Damage Characteristics Analysis of Laser Ablation Triple-Junction Solar Cells Based on Electroluminescence Characteristics.

To study the physical property effects of the laser on GaInP/GaAs/Ge solar cells and their sub-cell layers, a pulsed laser with a wavelength of 532 nm was used to irradiate the solar cells under various energy conditions. The working performance of the cell was measured with a source meter. The electroluminescence (EL) characteristics were assessed using an ordinary and an infrared camera. Based on the detailed balance theory, in the voltage characteristics of an ideal pristine cell, the GaInP layer made the most significant voltage contribution, followed by the GaAs layer, with the Ge layer contributing the least. When a bias voltage was applied to the pristine cell, the top GaInP cell emitted red light at 670 nm, the middle GaAs cell emitted near-infrared light at 926 nm, and the bottom Ge cell emitted infrared light at 1852 nm. In the experiment, the 532 nm laser wavelength within the response spectrum bands of the GaInP layer and the laser passed through the glass cover slip and directly interacted with the GaInP layer. The experimental results indicated that the GaInP layer first exhibited different degrees of damage under laser irradiation, and the cell voltage was substantially attenuated. The GaInP/GaAs/Ge solar cell showed a decrease in electrical and light emission characteristics. As the laser energy increased, the cell's damage intensified, gradually leading to a loss of photoelectric conversion capability, the near-complete disappearance of red light emission, and a gradual degradation of near-infrared emission properties. The EL imaging revealed varying damage states across the triple-junction gallium arsenide solar cell's sub-cells.

Temporal and Spatial Distribution Characteristics of Crosstalk Lines Generated by Irradiating Progressive Scan Charge-Coupled Device Camera with Continuous Laser.

To study the interference effect of the laser in motion mode on a CCD, the continuous laser with the wavelength of 532 nm at different motion speeds was used to scan the CCD. The experimental results show that the crosstalk phenomenon produced by static and dynamic irradiation is significantly different. When the continuous laser statically radiates the CCD, the vertical crosstalk line is observed in the output image. The gray values of the crosstalk line are divided into two stages, with the increase of the laser fluence: linear increase and saturation, which correspond to different formation mechanisms of the crosstalk lines, respectively. In addition, when the irradiation duration of the static laser is less than the integration time of CCD, the effect of delay time on the spatial distribution of the crosstalk line is identified. In addition, when the laser irradiates the CCD at different scanning speeds, crosstalk lines with certain slopes are observed. The slope of the crosstalk line is determined by the scanning speed of the continuous laser and the integration time of the CCD. The results show that the delay time and the irradiation position have important effects on the spatial distribution of the laser spot and crosstalk lines.

Finite element analysis and a pilot study of different fixation constructs for Danis-Weber A and B lateral malleolus fractures.

BACKGROUND: Displaced lateral malleolus fractures are typically stabilised through open reduction and internal fixation. The biomechanically and clinically efficacy of locking plates and lag screws, particularly in Weber A and B distal fibular fractures remains a subject of contention. This study examines two locking plate designs for lateral malleolus fractures, evaluating their performance with and without interfragmentary screws using finite element models. METHODS: Utilising CT images of a healthy adult male volunteer, a three-dimensional finite element model was constructed. The Fibula-specific Flank Multiaxial Locking Anatomic Plate (FMLP) and the Conventional Locking Plate (CLP) were subjected to stabilisation, both with and without an interfragmentary screw, mimicking the Danis-Weber A and B lateral malleolus oblique fracture fixation. Loads of 140 N and 70 N, equivalent to 20% of the body weight, were applied to simulate the single-leg and two-leg standing conditions in the axial direction. The von Mises stress (VMS) distributions and element displacements were subsequently analyzed. RESULTS: In the Danis-Weber A fracture model group, the FMLP with an interfragmentary screw fixation exhibited the lowest peak VMS values: 51.9 MPa in the fibula, 89.0 MPa in the plate, and 61.3 MPa in the screws for simulating single-leg conditions. Under two-leg standing conditions, these peak VMS values decreased to 25.9 MPa in the fibula, 44.5 MPa in the plate, and 30.6 MPa in the screws, respectively. Furthermore, the overall structural peak displacements during single-leg standing for both Weber-A and B fractures with different implants ranged from 1.61 to 2.54 mm. While standing on two feet, the ranged was from 0.80 to 1.27 mm. An interfragmentary screw at the oblique fracture site resulted in reduced the peak value of VMS in the fibula, plate, screws, consequently decreased the overall structural displacement for FMLP and CLP fixation in lateral malleolus fractures. CONCLUSIONS: The current finite element analysis (FEA) demonstrates that FMLP exhibits superior mechanical characteristics in Danis-Weber A and B lateral malleolus fractures compared to CLP. The inclusion of an interfragmentary screw, combined with locking plate design, enhances stability for simple oblique distal fibular fractures. The FMLP presents itself as potential as an alternative for lateral malleolus fractures from a biomechanical perspective. Nevertheless, further verification of these results is imperative through subsequent clinical studies.

Transmissive Mode Laser Micro-Ablation Performance of Ammonium Dinitramide-Based Liquid Propellant for Laser Micro-Thruster.

The transmissive mode laser micro-ablation performance of near-infrared (NIR) dye-optimized ammonium dinitramide (ADN)-based liquid propellant was investigated in laser plasma propulsion using a pulse YAG laser with 5 ns pulse width and 1064 nm wavelength. Miniature fiber optic near-infrared spectrometer, differential scanning calorimeter (DSC) and high-speed camera were used to study laser energy deposition, thermal analysis of ADN-based liquid propellants and the flow field evolution process, respectively. Experimental results indicate that two important factors, laser energy deposition efficiency and heat release from energetic liquid propellants, obviously affect the ablation performance. The results showed that the best ablation effect of 0.4 mL ADN solution dissolved in 0.6 mL dye solution (40%-AAD) liquid propellant was obtained with the ADN liquid propellant content increasing in the combustion chamber. Furthermore, adding 2% ammonium perchlorate (AP) solid powder gave rise to variations in the ablation volume and energetic properties of propellants, which enhanced the propellant enthalpy variable and burn rate. Based on the AP optimized laser ablation, the optimal single-pulse impulse (I)~9.8 µN·s, specific impulse (Isp)~234.9 s, impulse coupling coefficient (Cm)~62.43 dyne/W and energy factor (η)~71.2% were obtained in 200 µm scale combustion chamber. This work would enable further improvements in the small volume and high integration of liquid propellant laser micro-thruster.

Liquid-solid phase regulating excited-state intramolecular proton transfer process of HBT-d-NO2: A QM/MM study.

The excited-state intramolecular proton transfer process of 2-(1,3-benzothiazol-2-yl)-4-[2-(4-nitrophenyl)ethynyl]phenol (HBT-d-NO2) in the different surrounding environment is investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The optimized molecular structure provides convincing evidence that the intramolecular hydrogen bond is strengthened in the first excited (S1) state. The frontier molecular orbitals observed the HBT-d-NO2 exists obvious intramolecular charge translate phenomenon. The results of the potential energy curve show that HBT-d-NO2 is difficult to undergo proton transfer in the ground (S0) state due to the high energy barrier, while it becomes easier in the S1 state in both liquid and solid phases. By comparison, the energy barrier of ESIPT in the solid phase is higher than that in the liquid phase. We can conclude that the solid phase effectively hinders the ESIPT process compared with that the liquid phase. In this work, we illustrate the influence of liquid and solid phases on the intramolecular proton transfer process, which could promote further developments in biomedical and fluorophore applications.

Novel Au Nanoparticle-Modified ZnO Nanorod Arrays for Enhanced Photoluminescence-Based Optical Sensing of Oxygen.

Novel optical gas-sensing materials for Au nanoparticle (NP)-modified ZnO nanorod (NR) arrays were fabricated using hydrothermal synthesis and magnetron sputtering on Si substrates. The optical performance of ZnO NR can be strongly modulated by the annealing temperature and Au sputtering time. With exposure to trace quantities of oxygen, the ultraviolet (UV) emission of the photoluminescence (PL) spectra of Au/ZnO samples at ~390 nm showed a large variation in intensity. Based on this mechanism, ZnO NR based oxygen gas sensing via PL spectra variation demonstrated a wide linear detection range of 10-100%, a high response value, and a 1% oxygen content sensitivity detection limit at 225 °C. This outstanding optical oxygen-sensing performance can be attributed to the large surface area to volume ratio, high crystal quality, and high UV emission efficiency of the Au NP-modified ZnO NR arrays. Density functional theory (DFT) simulation results confirmed that after the Au NPs modified the surface of the ZnO NR, the charge at the interface changed, and the structure of Au/ZnO had the lowest adsorption energy for oxygen molecules. These results suggest that Au NP-modified ZnO NR are promising for high-performance optical gas-sensing applications.

[Comparison of clinical efficacy of subchondral blocking technique combined with plate-screw biplanar fixation and simple plate-screw support peripheral block fixation in the treatment of complex posterior wall acetabular fracture].

OBJECTIVE: To investigate the clinical effect of subchondral blocking technique combined with plate and screw biplane fixation in the treatment of complex acetabular posterior wall fractures. METHODS: From July 2015 to December 2019, a total of 47 cases of acetabular posterior wall fractures were treated. According to the different internal fixation techniques, they were divided into the external blocking fixation group supported by lateral plate and screw(control group of 23 cases) and the subchondral blocking technique combined with lateral plate and screw support biplane fixation group(study group of 24 cases). In the control group, there were 15 males and 8 females, aged 18 to 68 years old with an average of (40.9±7.2) years;preoperative preparation was 4 to 13 days with an average of (7.9±1.5) days. In the study group, there were 14 males and 10 females, aged 20 to 71 years old with an average of (41.7±7.9) years;preoperative preparation was 4 to 12 days with an average of (7.5±1.9) days. Kocher-Langenbeck approach was used in both groups and all patients were followed up for at least 1 year. The operation time, intraoperative blood loss, hospitalization time, quality of fracture reduction after operation, modified Merle D'Aubigne Postel score of hip joint one year after operation and postoperative complication rate of two groups were statistically analyzed and compared. RESULTS: The patients in both groups were followed up for at least 1 year. One year after operation, the Merled'Aubigne Postel score(16.042±1.517) of hip function improvement in the study group was significantly higher than that in the control group (14.696±1.222)(P<0.05). There was no significant difference in operation time and intraoperative bleeding between the two groups(P>0.05). One year after operation, there was a significant difference between two groups in the evaluation results of Matta fracture reduction quality(P<0.05). There was no significant difference in postoperative complications between two groups(P>0.05). CONCLUSION: The treatment of complex acetabular posterior wall fracture with subchondral blocking technique combined with plate and screw biplane fixation technique has lower postoperative complication rate, better functional recovery of hip joint and satisfactory clinical effect.

Interface Adhesion Property and Laser Ablation Performance of GAP-PET Double-Layer Tape with Plasma Treatment.

In the field of laser ablation micro-propulsion, the property of double-layer tape has significant impact on the propulsion performance. In this paper, low temperature plasma was used to treat the surface of polyethylene terephthalate (PET) to improve its adhesion with energetic polymer. The PET surface pre- and post-plasma treatment was characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), and the enhancement mechanism of the interface adhesion was discussed. In addition, the ablation performance of the double-layer tape after the plasma treatment was studied. The results showed that the plasma etching effect increased the root mean square roughness of the PET surface from 1.74 nm to 19.10 nm. In addition, after the plasma treatment, the number of C-OH/COOH bonds and O=C-O bonds increased, which also greatly improved the adhesion between the PET and energetic polymers. In the optimization of the ablation performance, the optimal laser pulse width was about 200 µs. The optimal values of the specific impulse (Isp), impulse coupling coefficient (Cm), and ablation efficiency (η) were 390.65 s, 250.82 µN/W, and 48.01%, respectively. The optimization of the adhesion of the double-layer tape and the ablation performance lay the foundation for the engineering application of laser ablation micro-thrusters.

[Effect analysis of trajectory screw technique in fragility fracture of pelvic ring].

OBJECTIVE: To assess the clinical efficacy of minimally invasive technology with trajectory screw fixation for fragility fractures of pelvic(FFP). METHODS: A retrospective case control study was performed to analyze the clinical data of 35 patients with FFP who were treated and followed up between January 2016 and December 2019. There were 12 males and 23 females, aged from 65 to 99 years with an average of(75.4±7.8) years old. There were 13 cases of type Ⅱb, 7 cases of type Ⅱc, 8 cases of type Ⅲa, 2 cases of type Ⅲb, 2 cases of type Ⅲc, 1 case of type Ⅳb, and 2 cases of type Ⅳc according to Rommens FFP comprehensive classification. All patients received the treatment of minimally invasive technology with trajectory screws fixation. According to the different methods of anterior pelvic ring fixation, FFP patients were divided into two groups:12 cases were fixed with the pedicle screw rod system in the anterior pelvic subcutaneous internal fixator (INFIX) group;23 cases were fixed with hollow screws of the pubic symphysis, superior ramus of pubis or acetabular anterior column in the screw group. The operation time, intraoperative blood loss, intraoperative fluoroscopy times, length of hospital stay, cost of internal fixation, pre- and post-operative visual analogue scale(VAS) were compared between the two groups. The fracture reduction quality was evaluated according to the Matta criteria, and the clinical function was evaluated by the Majeed functional scoring system respectively. RESULTS: All patients were followed up for 12 to 39(16.5±5.4) months after surgery. There was no statistically significant difference in the operation time, intraoperative blood loss, intraoperative fluoroscopy time, and length of hospital stay between the two groups(P>0.05). As for the cost of internal fixation, the cost of internal fixation in the screw group [2 914 (2 914, 4 371) yuan] was significantly lower than that of the INFIX group [6 205 (6 205, 6 205) yuan] (P<0.05). No significant difference was observed in the incidence of postoperative complications between the two groups (P>0.05). There was no significant difference in VAS assessment at admission, 1 week, and 3 months after surgery between the two groups(P>0.05). However, the VAS assessment at 1 week and 3 months after surgery of the two groups were significantly better than those at admission(P<0.05). There was no significant difference in the quality of fracture reduction after the operation and the efficacy evaluation at the last follow-up between the two groups(P>0.05). CONCLUSION: For the treatment of fragility fractures, minimally invasive technology with trajectory screw fixation can achieve good clinical efficacy. It has the advantages of being relatively minimally invasive, less bleeding, relieving the pain. It deserves clinical application.

Photoluminescence-based sensing of ethanol gas with ultrafine WO3 nanorods.

Ultrafine one-dimensional WO3 nanorods (NRs) with diameters of 10-200 nm have been fabricated using a hydrothermal synthesis method. The optical performance of the WO3 NRs strongly depends on their various defects as well as their crystal quality. Upon exposure to trace quantities of ethanol gas, the photoluminescence (PL) spectra of these nanorod samples under ultraviolet illumination showed a large variation in intensity. WO3-NR-based ethanol gas sensing via PL spectra variation demonstrated a 100 ppm sensitivity detection limit and a wide linear detection range of 200-2000 ppm at 100°C. This outstanding optical ethanol sensing performance can be ascribed to the very large surface area to volume ratio of this material, which increases the density of active sites for ethanol adsorption and reaction with adsorbed oxygen species.

[Analysis of clinical effects of iliolumbar fixation in treating U-shaped sacral fractures].

OBJECTIVE: To evaluate the efficacy of iliolumbar fixation in the treatment of U-shaped sacral fractures. METHODS: A retrospective study was conducted on the 14 complex U-shaped sacral fractures which had been treated from January 2014 to December 2019, involved 10 males and 4 females, aged 24 to 48 (35.4±6.5) years. Fracture healing time, nerve function, clinical function and complications were observed in the patients. RESULTS: All patients were followed up for 9 to 16(26.0±5.9) months. The complete weight-bearing time for bone healing was(12.4±2.0) weeks. One case of surgical incision infection occurred after operation, and one case of sacrum nailspenetrated to the outer plate of sacrum. No complications such as pressure ulcers, loosening or rupture of internal fixation occurred. According to Gibbons scoring, the neurological function recovered from preoperative 2.9±0.9 to postoperative 2.1±1.1, there were statistically significant differences between preoperative and postoperative (t=6.9, P=0.00). There was significant difference between preoperative malformation angle (41.4±11.2)° and postoperative value (28.3±7.5)° (t=4.70, P=0.00). According to Majeed scoring to evaluate the clinical function, postoperative pain, standing, sitting, sexual life, work ability, total score respectively were 23.21±3.17, 25.57± 3.94, 7.71±1.54, 2.64±0.92, 16.14±2.41, 75.30±8.10, 2 cases got excellent results, 10 good, 2 fair. CONCLUSION: Sacral lumbar fixation is an effective method for the treatment of U-shaped sacrum fractures. It has the advantages of strong internal fixation and satisfactory functional recovery.

Ipsilateral femoral neck and shaft fracture in children: Two case reports.

RATIONALE: Pediatric femoral shaft combined with ipsilateral femoral neck fractures are very rare but challenging injuries fraught with the development of avascular necrosis, coxa vara, and leg length discrepancy. Majority of the previous reports indicated the neck femur fracture was fixed with cannulated screws or/and pins, femoral shaft fracture was stabilized with a plate and screws. However, we used cannulated screws combined with elastic stable intramedullary nails to minimally invasive procedures treat this type of injury and achieved good follow-up results. PATIENT CONCERNS: A 7-year-old boy (Case 1) was hospitalized due to a traffic accident resulting in swelling and deformity of the right thigh accompanied by limited mobility of hip and knee. A 5-year-old male child (Case 2) presented with pain and swelling in the bilateral lower limb after fall from approximately 12 feet. DIAGNOSES: Physical examination, X-ray film, and computed tomography were performed. Both patients were diagnosed with ipsilateral femoral neck and shaft fracture. INTERVENTIONS: The fractures were reduced closed by image-intensifier imaging. Two partially threaded cancellous screws were used to fix femoral neck fracture, and elastic intramedullary nails were performed to stable the femoral shaft fracture. Postoperatively, the patients were immobilized in a one-and-a-half hip spica cast for six weeks. The internal fixations were removed after one year. OUTCOMES: Case one was follow-up at 14 months and the other one was followed up for 3 years. And at the last follow-up showed a normal and painless hip function. No clinical complications were found during follow-up visit, including head penetration, implant failure, fracture nonunion, avascular necrosis and hip varus deformity. LESSONS: Clinician should carefully check and read relevant imaging data to avoid missed diagnosis. And the internal fixation method described in this paper may be more minimally invasive.

[Comparison of different minimally invasive internal fixation in the treatment of pelvic anterior ring fracture].

OBJECTIVE: To compare the clinical efficacy of three minimally invasive methods of anterior column screw, plate and screw rod system in the treatment of anterior pelvic ring fracture. METHODS: From December 2015 to September 2018, 77 patients with pelvic anterior ring fracture were treated and followed up, including 45 males and 32 females, aged 19 to 73 years. According to AO / OTA classification, there were 26 cases of type B1, 20 cases of type B2, 17 cases of type B3 and 14 cases of type C. According to the different internal fixation methods, they were divided into three groups:anterior column screw group(35 cases), plate group(20 cases), and screw rod system group(22 cases). The operation time, intraoperative fluoroscopy times, blood loss, fracture reduction quality, complications and curative effect of the three groups were compared. RESULTS: All 77 patients were followed up for 12 to 33 (16.5±5.7) months. The operation time, intraoperative blood loss and incision length of anterior column screw group were significantly shorter than those of plate group and screw rod system group, and intraoperative fluoroscopy times of plate group were significantly less than those of anterior column screw group and screw rod system group (P<0.05). There was no significant difference in the quality of fracture reduction and curative effect among the three groups(P>0.05). The incidence of complications was significant different among three group(P<0.05). CONCLUSION: Minimally invasive internal fixation with anterior column screw, plate and screw rod system can obtain good clinical effect, but anterior column screw fixation has less trauma and lower incidence of surgicalcomplications.

[Progress on diagnosis and treatment of cartilage injury of the talus].

The diagnosis of osteochondral lesions of the talus can be based on the patients' symptoms, medical history, MRI, detailed physical examination and arthroscopy. Its treatment includes conservative treatment and surgical treatment. Conservative treatment includes rest, partial-weight bearing, plaster immobilization, wear the orthopedic support, take the non-steroidal anti-inflammatory drugs and so on. Conservative treatment is less risky and effective for mild injuries. Surgical treatment includes debridement, marrow stimulation, internal fixation and cartilage transplantation, autologous chondrocyte transplantation, articular cavity injection biological additions, ultrasonic and electromagnetic stimulation technology, tissue engineering technology, etc. Currently, there are various treatment methods, each with indications and advantages and disadvantages. Among these methods, the most commonly used ones are debridement, marrow stimulation, cartilage transplantation and autologous chondrocyte transplantation, and they deserve extensive promotion. Debridement and marrow stimulation are performed minimally traumatically under arthroscopy. The operation is simple and inexpensive with positive effects and mild pain. There is a higher rate of success for small-scale injuries, but if the operation fails, it will result in a wider range of defects, because of the fibrous cartilages formed after the operation. The cartilage transplantation can be performed in an one-stage operation. After the operation, the hyaline cartilage can be restored, but there are different levels of pathological changes in the donor sites. Chondrocytes transplantation can solve the problem of larger osteochondral defects left after the initial treatment failure, and the donor cartilage can be repaired without affecting the donor sites. But the disadvantages are its long time treatment, staged operations and higher cost. As far as all these treatments are concerned, recent treatment effects are satisfactory, but the long-term efficacy is still questionable. For the autologous chondrocyte transplantation and emerging tissue engineering treatment technology, there is still broad research prospect.

[Surgical treatment of acetabular type C1 acetabular fracture by posteroproximal-posteroanterior sequential reduction and internal fixation].

OBJECTIVE: To investigate the operative reduction techniques and clinical results of surgical treatment of type C1 (AO/ASIF) acetabular fracture by posteroproximal-posteroanterior sequential reduction and internal fixation. METHODS: From August 2004 to January 2012, 13 patients with type C1 (AO/ASIF) acetabular fracture were treated by posteroproximal-posteroanterior sequential reduction and internal fixation. Of them, 8 cases were male and 5 cases were female with an average age of 42 years years old (ranged, 18 to 64). Pelvis 3-dimentional CT reconstruction were used to confirmed the classification of fracture, and the operation were performed during from 5 to 20 days with an average of 9.5 days. Operation time, blood loss, complications and reduction were recorded and evaluated. The function of hip joint were accessed at the final follow-up. RESULTS: The operation time ranged from 190 to 290 min with an average of 240 min. The mean blood loss was 1 800 ml (ranged, 1 300 to 3 000 ml). One case had superficial infection and healed after 3 weeks. According to Matta reduction criteria, 8 cases obtained anatomical reduction, 4 cases got satisfied results and 1 cases got unsatisfied results. Eleven cases were followed up with an average of (24.0 +/- 8.0) months, and 2 cases were lost to follow-up. According to revised Mede d'Aubingne and Postel evaluation system, 7 cases got excellent results, 2 good, 1 moderate and 1 poor. CONCLUSION: Posteroproximal-posteroanterior sequential reduction and internal fixation for the treatment of type C1 (AO/ASIF) acetabular fracture can achieve satisfied surgical proces and operation quality.