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Yiming Li

Publications and source records attributed to Yiming Li.

At least 19 recordsLinked to original sources

Leveraging protein language models for cross-variant CRISPR/Cas9 sgRNA activity prediction.

MOTIVATION: Accurate prediction of single-guide RNA (sgRNA) activity is crucial for optimizing the CRISPR/Cas9 gene-editing system, as it directly influences the efficiency and accuracy of genome modifications. However, existing prediction methods mainly rely on large-scale experimental data of a single Cas9 variant to construct Cas9 protein (variants)-specific sgRNA activity prediction models, which limits their generalization ability and prediction performance across different Cas9 protein (variants), as well as their scalability to the continuously discovered new variants. RESULTS: In this study, we proposed PLM-CRISPR, a novel deep learning-based model that leverages protein language models to capture Cas9 protein (variants) representations for cross-variant sgRNA activity prediction. PLM-CRISPR uses tailored feature extraction modules for both sgRNA and protein sequences, incorporating a cross-variant training strategy and a dynamic feature fusion mechanism to effectively model their interactions. Extensive experiments demonstrate that PLM-CRISPR outperforms existing methods across datasets spanning seven Cas9 protein (variants) in three real-world scenarios, demonstrating its superior performance in handling data-scarce situations, including cases with few or no samples for novel variants. Comparative analyses with traditional machine learning and deep learning models further confirm the effectiveness of PLM-CRISPR. Additionally, motif analysis reveals that PLM-CRISPR accurately identifies high-activity sgRNA sequence patterns across diverse Cas9 protein (variants). Overall, PLM-CRISPR provides a robust, scalable, and generalizable solution for sgRNA activity prediction across diverse Cas9 protein (variants). AVAILABILITY AND IMPLEMENTATION: The source code can be obtained from https://github.com/CSUBioGroup/PLM-CRISPR.

CRISPR-Cas Systems↗

Aggregation behaviors of gelatin with cationic gemini surfactant at air/water interface.

The dilational rheological properties of gelatin with cationic gemini surfactant 1,2-ethane bis(dimethyl dodecyl ammonium bromide) (C(12)C(2)C(12)) at air/water interface were investigated using oscillating barriers method at low frequency (0.005-0.1 Hz), which was compared with single-chain surfactant dodecyltrimethyl ammonium bromide (DTAB). The results indicate that the maximum dilational modulus and the film stability of gelatin-C(12)C(2)C(12) are higher than those of gelatin-DTAB. At high concentration of C(12)C(2)C(12) or DTAB, the dilational modulus of gelatin-surfactant system becomes close to that corresponding to pure surfactant, suggesting gelatin at interface is replaced by surfactant. This replacement is also observed by surface tension measurement. However, it is found that gelatin-C(12)C(2)C(12) system has two obvious breaks but gelatin-DTAB has not in surface tension isotherms. These phenomena are ascribed to the double charges and strong hydrophobicity of C(12)C(2)C(12). Based on these experimental results, a mechanism of gelatin-surfactant interaction at air/water interface is proposed.

Air↗

An evaluation of the International Diabetes Federation definition of metabolic syndrome in Chinese patients older than 30 years and diagnosed with type 2 diabetes mellitus.

The objective of the study was to determine the most accurate metabolic syndrome (MS) definition among the definitions proposed by the International Diabetes Federation (IDF), the Third Report of the National Cholesterol Education Program Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III [ATPIII]), and the World Health Organization (WHO) and to evaluate the cutoff point of waist circumference using the IDF definition for optimally defining MS in the Chinese population. One thousand thirty-nine Chinese patients older than 30 years and diagnosed with type 2 diabetes mellitus were investigated by randomized cluster sampling in the Shanghai downtown, and 1008 patients were analyzed in this study. Body mass measurements, resting blood pressure, fasting blood measures, and carotid atherosclerotic measurements including common carotid artery intima-media thickness (IMT) and carotid plaque were investigated. The IDF definition was compared with the other 2 definitions, and the carotid atherosclerosis was evaluated among the patients according to these definitions. (1) The MS prevalence was 50.0%, 55.7%, and 70.0% under the IDF, ATPIII, and WHO definitions, respectively. (2) The percentage of all the participants categorized as either having or not having the MS was 69.9% (under the IDF and ATPIII definitions) and 70.2% (under the IDF and WHO definitions). (3) Common carotid artery IMT of patients with MS determined by the IDF definition was thicker than those determined by the WHO and ATPIII definitions, and the percentage of carotid plaque of patients with MS determined by the IDF definition was greater than those determined by the WHO and ATPIII definitions. (4) When the cutoff point of waist circumference in men determined by the IDF definition was modified from 90 to 85 cm, common carotid artery IMT of the emerging male patients with MS was thicker than that of the male patients with MS determined by the original IDF definition. In conclusion, the prevalence of MS was 50.0%, 55.7%, and 70.0% under the IDF, ATPIII, and WHO definitions, respectively. The preferable IDF definition served as a better predictor of cardiovascular disease risk in the Chinese patients diagnosed with type 2 diabetes mellitus compared with the ATPIII and WHO definitions. The modified cutoff point of waist circumference in men under the IDF definition specific for the Chinese population (from 90 to 85 cm) might be more suitable for predicting atherosclerosis.

Aged↗

New ganoderic acids, bioactive triterpenoid metabolites from the mushroom Ganoderma lucidum.

Two new lanostanoids, 7-oxo-ganoderic acid Z (1) and 15-hydroxy-ganoderic acid S (2), were isolated from a lipophilic extract of the fruiting body of Ganoderma lucidum. The structures of both compounds were established by interpretation of their spectroscopic data. Compounds 1 and 2 both exhibited inhibitory activities against the HMG-CoA reductase and acyl CoA acyltransferase.

Agaricales↗

Insular shifts in body size of rice frogs in the Zhoushan Archipelago, China.

1. Differences in body size between mainland and island populations have been reported for reptiles, birds and mammals. Despite widespread recognition of insular shifts in body size in these taxa, there have been no reports of such body size shifts in amphibians. 2. We provide the first evidence of an insular shift in body size for an amphibian species, the rice frog Rana limnocharis. We found significant increases in body size of rice frogs on most sampled islands in the Zhoushan archipelago when compared with neighbouring mainland China. 3. Large body size in rice frogs on islands was significantly related to increased population density, in both breeding and non-breeding seasons. Increases in rice frog density were significantly related to higher resource availability on islands. Increased resource availability on islands has led to higher carrying capacities, which has subsequently facilitated higher densities and individual growth rates, resulting in larger body size in rice frogs. We also suggest that large body size has evolved on islands, as larger individuals are competitively superior under conditions of harsh intraspecific competition at high densities. 4. Increases in body size in rice frogs were not related to several factors that have been implicated previously in insular shifts in body size in other taxa. We found no significant relationships between body size of rice frogs and prey size, number of larger or smaller frog species, island area or distance of islands from the mainland. 5. Our findings contribute to the formation of a broad, repeatable ecological generality for insular shifts in body size across a range of terrestrial vertebrate taxa, and provide support for recent theoretical work concerning the importance of resource availability for insular shifts in body size.

Animals↗

Solution NMR study of environmental effects on substrate seating in human heme oxygenase: influence of polypeptide truncation, substrate modification and axial ligand.

Solution proton NMR has been used here to show that, as either the high-spin ferric, protohemin (PH) substrate complex at neutral pH, or the low-spin ferric, cyanide-inhibited PH substrate complex, the active site electronic and molecular structure of the 233- and 265-residue recombinant constructs of human heme oxygenase-1, hHO, are essentially indistinguishable. It is shown, moreover, that the equilibrium PH orientational isomerism about the alpha,gamma-meso axis is 1:1 in the water-ligated, resting-state complex, but changes to a 4:1 equilibrium ratio as the cyanide-inhibited complex, with the minor species in solution corresponding to the only one found in crystals. The introduction of significant PH orientational preference in the cyanide over the aquo complex is rationalized by the crystallographic observation for the same H2O and CN ligated complexes of rat heme oxygenase (rHO), where the steric tilt of the Fe-CN unit resulted in a approximately 1 A transition of PH into the hydrophobic interior, and stronger interaction of the vinyls with the HO matrix [M. Sugishima, H. Sakamoto, M. Noguchi, K. Fukugama, Biochemistry 42 (2003) 9898-9905]. 1H NMR spectra of the cyanide-inhibited PH complex are the most used, and most useful, for determining the distribution of orientational isomerism for PH in complexes of HO. Hence, it is imperative that the time-course of the spectra after sample preparation be considered in order to reach conclusions that relate isomeric seating of the heme with variable isomeric biliverdin products. The natural orientational isomerism of PH leads to spectral congestion that has prompted the use of a synthetic, twofold symmetric substrate, 2,4-dimethyldeuterohemin, DMDH. While the hyperfine shift pattern for non-ligated residues are very similar and are consistent with largely conserved molecular structure with the alternate substrates, the steric tilt of the Fe-CN vector towards the protein interior, as determined by the orientation of the major magnetic axes, is 2 degrees smaller for DMDH than PH, and is rationalized by the substrate translating even further into the hydrophobic interior in the cyanide complex when the bulky vinyl groups are replaced by methyl groups.

Cyanides↗

Aggregation of poly(ethylene oxide)-poly(propylene oxide) block copolymers in aqueous solution: DPD simulation study.

The dissipative particle dynamics (DPD) simulation method was applied to simulate the aggregation behavior of three block copolymers, (EO)16(PO)18, (EO)8(PO)18(EO)8, and (PO)9(EO)16(PO)9, in aqueous solutions. The results showed that the size of the micelle increased with increasing concentration. The diblock copolymer (EO)16(PO)18 would form an intercluster micelle at a certain concentration range, besides the traditional aggregates (spherical micelle, cylindrical micelle, and lamellar phase); while the triblock copolymer (EO)8(PO)18(EO)8 would form a spherical micelle, cylindrical micelle, and lamellar phase with increasing concentration, and (PO)9(EO)16(PO)9 would form intercluster aggregates, as well as a spherical micelle and gel. New mechanisms were given to explain the two kinds of intercluster micelle formed by the different copolymers. It is deduced from the end-to-end distance that the morphologies of the diblock copolymer and triblock copolymer with hydrophilic ends were more extendible than the triblock copolymer with hydrophobic ends.

Computer Simulation↗

Ultra-high-yield growth of vertical single-walled carbon nanotubes: Hidden roles of hydrogen and oxygen.

An oxygen-assisted hydrocarbon chemical vapor deposition method is developed to afford large-scale, highly reproducible, ultra-high-yield growth of vertical single-walled carbon nanotubes (V-SWNTs). It is revealed that reactive hydrogen species, inevitable in hydrocarbon-based growth, are damaging to the formation of sp(2)-like SWNTs in a diameter-dependent manner. The addition of oxygen scavenges H species and provides a powerful control over the C/H ratio to favor SWNT growth. The revelation of the roles played by hydrogen and oxygen leads to a unified and universal optimum-growth condition for SWNTs. Further, a versatile method is developed to form V-SWNT films on any substrate, lifting a major substrate-type limitation for aligned SWNTs.

Journal Article↗

Solution structure of BmP08, a novel short-chain scorpion toxin from Buthus martensi Karsch.

A novel short-chain scorpion toxin BmP08 was purified from the venom of the Chinese scorpion Buthus martensi Karsch by a combination of gel-filtration, ion exchange, and reversed-phase chromatography. The primary sequence of BmP08 was determined using the tandem MS/MS technique and Edman degradation, as well as results of NMR sequential assignments. It is composed of 31 amino acid residues including six cysteine residues and shares less than 25% sequence identity with the known alpha-KTx toxins. BmP08 shows no inhibitory activity on all tested voltage-dependent and Ca(2+)-activated potassium channels. The 3D-structure of BmP08 has been determined by 2D-NMR spectroscopy and molecular modeling techniques. This toxin adopts a common alpha/beta-motif, but shows a distinctive local conformation and features a 3(10)-helix and a shorter beta-sheet. The unique structure is closely related to the distinct primary sequence of the toxin, especially to the novel arrangement of S-S linkages in the molecule, in which two disulfide bridges (C(i)-C(j) and C(i+3)-C(j+3)) link covalently the 3(10)-helix with one strand of the beta-sheet structure. The electrostatic potential surface analysis of the toxin reveals salt bridges and hydrogen bonds between the basic residues and negatively charged residues nearby in BmP08, which may be unfavorable for its binding with the known voltage-dependent and Ca(2+)-activated potassium channels. Thus, finding the target for this toxin should be an interesting task in the future.

Amino Acid Sequence↗

On the origin of preferential growth of semiconducting single-walled carbon nanotubes.

A correlation is observed between the diameters (d) of single-walled carbon nanotubes and the percentages of metallic and semiconducting tubes synthesized at 600 degrees C by plasma-assisted chemical vapor deposition. Small tubes (d approximately 1.1 nm) show semiconductor percentages that are much higher than expected for a random chirality distribution. Density functional theory calculations reveal differences in the heat of formation energies for similar-diameter metallic, quasi-metallic, and semiconducting nanotubes. Semiconducting tubes exhibit the lowest energies and the stabilization scales with approximately 1/d(2). This could be a thermodynamic factor in the preferential growth of small semiconducting nanotubes.

Journal Article↗

[Hydroxyapatite nanoparticles: a novel material of gene carrier].

Hydroxyapatite nanoparticles were prepared in low Ca/P ratio by a kind of electrodeposition-hydrothermal process. The suspension of nanoparticles was cultured with SGC-7901 cells; metabolically active cells were evaluated by MTT analysis. Cells grew well and the nanoparticles in the concentration range of 10-100 microg/ml had no adverse effect on the cell viability. The results show that the nanoparticles have excellent biocompatibility with cells. Agrose gel electrophoresis analysis demonstrated that the nanoparticles had the potential to adsorb EGFP-N1 at the pH ranging between 2 to 7. Nanoparticle-DNA complex could transfer EGFP-N1 into the SGC-7901 cells, and the confocal microscopy analysis revealed that the cells with green fluorescence showed the efficiency of nanoparticle uptake to be about 80% of the efficiency of the Lipofectmine TM 2 000 uptake. In vivo, nanoparticles and DNA-nanoparticle complex were injected into mice respectively via tail-vein, and the mice grew well in two weeks. The liver, kidney, and brain of the mice were sampled and detected with electron microscopy, and all of these exhibited biodistribution of nanoparticles. This study demonstrates that Hydroxyapatite nanoparticles could be used as gene carriers.

Animals↗

Cytotoxicity of a new toothpaste based on an ion exchange resin mixture.

PURPOSE: To evaluate the effects for cytotoxicity of two dentifrices: a toothpaste commercially available (Crest Extra-Whitening toothpaste) and a new experimental toothpaste based on a mixture of ion-exchange resins (named NMTD) that supplies calcium, fluoride, phosphate and zinc ions. METHODS: Cultures of mouse fibroblasts cells L929 were used in a MTT assay for in vitro cytotoxicity of the dentifrices. Cells were cultured in Eagle's minimal essential medium supplemented with 10% fetal bovine serum. Cultures were incubated at 37 degrees C in a humidified atmosphere of 5% CO2 and collected by tripsinization (0.05% trypsin/0.5mM EDTA). A 96-well microplate method was employed for the MTT colorimetric assay. Positive control consisted of 10 microl of phenol in 5 ml of 6% media, a dose that produces zero percent cell survival. Negative control was prepared by adding 0.5 ml of HBSS to 4.5 ml of 6% media. The plates were incubated for 24 and 48 hours at 37 degrees C in a 5% CO2 atmosphere. RESULTS: Means and standard deviations of absorbance values for each group and percentage inhibitory dosage (%ID) for each test material were calculated. None of the dentifrices resulted in a percentage of inhibition higher than 50% and did not observe marked increases in cytotoxicity with time of incubation. The positive control gave almost zero percent cell survival, whereas the negative control gave a hundred percent cell survival. Analysis of the results indicated that test dentifrice dose had no significant effect towards the cell viability (P<0.05).

Animals↗

1H NMR relaxation investigation of acetylcholinesterase inhibitors from huperzine A and derivative.

The binding properties of huperzine A (1) with Torpediniforms Nacline acetylcholinesterase (TnAChE) were investigated by (1)H NMR methods. The noselective, selective and double-selective spin-lattice relaxation rates were acquired in absent and present of TnAChE at a ratio [ligand]/[protein]=1:0.005. The selective relaxation rates shown protons of 1 had dipole-dipole interaction with protein active site protons. The motional correlation time of bound ligand was calculated by double-selective relaxation rate at 1 tau(2,3)=40.5 ns at 298 K, which showed 1 had high affinity with TnAChE. The experiments give a possible method to use TnAChE to locate the new huperzine A derivatives as AChE inhibitors.

Alkaloids↗

Remineralization potential of a new toothpaste formulation: an in vitro study.

The aim of the present study was to determine the ability of a dentifrice containing a mixture of ion-exchange resins (named NMTD), which supplies calcium, fluoride, phosphate, and zinc ions, to promote remineralization and/or inhibit demineralization of dental human enamel in a pH cycling model in vitro. A fluoride toothpaste was used as the control. The enamel specimens were tested for microhardness before and after 10 days and 16 days of the demineralizing and remineralizing treatments. The results of this study showed both dentifrices were effective in limiting in vitro enamel demineralization although the effects were not significantly different from each other. Inclusion of calcium and phosphate ion-exchange resins in the dentifrice containing a fluoride ion-exchange resin maintained a similar net outcome of the conventional dentifrice in the demineralization/remineralization process under the experimental conditions employed.

Analysis of Variance↗

The antimicrobial potential of 14 natural herbal dentifrices: results of an in vitro diffusion method study.

BACKGROUND: Increasing numbers of Americans are using natural herbal products for general and oral health care. Few of these products, however, have undergone rigorous testing, as evidenced by the limited amount of information on their safety and efficacy in the literature. The authors conducted an in vitro study to evaluate the antimicrobial potential of 14 natural herbal dentifrices. METHODS: The authors used a diffusion method to evaluate the antimicrobial effectiveness of 14 natural herbal dentifrices against four microorganisms: Streptococcus mutans, Streptococcus sanguis, Actinomyces viscosus and Candida albicans. Colgate Total (Colgate-Palmolive, New York City) and sterile pyrogen-free water served as the positive and negative controls, respectively. The authors tested the natural herbal dentifrices at full strength and at 1:1 dilution. They measured the zones of inhibition at 24 and 48 hours to evaluate the antimicrobial potential of the dentifrices. RESULTS: Six herbal dentifrices were effective in inhibiting the growth of all four microorganisms. The positive control produced significantly sized inhibition zones with all four microorganisms, while the negative control produced no observable zones. Six herbal dentifrices produced larger inhibition zones with A. viscosus than did the positive control. Six herbal dentifrices were inhibitory against C. albicans at full strength, but at 1:1 dilution, only three had such inhibitory effect. One herbal dentifrice produced microbial growth around and over the samples, indicating possible microbial contamination of the toothpaste. Only one herbal dentifrice showed consistent antimicrobial activity against all four microorganisms. CONCLUSIONS: The variation in antimicrobial inhibition among the herbal dentifrices indicates that more research is needed to validate their effectiveness claims. CLINICAL IMPLICATIONS: This study provides practitioners with insight into the claims of natural herbal dentifrices' antimicrobial effects.

Actinomyces viscosus↗

Comparative tooth whitening efficacy of 18% carbamide peroxide liquid whitening gel using three different regimens.

OBJECTIVE: Recently, a novel paint-on liquid whitening gel--Colgate Simply White Clear Whitening Gel--which contains 18% carbamide peroxide, has been developed as a self-administered tooth bleaching system. The purpose of the present study was to determine the efficacy and safety of this product using alternate exaggerated or simplified treatment regimens. METHODOLOGY: This was a three-week clinical trial using a parallel, double-blind, stratified protocol with three different instructions for application: 1) twice-daily, no air-drying, and 15 minutes without eating/drinking; 2) three times daily, 30-second air-drying and 30 minutes without eating/drinking; or 3) four times daily, 30-second air-drying and 30 minutes without eating/drinking. One-hundred and twenty (120) healthy volunteers were balanced into three equal groups based on shade scores (A3 or darker). Clinical evaluations (shade guide, oral tissue health, gingival index and visual analog sensitivity score) were performed on each group at baseline and weekly for the next 21 days. At the conclusion of the study, a survey of the subjects' opinions on their assigned product regimen was also conducted. RESULTS: Subjects who used Colgate Simply White Clear Whitening Gel three and four times daily achieved the greatest shade improvement (5.88 +/- 1.53 shades, and 5.57 +/- 1.54, respectively). However, these values were only about one shade better than the value observed for the more convenient, twice-daily, "no-dry" regimen (4.51 +/- 1.77 shades), though they were statistically significant (p < 0.05). The result for the four-times daily protocol was not statistically different from the three-times group. Also, no differences were observed between the groups concerning oral tissue health, gingival index or tooth sensitivity, and no adverse effects were observed or reported regardless of the regimen used. Surveys completed by the subjects showed that those who used the twice-daily, "no-dry" regimen found the product to be the easiest to use, the most comfortable and the most pleasant tasting. CONCLUSION: It can be concluded from the clinical data that three or four applications of Colgate Simply White Clear Whitening Gel per day provided better efficacy. In addition, the use of the whitening gel twice daily, even without "dry time" and only 15 minutes without eating/drinking, yielded results that were comparable to previously reported results using the original on-label directions. The potential additional benefit to the "simplified regimen" is that it was perceived to be the most convenient and comfortable. The use of Colgate Simply White Clear Whitening Gel up to four times daily for up to three weeks is also safe, and the tendency of abusing the product with more frequent daily use may be deterred by the inconvenience reported by the study subjects.

Adult↗

1H NMR investigation of the solution structure of substrate-free human heme oxygenase: comparison to the cyanide-inhibited, substrate-bound complex.

1H NMR was used to investigate the molecular structure, and dynamic properties of soluble, recombinant, substrate-free human heme oxygenase (apohHO) on a comparative basis with similar studies on the substrate complex. Limited but crucial sequence-specific assignments identify five conserved secondary structural elements, and the detection of highly characteristic dipolar or H-bond interactions among these elements together with insignificant chemical shift differences confirm a strongly conserved folding topology of helices C-H relative to that of substrate complexes in either solution or the crystal. The correction of the chemical shifts for paramagnetic and porphyrin ring current influences in the paramagnetic substrate complex reveals that the strength of all but one of the numerous relatively robust H-bonds are conserved in apohHO, and similar ordered water molecules are located near these H-bond donors as observed in the substrate complexes. The unique and significant weakening of the Tyr(58) OH hydrogen bond to the catalytically critical Asp(140) carboxylate in apohHO is suggested to arise from the removal of the axial H-bond acceptor ligand rather than the loss of substrate. The interhelical positions of the conserved strong H-bonds argue for a structural role in maintaining a conserved structure for helices C-H upon loss of substrate. While the structure and H-bond network are largely conserved upon loss of substrate, the variably increased rate of NH lability dictates a significant loss of dynamic stability in the conserved structure, particularly near the distal helix F.

Aspartic Acid↗

Solution 1H, 15N NMR spectroscopic characterization of substrate-bound, cyanide-inhibited human heme oxygenase: water occupation of the distal cavity.

A solution NMR spectroscopic study of the cyanide-inhibited, substrate-bound complex of uniformly (15)N-labeled human heme oxygenase, hHO, has led to characterization of the active site with respect to the nature and identity of strong hydrogen bonds and the occupation of ordered water molecules within both the hydrogen bonding network and an aromatic cluster on the distal side. [(1)H-(15)N]-HSQC spectra confirm the functionalities of several key donors in particularly robust H-bonds, and [(1)H-(15)N]HSQC-NOESY spectra lead to the identification of three additional robust H-bonds, as well as the detection of two more relatively strong H-bonds whose identities could not be established. The 3D NMR experiments provided only a modest, but important, extension of assignments because of the loss of key TOCSY cross-peaks due to the line broadening from a dynamic heterogeneity in the active site. Steady-state NOEs upon saturating the water signal locate nine ordered water molecules in the immediate vicinity of the H-bond donors, six of which are readily identified in the crystal structure. The additional three are positioned in available spaces to account for the observed NOEs. (15)N-filtered steady-state NOEs upon saturating the water resonances and (15)N-filtered NOESY spectra demonstrate significant negative NOEs between water molecules and the protons of five aromatic rings. Many of the NOEs can be rationalized by water molecules located in the crystal structure, but strong water NOEs, particularly to the rings of Phe47 and Trp96, demand the presence of at least an additional two immobilized water molecules near these rings. The H-bond network appears to function to order water molecules to provide stabilization for the hydroperoxy intermediate and to serve as a conduit to the active site for the nine protons required per HO turnover.

Cyanides↗