Blood flow index as an indicator of successful sciatic nerve block: a prospective observational study using laser speckle contrast imaging

BACKGROUND

Laser speckle contrast imaging allows real-time, non-invasive, quantitative measurements of regional blood flow. The objectives of this prospective observational study were to use laser speckle contrast imaging to evaluate blood flow changes after sciatic nerve block, and to determine whether this novel optical technique can evaluate block success.

METHODS

This observational study included 63 adult patients undergoing elective lower limb surgery with sciatic nerve block. Blood flow images and blood flow index (BFI) values of toes were recorded using laser speckle contrast imaging 5 min before nerve block and at 5 min intervals until 30 min after sciatic block. The sensitivity, specificity, and cut-off value of laser speckle contrast imaging for predicting successful sciatic block were determined by receiver operator characteristic (ROC) curve analysis.

RESULTS

The BFI values of toes were significantly increased at each time point after successful sciatic block, compared with the baseline value obtained 5 min before nerve block; in failed sciatic block, there were no significant differences. For successful sciatic block, the highest increase of BFI value was at the big toe. BFI increase of the big toe at 10 min after sciatic block has great potential as an indicator of block success. The area under the ROC curve was 0.954 at a cut-off value of 8.48 perfusion units (PU) with a sensitivity of 89% and a specificity of 100%.

CONCLUSIONS

Laser speckle contrast imaging might be an early, objective, quantitative, and reliable indicator of successful sciatic block. BFI increase of the big toe not reaching 8.48 PU within 10 min after sciatic block indicates block failure.

CLINICAL TRIAL REGISTRATION

NCT03169517.

[A multi-center study for the association between the perception and control of disease among asthmatic patients in Chinese urban areas]

Objective: To investigate the current perception of disease among asthmatic patients in Chinese urban areas, and to address its association with asthma control. Methods: This was a nationwide, multi-center, cross-sectional study covering 30 third-level, grade A hospitals in 30 provinces, municipalities and autonomous regions (not including Tibet) across Chinese mainland. The survey was carried out from October 2015 to May 2016. Asthmatic outpatients were selected to receive face-to-face questionnaire survey on asthma control including Asthma Control Test (ACT) score, classification of asthma control level[according to the Global Initiative for Asthma (GINA) 2015 classification system, as assessed by the physician completing the survey], perception of asthma (including question 1: nature of asthma as a disease; question 2: selection of first-line therapeutic agents to be regularly used daily for asthma; question 3: appropriate timing of the use of short-acting aerosols of β(2) receptor agonists; and question 4: therapeutic goals for asthma). Results: A total of 3 875 asthmatic outpatients were included; among them, 69.0% (2 660/3 857) were aware that asthma is "an airway inflammatory disorder resulting from the combined effects of heredity and environment" ; 60.2% (2 321/3 857) considered "inhaled glucocorticoids or their compound preparations" to be the first-line therapeutic agents to be regularly used daily for patients with persistent chronic asthma; 85.7% (3 277/3 823) considered it appropriate to use short-acting aerosols of β(2) receptor agonists "as needed in the event of disease aggravation or acute exacerbation" ; and 75.4% (2 761/3 661) were aware that asthma "can be adequately or completely controlled in the long term" . The ACT score[20 (16, 23) vs 19 (16, 22) points; Z=-3.928, P<0.001]and asthma control rate (29.92% vs 25.31%; χ(2)=8.616, P=0.003) were significantly higher, and the rate of uncontrolled asthma (19.92% vs 23.48%; χ(2)=6.267, P=0.012) was significantly lower among the 2 660 (69.0%) patients correctly answering question 1 than among the 1 197 (31.0%) patients giving incorrect answer. The ACT score[21 (17, 23) vs 19 (15, 22) points; Z=-9.190, P<0.001] and asthma control rate (32.66% vs 22.20%; χ(2)=49.614, P<0.001) were significantly higher, and the rate of uncontrolled asthma (18.40% vs 25.00%; χ(2)=24.267, P<0.001) was significantly lower among the 2 321 (60.2%) patient correctly answering question 2 than among the 1 536 (39.8%) patients giving incorrect answer. Conclusions: Compared to previous surveys, there has been improved perception of disease among asthmatic patients in Chinese urban areas. Correct perception of disease is favorable for improving asthma control level.

[Relationship between hyperuricemia and adverse events in patients aged 40 years or older receiving rheumatic aortic valve replacement]

OBJECTIVE

To explore the prognostic value of hyperuricemia for adverse events in patients >40 years old receiving valve replacement surgery for rheumatic aortic valve disease.

METHDS

Consecutive middle-aged and elderly patients receiving aortic valve replacement surgery for rheumatic aortic valve disease between March, 2009 and July, 2013 were recruited in this study. The patients were divided into hyperuricemic group and normouricemic group based on their serum levels of uric acid, and the clinical data and adverse events within 1 year after the surgery were compared between the 2 groups.

RESULTS

A total of 632 consecutive patients were recruited, including 381 patients with hyperuricemia and 251 with normouricemia. The in-hospital mortality rate was significantly higher in hyperuricemic group than in normouricemic group (7.6% vs 2.0%, P=0.002). Serum uric acid levels were negatively correlated with eGFR (r=-0.421, P<0.001) and positively correlated with C-reactive protein level (r=0.093, P=0.025). Multivariate analysis showed that hyperuricemia was independently associated with the in-hospital mortality (OR=3.07, 95%CI: 1.13-8.37, P=0.028) and mortality at 1 year after the surgery (HR=3.14, 95%CI: 1.30-7.62, P=0.011) after adjusting for potential risk factors including age, NYHA III-IV and postoperative acute kidney injury (AKI). Kaplan-Meier analysis showed that the cumulative rate of 1-year mortality after surgery was significantly higher in patients with hyperuricemia (Log-rank=11.73, P=0.001).

CONCLUSION

Hyperuricemia is a predictor of in-hospital and one-year mortality in middle-aged and elderly patients following aortic valve replacement surgery for rheumatic aortic valve disease.

[Relationship between hyperuricemia and adverse events in patients aged 40 years or older receiving rheumatic aortic valve replacement]

OBJECTIVE

To explore the prognostic value of hyperuricemia for adverse events in patients >40 years old receiving valve replacement surgery for rheumatic aortic valve disease.

METHDS

Consecutive middle-aged and elderly patients receiving aortic valve replacement surgery for rheumatic aortic valve disease between March, 2009 and July, 2013 were recruited in this study. The patients were divided into hyperuricemic group and normouricemic group based on their serum levels of uric acid, and the clinical data and adverse events within 1 year after the surgery were compared between the 2 groups.

RESULTS

A total of 632 consecutive patients were recruited, including 381 patients with hyperuricemia and 251 with normouricemia. The in-hospital mortality rate was significantly higher in hyperuricemic group than in normouricemic group (7.6% vs 2.0%, P=0.002). Serum uric acid levels were negatively correlated with eGFR (r=-0.421, P<0.001) and positively correlated with C-reactive protein level (r=0.093, P=0.025). Multivariate analysis showed that hyperuricemia was independently associated with the in-hospital mortality (OR=3.07, 95%CI: 1.13-8.37, P=0.028) and mortality at 1 year after the surgery (HR=3.14, 95%CI: 1.30-7.62, P=0.011) after adjusting for potential risk factors including age, NYHA III-IV and postoperative acute kidney injury (AKI). Kaplan-Meier analysis showed that the cumulative rate of 1-year mortality after surgery was significantly higher in patients with hyperuricemia (Log-rank=11.73, P=0.001).

CONCLUSION

Hyperuricemia is a predictor of in-hospital and one-year mortality in middle-aged and elderly patients following aortic valve replacement surgery for rheumatic aortic valve disease.

Dramatic band gap reduction incurred by dopant coordination rearrangement in Co-doped nanocrystals of CeO2

A dramatic band gap narrowing of 1.61 eV has been observed in Co-doped nanocrystals of CeO₂ (ceria), as a result of thermal annealing, without changing the ceria crystal structure and the Co concentration. As demonstrated by x-ray absorption fine structures, thermal annealing incurs an oxygen coordination rearrangement around Co atoms from an octahedral coordination to a square-planar coordination. First principle calculation using density functional theory reveals two stable oxygen coordination types surrounding Co, consistent with the experimental observation. The band gap values calculated for the two stable coordination types differ dramatically, reproducing the experimentally observed band gap narrowing. These prominent effects due to local structure rearrangement around dopant atoms can lead to unprecedented methods for band gap engineering in doped nanocrystal oxides.

Tiapride is more effective and causes fewer adverse effects than risperidone in the treatment of senile dementia

OBJECTIVE

We wanted to compare the effects of tiapride and risperidone in treating behavioral and psychological symptoms of senile dementia.

PATIENTS AND METHODS

108 patients with senile dementia received respective treatments (54 patients per treatment, either with 100 mg/day risperidone or 2.0 mg tiapride/day) for 2 months. Outcomes included the positive and negative syndrome scale (PANSS) scores, the curative rate of senile dementia, and prevalence of adverse effects (somnolence, headache, loss of weight, extrapyramidal system response, irritation and insomnia).

RESULTS

PANSS scores before treatment were comparable between treatment groups. On days 7, 15, 30, and 60 of the treatment, the differences between two treatment groups became evident. Thus, curative rates in patients treated with risperidone were 74.1% and in those treated with tiapride 88.9% (p < 0.05). Prevalence of adverse reactions was significantly lower in the latter group (9.3% vs. 25.9% in patients treated with risperidone; p < 0.05).

CONCLUSIONS

Tiapride is more effective in improving clinical symptoms of senile dementia and causes fewer adverse effects.

Diagnostic performance of anti-citrullinated protein/peptide antibodies in juvenile idiopathic arthritis

The prevalence rates of anti-citrullinated protein/peptide antibodies (ACPAs) were investigated in a cohort of juvenile idiopathic arthritis (JIA) patients, and their diagnostic performances were compared. ACPAs, including anti-cyclic citrullinated peptide IgG (anti-CCP), anti-CCP IgG/IgA (anti-CCP3.1), citrullinated recombinant rat filaggrin antibodies (CPA), anti-mutated citrullinated vimentin (anti-MCV), and antibodies to citrullinated human IgG-derived peptides (RA/CP), were measured in the sera from 81 JIA patients. Serum samples from 55 children with other joint diseases or viral infections and 49 healthy donors were tested as controls. Of the 81 JIA patients, 7 (8.6%), 8 (9.9%), 17 (21.0%), 23 (28.4%), and 18 (22.2%) were found to be positive for anti-CCP, anti-CCP3.1, CPA, anti-MCV, and RA/CP, respectively, with specificities of 98.1, 95.1, 93.3, 84.6, and 86.5%. Analysis by subtype revealed that 7/7 (100%) of RF-positive polyarticular JIA patients tested positive at high serum levels for anti-MCV or RA/CP, and 5/7 (71.4%) were positive for anti-CCP, anti- CCP3.1, or CPA (P < 0.001, compared with controls). Eighteen of 81 JIA patients demonstrated joint erosions on radiographs and erosive arthritis occurred more often in ACPAs positive patients (P < 0.01). Our findings indicate that although ACPAs are not satisfactory screening biomarkers for JIA due to low sensitivity, ACPA measurement can aid in diagnosing RF-positive polyarticular JIA and identifying JIA patients with severe bone involvement. The diagnostic performance of each ACPA in JIA is different, and the careful selection of assays is necessary.

Investigating the recheck rules for urine analysis in children

The aim of this study was to establish recheck rules of urinalysis in children by investigating the concordance rate of the results obtained using the LabUMat urine dry chemistry analyzer (referred to as dry chemistry) and the UriSed tangible composition analyzer with that of the microscopic examination. First, 1040 urine samples from children (mean age 6.5 years) were analyzed using LabUMat and UriSed analyzers, and subsequently subjected to microscopic examination. The missed detection rate was evaluated and recheck rules were established to avoid missed diagnoses of abnormal renal function. Finally, clinical validations of the recheck rules were performed on 200 additional specimens. Among the samples used to investigate the recheck rules, the samples with positive microscopic examination results accounted for 58.65% of the total, while the samples with negative results accounted for 41.35%. Of the positive samples, a major portion (>50%) were RBC positive. The samples that were WBC positive and CAST positive accounted for 23.08 and 7.69%, respectively. The concordance rate was 87.5% and the missed detection rate was 2.9%. For the validation of the recheck rules in 200 urine samples, the concordance rate was 87.5% and the missed detection rate was 2.4%. When the detection of occult blood, WBC, and protein by dry chemistry, and the detection of RBC, WBC, and CAST by the UriSed analyzer are inconsistent, or the differences between them greater than 2 levels, recheck by microscopic examination is suggested.

Theoretical and experimental studies for high-repetition-rate disordered crystal lasers with harmonic self-mode locking

A harmonically self-mode-locked Nd:Sr3Y2/(BO3)4 disordered crystal laser with subpicosecond pulse duration is demonstrated. We exploit the damped harmonic oscillator model to numerically verify that the mode spacing of the laser cavity can be modified to be the harmonics of the free spectral range of the Fabry-Perot cavity when the optical length of the laser cavity is close to a commensurate ratio of the optical length of the Fabry-Perot cavity. In experiment, the Fabry-Perot cavity can be formed by the pump facet of the disordered crystal and the front mirror. A 110 GHz single-pulse harmonically mode-locked pulse train with pulse duration of 857 fs is experimentally achieved under optical lengths of 27.19 and 4.08 mm for the laser cavity and Fabry-Perot cavity respectively, corresponding to a fractional number of 20/3. A maximum output power of 162 mW is obtained at an incident pump power of 3.1 W.

Identification of environmentally stable QTL for resistance against Leptosphaeria maculans in oilseed rape (Brassica napus)

Six stable QTL for resistance against L. maculans (phoma stem canker) have been identified by QTL × environment interaction analysis using data from five winter oilseed rape field experiments. Phoma stem canker, caused by Leptosphaeria maculans, is a disease of worldwide importance on oilseed rape (Brassica napus). Quantitative trait loci (QTL)-mediated resistance against L. maculans in B. napus is considered to be race non-specific and potentially durable. Identification and evaluation of QTL for resistance to L. maculans is important for breeding oilseed rape cultivars with durable resistance. An oilseed rape mapping population was used to detect QTL for resistance against L. maculans in five winter oilseed rape field experiments under different environments. A total of 17 QTL involved in 'field' quantitative resistance against L. maculans were detected and collectively explained 51% of the phenotypic variation. The number of QTL detected in each experiment ranged from two to nine and individual QTL explained 2-25% of the phenotypic variation. QTL × environment interaction analysis suggested that six of these QTL were less sensitive to environmental factors, so they were considered to be stable QTL. Markers linked to these stable QTL will be valuable for selection to breed for effective resistance against L. maculans in different environments, which will contribute to sustainable management of the disease.

Pre-PCI medication using clopidogrel and ticagrelor in the treatment of patients with acute myocardial infarction

OBJECTIVE

This study aimed to compare preoperative treatment using clopidogrel and ticagrelor for patients with acute myocardial infarction (AMI) undergoing emergent percutaneous coronary intervention (PCI), and to investigate the efficacy and safety of these medications in the management of AMI.

PATIENTS AND METHODS

Between February 2013 and December 2014, 74 patients with AMI admitted for emergent PCI therapy were included in the study and randomly divided into two groups: study group and control group. Patients in the study group received different pre-PCI treatment with a loading dose of 180 mg ticagrelor, and those in the control group received treatments with a loading dose of 600 mg clopidogrel. After PCI procedure, all patients were orally administered 75 mg clopidogrel once a day for maintenance therapy, and patients were monitored for one week at the hospital and further followed up for one month Platelet aggregation rates (PAR) of each patient was measured before medication, at 30 min, 2h, 24h and one week after medication, respectively. PAR, thrombolysis in myocardial infarction (TIMI) flow, clinical outcomes and adverse reactions were compared between groups.

RESULTS

No significant differences were observed in PAR before treatment between groups (p>0.05), whereas PARs were significantly different after treatment between groups (p<0.05), with the efficacy of medications peaking at 2h after the treatment. In addition, PARs were significantly different between different time points after treatment (p<0.05). Evaluation of TIMI flow grade showed that in study group, 6 patients (16.22%) were grade 2 and 31 (83.78%) were grade 3 for the study group; for the control group, 11 patients (27.73%) were grade 2 and 26 (72.27%) were grade 3. No significant differences were observed in TIMI flow grades between different groups (p>0.05). No recurrence of the disease was observed, but one case (2.70%) of mucosal bleeding in the nasal cavity and four cases (10.81%) of vomiting were found in the study group. However, in the control group, four patients (10.81%) presented with recurrent disease, six patients (16.22%) experienced mucosal bleeding in the nasal cavity and 11 patients (29.73%) vomited. Significant differences were observed in the incidence of adverse events between different groups (p<0.05).

CONCLUSIONS

Compared with 600 mg clopidogrel, a loading dose of 180 mg ticagrelor could effectively inhibit platelet reactivity at the early stage of AMI, resulting in more favorable clinical outcomes and lower occurrence of adverse events and, thereby, can be used in clinical practice.

Potential involvement of placental AhR in unexplained recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is a common complication of pregnancy. Recent studies have demonstrated that the aryl hydrocarbon receptor (AhR) might play important roles in establishing and maintaining early pregnancy. In this study, we found that placental AhR protein levels were significantly lower and placental CYP1A1 mRNA levels were higher in unexplained RSA (URSA) patients than in control subjects. The results of immunohistochemical analyzes showed that placental AhR was expressed in syncytiotrophoblast cells and that the level of AhR was markedly lower in these cells in URSA subjects than in control subjects. β-Naphthoflavone (β-NF, an AhR ligand) at 5μM significantly inhibited proliferation and migration in HTR-8/SVneo cells and was associated with the activation of AhR. Moreover, overexpressing AhR in JAR cells significantly increased CYP1A1 mRNA levels and inhibited cell migration. These results indicate that AhR is highly activated in URSA placentas and that the activation of AhR in the placenta might impair trophoblast cell proliferation and migration, possibly leading to the occurrence of URSA.

Dual-wavelength eye-safe Nd:YAP Raman laser

We report on a diode-pumped, Q-switched intracavity-Raman-shifted Nd-doped yttrium-aluminum-perovskite (Nd:YAP) laser using potassium titanyl phosphate (KTP) or potassium titanyl arsenate (KTA) nonlinear crystals to produce eye-safe radiation. In both cases, we obtained simultaneous laser emission at two wavelengths corresponding to distinct Raman gain peaks and different Stokes orders for the nonlinear crystal used. From the Nd:YAP/KTP laser source, we obtained 3 ns pulses of combined 21 kW peak power at 1478 and 1503 nm. From the Nd:YAP/KTA laser source, we obtained up to 220 mW total average output power, equally split between 1474 and 1480 nm emission lines.

Study on the correlation between the expression of Ki67 and FasL and prognosis of cervical carcinoma

This study aimed to investigate the correlation between the expression of Ki67 and FasL and prognosis of cervical carcinoma and to explore the biological processes and signal pathways related to cervical carcinoma. Cervical carcinoma tissue specimens from 200 patients and normal tissue specimens adjacent to lesions from 30 cases were collected in this study. Ki67 and FasL proteins in these specimens were detected by immunohistochemical methods. A series of statistical methods were carried out to investigate the correlation between the expression of Ki67 and FasL and prognosis of cervical carcinoma. The expression of Ki67 and FasL in cervical carcinoma tissues was significantly higher than that in normal cervical tissue. The positive rate of Ki67 and FasL increased with the increase in the degree of cervical lesions. There was a positive correlation between the expression of Ki67 and FasL in cervical lesions. The expression of Ki67 and FasL affected the five-year survival rate of postoperative patients. Ki67 and FasL were independent factors for the prognosis of patients with cervical cancer. The expression of Ki67 and FasL is closely related to the occurrence and development of cervical carcinoma. There is a positive correlation between Ki67 and FasL, and they may be biomarkers of cervical cancer.

Comparative study of intracavity KTP-based Raman generation between Nd:YAP and Nd:YAG lasers operating on the (4)F(3/2) → (4)I(13/2) transition

Extending the spectral wavelengths of the diode-pumped Nd-doped lasers at 1.3 μm with the KTP crystal in the intracavity Raman configuration is reported for the first time to the best of our knowledge. A systematic comparison is performed to show that a better optical conversion efficiency for the Nd:YAP/KTP Raman laser could be achieved thanks to the higher peak power and linearly polarized radiation at 1341 nm, whereas up to four Stokes emission lines are generated from the Nd:YAG/KTP Raman laser as a result of the fundamental dual-color operation at 1319 and 1338 nm. The maximum Stokes output power of the developed Nd:YAP/KTP Raman laser reaches 1.04 W under an incident pump power of 16 W and a pulse repetition rate of 10 kHz, corresponding to the diode-to-Stokes conversion efficiency as high as 6.5%. The largest pulse energy and highest peak power are evaluated to be up to 104 μJ and 34.7 kW, respectively.

Nd:YLF laser at cryogenic temperature with orthogonally polarized simultaneous emission at 1047 nm and 1053 nm

A Nd:YLF laser at cryogenic temperature is demonstrated for the first time with orthogonally polarized simultaneous emission at 1047 nm and 1053 nm. By exploring the temperature dependence of the fluorescence and the absorption spectra from the Nd:YLF crystal, the feasibility of simultaneous emission at low temperature is achieved. Due to the local heating from the pump absorption, the optimal temperature with respect to the pump power for balancing output powers of simultaneous emission is thoroughly explored. At the optimal temperature of 138 K, the total output power of the simultaneous emission can reach 3.1 W at an incident pump power of 7.9 W, corresponding to the optical to optical slope efficiency up to 43%.

Biomechanical study of the funnel technique applied in thoracic pedicle screw replacement

BACKGROUND

Funnel technique is a method used for the insertion of screw into thoracic pedicle.

AIM

To evaluate the biomechanical characteristics of thoracic pedicle screw placement using the Funnel technique, trying to provide biomechanical basis for clinical application of this technology.

METHODS

14 functional spinal units (T6 to T10) were selected from thoracic spine specimens of 14 fresh adult cadavers, and randomly divided into two groups, including Funnel technique group (n = 7) and Magerl technique group (n = 7). The displacement-stiffness and pull-out strength in all kinds of position were tested and compared.

RESULTS

Two fixed groups were significantly higher than that of the intact state (P < 0.05) in the spinal central axial direction, compression, anterior flexion, posterior bending, lateral bending, axial torsion, but there were no significant differences between two fixed groups (P > 0.05). The mean pull-out strength in Funnel technique group (789.09 ± 27.33) was lower than that in Magerl technique group (P < 0.05).

CONCLUSIONS

The Funnel technique for the insertion point of posterior bone is a safe and accurate technique for pedicle screw placement. It exhibited no effects on the stiffness of spinal column, but decreased the pull-out strength of pedicle screw. Therefore, the funnel technique in the thoracic spine affords an alternative for the standard screw placement.

Design, synthesis and alpha1-adrenoreceptor blocking activity of new arylpiperazines containing acetophenone substituents

Alpha1-AR antagonists are currently first-line therapy for lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH). In this study, we report the synthesis of a new series of arylpiperazine derivatives containing acetophenone (3-17) which possess alpha1-adrenoreceptor blocking activity. The in vitro alpha1-adrenoreceptor blocking activity of each derivative was first screened using rabbit thoracic aortic rings by measuring the relaxation response (%) activated by (-)-noradrenaline (3 microM). Compounds 6 and 7 with 2,5-dimethoxy and 2-ethoxy substituent were found to have significant vasodilatory effect. Since the presence of a chiral carbon in the structure, 6 and 7 together with their enantiomers 14-17 were further evaluated by testing diastolic effect on rabbit thoracic aorta, prostate and bladder smooth muscle. The S-enantiomer was found to have more potent diastolic activity than the R-enantiomer and racemate, 17 being the most effective alpha1-adrenoreceptor antagonist. In order to assess tissue selectivity, the antagonistic effect of 17 on the (-)-noradrenaline induced contractile response of isolated rat vas deferens (alpha(1A)), spleen (alpha(1B)) and aorta (alpha(1D)) was characterized finally. Compared with naftopidil (1) and terazosin, compound 17 exhibited higher selectivity (18-fold) for the alpha(1D)-adrenoceptor subtype as compared to the alpha(1B)-adrenoceptor subtype, indicating less cardiovascular side effects for the treatment of LUTS/BPH. These data suggest that the acetophenone is a new effective adrenergic receptor ligand as well as incentivizes further research regarding pharmacological properties of chiral molecules.

High-repetition-rate quasi-CW side-pumped mJ eye-safe laser with a monolithic KTP crystal for intracavity optical parametric oscillator

We demonstrate a high-repetition-rate millijoule passively Q-switched eye-safe Nd:YVO(4) laser pumped by a quasi-CW diode stack. A theoretical analysis has been explored for the design criteria of generating TEM(n,0) mode in the diode-stack directly side-pumping configuration. We successfully generate TEM(n,0) modes at 1064 nm by adjusting the gain medium with respected to the laser axis. We further observe the spatial cleaning ability for generating an nearly TEM(0,0) mode output at 1573 nm with a monolithic OPO cavity. At the repetition rate up to 200 Hz, the output pulse energy reaches 1.21 mJ with the threshold pump energy of 17.9 mJ.

Efficient high-power terahertz beating in a dual-wavelength synchronously mode-locked laser with dual gain media

We originally present a novel tactic to accomplish a compact efficient dual-wavelength synchronously mode-locked laser by physically combining the Nd:YVO4 crystal to the Nd:GdVO4 crystal as a composite gain medium. With the developed method, the total output power at 1.06 μm could be effectually produced to reach 1.3 W under the optimally balanced two-color intensities. The corresponding mode-locked pulse width and repetition rate are measured to be 47 ps and 2.86 GHz, respectively. Through the optical beating between two carrier frequencies of dual-color synchronous pulses, a train of 0.32 THz ultrashort pulses is further generated with the effective duration of down to 1.6 ps.

Diluted hydrochloric acid generates larger radiofrequency ablation lesions in excised porcine livers

PURPOSE

This study evaluated the influence of continuous infusion of diluted hydrochloric acid during radiofrequency ablation (RFA) on the size of ablated lesions.

MATERIALS AND METHODS

Experiments were performed in 20 excised porcine livers using three different treatment modalities: (1) normal saline-enhanced RFA (NS-RFA), which was normal saline pumped into ablated tissue during RFA; (2) diluted hydrochloric acid ablation (DHAA), which was 3 mol/L diluted hydrochloric acid (HCl) injected into hepatic tissue without RFA; and (3) HCl-enhanced RFA (HCl-RFA), which was 3 mol/L diluted HCl continuously infused into ablated tissue during RFA. We produced 20 HCl-RFA and NS-RFA lesions, respectively, using a monopolar perfusion electrode connected to a commercially available radiofrequency generator, and 20 DHAA lesions using an 18-gauge Chiba needle. The ablated lesions were evaluated both macroscopically and histologically. Dimensions of lesions were compared among HCl-RFA, NS-RFA, and DHAA.

RESULTS

The ablated lesions had an elliptical-like shape and were well-demarcated with normal liver tissue. The mean volume, longitudinal diameter, and transverse diameter of NS-RFA lesions were 11.24±0.29 cm(3), 3.4±0.07 cm, and 2.48±0.03 cm, those of HCl-RFA lesions were 58.14±3.05 cm(3), 5.51±0.05 cm, and 4.49±0.11 cm, and those of DHAA lesions were 4.41±0.16 cm(3), 2.43±0.08 cm, and 1.8±0.03 cm, respectively. The mean dimensions of HCl-RFA lesions were the largest among the three types of ablation (P < 0.001).

CONCLUSION

Under the present experimental conditions, the continuous infusion of diluted HCl during RFA can generate larger ablated lesions than NS-RFA or DHAA in excised porcine livers.

High-power tunable single- and multi-wavelength diode-pumped Nd:YAP laser in the (4)F3/2 → (4)I11/2 transition

We experimentally explore the fluorescent spectrum of the Nd:YAP crystal to manifest the feasibility of tunable single- and multi-wavelength operations in the (4)F3/2 → (4)I11/2 transition. An intracavity etalon is subsequently exploited to effectively select spectral lines at 1073, 1080, and 1084 nm with the tunabilities of 0.56, 1.13, and 0.1 nm, respectively. We also experimentally obtain multi-wavelength oscillations among various intermanifold lines in the Nd:YAP crystal with the output powers on the order of several watts for each group. Employing the Cr(4+):YAG crystal to realize the passively Q-switched operation, the maximum average output powers as high as 2.3 and 3.5 W for 1073 and 1080 nm are obtained. The corresponding pulse energies at 1073 and 1080 nm are up to 177 and 159 μJ, respectively.

High-power diode-end-pumped laser with multi-segmented Nd-doped yttrium vanadate

A Nd:YVO4 crystal consisting of three segments with different doping concentrations is originally developed for power scaling in diode-end-pumped solid-state laser. We systematically make a comparison of laser characteristics between the multi-segmented and conventional composite crystals to show the feasibility of using gain medium with multiple doping concentrations for power scale-up in end-pumped laser without introducing significant thermally accompanied effects. We further construct a dual-end-pumped actively Q-switched oscillator at 1064 nm to verify the usefulness of our crystal design, where the largest pulse energy of 1.06 mJ and the highest output power of 45 W are efficiently generated.