Laparoscopic spleen-preserving total pancreatectomy for the treatment of low-grade malignant pancreatic tumors:Two case reports and review of literature

BACKGROUND Function-preserving pancreatectomy can improve the long-term quality of life of patients with benign or low-grade malignant tumors,such as intraductal papillary mucinous neoplasms(IPMNs)and mucinous cystic neoplasms.However,there is limited literature on laparoscopic spleen-preserving total pancreatectomy(LSpTP)due to technical difficulties.CASE SUMMARY Patient 1 was a 51-year-old male diagnosed with IPMN based on preoperative imaging,showing solid nodules in the pancreatic head and diffuse dilation of the main pancreatic duct with atrophy of the distal pancreas.We performed L-SpTP with preservation of the splenic vessels,and the postoperative pathology report revealed IPMN with invasive carcinoma.Patient 2 was a 60-year-old male with multiple cystic lesions in the pancreatic head and body.L-SpTP was performed,and intraoperatively,the splenic vein was injured and required ligation.Postoperative pathology revealed a mucinous cystic tumor of the pancreas with low-grade dysplasia.Both patients were discharged on postoperative day 7,and there were no major complications during the perioperative period.CONCLUSION We believe that L-SpTP is a safe and feasible treatment for low-grade malignant pancreatic tumors,but more case studies are needed to evaluate its safety,efficacy,and long-term outcomes.

Early Silurian Wuchuan–Sihui–Shaoguan exhalative sedimentary pyrite belt, South China: constraints from zircon dating for K-bentonite of the giant Dajiangping deposit

The Wuchuan-Sihui-Shaoguan(WSS)exhalative sedimentary pyrite belt in the southwestern part of the Qinzhou-Hangzhou(Qin-Hang)belt is the most important sulfur industry base in China.However,a wide range of metallogenetic ages spanning from Ediacaran to Devonian has been reported in the literature.This age range does not support the idea that the typical character of"coeval mineralization"in an exhalative sedimentary mineralization belt in China and worldwide.Therefore,the precise determination of mineralization ages of representative deposits is necessary to provide guides for exploration and metallogenetic models.The Dajiangping pyrite deposit is a typical example of this kind of deposits and is also the largest deposit with a proven reserve of 210 Mt.This deposit was thought to have formed in Ediacaran or Devonian.In this study,2-3 layers of 10-25 cm thick 2M1-type microcrystalline muscovite slate abruptly embedded in the No.Ⅳmassive orebody of the deposit has been identified to be low-grade metamorphic K-bentonite.A Concordia zircon LA-ICP-MS U-Pb age of 432.5±1.3 Ma(mean standard weighted deviation of concordance and equivalence=1.2;N=11)has been yielded for the low-grade metamorphic K-bentonite.This age is distinctly different from the Rb-Sr isochron age of630.1±7.3 Ma for siliceous rock at the top of the No.Ⅲbanded orebody and the Re-Os isochron age of 389±62 Ma for pyrites from a laminated orebody.Instead,it is close to the intercept age(429 Ma)of the youngest detrital zircons from sandstone interlayers of the No.Ⅲbanded orebody.The Concordia age is also coincident with those of the Late Caledonian(400-460 Ma)magmatism-metamorphism events which are widely distributed in Cathaysia Block.Particularly,it agrees well with that of the Early Silurian extensional volcanism(434-444 Ma)which have been revealed in the Dabaoshan,Siqian-Hekou,and Nanjing volcanic basins in northern Guangdong Province and southern Jiangxi Province.Hence,the dating result in this study confirms that the sedimentary time of the ore-host Daganshan Formation is Early Silurian,and implies that the mineralization age of the Dajiangping pyrite deposit should also be Early Silurian.In combination with the Early Silurian age of Shezui pyrite deposit and the Dabaoshan volcanic basin along the WSS pyrite belt,it could be inferred that the WSS pyrite belt provides a record of the northern expanding of Qinzhou-Fangcheng trough in Early Silurian and that the exhalative pyrite mineralization was triggered by the postcollisional extension of the margin of Cathaysia Block after the intracontinental collision between Cathaysia Block and Yangtze Block during Late Caledonian stage.

A decomposing technique for scheelite concentrate and low-grade scheelite concentrate

The effect of different decomposition conditions on tungsten recovery forscheelite concentrate has been examined. The results show that tungsten recovery can be more than98% under decomposing conditions as follows: the amount of caustic soda is 2.2 and 3.2 times oftheoretical respectively, ratio of water and ore is 0.7-0.8, temperature is 160℃, and preservationtime is 2.0 h for scheelite concentrate (63.21 % WO_3) and low grade scheelite concentrate (55.17%WO_3).

SODA DECOMPOSITION OF LOW－GRADE TUNGSTEN ORE THROUGH MECHANICAL ACTIVATION

Leaching of lowgrade refractory tungsten ore was carried out through mechanical activation. The effect of temperature, amount of Na2CO3, addition of NaOH, ratio of liquid to solid and leaching time on the recovery of WO3 was studied. The WO3 recovery upto 96%～99% has been achieved when the tungsten ore was digested by soda not more than three times stiochiometric amount at 185～195 ℃ for 10～20 h. The WO3 recovery can increase 10%～15% compared to that of conventional soda autoclave process.

Single-incision laparoscopic cecectomy for low-grade appendiceal mucinous neoplasm after laparoscopic rectectomy

In this case report,we discuss single-incision laparoscopic cecectomy for low-grade appendiceal neoplasm after laparoscopic anterior resection for rectal cancer.The optimal surgical therapy for low-grade appendiceal neoplasm is controversial;currently,the options include appendectomy,cecectomy,right hemicolectomy,and open or laparoscopic surgery.Due to the risk of pseudomyxoma peritonei,complete resection without rupture is necessary.We have encountered 5 cases of lowgrade appendiceal neoplasm and all 5 patients had no lymph node metastasis.We chose the appendectomy or cecectomy without lymph node dissection if preoperative imaging studies did not suspect malignancy.In the present case,we performed cecectomy without lymph node dissection by single-incision laparoscopic surgery(SILS),which is reported to be a reduced port surgery associated with decreased invasiveness and patient stress compared with conventional laparoscopic surgery.We are confident that SILS is a feasible alternative to traditional surgical procedures for borderline tumors,such as low-grade appendiceal neoplasms.

Extraction of niobium, yttrium, and cerium from a low-grade niobium-bearing ore by roasting(NH_4)_2SO_4-Na_2SO_4-H_2SO_4 system

A novel process of extracting niobium, yttrium,and cerium from a low-grade niobium-bearing ore by the roasting（NH4）2SO4-Na2SO4-H2SO4 system was experimentally studied. The influences of various factors,such as roasting temperature, roasting time, mass ratio of agents-to-ore and particle size fraction on the extraction of valuable metals were comprehensively investigated. It is found that the roasting Na2SO4-H2SO4 system is effective to extract the niobium, yttrium, and cerium. The obtained optimum conditions for the extraction of Nb, Y, and Ce are roasting temperature of 300 °C, roasting time of 3 h, mass ratio of Na2SO4：H2SO4：Ore of 0.5：1.0：1.0, and particle size fraction of-74 lm（~95 %）. Under the optimum condition, the maximum recovery of Nb, Y, and Ce can reach90.53 %, 92.15 %, and 98.04 %, respectively. All the results generated from this study will provide the fundamentals for Nb, Y, and Ce extraction from a niobiumbearing ore with low-grade.