Dual-mode colorimetric and fluorescent detection of cobalt ions based on N, B co-doped carbon quantum dots and p-phenylenediamine derived nanoparticles.

Nitrogen, boron co-doped carbon quantum dots (gCQDs), and a coloration probe (PPD-NPs) with response to cobalt ions (Co2+) were prepared by using 4-hydroxyphenylboric acid as the common precursor, with ethylenediamine and p-phenylenediamine (PPD) adopted as nitrogen-doped reagents, respectively. A noticeable brown-to-purple color change can be observed with the addition of Co2+, and a broad absorption band emerges at 535 nm. At the same time, gCQDs, which is introduced as the fluorescence signal source, will be significantly quenched due to the enhanced inner filtration effect, induced by the overlap between the emission spectrum of gCQDs and the emerging absorption band. Therefore, a colorimetric/fluorescent dual-mode sensing probe for Co2+ is constructed by combining the recognition unit PPD-NPs and the fluorescent gCQDs into PPD-NP/gCQD. Under the optimized experimental conditions, the calculated limits of detection are 1.51 × 10-7 M and 3.75 × 10-7 M for the colorimetric mode and the fluorescence mode, respectively, well qualified for the determination of Co2+ maximum permitted level in drinking water. The feasibility of the proposed method has been verified in tap water, lake water, and black tea samples.

Convex optimization-based high-speed and security joint optimization scheme in optical access networks.

Data rate and security are essential performance metrics for passive optical networks (PON). However, existing optical access networks lack standardized metrics to evaluate rate and security performance uniformly. This paper introduces a high-speed and security joint optimization scheme for optical access networks using convex optimization. Evaluation metrics for data rate and security performance in PON are established. According to the evaluation metrics, the security optimization objective function Us, high-speed optimization objective function GMI, and high-speed security joint-optimization objective function Hs are established. An optimization problem is formulated to maximize weighted rate and security indicators, factoring in constraints such as maximum power, probability, amplifier capacity, normalized mutual information, and key and frame lengths. An alternating optimization method is applied to iteratively address sub-problems by exploiting successive convex approximations and differences of convex functions. This transforms non-convex sub-problems into convex optimizations. Experimental results highlight notable improvements in objective function values, confirming the effectiveness of the proposed high-speed security optimization algorithm for optical access networks.

Deep ultraviolet AlGaN-multiple quantum wells with photoluminescence enhanced by topological corner state.

The AlGaN-based deep ultraviolet light-emitting diode (DUV LED) has advantages of environmentally friendly materials, tunable emission wavelength, and easy miniaturization. However, an increase in Al composition leads to a decline in the lattice quality, thereby reducing the internal quantum efficiency (IQE). In addition, the light extraction efficiency (LEE) is limited due to the strong transverse magnetization polarization emission from the multiple quantum wells. Here, we designed the topological corner structure in AlGaN-MQWs, and the high electric field intensity in a tiny space at the corner results in an extremely high local density of optical states (LDOS), which could shorten the luminescence decay time of the emitter and increase the radiative rate by 26 times. Meanwhile, because the excited topological corner state resonance mode is a transverse-electric mode, enhancing only the transverse-electric luminescence without any gain for transverse-magnetic luminescence, thereby significantly improving the light extraction efficiency. Finally, according to theoretical calculations, the IQE could reach 68.75% at room temperature.

Nitrogen and Sulfur co-doped Carbon dots as an "on-off-on" Fluorescent Sensor for the Detection of Hg2+ and Ampicillin.

Herein, a fluorescent "on-off-on" nanosensor based on N,S-CDs was developed for highly precise and sensitive recognition of Hg2+ and ampicillin (AMP). Nitrogen and sulfur co-doped carbon dots with blue fluorescence were synthesized by one-pot hydrothermal method using ammonium citrate and DL-methionine as precursors. N,S-CDs exhibited a surface abundant in -OH, -COOH, and -NH2 groups, aiding in creating non-fluorescent ground state complexes when combined with Hg2+, leading to the suppression of N,S-CDs' fluorescence. Subsequent to additional AMP application, the mixed system's fluorescence was restored. Based on this N,S-CDs sensing system, the thresholds for detection for AMP and Hg2+ were discovered to be 0.121 µM and 0.493 µM, respectively. Furthermore, this methodology proved effective in identifying AMP in real samples of tap and lake water, yielding satisfactory results. Consequently, in the area of bioanalysis in intricate environmental sample work, the sensing system showed tremendous promise.

Non-enzymatic Detection of Uric Acid in Serum and Urine by Fluorescent and Visual Dual-Mode Sensor Based on 3-aminophenylboric Acid Functionalized Carbon Dots.

Herein, we developed a sophisticated dual-mode sensor that utilized 3-aminophenylboric acid functionalized carbon dots (APBA-CDs) to accurately detect uric acid (UA). Our innovative process involved synthesizing APBA-CDs that emitted at 369 nm using a one-step hydrothermal method with 3-aminophenylboric acid and L-glutamine as precursors, ethanol and deionized water as solvents. Once UA was introduced to the APBA-CDs, the fluorescence of the system became visibly quenched. The results of Zeta potential, Fourier transformed infrared (FTIR) spectra, fluorescence lifetime, and other characteristics were analyzed to determine that the reaction mechanism was static quenching. This meant that after UA was mixed with APBA-CDs, it combined with the boric acid function on the surface to form complexes, resulting in a decrease in fluorescence intensity and a blue shift in the absorption peak at about 295 nm in the Ultraviolet-visible (UV-vis) absorption spectra. We were pleased to report that we have successfully used the dual-reading platform to accurately detect UA in serum and human urine. It provided a superior quantitative and visual analysis of UA without the involvement of enzymes. We firmly believe that our innovative dual-mode sensor has immense potential in the fields of biosensing and health monitoring.

A nomogram based on clinical characteristics and nutritional indicators for relative and absolute weight loss during radiotherapy in initially inoperable patients with locally advanced esophageal squamous cell carcinoma.

OBJECTIVE: Radiation for locally advanced esophageal squamous cell carcinoma often is accompanied by radiation esophagitis, which interferes with oral intake. We aimed to develop a nomogram model to identify initially inoperable patients with relative and absolute weight loss who need prophylactic nutritional supplementation. METHODS: A total of 365 initially inoperable patients with locally advanced esophageal squamous cell carcinoma receiving radiotherapy between January 2018 and December 2022 were included in the study, which was divided into discovery and validation cohorts. Receiver operating characteristic and Kaplan-Meier curve analyses were performed to compare the areas under the curve and survival benefits. RESULTS: A total of 42.2% (154 of 365) of the patients had been diagnosed with cancer cachexia. The malnourished group had a higher interruption rate of radiotherapy and number of complication diseases (P < 0.05). Meanwhile, patients with malnutrition had lower lymphocytes and prognostic nutritional index (P < 0.05). The combined index showed a higher area under the curve value (0.67; P < 0.001) than number of complication diseases (area under the curve = 0.52) and prognostic nutritional index (area under the curve = 0.49) for relative weight loss (≥ 5%). Similarly, the combined index had a higher area under the curve value (0.79; P < 0.001) than number of complication diseases (area under the curve = 0.56), treatment regimens (area under the curve = 0.56), subcutaneous fat thickness (area under the curve = 0.60), pretreatment body weight (area under the curve = 0.61), neutrophils (area under the curve = 0.56), and prognostic nutritional index (area under the curve = 0.50) for absolute weight loss (≥ 5 kg). Absolute and relative weight loss remained independent prognostic factors, with short overall survival rates compared with the normal group (P < 0.05). Patients with high nomogram scores supported by nutritional intervention had less weight loss, better nutrition scores, and increased plasma CD8+ T cells, and interferon gamma. CONCLUSIONS: We developed a nomogram model that was intended to estimate relative and absolute weight loss in initially inoperable patients with locally advanced esophageal squamous cell carcinoma during radiotherapy, which might help facilitate an objective decision on prophylactic nutritional supplementation.

Investigation of the Application and Mechanism of Nitrogen and Phosphorus Co-doped Carbon Dots for Mercury Ion Detection.

In this paper, we obtained nitrogen and phosphorus co-doped carbon dots through a hydrothermal method using o-phenylenediamine and citric acid in a 40% phosphoric acid environment. The carbon dots emitted fluorescence at 476 nm under excitation at 408 nm and exhibited good selectivity and high sensitivity towards mercury ions. These carbon dots showed excellent dispersibility in water and maintained stable fluorescence even in high concentration salt environments. The interaction between mercury ions and functional groups on the carbon dots surface through electrostatic interaction resulted in static quenching. Simultaneously, by detecting the lifetime and transient absorption spectra of the carbon dots, we observed that the coordination of mercury ions with the carbon dots broadened the band structure of the carbon dots, and the existing photoinduced electron transfer process increased the non-radiative transition channel. The combined effect of dynamic quenching and static quenching significantly reduced the fluorescence intensity of the carbon dots at 476 nm. The carbon dots exhibited linear detection of mercury ions in the range of 0.01-1 µM, with a detection limit as low as 0.0245 µM. In terms of practical water environmental detection applications, these carbon dots were able to effectively detect mercury ions in tap water and lake water, demonstrating their broad application prospects in the field of environmental metal analysis.

How does workplace support promote postdoctoral career growth? A conservation of resources perspective.

Background: Postdoctoral researchers are critical to scholarly advancements, and promoting postdoctoral career growth is an endogenous path to help postdocs break through the "encircled city of scientific research". However, further research is needed to fully explore the mechanisms that connect workplace support to postdoctoral career growth. Methods: Drawing from the Conservation of Resources theory, this study proposes a chain mediation model that demonstrates how workplace support enhances career growth by connecting psychological capital with work-life balance. To understand the motivation and career growth of postdocs in China, we conducted two questionnaires in 2021 and 2023 with the support of relevant stations. Results: Analyzing 367 questionnaires from Chinese postdocs, our research indicates that workplace support has a positive impact on career growth. Additionally, both psychological capital and work-life balance are key factors that contribute to career growth, serving as separate mediators and as part of a chain of mediators. Discussion: This study validates the appropriateness of the Conservation of Resources theory in the study of the influence mechanism of postdoctoral career growth and proposes targeted strategies for academic institutions to improve support systems, promoting more effective career development pathways.

Epidermal and dermal cells from adult rat eccrine sweat gland-containing skin can reconstruct the three-dimensional structure of eccrine sweat glands.

BACKGROUND: Previously, we have demonstrated that eccrine sweat gland cells (ESGCs) can reconstruct the three-dimensional (3D) structure of eccrine sweat glands (ESGs). However, there is still a need to explore source cells capable of regenerating ESG to address the issue of ESG regeneration in ESGC-deficient conditions, such as severe burns. METHODS: The epidermal cells and dermal cells in adult rat ventral foot skin (ESG-bearing) were isolated. The isolated single epidermal cells and dermal cells were mixed with Matrigel, and then the mixture was implanted into the axillary/inguinal fat pads of nude mice. Five weeks after implantation, the Matrigel plugs were harvested and the morphology and differentiation of the cells were examined by H&E staining and fluorescent immunohistochemical staining for ESG markers, such as Na+ -K+ -2Cl- cotransporter 1 (NKCC1), Na+ -K+ -ATPase (NKA), Foxa1 and K14. RESULTS: The epidermal cells and dermal cells of adult rat ventral foot skin can reconstruct 3D structure and express specific markers of ESGs in skin, such as NKCC1, NKA and Foxa1, indicating the ESG-phenotypic differentiation of the 3D structures. Double immunofluorescence staining showed that some 3D structures expressed both the myoepithelial cell marker alpha-SMA and the common marker K14 of duct cells and myoepithelial cells, while some 3D structures expressed only K14, indicating that ESG-like 3D structures differentiated into duct-like and secretory coiled cells. CONCLUSION: Epidermal and dermal cells from adult ESG-bearing skin can be used as a cell source for ESG regeneration.

o-phenylenediamine Derived Fluorescent Carbon Quantum dots for Detection of Hg(II) in Environmental Water.

With the expansion of human activities, the consequent influx of mercury (Hg) into the food chain and the environment is seriously threatening human life. Herein, nitrogen and sulfur co-doped fluorescent carbon quantum dots (yCQDs) were prepared via a hydrothermal method using o-phenylenediamine (OPD) and taurine as precursors. The morphological characteristics as well as spectral features of yCQDs indicated that the photoluminescence mechanism should be the molecular state fluorophores of 2, 3-diaminophenothiazine (oxOPD), which is the oxide of OPD. The as-synthesized yCQDs exhibited sensitive recognition of Hg2+. According to the investigation in combination of UV-Vis absorption spectra, time-resolved fluorescence spectra and quantum chemical calculations, the abundant functional groups on the surface of yCQDs allowed Hg2+ to bind with yCQDs through various interactions, and the formed complexes significantly inhibited the absorption of excitation light, resulting in the static fluorescence quenching of yCQDs. The proposed yCQDs was utilized for Hg2+ sensing with the limit of detection calculated to be 4.50 × 10- 8 M. Furthermore, the recognition ability of yCQDs for Hg2+ was estimated in tap water, lake water and bottled water, and the results indicated that yCQDs have potential applications in monitoring Hg2+.

An "on-off-on" Fluorescent Sensor Based on Carbon Dots for the Detection of Au (III) and Creatinine.

The present study proposes a new approach for detecting trace amounts of creatinine (Cre) through the utilization of a fluorescence sensor system consisting of nitrogen doped carbon dots (NCDs) and gold ions (Au3+). Yellow fluorescent carbon dots were prepared using a one-step hydrothermal method with o-phenylenediamine and isopropanol as raw materials. First, gold ions are reduced to gold nanoparticles (Au NPs), which bind to NCDs, resulting in electron transfer and fluorescence quenching of NCDs. After adding creatinine, Cre and Au NPs were preferentially combined to form non-fluorescent complexes, and the NCDs fluorescence was restored. The study achieved a detection limit of 1.06 × 10-7 M for Au3+ and 9.29 × 10-9 M for creatinine, indicating a high level of sensitivity. The sensing system has also been successfully utilized for detecting Au3+ in lake water and Cre in human urine, indicating its promising potential and practical applications in the areas of environmental monitoring and biosensing.

Effect of chemotherapy alone or combined with immunotherapy for locally advanced or metastatic genitourinary small cell carcinoma: a real-world retrospective study.

BACKGROUND: Genitourinary small cell carcinoma is rare, and has a poor prognosis. However, effective treatment options for this disease are limited. We present a study to assess the efficacy of chemotherapy alone or combined with immunotherapy for locally advanced or metastatic genitourinary small cell carcinoma (GSCC). METHODS: We performed a retrospective analysis of patients with locally advanced or metastatic GSCC from Jan 2013 to September 2022 at Sun Yat-sen University Cancer Center. The survival and safety profiles were analyzed. RESULTS: Forty-two GSCC patients were enrolled, which included 20 with chemotherapy plus immunotherapy and 22 with chemotherapy alone. The median follow-up time was 15.13 months (95% CI, 8.84-21.42). The addition of immunotherapy to chemotherapy demonstrated no significant difference in median progression-free survival (p = 0.37). However, the median overall survival (OS) was 22.97 and 14.03 months with immunotherapy plus chemotherapy and chemotherapy alone, respectively (HR = 0.69, 95%CI 0.08-0.55, p = 0.017). Two patients with immunotherapy plus chemotherapy achieved clinical complete remission. The overall response rate for patients receiving chemotherapy combined with immunotherapy was 65%, which was higher in comparison to those treated with chemotherapy alone (50%). Univariate and multivariate analyses demonstrated that chemotherapy combined with immunotherapy independently achieved favorable OS. Four patients experienced immunotherapy-related adverse events, with one developing grade 3 hypothyroidism. CONCLUSIONS: Among patients with locally advanced or metastatic GSCC, immunotherapy combined with chemotherapy might be thought of as a potentially effective treatment option for patients with GSCC.

Precise Correction of Lhcgr Mutation in Stem Leydig Cells by Prime Editing Rescues Hereditary Primary Hypogonadism in Mice.

Hereditary primary hypogonadism (HPH), caused by gene mutation related to testosterone synthesis in Leydig cells, usually impairs male sexual development and spermatogenesis. Genetically corrected stem Leydig cells (SLCs) transplantation may provide a new approach for treating HPH. Here, a novel nonsense-point-mutation mouse model (LhcgrW495X ) is first generated based on a gene mutation relative to HPH patients. To verify the efficacy and feasibility of SLCs transplantation in treating HPH, wild-type SLCs are transplanted into LhcgrW495X mice, in which SLCs obviously rescue HPH phenotypes. Through comparing several editing strategies, optimized PE2 protein (PEmax) system is identified as an efficient and precise approach to correct the pathogenic point mutation in Lhcgr. Furthermore, delivering intein-split PEmax system via lentivirus successfully corrects the mutation in SLCs from LhcgrW495X mice ex vivo. Gene-corrected SLCs from LhcgrW495X mice exert ability to differentiate into functional Leydig cells in vitro. Notably, the transplantation of gene-corrected SLCs effectively regenerates Leydig cells, recovers testosterone production, restarts sexual development, rescues spermatogenesis, and produces fertile offspring in LhcgrW495X mice. Altogether, these results suggest that PE-based gene editing in SLCs ex vivo is a promising strategy for HPH therapy and is potentially leveraged to address more hereditary diseases in reproductive system.

Statistical learning and children's emergent literacy in rural Côte d'Ivoire.

Studies of non-linguistic statistical learning (SL) have often linked performance in SL tasks with differences in language outcomes. Most of these studies have focused on Western and high-income educational contexts, but children worldwide learn in radically different educational systems and communities, and often in a second language. In the west African nation of Côte d'Ivoire, children enter fifth grade (CM-1) with widely varying ages and literacy skills. Across three iteratively-developed experiments, 157 children, age 8-15 years, in rural communities in the greater-Adzópe region of Côte d'Ivoire watched sequences of cartoon images with embedded triplet patterns on touchscreen tablets, while performing a target-detection task. We assessed these tablet-based adaptations of non-linguistic visual SL and asked whether the children's individual differences in performance on the SL tasks were related to their first and second language and literacy skills. We found group-level evidence that children used the statistical regularities in the image sequence to gradually decrease their response times, but their responses on post-test discrimination did not reflect this learning. When evaluating the correlation between SL and language skills, individual differences related to other task demands predicted oral language skills shared by first and second languages, while SL better predicted second language print skills. These findings suggest that non-linguistic SL paradigms can measure similar skills in Ivorian children as previous samples, but they also echo recent calls for further cross-cultural validation, greater internal reliability, and tests for confounding variables (such as processing speed) in studies of individual differences in statistical learning. RESEARCH HIGHLIGHTS: We iteratively adapted three visual statistical learning studies for children in rural Côte d'Ivoire. Group-level analyses indicates that the children learn the underlying statistical regularities. Individual-differences analyses reveal some evidence that the statistical learning measure is also correlated with task demands that may be driven by cross-cultural differences. Like previous research, statistical learning is correlated with second language literacy, but we did not find a relationship between SL and oral language skills in first and second languages.

Joint Encryption Model Based on a Randomized Autoencoder Neural Network and Coupled Chaos Mapping.

Following an in-depth analysis of one-dimensional chaos, a randomized selective autoencoder neural network (AENN), and coupled chaotic mapping are proposed to address the short period and low complexity of one-dimensional chaos. An improved method is proposed for synchronizing keys during the transmission of one-time pad encryption, which can greatly reduce the usage of channel resources. Then, a joint encryption model based on randomized AENN and a new chaotic coupling mapping is proposed. The performance analysis concludes that the encryption model possesses a huge key space and high sensitivity, and achieves the effect of one-time pad encryption. Experimental results show that this model is a high-security joint encryption model that saves secure channel resources and has the ability to resist common attacks, such as exhaustive attacks, selective plaintext attacks, and statistical attacks.

The influence of Big Five personality traits on college students' key competencies: the mediating effect of psychological capital.

Background: In recent years, both society and employers have put forward higher requirements for the comprehensive quality of college students in the new era. Based on the conservation of resources theory and life-cycle approach, this study aimed to examine the relationship between the Big Five personality traits, the psychological capital, and the key competencies among college students and analyzed the mediating role of the psychological capital in this link. Methods: A total of 1,132 Chinese undergraduates (67.40% girls; 48.67% from key universities) participated. Participants completed self-report questionnaires that evaluated the five key characteristics of personality, psychological capital, and key competencies. Results: There were extremely significant university-type differences in key competencies of college students. And the mediating role of psychological capital in the link between Big Five personality traits and key competencies was validated according to PROCESS model 4. Psychological capital serves as a partial mediator in the relationships between neuroticism and critical thinking, openness and creativity, conscientiousness and creativity, openness and communication, conscientiousness and communication, extraversion and collaboration, as well as openness and collaboration. The proportion of mediating effects for the above models was 5.97, 10.89, 11.82, 12.24, 11.98, 12.39, and 22.72%, respectively. Discussion: The findings provide a better understanding of the key competencies of college students from the perspectives of the Big Five personality traits and psychological capital and suggest a greater emphasis to focusing on personality and improving psychological capital.

[Impact of Climate Change on Summer Ozone in China].

Meteorological conditions have important impacts on surface ozone (O3) formation. To evaluate the influence of future climate change on O3 concentrations in different regions of China, this study employed the climate data from the community earth system model provided by the CMIP5 under the RCP4.5, RCP6.0, and RCP8.5 scenarios to generate the initial and boundary conditions for the WRF model. Then, the dynamic downscaling WRF results were fed into a CMAQ model as meteorological fields with fixed emission data. Two 10-year periods (2006-2015 and 2046-2055) were selected in this study to discuss the impacts of climate change on O3. The results showed that climate change increased boundary layer height, mean temperature, and heatwave days in China during summer. Relative humidity decreased and wind speed near the surface showed no obvious change in the future. O3 concentration showed an increasing trend in Beijing-Tianjin-Hebei, Sichuan Basin, and South China. The extreme value of O3 maximum daily 8-hour moving average (MDA8) showed an increasing trend, following the order of RCP8.5 (0.7 µg·m-3)>RCP6.0 (0.3 µg·m-3)>RCP4.5 (0.2 µg·m-3). The number of days exceeding the standard for summer O3 had a similar spatial distribution with the heatwave days in China. The increase in heatwave days led to the increase in O3 extreme pollution events, and the possibility of a long-lasting O3 pollution event will increase in China in the future.

Dissociation Between Linguistic and Nonlinguistic Statistical Learning in Children with Autism.

Statistical learning (SL), the ability to detect and extract regularities from inputs, is considered a domain-general building block for typical language development. We compared 55 verbal children with autism (ASD, 6-12 years) and 50 typically-developing children in four SL tasks. The ASD group exhibited reduced learning in the linguistic SL tasks (syllable and letter), but showed intact learning for the nonlinguistic SL tasks (tone and image). In the ASD group, better linguistic SL was associated with higher language skills measured by parental report and sentence recall. Therefore, the atypicality of SL in autism is not domain-general but tied to specific processing constraints related to verbal stimuli. Our findings provide a novel perspective for understanding language heterogeneity in autism.

Nitrogen-doped carbon dots with bright fluorescence for highly sensitive detection of Fe3+ in environmental waters.

In this study, we synthesized stable nitrogen-doped carbon dots by a simple and economical one-step hydrothermal method using l-cysteine and anhydrous ethylenediamine as precursors. The prepared carbon dots have bright and stable blue light emission near 383 nm and can be used as fluorescent probes to detect the concentration of Fe3+ in environmental waters. It was demonstrated that due to intermolecular electrostatic interaction, a non-fluorescent complex N-CDs/Fe3+ is formed by coordination of Fe3+ with amino and carboxyl functional groups on the surface of carbon dots. Therefore, in combination with internal filtration effect, the fluorescence of carbon dots can be quenched in the presence of Fe3+, and the degree of quenching is linearly related to the concentration of Fe3+. The limit of detection in deionized water was as low as 0.069 µM with R2 of 0.998 and a linear range of 0.3 to 20 µM. In addition, satisfactory recoveries were achieved for the determination of Fe3+ in environmental water samples. The method is reliable, with highly sensitivity and selectivity, and has potential for practical applications in environmental metal analysis.

Progress in Targeted Mass Spectrometry (Parallel Accumulation-Serial Fragmentation) and Its Application in Plasma/Serum Proteomics.

Targeted mass spectrometry using multiple reaction monitoring (MRM) or parallel reaction monitoring (PRM) has been commonly used for protein biomarker validation in plasma, serum, or other clinically relevant specimens due to its high specificity, selectivity, and multiplexing capability compared with immunoassays. As the emerging mode termed parallel accumulation-serial fragmentation (prmPASEF) significantly improved analyte throughput (100-1000), sensitivity (attomole level), and acquisition speed, it promises to broaden the application of targeted mass spectrometry to simultaneous biomarker discovery and validation with high accuracy. Here, we summarize the general approach of the MRM and PRM techniques used for serum/plasma proteomics and describe a detailed step-by-step procedure for the development of MRM/PRM assays for secreted proteins.