The presence of petroleum acids in crude oils is a key problem in refineries due to corrosion to industrial units. To economically and effectively remove the petroleum acids from high acid crude oils is an urgent project. A theoretical and experimental study to develop a catalytic decarboxylation process to remove petroleum acids from high acid crude oils was conducted. By using the molecular simulation technology, a solid acid catalyst was constructed for removing petroleum acids. The experimental results indicated that the acid removal rate of a high acid crude oil with a total acid number (TAN) of 12.52 over the solid acid catalyst of MLC500 was up to 97% at a volume space velocity of 8 h−1, ratio of catalyst to oil of 7.5, and temperature of 460 °C in the fixed fluid bed reactor.
Detection of viruses with high sensitivity is critical
for the
prevention and treatment of the related disease. Two homogeneous target-induced
cascade amplification methods were proposed for the detection of enterovirus
71 and coxsackievirus B3. These methods both employ DNAzyme but differ
in the way in which the DNAzyme is amplified. In the hybridization
chain reaction (HCR)-based strategy, the DNAzyme is assembled by hairpin
DNA strands, while in the rolling circle amplification (RCA)-based
strategy, the DNAzyme is synthesized by the polymerase. On the basis
of the virion structure, we investigated the effects of using only
VP1-antibody or VP1-antibody and VP2-antibody on the detection. And
the combination of two kinds of antibodies was found to further improve
the performance of the detection. Subsequently, the simultaneous detection
of EV71 and CVB3 was achieved by the RCA-based strategy. And the proposed
methods were also applied in clinical samples analysis with a satisfactory
result, showing great potential for applications in virus detection.
When
dealing with infectious pathogens, the risk of contamination
or infection in the process of detecting them is nonnegligible. Separation-free
detection will be beneficial in operation and safety. In this work,
we proposed a DNAzyme walker for homogeneous and isothermal detection
of enterovirus. The DNAzyme is divided into two inactivate subunits.
When the subunit-conjugated antibody binds to the target virus, the
activity of the DNAzyme recovers as a result of spatial proximity.
The walker propels, and the fluorescence recovers. The final fluorescence
intensity of the reaction mixture is related to the concentration
of the target virus. The detection limit of this proposed method is
6.6 × 104 copies/mL for EV71 and 4.3 × 104 copies/mL for CVB3, respectively. Besides, this method was
applied in detection of EV71 in clinical samples with a satisfactory
result. The entire experiment is easy to operate, and the proposed
method has great potential for practical use.
HIV nucleic acids, one kind of significant biomarker, play an important role in fundamental studies and clinical diagnosis. Importantly, the early accurate diagnosis for HIV nucleic acids at ultralow concentrations can potentially extend the life of patients. In the current work, we developed a DNA nanomachine on gold nanoparticles (AuNPs) coupling rolling circle amplification and DNA walker cascade amplification for ultrasensitive detection of HIV nucleic acids. This DNA nanomachine sensing strategy exhibits a significantly low detection limit down to 1.46 fM. Furthermore, this DNA nanomachine biosensor is capable of detecting target DNA in real samples because of its high selectivity and sensitivity. Moreover, the DNA nanomachine biosensor is capable of discriminating single-base mismatch lower than 3.5 pM. The results showed that this DNA nanomachine biosensor has the potential for biomedical studies and clinical applications.
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