Utility of Triethyloxonium Tetrafluoroborate for Chloride Removal during Sarcosine N-Carboxyanhydride Synthesis: Improving NCA Purity.

The clinical translation of polysarcosine (pSar) as polyethylene glycol (PEG) replacement in the development of novel nanomedicines creates a broad demand of polymeric material in high-quality making high-purity sarcosine N-carboxyanhydride (Sar-NCA) as monomer for its production inevitable. Within this report, we present the use of triethyloxonium tetrafluoroborate in Sar-NCA synthesis with focus on amino acid and chloride impurities to avoid the sublimation of Sar-NCAs. With a view towards upscaling into kilogram or ton scale, a new methodology of monomer purification is introduced by utilizing the Meerwein's Salt triethyloxonium tetrafluoroborate to remove chloride impurities by covalent binding and converting chloride ions into volatile products within a single step. The novel straightforward technique enables access to monomers with significantly reduced chloride content (<100 ppm) compared to Sar-NCA derived by synthesis or sublimation. The derived monomers enable the controlled-living polymerization in DMF and provide access to pSar polymers with Poisson-like molecular weight distribution within a high range of chain lengths (Xn 25-200). In conclusion, the reported method can be easily applied to Sar-NCA synthesis or purification of commercially available pSar-NCAs and eases access to well-defined hetero-telechelic pSar polymers.

Investigating important and necessary conditions to analyse traffic noise levels at intersections in mid-sized cities.

Traffic noise is a major problem for urban residents, especially near intersections. In order to effectively manage and control traffic noise, there is a need for a better understanding of noise-influencing variables at intersections. In this way, the study aims to identify and distinguish the important and necessary conditions corresponding to the particular traffic noise level. Using 342 h of field data from 19 intersections in Kanpur, the current research has used the Partial Least Square-Structural Equation Modelling (PLS-SEM) and Necessary Condition Analysis (NCA). The study determines that traffic volume, honking, speed, and median width are important factors. Traffic volume and honking are positively affecting traffic noise level, while speed and median width have a negative effect. Further investigation reveals that only traffic volume and honking are necessary to achieve a particular traffic noise level. Policymakers can use these findings to manage and control traffic noise at intersections.

Pathways to improve energy efficiency under carbon emission constraints in iron and steel industry: Using EBM, NCA and QCA approaches.

Improving environmental performance of energy- and carbon-intensive sectors represented by the iron and steel (IS) industry is of utmost importance to address the challenges of resource depletion and climate change worldwide. This article adopts a global-super-Epsilon-Based Measure (EBM) model with undesirable output for IS energy efficiency estimation, identifies efficiency determinants based on Technology-Organization-Environment (TOE) framework, and analyzes various pathways for efficiency improvement by grouping Necessary Condition Analysis (NCA) and fuzzy-set Qualitative Comparative Analysis (fsQCA). Empirical testing using statistical data of the G20 economies during 2010-2020 demonstrates that: 1) energy efficiency in the IS industry in G20 countries has risen amidst fluctuations, with developed countries performing more efficiently than developing countries; 2) individual factors do not constitute a compulsory condition to achieve high energy efficiency in the IS industry; 3) three different paths to achieve high energy performance are found, that is, technology-structure driven, regulation-economy-technology driven, and regulation-technology-production driven. Heterogenous policy recommendations for efficiency gains in the IS sector of different countries with divergent features are proposed accordingly.

An extended version of Necessary Condition Analysis (NCA) allows more specific conclusions: an example involving well-being and resilience.

BACKGROUND: After conducting necessary condition analysis (NCA), researchers have concluded that a certain, not too low, level of well-being is necessary but not sufficient for a high level of resilience. However, as acknowledged by the developers of the test, NCA only evaluates if the association between two variables is characterized by some unspecified type of non-randomness and not conditions of necessity. METHOD: Earlier reported data on the association between well-being and resilience among Filipino adults (N = 533) in COVID-19 quarantine were re-analyzed with an extended version of NCA. RESULTS: Analyses indicated a significant necessity effect of resilience on overall well-being, which is not logically compatible with well-being being necessary but not sufficient for resilience. Analyses with an extended version of NCA suggested that the association between overall well-being and resilience was characterized by equal degrees of necessity and sufficiency. CONCLUSIONS: The original version of NCA is only capable of evaluating if the association between two variables is characterized by some unspecified type of non-randomness. The extended version of NCA allows researchers to draw more specific conclusions.

Racemic S-(ethylsulfonyl)-dl-cysteine N-Carboxyanhydrides Improve Chain Lengths and Monomer Conversion for ß-Sheet-Controlled Ring-Opening Polymerization.

The secondary structure formation of polypeptides not only governs folding and solution self-assembly but also affects the nucleophilic ring-opening polymerization of α-amino acid-N-carboxyanhydrides (NCAs). Whereby helical structures are known to enhance polymerization rates, ß-sheet-like assemblies reduce the propagation rate or may even terminate chain growth by precipitation or gelation. To overcome these unfavorable properties, racemic mixtures of NCAs can be applied. In this work, racemic S-(ethylsulfonyl)-dl-cysteine NCA is investigated for the synthesis of polypeptides, diblock and triblock copolypept(o)ides. In contrast to the polymerization of stereoregular S-(ethylsulfonyl)-l-cysteine NCA, the reaction of S-(ethylsulfonyl)-dl-cysteine NCA proceeds with a rate constant of up to kp  = 1.70 × 10-3 L mol-1 s -1 and is slightly faster than the enatiopure polymerization. While the polymerization of S-(ethylsulfonyl)-l-cysteine NCA suffers from incomplete monomer conversion and degrees of polymerization (DPs) limited to 30-40, racemic mixtures yield polypeptides with DPs of up to 102 with high conversion rates and well-defined dispersities (1.2-1.3). The controlled living nature of the ring-opening polymerization of S-(ethylsulfonyl)-dl-cysteine NCA thus enables the synthesis of triblock copolymers by sequential monomer addition. This methodology allows for precise control over DPs of individual blocks and yields uniform triblock copolymers with symmetric molecular weight distributions at a reduced synthetic effort.

Comparing Class-Aware and Pairwise Loss Functions for Deep Metric Learning in Wildlife Re-Identification.

Similarity learning using deep convolutional neural networks has been applied extensively in solving computer vision problems. This attraction is supported by its success in one-shot and zero-shot classification applications. The advances in similarity learning are essential for smaller datasets or datasets in which few class labels exist per class such as wildlife re-identification. Improving the performance of similarity learning models comes with developing new sampling techniques and designing loss functions better suited to training similarity in neural networks. However, the impact of these advances is tested on larger datasets, with limited attention given to smaller imbalanced datasets such as those found in unique wildlife re-identification. To this end, we test the advances in loss functions for similarity learning on several animal re-identification tasks. We add two new public datasets, Nyala and Lions, to the challenge of animal re-identification. Our results are state of the art on all public datasets tested except Pandas. The achieved Top-1 Recall is 94.8% on the Zebra dataset, 72.3% on the Nyala dataset, 79.7% on the Chimps dataset and, on the Tiger dataset, it is 88.9%. For the Lion dataset, we set a new benchmark at 94.8%. We find that the best performing loss function across all datasets is generally the triplet loss; however, there is only a marginal improvement compared to the performance achieved by Proxy-NCA models. We demonstrate that no single neural network architecture combined with a loss function is best suited for all datasets, although VGG-11 may be the most robust first choice. Our results highlight the need for broader experimentation and exploration of loss functions and neural network architecture for the more challenging task, over classical benchmarks, of wildlife re-identification.

Superfast and Water-Insensitive Polymerization on α-Amino Acid N-Carboxyanhydrides to Prepare Polypeptides Using Tetraalkylammonium Carboxylate as the Initiator.

We design the tetraalkylammonium carboxylate-initiated superfast polymerization on α-amino acid N-carboxyanhydrides (NCA) for efficient synthesis of polypeptides. Carboxylates, as a new class of initiator for NCA polymerization, can initiate the superfast NCA polymerization without the need of extra catalysts and the polymerization can be operated in open vessels at ambient condition without the use of glove box. Tetraalkylammonium carboxylate-initiated polymerization on NCA easily affords block copolymers with at least 15 blocks. Moreover, this method avoids tedious purification steps and enables direct polymerization on crude NCAs in aqueous environments to prepare polypeptides and one-pot synthesis of polypeptide nanoparticles. These advantages and the mild polymerization condition of tetraalkylammonium carboxylate-initiated NCA polymerization imply its great potential in functional exploration and application of polypeptides.

An unusual presentation of propylthiouracil-induced anti-MPO and PR3 positive ANCA vasculitis with associated anti-GBM antibodies, IgA nephropathy and an IgG4 interstitial infiltrate: a case report.

BACKGROUND: A number of disease processes can culminate in rapidly progressive glomerulonephritis, including pauci-immune focal segmental necrotising glomerulonephritis, usually seen with positive serum antineutrophil cytoplasmic antibodies (ANCA). Propylthiouracil (PTU) has been associated with drug-induced ANCA-associated vasculitis (AAV), with antibodies against myeloperoxidase (MPO) and proteinase 3 (PR3) present individually and together having been recognised. 'Double-positive' vasculitis with ANCA and anti-glomerular basement membrane (GBM) antibodies has also been reported in association with PTU treatment. We present a case of PTU-induced anti-MPO and PR3 positive ANCA vasculitis with associated anti-GBM antibodies, IgA nephropathy and an IgG4 interstitial infiltrate. CASE PRESENTATION: A 51-year-old man presented 2 weeks after re-commencing propylthiouracil (PTU) treatment for Graves' disease, with a severe acute kidney injury and haemato-proteinuria. He demonstrated positive titres for autoantibodies to PR3 (76.9 IU/mL), MPO (28.8 IU/mL) and GBM (94 IU/mL). Renal biopsy demonstrated numerous glomerular crescents, widespread IgG4-positive lymphoplasmacytic infiltrate and mesangial positivity for IgA. PTU was stopped and he was treated with steroids, plasma exchange and cyclophosphamide with sustained improvement in his renal function. CONCLUSIONS: This case of drug-induced AAV presented a unique and intriguing collection of serological and histological features. We propose that the PTU-induced AAV resulted in epiphenomena of anti-GBM antibody production and an IgG4-cell-rich tubulointerstitial infiltrate. It is uncertain whether the mesangial IgA deposition preceded or resulted from the AAV.

Evolving pediatric epidural practice: An institution's clinical experience over 20 years-A retrospective observational cohort study.

BACKGROUND AND OBJECTIVES: Epidural analgesia is an effective, established perioperative intervention in all age-groups. In children, however, epidural-related data are limited compared to the adult population. The aim of this study was to examine the use of pediatric epidural analgesia in our institution and, thereby, add to the existing data pool. METHODOLOGY: Patients who received epidural analgesia as part of their perioperative management between 1996 and 2016 at Great Ormond Street Hospital, London, UK, were studied to determine how epidural practice has changed over time, associated incidence of serious adverse events, complications, and patient/parent satisfaction. Epidural use and monitoring were in accordance with standard hospital protocols. Data were prospectively collected and entered into a secure database by trained personnel. These data were subsequently extracted for retrospective analysis. RESULTS: A total of 3876 patients were included. The median age was 4.4 years (range 1 day to 20 years), and the median weight was 20.3 kg. Across all age-groups, the lumbar region was the most common site of epidural insertion while urology (42.2%) and general surgery (37.3%) were the specialities for which it was most utilized. Over the study period, the number of epidurals performed declined while the number of surgical procedures performed simultaneously increased. The infusate most commonly used was local anesthetic with preservative-free morphine (71.9%). In 923 (23.2%) patients, systemic opioids were additionally used for analgesic management by means of patient-controlled analgesia or nurse-controlled analgesia. There was one serious adverse event in the form of permanent nerve injury, giving an overall incidence of approximately 1:3800. Other complications included postoperative nausea and vomiting (35.9%), urinary retention (4.4%), and pruritus (31%). Overall global satisfaction with the service was generally high, with 95% providing a rating of "very good" or "good." CONCLUSION: This study evaluated two decades of epidural practice in our institution. Epidural analgesia remains a safe, effective option for postoperative analgesia, but its use has declined over time, and this trend is likely to continue. Rates of serious adverse events and complications were low and comparable to those published in other similar studies. Global satisfaction among patients/parents remains high.

Clinical characteristics and outcomes of null-cell versus silent gonadotroph adenomas in a series of 1166 pituitary adenomas from a single institution.

OBJECTIVE: Nonfunctioning pituitary adenomas present without biochemical or clinical signs of hormone excess and are the second most common type of pituitary adenomas. The 2017 WHO classification scheme of pituitary adenomas differentiates null-cell adenomas (NCAs) and silent gonadotroph adenomas (SGAs). The present study sought to highlight the differences in patient characteristics and clinical outcomes between NCAs and SGAs. METHODS: The records of 1166 patients who underwent transsphenoidal surgery for pituitary adenoma between 2012 and 2019 at a single institution were retrospectively reviewed. Patient demographics and clinical outcomes were collected. RESULTS: Of the overall pituitary adenoma cohort, 12.8% (n = 149) were SGAs and 9.2% (n = 107) NCAs. NCAs were significantly more common in female patients than SGAs (61.7% vs 26.8%, p < 0.001). There were no differences in patient demographics, initial tumor size, or perioperative and short-term clinical outcomes. There was no significant difference in the amount of follow-up between patients with NCAs and those with SGAs (33.8 months vs 29.1 months, p = 0.237). Patients with NCAs had significantly higher recurrence (p = 0.021), adjuvant radiation therapy usage (p = 0.002), and postoperative diabetes insipidus (p = 0.028). NCA pathology was independently associated with tumor recurrence (HR 3.64, 95% CI 1.07-12.30; p = 0.038), as were cavernous sinus invasion (HR 3.97, 95% CI 1.04-15.14; p = 0.043) and anteroposterior dimension of the tumor (HR 2.23, 95% CI 1.09-4.59; p = 0.030). CONCLUSIONS: This study supports the definition of NCAs and SGAs as separate subgroups of nonfunctioning pituitary adenomas, and it highlights significant differences in long-term clinical outcomes, including tumor recurrence and the associated need for adjuvant radiation therapy, as well as postoperative diabetes insipidus. The authors also provide insight into independent risk factors for these outcomes in the adenoma population studied, providing clinicians with additional predictors of patient outcomes. Follow-up studies will hopefully uncover mechanisms of biological aggressiveness in NCAs and associated molecular targets.

Performance characteristics of the adjusted r2 algorithm for determining the start of the terminal disposition phase and comparison with a simple r2 algorithm and a visual inspection method.

The adjusted r2 algorithm is a popular automated method for selecting the start time of the terminal disposition phase (tz ) when conducting a noncompartmental pharmacokinetic data analysis. Using simulated data, the performance of the algorithm was assessed in relation to the ratio of the slopes of the preterminal and terminal disposition phases, the point of intercept of the terminal disposition phase with the preterminal disposition phase, the length of the terminal disposition phase captured in the concentration-time profile, the number of data points present in the terminal disposition phase, and the level of variability in concentration measurement. The adjusted r2 algorithm was unable to identify tz accurately when there were more than three data points present in a profile's terminal disposition phase. The terminal disposition phase rate constant (λz ) calculated based on the value of tz selected by the algorithm had a positive bias in all simulation data conditions. Tolerable levels of bias (median bias less than 5%) were achieved under conditions of low measurement variability. When measurement variability was high, tolerable levels of bias were attained only when the terminal phase time span was 4 multiples of t1/2 or longer. A comparison of the performance of the adjusted r2 algorithm, a simple r2 algorithm, and tz selection by visual inspection was conducted using a subset of the simulation data. In the comparison, the simple r2 algorithm performed as well as the adjusted r2 algorithm and the visual inspection method outperformed both algorithms. Recommendations concerning the use of the various tz selection methods are presented.

Criteria for reporting noncompartmental estimates of half-life and area under the curve extrapolated to infinity.

Various criteria have been proposed for determining the reliability of noncompartmental pharmacokinetic estimates of the terminal disposition phase half-life (t1/2 ) and the extrapolated area under the curve (AUCextrap ). This simulation study assessed the performance of two frequently used reportability rules: the terminal disposition phase regression adjusted-r2 classification rule and the regression data point time span classification rule. Using simulated data, these rules were assessed in relation to the magnitude of the variability in the terminal disposition phase slope, the length of the terminal disposition phase captured in the concentration-time profile (data span), the number of data points present in the terminal disposition phase, and the type and level of variability in concentration measurement. The accuracy of estimating t1/2 was satisfactory for data spans of 1.5 and longer, given low measurement variability; and for spans of 2.5 and longer, given high measurement variability. Satisfactory accuracy in estimating AUCextrap was only achieved with low measurement variability and spans of 2.5 and longer. Neither of the classification rules improved the identification of accurate t1/2 and AUCextrap estimates. Based on the findings of this study, a strategy is proposed for determining the reportability of estimates of t1/2 and area under the curve extrapolated to infinity.

Hybridization of TEDOR and NCX MAS solid-state NMR experiments for simultaneous acquisition of heteronuclear correlation spectra and distance measurements.

Magic angle spinning (MAS) solid-state NMR (ssNMR) spectroscopy is a major technique for the characterization of the structural dynamics of biopolymers at atomic resolution. However, the intrinsic low sensitivity of this technique poses significant limitations to its routine application in structural biology. Here we achieve substantial savings in experimental time using a new subclass of Polarization Optimized Experiments (POEs) that concatenate TEDOR and SPECIFIC-CP transfers into a single pulse sequence. Specifically, we designed new 2D and 3D experiments (2D TEDOR-NCX, 3D TEDOR-NCOCX, and 3D TEDOR-NCACX) to obtain distance measurements and heteronuclear chemical shift correlations for resonance assignments using only one experiment. We successfully tested these experiments on N-Acetyl-Val-Leu dipeptide, microcrystalline U-13C,15N ubiquitin, and single- and multi-span membrane proteins reconstituted in lipid membranes. These pulse sequences can be implemented on any ssNMR spectrometer equipped with standard solid-state hardware using only one receiver. Since these new POEs speed up data acquisition considerably, we anticipate their broad application to fibrillar, microcrystalline, and membrane-bound proteins.

Two NCA1 isoforms interact with catalase in a mutually exclusive manner to redundantly regulate its activity in rice.

BACKGROUND: NCA1 (NO CATALASE ACTIVITY 1) was recently identified in Arabidopsis as a chaperone protein to regulate catalase (CAT) activity through maintaining the folding of CAT. The gene exists mainly in higher plants; some plants, such as Arabidopsis, contain only one NCA1 gene, whereas some others such as rice harbor two copies. It is not yet understood whether and how both isoforms have functioned to regulate CAT activity in those two-copy-containing plant species. RESULTS: In this study, we first noticed that the spatiotemporal expression patterns of NCA1a and NCA1b were very similar in rice plants. Subsequent BiFC and yeast three-hybrid experiments demonstrated that both NCA1a and NCA1b show mutually exclusive, rather than simultaneous, interaction with CAT. For a further functional analysis, nca1a and nca1b single mutants or double mutants of rice were generated by CRISPR/Cas9. Analysis on these mutants under both normal and salinity stress conditions found that, as compared with WT, either nca1a or nca1b single mutant showed no difference at phenotypes and CAT activities, whereas the double mutants constantly displayed very low CAT activity (about 5%) and serious lesion phenotypes. CONCLUSIONS: These results suggest that NCA1a and NCA1b show mutually exclusive interaction with CAT to regulate CAT activity in a functionally-redundant manner in rice.

Loss of whole chromosome X predicts prognosis of neuroblastoma patients with numerical genomic profile.

BACKGROUND: Neuroblastoma (NB), a pediatric tumor of the sympathetic nervous system, is characterized by very frequent chromosomal aberrations at the onset of the disease. Identification of further risk factors for relapse, which could lead to increased survival and potentially reduced late effects among survivors, is still urgently needed. Segmental chromosome aberrations (SCA) are associated with poor prognosis, whereas numerical whole-chromosome aberrations (NCA) are found in patients with a good prognosis; however, a small percentage of the latter patients (10%-15%) subsequently relapse and/or die of disease. PROCEDURE: DNA copy-number data from 174 NB patients with an NCA genomic profile were analyzed. Association between NCA and event-free survival (EFS) was investigated by the Kaplan-Meier estimator and prognostic decision tree (DT). RESULTS: DT identified 65 patients with normal chromosome X and an excellent five-year EFS (100%) independently from the stage at diagnosis. The association between poor EFS and whole chromosome X alterations was confirmed after stratification into two groups of different expected prognosis and by internal validation via bootstrap analysis. Furthermore, the association was also observed in an independent cohort of NB patients extracted from the data set of the National Cancer Institute TARGET Project for Neuroblastoma, but sample size was small (n = 75) and statistical significance was not achieved. CONCLUSIONS: Loss of whole chromosome X may represent a new prognostic marker for NB patients with an NCA genomic profile. If confirmed by further studies, this finding could indicate that such patients should be reclassified as intermediate risk and treated accordingly.

Polypeptide Polymer Brushes by Light-Induced Surface Polymerization of Amino Acid N-Carboxyanhydrides.

Silicon wafers are decorated with photoamine generator 4,5-dimethoxy-2-nitrobenzyl 3-(triethoxysilyl)propyl carbamate. UV-irradiation in the presence of benzyl-l-glutamate N-carboxyanhydride is carried out, resulting in the release of the surface-bound primary amines, making them viable N-carboxyanhydride (NCA) polymerization initiators. Successful polypeptide grafting is confirmed by water contact angle measurements as well as by ellipsometry, revealing a poly(benzyl-l-glutamate) (PBLG) layer of ≈3 nm. X-ray photoelectron spectroscopy confirms the presence of amide groups in the grafted PBLG while time-of-flight secondary ion mass spectroscopy provides additional evidence for the presence of PBLG on the surface. Evaluation of negative control samples confirms successful UV surface grafting. The approach is thus established as a viable general method for light exposure directable polypeptide functionalization of silicon surfaces.

Analyzing Relationships of Necessity Not Just in Kind But Also in Degree: Complementing fsQCA With NCA.

Analyzing relationships of necessity is important for both scholarly and applied research questions in the social sciences. An often-used technique for identifying such relationships-fuzzy set Qualitative Comparative Analysis (fsQCA)-has limited ability to make the most out of the data used. The set-theoretical technique fsQCA makes statements in kind (e.g., "a condition or configuration is necessary or not for an outcome"), thereby ignoring the variation in degree. We propose to apply a recently developed technique for identifying relationships of necessity that can make both statements in kind and in degree, thus making full use of variation in the data: Necessary Condition Analysis (NCA). With its ability to also make statements in degree ("a specific level of a condition is necessary or not for a specific level of the outcome"), NCA can complement the in kind analysis of necessity with fsQCA.

The vial kit formulation for preparation of no-carrier-added 131 I-MIBG.

We have developed a new set of lyophilized kits, composed of 3 different kits, for the instant preparation of no-carrier-added 131 I-MIBG in the clinic. We here discussed the formulation of the kits, optimization of radiolabelling, quality control of radiolabeled 131 I-MIBG, and studies of animal biodistribution. The no-carrier-added (nca) 131 I-MIBG injection could be prepared within 30 minutes in the clinic with the help of the lyophilized kits. The radiochemical purity and specific activity (SA) could achieve above 98% and 6700 MBq/mg, respectively.

Control efficacy of Ca-containing foliar fertilizers on bitter pit in bagged 'Fuji' apple and effects on the Ca and N contents of apple fruits and leaves.

BACKGROUND: The preharvest application of Ca-containing foliar fertilizers can reduce the incidence of bitter pit (BP) in apples and improve fruit quality by increasing the Ca content and decreasing both the N content and the N/Ca ratio in fruits. In this study, we aimed to investigate the control efficacy of Ca-containing fertilizers on the incidence of BP and their effects on the Ca and N contents in bagged 'Fuji' apples by spraying foliar fertilizer containing calcium chloride (CaCl2 ), calcium nitrate [Ca(NO3 )2 ] or calcium formate [Ca(HCOO)2 ] at an early stage, five days after full bloom (DAFB) and 40 DAFB, and at a late stage, 80 DAFB and 125 DAFB. RESULTS: The incidences of BP were reduced significantly by 43.2-73.0%, and the efficacy of spraying at an early stage was significantly higher than that of spraying at a late stage. The Ca content of bagged apple fruits increased whereas the N content and N/Ca ratio decreased after spraying Ca-containing foliar fertilizers; however, the Ca content, N content and N/Ca ratio of apple leaves were differentially influenced. CONCLUSION: Foliar fertilizer containing CaCl2, Ca(NO3 )2 or Ca(HCOO)2 can be used at an early stage to control BP in apple and improve the quality of bagged apple fruits. © 2018 Society of Chemical Industry.

Highly efficient antibacterial diblock copolypeptides based on lysine and phenylalanine.

A series of amphiphilic diblock copolypeptides (K30 -b-F15 , K30 -b-F30 , and K30 -b-F45 ) were synthesized via N-carboxy-α-amino-anhydride ring-opening polymerization. The copolypeptides had excellent antibacterial efficacy to both Gram positive (S. aureus) and Gram negative (E. coli) bacteria. The minimum inhibitory concentrations (MICs) against E. coli and S. aureus are 8 µg mL-1 and 2 µg mL-1 , respectively, lower than most natural and artificial antimicrobial peptides (AMPs). The morphological changes of the bacteria treated with diblock copolypeptides were investigated by transmission electron microscopy; the results proved that the diblock copolypeptides had a similar antibacterial pore-forming mechanism to natural cationic peptides. This was confirmed by laser scanning confocal microscope images. CCK-8 results and the MICs showed that the diblock copolypeptides have high selectivity to bacteria, which suggested that the diblock copolypeptides could be excellent candidates to replace traditional antibiotics in future.