Research on the Upper Limit of Accuracy for Predicting Theoretical Tandem Mass Spectrometry

In recent years, numerous theoretical tandem mass spectrometry prediction methods have been proposed, yet a systematic study and evaluation of their theoretical accuracy limits have not been conducted. If the accuracy of current methods approaches this limit, further exploration of new prediction techniques may become redundant. Conversely, a need for more precise prediction methods or models may be indicated. In this study, we have experimentally analyzed the limits of accuracy at different numbers of ions and parameters using repeated spectral pairs and integrating various similarity metrics. Results show significant achievements in accuracy for backbone ion methods with room for improvement. In contrast, full-spectrum prediction methods exhibit greater potential relative to the theoretical accuracy limit. Additionally, findings highlight the significant impact of normalized collision energy and instrument type on prediction accuracy, underscoring the importance of considering these factors in future theoretical tandem mass spectrometry predictions.

Theoretical efficiency limit and realistic losses of indoor organic and perovskite photovoltaics [Invited]

Indoor organic and perovskite photovoltaics(PVs)have been attracting great interest in recent years.The theoretical limit of indoor PVs has been calculated based on the detailed balance method developed by Shockley–Queisser.However,realistic losses of the organic and perovskite PVs under indoor illumination are to be understood for further efficiency improvement.In this work,the efficiency limit of indoor PVs is calculated to 55.33%under indoor illumination(2700 K,1000 lux)when the bandgap(E_(g))of the semiconductor is 1.77 eV.The efficiency limit was obtained on the basis of assuming 100%photovoltaic external quantum efficiency(EQ_(EPV))when E≥E_(g),there was no nonradiative recombination,and there were no resistance losses.In reality,the maximum EQEPV reported in the literature is 0.80–0.90.The proportion of radiative recombination in realistic devices is only 10^(−5)–10^(−2),which causes the open-circuit voltage loss(ΔV_(loss))of 0.12–0.3 V.The fill factor(FF)of the indoor PVs is sensitive to the shunt resistance(R_(sh)).The realistic losses of EQE_(PV),nonradiative recombination,and resistance cause the large efficiency gap between the realistic values(excellent perovskite indoor PV,32.4%;superior organic indoor PV,30.2%)and the theoretical limit of 55.33%.In reality,it is feasible to reach the efficiency of 47.4%at 1.77 eV for organic and perovskite photovoltaics under indoor light(1000 lux,2700 K)with V_(OC)=1.299 V,J_(SC)=125.33μA/cm^(2),and FF=0.903 when EQE_(PV)=0.9,EQE_(EL)=10^(−1),R_(s)=0.5Ωcm^(2),and R_(sh)=10^(4) kΩcm^(2).

Research and Safety Evaluation of Thallium in Cosmetic Products

By standard method to determine thallium content in 34 batches of cosmetic products sold in Shenzhen,including cushions and sunscreens for children,all results of samples are within the range of not detected to 0.62 mg/kg.By calculating the Maximum Theoretical Safety Limit,according to guidance of Scientific Committee on Consumer Safety(SCCS)of European Union and Toxicological Review of Thallium and Compounds 2009 of United States Environmental Protection Agency(EPA)to assess the risk of cosmetic products.As a result,if the mean concentration of thallium in different kind of cosmetic products does not exceed 0.031 mg/kg,the products will not show significant toxicological risk for consumers.