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Background Severe vitamin D deficiency (SVDD) dramatically increases the risks of mortality, infections, and many other diseases. Studies have reported higher prevalence of vitamin D deficiency in patients with critical illness than general population. This multicenter retrospective cohort study develops and validates a score-based model for predicting SVDD in patients with critical illness. Methods A total of 662 patients with critical illness were enrolled between October 2017 and July 2020. SVDD was defined as a serum 25(OH)D level of < 12 ng/mL (or 30 nmol/L). The data were divided into a derivation cohort and a validation cohort on the basis of date of enrollment. Multivariable logistic regression (MLR) was performed on the derivation cohort to generate a predictive model for SVDD. Additionally, a score-based calculator (the SVDD score) was designed on the basis of the MLR model. The model’s performance and calibration were tested using the validation cohort. Results The prevalence of SVDD was 16.3% and 21.7% in the derivation and validation cohorts, respectively. The MLR model consisted of eight predictors that were then included in the SVDD score. The SVDD score had an area under the receiver operating characteristic curve of 0.848 [95% confidence interval (CI) 0.781–0.914] and an area under the precision recall curve of 0.619 (95% CI 0.577–0.669) in the validation cohort. Conclusions This study developed a simple score-based model for predicting SVDD in patients with critical illness. Trial registration: ClinicalTrials.gov protocol registration ID: NCT03639584. Date of registration: May 12, 2022. Graphical Abstract

In this paper, we studied the wire bonding ability and the solder joint reliability for Electrolytic Ni/Au and ENEPIG. For studying wire bonding ability, 4N wire with 20um in diameter was used. Pull strength of Au wire and failure mode after each pull test were both the criteria of wire bonding. After wire pull test, the pull strength and failure mode of Electrolytic Ni/Au and ENEPIG were similar. Therefore, it could be supposed the wire bonding ability of ENEPIG is similar with Electrolytic Ni/Au. For solder joint reliability, different types of solder joint test were conductedconventional ball shear test, cold-ball pull test. High speed ball shear test was also applied to simulate high strain rate loading, similar as drop test. Failure mode and micro analysis were carried out by the analytical tools, including Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDX).In addition, samples were performed thermal process, like multi reflow (as-soldering, 3x, 6x) and solid aging (duration: 250, 500, 1000 hours at 150 0 C). Interfacial reaction of two type surface finish with solder ball, Sn96.5Ag3Cu0.5 (SAC305), were observed by SEM for different thermal process. Cross section image and morphology image were observed to study IMC appearance. And EDX was also used to confirm the IMC phase From the ball shear test results, it was no obvious difference after multi reflow times and different solid aging duration for Electrolytic Ni/Au and ENEPIG. The failure mode of Electrolytic Ni/Au and ENEPIG were both broken at solder. Cold-ball pull test showed Electrolytic Ni/Au and ENEPIG have similarly failure mode distribution after multi reflow process and solid aging process. In the high speed ball shear test, the behavior of broken interface was quite different between Electrolytic Ni/Au and ENEPIG. For as-soldering samples, the broken interface of Electrolytic Ni/Au usually happened at intermetallic compound (IMC) phase, but the ENEPIG usually happened at solder phase. Besides, samples are tested with different test speed to observed the transition point of failure mode that from ductile to brittle. The results showed the transition point of Electrolytic Ni/Au was prior to ENEPIG. On the other hand, the high speed shear test results of ENEPIG after performing solid aging showed lower IMCbroken percentage than Electrolytic Ni/Au. It could be deduced that ENEPIG has better solder joint quality.