Publications by authors named "Cheng-Wei Huang"

18 Publications

  • Page 1 of 1

Multisystem Inflammatory Syndrome after SARS-CoV-2 Infection and COVID-19 Vaccination.

Emerg Infect Dis 2021 May 25;27(7). Epub 2021 May 25.

We report 3 patients in California, USA, who experienced multisystem inflammatory syndrome (MIS) after immunization and severe acute respiratory syndrome coronavirus 2 infection. During the same period, 3 adults who were not vaccinated had MIS develop at a time when ≈7% of the adult patient population had received >1 vaccine.
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http://dx.doi.org/10.3201/eid2707.210594DOI Listing
May 2021

Characteristics of patients discharged and readmitted after COVID-19 hospitalisation within a large integrated health system in the United States.

Infect Dis (Lond) 2021 May 8:1-5. Epub 2021 May 8.

Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, CA, USA.

Background: Limited studies have explored post-discharge outcomes following Coronavirus Disease 2019 (COVID-19) hospitalisation. We sought to characterise patients discharged following a COVID-19 hospitalisation within a large integrated health system in the United States.

Methods: We performed a retrospective study of 2180 COVID-19 patients discharged between 1 April 2020 and 31 July 2020. The primary endpoint was all-cause observation stay or inpatient readmission within 30 days from discharge. Bivariate and multivariable logistic regression analyses were performed to estimate the association between key socio-demographic and clinical characteristics with risk of 30-day readmission.

Results: The 30-day readmission rate was 7.6% ( = 166); 30-day mortality rate was 1% ( = 19). Most readmissions were respiratory-related (58%) and occurred at a median time of 5 days post discharge. Adjusted models showed that prior hospitalisations (Odds Ratio = 2.36, [95% Confidence Interval: 1.59-3.50]), chronic pulmonary disease (1.57 [1.09-2.28]), and discharge to home health (1.46 [1.01-2.11]) were significantly associated with 30-day readmission. Longer duration from diagnosis to index admission was borderline associated with lower odds of readmission (0.95 [0.91-1.00]).

Conclusion: Readmission and mortality rates for COVID-19 following discharge are low. Most readmissions occur early and are due to respiratory causes and may reflect the prolonged acute disease course.
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http://dx.doi.org/10.1080/23744235.2021.1924398DOI Listing
May 2021

MLL3 suppresses tumorigenesis through regulating TNS3 enhancer activity.

Cell Death Dis 2021 Apr 6;12(4):364. Epub 2021 Apr 6.

Frontier Science Center for Immunology and Metabolism, Wuhan University, Wuhan, Hubei, 430072, China.

MLL3 is a histone H3K4 methyltransferase that is frequently mutated in cancer, but the underlying molecular mechanisms remain elusive. Here, we found that MLL3 depletion by CRISPR/sgRNA significantly enhanced cell migration, but did not elevate the proliferation rate of cancer cells. Through RNA-Seq and ChIP-Seq approaches, we identified TNS3 as the potential target gene for MLL3. MLL3 depletion caused downregulation of H3K4me1 and H3K27ac on an enhancer ~ 7 kb ahead of TNS3. 3C assay indicated the identified enhancer interacts with TNS3 promoter and repression of enhancer activity by dCas9-KRAB system impaired TNS3 expression. Exogenous expression of TNS3 in MLL3 deficient cells completely blocked the enhanced cell migration phenotype. Taken together, our study revealed a novel mechanism for MLL3 in suppressing cancer, which may provide novel targets for diagnosis or drug development.
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http://dx.doi.org/10.1038/s41419-021-03647-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8024252PMC
April 2021

COVID-19 and Survival in Maintenance Dialysis.

Kidney Med 2021 Jan-Feb;3(1):132-135. Epub 2020 Nov 24.

Department of Research and Evaluation, Kaiser Permanente Southern California, Pasadena, CA.

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http://dx.doi.org/10.1016/j.xkme.2020.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7685033PMC
November 2020

Soluble Dipeptidyl Peptidase-4 Induces Fibroblast Activation Through Proteinase-Activated Receptor-2.

Front Pharmacol 2020 30;11:552818. Epub 2020 Sep 30.

Department of Life Science, Fu Jen Catholic University, New Taipei City, Taiwan.

Fibroblasts are the chief secretory cells of the extracellular matrix (ECM) responsible for basal deposition and degradation of the ECM under normal conditions. During stress, fibroblasts undergo continuous activation, which is defined as the differentiation of fibroblasts into myofibroblasts, a cell type with an elevated capacity for secreting ECM proteins. Dipeptidyl peptidase-4 (DPP4) is a ubiquitously expressed transmembrane glycoprotein and exerts effects that are both dependent and independent of its enzymatic activity. DPP4 has been demonstrated to define fibroblast populations in human skin biopsies of systemic sclerosis. Shedding of DPP4 from different tissues into the circulation appears to be involved in the pathogenesis of the diseases. The mechanism underlying soluble DPP4-induced dermal fibrosis has not been clearly determined. The effects of DPP4 on murine 3T3 fibroblasts and human dermal fibroblasts were evaluated by measuring the expression of fibrotic proteins, such as α-SMA and collagen. Soluble DPP4 stimulated the activation of fibroblasts in a dose-dependent manner by activating nuclear factor-kappa B (NF-κB) and suppressor of mothers against decapentaplegic (SMAD) signaling. Blocking proteinase-activated receptor-2 (PAR2) abrogated the DPP4-induced activation of NF-κB and SMAD and expression of fibrosis-associated proteins in fibroblasts. Linagliptin, a clinically available DPP4 inhibitor, was observed to abrogate the soluble DPP4-induced expression of fibrotic proteins. This study demonstrated the mechanism underlying soluble DPP4, which activated NF-κB and SMAD signaling through PAR2, leading to fibroblast activation. Our data extend the current view of soluble DPP4. Elevated levels of circulating soluble DPP4 may contribute to one of the mediators that induce dermal fibrosis in patients.
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http://dx.doi.org/10.3389/fphar.2020.552818DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7561399PMC
September 2020

Association between hypothyroidism and chronic kidney disease observed among an adult population 55 years and older.

Medicine (Baltimore) 2020 Apr;99(17):e19569

Division of Nephrology and Hypertension, Kaiser Permanente Los Angeles Medical Center, Los Angeles, California.

Hypothyroidism and chronic kidney disease (CKD) are highly prevalent conditions with a potential mechanistic link. We sought to determine whether hypothyroidism is associated with CKD among a large diverse community-based cohort.A cross-sectional study was performed (January 1, 1990-December 31, 2017) within a large integrated health system. Individuals age ≥55 years of age with outpatient measurements of thyroid stimulating hormone (TSH) and ≥2 serum creatinine values were included. Hypothyroidism was defined as TSH >4 mIU/L and/or receipt of thyroid hormone replacement and further categorized as hypothyroid status: TSH >4 mcIU/mL and attenuated-hypothyroid status: TSH <4 mcIU/mL with receipt of thyroid hormone replacement. Euthyroidism was defined as TSH <4 mIU/L and no thyroid hormone replacement. Our primary measure was CKD defined as an estimated glomerular filtration rate (eGFR) <45 mL/min/1.73 m. Multivariable logistic regression adjusting for age, sex, race, and comorbidities was used to estimate odds ratios (OR) for CKD by thyroid status.Among 378,101 individuals, 114,872 (30.4%) had hypothyroidism among whom 31,242 and 83,630 had hypothyroid and attenuated-hypothyroid statuses, respectively. Individuals with hypothyroidism had a CKD OR (95%CI) of 1.25 (1.21-1.29) compared with those with euthyroidism. Granular examination of thyroid statuses showed that hypothyroid and attenuated-hypothyroid statuses had CKD ORs (95% CI) of 1.59 (1.52-1.66) and 1.12 (1.08-1.16), respectively. A similar relationship was observed in analyses that defined CKD as an eGFR <60 L/min/1.73 m.Among individuals 55 years and older, we observed that those with hypothyroidism were more likely to have CKD. A stronger association was found among patients of hypothyroid status compared with attenuated-hypothyroid status suggesting a dose dependent relationship.
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http://dx.doi.org/10.1097/MD.0000000000019569DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7220776PMC
April 2020

Frequency-domain CBE imaging for ultrasound localization of the HIFU focal spot: a feasibility study.

Sci Rep 2020 03 25;10(1):5468. Epub 2020 Mar 25.

Department of Medical Imaging and Radiological Sciences, College of Medicine, Chang Gung University, Taoyuan, Taiwan.

High-intensity focused ultrasound (HIFU) is a well-accepted tool for noninvasive thermal therapy. To control the quality of HIFU treatment, the focal spot generated in tissues must be localized. Ultrasound imaging can monitor heated regions; in particular, the change in backscattered energy (CBE) allows parametric imaging to visualize thermal information in the tissue. Conventional CBE imaging constructed in the spatial domain may be easily affected by noises when the HIFU focal spot is visualized. This study proposes frequency-domain CBE imaging to improve noise tolerance and image contrast in HIFU focal spot monitoring. Phantom experiments were performed in a temperature-controlled environment. HIFU of 2.12 MHz was applied to the phantoms, during which a clinical scanner equipped with a 3-MHz convex array transducer was used to collect raw image data consisting of backscattered signals for B-mode, spatial-, and frequency-domain CBE imaging. Concurrently, temperature changes were measured at the focal spot using a thermocouple for comparison with CBE values by calculating the correlation coefficient r. To further analyze CBE image contrast levels, a contrast factor was introduced, and an independent t-test was performed to calculate the probability value p. Experimental results showed that frequency-domain CBE imaging performed well in thermal distribution visualization, enabling quantitative detection of temperature changes. The CBE value calculated in the frequency domain also correlated strongly with that obtained using the conventional spatial-domain approach (r = 0.97). In particular, compared with the image obtained through the conventional method, the contrast of the CBE image obtained using the method based on frequency-domain analysis increased by 2.5-fold (4 dB; p < 0.05). Frequency-domain computations may constitute a new strategy when ultrasound CBE imaging is used to localize the focal spot in HIFU treatment planning.
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http://dx.doi.org/10.1038/s41598-020-62363-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7096526PMC
March 2020

Mechanisms for minimizing height-related stomatal conductance declines in tall vines.

Plant Cell Environ 2019 11 28;42(11):3121-3139. Epub 2019 Jun 28.

Nicholas School of the Environment, Duke University, Durham, North Carolina, 27708.

The ability to transport water through tall stems hydraulically limits stomatal conductance (g ), thereby constraining photosynthesis and growth. However, some plants are able to minimize this height-related decrease in g , regardless of path length. We hypothesized that kudzu (Pueraria lobata) prevents strong declines in g with height through appreciable structural and hydraulic compensative alterations. We observed only a 12% decline in maximum g along 15-m-long stems and were able to model this empirical trend. Increasing resistance with transport distance was not compensated by increasing sapwood-to-leaf-area ratio. Compensating for increasing leaf area by adjusting the driving force would require water potential reaching -1.9 MPa, far below the wilting point (-1.2 MPa). The negative effect of stem length was compensated for by decreasing petiole hydraulic resistance and by increasing stem sapwood area and water storage, with capacitive discharge representing 8-12% of the water flux. In addition, large lateral (petiole, leaves) relative to axial hydraulic resistance helped improve water flow distribution to top leaves. These results indicate that g of distal leaves can be similar to that of basal leaves, provided that resistance is highest in petioles, and sufficient amounts of water storage can be used to subsidize the transpiration stream.
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http://dx.doi.org/10.1111/pce.13593DOI Listing
November 2019

A network model links wood anatomy to xylem tissue hydraulic behaviour and vulnerability to cavitation.

Plant Cell Environ 2018 12 17;41(12):2718-2730. Epub 2018 Sep 17.

Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.

Plant xylem response to drought is routinely represented by a vulnerability curve (VC). Despite the significance of VCs, the connection between anatomy and tissue-level hydraulic response to drought remains a subject of inquiry. We present a numerical model of water flow in flowering plant xylem that combines current knowledge on diffuse-porous anatomy and embolism spread to explore this connection. The model produces xylem networks and uses different parameterizations of intervessel connection vulnerability to embolism spread: the Young-Laplace equation and pit membrane stretching. Its purpose is upscaling processes occurring on the microscopic length scales, such as embolism propagation through pit membranes, to obtain tissue-scale hydraulics. The terminal branch VC of Acer glabrum was successfully reproduced relying only on real observations of xylem tissue anatomy. A sensitivity analysis shows that hydraulic performance and VC shape and location along the water tension axis are heavily dependent on anatomy. The main result is that the linkage between pit-scale and vessel-scale anatomical characters, along with xylem network topology, affects VCs significantly. This work underscores the importance of stepping up research related to the three-dimensional network structure of xylem tissues. The proposed model's versatility makes it an important tool to explore similar future questions.
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http://dx.doi.org/10.1111/pce.13415DOI Listing
December 2018

Outcome of Gamma Knife radiosurgery for trigeminal neuralgia associated with neurovascular compression.

J Clin Neurosci 2018 Jan 23;47:174-177. Epub 2017 Oct 23.

Gamma Knife Center, Chang Bing Show Chwan Memorial Hospital, No. 6-1, Lugong Rd., Lukang Township, Changhua County 505, Taiwan. Electronic address:

We reviewed 130 patients from 1999 to 2012 to evaluate whether neurovascular compression (NVC) has prognostic value for pain relief in idiopathic trigeminal neuralgia (TN) treated by Gamma Knife radiosurgery (GKRS). Patients were assigned to one of the following groups based on NVC identified by MRI: no NVC, small vessel NVC, and large vessel (defined as part of the vertebrobasilar arterial system) NVC. Follow-up ranged from 4 to 14years. Primary outcome was pain graded by the Barrow Neurological Institute (BNI) pain scale. Successful pain control was defined asa score within Grade I-IIIb. Among the 130 patients, 53 had no neurovascular compression (group 1), 60 had a small vessel NVC (group 2), and 17 had a large vessel NVC (group 3). Successful pain control was 85% in group 1, 75% in group 2, and 88% in group 3 (X=2.480, p=.289). Secondary outcome was new onset facial numbness which was 21% in group 1, 28% in group 2, and 35% in group 3 (X=1.683, p=.431). NVC did not affect pain outcome for TN patients treated by GKRS. The lack of poorer response with large vessel NVC that has been reported in literature may be explained by treatment of multiple 4mm shots (as opposed to a single shot in 11/17 patients) to cover a larger compression area of the nerve root by a tortuous vessel.
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http://dx.doi.org/10.1016/j.jocn.2017.09.016DOI Listing
January 2018

Increasing atmospheric humidity and CO concentration alleviate forest mortality risk.

Proc Natl Acad Sci U S A 2017 09 28;114(37):9918-9923. Epub 2017 Aug 28.

Department of Civil and Environmental Engineering, Duke University, Durham, NC 27708.

Climate-induced forest mortality is being increasingly observed throughout the globe. Alarmingly, it is expected to exacerbate under climate change due to shifting precipitation patterns and rising air temperature. However, the impact of concomitant changes in atmospheric humidity and CO concentration through their influence on stomatal kinetics remains a subject of debate and inquiry. By using a dynamic soil-plant-atmosphere model, mortality risks associated with hydraulic failure and stomatal closure for 13 temperate and tropical forest biomes across the globe are analyzed. The mortality risk is evaluated in response to both individual and combined changes in precipitation amounts and their seasonal distribution, mean air temperature, specific humidity, and atmospheric CO concentration. Model results show that the risk is predicted to significantly increase due to changes in precipitation and air temperature regime for the period 2050-2069. However, this increase may largely get alleviated by concurrent increases in atmospheric specific humidity and CO concentration. The increase in mortality risk is expected to be higher for needleleaf forests than for broadleaf forests, as a result of disparity in hydraulic traits. These findings will facilitate decisions about intervention and management of different forest types under changing climate.
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http://dx.doi.org/10.1073/pnas.1704811114DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5604008PMC
September 2017

Gamma Knife radiosurgery for large vestibular schwannomas greater than 3 cm in diameter.

J Neurosurg 2018 05 14;128(5):1380-1387. Epub 2017 Jul 14.

1Gamma Knife Center, Chang Bing Show Chwan Memorial Hospital.

OBJECTIVE Stereotactic radiosurgery (SRS) is an important alternative management option for patients with small- and medium-sized vestibular schwannomas (VSs). Its use in the treatment of large tumors, however, is still being debated. The authors reviewed their recent experience to assess the potential role of SRS in larger-sized VSs. METHODS Between 2000 and 2014, 35 patients with large VSs, defined as having both a single dimension > 3 cm and a volume > 10 cm, underwent Gamma Knife radiosurgery (GKRS). Nine patients (25.7%) had previously undergone resection. The median total volume covered in this group of patients was 14.8 cm (range 10.3-24.5 cm). The median tumor margin dose was 11 Gy (range 10-12 Gy). RESULTS The median follow-up duration was 48 months (range 6-156 months). All 35 patients had regular MRI follow-up examinations. Twenty tumors (57.1%) had a volume reduction of greater than 50%, 5 (14.3%) had a volume reduction of 15%-50%, 5 (14.3%) were stable in size (volume change < 15%), and 5 (14.3%) had larger volumes (all of these lesions were eventually resected). Four patients (11.4%) underwent resection within 9 months to 6 years because of progressive symptoms. One patient (2.9%) had open surgery for new-onset intractable trigeminal neuralgia at 48 months after GKRS. Two patients (5.7%) who developed a symptomatic cyst underwent placement of a cystoperitoneal shunt. Eight (66%) of 12 patients with pre-GKRS trigeminal sensory dysfunction had hypoesthesia relief. One hemifacial spasm completely resolved 3 years after treatment. Seven patients with facial weakness experienced no deterioration after GKRS. Two of 3 patients with serviceable hearing before GKRS deteriorated while 1 patient retained the same level of hearing. Two patients improved from severe hearing loss to pure tone audiometry less than 50 dB. The authors found borderline statistical significance for post-GKRS tumor enlargement for later resection (p = 0.05, HR 9.97, CI 0.99-100.00). A tumor volume ≥ 15 cm was a significant factor predictive of GKRS failure (p = 0.005). No difference in outcome was observed based on indication for GKRS (p = 0.0761). CONCLUSIONS Although microsurgical resection remains the primary management choice in patients with VSs, most VSs that are defined as having both a single dimension > 3 cm and a volume > 10 cm and tolerable mass effect can be managed satisfactorily with GKRS. Tumor volume ≥ 15 cm is a significant factor predicting poor tumor control following GKRS.
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http://dx.doi.org/10.3171/2016.12.JNS161530DOI Listing
May 2018

The effect of plant water storage on water fluxes within the coupled soil-plant system.

New Phytol 2017 Feb 21;213(3):1093-1106. Epub 2016 Nov 21.

Nicholas School of the Environment, Duke University, Durham, NC, 27708, USA.

In addition to buffering plants from water stress during severe droughts, plant water storage (PWS) alters many features of the spatio-temporal dynamics of water movement in the soil-plant system. How PWS impacts water dynamics and drought resilience is explored using a multi-layer porous media model. The model numerically resolves soil-plant hydrodynamics by coupling them to leaf-level gas exchange and soil-root interfacial layers. Novel features of the model are the considerations of a coordinated relationship between stomatal aperture variation and whole-system hydraulics and of the effects of PWS and nocturnal transpiration (Fe,night) on hydraulic redistribution (HR) in the soil. The model results suggest that daytime PWS usage and Fe,night generate a residual water potential gradient (Δψp,night) along the plant vascular system overnight. This Δψp,night represents a non-negligible competing sink strength that diminishes the significance of HR. Considering the co-occurrence of PWS usage and HR during a single extended dry-down, a wide range of plant attributes and environmental/soil conditions selected to enhance or suppress plant drought resilience is discussed. When compared with HR, model calculations suggest that increased root water influx into plant conducting-tissues overnight maintains a more favorable water status at the leaf, thereby delaying the onset of drought stress.
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http://dx.doi.org/10.1111/nph.14273DOI Listing
February 2017

The effects of leaf area density variation on the particle collection efficiency in the size range of ultrafine particles (UFP).

Environ Sci Technol 2013 Oct 7;47(20):11607-15. Epub 2013 Oct 7.

Nicholas School of the Environment, Duke University , Durham, North Carolina 27708, United States.

Carbonaceous particles were generated during a "sooting burn" experiment to explore how heterogeneity in horizontal leaf area density (LAD) within the canopy impacts the ultrafine particle (UFP) collection efficiency at the branch-scale. To address this goal, wind tunnel experiments and a particle-size resolving model, which couples the turbulent flow field within the vegetated volume and the collection efficiency, were presented. Three scenarios were examined in a wind-tunnel packed with Juniperus chinensis branches: An LAD that was uniformly distributed, linearly increasing and linearly decreasing along the longitudinal or mean wind direction. The concentration measurements were conducted at multiple locations within the vegetated volume to evaluate the performance of the proposed model needed in discerning the role of LAD heterogeneity on UFP collection. Differences not exceeding 20% were found between modeled and measured concentration for all particle sizes across a wide range of wind speeds. The overall particle collection efficiency was found to be primarily governed by the spatially integrated LAD when differences in aerodynamic attributes (e.g., foliage drag) were accounted for. When combined with earlier studies, the results suggest that one parameter linking the laminar boundary layer conductance to the Schmidt number depends on particle size.
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http://dx.doi.org/10.1021/es4013849DOI Listing
October 2013

Measuring center of pressure signals to quantify human balance using multivariate multiscale entropy by designing a force platform.

Sensors (Basel) 2013 Aug 8;13(8):10151-66. Epub 2013 Aug 8.

Department of Mechanical Engineering, Yuan Ze University, Chung-Li 32003, Taiwan.

To assess the improvement of human body balance, a low cost and portable measuring device of center of pressure (COP), known as center of pressure and complexity monitoring system (CPCMS), has been developed for data logging and analysis. In order to prove that the system can estimate the different magnitude of different sways in comparison with the commercial Advanced Mechanical Technology Incorporation (AMTI) system, four sway tests have been developed (i.e., eyes open, eyes closed, eyes open with water pad, and eyes closed with water pad) to produce different sway displacements. Firstly, static and dynamic tests were conducted to investigate the feasibility of the system. Then, correlation tests of the CPCMS and AMTI systems have been compared with four sway tests. The results are within the acceptable range. Furthermore, multivariate empirical mode decomposition (MEMD) and enhanced multivariate multiscale entropy (MMSE) analysis methods have been used to analyze COP data reported by the CPCMS and compare it with the AMTI system. The improvements of the CPCMS are 35% to 70% (open eyes test) and 60% to 70% (eyes closed test) with and without water pad. The AMTI system has shown an improvement of 40% to 80% (open eyes test) and 65% to 75% (closed eyes test). The results indicate that the CPCMS system can achieve similar results to the commercial product so it can determine the balance.
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http://dx.doi.org/10.3390/s130810151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3812597PMC
August 2013

[The application of piecewise direct standardization with SNV in calibration transfer of Raman spectra].

Guang Pu Xue Yu Guang Pu Fen Xi 2011 May;31(5):1279-82

State Key Lab of Industrial Control Technology, Zhejiang University, Hangzhou 310027, China.

To implement calibration transfer between Raman spectrometers, an improved piecewise direct standardization (PDS) is proposed in the present paper. Standard normal variate (SNV) is firstly introduced to reduce the influence of spectral background and intensity corresponding to the master spectrometer and the slave spectrometer; then PDS algorithm is used to eliminate the differences between Raman spectra for a specific sample. Moreover, a new quantitative criterion, called transfer error rate, is proposed to evaluate the performance of calibration model transfer. This improved PDS is applied to Raman spectral analysis of gasoline. The result shows that the proposed algorithm not only needs a small quantity of transfer samples, but also obtains high transfer accuracy and strong model robustness.
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May 2011

Long-term estimation of soil heat flux by single layer soil temperature.

Int J Biometeorol 2009 Jan 2;53(1):113-23. Epub 2008 Dec 2.

Department of Bioenvironmental Systems Engineering, National Taiwan University, Taipei, 10617, Taiwan.

Soil heat flux is one of the important components of surface energy balance. In this study, long-term estimation of soil heat flux from single layer soil temperature was carried out by the traditional sinusoidal analytical method and the half-order time derivative method of Wang and Bras [Wang and Bras (1999) J Hydrol 216:214-226]. In order to understand the characteristics of soil heat flux and to examine the performances of the two methods, a field experiment was conducted at a temperate and humid grassland in Cork, Ireland. Our results show that the soil heat flux had the same magnitude as the sensible heat flux at this grassland site. It was also demonstrated that the analytical method did not predict the soil heat flux well because the sinusoidal assumption for the temporal variation in soil heat flux was invalid. In contrast, good agreement was found between the soil heat flux measurements and predictions made by the half-order time derivative method. This success suggests that this method could be used to estimate soil heat flux from long-term remotely sensed surface temperature.
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http://dx.doi.org/10.1007/s00484-008-0198-8DOI Listing
January 2009

Magnesium hydroxide extracted from a magnesium-rich mineral for CO2 sequestration in a gas-solid system.

Environ Sci Technol 2008 Apr;42(8):2748-52

Department of Chemical Engineering and Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan.

Magnesium hydroxide extracted from magnesium-bearing minerals is considered a promising agent for binding CO2 as a carbonate mineral in a gas-solid reaction. An efficient extraction route consisting of hydrothermal treatment on serpentine in HCl followed by NaOH titration for Mg(OH)2 precipitation was demonstrated. The extracted Mg(OH)2 powder had a mean crystal domain size as small as 12 nm and an apparent surface area of 54 m2/g. Under one atmosphere of 10 vol% CO2/N2, carbonation of the serpentine-derived Mg(OH)2 to 26% of the stoichiometric limit was achieved at 325 degrees C in 2 h; while carbonation of a commercially available Mg(OH)2, with a mean crystal domain size of 33 nm and an apparent surface area of 3.5 m2/g, reached only 9% of the stoichiometric limit. The amount of CO2 fixation was found to be inversely proportional to the crystal domain size of the Mg(OH)2 specimens. The experimental data strongly suggested that only a monolayer of carbonates was formed on the crystal domain boundary in the gas-solid reaction, with little penetration of the carbonates into the crystal domain.
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http://dx.doi.org/10.1021/es072099gDOI Listing
April 2008