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The β2-adrenergic receptor (β2AR) is a G-protein-coupled receptor (GPCR) that responds to the hormone adrenaline and is an important drug target in the context of respiratory diseases, including asthma. β2AR function can be regulated by post-translational modifications such as phosphorylation and ubiquitination at the C-terminus, but access to the full-length β2AR with well-defined and homogeneous modification patterns critical for biochemical and biophysical studies remains challenging. Here, we report a practical synthesis of differentially modified, full-length β2AR based on a combined native chemical ligation (NCL) and sortase ligation strategy. An array of homogeneous samples of full-length β2ARs with distinct modification patterns, including a full-length β2AR bearing both monoubiquitination and octaphosphorylation modifications, were successfully prepared for the first time. Using these homogeneously modified full-length β2AR receptors, we found that different phosphorylation patterns mediate different interactions with β-arrestin1 as reflected in different agonist binding affinities. Our experiments also indicated that ubiquitination can further modulate interactions between β2AR and β-arrestin1. Access to full-length β2AR with well-defined and homogeneous modification patterns at the C-terminus opens a door to further in-depth mechanistic studies into the structure and dynamics of β2AR complexes with downstream transducer proteins, including G proteins, arrestins, and GPCR kinases.

Blockade of the interaction of anaphylatoxin C5a with its receptor C5aR1 has been actively studied as a potential treatment for many inflammatory diseases; but current C5a antagonists exhibit inadequate potency and poor species cross-reactivity, and novel biochemical tools are needed to investigate whether the core region of C5a contains important interaction epitopes that can explain these limitations. Herein, we report the development of chimeric protein C5a probes containing both the complete core region of rat or human C5a, and the small-molecule antagonist PMX53-1. These probes were chemically synthesized through hydrazide-based native chemical ligation of a linear peptide hydrazide with the requisite cyclopeptidic antagonist, both of which were made by solid-phase synthesis. Quasi-racemic X-ray crystallography established that attachment of PMX53-1 did not affect the structure of the core region of C5a. Subsequent C5aR1 activity assays demonstrated the probes can provide valuable insights into the development of C5a antagonists; for example, they exhibited significantly better binding affinity and much improved species cross-reactivity than PMX53-1, supporting the notion that the effect of some epitopes outside the C-terminus of C5a should be taken into consideration when designing better C5a antagonists. Surprisingly, the core region of C5a was found to partially agonize C5aR1, suggesting the presence of more than one agonistic interaction in the binding of C5a to C5aR1. This study exemplifies the value of chemical protein synthesis in developing novel receptor probes for drug discovery research.

Photon bunching, a feature of classical thermal fields, has been widely exploited to implement ghost imaging. Here we show that spatial photon antibunching can be experimentally observed via low-pass filtering of the intensities of the two thermal light beams from a beamsplitter correlation system. Through suitable choice of the filter thresholds, the minimum of the measured normalized anti-correlation function, i.e., antibunching dip, can be lower than 0.2, while its full-width-at-half-maximum can be much narrower than that of the corresponding positive correlation peak. Based on this anti-correlation effect, a super-resolution negative ghost image is achieved in a lensless scheme, in which the spatial resolution can exceed the Rayleigh diffraction limit by more than a factor of two. The setup is quite simple and easy to implement, which is an advantage for practical applications.

We have described the chemical synthesis of d-Sortase A in large quantity and high purity by a hydrazide ligation strategy. The d-Sortase was fully active toward d-peptides and D/L hybrid proteins, and the ligation efficiency was unaffected by the chirality of the C-terminus substrate. This study points toward using d-sortase ligation as a modern ligation method for d-proteins and D/L hybrid proteins and expands the chemical protein synthesis toolbox in biotechnology.

Speech endpoint detection plays an important role in speech signal processing. In this paper, a method of speech endpoint detection based on empirical mode decomposition is introduced for accurately detecting the speech endpoint. This method used in speech signal decomposition gets a set of intrinsic mode functions (IMF). An IMF which contained a lot of noise must be filtered, and the rest of IMFs can be reconstructed to a new speech signal. The speech endpoint is detected by average magnitude difference function precisely. Simulation experiments show that the method proposed in this paper can eliminate the impact of noise effectively and detect the speech signal endpoint accurately.

Feature extraction is the key to the object recognition. How to obtain effective, reliable characteristic parameters from the limited measured data is a question of great importance in feature extraction. This paper presents a method based on Empirical Mode Decomposition (EMD) for the extraction of Mel Frequency Cepstrum Coefficients (MFCCs) and its first order difference from original speech signals that contain four kinds of emotions such as anger, happiness, surprise and natural for emotion recognition. And the experiments compare the recognition rate of MFCC, differential MFCC (Both of them are extracted based on EMD) or their combination through using Support Vector Machine (SVM) to recognize speakers' emotional speech identity. It proves that the combination of MFCC and its first order difference has a highest recognition rate.

This research aims at investigating the response characteristics of fiber Bragg grating sensors (FBGs) to ultrasonic signals. The testing system was set up with a tunable laser source and the FBGs installed on the surface of an aluminum plate. Then the response characteristics of FBGs were compared, in condition of putting the ultrasonic driving source in the different longitudinal, lateral and angular separation. Measurements were taken by changing the distance between the sensor and the transducer from 60 mm to 200 mm with a step of 20 mm. Then keeping the distance at 100 mm and 200 mm respectively, do the angular experiment with the angle from 0° to 90° by the step of 10°. Experiment results show that FBG can get better signals when the transducer is along its axial direction. When the location of the transducer is changed linearly, no obvious linear change of the signal strength has been found.

Disulfide-rich proteins are useful as drugs or tool molecules in biomedical studies, but their synthesis is complicated by the difficulties associated with their folding. Here, we describe a removable glycosylation modification (RGM) strategy that expedites the chemical synthesis of correctly folded proteins with multiple or even interchain disulfide bonds. Our strategy comprises the introduction of simple O-linked β-N-acetylglucosamine (O-GlcNAc) groups at the Ser/Thr sites that effectively improve the folding of disulfide-rich proteins by stabilization of their folding intermediates. After folding, the O-GlcNAc groups can be efficiently removed using O-GlcNAcase (OGA) to afford the correctly folded proteins. Using this strategy, we completed the synthesis of correctly folded hepcidin, an iron-regulating hormone bearing four pairs of disulfide-bonds, and the first total synthesis of correctly folded interleukin-5 (IL-5), a 26 kDa homodimer cytokine responsible for eosinophil growth and differentiation.

ZnO nanoparticles were carried out by Microemulsion method in the presence of TritonX-100 (poly oxyethylene tert-octylphenyl ether) as a surfactant. X-100/n-hextnol/cyclohexane/ waterW/O microemulsion system was also determined. Zinc chloride (ZnCl2·2H2O) and ammonia (NH3·H2O) were used as raw materials. The results indicated that the formation of ZnO nanoparticles was confirmed, using X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The results showed that the nanoparticle was exactly ZnO with wurtzite type crystalline structure and the size of nanoparticles is strongly affected by the ratio of water to surfactant(R). With the R value increase, the particles size became larger.

A highly sensitive and simple method was developed for the simultaneous determination of trace cadmium and mercury in tobacco samples by cold vapor generation-atomic fluorescence spectrometry equipped with an intermittent flow reactor. The reaction was accomplished with potassium tetrahydroborateiii in aqueous solutions. A newly modified atomizer was presented on the basis of the present atomic fluorescence system, which effectively improved the stability of the signals. Special accent was put on the study of the conditions for the generation of volatile cadmium and mercury species were investigated in detail. Some transition metal ions that could be used as sensitivity enhancers, including ironiii, cobaltii, nickelii, zincii and molybdenumvi in the presence of thiourea. The tolerance to the interference of coexisting ions was carefully examined in this system. Under optimal conditions, the detection limits 3σ were evaluated to be 2.8 ng l−1for cadmium and 4.3 ng l−1for mercury, respectively. The relative standard deviations for 10 replicate determinations of 0.8 µg l−1mercury and 1 µg l−1cadmium were 3.2 and 2.9, respectively. The proposed method was successfully applied to the simultaneous determination of mercury and cadmium in tobacco leaf samples.

A highly sensitive and simple method was developed for the simultaneous determination of trace cadmium and mercury in tobacco samples by cold vapor generation-atomic fluorescence spectrometry equipped with an intermittent flow reactor. The reaction was accomplished with potassium tetrahydroborate(iii) in aqueous solutions. A newly modified atomizer was presented on the basis of the present atomic fluorescence system, which effectively improved the stability of the signals. Special accent was put on the study of the conditions for the generation of volatile cadmium and mercury species were investigated in detail. Some transition metal ions that could be used as sensitivity enhancers, including iron(iii), cobalt(ii), nickel(ii), zinc(ii) and molybdenum(vi) in the presence of thiourea. The tolerance to the interference of coexisting ions was carefully examined in this system. Under optimal conditions, the detection limits (3σ) were evaluated to be 2.8 ng l−1 for cadmium and 4.3 ng l−1 for mercury, respectively. The relative standard deviations for 10 replicate determinations of 0.8 µg l−1 mercury and 1 µg l−1 cadmium were 3.2% and 2.9%, respectively. The proposed method was successfully applied to the simultaneous determination of mercury and cadmium in tobacco leaf samples.