Mortality prediction and influencing factors for intensive care unit patients with acute tubular necrosis: random survival forest and cox regression analysis.

Background: Patients with acute tubular necrosis (ATN) not only have severe renal failure, but also have many comorbidities, which can be life-threatening and require timely treatment. Identifying the influencing factors of ATN and taking appropriate interventions can effectively shorten the duration of the disease to reduce mortality and improve patient prognosis. Methods: Mortality prediction models were constructed by using the random survival forest (RSF) algorithm and the Cox regression. Next, the performance of both models was assessed by the out-of-bag (OOB) error rate, the integrated brier score, the prediction error curve, and area under the curve (AUC) at 30, 60 and 90 days. Finally, the optimal prediction model was selected and the decision curve analysis and nomogram were established. Results: RSF model was constructed under the optimal combination of parameters (mtry = 10, nodesize = 88). Vasopressors, international normalized ratio (INR)_min, chloride_max, base excess_min, bicarbonate_max, anion gap_min, and metastatic solid tumor were identified as risk factors that had strong influence on mortality in ATN patients. Uni-variate and multivariate regression analyses were used to establish the Cox regression model. Nor-epinephrine, vasopressors, INR_min, severe liver disease, and metastatic solid tumor were identified as important risk factors. The discrimination and calibration ability of both predictive models were demonstrated by the OOB error rate and the integrated brier score. However, the prediction error curve of Cox regression model was consistently lower than that of RSF model, indicating that Cox regression model was more stable and reliable. Then, Cox regression model was also more accurate in predicting mortality of ATN patients based on the AUC at different time points (30, 60 and 90 days). The analysis of decision curve analysis shows that the net benefit range of Cox regression model at different time points is large, indicating that the model has good clinical effectiveness. Finally, a nomogram predicting the risk of death was created based on Cox model. Conclusion: The Cox regression model is superior to the RSF algorithm model in predicting mortality of patients with ATN. Moreover, the model has certain clinical utility, which can provide clinicians with some reference basis in the treatment of ATN and contribute to improve patient prognosis.

Occurrence and Exposure Assessment of Nickel in Zhejiang Province, China.

Nickel (Ni) is a silver-white metal with high antioxidative properties, often existing in a bivalent form in the environment. Despite being the fifth most abundant metal on Earth, anthropogenic activities, including industrial processes, have elevated Ni levels in environmental media. This study investigated Ni contamination in various food groups in Zhejiang Province, China, mainly focusing on Ni levels in beans, vegetables, aquatic foods, meat products, cereal products, and fruits. A total of 2628 samples were collected and analyzed. Beans exhibited the highest Ni content in all samples. The overall detection rate of Ni was 86.5%, with variation among food categories. For plant-origin foods, legumes had the highest Ni concentration while for animal-origin foods, shellfish showed the highest median Ni concentration. The results indicate generally acceptable Ni exposure levels among Zhejiang residents, except for children aged 0-6. Beans were identified as the primary contributor to high Ni exposure risk. The paper suggests monitoring Ni contamination in food, especially for vulnerable populations, and provides insights into exposure risks in different age groups.

Quadratic convergence of monotone iterates for semilinear elliptic obstacle problems.

In this paper, we consider the numerical solution for the discretization of semilinear elliptic complementarity problems. A monotone algorithm is established based on the upper and lower solutions of the problem. It is proved that iterates, generated by the algorithm, are a pair of upper and lower solution iterates and converge monotonically from above and below, respectively, to the solution of the problem. Moreover, we investigate the convergence rate for the monotone algorithm and prove quadratic convergence of the algorithm. The monotone and quadratic convergence results are also extended to the discrete problems of the two-sided obstacle problems with a semilinear elliptic operator. We also present some simple numerical experiments.

A novel strategy to assemble achiral ligands to chiral helical polyrotaxane structures.

Using the achiral N,N'-bis(2-pyridylmethyl)-1,6-hexanediamine ligand bearing two end pyridyl groups as the source of conformational chirality, a novel type of TMeQ[6]-based helical polyrotaxane was prepared and characterized by X-ray crystallography and (1)H NMR spectroscopy. The chirality of the polyrotaxane was generated from twisting of the hexylidene of the N,N'-bis(2-pyridylmethyl)-1,6-hexanediamine "string" when bound within the hydrophobic cavity of TMeQ[6]. Two opposite chiral helical polyrotaxanes crystallize as a racemic compound.

2,2'-(Heptane-1,7-di-yl)dibenz-imidazo-lium chloride nitrate monohydrate.

In the title compound, C(21)H(26)N(4) (2+)·Cl(-)·NO(3) (-)·H(2)O, the organic cations, anions and water mol-ecules are linked through N-H⋯Cl, N-H⋯O, N-H⋯N and O-H⋯Cl hydrogen bonds, forming a three-dimensional framework, assisted by C-H⋯π inter-actions.

Structure of supramolecular assemblies formed by alpha,delta-tetramethylcucurbit[6]uril and 4-nitrophenol.

A host-guest assembly, [(C(40)H(44)N(24)O(12)).(C(6)H(5)NO(3))(8).13(H(2)O)] (1), based on a partial substituted cucurbituril, alpha,delta-tetramethylcucurbit[6]uril (TMeQ[6]), and 4-nitrophenol was synthesized and structurally characterized by single-crystal X-ray diffraction. A combination of hydrogen-bonding between the latticed water molecule and the hydroxyl group of 4-nitrophenol, the hydroxyl group of 4-nitrophenol and the carbonyl groups lining the portals in additon, the C-H...pi interactions between the 4-nitrophenol molecules could be the driving forces of formation such an exclusion host-guest assembly.

4-[3-(4-Nitro-phen-oxy)prop-oxy]aniline.

The mol-ecules of the title compound, C(15)H(16)N(2)O(4), are linked via N-H⋯O hydrogen bonds, forming undulating one-dimensional chains. Adjacent chains are linked by weak C-H⋯π inter-actions, forming a three-dimensional network.