Combining thermal imaging and spectral pyrometry for express temperature mapping in additive manufacturing.

A compact and low-cost two-dimensional (2D) thermal imager was developed for real-time temperature mapping of a melt pool during coaxial laser cladding (the additive manufacturing technique). The device combines a color CMOS camera and a compact spectrometer. The spectrometer was utilized for internal calibration and validation of a 2D temperature map that was acquired by the CMOS camera. The remarkable feature of the thermal imager is that camera images are calibrated directly during the measurement process utilizing spectral pyrometry. Additionally, the spectrometer decreased a potential systematic error due to a spectrum contribution from atomic/ionic lines emission. The spectral pyrometry provided temperature accuracy measurements of ±23K while two-dimensional (2D) temperature mapping by two-color pyrometry accuracy was estimated as ±38K in the range of 1700-3500 K. The system has been installed at a coaxial laser cladding head for real-time temperature mapping. The system was developed for measuring a melt pool during laser cladding production of a high wear-resistant coating (tungsten carbide particles in a nickel matrix). Tungsten carbides powder flow rate has been changed sequentially from 5 to 27 g/min by powder feeder programming, which resulted in a variation of melt pool dimensions and temperature maps during the cladding process.

In situ laser-induced breakdown spectroscopy measurements during laser welding of superalloy.

Laser-induced breakdown spectroscopy (LIBS) has been utilized for in situ diagnostics of the laser welding process. The influence of different weld spot areas (melt pool, solid weld) on LIBS signals and plasma properties has been studied in detail. Liquid metal sampling and high target surface temperature of the melt enhance LIBS plasma intensity and increase plasma temperature. The influence of laser welding process parameters on LIBS measurements has been studied in order to differentiate optimal and defective laser welding. In case of defective laser welding, the melt pool was intensively boiling, so we have observed greater LIBS signals but poor reproducibility. For the first time, the LIBS technique was demonstrated to detect defective laser welding during in situ measurements utilizing atomic and ionic line comparison by paired sample t-test hypotheses testing.

Surface plasma influence on nanosecond laser ablation.

The comparison of laser ablation and plasma evolution has been carried out for a molten steel sample in the absence and in the presence of surface plasma. A continuous wave (cw) laser beam was utilized for local melting of a steel (Fe>99 wt.%) sample, but it also induced a surface plasma according to optical emission spectroscopy. The cw laser was switched off for a few milliseconds to dissipate the surface plasma, but the surface temperature did not change according to optical pyrometer measurements. Molten metal was ablated by a nanosecond Nd:YAG laser pulse during cw laser operation and when it was switched off for 5 milliseconds. Comparison of laser ablation and plasma evolution in the presence and in the absence of the near-surface plasma induced by the cw laser beam has been carried out. Time-integrated plasma imaging detected slightly greater emissivity of the plasma induced during cw laser operation. The cw laser operation resulted in a twofold enhancement of the intensity of atomic lines in the spectra as well as slower decay of plasma emission. Plume temperature and electron density were slightly greater at early stages of plume expansion in surface plasma.

Optimizing laser crater enhanced Raman spectroscopy.

Raman signal enhancement by laser crater production was systematically studied for 785 nm continuous wave laser pumping. Laser craters were produced in L-aspartic acid powder by a nanosecond pulsed solid state neodymium-doped yttrium aluminum garnet laser (532 nm, 8 ns, 1 mJ/pulse), while Raman spectra were then acquired by using a commercial spectrometer with 785 nm laser beam pumping. The Raman signal enhancement effect was studied in terms of the number of ablating pulses used, the lens-to-sample distance, and the crater-center-laser-spot offset. The influence of the experiment parameters on Raman signal enhancement was studied for different powder materials. Maximum Raman signal enhancement reached 11 fold for loose powders but decreased twice for pressed tablets. Raman signal enhancement was demonstrated for several diverse powder materials like gypsum or ammonium nitrate with better results achieved for the samples tending to give narrow and deep craters upon the laser ablation stage. Alternative ways of cavity production (steel needle tapping and hole drilling) were compared with the laser cratering technique in terms of Raman signal enhancement. Drilling was found to give the poorest enhancement of the Raman signal, while both laser ablation and steel needle tapping provided comparable results. Here, we have demonstrated for the first time, to the best of our knowledge, that a Raman signal can be enhanced 10 fold with the aid of simple cavity production by steel needle tapping in rough highly reflective materials. Though laser crater enhancement Raman spectroscopy requires an additional pulsed laser, this technique is more appropriate for automatization compared to the needle tapping approach.

Optimizing laser crater enhanced Raman scattering spectroscopy.

The laser crater enhanced Raman scattering (LCERS) spectroscopy technique has been systematically studied for chosen sampling strategy and influence of powder material properties on spectra intensity enhancement. The same nanosecond pulsed solid state Nd:YAG laser (532 nm, 10 ns, 0.1-1.5 mJ/pulse) was used for laser crater production and Raman scattering experiments for l-aspartic acid powder. Increased sampling area inside crater cavity is the key factor for Raman signal improvement for the LCERS technique, thus Raman signal enhancement was studied as a function of numerous experimental parameters including lens-to-sample distance, wavelength (532 and 1064 nm) and laser pulse energy utilized for crater production. Combining laser pulses of 1064 and 532 nm wavelengths for crater ablation was shown to be an effective way for additional LCERS signal improvement. Powder material properties (particle size distribution, powder compactness) were demonstrated to affect LCERS measurements with better results achieved for smaller particles and lower compactness.

Laser-induced breakdown spectroscopy for three-dimensional elemental mapping of composite materials synthesized by additive technologies.

Three-dimensional multi-elemental mapping of composite wear-resistant coatings by laser-induced breakdown spectroscopy has been demonstrated for the first time, to the best of our knowledge. Individual clads of 1560 nickel alloy reinforced with tungsten carbide were synthesized by a co-axial laser cladding technique. Electron energy dispersive x-ray spectroscopy revealed elemental maps for major elements (W, Ni, Co, Cr, Fe) but failed to measure silicon and carbon. Laser-induced breakdown spectroscopy was utilized for elemental mapping of carbon and all other elements of interest. It was demonstrated that three-dimensional elemental profiling for a few tens of micrometers requires substantial laser spot overlapping during the scanning procedure in order to achieve good accuracy of depth measurements. Elemental maps for nickel, iron, chromium, silicon, tungsten, and carbon were quantified for 900 µm×900 µm×45 µm volume with 30 µm lateral and 4 µm depth resolution in the case of tungsten carbide particles in nickel alloy.

[The prevention of the acute urine retention and lower urinary tract infection after rectum surgery].

The possibilities of the prevention of the acute urine retention in patients with the prostatic enlargement after the rectum surgery. The method was successfully used in 106 patients.

Superspiralization of chiral strings.

A phenomenon of superspiralization was revealed in homochiral solutions of biomimetics with strings lengths from 10(2) nm to 10(2) µ and longer: strings of greater size spontaneously formed in solution are twined of the smaller strings, which also have a helical structure. The chiral pitch depends on the conditions of formation of a particular string and can vary by several times in different strings of the same specimen.

[Endosurgery in treatment of urinary bladder cancer in elderly patients].

Treatment of 162 patients with micro- and macrohematuria was analyzed. Urinary bladder cancer was diagnosed in 156 of them (men--127, women--29). All patients received endoscopic treatment (transurethral resection). An average age of patients was 74.4±7.9 years. 142 (91.1%) of patients were older then 60 years. The transitional cell carcinoma was diagnosed in 118 patients. The urinary bladder cancer recurrence was diagnosed in 13 (9.2%) patients steged T1 and in 24 (16.9%) staged T2. Only 2 patients with T3 stage of the disease were considered to be unsuitable for endoscopic transurethral resection and received an open argon tumor vaporization.

[Emergency oncourological surgery in senile patients].

Many questions of treatment tactics in senile patients remain not quite clear. It is necessary to work out an algorithm of surgical treatment depending on severity of somatic status of the patient and life prognosis. It is difficult to make a decision concerning the necessity and perspectivity of palliative surgical treatment of oncological patients at late stages. Taking into account the complicacy in prediction of dynamics of malignant growth, active surgical tactics with thorough supervision of senile patients with grave somatic status is preferable.

Dynamics of high repetition rate regenerative amplifiers.

Dynamics features of high repetition rate continuously pumped solid-state regenerative amplifiers were studied numerically. A space independent rate equations and discrete-time dynamical system approach were used for system state evolution analysis. Regular single-energy operation, quasi-periodic pulsing and chaotic behavior regions are distinguished in space of control parameters. Diagrams of dynamical regimes comprehensively exhibiting operation features of the system are presented. Seed energy is shown to be an important parameter determining the stability space. Conditions of stable operation are described quantitatively.

[An original modification of wedge resection of the kidney in renal cell carcinoma].

Organ-preserving surgery was made in 133 patients with renal cell carcinoma. An original modification of renal resection with administration of the drug tachocomb was conducted in 22 patients. Short- and long-term surgical outcomes demonstrate advantages of the surgery supported by the results of postoperative monitoring including ultrasound angiography, computed and magnetic resonance imaging.

[Ways of overcoming drug resistance in patients with pulmonary tuberculosis]. / Puti preodoleniia lekarstvennoi rezistentnosti u bol'nykh tuberkulezom legkikh.

To elucidate the combined effect of surfactants and antituberculous drugs, the surfactant myrastimine was tested. Two series of sputum cultures with multidrug-resistant Mycobacterium tuberculosis (MBT) strains were made. The experimental results confirmed that myramistine noticeably enhanced the sensitivity of multidrug-resistant MBT strains to antituberculous agents. The use of endobronchial and intracavernous myramistine in combination with antituberculous agents to patients with destructive pulmonary tuberculosis caused by multidrug-resistant MBT strains reduced the latter's resistance to antibiotics, cured tubendobronchitis in most patients, created conditions for obliteration of the cavernous cavity. Positive changes are noted in the first 4 months after the initiation of therapy, which can prepare patients for surgical treatment more rapidly.

[Ultrasound angiography: new perspectives in diagnosis of renal mass lesions]. / Ul'trazvukovaia angiografiia: novye vozmozhnosti diagnostiki ob"emnykh obrazovanii pochek.

AIM: To evaluate diagnostic efficacy of advanced ultrasound (US) techniques in early and differential diagnosis of malignant tumors of the kidneys. MATERIAL AND METHODS: A total of 394 patients with renal mass lesions were studied. They had: renal cell carcinoma (n = 96), renal parenchyma pseudotumors (n = 22), lipoma (n = 48), angiomyolipoma (n = 19), renal abscess (n = 2), renal sinus lipomatosis (n = 1), parenchymal cysts (n = 205), retroperitoneal leiomyosarcoma with invasion in the kidney (n = 1). The following examinations were made: gray scale study with tissue harmonic imaging, panoramic scanning, US-angiography (color doppler imaging--CDI, power doppler imaging--PDI, 3D-reconstruction of the kidney vessels, 3D dynamic contrast enhanced angiography (DCEA) in the second harmonic mode with an echo-contrast agent levovist. Pulse Doppler with qualitative and quantitative evaluation of the doppler spectrum was used as an additional method. Verification of the diagnosis was made by conventional angiography, computer tomography, MR-tomography, histomorphological analysis after surgery in 91, 310, 6 and 88 patients, respectively. RESULTS: New US techniques allow differentiation of malignant tumors with renal lipomas and angiomyolipomas, focuses of inflammation, pseudotumors of the renal parenchyma and atypical renal cysts. CDI has revealed big pathologic vessels with arterio-venous and arterio-arterial shunts in renal cancer in 63.5% of the cases. PDI visualized a net of pathologically changed vessels in 74.8% of the cases. 3D-reconstruction in PDI was highly sensitive (90%) in visualization of neoplastic vessels. US-angiography was used for pre- and postoperative monitoring in 18 patients subjected to conservative renal surgery. In 23 patients DCEA with levovist allowed monitoring of all phases of contrast enhancement of renal vessels. Injection of contrast agent revealed tumor microvasculature in an early arterial phase (20-30 seconds). CONCLUSION: US-angiographic techniques in diagnosis of renal cancer increases sensitivity and specificity of the US method compared to conventional B-mode US from 55 and 60% to 98 and 95%, positive and negative predictive value from 58 and 57% to 95 and 98%, respectively.

[Diagnosis of bladder cancer]. / Diagnostika raka mochevogo puzyria.

Increasing incidence of bladder tumors necessitates development of new techniques of early diagnosis. A total clinical system including application of ultrasonoangiography proved superior to examination under the gray scale mode. The diagnostic and monitoring algorithm makes the system highly effective.

[Conservative surgery of renal cancer]. / Organosokhraniaiushchie operatsii pri rake pochki.

Organ-preserving technologies are coming up to take the place of organ-removing operations for cancer of the kidney. A tumor size is not a decisive parameter any more as the decision is made in each individual case. Ultrasound, as a screening test, has changed the situation in the diagnosis of early stages of the disease, but routine urological examinations retain their importance. Postoperative monitoring with US angiography is essential for detecting relapses.

[Rehabilitation of patients undergoing surgery for bronchiectasis]. / Rebilitatsiia bol'nykh, operirovannykh po povodu bronkhoéktaticheskoi bolezni.

The results of resection operations on 94 patients with bronchiectatic disease were analyzed. Clinical research or proof remission was marked for 81.3%, the restoration of working ability--for 85.3% of patients. After the operation complications were revealed in 25.5% of patients. The most of them were concerning the increased exudation in pleural cavity and its infection. For proving of the rehabilitation outcomes before the operation carry out the course of complex therapy, including the sanation of bronchial tree.

[Aspects of the onset and clinical course of pulmonary abscess]. / Osobennosti formirovaniia i techeniia khronicheskogo abstsessa legkogo.

The causes of formation and variants of clinical course of chronic pulmonary abscess were analysed in 166 patients. The main cause of the disease transition into chronic stage is nontimely and nonadequate therapy with insufficient usage of pathogenetic and instrumental methods.