Single-point Method Research Articles

Analysis of Vibration of Roadheader Rotary Table Based on Finite Element Method and Data from Underground Coalmine

The intense vibration of a roadheader rotary table damages the cutting system of the roadheader and reduces the efficiency. This paper analyzes the vibration of a rotary table by combining the finite element model with tested data from an underground coalmine. First, the force of the rotary table during the cutting procedure was analyzed, and the finite element model was built using Pro/E and ADAMS. The tested data were then imported into the model after selection, procession, and combination were conducted. Next, the six lowest‐order parameters of the rotary table were calculated. A vibration analysis of the rotary table under certain working conditions was conducted, and the results were compared with those from a modal experiment using a single‐point excitation method. According to the comparison between the simulation result and experiments, it is clear that this method is both reasonable and feasible. And it could supplement the theoretical foundation of the analysis of other roadheader components, providing reference for the improvement of the structure and dynamic properties of a roadheader. In addition, other vibration components of a roadheader such as the cutting head and the cutting arm could also be analyzed through the proposed method, with very reliable precision.

Single-point reactive power control method on voltage rise mitigation in residential networks with high PV penetration

Abstract Voltage rise (VR) due to reverse power flow is an important obstacle for high integration of Photovoltaic (PV) into residential networks. This paper introduces and elaborates a novel methodology of an index-based single-point-reactive power-control (SPRPC) methodology to mitigate voltage rise by absorbing adequate reactive power from one selected point. The proposed index utilizes short circuit analysis to select the best point to apply this Volt/Var control method. SPRPC is supported technically and financially by distribution network operator that makes it cost effective, simple and efficient to eliminate VR in the affected network. With SPRPC none of the previous PV inverters need to upgrade and can retain their unity power factor to not to conflict with current grid codes. Comprehensive 24-h simulation studies are done on a modified IEEE 69-bus Network emulating a traditional residential power system with high r/x ratio. Efficacy, effectiveness and cost study of SPRPC is compared to droop control to evaluate its advantages.

A novel calibration method based on Kirchhoff theory for piezoelectric dynamometer

PurposeThis paper aims to improve calibration and force measurement accuracy of multi-sensors’ piezoelectric dynamometer used in thrust measurement of rocket/air vehicle engine.Design/methodology/approachThis paper presents a mapping solution method of sensors’ outputs based on the Kirchhoff thin plate theory, builds force-deformation differential equations with specific boundary conditions, uses finite difference (FD) method to solve the equations and analyzes outputs in offset loading forces in four-sensor square layout in main direction. The resultant force deviations calculated by the Kirchhoff theory are optimized with sequence quadratic program (SQP) method, and a calibration method of multiple loading points (MLP) based on the Kirchhoff theory is presented. Experiments of static calibration and verification are complemented to contrast the novel and single loading point (SLP) calibration method.FindingsExperiments of static calibration and its verification show that at a loading force of 5,000N, the average resultant force deviations with MLP is 17.87N (0.35% FS) compared with single loading point method 26.45N (0.53% FS), improving calibration and measurement precision.Originality valueA novel calibration method with MLP is presented. Force distributions of multiple sensors of main direction in piezoelectric dynamometer with offset loading force are solved with the Kirchhoff theory. The resultant force deviations calculated by Kirchhoff theory are optimized with the SQP method.

Iohexol plasma clearance in children: validation of multiple formulas and single-point sampling times

BackgroundThe non-ionic agent iohexol is increasingly used as the marker of choice for glomerular filtration rate (GFR) measurement. Estimates of GFR in children have low accuracy and limiting the number of blood-draws in this patient population is especially relevant. We have performed a study to evaluate different formulas for calculating measured GFR based on plasma iohexol clearance with blood sampling at only one time point (GFR1p) and to determine the optimal sampling time point.MethodsNinety-six children with chronic kidney disease (CKD) stage 1–5 (median age 9.2 years; range 3 months to 17.5 years) were examined in a cross-sectional study using iohexol clearance and blood sampling at seven time points within 5 h (GFR7p) as the reference method. Median GFR7p was 66 (range 6–153) mL/min/1.73 m2. The performances of six different single time-point formulas (Fleming, Ham and Piepsz, Groth and Aasted, Stake, Jacobsson- and Jacobsson-modified) were validated against the reference. The two-point GFR (GFR2p) was calculated according to the Jødal and Brøchner–Mortensen formula.ResultsThe GFR1p calculated according to Fleming with sampling at 3 h (GFR1p3h-Fleming) had the best overall performance, with 82% of measures within 10% of the reference value (P10). In children with a GFR ≥ 30 mL/min/1.73 m2 (n = 78), the GFR1p3h-Fleming had a P10 of 92.3%, which is not significantly different (p = 0.29) from that of GFR2p (P10 = 96.2%). Considerable differences within and between the different formulas were found for different CKD stages and different time points for blood sampling.ConclusionsFor determination of mGFR in children with CKD and an assumed GFR of ≥ 30 mL/min/1.73 m2 we recommend GFR1p3h-Fleming as the preferred single-point method as an alternative to GFR2p. For children with a GFR < 30 mL/min/1.73 m2, we recommend the slope-GFR with at least two blood samples.Clinical Trial Registration: ClinicalTrials.gov, Identifier NCT01092260, https://clinicaltrials.gov/ct2/show/NCT01092260?term=tondel&rank=2

Research on conditional characteristics vision real‐time detection system for conveyor belt longitudinal tear

Conveyor belt longitudinal tear is one of the most serious problems in coal mining. Existing systems cannot realise lossless and real-time detection for longitudinal tear of conveyor belt. Currently, visual detecting systems are proposed by many researchers and are becoming the future trend. A visual recognition system based on using laser and area light sources is designed in this study, which can recognise and count abrasions, incomplete-tears, and complete-tears. The advantage of the system is to prevent longitudinal tear based on multi-feature information. In the process of detecting conditional characteristics, laser and area light sources are responsible for enhancing contrast between conditional features and conveyor belt surface, meanwhile false corner filtration and single-point feature identification method are designed for improving recognition accuracy of the system. Compared with several current systems, the designed system has a better performance on recognising complex tear characteristics of conveyor belt, thus the problem of starting warning only based on single feature can be effectively avoided.

Improved results on BIBO stability and stabilization of networked control systems with short time-varying delays

Based on the multiple nominal points method (MNPM), the problems of BIBO stability and BIBO stabilization for networked control systems (NCSs) with short time-varying delays (STVDs) are researched, and some improved results are obtained in this article. Using the single nominal point method, a NCS with STVDs is modeled as a time-varying uncertain discrete system, in which the uncertain parameters are norm bounded and with single nominal point. Applying the small gain theorem to this model, an improved BIBO stability criterion of the NCS is obtained. To further reduce the conservativeness arising from STVDs, the uncertain parameters are modeled as N norm bounded uncertainties based on the MNPM. The presented stability criteria depend on the bounds of STVDs. Furthermore, the controller design methods are also provided. A numerical example is given to show that the proposed methods are better than existing ones.

Photobiomodulation therapy action in wound repair skin induced in aged rats old: time course of biomarkers inflammatory and repair.

Previous studies have discussed an inverse correlation between age and wound healing, because it relates to the association of aging with a gradual decrease in healing capacity. Treatment with photobiomodulation therapy (PBMT) improves wound healing by inducing increases in mitotic activity, numbers of fibroblasts, collagen synthesis, and neovascularization. Therefore, this study aimed to evaluate the effects of PBMT in cutaneous wound healing in aged rats. A punch biopsy of 8mm in diameter was performed to produce a skin wound. The study included 45 male rats, of which 15 were young (30days) and 30 were elderly (500days). The 45 animals were distributed into 3 experimental groups, which were subjected to skin wounds and 1 aged group received PBMT, with a 30-mW laser beam (power density of 1.07W/cm2), beam area of 0.028cm2, and λ660nm produced through active phosphide Gallium-Aluminum-Indio (InGaAIP). The PBMT application took the form of a single-point transcutaneous method, with a total energy of 2 joules per wound site, energy density of 72J/cm2, and time of 1min and 7s. Analysis was performed to verify the effect of PBMT on the quantity of collagen I and III, metalloproteinase 3 and 9 (MMP-3 and MMP-9), tissue inhibitor of metalloproteinase-2 (TIMP-2) and of vascular endothelial growth factor (VEGF) at the wound site by immunohistochemistry, cytokine-induced neutrophil chemoattractant (CINC)-1, by enzyme-linked immunosorbent assay (ELISA) and interleukin (IL)-6 real-time polymerase chain reaction (RT-PCR). That we conclude LLLT is effective in the modulation of inflammatory mediators IL-6, CINC-1, VEGF, MMP-3, MMP-9 and TIMP-2 as well as increased collagen production in aged animals during different phases of the tissue regeneration process. However, the effects of PBMT obtained in the aged animals (aged LLLT group) suggest that new dosimetries should be tested to achieve better results.

Synthesis of zeolite/magnetite nanocomposite and a fast experimental determination of its specific surface area

In the present work, the clinoptilolite was magnetized by magnetite nano-powder synthesized by chemical co-precipitation route. The clinoptilolite/magnetite nanocomposites were prepared with different weight ratios of 7 : 1, 5 : 1, 3 : 1 and 1 : 1 using FeCl3 · 6H2O and FeCl2 · 4H2O in an aqueous phase under the ambient condition. The nanocomposites were characterized by the X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and the vibrating sample magnetometer techniques. The results of characterization suggest that the main magnetic phase present in the nanocomposite is magnetite nanoparticle with an average diameter of 18–23 nm and the saturation magnetization of 74.29 emu g–1. The specific surface area was calculated by a BET single-point method as a rapid and accurate way which can lie almost anywhere on the isotherm. The values of the specific surface area obtained by the BET single-point method were in a good agreement with the BET multiple-point method. It was found that the BET single-point method is faster and simpler than the BET multiple-point method for routine applications. Also, increasing Fe3O4 content caused an increase in the specific surface area of the nanocomposites.

Tool positioning method for achieving double-point contact in flank milling of a concave surface with a barrel cutter

This paper presents a novel tool positioning method for flank milling with a barrel cutter. It can be used to compute the tool position, at which the cutter can contact with the surface at two points. The strip width of the tool position is larger than that of the tool position solved by the single-point offset method. An error distribution curve was used to describe the gap between a barrel cutter and a surface. This paper presented the existence of the tool position with double contact points through analyzing different types of error distribution curves. The cutter was lifted from the surface firstly, and then, the tool orientation was adjusted by changing the tilt angle and the yaw angle. The method presented was applied on a rule surface, a sculptured surface, and a pressure surface of a blade. The tool positions were analyzed to demonstrate the validity of our method. The computation and simulation results indicate that the double-point contact tool position can be solved by our method.

Preparation and basic properties of superhydrophobic silicone rubber with micro-nano hierarchical structures formed by picosecond laser-ablated template

Hydrophobicity is the most important property of silicone rubber for outdoor isolation. Controlling wettability, along with interface and adhesion studies, has been widely investigated for technological applications, such as self-cleaning surfaces, by modifying the geometric structure and chemical composition of surfaces. Superhydrophobic surface with self-cleaning and anti-icing properties is ideal for outdoor insulation material. This paper reports on an effective strategy to modify the surface structure of silicone rubber. Microcraters with nanotexture can be fabricated on a mold steel using high-power picosecond laser incorporated with a high-speed scanning mirror. This template is used in direct replication process in which the surface morphology of silicone rubber can be changed during vulcanization. Two accessible methods are used to implement the modification process. Single-point pulse method is used to prepare regular papilla and abundant nanotexture on open architecture-type superhydrophobic surface, with contact angle reaching 151.5°±1.7°. Line scanning method is used to prepare connected papillae on enclosed-type surface, forming the secondary structure. In this case, nanotexture is richer and has a smaller scale (100 nm) compared with open architecture-type surface. Moreover, the contact angle of the enclosed-type superhydrophobic surface is 150.3°±0.9°. The contact model of water on superhydrophobic surfaces follows the Wenzel and Cassie coexisting model as shown by the air pockets, which are found experimentally and by calculation. Sliding angle of superhydrophobic surfaces reaches 5°, which indicates that this insulating surface possesses good self-cleaning properties. Repeated and large-area fabrication of superhydrophobic silicone rubber can be achieved by the proposed methods. These methods can be performed for large-scale application.

Study on the Vibration Performance of a Multi-layer Flat Restrained Damping Structure

In this paper, the composite loss factor, vibration acceleration level and displacement of a multi-layer flat-shaped constrained damping structure are studied by means of the single-point hammer excitation method and the modal strain energy method. The influence of the number of damping layers on the damping performance of the constrained damping structure is discussed, and the optimal number of layers is determined. The experimental results show that with the increase of the number of damping layers, the loss factor gradually increases, but the increasing range decreases gradually. The loss factor obtained in this study is 0.049, 0.028, and 0.022 respectively. The maximum vibration acceleration level is 15dB, 3dB and 4dB respectively. In addition, the maximum displacement of the structure calculated by the modal strain energy method shows a decreasing trend, which is 0.542, 0.546, 0.383, and 0.264, respectively. The composite loss factor has the same trend as that obtained from the experimental results, with an error very close to 20%. The higher level error is slightly larger, but still less than 25% with good consistency. The results show that the damping effect of the multi-layer plate type confinement damping structure is better than that of the single-layer damping structure. The optimal number of layers is 3.

Histological validation of fast macromolecular proton fraction mapping as a quantitative myelin imaging method in the cuprizone demyelination model

Cuprizone-induced demyelination in mice is a frequently used model in preclinical multiple sclerosis research. A recent quantitative clinically-targeted MRI method, fast macromolecular proton fraction (MPF) mapping demonstrated a promise as a myelin biomarker in human and animal studies with a particular advantage of sensitivity to both white matter (WM) and gray matter (GM) demyelination. This study aimed to histologically validate the capability of MPF mapping to quantify myelin loss in brain tissues using the cuprizone demyelination model. Whole-brain MPF maps were obtained in vivo on an 11.7T animal MRI scanner from 7 cuprizone-treated and 7 control С57BL/6 mice using the fast single-point synthetic-reference method. Brain sections were histologically stained with Luxol Fast Blue (LFB) for myelin quantification. Significant (p < 0.05) demyelination in cuprizone-treated animals was found according to both LFB staining and MPF in all anatomical structures (corpus callosum, anterior commissure, internal capsule, thalamus, caudoputamen, and cortex). MPF strongly correlated with quantitative histology in all animals (r = 0.95, p < 0.001) as well as in treatment and control groups taken separately (r = 0.96, p = 0.002 and r = 0.93, p = 0.007, respectively). Close agreement between histological myelin staining and MPF suggests that fast MPF mapping enables robust and accurate quantitative assessment of demyelination in both WM and GM.

Study on the prognosis of propofol after reperfusion in patients with replantation surgery

Objective To evaluate the influence of different concentrations of propofol on ischemia/reperfusion(I/R) replantation surgery prognosis of patients. Methods Ninety patients that had done replantation surgery were included. All patients were the ASA grade statusⅠor Ⅱ. Ninety patients were randomly divided into three groups(n=30), low concentration group (group L), high concentration group (group H) and control group(group C). All patients in all coracoid single point method brachial plexus, nerve stimulator to locate. Limb were compared in plasma malondialdehyde(MDA), ischemia modified albumin(IMA), concentration of superoxide dismutase(SOD) three indicators. Patients were followed up for a week after surgery were compared the incidence of vascular crisis and survival. Analyzed and summarized the prognosis of different concentrations of propofol anesthesia. Results One hour after anesthesia after tourniquet, the concentration of IMA and MDA in group H and group L were both significantly lower than group C, compare with a significant difference(P<0.05), SOD value in group H after 1 h and L group was significantly lower(P<0.05). After a week of follow-up found that the incidence of vascular crisis in H group and group L were significantly lower than group C, compare with a significant difference[χ2(LC)=4.523, P(LC)=0.033, χ2(HC)=9.871, P(HC)=0.005]. The survival in group H and group L were both significantly higher than finger group C, compare with a significant difference[χ2(LC)=3.857, P(LC)=0.049, χ2(HC)=6.857, P(HC)=0.009]. Conclusions The propofol has played a very good anaesthesia effect in ischemia/reperfusion (I/R) , propofol can improve the survival rate after replantation of I/R, and high concentration of propofol can better improve the prognosis. Key words: Replantation; Propofol; Ischemia/reperfusion

Effect of Preparation Parameters on Methylene blue number of Activated Carbons Prepared from a Locally Available Material

The adsorption of Methylene blue by the activated carbons prepared from a locally available material Lapsi Seed Stone has been studied. Various activated carbons were prepared by varying the parameters such as ratio of Lapsi seed stone particles to Phosphoric acid, carbonization temperature and carbonization time. Determination of Methylene blue numbers of the activated carbons was done by single point method by batch mode. Methylene blue number is found to be affected by the various preparation conditions like carbonization temperature, carbonization time, ratio of activating agent and Lapsi seed stone particles and the concentration of phosphoric acid. The optimum conditions for the preparation of activated carbon are found to be carbonization temperature 400°C for 4 hours at the ratio of 1:1 Lapsi seed stone particles and Phosphoric acid.Journal of the Institute of Engineering, 2016, 12(1): 169-174

Carbon dioxide and methane measurements from the Los Angeles Megacity Carbon Project - Part 1: calibration, urban enhancements, and uncertainty estimates.

We report continuous surface observations of carbon dioxide (CO2) and methane (CH4) from the Los Angeles (LA) Megacity Carbon Project during 2015. We devised a calibration strategy, methods for selection of background air masses, calculation of urban enhancements, and a detailed algorithm for estimating uncertainties in urban-scale CO2 and CH4 measurements. These methods are essential for understanding carbon fluxes from the LA megacity and other complex urban environments globally. We estimate background mole fractions entering LA using observations from four “extra-urban” sites including two “marine” sites located south of LA in La Jolla (LJO) and offshore on San Clemente Island (SCI), one “continental” site located in Victorville (VIC), in the high desert northeast of LA, and one “continental/mid-troposphere” site located on Mount Wilson (MWO) in the San Gabriel Mountains. We find that a local marine background can be established to within ~1 ppm CO2 and ~10 ppb CH4 using these local measurement sites. Overall, atmospheric carbon dioxide and methane levels are highly variable across Los Angeles. “Urban” and “suburban” sites show moderate to large CO2 and CH4 enhancements relative to a marine background estimate. The USC (University of Southern California) site near downtown LA exhibits median hourly enhancements of ~20 ppm CO2 and ~150 ppb CH4 during 2015 as well as ~15 ppm CO2 and ~80 ppb CH4 during mid-afternoon hours (12:00–16:00 LT, local time), which is the typical period of focus for flux inversions. The estimated measurement uncertainty is typically better than 0.1 ppm CO2 and 1 ppb CH4 based on the repeated standard gas measurements from the LA sites during the last 2 years, similar to Andrews et al. (2014). The largest component of the measurement uncertainty is due to the single-point calibration method; however, the uncertainty in the background mole fraction is much larger than the measurement uncertainty. The background uncertainty for the marine background estimate is ~10 and ~15 % of the median mid-afternoon enhancement near downtown LA for CO2 and CH4, respectively. Overall, analytical and background uncertainties are small relative to the local CO2 and CH4 enhancements; however, our results suggest that reducing the uncertainty to less than 5 % of the median mid-afternoon enhancement will require detailed assessment of the impact of meteorology on background conditions.

Theoretical study of OCCHCN as a potential alternative insulation gas for SF6

Cyanoketene (OCCHCN) has been reported as a potential alternative insulation gas for SF6 in Patent US0135817. Stationary point equilibrium geometries on the ground state have been optimized at the B3LYP/6-311+G(d,p) level, and the harmonic vibration frequencies are calculated at the same level. The HOMO-LUMO energy gaps (Eg), ionization potentials (IP), and electron affinities (EA) of the studied molecules are obtained. The minimum energy path (MEP) is obtained by the intrinsic reaction coordinate (IRC) theory, and the energetic information is further refined by QCISD(T) (single-point) method. The results show that OCCHCN can be used as SF6 alternative insulation gas in high voltage equipment according to potential energy surface analysis. As the isomerization and the cleavage reactions potential barriers are lower than the Eg and IP values, resulting in OCCHCN is not easy to be ionized and excited.

Probe Positioning for the Exhaust Emissions Measurements

Emission of harmful compounds in the exhaust gases depends on the operating conditions of the engine and its technical condition. Therefore, the legislative activity is focused on the introduction of new diagnostic and research procedures. The preferred method is using probes with plurality of holes for multi-gas sampling from the entire cross-section of exhaust stream. This method appears to vitiated by an error caused by averaging dilution and sampling gas from the very beginning of the measurement path. The results of measurements contained in the article are related to changes in the concentration of harmful substances in exhaust gases depending on the distance from the axis of the jet. In the article the disadvantages of this the methods were highlighted and the single-point measurement method was proposed.

Evaluating single-point quantitative magnetization transfer in the cervical spinal cord: Application to multiple sclerosis.

Spinal cord (SC) damage is linked to clinical deficits in patients with multiple sclerosis (MS), however, conventional MRI methods are not specific to the underlying macromolecular tissue changes that may precede overt lesion detection. Single-point quantitative magnetization transfer (qMT) is a method that can provide high-resolution indices sensitive to underlying macromolecular composition in a clinically feasible scan time by reducing the number of MT-weighted acquisitions and utilizing a two-pool model constrained by empirically determined constants. As the single-point qMT method relies on a priori constraints, it has not been employed extensively in patients, where these constraints may vary, and thus, the biases inherent in this model have not been evaluated in a patient cohort. We, therefore, addressed the potential biases in the single point qMT model by acquiring qMT measurements in the cervical SC in patient and control cohorts and evaluated the differences between the control and patient-derived qMT constraints (kmf, T2fR1f, and T2m) for the single point model. We determined that the macromolecular to free pool size ratio (PSR) differences between the control and patient-derived constraints are not significant (p > 0.149 in all cases). Additionally, the derived PSR for each cohort was compared, and we reported that the white matter PSR in healthy volunteers is significantly different from lesions (p < 0.005) and normal appearing white matter (p < 0.02) in all cases. The single point qMT method is thus a valuable method to quantitatively estimate white matter pathology in MS in a clinically feasible scan time.

Bioavailability assessment of thiacloprid in soil as affected by biochar

Biochars can significantly sorb pesticides, and reduce their bioavailability in agricultural soils. In this study, the effects of a type of biochar (BC500) on the sorption, degradation, bioaccumulation and bioavailability of thiacloprid, which is a commonly used insecticide, were investigated. The thiacloprid sorption constant (Kf values) increased by 14 times after 2% BC500 application, and the degradation of the insecticide decreased with increasing amounts of the biochars in the soil. Coupled with the exhaustive extraction and single-point Tenax method, the bioavailability of thiacloprid was predicted in the presence of the biochar. In soils amended with BC500, the thiacloprid concentrations accumulated in Tenax correlated well with those observed in earthworms (R2 = 0.887), whereas the concentrations extracted by exhaustive method followed a less significant relationship with those in earthworms (R2 = 0.624). The results of Tenax extractions and earthworm bioassays indicate that biochar reduces the bioavailability of thiacloprid in soil, but the delayed degradation and increased earthworm accumulation in aged biochar-amended soil imply that the environmental risks of biochar application to earthworms remain.

Understanding the insight into the mechanisms and dynamics of the Cl-initiated oxidation of (CH3)3CC(O)X and the subsequent reactions in the presence of NO and O2 (X = F, Cl, and Br)

In this work, the density functional and high-level ab initio theories are adopted to investigate the mechanisms and kinetics of reaction of (CH3)3CC(O)X (X = F, Cl, and Br) with atomic chlorine. Rate coefficients for the reactions of chlorine atom with (CH3)3CC(O)F (k1), (CH3)3CC(O)Cl (k2), and (CH3)3CC(O)Br (k3) are calculated using canonical variational transition state theory coupled with small curvature tunneling method over a wide range of temperatures from 250 to 1000 K. The dynamic calculations are performed by the variational transition state theory with the interpolated single-point energies method at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-311++G(d,p) level of theory. Computed rate constant is in good line with the available experimental value. The rate constants for the title reactions are in this order: k1<k2<k3, suggesting that the effect of halogen substitution on the mechanisms and dynamics is different. The subsequent and secondary reactions for the hydrogen abstraction intermediates are studied involving NO and O2 molecules in the atmosphere. The atmospheric lifetime and global warming potential (GWP) of (CH3)3CC(O)X (X = F, Cl, and Br) are estimated, and it shows that (CH3)3CC(O)F have larger GWP value than that of (CH3)3CC(O)Cl and (CH3)3CC(O)Br. Due to the presence of Cl and Br atoms, the environmental impact of (CH3)3CC(O)Cl and (CH3)3CC(O)Br may be given more concerns.