Mechanism of Klebsiella pneumoniae resistance to carbapenem antibiotics

Purpose: To investigate the mechanism of action of Klebsiella pneumoniae (Kpn) resistance to carbapenem. Methods: The susceptibility of six Klebsiella pneumoniae strains to antibiotics was determined using KB assay. Six isolated strains which were resistant to carbapenem were identified and collected using modified Hodge test. The phenotypes of metal enzyme were evaluated by ethylene diamine tetraacetic acid (EDTA) disk diffusion method. The genes for beta-lactamases, including KPC gene, were examined. Results: The six carbapenem-resistant strains of Klebsiella pneumoniae were resistant to imipenem, meropenem and aztreonam, but were sensitive to amikacin, fosfomycin, minocycline, and polymyxin. The six pathogens did not produce metal enzyme, but they produced carbapenemases. Moreover, the six strains partially carried blaTEM or blaSHV gene, but all had blaKPC-2 gene. Conclusion: These results suggest that the pathogens that contain blaKPC-2 gene may be involved in the mechanism of Klebsiella pneumoniae (Kpn) resistance to carbapenem

Knowledge atlas of antibody-drug conjugates on CiteSpace and clinical trial visualization analysis

ObjectiveAntibody-drugs conjugates (ADCs) are novel drugs with highly targeted and tumor-killing abilities and developing rapidly. This study aimed to evaluate drug discovery and clinical trials of and explore the hotspots and frontiers from 2012 to 2022 using bibliometric methods.MethodsPublications on ADCs were retrieved between 2012 and 2022 from Web of Science (WoS) and analyzed with CiteSpace 6.1.R2 software for the time, region, journals, institutions, etc. Clinical trials were downloaded from clinical trial.org and visualized with Excel software.ResultsA total of 696 publications were obtained and 187 drug trials were retrieved. Since 2012, research on ADCs has increased year by year. Since 2020, ADC-related research has increased dramatically, with the number of relevant annual publications exceeding 100 for the first time. The United States is the most authoritative and superior country and region in the field of ADCs. The University of Texas MD Anderson Cancer Center is the most authoritative institution in this field. Research on ADCs includes two clinical trials and one review, which are the most influential references. Clinical trials of ADCs are currently focused on phase I and phase II. Comprehensive statistics and analysis of the published literature and clinical trials in the field of ADCs, have shown that the most studied drug is brentuximab vedotin (BV), the most popular target is human epidermal growth factor receptor 2 (HER2), and breast cancer may become the main trend and hotspot for ADCs indications in recent years.ConclusionAntibody-drug conjugates have become the focus of targeted therapies in the field of oncology. The innovation of technology and combination application strategy will become the main trend and hotspots in the future

Image coding with wavelet transform and different quantization techniques

In this thesis, some hybrid SPIHT algorithms have been proposed to improve the performance of original SPIHT algorithm for both noiseless channel and noisy channel.Master of Engineerin

Highly scalable 2D model-based video coding

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Highly scalable 2D model-based video coding.

With rapid mergers of computer, communications, and entertainment industries, we can expect a trend of growing heterogeneity (in channel bandwidth, receiver capacity, etc.) for future digital video coding applications. Furthermore, some new functions appear, such as object manipulation, which should be supported by the video coding techniques. The traditional video coding approach is very constrained and inefficient to the heterogeneity issue and user interaction. Scalable coding, allowing partial decoding at a variety of resolution, temporal, quality, and object levels from a single compressed codestream, is widely considered as a promising technology for efficient signal representation and transmission in a heterogeneous environment. However, although several scalable algorithms have been proposed in the literature and the international standards over the last decade, further research is necessary to improve the compression performance of scalable video coding. This thesis investigates scalable 2D model-based video coding method with efficient video compression as well as excellent scalability performance, in order to satisfy the newly appeared requirements. It first examines main model-based video coding techniques and scalable video coding methods. Also, the parametric video models that describe the real world and image generation process are briefly described. Next, video segmentation algorithms are investigated to semantically represent the video frame into video objects. At the first frame, the texture information and the motion from first several frames are used to extract the semantic foreground objects. For some sequences, user interaction is required to get semantic objects. In later frames, the proposed complexity-scalable contour-tracking algorithm is used to segment each frame. After that, each object is progressively approximated using three-layer 2D mesh model. In order to represent the motion of human face more precisely, face detection and modelling are also investigated. This technique, in which human face is modelled separately, is shown to produce improvements of object motion representation. Scalable model compression is also outlined in this thesis. Object model is represented into two parts: object shape and interior object model, which are compressed separately. A scalable contour approximation algorithm is proposed. Both intra- and predictive scalable shape-coding algorithms are investigated and proposed to code the object shape progressively. The encoded coarser layers are used to improve the coding efficiency of the current layer. The effectiveness of these algorithms is demonstrated through the results of extensive experiments. We also investigate the scalable texture coding of video objects. An improved shape-adaptive SPECK algorithm is employed in intra-texture coding and is also used for residual texture coding after motion compensated temporal filtering. During motion compensated temporal filtering, scalable mesh object model is used, and scalable motion vector coding is achieved using CABAC codec. A hierarchically structured bitstream is created, which is optimised for rate-distortion, to facilitate efficient bit truncation and bit allocation among video frames and video objects. The coding system can encode/decode the video object independently and generate a separate bit stream for each object. As is exhibited in our experiments, such a high coding scalability in the proposed coding system is achieved without a significant cost in compression performance commonly experienced in most scalable coding systems

Homogeneous Gold Redox Chemistry: Organometallics, Catalysis, and Beyond

Gold redox chemistry holds the promise of unique reactivities and selectivities that are different to other transition metals. Recent studies have utilized strain release, ligand design, and photochemistry to promote the otherwise sluggish oxidative addition to Au(I) complexes. More details on the reductive elimination from Au(III) complexes have also been revealed. These discoveries have facilitated the development of gold redox catalysis and will continue to offer mechanistic insight and inspiration for other transition metals. This review highlights how research in organometallic chemistry has led to gold redox catalysis, as well as applications in materials science, bioconjugation, and radiochemical synthesis

Copper-Mediated Trifluoromethylation of α‑Diazo Esters with TMSCF₃: The Important Role of Water as a Promoter

Copper-mediated trifluoromethylation of α-diazo esters with TMSCF₃ reagent has been developed as a new method to prepare α-trifluoromethyl esters. This trifluoromethylation reaction represents the first example of fluoroalkylation of a non-fluorinated carbene precursor. Water plays an important role in promoting the reaction by activating the “CuCF₃” species prepared from CuI/TMSCF₃/CsF (1.0:1.1:1.1). The scope of this trifluoro­methyl­ation reaction is broad, and its efficiency is demonstrated in the synthesis of a variety of aryl-, benzyl-, and alkyl-substituted 3,3,3-trifluoro­propano­ates