultaneously, including cell surface adsorption, microcrystallization, and biological flocculation

Application of a new type of Si–Al porous clay material as a solid phase support for immobilizing sp. PM3 to treat domestic sewage

A novel Si–Al porous clay material W (reprocessed from ceramic waste) was used for Acidovorax sp. strain PM3 immobilization to promote the growth of strains and improve nitrogen and phosphorus removal performance in water treatment systems. The porous clay material W was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy indicating that porous clay material W was a type of mullite with 63.52 m 2 /g specific surface area. After immobilization, the maximum biomass increased 2.7 times the specific growth rate and the removal rates of chemical oxygen demand (COD), ammonia (NH 4 + –N), and total phosphorus (TP) by the immobilized PM3 were 42.99, 29.19, and 11.76% higher than the free strain after 24 h. The Monod equation showed that the growth rate and processing speed of immobilized PM3 increased. The maximum adsorption capacities of COD and NH 4 + –N onto porous clay material W were 2.33 and 0.32 mg/g on the basis of Langmuir isotherm. The removal capacities of COD, NH 4 + –N, and TP by the immobilized PM3 were 588.24, 20.37, and 5.06 mg/l, respectively, as shown by kinetic studies. These results demonstrated that porous clay material W could improve the efficiency of microbial nitrogen and phosphorus removal, and the immobilized microorganism system could effectively treat domestic sewage. The adsorption isotherms can well describe the adsorption process. The maximum adsorption capacity of COD and NH 4 + –N on porous clay material W is 2.33 and 0.32 mg/g, respectively. Kinetic studies showed that the removal capacity of immobilized PM3 to COD, NH 4 + –N, and TP was 58.824, 20.37, and 5.06 mg/l, respectively

Optimizing the Passenger Air Bag of an Adaptive Restraint System for Multiple Size Occupants

<div><p><b>Objective:</b> The development of the adaptive occupant restraint system (AORS) has led to an innovative way to optimize such systems for multiple size occupants. An AORS consists of multiple units such as adaptive air bags, seat belts, etc. During a collision, as a supplemental protective device, air bags can provide constraint force and play a role in dissipating the crash energy of the occupants’ head and thorax. This article presents an investigation into an adaptive passenger air bag (PAB).</p><p><b>Methods:</b> The purpose of this study is to develop a base shape of a PAB for different size occupants using an optimization method. Four typical base shapes of a PAB were designed based on geometric data on the passenger side. Then 4 PAB finite element (FE) models and a validated sled with different size dummy models were developed in MADYMO (TNO, Rijswijk, The Netherlands) to conduct the optimization to obtain the best baseline PAB that would be used in the AORS. The objective functions—that is, the minimum total probability of injuries (∑<i>P</i>_comb) of the 5th percentile female and 50th and 95th percentile male dummies—were adopted to evaluate the optimal configurations. The injury probability (<i>P</i>_comb) for each dummy was adopted from the U.S. New Car Assessment Program (US-NCAP).</p><p><b>Results:</b> The parameters of the AORS were first optimized for different types of PAB base shapes in a frontal impact. Then, contact time duration and force between the PAB and dummy head/chest were optimized by adjusting the parameters of the PAB, such as the number and position of tethers, lower the <i>P</i>_comb of the 95th percentile male dummy.</p><p><b>Conclusions:</b> According to the optimization results, 4 typical PABs could provide effective protection to 5th and 50th percentile dummies. However, due to the heavy and large torsos of the 95th percentile occupants, the current occupant restraint system does not demonstrate satisfactory protective function, particularly for the thorax.</p></div

A re-examination of the current design rule for staggered bolted connections

This paper summarised and re-examined the theoretical basis of the commonly used design rule developed by Cochrane in the 1920s to consider staggered bolt holes in tension members, i.e., the s2/4g rule. The rule was derived assuming that the term two times the bolt hole diameter (2d0) in Cochrane’s original equation could be neglected, and assuming a value of 0.5 for the fractional deduction of a staggered hole in assessing the net section area. Although the s2/4g rule generally provides good predictions of the staggered net section area, the above-mentioned assumptions used in developing the rule are doubtful, in particular for a connection with a small gauge-to-bolt-hole diameter (g/d0) ratio. It was found that the omission of 2d0 in Cochrane’s original equation appreciably overestimates the net section area of a staggered bolted connection with a small g/d0 ratio. However, the assumed value of 0.5 for the fractional deduction of a staggered hole underestimates the staggered net section area for small g/d0 ratios. To improve the applicability of the above two assumptions, a modified design equation, which covers a full range of g/d0 ratio, was proposed to accurately predict the staggered net section area and was validated by the existing test data from the literature and numerical data derived from this study. Finally, a reliability analysis of the test and numerical data was conducted, and the results showed that the reliability of the modified design equation for evaluating the net section resistance of staggered bolted connections can be achieved with the partial factor of 1.25.</p

The effect of microflocculant MBFA9 and the mechanism of Pb(II) and Zn(II) removal from an aqueous solution

The removal mechanism of a microbial flocculant produced using a novel Paenibacillus sp. strain A9 (MBFA9) for two heavy metal ions, lead and zinc, from an aqueous solution is studied and compared. The removal rate of Pb(II) or Zn(II) by MBFA9 increased with an increase in the pH when the pH was less than 6.0. The removal rates were 91.26% for Pb(II) and 76.28% for Zn(II). The optimum condition was found at a pH of 5.5 and dosage of MBFA9 of 5% (v/v, 150 mg/L). When the initial concentration of metal ions was 100 mg/L, the removal capacity was 453.70 mg/g for Pb(II) and 398.48 mg/g for Zn(II). The capture process of a single metal ion of Pb(II) or Zn(II) by MBFA9 agreed with the Langmuir adsorption model with fitting coefficients of 0.9907 and 0.9408, respectively. Both the adsorption kinetics and adsorption equilibrium, usually described as adsorption isotherms, showed that this process of Pb(II) or Zn(II) capture by MBFA9 involved simple adsorption of a single molecular layer. The maximum reaction rate constant, K 2 , of MBFA9 in the captured Pb(II) decreased from 0.0497 to 0.0095, with an increase in the Zn(II) concentration under different Zn(II) concentrations (0, 20, and 40 mg/L). This indicated that the presence of Zn(II) competed with PB(II) for the binding sites of MBFA9 and led to a decrease in the removal rate. The process was controlled by chemical adsorption

Microstructure and mechanical properties of squeeze-cast Al-5.0Cu-1Mn-based alloys with different Ni content

In this study, the effects of Ni content on the microstructure and mechanical properties of Al-5.0Cu-1Mn-based alloys were investigated. The results demonstrate that Ni alloying refines the grain size and enhances castability. At low Ni content, some of Ni atoms participate in forming Al7Cu4Ni at the grain boundaries. The rest Ni segregates to the interface between α-Al and AlCu3Mn2 phase, which inhibits AlCu3Mn2 growth. The amount of Ni-rich phase at grain boundaries increases significantly as Ni concentration increases at the expense of the decline precipitates. After T6 treatment, the lamellar Ni-rich phase spheroidized into discrete particles that were uniformly distributed along the grain boundaries. Ni-rich phase of particles can effectively pin grain boundaries and prevent grain rotation. The optimum mechanical property is achieved with 1% Ni addition, predominantly due to the synergistic strengthening of eutectic strengthening and precipitation strengthening. The ultimate tensile strength, yield strength and elongation reach 505 MPa, 348 MPa and 16.5% respectively, which far exceed the current commercial cast aluminium alloys. With increasing Ni concentration, the fracture mode of the alloy changes from ductile fracture to brittle-ductile mixed fracture, because the high amount of Ni-rich phase intermetallic compounds increase the sites for localized brittle fractures

Crushing behavior of SKYDEX(R) material

SKYDEX &#0174; material is an advanced lightweight porous medium consisting of layers of periodic twin-hemispherical microstructures made of thermoplastic polyurethane. This material is used widely in personnel and structural protection. This paper reports a combined experimental and numerical study on crushing behavior of such material. Compression tests were conducted on the SKYDEX &#0174;panels at the strain rates of 0.01&#8764;10 s-1. A 3D finite element model was developed and validated against experimental data. Based on the FE model, the deformation mode of the microstructures, strength, energy absorption, as well as strain rate effect were predicted and analyzed. Additional simulations were conducted to establish the relationship between the peak strength coefficient and relative density. SKYDEX&#0174; material has been found to be a competitive energy absorber among cellular solids

MiR-324-5p Suppresses Hepatocellular Carcinoma Cell Invasion by Counteracting ECM Degradation through Post-Transcriptionally Downregulating ETS1 and SP1.

Hepatocellular carcinoma (HCC) is one of the common malignancies, which is highly metastatic and the third common cause of cancer deaths in the world. The invasion and metastasis of cancer cells is a multistep and complex process which is mainly initiated by extracellular matrix (ECM) degradation. Aberrant expression of microRNA has been investigated in HCC and shown to play essential roles during HCC progression. In the present study, we found that microRNA-324-5p (miR-324-5p) was downregulated in both HCC cell lines and tissues. Ectopic miR-324-5p led to the reduction of HCC cells invasive and metastatic capacity, whereas inhibition of miR-324-5p promoted the invasion of HCC cells. Matrix metalloproteinase 2 (MMP2) and MMP9, the major regulators of ECM degradation, were found to be downregulated by ectopic miR-324-5p, while upregulated by miR-324-5p inhibitor. E26 transformation-specific 1 (ETS1) and Specificity protein 1 (SP1), both of which could modulate MMP2 and MMP9 expression and activity, were presented as the direct targets of and downregulated by miR-324-5p. Downregulation of ETS1 and SP1 mediated the inhibitory function of miR-324-5p on HCC migration and invasion. Our study demonstrates that miR-324-5p suppresses hepatocellular carcinoma cell invasion and might provide new clues to invasive HCC therapy